U.S. patent application number 17/188398 was filed with the patent office on 2021-06-17 for apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals.
This patent application is currently assigned to LG ELECTRONICS INC.. The applicant listed for this patent is LG ELECTRONICS INC.. Invention is credited to Sungryong HONG, Woosuk KO, Woosuk KWON, Kyoungsoo MOON, Sejin OH.
Application Number | 20210185486 17/188398 |
Document ID | / |
Family ID | 1000005429912 |
Filed Date | 2021-06-17 |
United States Patent
Application |
20210185486 |
Kind Code |
A1 |
KWON; Woosuk ; et
al. |
June 17, 2021 |
APPARATUS FOR TRANSMITTING BROADCAST SIGNALS, APPARATUS FOR
RECEIVING BROADCAST SIGNALS, METHOD FOR TRANSMITTING BROADCAST
SIGNALS AND METHOD FOR RECEIVING BROADCAST SIGNALS
Abstract
A method of transmitting broadcast signals, includes link layer
processing input packets to generate link layer packets, wherein a
link layer packet of the link layer packets includes a header and a
payload, wherein the payload of the link layer packet includes a
segment of an input packet or concatenated input packets, wherein
the header of the link layer packet includes a first field for
identifying whether the payload includes the segment or the
concatenated input packets, wherein the header further includes a
second field for identifying a number of the concatenated input
packets and third fields that are included in the header in the
same order as the concatenated input packets present in the payload
in response to the first field representing that the payload
includes the concatenated input packets, and wherein the third
fields represent a length of each of the concatenated input
packets.
Inventors: |
KWON; Woosuk; (Seoul,
KR) ; KO; Woosuk; (Seoul, KR) ; HONG;
Sungryong; (Seoul, KR) ; OH; Sejin; (Seoul,
KR) ; MOON; Kyoungsoo; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
|
KR |
|
|
Assignee: |
LG ELECTRONICS INC.
Seoul
KR
|
Family ID: |
1000005429912 |
Appl. No.: |
17/188398 |
Filed: |
March 1, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16453376 |
Jun 26, 2019 |
10952035 |
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17188398 |
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15875910 |
Jan 19, 2018 |
10362450 |
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16453376 |
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14906796 |
Jan 21, 2016 |
9913106 |
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PCT/KR2015/000367 |
Jan 14, 2015 |
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15875910 |
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61927453 |
Jan 14, 2014 |
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61926958 |
Jan 14, 2014 |
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61935863 |
Feb 5, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N 21/64322 20130101;
H04W 4/06 20130101; H04B 7/0413 20130101; H04H 60/07 20130101; H04N
21/2362 20130101; H04H 20/00 20130101; H04N 21/2383 20130101; H04L
69/22 20130101; H04L 1/0041 20130101 |
International
Class: |
H04W 4/06 20060101
H04W004/06; H04L 1/00 20060101 H04L001/00; H04H 20/00 20060101
H04H020/00; H04L 29/06 20060101 H04L029/06 |
Claims
1. A method of transmitting broadcast signals, the method
comprising: link layer processing input packets to generate link
layer packets, wherein a link layer packet of the link layer
packets includes a header and a payload, wherein the payload of the
link layer packet includes a segment of an input packet or
concatenated input packets, wherein the header of the link layer
packet includes a first field for identifying whether the payload
includes the segment or the concatenated input packets, wherein the
header further includes a second field for identifying a number of
the concatenated input packets and third fields that are included
in the header in the same order as the concatenated input packets
present in the payload in response to the first field representing
that the payload includes the concatenated input packets, wherein
the third fields represent a length of each of the concatenated
input packets, wherein a number of the third fields is determined
based on the number of the concatenated input packets, wherein,
when the number of the third fields is odd, stuffing bits are added
after the third fields, and wherein at least one of the link layer
packets is for link layer signaling; physical layer processing the
link layer packets into the broadcast signals; and transmitting the
broadcast signals.
2. The method of claim 1, wherein a value of the second field is
set to the number of the concatenated input packets--2.
3. The method of claim 1, wherein a minimum possible number of the
concatenated input packets is 2 in the link layer packet.
4. The method of claim 1, wherein a maximum possible number of the
concatenated input packets is 9 in the link layer packet.
5. The method of claim 1, wherein a number of the stuffing bits is
4.
6. An apparatus for transmitting broadcast signals, the apparatus
comprising: a first processor to link layer process input packets
to generate link layer packets, wherein a link layer packet of the
link layer packets includes a header and a payload, wherein the
payload of the link layer packet includes a segment of an input
packet or concatenated input packets, wherein the header of the
link layer packet includes a first field for identifying whether
the payload includes the segment or the concatenated input packets,
wherein the header further includes a second field for identifying
a number of the concatenated input packets and third fields that
are included in the header in the same order as the concatenated
input packets present in the payload in response to the first field
representing that the payload includes the concatenated input
packets, wherein the third fields represent a length of each of the
concatenated input packets, wherein a number of the third fields is
determined based on the number of the concatenated input packets,
wherein, when the number of the third fields is odd, stuffing bits
are added after the third fields, and wherein at least one of the
link layer packets is for link layer signaling; a second processor
to physical layer process the link layer packets into the broadcast
signals; and a transmitter to transmit the broadcast signals.
7. The apparatus of claim 6, wherein a value of the second field is
set to the number of the concatenated input packets--2.
8. The apparatus of claim 6, wherein a minimum possible number of
the concatenated input packets is 2 in the link layer packet.
9. The apparatus of claim 6, wherein a maximum possible number of
the concatenated input packets is 9 in the link layer packet.
10. The apparatus of claim 6, wherein a number of the stuffing bits
is 4.
11. A method of receiving broadcast signals, the method comprising:
receiving the broadcast signals; physical layer processing the
broadcast signals into link layer packets; and link layer
processing the link layer packets to restore input packets, wherein
a link layer packet of the link layer packets includes a header and
a payload, wherein the payload of the link layer packet includes a
segment of an input packet or concatenated input packets, wherein
the header of the link layer packet includes a first field for
identifying whether the payload includes the segment or the
concatenated input packets, wherein the header further includes a
second field for identifying a number of the concatenated input
packets and third fields that are included in the header in the
same order as the concatenated input packets present in the payload
in response to the first field representing that the payload
includes the concatenated input packets, wherein the third fields
represent a length of each of the concatenated input packets,
wherein a number of the third fields is determined based on the
number of the concatenated input packets, wherein, when the number
of the third fields is odd, stuffing bits are added after the third
fields, and wherein at least one of the link layer packets is for
link layer signaling.
12. The method of claim 11, wherein a value of the second field is
set to the number of the concatenated input packets--2.
13. The method of claim 11, wherein a minimum possible number of
the concatenated input packets is 2 in the link layer packet.
14. The method of claim 11, wherein a maximum possible number of
the concatenated input packets is 9 in the link layer packet.
15. The method of claim 11, wherein a number of the stuffing bits
is 4.
16. An apparatus for receiving broadcast signals, the apparatus
comprising: a tuner to receive the broadcast signals; a first
processor to physical layer process the broadcast signals into link
layer packets; and a second processor to link layer process the
link layer packets to restore input packets, wherein a link layer
packet of the link layer packets includes a header and a payload,
wherein the payload of the link layer packet includes a segment of
an input packet or concatenated input packets, wherein the header
of the link layer packet includes a first field for identifying
whether the payload includes the segment or the concatenated input
packets, wherein the header further includes a second field for
identifying a number of the concatenated input packets and third
fields that are included in the header in the same order as the
concatenated input packets present in the payload in response to
the first field representing that the payload includes the
concatenated input packets, wherein the third fields represent a
length of each of the concatenated input packets, wherein a number
of the third fields is determined based on the number of the
concatenated input packets, wherein, when the number of the third
fields is odd, stuffing bits are added after the third fields, and
wherein at least one of the link layer packets is for link layer
signaling.
17. The apparatus of claim 16, wherein a value of the second field
is set to the number of the concatenated input packets--2.
18. The apparatus of claim 16, wherein a minimum possible number of
the concatenated input packets is 2 in the link layer packet.
19. The apparatus of claim 16, wherein a maximum possible number of
the concatenated input packets is 9 in the link layer packet.
20. The apparatus of claim 16, wherein a number of the stuffing
bits is 4.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of U.S. patent
application Ser. No. 16/453,376 filed Jun. 26, 2019, which is a
Continuation of U.S. patent application Ser. No. 15/875,910 filed
on Jan. 19, 2018 (now U.S. Pat. No. 10,362,450 issued on Jul. 23,
2019), which is a Continuation of U.S. patent application Ser. No.
14/906,796 filed on Jan. 21, 2016 (now U.S. Pat. No. 9,913,106,
issued on Mar. 6, 2018), which is the National Phase of PCT
International Application No. PCT/KR2015/000367 filed on Jan. 14,
2015, which claims the priority benefit under 35 U.S.C. .sctn.
119(e) to U.S. Provisional Application Nos. 61/927,453 filed on
Jan. 14, 2014, 61/926,958 filed on Jan. 14, 2014 and 61/935,863
filed on Feb. 5, 2014, all of these applications are hereby
expressly incorporated by reference into the present
application.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to an apparatus for
transmitting broadcast signals, an apparatus for receiving
broadcast signals and methods for transmitting and receiving
broadcast signals.
Discussion of the Related Art
[0003] As analog broadcast signal transmission comes to an end,
various technologies for transmitting/receiving digital broadcast
signals are being developed. A digital broadcast signal may include
a larger amount of video/audio data than an analog broadcast signal
and further include various types of additional data in addition to
the video/audio data. That is, a digital broadcast system can
provide HD (high definition) images, multi-channel audio and
various additional services. However, data transmission efficiency
for transmission of large amounts of data, robustness of
transmission/reception networks and network flexibility in
consideration of mobile reception equipment need to be improved for
digital broadcast.
SUMMARY OF THE INVENTION
[0004] An object of the present invention is to provide an
apparatus and method for transmitting broadcast signals to
multiplex data of a broadcast transmission/reception system
providing two or more different broadcast services in a time domain
and transmit the multiplexed data through the same RF signal
bandwidth and an apparatus and method for receiving broadcast
signals corresponding thereto.
[0005] Another object of the present invention is to provide an
apparatus for transmitting broadcast signals, an apparatus for
receiving broadcast signals and methods for transmitting and
receiving broadcast signals to classify data corresponding to
services by components, transmit data corresponding to each
component as a data pipe, receive and process the data
[0006] Still another object of the present invention is to provide
an apparatus for transmitting broadcast signals, an apparatus for
receiving broadcast signals and methods for transmitting and
receiving broadcast signals to signal signaling information
necessary to provide broadcast signals.
[0007] To achieve the object and other advantages and in accordance
with the purpose of the invention, as embodied and broadly
described herein, the present invention provides a method of
transmitting broadcast signals. The method of transmitting
broadcast signals includes generating plural input streams, wherein
each of the plural input streams include plural input packets; link
layer processing the input packets in the plural input streams to
generate link layer packets; physical layer processing the link
layer packets in physical layer, to generate the broadcast signals;
and transmitting the generated broadcast signals.
[0008] Preferably, the link layer processing includes link layer
processing one of the plural input streams based on transparent
mode, wherein the link layer processing one of the plural input
streams based on transparent mode includes: delivering the one of
the plural input streams to the physical layer without
encapsulating.
[0009] Preferably, the link layer processing includes link layer
processing one of the plural input streams based on normal mode,
wherein the link layer processing one of the plural input streams
based on normal mode includes: encapsulating the input packets in
the one of the plural input streams to generate the link layer
packets, and delivering the generated link layer packets to the
physical layer.
[0010] Preferably, the link layer processing one of the plural
input streams based on normal mode further includes: overhead
reduction processing the input packets in the one of the plural
input streams before encapsulating, by compressing headers of the
input packets.
[0011] Preferably, the link layer processing one of the plural
input streams based on normal mode further includes: extracting a
first signaling information from overhead reduction processed input
packets, wherein the first signaling information is a signaling
information to be transmitted in a dedicated transmission channel;
and delivering the extracted first signaling information to the
physical layer.
[0012] Preferably, the link layer processing one of the plural
input streams based on normal mode further includes: extracting
second signaling information, wherein the second signaling
information is for signaling data in the input packets;
encapsulating the extracted second signaling information to
generate link layer packets; and delivering the generated link
layer packets to the physical layer.
[0013] Preferably, the link layer packet includes a link layer
payload generated by using a segment of one of the input packets,
or by using concatenated input packets.
[0014] Preferably, the physical layer processing includes: physical
layer processing plural Plops (Physical Layer Pipes) including data
of the link layer packets, to generate the broadcast signals.
[0015] Preferably, the physical layer processing includes: physical
layer processing the first signaling information into the dedicated
transmission channel, to generate the broadcast signals.
[0016] Preferably, the input packets are one of TS (Transport
Stream) packet, IP (Internet Protocol) packet or GS (Generic
Stream) packet.
[0017] In other aspect, the present invention provides an apparatus
for transmitting broadcast signals. The apparatus for transmitting
broadcast signals includes a first module that generates plural
input streams, wherein each of the plural input streams include
plural input packets; a second module that link layer processes the
input packets in the plural input streams to generate link layer
packets; a third module that physical layer processes the link
layer packets, to generate the broadcast signals; and a fourth
module that transmits the generated broadcast signals.
[0018] Preferably, the second module link layer processes one of
the plural input streams based on transparent mode, wherein the
second module delivers the one of the plural input streams to the
third module without encapsulating.
[0019] Preferably, the second module link layer processes one of
the plural input streams based on normal mode, wherein the second
module encapsulates the input packets in the one of the plural
input streams to generate the link layer packets, and wherein the
second module delivers the generated link layer packets to the
third module.
[0020] Preferably, the second module overhead reduction processes
the input packets in the one of the plural input streams before
encapsulating, by compressing headers of the input packets.
[0021] Preferably, the second module extracts a first signaling
information from overhead reduction processed input packets,
wherein the first signaling information is a signaling information
to be transmitted in a dedicated transmission channel; and wherein
the second module delivers the extracted first signaling
information to the third module.
[0022] Preferably, the second module extracts second signaling
information, wherein the second signaling information is for
signaling data in the input packets; wherein the second module
encapsulates the extracted second signaling information to generate
link layer packets; and wherein the second module delivers the
generated link layer packets to the third module.
[0023] Preferably, the link layer packet includes a link layer
payload generated by using a segment of one of the input packets,
or by using concatenated input packets.
[0024] Preferably, the third module physical layer processes plural
Plops (Physical Layer Pipes) including data of the link layer
packets, to generate the broadcast signals.
[0025] Preferably, the third module physical layer processes the
first signaling information into the dedicated transmission
channel, to generate the broadcast signals.
[0026] Preferably, the input packets are one of TS (Transport
Stream) packet, IP (Internet Protocol) packet or GS (Generic
Stream) packet.
[0027] The present invention can process data according to service
characteristics to control QoS (Quality of Services) for each
service or service component, thereby providing various broadcast
services.
[0028] The present invention can achieve transmission flexibility
by transmitting various broadcast services through the same RF
signal bandwidth.
[0029] The present invention can improve data transmission
efficiency and increase robustness of transmission/reception of
broadcast signals using a MIMO system.
[0030] According to the present invention, it is possible to
provide broadcast signal transmission and reception methods and
apparatus capable of receiving digital broadcast signals without
error even with mobile reception equipment or in an indoor
environment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
[0032] FIG. 1 illustrates a structure of an apparatus for
transmitting broadcast signals for future broadcast services
according to an embodiment of the present invention.
[0033] FIG. 2 illustrates an input formatting block according to
one embodiment of the present invention.
[0034] FIG. 3 illustrates an input formatting block according to
another embodiment of the present invention.
[0035] FIG. 4 illustrates an input formatting block according to
another embodiment of the present invention.
[0036] FIG. 5 illustrates a BICM block according to an embodiment
of the present invention.
[0037] FIG. 6 illustrates a BICM block according to another
embodiment of the present invention.
[0038] FIG. 7 illustrates a frame building block according to one
embodiment of the present invention.
[0039] FIG. 8 illustrates an OFDM generation block according to an
embodiment of the present invention.
[0040] FIG. 9 illustrates a structure of an apparatus for receiving
broadcast signals for future broadcast services according to an
embodiment of the present invention.
[0041] FIG. 10 illustrates a frame structure according to an
embodiment of the present invention.
[0042] FIG. 11 illustrates a signaling hierarchy structure of the
frame according to an embodiment of the present invention.
[0043] FIG. 12 illustrates preamble signaling data according to an
embodiment of the present invention.
[0044] FIG. 13 illustrates PLS1 data according to an embodiment of
the present invention.
[0045] FIG. 14 illustrates PLS2 data according to an embodiment of
the present invention.
[0046] FIG. 15 illustrates PLS2 data according to another
embodiment of the present invention.
[0047] FIG. 16 illustrates a logical structure of a frame according
to an embodiment of the present invention.
[0048] FIG. 17 illustrates PLS mapping according to an embodiment
of the present invention.
[0049] FIG. 18 illustrates EAC mapping according to an embodiment
of the present invention.
[0050] FIG. 19 illustrates FIC mapping according to an embodiment
of the present invention.
[0051] FIG. 20 illustrates a type of DP according to an embodiment
of the present invention.
[0052] FIG. 21 illustrates DP mapping according to an embodiment of
the present invention.
[0053] FIG. 22 illustrates an FEC structure according to an
embodiment of the present invention.
[0054] FIG. 23 illustrates a bit interleaving according to an
embodiment of the present invention.
[0055] FIG. 24 illustrates a cell-word demultiplexing according to
an embodiment of the present invention.
[0056] FIG. 25 illustrates a time interleaving according to an
embodiment of the present invention.
[0057] FIG. 26 illustrates the basic operation of a twisted
row-column block interleaver according to an embodiment of the
present invention.
[0058] FIG. 27 illustrates an operation of a twisted row-column
block interleaver according to another embodiment of the present
invention.
[0059] FIG. 28 illustrates a diagonal-wise reading pattern of a
twisted row-column block interleaver according to an embodiment of
the present invention.
[0060] FIG. 29 illustrates interleaved XFECBLOCKs from each
interleaving array according to an embodiment of the present
invention.
[0061] FIG. 30 is a conceptual diagram illustrating a protocol
stack for the next generation broadcast system based on hybrid
according to an embodiment of the present invention.
[0062] FIG. 31 is a conceptual diagram illustrating an interface of
a link layer according to an embodiment of the present
invention.
[0063] FIG. 32 is a conceptual diagram illustrating a packet
structure of a link elayer according to an embodiment of the
present invention.
[0064] FIG. 33 shows packet types dependent upon the packet type
element values according to an embodiment of the present
invention.
[0065] FIG. 34 is a conceptual diagram illustrating a header
structure of a link layer packet when an IP packet is transmitted
to the link layer according to an embodiment of the present
invention.
[0066] FIG. 35 is a conceptual diagram illustrating the meaning and
header structures according to C/S field values.
[0067] FIG. 36 is a conceptual diagram illustrating the meaning
according to the count field values.
[0068] FIG. 37 is a conceptual diagram illustrating the meaning and
segment lengths according to values of Seg_Len_ID field.
[0069] FIG. 38 is a conceptual diagram illustrating an equation for
encapsulating a normal packet and an equation for calculating a
link layer packet length.
[0070] FIG. 39 is a conceptual diagram illustrating a process for
encapsulating a concatenated packet and an equation for calculating
a link layer packet length.
[0071] FIG. 40 is a conceptual diagram illustrating a process for
calculating the length of a concatenated packet including an IPv4
packet and an equation for calculating an offset value at which a
length field of the IP packet is located.
[0072] FIG. 41 is a conceptual diagram illustrating a process for
calculating the length of a concatenated packet including an IPv6
packet and an equation for calculating an offset value at which a
length field of the IP packet is located.
[0073] FIG. 42 is a conceptual diagram illustrating an
encapsulation process of a segmented packet according to an
embodiment of the present invention.
[0074] FIG. 43 is a conceptual diagram illustrating a segmentation
process of an IP packet and header information of a link layer
packet according to an embodiment of the present invention.
[0075] FIG. 44 is a conceptual diagram illustrating a segmentation
process of an IP packet including a cyclic redundancy check (CRC)
according to an embodiment of the present invention.
[0076] FIG. 45 is a conceptual diagram illustrating a header
structure of a link layer packet when MPEG-2 TS (Transport Stream)
is input to a link layer according to an embodiment of the present
invention.
[0077] FIG. 46 shows the number of MPEG-2 TS packets contained in a
payload of the link layer packet according to values of a count
field.
[0078] FIG. 47 is a conceptual diagram illustrating a header of the
MPEG-2 TS packet according to an embodiment of the present
invention.
[0079] FIG. 48 is a conceptual diagram illustrating a process for
allowing a transceiver to change a usage of a transport error
indicator field according to an embodiment of the present
invention.
[0080] FIG. 49 is a conceptual diagram illustrating an
encapsulation process of the MPEG-2 TS packet according to an
embodiment of the present invention.
[0081] FIG. 50 is a conceptual diagram illustrating an
encapsulation process of the MPEG-2 TS packet having the same PID
according to an embodiment of the present invention.
[0082] FIG. 51 is a conceptual diagram illustrating an equation for
calculating the length of a link layer packet through a Common PID
reduction process and a Common PID reduction process.
[0083] FIG. 52 is a conceptual diagram illustrating the number of
concatenated MPEG-2 TS packets and the length of a link layer
packet according to count field values when Common PID reduction is
used.
[0084] FIG. 53 is a conceptual diagram illustrating a process for
encapsulating the MPEG-2 TS packet including a null packet
according to an embodiment of the present invention.
[0085] FIG. 54 is a conceptual diagram illustrating a step for
processing an indicator configured to count a removed null packet
and an equation for calculating the length of a link layer packet
in the processing step.
[0086] FIG. 55 is a conceptual diagram illustrating a process for
encapsulating the MPEG-2 TS packet including a null packet
according to another embodiment of the present invention.
[0087] FIG. 56 is a conceptual diagram illustrating a process for
encapsulating the MPEG-2 TS packets including the same packet
identifiers (PIDs) in a stream including a null packet according to
an embodiment of the present invention.
[0088] FIG. 57 is a conceptual diagram illustrating an equation for
calculating the length of a link layer packet when the MPEG-2 TS
packets having the same PIDs are encapsulated in a stream including
a null packet according to an embodiment of the present
invention.
[0089] FIG. 58 is a conceptual diagram illustrating a link layer
packet structure for transmitting signaling information according
to an embodiment of the present invention.
[0090] FIG. 59 is a conceptual diagram illustrating a link layer
packet structure for transmitting the framed packet according to an
embodiment of the present invention.
[0091] FIG. 60 shows a syntax of the framed packet according to an
embodiment of the present invention.
[0092] FIG. 61 is a block diagram illustrating a receiver of the
next generation broadcast system according to an embodiment of the
present invention.
[0093] FIG. 62 is a conceptual diagram illustrating a general
format of a section table according to an embodiment of the present
invention.
[0094] FIG. 63 is a conceptual diagram illustrating a link layer
packet for transmitting signaling information according to an
embodiment of the present invention.
[0095] FIG. 64 shows the meaning of values denoted by the signaling
type field, and contents of a fixed header and an extended header
located behind the signaling type field.
[0096] FIG. 65 shows the number of descriptors contained in payload
of the link layer packet according to a concatenation count field
value according to an embodiment of the present invention.
[0097] FIG. 66 is a conceptual diagram illustrating a process for
encapsulating the section table into payload when signaling
information input to the payload of the link layer packet is a
section table.
[0098] FIG. 67 is a conceptual diagram illustrating a syntax of a
network information table (NIT) according to an embodiment of the
present invention.
[0099] FIG. 68 is a conceptual diagram illustrating a syntax of a
delivery system descriptor contained in a network information table
(NIT) according to an embodiment of the present invention.
[0100] FIG. 69 is a conceptual diagram illustrating a syntax of a
fast information table (FTT) according to an embodiment of the
present invention.
[0101] FIG. 70 is a conceptual diagram illustrating a process for
encapsulating a descriptor into payload when signaling information
input to payload of the link layer packet is a descriptor.
[0102] FIG. 71 is a conceptual diagram illustrating a syntax of a
fast information descriptor according to an embodiment of the
present invention.
[0103] FIG. 72 is a conceptual diagram illustrating a delivery
system descriptor according to an embodiment of the present
invention.
[0104] FIG. 73 is a conceptual diagram illustrating a process for
encapsulating one GSE-LLC datum into payload of one link layer
packet when signaling information input to payload of the link
layer packet has a GSE-LLC format used in DVB-GSE.
[0105] FIG. 74 is a conceptual diagram illustrating a process for
encapsulating one GSE-LLC datum into payload of several link layer
packets when signaling information input to payload of the link
layer packet has a GSE-LLC format used in a DVB-GSE standard.
[0106] FIG. 75 illustrates a header of a link layer packet for
Robust Header Compression (RoHC) transmission according to the
present invention.
[0107] FIG. 76 illustrates Embodiment #1 of a method of
transmitting an RoHC packet using a link layer packet, according to
the present invention.
[0108] FIG. 77 illustrates Embodiment #2 of a method of
transmitting an RoHC packet using a link layer packet, according to
the present invention.
[0109] FIG. 78 illustrates Embodiment #3 of a method of
transmitting an RoHC packet using a link layer packet, according to
the present invention.
[0110] FIG. 79 illustrates Embodiment #4 of a method of
transmitting an RoHC packet using a link layer packet, according to
the present invention.
[0111] FIG. 80 illustrates a header of a link layer packet for RoHC
transmission according to an embodiment of the present invention
when an MTU is 1,500.
[0112] FIG. 81 illustrates Embodiment #1 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500 according to the present invention.
[0113] FIG. 82 illustrates Embodiment #2 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500 according to the present invention.
[0114] FIG. 83 illustrates Embodiment #3 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500 according to the present invention.
[0115] FIG. 84 illustrates Embodiment #4 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500 according to the present invention.
[0116] FIG. 85 illustrates Embodiment #5 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500, according to the present invention.
[0117] FIG. 86 illustrates Embodiment #6 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500, according to the present invention.
[0118] FIG. 87 illustrates Embodiment #7 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500, according to the present invention.
[0119] FIG. 88 illustrates a protocol stack for a hybrid-based next
generation broadcast system according to another embodiment of the
present invention.
[0120] FIG. 89 illustrates an operation in a normal mode
corresponding to one of operation modes of a link layer according
to an embodiment of the present invention.
[0121] FIG. 90 illustrates an operation in a transparent mode
corresponding to one of operation modes of a link layer according
to an embodiment of the present invention.
[0122] FIG. 91 illustrates a configuration of a link layer at a
transmitter according to an embodiment of the present invention
(normal mode).
[0123] FIG. 92 illustrates a configuration of a link layer at a
receiver according to an embodiment of the present invention
(normal mode).
[0124] FIG. 93 illustrates a method of transmitting broadcast
signals according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0125] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. The detailed description,
which will be given below with reference to the accompanying
drawings, is intended to explain exemplary embodiments of the
present invention, rather than to show the only embodiments that
can be implemented according to the present invention. The
following detailed description includes specific details in order
to provide a thorough understanding of the present invention.
However, it will be apparent to those skilled in the art that the
present invention may be practiced without such specific
details.
[0126] Although most terms used in the present invention have been
selected from general ones widely used in the art, some terms have
been arbitrarily selected by the applicant and their meanings are
explained in detail in the following description as needed. Thus,
the present invention should be understood based upon the intended
meanings of the terms rather than their simple names or
meanings.
[0127] The present invention provides apparatuses and methods for
transmitting and receiving broadcast signals for future broadcast
services. Future broadcast services according to an embodiment of
the present invention include a terrestrial broadcast service, a
mobile broadcast service, a UHDTV service, etc. The present
invention may process broadcast signals for the future broadcast
services through non-MIMO (Multiple Input Multiple Output) or MIMO
according to one embodiment. A non-MIMO scheme according to an
embodiment of the present invention may include a MISO (Multiple
Input Single Output) scheme, a SISO (Single Input Single Output)
scheme, etc.
[0128] While MISO or MIMO uses two antennas in the following for
convenience of description, the present invention is applicable to
systems using two or more antennas.
[0129] The present invention may defines three physical layer (PL)
profiles (base, handheld and advanced profiles), each optimized to
minimize receiver complexity while attaining the performance
required for a particular use case. The physical layer (PHY)
profiles are subsets of all configurations that a corresponding
receiver should implement.
[0130] The three PHY profiles share most of the functional blocks
but differ slightly in specific blocks and/or parameters.
Additional PHY profiles can be defined in the future. For the
system evolution, future profiles can also be multiplexed with the
existing profiles in a single RF channel through a future extension
frame (FEF). The details of each PHY profile are described
below.
[0131] 1. Base Profile
[0132] The base profile represents a main use case for fixed
receiving devices that are usually connected to a roof-top antenna.
The base profile also includes portable devices that could be
transported to a place but belong to a relatively stationary
reception category. Use of the base profile could be extended to
handheld devices or even vehicular by some improved
implementations, but those use cases are not expected for the base
profile receiver operation.
[0133] Target SNR range of reception is from approximately 10 to 20
dB, which includes the 15 dB SNR reception capability of the
existing broadcast system (e.g. ATSC A/53). The receiver complexity
and power consumption is not as critical as in the battery-operated
handheld devices, which will use the handheld profile. Key system
parameters for the base profile are listed in below table 1.
TABLE-US-00001 TABLE 1 LDPC codeword length 16K, 64K bits
Constellation size 4~10 bpcu (bits per channel use) Time
de-interleaving memory size .ltoreq.2.sup.19 data cells Pilot
patterns Pilot pattern for fixed reception FFT size 16K, 32K
points
[0134] 2. Handheld Profile
[0135] The handheld profile is designed for use in handheld and
vehicular devices that operate with battery power. The devices can
be moving with pedestrian or vehicle speed. The power consumption
as well as the receiver complexity is very important for the
implementation of the devices of the handheld profile. The target
SNR range of the handheld profile is approximately 0 to 10 dB, but
can be configured to reach below 0 dB when intended for deeper
indoor reception.
[0136] In addition to low SNR capability, resilience to the Doppler
Effect caused by receiver mobility is the most important
performance attribute of the handheld profile. Key system
parameters for the handheld profile are listed in the below table
2.
TABLE-US-00002 TABLE 2 LDPC codeword length 16K bits Constellation
size 2~8 bpcu Time de-interleaving memory size .ltoreq.2.sup.18
data cells Pilot patterns Pilot patterns for mobile and indoor
reception FFT size 8K, 16K points
[0137] 3. Advanced Profile
[0138] The advanced profile provides highest channel capacity at
the cost of more implementation complexity. This profile requires
using MIMO transmission and reception, and UHDTV service is a
target use case for which this profile is specifically designed.
The increased capacity can also be used to allow an increased
number of services in a given bandwidth, e.g., multiple SDTV or
HDTV services.
[0139] The target SNR range of the advanced profile is
approximately 20 to 30 dB. MIMO transmission may initially use
existing elliptically-polarized transmission equipment, with
extension to full-power cross-polarized transmission in the future.
Key system parameters for the advanced profile are listed in below
table 3.
TABLE-US-00003 TABLE 3 LDPC codeword length 16K, 64K bits
Constellation size 8~12 bpcu Time de-interleaving memory size
.ltoreq.2.sup.19 data cells Pilot patterns Pilot pattern for fixed
reception FFT size 16K, 32K points
[0140] In this case, the base profile can be used as a profile for
both the terrestrial broadcast service and the mobile broadcast
service. That is, the base profile can be used to define a concept
of a profile which includes the mobile profile. Also, the advanced
profile can be divided advanced profile for a base profile with
MIMO and advanced profile for a handheld profile with MIMO.
Moreover, the three profiles can be changed according to intention
of the designer.
[0141] The following terms and definitions may apply to the present
invention. The following terms and definitions can be changed
according to design.
[0142] auxiliary stream: sequence of cells carrying data of as yet
undefined modulation and coding, which may be used for future
extensions or as required by broadcasters or network operators
[0143] base data pipe: data pipe that carries service signaling
data
[0144] baseband frame (or BBFRAME): set of Kbch bits which form the
input to one FEC encoding process (BCH and LDPC encoding)
[0145] cell: modulation value that is carried by one carrier of the
OFDM transmission
[0146] coded block: LDPC-encoded block of PLS1 data or one of the
LDPC-encoded blocks of PLS2 data
[0147] data pipe: logical channel in the physical layer that
carries service data or related metadata, which may carry one or
multiple service(s) or service component(s).
[0148] data pipe unit: a basic unit for allocating data cells to a
DP in a frame.
[0149] data symbol: OFDM symbol in a frame which is not a preamble
symbol (the frame signaling symbol and frame edge symbol is
included in the data symbol)
[0150] DP_ID: this 8-bit field identifies uniquely a DP within the
system identified by the SYSTEM_ID
[0151] dummy cell: cell carrying a pseudo-random value used to fill
the remaining capacity not used for PLS signaling, DPs or auxiliary
streams
[0152] emergency alert channel: part of a frame that carries EAS
information data
[0153] frame: physical layer time slot that starts with a preamble
and ends with a frame edge symbol
[0154] frame repetition unit: a set of frames belonging to same or
different physical layer profile including a FEF, which is repeated
eight times in a super-frame
[0155] fast information channel: a logical channel in a frame that
carries the mapping information between a service and the
corresponding base DP
[0156] FECBLOCK: set of LDPC-encoded bits of a DP data
[0157] FFT size: nominal FFT size used for a particular mode, equal
to the active symbol period Ts expressed in cycles of the
elementary period T
[0158] frame signaling symbol: OFDM symbol with higher pilot
density used at the start of a frame in certain combinations of FFT
size, guard interval and scattered pilot pattern, which carries a
part of the PLS data
[0159] frame edge symbol: OFDM symbol with higher pilot density
used at the end of a frame in certain combinations of FFT size,
guard interval and scattered pilot pattern
[0160] frame-group: the set of all the frames having the same PHY
profile type in a super-frame.
[0161] future extension frame: physical layer time slot within the
super-frame that could be used for future extension, which starts
with a preamble
[0162] Futurecast UTB system: proposed physical layer broadcasting
system, of which the input is one or more MPEG2-TS or IP or general
stream(s) and of which the output is an RF signal
[0163] input stream: A stream of data for an ensemble of services
delivered to the end users by the system.
[0164] normal data symbol: data symbol excluding the frame
signaling symbol and the frame edge symbol
[0165] PHY profile: subset of all configurations that a
corresponding receiver should implement
[0166] PLS: physical layer signaling data consisting of PLS1 and
PLS2
[0167] PLS1: a first set of PLS data carried in the FSS symbols
having a fixed size, coding and modulation, which carries basic
information about the system as well as the parameters needed to
decode the PLS2
[0168] NOTE: PLS1 data remains constant for the duration of a
frame-group.
[0169] PLS2: a second set of PLS data transmitted in the FSS
symbol, which carries more detailed PLS data about the system and
the DPs
[0170] PLS2 dynamic data: PLS2 data that may dynamically change
frame-by-frame
[0171] PLS2 static data: PLS2 data that remains static for the
duration of a frame-group
[0172] preamble signaling data: signaling data carried by the
preamble symbol and used to identify the basic mode of the
system
[0173] preamble symbol: fixed-length pilot symbol that carries
basic PLS data and is located in the beginning of a frame
[0174] NOTE: The preamble symbol is mainly used for fast initial
band scan to detect the system signal, its timing, frequency
offset, and FFT-size.
[0175] reserved for future use: not defined by the present document
but may be defined in future
[0176] super-frame: set of eight frame repetition units
[0177] time interleaving block (TI block): set of cells within
which time interleaving is carried out, corresponding to one use of
the time interleaver memory
[0178] TI group: unit over which dynamic capacity allocation for a
particular DP is carried out, made up of an integer, dynamically
varying number of XFECBLOCKs.
[0179] NOTE: The TI group may be mapped directly to one frame or
may be mapped to multiple frames. It may contain one or more TI
blocks.
[0180] Type 1 DP: DP of a frame where all DPs are mapped into the
frame in TDM fashion
[0181] Type 2 DP: DP of a frame where all DPs are mapped into the
frame in FDM fashion
[0182] XFECBLOCK: set of Ncells cells carrying all the bits of one
LDPC FECBLOCK
[0183] FIG. 1 illustrates a structure of an apparatus for
transmitting broadcast signals for future broadcast services
according to an embodiment of the present invention.
[0184] The apparatus for transmitting broadcast signals for future
broadcast services according to an embodiment of the present
invention can include an input formatting block 1000, a BICM (Bit
interleaved coding & modulation) block 1010, a frame structure
block 1020, an OFDM (Orthogonal Frequency Division Multiplexing)
generation block 1030 and a signaling generation block 1040. A
description will be given of the operation of each module of the
apparatus for transmitting broadcast signals.
[0185] IP stream/packets and MPEG2-TS are the main input formats,
other stream types are handled as General Streams. In addition to
these data inputs, Management Information is input to control the
scheduling and allocation of the corresponding bandwidth for each
input stream. One or multiple TS stream(s), IP stream(s) and/or
General Stream(s) inputs are simultaneously allowed.
[0186] The input formatting block 1000 can demultiplex each input
stream into one or multiple data pipe(s), to each of which an
independent coding and modulation is applied. The data pipe (DP) is
the basic unit for robustness control, thereby affecting
quality-of-service (QoS). One or multiple service(s) or service
component(s) can be carried by a single DP. Details of operations
of the input formatting block 1000 will be described later.
[0187] The data pipe is a logical channel in the physical layer
that carries service data or related metadata, which may carry one
or multiple service(s) or service component(s).
[0188] Also, the data pipe unit: a basic unit for allocating data
cells to a DP in a frame.
[0189] In the BICM block 1010, parity data is added for error
correction and the encoded bit streams are mapped to complex-value
constellation symbols. The symbols are interleaved across a
specific interleaving depth that is used for the corresponding DP.
For the advanced profile, MIMO encoding is performed in the BICM
block 1010 and the additional data path is added at the output for
MIMO transmission. Details of operations of the BICM block 1010
will be described later.
[0190] The Frame Building block 1020 can map the data cells of the
input DPs into the OFDM symbols within a frame. After mapping, the
frequency interleaving is used for frequency-domain diversity,
especially to combat frequency-selective fading channels. Details
of operations of the Frame Building block 1020 will be described
later.
[0191] After inserting a preamble at the beginning of each frame,
the OFDM Generation block 1030 can apply conventional OFDM
modulation having a cyclic prefix as guard interval. For antenna
space diversity, a distributed MISO scheme is applied across the
transmitters. In addition, a Peak-to-Average Power Reduction (PAPR)
scheme is performed in the time domain. For flexible network
planning, this proposal provides a set of various FFT sizes, guard
interval lengths and corresponding pilot patterns. Details of
operations of the OFDM Generation block 1030 will be described
later.
[0192] The Signaling Generation block 1040 can create physical
layer signaling information used for the operation of each
functional block. This signaling information is also transmitted so
that the services of interest are properly recovered at the
receiver side. Details of operations of the Signaling Generation
block 1040 will be described later.
[0193] FIGS. 2, 3 and 4 illustrate the input formatting block 1000
according to embodiments of the present invention. A description
will be given of each figure.
[0194] FIG. 2 illustrates an input formatting block according to
one embodiment of the present invention. FIG. 2 shows an input
formatting module when the input signal is a single input
stream.
[0195] The input formatting block illustrated in FIG. 2 corresponds
to an embodiment of the input formatting block 1000 described with
reference to FIG. 1.
[0196] The input to the physical layer may be composed of one or
multiple data streams. Each data stream is carried by one DP. The
mode adaptation modules slice the incoming data stream into data
fields of the baseband frame (BBF). The system supports three types
of input data streams: MPEG2-TS, Internet protocol (IP) and Generic
stream (GS). MPEG2-TS is characterized by fixed length (188 byte)
packets with the first byte being a sync-byte (0x47). An IP stream
is composed of variable length IP datagram packets, as signaled
within IP packet headers. The system supports both IPv4 and IPv6
for the IP stream. GS may be composed of variable length packets or
constant length packets, signaled within encapsulation packet
headers.
[0197] (a) shows a mode adaptation block 2000 and a stream
adaptation 2010 for signal DP and (b) shows a PLS generation block
2020 and a PLS scrambler 2030 for generating and processing PLS
data. A description will be given of the operation of each
block.
[0198] The Input Stream Splitter splits the input TS, IP, GS
streams into multiple service or service component (audio, video,
etc.) streams. The mode adaptation module 2010 is comprised of a
CRC Encoder, BB (baseband) Frame Slicer, and BB Frame Header
Insertion block.
[0199] The CRC Encoder provides three kinds of CRC encoding for
error detection at the user packet (UP) level, i.e., CRC-8, CRC-16,
and CRC-32. The computed CRC bytes are appended after the UP. CRC-8
is used for TS stream and CRC-32 for IP stream. If the GS stream
doesn't provide the CRC encoding, the proposed CRC encoding should
be applied.
[0200] BB Frame Slicer maps the input into an internal logical-bit
format. The first received bit is defined to be the MSB. The BB
Frame Slicer allocates a number of input bits equal to the
available data field capacity. To allocate a number of input bits
equal to the BBF payload, the UP packet stream is sliced to fit the
data field of BBF.
[0201] BB Frame Header Insertion block can insert fixed length BBF
header of 2 bytes is inserted in front of the BB Frame. The BBF
header is composed of STUFFI (1 bit), SYNCD (13 bits), and RFU (2
bits). In addition to the fixed 2-Byte BBF header, BBF can have an
extension field (1 or 3 bytes) at the end of the 2-byte BBF
header.
[0202] The stream adaptation 2010 is comprised of stuffing
insertion block and BB scrambler.
[0203] The stuffing insertion block can insert stuffing field into
a payload of a BB frame. If the input data to the stream adaptation
is sufficient to fill a BB-Frame, STUFFI is set to `0` and the BBF
has no stuffing field. Otherwise STUFFI is set to `1` and the
stuffing field is inserted immediately after the BBF header. The
stuffing field comprises two bytes of the stuffing field header and
a variable size of stuffing data.
[0204] The BB scrambler scrambles complete BBF for energy
dispersal. The scrambling sequence is synchronous with the BBF. The
scrambling sequence is generated by the feed-back shift
register.
[0205] The PLS generation block 2020 can generate physical layer
signaling (PLS) data. The PLS provides the receiver with a means to
access physical layer DPs. The PLS data consists of PLS1 data and
PLS2 data.
[0206] The PLS1 data is a first set of PLS data carried in the FSS
symbols in the frame having a fixed size, coding and modulation,
which carries basic information about the system as well as the
parameters needed to decode the PLS2 data. The PLS1 data provides
basic transmission parameters including parameters required to
enable the reception and decoding of the PLS2 data. Also, the PLS1
data remains constant for the duration of a frame-group.
[0207] The PLS2 data is a second set of PLS data transmitted in the
FSS symbol, which carries more detailed PLS data about the system
and the DPs. The PLS2 contains parameters that provide sufficient
information for the receiver to decode the desired DP. The PLS2
signaling further consists of two types of parameters, PLS2 Static
data (PLS2-STAT data) and PLS2 dynamic data (PLS2-DYN data). The
PLS2 Static data is PLS2 data that remains static for the duration
of a frame-group and the PLS2 dynamic data is PLS2 data that may
dynamically change frame-by-frame.
[0208] Details of the PLS data will be described later.
[0209] The PLS scrambler 2030 can scramble the generated PLS data
for energy dispersal.
[0210] The above-described blocks may be omitted or replaced by
blocks having similar or identical functions.
[0211] FIG. 3 illustrates an input formatting block according to
another embodiment of the present invention.
[0212] The input formatting block illustrated in FIG. 3 corresponds
to an embodiment of the input formatting block 1000 described with
reference to FIG. 1.
[0213] FIG. 3 shows a mode adaptation block of the input formatting
block when the input signal corresponds to multiple input
streams.
[0214] The mode adaptation block of the input formatting block for
processing the multiple input streams can independently process the
multiple input streams.
[0215] Referring to FIG. 3, the mode adaptation block for
respectively processing the multiple input streams can include an
input stream splitter 3000, an input stream synchronizer 3010, a
compensating delay block 3020, a null packet deletion block 3030, a
head compression block 3040, a CRC encoder 3050, a BB frame slicer
3060 and a BB header insertion block 3070. Description will be
given of each block of the mode adaptation block.
[0216] Operations of the CRC encoder 3050, BB frame slicer 3060 and
BB header insertion block 3070 correspond to those of the CRC
encoder, BB frame slicer and BB header insertion block described
with reference to FIG. 2 and thus description thereof is
omitted.
[0217] The input stream splitter 3000 can split the input TS, IP,
GS streams into multiple service or service component (audio,
video, etc.) streams.
[0218] The input stream synchronizer 3010 may be referred as ISSY.
The ISSY can provide suitable means to guarantee Constant Bit Rate
(CBR) and constant end-to-end transmission delay for any input data
format. The ISSY is always used for the case of multiple DPs
carrying TS, and optionally used for multiple DPs carrying GS
streams.
[0219] The compensating delay block 3020 can delay the split TS
packet stream following the insertion of ISSY information to allow
a TS packet recombining mechanism without requiring additional
memory in the receiver.
[0220] The null packet deletion block 3030, is used only for the TS
input stream case. Some TS input streams or split TS streams may
have a large number of null-packets present in order to accommodate
VBR (variable bit-rate) services in a CBR TS stream. In this case,
in order to avoid unnecessary transmission overhead, null-packets
can be identified and not transmitted. In the receiver, removed
null-packets can be re-inserted in the exact place where they were
originally by reference to a deleted null-packet (DNP) counter that
is inserted in the transmission, thus guaranteeing constant
bit-rate and avoiding the need for time-stamp (PCR) updating.
[0221] The head compression block 3040 can provide packet header
compression to increase transmission efficiency for TS or IP input
streams. Because the receiver can have a priori information on
certain parts of the header, this known information can be deleted
in the transmitter.
[0222] For Transport Stream, the receiver has a-priori information
about the sync-byte configuration (0x47) and the packet length (188
Byte). If the input TS stream carries content that has only one
PID, i.e., for only one service component (video, audio, etc.) or
service sub-component (SVC base layer, SVC enhancement layer, MVC
base view or MVC dependent views), TS packet header compression can
be applied (optionally) to the Transport Stream. IP packet header
compression is used optionally if the input steam is an IP
stream.
[0223] The above-described blocks may be omitted or replaced by
blocks having similar or identical functions.
[0224] FIG. 4 illustrates an input formatting block according to
another embodiment of the present invention.
[0225] The input formatting block illustrated in FIG. 4 corresponds
to an embodiment of the input formatting block 1000 described with
reference to FIG. 1.
[0226] FIG. 4 illustrates a stream adaptation block of the input
formatting module when the input signal corresponds to multiple
input streams.
[0227] Referring to FIG. 4, the mode adaptation block for
respectively processing the multiple input streams can include a
scheduler 4000, an 1-Frame delay block 4010, a stuffing insertion
block 4020, an in-band signaling 4030, a BB Frame scrambler 4040, a
PLS generation block 4050 and a PLS scrambler 4060. Description
will be given of each block of the stream adaptation block.
[0228] Operations of the stuffing insertion block 4020, the BB
Frame scrambler 4040, the PLS generation block 4050 and the PLS
scrambler 4060 correspond to those of the stuffing insertion block,
BB scrambler, PLS generation block and the PLS scrambler described
with reference to FIG. 2 and thus description thereof is
omitted.
[0229] The scheduler 4000 can determine the overall cell allocation
across the entire frame from the amount of FECBLOCKs of each DP.
Including the allocation for PLS, EAC and FIC, the scheduler
generates the values of PLS2-DYN data, which is transmitted as
in-band signaling or PLS cell in FSS of the frame. Details of
FECBLOCK, EAC and FIC will be described later.
[0230] The 1-Frame delay block 4010 can delay the input data by one
transmission frame such that scheduling information about the next
frame can be transmitted through the current frame for in-band
signaling information to be inserted into the DPs.
[0231] The in-band signaling 4030 can insert un-delayed part of the
PLS2 data into a DP of a frame.
[0232] The above-described blocks may be omitted or replaced by
blocks having similar or identical functions.
[0233] FIG. 5 illustrates a BICM block according to an embodiment
of the present invention.
[0234] The BICM block illustrated in FIG. 5 corresponds to an
embodiment of the BICM block 1010 described with reference to FIG.
1.
[0235] As described above, the apparatus for transmitting broadcast
signals for future broadcast services according to an embodiment of
the present invention can provide a terrestrial broadcast service,
mobile broadcast service, UHDTV service, etc.
[0236] Since QoS (quality of service) depends on characteristics of
a service provided by the apparatus for transmitting broadcast
signals for future broadcast services according to an embodiment of
the present invention, data corresponding to respective services
needs to be processed through different schemes. Accordingly, the a
BICM block according to an embodiment of the present invention can
independently process DPs input thereto by independently applying
SISO, MISO and MIMO schemes to the data pipes respectively
corresponding to data paths. Consequently, the apparatus for
transmitting broadcast signals for future broadcast services
according to an embodiment of the present invention can control QoS
for each service or service component transmitted through each
DP.
[0237] (a) shows the BICM block shared by the base profile and the
handheld profile and (b) shows the BICM block of the advanced
profile.
[0238] The BICM block shared by the base profile and the handheld
profile and the BICM block of the advanced profile can include
plural processing blocks for processing each DP.
[0239] A description will be given of each processing block of the
BICM block for the base profile and the handheld profile and the
BICM block for the advanced profile.
[0240] A processing block 5000 of the BICM block for the base
profile and the handheld profile can include a Data FEC encoder
5010, a bit interleaver 5020, a constellation mapper 5030, an SSD
(Signal Space Diversity) encoding block 5040 and a time interleaver
5050.
[0241] The Data FEC encoder 5010 can perform the FEC encoding on
the input BBF to generate FECBLOCK procedure using outer coding
(BCH), and inner coding (LDPC). The outer coding (BCH) is optional
coding method. Details of operations of the Data FEC encoder 5010
will be described later.
[0242] The bit interleaver 5020 can interleave outputs of the Data
FEC encoder 5010 to achieve optimized performance with combination
of the LDPC codes and modulation scheme while providing an
efficiently implementable structure. Details of operations of the
bit interleaver 5020 will be described later.
[0243] The constellation mapper 5030 can modulate each cell word
from the bit interleaver 5020 in the base and the handheld
profiles, or cell word from the Cell-word demultiplexer 5010-1 in
the advanced profile using either QPSK, QAM-16, non-uniform QAM
(NUQ-64, NUQ-256, NUQ-1024) or non-uniform constellation (NUC-16,
NUC-64, NUC-256, NUC-1024) to give a power-normalized constellation
point, el. This constellation mapping is applied only for DPs.
Observe that QAM-16 and NUQs are square shaped, while NUCs have
arbitrary shape. When each constellation is rotated by any multiple
of 90 degrees, the rotated constellation exactly overlaps with its
original one. This "rotation-sense" symmetric property makes the
capacities and the average powers of the real and imaginary
components equal to each other. Both NUQs and NUCs are defined
specifically for each code rate and the particular one used is
signaled by the parameter DP_MOD filed in PLS2 data.
[0244] The SSD encoding block 5040 can precode cells in two (2D),
three (3D), and four (4D) dimensions to increase the reception
robustness under difficult fading conditions.
[0245] The time interleaver 5050 can operates at the DP level. The
parameters of time interleaving (TI) may be set differently for
each DP. Details of operations of the time interleaver 5050 will be
described later.
[0246] A processing block 5000-1 of the BICM block for the advanced
profile can include the Data FEC encoder, bit interleaver,
constellation mapper, and time interleaver. However, the processing
block 5000-1 is distinguished from the processing block 5000
further includes a cell-word demultiplexer 5010-1 and a MIMO
encoding block 5020-1.
[0247] Also, the operations of the Data FEC encoder, bit
interleaver, constellation mapper, and time interleaver in the
processing block 5000-1 correspond to those of the Data FEC encoder
5010, bit interleaver 5020, constellation mapper 5030, and time
interleaver 5050 described and thus description thereof is
omitted.
[0248] The cell-word demultiplexer 5010-1 is used for the DP of the
advanced profile to divide the single cell-word stream into dual
cell-word streams for MIMO processing. Details of operations of the
cell-word demultiplexer 5010-1 will be described later.
[0249] The MIMO encoding block 5020-1 can processing the output of
the cell-word demultiplexer 5010-1 using MIMO encoding scheme. The
MIMO encoding scheme was optimized for broadcasting signal
transmission. The MIMO technology is a promising way to get a
capacity increase but it depends on channel characteristics.
Especially for broadcasting, the strong LOS component of the
channel or a difference in the received signal power between two
antennas caused by different signal propagation characteristics
makes it difficult to get capacity gain from MIMO. The proposed
MIMO encoding scheme overcomes this problem using a rotation-based
pre-coding and phase randomization of one of the MIMO output
signals.
[0250] MIMO encoding is intended for a 2.times.2 MIMO system
requiring at least two antennas at both the transmitter and the
receiver. Two MIMO encoding modes are defined in this proposal;
full-rate spatial multiplexing (FR-SM) and full-rate full-diversity
spatial multiplexing (FRFD-SM). The FR-SM encoding provides
capacity increase with relatively small complexity increase at the
receiver side while the FRFD-SM encoding provides capacity increase
and additional diversity gain with a great complexity increase at
the receiver side. The proposed MIMO encoding scheme has no
restriction on the antenna polarity configuration.
[0251] MIMO processing is required for the advanced profile frame,
which means all DPs in the advanced profile frame are processed by
the MIMO encoder. MIMO processing is applied at DP level. Pairs of
the Constellation Mapper outputs NUQ (e1,i and e2,i) are fed to the
input of the MIMO Encoder. Paired MIMO Encoder output (g1,i and
g2,i) is transmitted by the same carrier k and OFDM symbol 1 of
their respective TX antennas.
[0252] The above-described blocks may be omitted or replaced by
blocks having similar or identical functions.
[0253] FIG. 6 illustrates a BICM block according to another
embodiment of the present invention.
[0254] The BICM block illustrated in FIG. 6 corresponds to an
embodiment of the BICM block 1010 described with reference to FIG.
1.
[0255] FIG. 6 illustrates a BICM block for protection of physical
layer signaling (PLS), emergency alert channel (EAC) and fast
information channel (FIC). EAC is a part of a frame that carries
EAS information data and FIC is a logical channel in a frame that
carries the mapping information between a service and the
corresponding base DP. Details of the EAC and FIC will be described
later.
[0256] Referring to FIG. 6, the BICM block for protection of PLS,
EAC and FIC can include a PLS FEC encoder 6000, a bit interleaver
6010, and a constellation mapper 6020.
[0257] Also, the PLS FEC encoder 6000 can include a scrambler, BCH
encoding/zero insertion block, LDPC encoding block and LDPC parity
punturing block. Description will be given of each block of the
BICM block.
[0258] The PLS FEC encoder 6000 can encode the scrambled PLS 1/2
data, EAC and FIC section.
[0259] The scrambler can scramble PLS1 data and PLS2 data before
BCH encoding and shortened and punctured LDPC encoding.
[0260] The BCH encoding/zero insertion block can perform outer
encoding on the scrambled PLS 1/2 data using the shortened BCH code
for PLS protection and insert zero bits after the BCH encoding. For
PLS1 data only, the output bits of the zero insertion may be
permuted before LDPC encoding.
[0261] The LDPC encoding block can encode the output of the BCH
encoding/zero insertion block using LDPC code. To generate a
complete coded block, Cldpc, parity bits, Pldpc are encoded
systematically from each zero-inserted PLS information block, Ildpc
and appended after it.
C.sub.ldpc=[I.sub.ldpcP.sub.ldpc]=[i.sub.0,i.sub.1, . . .
i.sub.K.sub.ldpc.sub.-1,p.sub.0,p.sub.1, . . .
,p.sub.N.sub.ldpc.sub.-K.sub.ldpc.sub.-1] [Math FIG. 1]
[0262] The LDPC code parameters for PLS1 and PLS2 are as following
table 4.
TABLE-US-00004 TABLE 4 Signaling K.sub.ldpc code Type K.sub.sig
K.sub.bch N.sub.bch.sub.--.sub.parity (=N.sub.bch) N.sub.ldpc
N.sub.ldpc.sub.--.sub.parity rate Q.sub.ldpc PLS1 342 1020 60 1080
4320 3240 1/4 36 PLS2 <1021 >1020 2100 2160 7200 5040 3/10
56
[0263] The LDPC parity punturing block can perform puncturing on
the PLS1 data and PLS 2 data.
[0264] When shortening is applied to the PLS1 data protection, some
LDPC parity bits are punctured after LDPC encoding. Also, for the
PLS2 data protection, the LDPC parity bits of PLS2 are punctured
after LDPC encoding. These punctured bits are not transmitted.
[0265] The bit interleaver 6010 can interleave the each shortened
and punctured PLS1 data and PLS2 data.
[0266] The constellation mapper 6020 can map the bit interleaved
PLS1 data and PLS2 data onto constellations.
[0267] The above-described blocks may be omitted or replaced by
blocks having similar or identical functions.
[0268] FIG. 7 illustrates a frame building block according to one
embodiment of the present invention.
[0269] The frame building block illustrated in FIG. 7 corresponds
to an embodiment of the frame building block 1020 described with
reference to FIG. 1.
[0270] Referring to FIG. 7, the frame building block can include a
delay compensation block 7000, a cell mapper 7010 and a frequency
interleaver 7020. Description will be given of each block of the
frame building block.
[0271] The delay compensation block 7000 can adjust the timing
between the data pipes and the corresponding PLS data to ensure
that they are co-timed at the transmitter end. The PLS data is
delayed by the same amount as data pipes are by addressing the
delays of data pipes caused by the Input Formatting block and BICM
block. The delay of the BICM block is mainly due to the time
interleaver. In-band signaling data carries information of the next
TI group so that they are carried one frame ahead of the DPs to be
signaled. The Delay Compensating block delays in-band signaling
data accordingly.
[0272] The cell mapper 7010 can map PLS, EAC, FIC, DPs, auxiliary
streams and dummy cells into the active carriers of the OFDM
symbols in the frame. The basic function of the cell mapper 7010 is
to map data cells produced by the TIs for each of the DPs, PLS
cells, and EAC/FIC cells, if any, into arrays of active OFDM cells
corresponding to each of the OFDM symbols within a frame. Service
signaling data (such as PSI (program specific information)/SI) can
be separately gathered and sent by a data pipe. The Cell Mapper
operates according to the dynamic information produced by the
scheduler and the configuration of the frame structure. Details of
the frame will be described later.
[0273] The frequency interleaver 7020 can randomly interleave data
cells received from the cell mapper 7010 to provide frequency
diversity. Also, the frequency interleaver 7020 can operate on very
OFDM symbol pair comprised of two sequential OFDM symbols using a
different interleaving-seed order to get maximum interleaving gain
in a single frame.
[0274] The above-described blocks may be omitted or replaced by
blocks having similar or identical functions.
[0275] FIG. 8 illustrates an OFDM generation block according to an
embodiment of the present invention.
[0276] The OFDM generation block illustrated in FIG. 8 corresponds
to an embodiment of the OFDM generation block 1030 described with
reference to FIG. 1.
[0277] The OFDM generation block modulates the OFDM carriers by the
cells produced by the Frame Building block, inserts the pilots, and
produces the time domain signal for transmission. Also, this block
subsequently inserts guard intervals, and applies PAPR
(Peak-to-Average Power Radio) reduction processing to produce the
final RF signal.
[0278] Referring to FIG. 8, the frame building block can include a
pilot and reserved tone insertion block 8000, a 2D-eSFN encoding
block 8010, an IFFT (Inverse Fast Fourier Transform) block 8020, a
PAPR reduction block 8030, a guard interval insertion block 8040, a
preamble insertion block 8050, other system insertion block 8060
and a DAC block 8070. Description will be given of each block of
the frame building block.
[0279] The pilot and reserved tone insertion block 8000 can insert
pilots and the reserved tone.
[0280] Various cells within the OFDM symbol are modulated with
reference information, known as pilots, which have transmitted
values known a priori in the receiver. The information of pilot
cells is made up of scattered pilots, continual pilots, edge
pilots, FSS (frame signaling symbol) pilots and FES (frame edge
symbol) pilots. Each pilot is transmitted at a particular boosted
power level according to pilot type and pilot pattern. The value of
the pilot information is derived from a reference sequence, which
is a series of values, one for each transmitted carrier on any
given symbol. The pilots can be used for frame synchronization,
frequency synchronization, time synchronization, channel
estimation, and transmission mode identification, and also can be
used to follow the phase noise.
[0281] Reference information, taken from the reference sequence, is
transmitted in scattered pilot cells in every symbol except the
preamble, FSS and FES of the frame. Continual pilots are inserted
in every symbol of the frame. The number and location of continual
pilots depends on both the FFT size and the scattered pilot
pattern. The edge carriers are edge pilots in every symbol except
for the preamble symbol. They are inserted in order to allow
frequency interpolation up to the edge of the spectrum. FSS pilots
are inserted in FSS(s) and FES pilots are inserted in FES. They are
inserted in order to allow time interpolation up to the edge of the
frame.
[0282] The system according to an embodiment of the present
invention supports the SFN network, where distributed MISO scheme
is optionally used to support very robust transmission mode. The
2D-eSFN is a distributed MISO scheme that uses multiple TX
antennas, each of which is located in the different transmitter
site in the SFN network.
[0283] The 2D-eSFN encoding block 8010 can process a 2D-eSFN
processing to distorts the phase of the signals transmitted from
multiple transmitters, in order to create both time and frequency
diversity in the SFN configuration. Hence, burst errors due to low
flat fading or deep-fading for a long time can be mitigated.
[0284] The IFFT block 8020 can modulate the output from the 2D-eSFN
encoding block 8010 using OFDM modulation scheme. Any cell in the
data symbols which has not been designated as a pilot (or as a
reserved tone) carries one of the data cells from the frequency
interleaver. The cells are mapped to OFDM carriers.
[0285] The PAPR reduction block 8030 can perform a PAPR reduction
on input signal using various PAPR reduction algorithm in the time
domain.
[0286] The guard interval insertion block 8040 can insert guard
intervals and the preamble insertion block 8050 can insert preamble
in front of the signal. Details of a structure of the preamble will
be described later. The other system insertion block 8060 can
multiplex signals of a plurality of broadcast
transmission/reception systems in the time domain such that data of
two or more different broadcast transmission/reception systems
providing broadcast services can be simultaneously transmitted in
the same RF signal bandwidth. In this case, the two or more
different broadcast transmission/reception systems refer to systems
providing different broadcast services. The different broadcast
services may refer to a terrestrial broadcast service, mobile
broadcast service, etc. Data related to respective broadcast
services can be transmitted through different frames.
[0287] The DAC block 8070 can convert an input digital signal into
an analog signal and output the analog signal. The signal output
from the DAC block 7800 can be transmitted through multiple output
antennas according to the physical layer profiles. A Tx antenna
according to an embodiment of the present invention can have
vertical or horizontal polarity.
[0288] The above-described blocks may be omitted or replaced by
blocks having similar or identical functions according to
design.
[0289] FIG. 9 illustrates a structure of an apparatus for receiving
broadcast signals for future broadcast services according to an
embodiment of the present invention.
[0290] The apparatus for receiving broadcast signals for future
broadcast services according to an embodiment of the present
invention can correspond to the apparatus for transmitting
broadcast signals for future broadcast services, described with
reference to FIG. 1
[0291] The apparatus for receiving broadcast signals for future
broadcast services according to an embodiment of the present
invention can include a synchronization & demodulation module
9000, a frame parsing module 9010, a demapping & decoding
module 9020, an output processor 9030 and a signaling decoding
module 9040. A description will be given of operation of each
module of the apparatus for receiving broadcast signals.
[0292] The synchronization & demodulation module 9000 can
receive input signals through m Rx antennas, perform signal
detection and synchronization with respect to a system
corresponding to the apparatus for receiving broadcast signals and
carry out demodulation corresponding to a reverse procedure of the
procedure performed by the apparatus for transmitting broadcast
signals.
[0293] The frame parsing module 9100 can parse input signal frames
and extract data through which a service selected by a user is
transmitted. If the apparatus for transmitting broadcast signals
performs interleaving, the frame parsing module 9100 can carry out
deinterleaving corresponding to a reverse procedure of
interleaving. In this case, the positions of a signal and data that
need to be extracted can be obtained by decoding data output from
the signaling decoding module 9400 to restore scheduling
information generated by the apparatus for transmitting broadcast
signals.
[0294] The demapping & decoding module 9200 can convert the
input signals into bit domain data and then deinterleave the same
as necessary. The demapping & decoding module 9200 can perform
demapping for mapping applied for transmission efficiency and
correct an error generated on a transmission channel through
decoding. In this case, the demapping & decoding module 9200
can obtain transmission parameters necessary for demapping and
decoding by decoding the data output from the signaling decoding
module 9400.
[0295] The output processor 9300 can perform reverse procedures of
various compression/signal processing procedures which are applied
by the apparatus for transmitting broadcast signals to improve
transmission efficiency. In this case, the output processor 9300
can acquire necessary control information from data output from the
signaling decoding module 9400. The output of the output processor
8300 corresponds to a signal input to the apparatus for
transmitting broadcast signals and may be MPEG-TSs, IP streams (v4
or v6) and generic streams.
[0296] The signaling decoding module 9400 can obtain PLS
information from the signal demodulated by the synchronization
& demodulation module 9000. As described above, the frame
parsing module 9100, demapping & decoding module 9200 and
output processor 9300 can execute functions thereof using the data
output from the signaling decoding module 9400.
[0297] FIG. 10 illustrates a frame structure according to an
embodiment of the present invention.
[0298] FIG. 10 shows an example configuration of the frame types
and FRUs in a super-frame. (a) shows a super frame according to an
embodiment of the present invention, (b) shows FRU (Frame
Repetition Unit) according to an embodiment of the present
invention, (c) shows frames of variable PHY profiles in the FRU and
(d) shows a structure of a frame.
[0299] A super-frame may be composed of eight FRUs. The FRU is a
basic multiplexing unit for TDM of the frames, and is repeated
eight times in a super-frame.
[0300] Each frame in the FRU belongs to one of the PHY profiles,
(base, handheld, advanced) or FEF. The maximum allowed number of
the frames in the FRU is four and a given PHY profile can appear
any number of times from zero times to four times in the FRU (e.g.,
base, base, handheld, advanced). PHY profile definitions can be
extended using reserved values of the PHY_PROFILE in the preamble,
if required.
[0301] The FEF part is inserted at the end of the FRU, if included.
When the FEF is included in the FRU, the minimum number of FEFs is
8 in a super-frame. It is not recommended that FEF parts be
adjacent to each other.
[0302] One frame is further divided into a number of OFDM symbols
and a preamble. As shown in (d), the frame comprises a preamble,
one or more frame signaling symbols (FSS), normal data symbols and
a frame edge symbol (FES).
[0303] The preamble is a special symbol that enables fast
Futurecast UTB system signal detection and provides a set of basic
transmission parameters for efficient transmission and reception of
the signal. The detailed description of the preamble will be will
be described later.
[0304] The main purpose of the FSS(s) is to carry the PLS data. For
fast synchronization and channel estimation, and hence fast
decoding of PLS data, the FSS has more dense pilot pattern than the
normal data symbol. The FES has exactly the same pilots as the FSS,
which enables frequency-only interpolation within the FES and
temporal interpolation, without extrapolation, for symbols
immediately preceding the FES.
[0305] FIG. 11 illustrates a signaling hierarchy structure of the
frame according to an embodiment of the present invention.
[0306] FIG. 11 illustrates the signaling hierarchy structure, which
is split into three main parts: the preamble signaling data 11000,
the PLS1 data 11010 and the PLS2 data 11020. The purpose of the
preamble, which is carried by the preamble symbol in every frame,
is to indicate the transmission type and basic transmission
parameters of that frame. The PLS1 enables the receiver to access
and decode the PLS2 data, which contains the parameters to access
the DP of interest. The PLS2 is carried in every frame and split
into two main parts: PLS2-STAT data and PLS2-DYN data. The static
and dynamic portion of PLS2 data is followed by padding, if
necessary.
[0307] FIG. 12 illustrates preamble signaling data according to an
embodiment of the present invention.
[0308] Preamble signaling data carries 21 bits of information that
are needed to enable the receiver to access PLS data and trace DPs
within the frame structure. Details of the preamble signaling data
are as follows:
[0309] PHY_PROFILE: This 3-bit field indicates the PHY profile type
of the current frame. The mapping of different PHY profile types is
given in below table 5.
TABLE-US-00005 TABLE 5 Value PHY profile 000 Base profile 001
Handheld profile 010 Advanced profiled 011~110 Reserved 111 FEF
[0310] FFT_SIZE: This 2 bit field indicates the FFT size of the
current frame within a frame-group, as described in below table
6.
TABLE-US-00006 TABLE 6 Value FFT size 00 8K FFT 01 16K FFT 10 32K
FFT 11 Reserved
[0311] GI_FRACTION: This 3 bit field indicates the guard interval
fraction value in the current super-frame, as described in below
table 7.
TABLE-US-00007 TABLE 7 Value GI_FRACTION 000 1/5 001 1/10 010 1/20
011 1/40 100 1/80 101 1/160 110-111 Reserved
[0312] EAC_FLAG: This 1 bit field indicates whether the EAC is
provided in the current frame. If this field is set to `1`,
emergency alert service (EAS) is provided in the current frame. If
this field set to `0`, EAS is not carried in the current frame.
This field can be switched dynamically within a super-frame.
[0313] PILOT_MODE: This 1-bit field indicates whether the pilot
mode is mobile mode or fixed mode for the current frame in the
current frame-group. If this field is set to `0`, mobile pilot mode
is used. If the field is set to `1`, the fixed pilot mode is
used.
[0314] PAPR_FLAG: This 1-bit field indicates whether PAPR reduction
is used for the current frame in the current frame-group. If this
field is set to value `1`, tone reservation is used for PAPR
reduction. If this field is set to `0`, PAPR reduction is not
used.
[0315] FRU_CONFIGURE: This 3-bit field indicates the PHY profile
type configurations of the frame repetition units (FRU) that are
present in the current super-frame. All profile types conveyed in
the current super-frame are identified in this field in all
preambles in the current super-frame. The 3-bit field has a
different definition for each profile, as show in below table
8.
TABLE-US-00008 TABLE 8 Current Current Current Current PHY_PROFILE
= PHY_PROFILE = PHY_PROFILE = PHY_PROFILE = `000` `001` `010` `111`
(base) (handheld) (advanced) (FEF) FRU_CONFIGURE = 000 Only base
profile Only handheld Only advanced Only FEF present profile
present profile present present FRU_CONFIGURE = 1XX Handheld
profile Base profile Base profile Base profile present present
present present FRU_CONFIGURE = X1X Advanced profile Advanced
Handheld profile Handheld profile present profile present present
present FRU_CONFIGURE = XX1 FEF FEF FEF Advanced profile present
present present present
[0316] RESERVED: This 7-bit field is reserved for future use.
[0317] FIG. 13 illustrates PLS1 data according to an embodiment of
the present invention.
[0318] PLS1 data provides basic transmission parameters including
parameters required to enable the reception and decoding of the
PLS2. As above mentioned, the PLS1 data remain unchanged for the
entire duration of one frame-group. The detailed definition of the
signaling fields of the PLS1 data are as follows:
[0319] PREAMBLE_DATA: This 20-bit field is a copy of the preamble
signaling data excluding the EAC_FLAG.
[0320] NUM_FRAME_FRU: This 2-bit field indicates the number of the
frames per FRU.
[0321] PAYLOAD_TYPE: This 3-bit field indicates the format of the
payload data carried in the frame-group. PAYLOAD_TYPE is signaled
as shown in table 9.
TABLE-US-00009 TABLE 9 value Payload type 1XX TS stream is
transmitted X1X IP stream is transmitted XX1 GS stream is
transmitted
[0322] NUM_FSS: This 2-bit field indicates the number of FSS
symbols in the current frame.
[0323] SYSTEM_VERSION: This 8-bit field indicates the version of
the transmitted signal format. The SYSTEM_VERSION is divided into
two 4-bit fields, which are a major version and a minor
version.
[0324] Major version: The MSB four bits of SYSTEM_VERSION field
indicate major version information. A change in the major version
field indicates a non-backward-compatible change. The default value
is `0000`. For the version described in this standard, the value is
set to `0000`.
[0325] Minor version: The LSB four bits of SYSTEM_VERSION field
indicate minor version information. A change in the minor version
field is backward-compatible.
[0326] CELL_ID: This is a 16-bit field which uniquely identifies a
geographic cell in an ATSC network. An ATSC cell coverage area may
consist of one or more frequencies, depending on the number of
frequencies used per Futurecast UTB system. If the value of the
CELL_ID is not known or unspecified, this field is set to `0`.
[0327] NETWORK_ID: This is a 16-bit field which uniquely identifies
the current ATSC network.
[0328] SYSTEM_ID: This 16-bit field uniquely identifies the
Futurecast UTB system within the ATSC network. The Futurecast UTB
system is the terrestrial broadcast system whose input is one or
more input streams (TS, IP, GS) and whose output is an RF signal.
The Futurecast UTB system carries one or more PHY profiles and FEF,
if any. The same Futurecast UTB system may carry different input
streams and use different RF frequencies in different geographical
areas, allowing local service insertion. The frame structure and
scheduling is controlled in one place and is identical for all
transmissions within a Futurecast UTB system. One or more
Futurecast UTB systems may have the same SYSTEM_ID meaning that
they all have the same physical layer structure and
configuration.
[0329] The following loop consists of FRU_PHY_PROFILE,
FRU_FRAME_LENGTH, FRU_GI_FRACTION, and RESERVED which are used to
indicate the FRU configuration and the length of each frame type.
The loop size is fixed so that four PHY profiles (including a FEF)
are signaled within the FRU. If NUM_FRAME_FRU is less than 4, the
unused fields are filled with zeros.
[0330] FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile
type of the (i+1)th (i is the loop index) frame of the associated
FRU. This field uses the same signaling format as shown in the
table 8.
[0331] FRU_FRAME_LENGTH: This 2-bit field indicates the length of
the (i+1)th frame of the associated FRU. Using FRU_FRAME_LENGTH
together with FRU_GI_FRACTION, the exact value of the frame
duration can be obtained.
[0332] FRU_GI_FRACTION: This 3-bit field indicates the guard
interval fraction value of the (i+1)th frame of the associated FRU.
FRU_GI_FRACTION is signaled according to the table 7.
[0333] RESERVED: This 4-bit field is reserved for future use.
[0334] The following fields provide parameters for decoding the
PLS2 data.
[0335] PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used
by the PLS2 protection. The FEC type is signaled according to table
10. The details of the LDPC codes will be described later.
TABLE-US-00010 TABLE 10 Content PLS2 FEC type 00 4K-1/4 and 7K-3/10
LDPC codes 01~11 Reserved
[0336] PLS2_MOD: This 3-bit field indicates the modulation type
used by the PLS2. The modulation type is signaled according to
table 11.
TABLE-US-00011 TABLE 11 Value PLS2_MODE 000 BPSK 001 QPSK 010
QAM-16 011 NUQ-64 100~111 Reserved
[0337] PLS2_SIZE_CELL: This 15-bit field indicates Ctotalpartial
block, the size (specified as the number of QAM cells) of the
collection of full coded blocks for PLS2 that is carried in the
current frame-group. This value is constant during the entire
duration of the current frame-group.
[0338] PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in
bits, of the PLS2-STAT for the current frame-group. This value is
constant during the entire duration of the current frame-group.
[0339] PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in
bits, of the PLS2-DYN for the current frame-group. This value is
constant during the entire duration of the current frame-group.
[0340] PLS2_REP_FLAG: This 1-bit flag indicates whether the PLS2
repetition mode is used in the current frame-group. When this field
is set to value `1`, the PLS2 repetition mode is activated. When
this field is set to value `0`, the PLS2 repetition mode is
deactivated.
[0341] PLS2_REP_SIZE_CELL: This 15-bit field indicates
Ctotal_partial block, the size (specified as the number of QAM
cells) of the collection of partial coded blocks for PLS2 carried
in every frame of the current frame-group, when PLS2 repetition is
used. If repetition is not used, the value of this field is equal
to 0. This value is constant during the entire duration of the
current frame-group.
[0342] PLS2_NEXT_FEC_TYPE: This 2-bit field indicates the FEC type
used for PLS2 that is carried in every frame of the next
frame-group. The FEC type is signaled according to the table
10.
[0343] PLS2_NEXT_MOD: This 3-bit field indicates the modulation
type used for PLS2 that is carried in every frame of the next
frame-group. The modulation type is signaled according to the table
11.
[0344] PLS2_NEXT_REP_FLAG: This 1-bit flag indicates whether the
PLS2 repetition mode is used in the next frame-group. When this
field is set to value `1`, the PLS2 repetition mode is activated.
When this field is set to value `0`, the PLS2 repetition mode is
deactivated.
[0345] PLS2_NEXT_REP_SIZE_CELL: This 15-bit field indicates
Ctotal_full_block, The size (specified as the number of QAM cells)
of the collection of full coded blocks for PLS2 that is carried in
every frame of the next frame-group, when PLS2 repetition is used.
If repetition is not used in the next frame-group, the value of
this field is equal to 0. This value is constant during the entire
duration of the current frame-group.
[0346] PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the
size, in bits, of the PLS2-STAT for the next frame-group. This
value is constant in the current frame-group.
[0347] PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the
size, in bits, of the PLS2-DYN for the next frame-group. This value
is constant in the current frame-group.
[0348] PLS2_AP_MODE: This 2-bit field indicates whether additional
parity is provided for PLS2 in the current frame-group. This value
is constant during the entire duration of the current frame-group.
The below table 12 gives the values of this field. When this field
is set to `00`, additional parity is not used for the PLS2 in the
current frame-group.
TABLE-US-00012 TABLE 12 Value PLS2-AP mode 00 AP is not provided 01
AP1 mode 10~11 Reserved
[0349] PLS2_AP_SIZE_CELL: This 15-bit field indicates the size
(specified as the number of QAM cells) of the additional parity
bits of the PLS2. This value is constant during the entire duration
of the current frame-group.
[0350] PLS2_NEXT_AP_MODE: This 2-bit field indicates whether
additional parity is provided for PLS2 signaling in every frame of
next frame-group. This value is constant during the entire duration
of the current frame-group. The table 12 defines the values of this
field
[0351] PLS2_NEXT_AP_SIZE_CELL: This 15-bit field indicates the size
(specified as the number of QAM cells) of the additional parity
bits of the PLS2 in every frame of the next frame-group. This value
is constant during the entire duration of the current
frame-group.
[0352] RESERVED: This 32-bit field is reserved for future use.
[0353] CRC_32: A 32-bit error detection code, which is applied to
the entire PLS1 signaling.
[0354] FIG. 14 illustrates PLS2 data according to an embodiment of
the present invention.
[0355] FIG. 14 illustrates PLS2-STAT data of the PLS2 data. The
PLS2-STAT data are the same within a frame-group, while the
PLS2-DYN data provide information that is specific for the current
frame.
[0356] The details of fields of the PLS2-STAT data are as
follows:
[0357] FIC_FLAG: This 1-bit field indicates whether the FIC is used
in the current frame-group. If this field is set to `1`, the FIC is
provided in the current frame. If this field set to `0`, the FIC is
not carried in the current frame. This value is constant during the
entire duration of the current frame-group.
[0358] AUX_FLAG: This 1-bit field indicates whether the auxiliary
stream(s) is used in the current frame-group. If this field is set
to `1`, the auxiliary stream is provided in the current frame. If
this field set to `0`, the auxiliary stream is not carried in the
current frame. This value is constant during the entire duration of
current frame-group.
[0359] NUM_DP: This 6-bit field indicates the number of DPs carried
within the current frame. The value of this field ranges from 1 to
64, and the number of DPs is NUM_DP+1.
[0360] DP_ID: This 6-bit field identifies uniquely a DP within a
PHY profile.
[0361] DP_TYPE: This 3-bit field indicates the type of the DP. This
is signaled according to the below table 13.
TABLE-US-00013 TABLE 13 Value DP Type 000 DP Type 1 001 DP Type 2
010~111 reserved
[0362] DP_GROUP_ID: This 8-bit field identifies the DP group with
which the current DP is associated. This can be used by a receiver
to access the DPs of the service components associated with a
particular service, which will have the same DP_GROUP_ID.
[0363] BASE_DP_ID: This 6-bit field indicates the DP carrying
service signaling data (such as PSI/SI) used in the Management
layer. The DP indicated by BASE_DP_ID may be either a normal DP
carrying the service signaling data along with the service data or
a dedicated DP carrying only the service signaling data
[0364] DP_FEC_TYPE: This 2-bit field indicates the FEC type used by
the associated DP. The FEC type is signaled according to the below
table 14.
TABLE-US-00014 TABLE 14 Value FEC_TYPE 00 16K LDPC 01 64K LDPC
10~11 Reserved
[0365] DP_COD: This 4-bit field indicates the code rate used by the
associated DP. The code rate is signaled according to the below
table 15.
TABLE-US-00015 TABLE 15 Value Code rate 0000 5/15 0001 6/15 0010
7/15 0011 8/15 0100 9/15 0101 10/15 0110 11/15 0111 12/15 1000
13/15 1001~1111 Reserved
[0366] DP_MOD: This 4-bit field indicates the modulation used by
the associated DP. The modulation is signaled according to the
below table 16.
TABLE-US-00016 TABLE 16 Value Modulation 0000 QPSK 0001 QAM-16 0010
NUQ-64 0011 NUQ-256 0100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111
NUC-256 1000 NUC-1024 1001~1111 reserved
[0367] DP_SSD_FLAG: This 1-bit field indicates whether the SSD mode
is used in the associated DP. If this field is set to value `1`,
SSD is used. If this field is set to value `0`, SSD is not
used.
[0368] The following field appears only if PHY PROFILE is equal to
`010`, which indicates the advanced profile:
[0369] DP_MIMO: This 3-bit field indicates which type of MIMO
encoding process is applied to the associated DP. The type of MIMO
encoding process is signaled according to the table 17.
TABLE-US-00017 TABLE 17 Value MIMO encoding 000 FR-SM 001 FRFD-SM
010~111 reserved
[0370] DP_TI_TYPE: This 1-bit field indicates the type of
time-interleaving. A value of `0` indicates that one TI group
corresponds to one frame and contains one or more TI-blocks. A
value of `1` indicates that one TI group is carried in more than
one frame and contains only one TI-block.
[0371] DP_TI_LENGTH: The use of this 2-bit field (the allowed
values are only 1, 2, 4, 8) is determined by the values set within
the DP_TI_TYPE field as follows:
[0372] If the DP_TI_TYPE is set to the value `1`, this field
indicates PI, the number of the frames to which each TI group is
mapped, and there is one TI-block per TI group (NTI=1). The allowed
PI values with 2-bit field are defined in the below table 18.
[0373] If the DP_TI_TYPE is set to the value `0`, this field
indicates the number of TI-blocks NTI per TI group, and there is
one TI group per frame (PI=1). The allowed PI values with 2-bit
field are defined in the below table 18.
TABLE-US-00018 TABLE 18 2-bit field P.sub.I N.sub.TI 00 1 1 01 2 2
10 4 3 11 8 4
[0374] DP_FRAME_INTERVAL: This 2-bit field indicates the frame
interval (HUMP) within the frame-group for the associated DP and
the allowed values are 1, 2, 4, 8 (the corresponding 2-bit field is
`00`, `01`, `10`, or `11`, respectively). For DPs that do not
appear every frame of the frame-group, the value of this field is
equal to the interval between successive frames. For example, if a
DP appears on the frames 1, 5, 9, 13, etc., this field is set to
`4`. For DPs that appear in every frame, this field is set to
`1`.
[0375] DP_TI_BYPASS: This 1-bit field determines the availability
of time interleaver. If time interleaving is not used for a DP, it
is set to `1`. Whereas if time interleaving is used it is set to
`0`.
[0376] DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of
the first frame of the super-frame in which the current DP occurs.
The value of DP_FIRST_FRAME_IDX ranges from 0 to 31
[0377] DP_NUM_BLOCK_MAX: This 10-bit field indicates the maximum
value of DP_NUM_BLOCKS for this DP. The value of this field has the
same range as DP_NUM_BLOCKS.
[0378] DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the
payload data carried by the given DP. DP_PAYLOAD_TYPE is signaled
according to the below table 19.
TABLE-US-00019 TABLE 19 Value Payload Type 00 TS. 01 IP 10 GS 11
reserved
[0379] DP_INBAND_MODE: This 2-bit field indicates whether the
current DP carries in-band signaling information. The in-band
signaling type is signaled according to the below table 20.
TABLE-US-00020 TABLE 20 Value In-band mode 00 In-band signaling is
not carried. 01 INBAND-PLS is carried only 10 INBAND-ISSY is
carried only 11 INBAND-PLS and INBAND-ISSY are carried
[0380] DP_PROTOCOL_TYPE: This 2-bit field indicates the protocol
type of the payload carried by the given DP. It is signaled
according to the below table 21 when input payload types are
selected.
TABLE-US-00021 TABLE 21 If DP_PAYLOAD_TYPE If DP_PAYLOAD_TYPE If
DP_PAYLOAD_TYPE Value Is TS Is IP Is GS 00 MPEG2-TS IPv4 (Note) 01
Reserved IPv6 Reserved 10 Reserved Reserved Reserved 11 Reserved
Reserved Reserved
[0381] DP_CRC_MODE: This 2-bit field indicates whether CRC encoding
is used in the Input Formatting block. The CRC mode is signaled
according to the below table 22.
TABLE-US-00022 TABLE 22 Value CRC mode 00 Not used 01 CRC-8 10
CRC-16 11 CRC-32
[0382] DNP_MODE: This 2-bit field indicates the null-packet
deletion mode used by the associated DP when DP_PAYLOAD_TYPE is set
to TS (`00`). DNP_MODE is signaled according to the below table 23.
If DP_PAYLOAD_TYPE is not TS (`00`), DNP_MODE is set to the value
`00`.
TABLE-US-00023 TABLE 23 Value Null-packet deletion mode 00 Not used
01 DNP-NORMAL 10 DNP-OFFSET 11 reserved
[0383] ISSY_MODE: This 2-bit field indicates the ISSY mode used by
the associated DP when DP_PAYLOAD_TYPE is set to TS (`00`). The
ISSY_MODE is signaled according to the below table 24 If
DP_PAYLOAD_TYPE is not TS (`00`), ISSY_MODE is set to the value
`00`.
TABLE-US-00024 TABLE 24 Value ISSY mode 00 Not used 01 ISSY-UP 10
ISSY-BBF 11 reserved
[0384] HC_MODE_TS: This 2-bit field indicates the TS header
compression mode used by the associated DP when DP_PAYLOAD_TYPE is
set to TS (`00`). The HC_MODE_TS is signaled according to the below
table 25.
TABLE-US-00025 TABLE 25 Value Header compression mode 00 HC_MODE_TS
1 01 HC_MODE_TS 2 10 HC_MODE_TS 3 11 HC_MODE_TS 4
[0385] HC_MODE_IP: This 2-bit field indicates the IP header
compression mode when DP_PAYLOAD_TYPE is set to IP (`01`). The
HC_MODE_IP is signaled according to the below table 26.
TABLE-US-00026 TABLE 26 Value Header compression mode 00 No
compression 01 HC_MODE_IP 1 10~11 reserved
[0386] PID: This 13-bit field indicates the PID number for TS
header compression when DP_PAYLOAD_TYPE is set to TS (`00`) and
HC_MODE_TS is set to `01` or `10`.
[0387] RESERVED: This 8-bit field is reserved for future use.
[0388] The following field appears only if FIC_FLAG is equal to
`1`:
[0389] FIC_VERSION: This 8-bit field indicates the version number
of the FIC.
[0390] FIC_LENGTH_BYTE: This 13-bit field indicates the length, in
bytes, of the FIC.
[0391] RESERVED: This 8-bit field is reserved for future use.
[0392] The following field appears only if AUX_FLAG is equal to
`1`:
[0393] NUM_AUX: This 4-bit field indicates the number of auxiliary
streams. Zero means no auxiliary streams are used.
[0394] AUX_CONFIG_RFU: This 8-bit field is reserved for future
use.
[0395] AUX_STREAM_TYPE: This 4-bit is reserved for future use for
indicating the type of the current auxiliary stream.
[0396] AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future
use for signaling auxiliary streams.
[0397] FIG. 15 illustrates PLS2 data according to another
embodiment of the present invention.
[0398] FIG. 15 illustrates PLS2-DYN data of the PLS2 data. The
values of the PLS2-DYN data may change during the duration of one
frame-group, while the size of fields remains constant.
[0399] The details of fields of the PLS2-DYN data are as
follows:
[0400] FRAME_INDEX: This 5-bit field indicates the frame index of
the current frame within the super-frame. The index of the first
frame of the super-frame is set to `0`.
[0401] PLS_CHANGE_COUNTER: This 4-bit field indicates the number of
super-frames ahead where the configuration will change. The next
super-frame with changes in the configuration is indicated by the
value signaled within this field. If this field is set to the value
`0000`, it means that no scheduled change is foreseen: e.g., value
`1` indicates that there is a change in the next super-frame.
[0402] FIC_CHANGE_COUNTER: This 4-bit field indicates the number of
super-frames ahead where the configuration (i.e., the contents of
the FIC) will change. The next super-frame with changes in the
configuration is indicated by the value signaled within this field.
If this field is set to the value `0000`, it means that no
scheduled change is foreseen: e.g. value `0001` indicates that
there is a change in the next super-frame.
[0403] RESERVED: This 16-bit field is reserved for future use.
[0404] The following fields appear in the loop over NUM_DP, which
describe the parameters associated with the DP carried in the
current frame.
[0405] DP_ID: This 6-bit field indicates uniquely the DP within a
PHY profile.
[0406] DP_START: This 15-bit (or 13-bit) field indicates the start
position of the first of the DPs using the DPU addressing scheme.
The DP_START field has differing length according to the PHY
profile and FFT size as shown in the below table 27.
TABLE-US-00027 TABLE 27 DP_START field size PHY profile 64K 16K
Base 13 bit 15 bit Handheld -- 13 bit Advanced 13 bit 15 bit
[0407] DP_NUM_BLOCK: This 10-bit field indicates the number of FEC
blocks in the current TI group for the current DP. The value of
DP_NUM_BLOCK ranges from 0 to 1023
[0408] RESERVED: This 8-bit field is reserved for future use.
[0409] The following fields indicate the FIC parameters associated
with the EAC.
[0410] EAC_FLAG: This 1-bit field indicates the existence of the
EAC in the current frame. This bit is the same value as the
EAC_FLAG in the preamble.
[0411] EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the
version number of a wake-up indication.
[0412] If the EAC_FLAG field is equal to `1`, the following 12 bits
are allocated for EAC_LENGTH_BYTE field. If the EAC_FLAG field is
equal to `0`, the following 12 bits are allocated for
EAC_COUNTER.
[0413] EAC_LENGTH_BYTE: This 12-bit field indicates the length, in
byte, of the EAC.
[0414] EAC_COUNTER: This 12-bit field indicates the number of the
frames before the frame where the EAC arrives.
[0415] The following field appears only if the AUX_FLAG field is
equal to `1`:
[0416] AUX_PRIVATE_DYN: This 48-bit field is reserved for future
use for signaling auxiliary streams. The meaning of this field
depends on the value of AUX_STREAM_TYPE in the configurable
PLS2-STAT.
[0417] CRC_32: A 32-bit error detection code, which is applied to
the entire PLS2.
[0418] FIG. 16 illustrates a logical structure of a frame according
to an embodiment of the present invention.
[0419] As above mentioned, the PLS, EAC, FIC, DPs, auxiliary
streams and dummy cells are mapped into the active carriers of the
OFDM symbols in the frame. The PLS 1 and PLS2 are first mapped into
one or more FSS(s). After that, EAC cells, if any, are mapped
immediately following the PLS field, followed next by FIC cells, if
any. The DPs are mapped next after the PLS or EAC, FIC, if any.
Type 1 DPs follows first, and Type 2 DPs next. The details of a
type of the DP will be described later. In some case, DPs may carry
some special data for EAS or service signaling data. The auxiliary
stream or streams, if any, follow the DPs, which in turn are
followed by dummy cells. Mapping them all together in the above
mentioned order, i.e. PLS, EAC, FIC, DPs, auxiliary streams and
dummy data cells exactly fill the cell capacity in the frame.
[0420] FIG. 17 illustrates PLS mapping according to an embodiment
of the present invention.
[0421] PLS cells are mapped to the active carriers of FSS(s).
Depending on the number of cells occupied by PLS, one or more
symbols are designated as FSS(s), and the number of FSS(s) NFSS is
signaled by NUM_FSS in PLS1. The FSS is a special symbol for
carrying PLS cells. Since robustness and latency are critical
issues in the PLS, the FSS(s) has higher density of pilots allowing
fast synchronization and frequency-only interpolation within the
FSS.
[0422] PLS cells are mapped to active carriers of the NFSS FSS(s)
in a top-down manner as shown in an example in FIG. 17. The PLS1
cells are mapped first from the first cell of the first FSS in an
increasing order of the cell index. The PLS2 cells follow
immediately after the last cell of the PLS1 and mapping continues
downward until the last cell index of the first FSS. If the total
number of required PLS cells exceeds the number of active carriers
of one FSS, mapping proceeds to the next FSS and continues in
exactly the same manner as the first FSS.
[0423] After PLS mapping is completed, DPs are carried next. If
EAC, FIC or both are present in the current frame, they are placed
between PLS and "normal" DPs.
[0424] FIG. 18 illustrates EAC mapping according to an embodiment
of the present invention.
[0425] EAC is a dedicated channel for carrying EAS messages and
links to the DPs for EAS. EAS support is provided but EAC itself
may or may not be present in every frame. EAC, if any, is mapped
immediately after the PLS2 cells. EAC is not preceded by any of the
FIC, DPs, auxiliary streams or dummy cells other than the PLS
cells. The procedure of mapping the EAC cells is exactly the same
as that of the PLS.
[0426] The EAC cells are mapped from the next cell of the PLS2 in
increasing order of the cell index as shown in the example in FIG.
18. Depending on the EAS message size, EAC cells may occupy a few
symbols, as shown in FIG. 18.
[0427] EAC cells follow immediately after the last cell of the
PLS2, and mapping continues downward until the last cell index of
the last FSS. If the total number of required EAC cells exceeds the
number of remaining active carriers of the last FSS mapping
proceeds to the next symbol and continues in exactly the same
manner as FSS(s). The next symbol for mapping in this case is the
normal data symbol, which has more active carriers than a FSS.
[0428] After EAC mapping is completed, the FIC is carried next, if
any exists. If FIC is not transmitted (as signaled in the PLS2
field), DPs follow immediately after the last cell of the EAC.
[0429] FIG. 19 illustrates FIC mapping according to an embodiment
of the present invention.
[0430] (a) shows an example mapping of FIC cell without EAC and (b)
shows an example mapping of FIC cell with EAC.
[0431] FIC is a dedicated channel for carrying cross-layer
information to enable fast service acquisition and channel
scanning. This information primarily includes channel binding
information between DPs and the services of each broadcaster. For
fast scan, a receiver can decode FIC and obtain information such as
broadcaster ID, number of services, and BASE_DP_ID. For fast
service acquisition, in addition to FIC, base DP can be decoded
using BASE_DP_ID. Other than the content it carries, a base DP is
encoded and mapped to a frame in exactly the same way as a normal
DP. Therefore, no additional description is required for a base DP.
The FIC data is generated and consumed in the Management Layer. The
content of FIC data is as described in the Management Layer
specification.
[0432] The FIC data is optional and the use of FIC is signaled by
the FIC_FLAG parameter in the static part of the PLS2. If FIC is
used, FIC_FLAG is set to `1` and the signaling field for FIC is
defined in the static part of PLS2. Signaled in this field are
FIC_VERSION, and FIC_LENGTH_BYTE. FIC uses the same modulation,
coding and time interleaving parameters as PLS2. FIC shares the
same signaling parameters such as PLS2_MOD and PLS2_FEC. FIC data,
if any, is mapped immediately after PLS2 or EAC if any. FIC is not
preceded by any normal DPs, auxiliary streams or dummy cells. The
method of mapping FIC cells is exactly the same as that of EAC
which is again the same as PLS.
[0433] Without EAC after PLS, FIC cells are mapped from the next
cell of the PLS2 in an increasing order of the cell index as shown
in an example in (a). Depending on the FIC data size, FIC cells may
be mapped over a few symbols, as shown in (b).
[0434] FIC cells follow immediately after the last cell of the
PLS2, and mapping continues downward until the last cell index of
the last FSS. If the total number of required FIC cells exceeds the
number of remaining active carriers of the last FSS, mapping
proceeds to the next symbol and continues in exactly the same
manner as FSS(s). The next symbol for mapping in this case is the
normal data symbol which has more active carriers than a FSS.
[0435] If EAS messages are transmitted in the current frame, EAC
precedes FIC, and FIC cells are mapped from the next cell of the
EAC in an increasing order of the cell index as shown in (b).
[0436] After FIC mapping is completed, one or more DPs are mapped,
followed by auxiliary streams, if any, and dummy cells.
[0437] FIG. 20 illustrates a type of DP according to an embodiment
of the present invention.
[0438] (a) shows type 1 DP and (b) shows type 2 DP.
[0439] After the preceding channels, i.e., PLS, EAC and FIC, are
mapped, cells of the DPs are mapped. A DP is categorized into one
of two types according to mapping method:
[0440] Type 1 DP: DP is mapped by TDM
[0441] Type 2 DP: DP is mapped by FDM
[0442] The type of DP is indicated by DP_TYPE field in the static
part of PLS2. FIG. 20 illustrates the mapping orders of Type 1 DPs
and Type 2 DPs. Type 1 DPs are first mapped in the increasing order
of cell index, and then after reaching the last cell index, the
symbol index is increased by one. Within the next symbol, the DP
continues to be mapped in the increasing order of cell index
starting from p=0. With a number of DPs mapped together in one
frame, each of the Type 1 DPs are grouped in time, similar to TDM
multiplexing of DPs.
[0443] Type 2 DPs are first mapped in the increasing order of
symbol index, and then after reaching the last OFDM symbol of the
frame, the cell index increases by one and the symbol index rolls
back to the first available symbol and then increases from that
symbol index. After mapping a number of DPs together in one frame,
each of the Type 2 DPs are grouped in frequency together, similar
to FDM multiplexing of DPs.
[0444] Type 1 DPs and Type 2 DPs can coexist in a frame if needed
with one restriction; Type 1 DPs always precede Type 2 DPs. The
total number of OFDM cells carrying Type 1 and Type 2 DPs cannot
exceed the total number of OFDM cells available for transmission of
DPs:
D.sub.DP1+,D.sub.DP2.ltoreq.D.sub.DP [Math FIG. 2]
[0445] where DDP1 is the number of OFDM cells occupied by Type 1
DPs, DDP2 is the number of cells occupied by Type 2 DPs. Since PLS,
EAC, FIC are all mapped in the same way as Type 1 DP, they all
follow "Type 1 mapping rule". Hence, overall, Type 1 mapping always
precedes Type 2 mapping.
[0446] FIG. 21 illustrates DP mapping according to an embodiment of
the present invention.
[0447] (a) shows an addressing of OFDM cells for mapping type 1 DPs
and (b) shows an addressing of OFDM cells for mapping for type 2
DPs.
[0448] Addressing of OFDM cells for mapping Type 1 DPs (0, . . . ,
DDP1-1) is defined for the active data cells of Type 1 DPs. The
addressing scheme defines the order in which the cells from the TIs
for each of the Type 1 DPs are allocated to the active data cells.
It is also used to signal the locations of the DPs in the dynamic
part of the PLS2.
[0449] Without EAC and FIC, address 0 refers to the cell
immediately following the last cell carrying PLS in the last FSS.
If EAC is transmitted and FIC is not in the corresponding frame,
address 0 refers to the cell immediately following the last cell
carrying EAC. If FIC is transmitted in the corresponding frame,
address 0 refers to the cell immediately following the last cell
carrying FIC. Address 0 for Type 1 DPs can be calculated
considering two different cases as shown in (a). In the example in
(a), PLS, EAC and FIC are assumed to be all transmitted. Extension
to the cases where either or both of EAC and FIC are omitted is
straightforward. If there are remaining cells in the FSS after
mapping all the cells up to FIC as shown on the left side of
(a).
[0450] Addressing of OFDM cells for mapping Type 2 DPs (0, . . . ,
DDP2-1) is defined for the active data cells of Type 2 DPs. The
addressing scheme defines the order in which the cells from the TIs
for each of the Type 2 DPs are allocated to the active data cells.
It is also used to signal the locations of the DPs in the dynamic
part of the PLS2.
[0451] Three slightly different cases are possible as shown in (b).
For the first case shown on the left side of (b), cells in the last
FSS are available for Type 2 DP mapping. For the second case shown
in the middle, FIC occupies cells of a normal symbol, but the
number of FIC cells on that symbol is not larger than CFSS. The
third case, shown on the right side in
[0452] (b), is the same as the second case except that the number
of FIC cells mapped on that symbol exceeds CFSS.
[0453] The extension to the case where Type 1 DP(s) precede Type 2
DP(s) is straightforward since PLS, EAC and FIC follow the same
"Type 1 mapping rule" as the Type 1 DP(s).
[0454] A data pipe unit (DPU) is a basic unit for allocating data
cells to a DP in a frame.
[0455] A DPU is defined as a signaling unit for locating DPs in a
frame. A Cell Mapper 7010 may map the cells produced by the TIs for
each of the DPs. A Time interleaver 5050 outputs a series of
TI-blocks and each TI-block comprises a variable number of
XFECBLOCKs which is in turn composed of a set of cells. The number
of cells in an XFECBLOCK, Ncells, is dependent on the FECBLOCK
size, Nldpc, and the number of transmitted bits per constellation
symbol. A DPU is defined as the greatest common divisor of all
possible values of the number of cells in a XFECBLOCK, Ncells,
supported in a given PHY profile. The length of a DPU in cells is
defined as LDPU. Since each PHY profile supports different
combinations of FECBLOCK size and a different number of bits per
constellation symbol, LDPU is defined on a PHY profile basis.
[0456] FIG. 22 illustrates an FEC structure according to an
embodiment of the present invention.
[0457] FIG. 22 illustrates an FEC structure according to an
embodiment of the present invention before bit interleaving. As
above mentioned, Data FEC encoder may perform the FEC encoding on
the input BBF to generate FECBLOCK procedure using outer coding
(BCH), and inner coding (LDPC). The illustrated FEC structure
corresponds to the FECBLOCK. Also, the FECBLOCK and the FEC
structure have same value corresponding to a length of LDPC
codeword.
[0458] The BCH encoding is applied to each BBF (Kbch bits), and
then LDPC encoding is applied to BCH-encoded BBF (Kldpc bits=Nbch
bits) as illustrated in FIG. 22.
[0459] The value of Nldpc is either 64800 bits (long FECBLOCK) or
16200 bits (short FECBLOCK).
[0460] The below table 28 and table 29 show FEC encoding parameters
for a long FECBLOCK and a short FECBLOCK, respectively.
TABLE-US-00028 TABLE 28 BCH error LDPC correction Rate N.sub.ldpc
K.sub.ldpc K.sub.bch capability N.sub.bch - K.sub.bch 5/15 64800
21600 21408 12 192 6/15 25920 25728 7/15 30240 30048 8/15 34560
34368 9/15 38880 38688 10/15 43200 43008 11/15 47520 47328 12/15
51840 51648 13/15 56160 55968
TABLE-US-00029 TABLE 29 BCH error LDPC correction Rate N.sub.ldpc
K.sub.ldpc K.sub.bch capability N.sub.bch - K.sub.bch 5/15 16200
5400 5232 12 168 6/15 6480 6312 7/15 7560 7392 8/15 8640 8472 9/15
9720 9552 10/15 10800 10632 11/15 11880 11712 12/15 12960 12792
13/15 14040 13872
[0461] The details of operations of the BCH encoding and LDPC
encoding are as follows:
[0462] A 12-error correcting BCH code is used for outer encoding of
the BBF. The BCH generator polynomial for short FECBLOCK and long
FECBLOCK are obtained by multiplying together all polynomials.
[0463] LDPC code is used to encode the output of the outer BCH
encoding. To generate a completed Bldpc (FECBLOCK), Pldpc (parity
bits) is encoded systematically from each Ildpc (BCH-encoded BBF),
and appended to Ildpc. The completed Bldpc (FECBLOCK) are expressed
as follow Math figure.
B.sub.ldpc-[I.sup.ldpcP.sup.ldpc]=[i.sub.0i.sub.1, . . .
i.sub.K.sub.ldpc.sub.-1,p.sub.0,p.sub.1, . . .
,p.sub.N.sub.ldpc.sub.-K.sub.ldpc.sub.-1] [Math FIG. 3]
[0464] The parameters for long FECBLOCK and short FECBLOCK are
given in the above table 28 and 29, respectively.
[0465] The detailed procedure to calculate Nldpc-Kldpc parity bits
for long FECBLOCK, is as follows:
[0466] 1) Initialize the parity bits,
B.sub.ldpc=[I.sub.ldpcP.sub.ldpc]=[i.sub.0,i.sub.1, . . .
,i.sub.K.sub.ldpc.sub.-1,p.sub.0,p.sub.1. . .
,p.sub.N.sub.ldpc.sub.-K.sub.ldpc.sub.-1] [Math FIG. 4]
[0467] 2) Accumulate the first information bit--i0, at parity bit
addresses specified in the first row of addresses of parity check
matrix. The details of addresses of parity check matrix will be
described later. For example, for rate 13/15:
p 983 = p 983 .sym. i 0 p 2815 = p 2815 .sym. i 0 p 4837 = p 4837
.sym. i 0 p 4989 = p 4989 .sym. i 0 p 6138 = p 6138 .sym. i 0 p
6458 = p 6458 .sym. i 0 p 6921 = p 6921 .sym. i 0 p 6974 = p 6974
.sym. i 0 p 7572 = p 7572 .sym. i 0 p 8260 = p 8260 .sym. i 0 p
8496 = p 8496 .sym. i 0 [ Math Figure 5 ] ##EQU00001##
[0468] 3) For the next 359 information bits, is, s=1, 2, . . . ,
359 accumulate is at parity bit addresses using following Math
figure.
{x+(s mod 360).times.Q.sub.ldpc} mod (N.sub.ldpc-K.sub.ldpc) [Math
FIG. 6]
[0469] where x denotes the address of the parity bit accumulator
corresponding to the first bit i0, and Qldpc is a code rate
dependent constant specified in the addresses of parity check
matrix. Continuing with the example, Qldpc=24 for rate 13/15, so
for information bit i1, the following operations are performed:
p 1007 = p 1007 .sym. i 1 p 2839 = p 2839 .sym. i 1 p 4861 = p 4861
.sym. i 1 p 5013 = p 5013 .sym. i 1 p 6162 = p 6162 .sym. i 1 p
6482 = p 6482 .sym. i 1 p 6945 = p 6945 .sym. i 1 p 6998 = p 6998
.sym. i 1 p 7596 = p 7596 .sym. i 1 p 8284 = p 8284 .sym. i 1 p
8520 = p 8520 .sym. i 1 [ Math Figure 7 ] ##EQU00002##
[0470] 4) For the 361st information bit i360, the addresses of the
parity bit accumulators are given in the second row of the
addresses of parity check matrix. In a similar manner the addresses
of the parity bit accumulators for the following 359 information
bits is, s=361, 362, . . . , 719 are obtained using the Math FIG.
6, where x denotes the address of the parity bit accumulator
corresponding to the information bit i360, i.e., the entries in the
second row of the addresses of parity check matrix.
[0471] 5) In a similar manner, for every group of 360 new
information bits, a new row from addresses of parity check matrixes
used to find the addresses of the parity bit accumulators.
[0472] After all of the information bits are exhausted, the final
parity bits are obtained as follows:
[0473] 6) Sequentially perform the following operations starting
with i=1
p.sub.i=p.sub.i.sym.p.sub.i-1,i=1,2, . . . ,N.sub.ldpc-K.sub.ldpc-1
[Math FIG. 8]
[0474] where final content of pi, i=0,1, . . . Nldpc-Kldpc-1 is
equal to the parity bit pi.
TABLE-US-00030 TABLE 30 Code Rate Q.sub.ldpc 5/15 120 6/15 108 7/15
96 8/15 84 9/15 72 10/15 60 11/15 48 12/15 36 13/15 24
[0475] This LDPC encoding procedure for a short FECBLOCK is in
accordance with t LDPC encoding procedure for the long FECBLOCK,
except replacing the table 30 with table 31, and replacing the
addresses of parity check matrix for the long FECBLOCK with the
addresses of parity check matrix for the short FECBLOCK.
TABLE-US-00031 TABLE 31 Code Rate Q.sub.ldpc 5/15 30 6/15 27 7/15
24 8/15 21 9/15 18 10/15 15 11/15 12 12/15 9 13/15 6
[0476] FIG. 23 illustrates a bit interleaving according to an
embodiment of the present invention.
[0477] The outputs of the LDPC encoder are bit-interleaved, which
consists of parity interleaving followed by Quasi-Cyclic Block
(QCB) interleaving and inner-group interleaving.
[0478] (a) shows Quasi-Cyclic Block (QCB) interleaving and (b)
shows inner-group interleaving.
[0479] The FECBLOCK may be parity interleaved. At the output of the
parity interleaving, the LDPC codeword consists of 180 adjacent QC
blocks in a long FECBLOCK and 45 adjacent QC blocks in a short
FECBLOCK. Each QC block in either a long or short FECBLOCK consists
of 360 bits. The parity interleaved LDPC codeword is interleaved by
QCB interleaving. The unit of QCB interleaving is a QC block. The
QC blocks at the output of parity interleaving are permutated by
QCB interleaving as illustrated in FIG. 23, where
Ncells=64800/.eta. mod or 16200/.eta. mod according to the FECBLOCK
length. The QCB interleaving pattern is unique to each combination
of modulation type and LDPC code rate.
[0480] After QCB interleaving, inner-group interleaving is
performed according to modulation type and order (.eta. mod) which
is defined in the below table 32. The number of QC blocks for one
inner-group, NQCB_IG, is also defined.
TABLE-US-00032 TABLE 32 Modulation type .eta..sub.mod
N.sub.QCB.sub.--.sub.IG QAM-16 4 2 NUC-16 4 4 NUQ-64 6 3 NUC-64 6 6
NUQ-256 8 4 NUC-256 8 8 NUQ-1024 10 5 NUC-1024 10 10
[0481] The inner-group interleaving process is performed with
NQCB_IG QC blocks of the QCB interleaving output. Inner-group
interleaving has a process of writing and reading the bits of the
inner-group using 360 columns and NQCB_IG rows. In the write
operation, the bits from the QCB interleaving output are written
row-wise. The read operation is performed column-wise to read out m
bits from each row, where m is equal to 1 for NUC and 2 for
NUQ.
[0482] FIG. 24 illustrates a cell-word demultiplexing according to
an embodiment of the present invention.
[0483] (a) shows a cell-word demultiplexing for 8 and 12 bpcu MIMO
and (b) shows a cell-word demultiplexing for 10 bpcu MIMO.
[0484] Each cell word (c0,1, c1,1, . . . , c.eta. mod-1,1) of the
bit interleaving output is demultiplexed into (d1,0,m, d1,1,m . . .
, d1,.eta. mod-1,m) and (d2,0,m, d2,1,m . . . , d2,.eta. mod-1,m)
as shown in (a), which describes the cell-word demultiplexing
process for one XFECBLOCK.
[0485] For the 10 bpcu MIMO case using different types of NUQ for
MIMO encoding, the Bit Interleaver for NUQ-1024 is re-used. Each
cell word (c0,1, c1,1, . . . , c9,1) of the Bit Interleaver output
is demultiplexed into (d1,0,m, d1,1,m . . . , d1,3,m) and (d2,0,m,
d2,1,m . . . , d2,5,m), as shown in (b).
[0486] FIG. 25 illustrates a time interleaving according to an
embodiment of the present invention.
[0487] (a) to (c) show examples of TI mode.
[0488] The time interleaver operates at the DP level. The
parameters of time interleaving (TI) may be set differently for
each DP.
[0489] The following parameters, which appear in part of the
PLS2-STAT data, configure the TI:
[0490] DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode;
`0` indicates the mode with multiple TI blocks (more than one TI
block) per TI group. In this case, one TI group is directly mapped
to one frame (no inter-frame interleaving). `1` indicates the mode
with only one TI block per TI group. In this case, the TI block may
be spread over more than one frame (inter-frame interleaving).
[0491] DP_TI_LENGTH: If DP_TI_TYPE=`0`, this parameter is the
number of TI blocks NTI per TI group. For DP_TI_TYPE=`1`, this
parameter is the number of frames PI spread from one TI group.
[0492] DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the
maximum number of XFECBLOCKs per TI group.
[0493] DP_FRAME_INTERVAL (allowed values: 1, 2, 4, 8): Represents
the number of the frames IJUMP between two successive frames
carrying the same DP of a given PHY profile.
[0494] DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving
is not used for a DP, this parameter is set to `1`. It is set to
`0` if time interleaving is used.
[0495] Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN
data is used to represent the number of XFECBLOCKs carried by one
TI group of the DP.
[0496] When time interleaving is not used for a DP, the following
TI group, time interleaving operation, and TI mode are not
considered. However, the Delay Compensation block for the dynamic
configuration information from the scheduler will still be
required. In each DP, the XFECBLOCKs received from the SSD/MIMO
encoding are grouped into TI groups. That is, each TI group is a
set of an integer number of XFECBLOCKs and will contain a
dynamically variable number of XFECBLOCKs. The number of XFECBLOCKs
in the TI group of index n is denoted by NxBLOCK_Group(n) and is
signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note that
NxBLOCK_Group(n) may vary from the minimum value of 0 to the
maximum value NxBLOCK_Group_MAX (corresponding to DP_NUM_BLOCK_MAX)
of which the largest value is 1023.
[0497] Each TI group is either mapped directly onto one frame or
spread over PI frames. Each TI group is also divided into more than
one TI blocks (NTI), where each TI block corresponds to one usage
of time interleaver memory. The TI blocks within the TI group may
contain slightly different numbers of XFECBLOCKs. If the TI group
is divided into multiple TI blocks, it is directly mapped to only
one frame. There are three options for time interleaving (except
the extra option of skipping the time interleaving) as shown in the
below table 33.
TABLE-US-00033 TABLE 33 Modes Descriptions Option-1 Each TI group
contains one TI block and is mapped directly to one frame as shown
in (a). This option is signaled in the PLS2-STAT by DP_TI_TYPE =
`0` and DP_TI_LENGTH = `1` (N.sub.TI = 1). Option-2 Each TI group
contains one TI block and is mapped to more than one frame. (b)
shows an example, where one TI group is mapped to two frames, i.e.,
DP_TI_LENGTH = `2` (P.sub.I = 2) and DP_FRAME_INTERVAL (I.sub.JUMP
= 2). This provides greater time diversity for low data-rate
services. This option is signaled in the PLS2-STAT by DP_TI_TYPE =
`1`. Option-3 Each TI group is divided into multiple TI blocks and
is mapped directly to one frame as shown in (c). Each TI block may
use full TI memory, so as to provide the maximum bit-rate for a DP.
This option is signaled in the PLS2-STAT signaling by DP_TI_TYPE =
`0` and DP_TI_LENGTH = N.sub.TI, while P.sub.I = 1.
[0498] In each DP, the TI memory stores the input XFECBLOCKs
(output XFECBLOCKs from the SSD/MIMO encoding block). Assume that
input XFECBLOCKs are defined as
( d n , s , 0 , 0 , d n , s , 0 , 1 , , d n , s , 0 , N cells - 1 ,
d n , s , 1 , 0 , , d n , s , 1 , N cells - 1 , , d n , s , N
xBLOCK _ TI ( n , s ) - 1 , 0 , , d n , s , N xBLOCK _ TI ( n , s )
- 1 , N cells - 1 ) , ##EQU00003##
[0499] where d.sub.n,s,r,q is the qth cell of the rth XFECBLOCK in
the sth TI block of the nth TI group and represents the outputs of
SSD and MIMO encodings as follows.
d n , s , r , q = { f n , s , r , q , the output of SSD encoding g
n , s , r , q , the output of MIMO encoding . ##EQU00004##
[0500] In addition, assume that output XFECBLOCKs from the time
interleaver are defined as
( h n , s , 0 , h n , s , 1 , , h n , s , i , , h n , s , N xBLOCK
_ TI ( n , s ) .times. N cells - 1 ) , ##EQU00005##
[0501] where h.sub.n,s,i is the ith output cell (for i=0, . . . ,
N.sub.xBLOCK_TI (n,s).times.N.sub.cells-1) in the sth TI block of
the nth TI group.
[0502] Typically, the time interleaver will also act as a buffer
for DP data prior to the process of frame building. This is
achieved by means of two memory banks for each DP. The first
TI-block is written to the first bank. The second TI-block is
written to the second bank while the first bank is being read from
and so on.
[0503] The TI is a twisted row-column block interleaver. For the
sth TI block of the nth TI group, the number of rows N.sub.r of a
TI memory is equal to the number of cells i.e., N.sub.cells, i.e.,
N.sub.r=N.sub.cells while the number of columns N.sub.c is equal to
the number N.sub.xBLOCK_TI (n,s).
[0504] FIG. 26 illustrates the basic operation of a twisted
row-column block interleaver according to an embodiment of the
present invention.
[0505] shows a writing operation in the time interleaver and (b)
shows a reading operation in the time interleaver The first
XFECBLOCK is written column-wise into the first column of the TI
memory, and the second XFECBLOCK is written into the next column,
and so on as shown in (a). Then, in the interleaving array, cells
are read out diagonal-wise. During diagonal-wise reading from the
first row (rightwards along the row beginning with the left-most
column) to the last row, N.sub.r cells are read out as shown in
(b). In detail, assuming z.sub.n,s,i=0, . . . , N.sub.rN.sub.c) as
the TI memory cell position to be read sequentially, the reading
process in such an interleaving array is performed by calculating
the row index R.sub.n,s,i, the column index C.sub.n,s,i, and the
associated twisting parameter T.sub.n,s,i as follows
expression.
GENERATE ( R n , s , i , C n , s , i ) = { R n , s , i = mod ( i ,
N r ) , T n , s , i = mod ( S shift .times. R n , s , i , N c ) , C
n , s , i = mod ( T n , s , i + i N r , N c ) } [ Math Figure 9 ]
##EQU00006##
[0506] where S.sub.shift is a common shift value for the
diagonal-wise reading process regardless of N.sub.xBLOCK_TI (n,s),
and it is determined by N.sub.xBLOCK_TI_MAX given in the PLS2-STAT
as follows expression.
for { N xBLOCK _ TI _ MAX ' = N xBLOCK _ TI _ MAX + 1 , if N xBLOCK
_ TI _ MAX mod 2 = 0 N xBLOCK _ TI _ MAX ' = N xBLOCK _ TI _ MAX ,
if N xBLOCK _ TI _ MAX mod 2 = 1 , S shift = N xBLOCK _ TI _ MAX '
- 1 2 [ Math Figure 10 ] ##EQU00007##
[0507] As a result, the cell positions to be read are calculated by
a coordinate as z.sub.n,s,i=N.sub.rC.sub.n,s,i+R.sub.n,s,i.
[0508] FIG. 27 illustrates an operation of a twisted row-column
block interleaver according to another embodiment of the present
invention.
[0509] More specifically, FIG. 27 illustrates the interleaving
array in the TI memory for each TI group, including virtual
XFECBLOCKs when N.sub.xBLOCK_TI (0,0)=3, N.sub.xBLOCK_TI (1,0)=6,
N.sub.xBLOCK_TI (2,0)=5.
[0510] The variable number N.sub.xBLOCK_TI (n,s)=N.sub.r will be
less than or equal to N'.sub.xBLOCK_TI_MAX. Thus, in order to
achieve a single-memory deinterleaving at the receiver side,
regardless of N.sub.xBLOCK_TI (n,s), the interleaving array for use
in a twisted row-column block interleaver is set to the size of
N.sub.r.times.N.sub.c=N.sub.cells.times.N'.sub.xBLOCK_TI_MAX by
inserting the virtual XFECBLOCKs into the TI memory and the reading
process is accomplished as follow expression.
TABLE-US-00034 [Math FIG. 11] p = 0; for i = 0; i <
N.sub.cellsN'.sub.xBLOCK.sub.--.sub.TI.sub.--.sub.MAX; i = i + 1
{GENERATE(R.sub.n,s,i, C.sub.n,s,i); V.sub.i = N.sub.rC.sub.n,s,j +
R.sub.n,s,j if V.sub.i < N.sub.cellsN.sub.xBLOCK.sub.--.sub.TI
(n,s) { Z.sub.n,s,p = V.sub.i; p = p + 1; } }
[0511] The number of TI groups is set to 3. The option of time
interleaver is signaled in the PLS2-STAT data by DP_TI_TYPE=`0`,
DP_FRAME_INTERVAL=`1`, and DP_TI_LENGTH=`1`, i.e., NTI=1, IJUMP=1,
and PI=1. The number of XFECBLOCKs, each of which has Ncells=30
cells, per TI group is signaled in the PLS2-DYN data by
NxBLOCK_TI(0,0)=3, NxBLOCK_TI(1,0)=6, and NxBLOCK_TI(2,0)=5,
respectively. The maximum number of XFECBLOCK is signaled in the
PLS2-STAT data by NxBLOCK_Group_MAX, which leads to .left
brkt-bot.N.sub.xBLOCK_GROUP_MAX/N.sub.TI.right
brkt-bot.=N.sub.xBLOCK_TI_MAX=6.
[0512] FIG. 28 illustrates a diagonal-wise reading pattern of a
twisted row-column block interleaver according to an embodiment of
the present invention.
[0513] More specifically FIG. 28 shows a diagonal-wise reading
pattern from each interleaving array with parameters of
N'.sub.xBLOCK_TI_MAX=7 and Sshift=(7-1)/2=3. Note that in the
reading process shown as pseudocode above, if
V.sub.i.gtoreq.N.sub.cellsN.sub.xBLOCK_TI(n,s), the value of Vi is
skipped and the next calculated value of Vi is used.
[0514] FIG. 29 illustrates interleaved XFECBLOCKs from each
interleaving array according to an embodiment of the present
invention.
[0515] FIG. 29 illustrates the interleaved XFECBLOCKs from each
interleaving array with parameters of N'.sub.xBLOCK_TI_MAX=7 and
Sshift=3.
[0516] FIG. 30 is a conceptual diagram illustrating a protocol
stack for the next generation broadcast system based on hybrid
according to an embodiment of the present invention.
[0517] The present invention proposes a data link (encapsulation)
part shown in FIG. 30, and proposes a method for transmitting
MPEG-2 TS (Transport Stream) and/or IP (Internet Protocol) packets
received from an upper layer over a physical layer. In addition,
the present invention provides a signaling transmission method
needed to operate a physical layer. In addition, when transmission
of a new packet type is considered in an upper layer in the future,
the present invention can implement a method for transmitting the
new packet transmission information to a physical layer.
[0518] The corresponding protocol layer may also be referred to as
a data link layer, an encapsulation layer, a Layer 2, or the like.
For convenience of description and better understanding of the
present invention, the protocol layer will hereinafter be referred
to as a link layer. When the term "protocol layer" is actually
applied to the present invention, it should be noted that the term
"protocol layer" may be replaced with the term `link layer` or may
also be called a new name as necessary.
[0519] The broadcast system according to the present invention may
correspond to a hybrid broadcast signal implemented by combination
of an IP (Internet Protocol) centric broadcast network and a
broadband network.
[0520] The broadcast system according to the present invention may
be designed to be compatible with the legacy MPEG-2 based broadcast
system.
[0521] The broadcast system according to the present invention may
correspond to a hybrid broadcast system based on a combination of
the IP centric broadcast network, a broadband network, and/or a
mobile communication network or cellular network.
[0522] Referring to FIG. 30, a physical layer may use a physical
protocol adopted by a broadcast system such as the ATSC and/or DVB
system.
[0523] In an encapsulation layer, an IP datagram may be obtained
from specific information acquired from a physical layer, or the
obtained IP datagram may be converted into a specific frame (e.g.,
RS frame, GSE-lite, GSE or signal frame). In this case, the frame
may include an aggregate of IP datagrams.
[0524] A fast access channel (FAC) may include specific information
(e.g., mapping information between a service ID and a frame) used
for access to a service and/or contents.
[0525] A broadcast system according to the present invention may
use a variety of protocols, for example, Internet Protocol (IP),
User Datagram Protocol (UDP), Transmission Control Protocol (TCP),
ALC/LCT (Asynchronous Layered Coding/Layered Coding Transport),
RCP/RTCP (Rate Control Protocol/RTP Control Protocol), HTTP
(Hypertext Transfer Protocol), FLUTE (File Delivery over
Unidirectional Transport), etc. A stack between protocols may refer
to the structure of FIG. 30.
[0526] In the broadcast system of the present invention, data may
be transmitted in the form of ISOBMFF (ISO base media file format).
ESG (Electrical Service Guide), NRT (Non Real Time), A/V
(Audio/Video) and/or general data may be transmitted in the form of
ISOBMFF.
[0527] Data transmission caused by the broadcast network may
include linear content transmission and/or non-linear content
transmission.
[0528] RTP/RTCP based A/V, and data (closed caption, emergency
alert message, etc.) transmission may correspond to linear content
transmission.
[0529] RTP payload may be encapsulated and transmitted in the form
of an RTP/AV stream including a Network Abstraction Layer (NAL)
and/or in the form of an ISO based media file format. RTP payload
transmission may correspond to linear content transmission. If the
RTP payload is encapsulated and transmitted in the form of an ISO
based media file format, the RTP payload may include MPEG DASH
media segments for A/V or the like.
[0530] FLUTE based ESG transmission, non-timed data transmission,
and NRT content transmission may correspond to non-linear content
transmission. The above-mentioned information may be encapsulated
and transmitted in the form of a MIME type file and/or an ISO based
media file format. If data is encapsulated and transmitted in the
form of an ISO based media file format, this data transmission may
conceptually include an MPEG DASH media segment for A/V or the
like.
[0531] Data transmission over the broadband network may be
classified into transmission of contents and transmission of the
signaling data.
[0532] Content transmission may include transmission of linear
content (A/V, data (closed caption, emergency alert messages,
etc.), transmission of non-linear content (ESG, non-timed data,
etc.), and transmission of an MPEG DASH based Media segment (A/V,
data).
[0533] Transmission of the signaling data may include transmission
of data including a signaling table (including MPD of MPEG DASH)
transmitted on the broadcast network.
[0534] The broadcast system of the present invention may support
not only synchronization between linear/non-linear contents having
been transmitted over the broadcast network, but also
synchronization between content transmitted over the broadcast
network and content transmitted over the broadband network. For
example, if one UD content is divided into the broadcast network
and the broadband network and then simultaneously transmitted over
the broadcast and broadband networks, the receiver may coordinate a
timeline dependent upon a transmission (Tx) protocol, may
synchronize contents of the broadcast network and the broadband
contents, and may reconstruct the synchronized contents into one
piece of UE content.
[0535] An application layer of the broadcast system may implement
technical characteristics, for example, interactivity,
personalization, second screen, ACR (automatic content
recognition), etc. The above-mentioned technical characteristics
are of importance to the North American broadcast standard evolved
from ATSC 2.0 to ATSC 3.0. For example, HTML5 may be used to
implement interactivity.
[0536] In a presentation layer of the broadcast system of the
present invention, HTML and/or HTML may be used to identify the
space and time relationship between components or between
bidirectional applications.
[0537] The broadcast system according to another embodiment may be
implemented by addition or modification of the above-mentioned
broadcast system, and a detailed description of the individual
constituent elements will be replaced with that of the
above-mentioned broadcast system.
[0538] The broadcast system according to another embodiment of the
present invention may include a system structure compatible with
the MPEG-2 system. For example, the linear/non-linear contents
transmitted in the legacy MPEG-2 system can be received or operated
in the ATSC 3.0 system, and the A/V and data processing may be
adaptively coordinated according to whether data received by the
ATSC 3.0 system is an MPEG-2 TS or IP datagram.
[0539] In an encapsulation layer of the broadcast system according
to another embodiment of the present invention, information/data
obtained from a physical layer may be converted into the MPEG-2 TS
or IP datagram, or may be converted into a specific frame (e.g., RS
frame, GSE-lite, GSE or signal frame, etc.) using the IP
datagram.
[0540] The broadcast system according to another embodiment may
include signaling information capable of being adaptively obtained
according to whether MPEG-2 TS or IP datagram is used to acquire
the service/content through the broadcast network. That is, when
obtaining signaling information from the broadcast system, the
signaling information may be obtained on the basis of MPEG-2 TS, or
may be obtained from data based on a UDP protocol.
[0541] The broadcast system of the present invention may support
synchronization between the linear/non-linear contents based on the
broadcast network encapsulated by MPEG-2 TS and/or IP datagram.
Alternatively, the broadcast system can support synchronization
between content fragments that are respectively transmitted through
the broadcast network and the broadband network. For example, if
one UD content is divided into the broadcast network and the
broadband network and then simultaneously transmitted over the
broadcast and broadband networks, the receiver may coordinate a
timeline dependent upon a transmission (Tx) protocol, may
synchronize contents of the broadcast network and the broadband
contents, and may reconstruct the synchronized contents into one
piece of UE content.
[0542] FIG. 31 is a conceptual diagram illustrating an interface of
a link layer according to an embodiment of the present
invention.
[0543] Referring to FIG. 31, the transmitter may consider an
exemplary case in which IP packets and/or MPEG-2 TS packets mainly
used in the digital broadcasting are used as input signals. The
transmitter may also support a packet structure of a new protocol
capable of being used in the next generation broadcast system. The
encapsulated data of the link layer and signaling information may
be transmitted to a physical layer. The transmitter may process the
transmitted data (including signaling data) according to the
protocol of a physical layer supported by the broadcast system,
such that the transmitter may transmit a signal including the
corresponding data.
[0544] On the other hand, the receiver may recover data and
signaling information received from the physical layer into other
data capable of being processed in a higher layer. The receiver may
read a header of the packet, and may determine whether a packet
received from the physical layer indicates signaling information
(or signaling data) or recognition data (or content data).
[0545] The signaling information (i.e., signaling data) received
from the link layer of the transmitter may include first signaling
information that is received from an upper layer and needs to be
transmitted to an upper layer of the receiver; second signaling
information that is generated from the link layer and provides
information regarding data processing in the link layer of the
receiver; and/or third signaling information that is generated from
the upper layer or the link layer and is transferred to quickly
detect specific data (e.g., service, content, and/or signaling
data) in a physical layer.
[0546] FIG. 32 is a conceptual diagram illustrating a packet
structure of a link layer according to an embodiment of the present
invention.
[0547] In accordance with an embodiment of the present invention,
the packet of the link layer may include a fixed header, an
extended header, and/or payload.
[0548] A fixed header is designed to have a fixed size. For
example, the fixed header may be 1 byte long. The extended header
can be changed in size. Payload including data received from the
higher layer may be located behind the fixed header and the
extended header.
[0549] The fixed header may include a packet type element and/or an
indicator part element.
[0550] The packet type element may be 3 bits long. The packet type
element may identify a packet type of a higher layer (i.e., a
higher layer of the link layer). The packet type identified by the
packet type element value will hereinafter be described in
detail.
[0551] The indicator part element may include information regarding
a payload construction method and/or construction information of
the extended header. The construction method and/or the
construction information indicated by the indicator part element
may be changed according to packet types.
[0552] FIG. 33 shows packet types dependent upon the packet type
element values according to an embodiment of the present
invention.
[0553] Referring to FIG. 33, if the packet type element is set to
`000`, this means that a packet transferred from the higher layer
to the link layer is an IPv4 (Internet Protocol version 4)
packet.
[0554] If the packet type element value is set to `001`, this means
that a packet transferred from the higher layer to the link layer
is an IPv6 (Internet Protocol version 6) packet.
[0555] If the packet type element value is set to `010`, this means
that a packet transferred from the higher layer to the link layer
is a Compressed IP packet.
[0556] If the packet type element value is set to `011`, this means
that a packet transferred from the higher layer to the link layer
is an MPEG-2 TS packet.
[0557] If the packet type element value is set to `101`, this means
that a packet transferred from the higher layer to the link layer
is a Packetized Stream packet. For example, the Packetized Stream
may correspond to an MPEG media transport packet.
[0558] If the packet type element value is set to `110`, this means
that a packet transferred from the higher layer to the link layer
is a packet for transmitting signaling information (signaling
data).
[0559] If the packet type element value is set to `111`, this means
that a packet transferred from the higher layer to the link layer
is a Framed Packet type.
[0560] FIG. 34 is a conceptual diagram illustrating a header
structure of a link layer packet when an IP packet is transmitted
to the link layer according to an embodiment of the present
invention.
[0561] Referring to FIG. 34, if the IP packet is input to the link
layer, the packet type element value may be 000B (3 bits of 000) or
001B (3 bits of 001).
[0562] Referring to a packet header of the link layer when an IP
packet is input, the indicator part element located next to the
packet type element may include a C/S (Concatenation/Segmentation)
field and/or an additional bit of 3 bits (hereinafter referred to
as an additional field).
[0563] In case of the packet of the link layer, an additional field
of the fixed header and information of the extended header may be
decided according to the CS (Concatenation/Segmentation) field of 2
bits located behind the packet type element.
[0564] The C/S field indicates the processing type of the input IP
packet, and may include information regarding the extended header
length.
[0565] In accordance with an embodiment of the present invention,
the case in which the C/S field is set to 00B (2 bits of 00) may
indicate that payload of the link layer packet includes a normal
packet. The normal packet may indicate that the input IP packet is
used as payload of the link layer packet without change. In this
case, the additional field of the fixed header part is not in use,
and may be reserved for a subsequent use. In this case, the
extended header may not be used.
[0566] If the C/S field is set to `01B` (2 bits of `01`), this
means that payload of the link layer packet includes a concatenated
packet. The concatenated packet includes one or more IP packets.
That is, one or more IP packets may be contained in payload of the
link layer packet. In this case, the extended header is not used,
and the additional field located subsequent to the C/S field may be
used as the count field. A detailed description of the count field
will hereinafter be described in detail.
[0567] If the C/S field is set to `10B` (2 bits of `10`), this
means that payload is composed of segmented packets. The segmented
packet is obtained by dividing one IP packet into a few segments.
Specifically, the segmented packet may include one segment from
among the divided segments. That is, payload of the link layer
packet may include any one of a plurality of packets contained in
the IP packet. The additional field located behind the C/S field is
used as the segment ID. The segment ID may uniquely identify the
segment. The segment ID is assigned when the IP packet is
segmented. In more detail, if segments to be respectively
transmitted in the future are integrated, the segment ID can
indicate the presence of a constituent element of the same IP
packet. The segment ID may be 3 bits long, and at the same time can
support segmentation of the IP packet. For example, the divided
segments obtained by one IP packet may have the same segment ID. In
this case, the extended header may be 1 byte long. In this case,
the extended header may include the Seg_SN (Segment Sequence
Number) field and/or the Seg_Len_ID (Segment Length ID)
FIELD
[0568] The Seg_SN field may be 4 bits long, and may indicate a
sequence number of the corresponding segment for use in the IP
packet. When the Seg_SN field IP packet is segmented, the Seg_SN
field may be used to confirm the order or sequence of each segment.
Accordingly, although the link layer packets including a payload
segmented from one IP packet may have the same segment ID (Seg_ID),
the link layer packets may have different Seg_SN field values. The
Seg_SN field may be 4 bits long. In this case, one IP packet can be
segmented into a maximum of 16 segments. If a user desires to
divide the IP packet into many more segments, the Seg_SN field is
increased in size so that the Seg_SN field may indicate each order
of the segment and/or the number of segments.
[0569] The Seg_Len_ID (Segment Length ID) field may be 4 bits long,
and may be used to identify the segment length. The actual segment
length according to the Seg_Len_ID field value may be identified by
a table to be described later. If the length value of an actual
segment is signaled instead of the Seg_Len_ID field, the Seg_Len_ID
field of 4 bits may be extended to the segment length field of 12
bits. In this case, the extended header of 2 bytes may be contained
in the link layer packet.
[0570] If the C/S field value is set to 11B (2 bits of `11`), this
means an exemplary case in which payload includes the segmented
packet as in the case in which the C/S field value is set to 10B.
However, the C/S field of 11B may also indicate that the last
segment from among several segments divided in one IP packet may be
contained in a payload. When segments are collected to reconstruct
one IP packet, the receiver may identify the link layer packet
configured to transmit the last segment using the C/S field value,
and the segment contained in the payload of the corresponding
packet may be recognized as the last segment. The additional field
located behind the C/S field may be used as the segment ID. In this
case, the extended header may be 2 bytes long. The extended header
may include the Seg_SN (Segment Sequence Number) field and/or the
L_Seg_Len (Last Segment Length)
FIELD
[0571] The L_Seg_Len field may indicate the actual length of the
last segment. If data is segmented to generate the same-sized data
segments in the order from the front part of the IP packet using
the Seg_Len_ID field, the last segment may have a different size as
compared to another previous segment. Accordingly, the segment
length may be directly indicated using the L_Seg_Len field. The
segment length may be changed according to the number of allocated
bits of the L_Seg_Len field. However, when allocating the number of
bits according to the present invention, the L_Seg_Len field may
indicate that the last segment is 1.about.4095 bytes long.
[0572] That is, if one IP packet is divided into a plurality of
segments, the IP packet can be divided into a plurality of segments
having a predetermined length. However, the length of the last
segment may be changed according to the length of the IP packet.
Accordingly, the length of the last segment needs to be signaled
independently. A detailed description of the field having the same
name may be replaced with the above-mentioned description.
[0573] FIG. 35 is a conceptual diagram illustrating the meaning and
header structures according to C/S field values.
[0574] Referring to FIG. 35, if the C/S field is set to `00`, this
means that a normal packet is contained in the payload of the link
layer packet and the additional field is reserved. On the other
hand, the extended header may not be contained in the link layer
packet. In this case, a total length of the header of the link
layer packet may be 1 byte.
[0575] If the C/S field is set to `01`, a concatenated packet is
contained in the payload of the link layer packet and the
additional field may be used as the count field. A detailed
description of the count field will be given later. In the
meantime, the extended header may not be contained in the link
layer packet. In this case, a total length of the header of the
link layer packet may be 1 byte.
[0576] If the C/S field is set to `10`, the segmented packet may be
contained in the payload of the link layer packet, and the
additional field may be used as the segment ID. In the meantime,
the extended header may be contained in the link layer packet, and
the extended header may include the Seg_SN field and/or the
Seg_Len_ID field. A detailed description of the Seg_SN field or the
Seg_Len_ID field may be replaced with the above-mentioned
description or a description to be given later. A total length of
the link layer packet may be 2 bytes.
[0577] If the C/S field is set to `11`, the segmented packet (i.e.,
packet including the last segment) may be contained in the payload
of the link layer packet, and the additional field may be used as
the segment ID. Meanwhile, the extended header may be contained in
the link layer packet, and the extended header may include the
Seg_SN field and/or the L_Seg_Len field. A detailed description of
the Seg_SN field or the L_Seg_Len field may be replaced with the
above-mentioned description or a description to be described given.
A total length of the link layer packet may be 3 bytes.
[0578] FIG. 36 is a conceptual diagram illustrating the meaning
according to the count field values.
[0579] Referring to FIG. 36, the count field may be used in the
case in which the payload of the link layer packet includes a
concatenated packet. The count field may indicate how many IP
packets are contained in one payload. The value of the count field
may indicate the number of concatenated IP packets. However, zero
or one concatenation has no meaning, such that the count field may
indicate that the IP packets, the number of which is denoted by
"count field value+2", are contained in the payload. In accordance
with one embodiment, 3 bits may be allocated to the count field, so
that this means that a maximum of 9 IP packets has been contained
in the payload of the link layer packet. If there is a need to
include many more IP packets in one payload, the length of the
count field may be extended, or 9 or more IP packets of the
extended header may be additionally signaled.
[0580] FIG. 37 is a conceptual diagram illustrating the meaning and
segment lengths according to values of Seg_Len_ID field.
[0581] Referring to FIG. 37, the Seg_Len_ID field may be used to
indicate the length of segments other than the last segment from
among several segments. In order to reduce overhead of the header
needed for indicating the segment length, an available segment size
may be limited to 16 segments.
[0582] The segment length is decided in response to the packet
input size predetermined by a code rate of Forward Error Correction
(FEC) processed by a physical layer, and the decided segment length
may be designated as a length for each value of the Seg_Len_ID
field. For example, in association with each value assigned to the
Seg_Len_ID field, the segment length may be predetermined. In this
case, information regarding the segment length dependent upon each
value of the Seg_Len_ID field is generated by the transmitter and
transmitted to the receiver, such that the receiver may store the
received information therein. In the meantime, the segment length
established to have each value of the Seg_Len_ID field may be
changed. In this case, the transmitter may generate new information
and transmit the new information to the receiver, and the receiver
may update stored information on the basis of the above new
information.
[0583] In the meantime, if the physical layer processing is
performed irrespective of the segment length, the segment length
may be calculated as shown in the equation of FIG. 37.
[0584] In Equation of FIG. 37, Len_Unit (Length Unit) may be a
basic unit for indicating the segment length, and min_Len may be a
minimum value of the segment length. Len_Unit and min_Len may be
set to the same value not only in the transmitter but also in the
receiver. After the above-mentioned parameters of Equation have
been decided once, it is preferable that the above parameters
remain unchanged in terms of system throughput. This value may be
decided in consideration of the FEC processing throughput of the
physical layer during an initiation process of the system. For
example, as shown in FIG. 37, the Len_Unit or min_Len value may
indicate the segment length differently represented in response to
the Seg_Len_ID field value. At this time, the parameter `Len_Unit`
may be 256, and the parameter `min_Len` may be 512.
[0585] FIG. 38 is a conceptual diagram illustrating an equation for
encapsulating a normal packet and an equation for calculating a
link layer packet length.
[0586] Referring to FIG. 38, if the input IP packet is not
concatenated or segmented within the processing range of the
physical layer as described above, the IP packet may be
encapsulated into a normal packet. The following contents may be
equally applied to IPv4 and IPv6 IP packets. One IP packet may be
used as payload of the link layer packet without change, the packet
type element value may be set to 000B (IPv4) or 001B (IPv6), and
the C/S field value may be set to 00B (Normal Packet). The
remaining three bits of the fixed header may be set to a reserved
field to be used for another usage in future.
[0587] The link layer packet length can be identified as follows. A
specific field indicating the IP packet length may be contained in
the header of the IP packet. The field indicating the length is
always located at the same position, such that the receiver may
confirm the field located at a specific position spaced apart from
an initial part (start part) of the link layer packet by a
predetermined offset, such that the payload length of the link
layer packet can be recognized.
[0588] The receiver can read the length field having the length of
2 bytes at a specific position spaced apart from the start point of
the payload by 2 bytes in case of IPv4, and can read the length
field having the length of 2 bytes at a specific position spaced
apart from the start point of the payload by 4 bytes in case of
IPv6.
[0589] Referring to FIG. 38, assuming that the IPv4 length field is
set to LIPv4, LIPv4 indicates a total length of IPv4. In this case,
if the header length LH (1 byte) of the link layer packet is added
to LIPv4, the length of the entire link layer packet is obtained.
In this case, LT may indicate the length of the link layer
packet.
[0590] Referring to the equation of FIG. 38, assuming that the IPv6
length field is denoted by LIPv6, LIPv6 indicates only the payload
length of the IPv6 IP packet. Accordingly, if the header length LH
(1 byte) of the link layer packet is added and the fixed header
length (40 bytes) of IPv6 is additionally added, the length of the
link layer packet is obtained. Here, LT may denote the length of
the link layer packet.
[0591] FIG. 39 is a conceptual diagram illustrating a process for
encapsulating a concatenated packet and an equation for calculating
a link layer packet length.
[0592] Referring to FIG. 39, if the input IP packet does not arrive
within the processing range of the physical layer, some IP packets
are concatenated and encapsulated into one link layer packet. The
following description can also be applied to IP packets of IPv4 and
IPv6.
[0593] Some IP packets may be used as the payload of the link layer
packet, the packet type element value may be set to 000B (IPv4) or
001B (IPv6), and the C/S field may be set to 01B (Concatenated
Packet). In addition, the count field of 3 bits indicating how many
IP packets are contained in one payload may be concatenated to the
C/S field of 01B.
[0594] In order to calculate the length of the concatenated packet
by the receiver, a similar way to the normal packet case may be
used. Assuming that the number of concatenated IP packets indicated
by the count field is denoted by n, the header length of the link
layer packet is denoted by LH, and the length of each IP packet is
denoted by Lk (where 1.ltoreq.k.ltoreq.n), the entire link layer
packet length (LT) can be calculated as shown in the equation.
[0595] Since the concatenated packet has the fixed header
information only, LH=1 (byte) is achieved, and each Lk (where
1.ltoreq.k.ltoreq.n) value can be confirmed by reading the value of
the length field contained in the header of each IP packet
contained in the concatenated packet. The receiver may parse the
length field of a first IP packet at a specific position that has a
predetermined offset on the basis of a payload start position after
the link layer packet header has ended, and may identify the length
of a first IP packet using this length field. The receiver may
parse the length field of a second IP packet at a specific position
that has a predetermined offset on the basis of a length end point
of the first IP packet, and may identify the length of the second
IP packet using this length field. The above-mentioned operation is
repeated a predetermined number of times corresponding to the
number of IP packets contained in the payload of the link layer
packet, so that the paylaod length of the link layer packet can be
identified.
[0596] FIG. 40 is a conceptual diagram illustrating a process for
calculating the length of a concatenated packet including an IPv4
packet and an equation for calculating an offset value at which a
length field of the IP packet is located.
[0597] When the IP packet is input to the transmitter, the
transmitter has no difficulty in reading the length field of the IP
packet. However, the receiver can recognize only the number of IP
packets constructing the link layer packet through the header, such
that the position of each length field is not well known in the
art. However, since the length field is always located at the same
position of the header of the IP packet, the position of the length
field is detected using the following method, so that the length of
each IP packet contained in the payload of the concatenated packet
can be calculated and recognized.
[0598] Assuming that n IP packets contained in the payload of the
concatenated packet are respectively denoted by IP1, IP2, . . . ,
IPk, . . . , IPn, the position of the length field corresponding to
IPk may be spaced apart from a start point of the payload of the
concatenated packet by Pk bytes. In this case, Pk (where
1.ltoreq.k.ltoreq.n) may be an offset value at which the length
field of the k-th IP packet is located on the basis of a start
point of the payload of the concatenated packet, and the Pk value
can be calculated as shown in the equation of FIG. 40.
[0599] In this case, P1 of the IPv4 packet is 2 bytes. Therefore,
the Pk value is successively updated from P1, and the Lk value
corresponding to the Pk value is read. If Lk is applied to the
equation of FIG. 39, the length of concatenated packet can be
finally calculated.
[0600] FIG. 41 is a conceptual diagram illustrating a process for
calculating the length of a concatenated packet including an IPv6
packet and an equation for calculating an offset value at which a
length field of the IP packet is located.
[0601] If the IPv6 packets are concatenated and contained in the
payload of the link layer packet, a method for calculating the
payload length is as follows. The length field contained in the
IPv6 packet indicates information regarding the payload length of
the IPv6 packet, and 40 bytes indicating the length of a fixed
header of IPv6 are added to the payload length of the IPv6 packet
indicated by the length field, such that the length of IPv6 packet
can be calculated.
[0602] Assuming that n IP packets contained in the payload of the
concatenated packet are respectively denoted by IP1, IP2, . . . ,
IPk, . . . , IPn, the position of the length field corresponding to
IPk may be spaced apart from the start position of the payload of
the concatenated packet by Pk bytes. In this case, Pk (wherein
1.ltoreq.k.ltoreq.n) may be an offset value at which the length
field of the k-th IP packet is located on the basis of a start
point of the payload of the concatenated packet, and may be
calculated by the equation shown in FIG. 41. In this case, P1 in
case of IPv6 has 4 bytes. Accordingly, the Pk value is successively
updated from P1, and Lk corresponding to the Pk value is read. If
this Lk value is applied to the equation of FIG. 39, the length of
concatenated packet can be finally calculated.
[0603] FIG. 42 is a conceptual diagram illustrating an
encapsulation process of a segmented packet according to an
embodiment of the present invention.
[0604] The following description can be equally be applied to the
IPv4 IP packet and the IPv6 IP packet. One IP packet is segmented
to result in a payload of several link layer packets. The packet
type element value may be set to 000B (IPv4) or 001B (IPv6), and
the C/S field value may be 10B or 11B according to the segment
construction.
[0605] The C/S field may be set to 11B only in a specific segment
corresponding to the last part of the IP packet, and may be set to
10B in the remaining segments other than the above specific
segment. The C/S field value may also indicate information of the
extended header of the link layer packet as described above. That
is, if the C/S field is set to 10B, the header is 2 bytes long. If
the C/S field is set to 11B, the header is 3 bytes long.
[0606] In order to indicate the segmentation state from the same IP
packet, the Seg_ID (segment ID) values contained in the headers of
the individual link layer packets must have the same value. In
order to allow the receiver to indicate the order (sequence)
information of segments for recombination of normal IP packets, the
sequentially increasing Seg_SN values are recorded in the header of
each link layer packet.
[0607] When the IP packet is segmented, the segment length is
decided as described above, and the segmentation process based on
the same length is carried out. Thereafter, the Seg_Len_ID value
appropriate for the corresponding length information is recorded in
the header. In this case, the length of the last segment may be
changed as compared to the previous segment, so that the length
information may be directly designated using the L_Seg_Len
field.
[0608] The length information designated by the Seg_Len_ID field
and the L_Seg_Len field may indicate only payload information of
the segment (i.e., link layer packet), such that the receiver may
identify the length information of the entire link layer packet by
adding the header length of the link layer packet to the payload
length of the link layer packet using the C/S field.
[0609] FIG. 43 is a conceptual diagram illustrating a segmentation
process of an IP packet and header information of a link layer
packet according to an embodiment of the present invention.
[0610] When the IP packet is segmented and encapsulated into the
link layer packet, the field values allocated to the header of
respective link layer packets are shown in FIG. 14.
[0611] For example, if the IP packet having the length of 5500
bytes in the IP layer is input to the link layer, this IP packet is
divided into 5 segments (S1, S2, S3, S4, S5), and headers (H1, H2,
H3, H4, H5) are added to the 5 segments, so that the added results
are encapsulated into the individual link layer packets.
[0612] Assuming that the case of using the IPv4 packet is used, the
packet type element value may be set to 000B. The C/S field value
is set to 10B in the range of H1.about.H4, and the C/S field value
of H5 is set to 11B. All the segment IDs (Seg_IDs) indicating the
same IP packet structure may be set to 000B, and the Seg_SN field
is sequentially denoted by 0000B.about.0100B in the range of
H1.about.H5.
[0613] The resultant value obtained when 5500 bytes is divided by 5
is 1100 bytes. Assuming that the segment is composed of the length
of 1024 bytes located closest to the 1100 bytes, the length of the
last segment S5 is denoted by 1404 bytes (010101111100B). In this
case, the Seg_Len_ID field may be set to 0010B as shown in the
above-mentioned example.
[0614] FIG. 44 is a conceptual diagram illustrating a segmentation
process of an IP packet including a cyclic redundancy check (CRC)
according to an embodiment of the present invention.
[0615] When the IP packet is segmented and transmitted to the
receiver, the transmitter may attach the CRC to the rear of the IP
packet in such a manner that integrity of combined packets can be
confirmed by the receiver, and finally the segmentation process may
be carried out. Generally, since CRS is added to the last part of
the packet, the CRS is contained in the last segment after
completion of the segmentation process.
[0616] When the receiver receives data having a length exceeding
the length of the last segment, the received data may be recognized
as CRC. Alternatively, the length including the CRC length may be
signaled as the length of the last segment.
[0617] FIG. 45 is a conceptual diagram illustrating a header
structure of a link layer packet when MPEG-2 TS (Transport Stream)
is input to a link layer according to an embodiment of the present
invention.
[0618] The packet type element may identify that the MPEG-2 TS
packet is input to the link layer. For example, the packet type
element value may be set to 011B.
[0619] If the MPEG-2 TS is input, the header structure of the link
layer packet is shown in FIG. 16. If the MPEG-2 TS packet is input
to the link layer, the header of the link layer packet may include
the packet type element, the count field, the PI (PID Indicator)
field, and/or the DI (Deleted Null Packet Indicator) field.
[0620] For example, the 2-bit or 3-bit count field, the 1-bit PI
(PID Indicator) field, and the 1-bit DI (Deleted Null Packet
Indicator) field may be arranged subsequent to the packet type of
the header of the link layer packet. If the count field has 2 bits,
the remaining 1 bit may be used as a reserved field to be used for
a subsequent use in future. The fixed header part may be
constructed in various ways as shown in FIGS. 16(a) to 16(d)
according to locations of the reserved field. Although the present
invention will be disclosed on the basis of the header of (a) for
convenience of description and better understanding of the present
invention, the same description may also be applied to other types
of headers.
[0621] If the MPEG-2 TS packet is input to the link layer (packet
type=011), the extended header may not be used.
[0622] The count field may indicate how many MPEG-2 TS packets are
contained in the payload of the link layer packet. The size of one
MPEG-2 TS packet is greatly less than the size of LDPC (Low-density
parity-check) input indicating the FEC scheme having a
high-selection possibility in the physical layer of the next
generation broadcast system, and concatenation of the link layer
can be basically considered. That is, one or more MPEG-2 TS packets
may be contained in the payload of the link layer packet. However,
the number of concatenated MPEG-2 TS packets is limited to some
numbers, so that this information may be identified by 2 bits or 3
bits. Since the length of the MPEG-2 T packet is fixed to a
predetermined size (e.g., 188 bytes), the receiver may also
estimate the payload size of the link layer packet using the count
field. An example of indicating the number of MPEG-2 TS packets
according to the count field will hereinafter be described in
detail.
[0623] PI (Common PID indicator) field is set to `1` when the
MPEG-2 TS packets contained in the payload of one link layer packet
have the same PIDs (Packet Identifiers). On the contrary, if the
MPEG-2 TS packets contained in the payload of one link layer packet
have different PIDs, the PI field is set to `0`. The PID field may
be 1 bit long.
[0624] DI (Null Packet Deletion Indicator) field is set to 1 when a
null packet contained in the MPEG-2 TS packet and then transmitted
is deleted. If the null packet is not deleted, the DI field is set
to `0`. The DI field may be 1 bit long. If the DI field is set to
1, the receiver may reuse some fields of the MPEG-2 TS packet so as
to support null packet deletion in the link layer.
[0625] FIG. 46 shows the number of MPEG-2 TS packets contained in a
payload of the link layer packet according to values of a count
field.
[0626] If the count field is 2 bits long, the concatenated MPEG-2
TS packets may be present in four cases. The payload size of the
link layer packet other than synchronous bytes (Sync Bytes) (47H)
may also be identified by the count field.
[0627] The number of MPEG-2 TS packets to be allocated according to
the count field value may be changed according to system
designers.
[0628] FIG. 47 is a conceptual diagram illustrating a header of the
MPEG-2 TS packet according to an embodiment of the present
invention.
[0629] Referring to FIG. 47, the header of the MPEG-2 TS packet may
include a Sync Byte field, a Transport Error Indicator field, a
payload unit start indicator field, a transport priority field, a
PID field, a transport scrambling control field, an adaptation
field control field, and/or a continuity counter field.
[0630] The Sync Byte field may be used for packet synchronization,
and may be excluded in the case of encapsulation at the link layer.
A transport error indicator (EI) located next to the Sync Byte
field is not used by the transmitter, and may be used to inform a
higher layer of the presence of an error incapable of being
recovered by the receiver. As a result, the Transport Error
Indicator field is not used by the transmitter.
[0631] The Transport Error Indicator field is established in a
demodulation process on the condition that it is impossible to
correct errors of the stream. In more detail, the Transport Error
Indicator field may indicate the presence of errors incapable of
being corrected in the packet.
[0632] The payload unit start indicator field may identify whether
PES (Packetized elementary stream) or PSI (Program-specific
information) is started.
[0633] The transport priority field may indicate whether the
corresponding packet has a higher priority than other packets
having the same PID.
[0634] The PID field may identify each packet.
[0635] The transport scrambling control field may indicate whether
or not a scramble is used, and/or may indicate whether a scramble
is used using an odd or even key.
[0636] The adaptation field control field may indicate the presence
or absence of the adaptation field.
[0637] The continuity counter field may indicate an order number
(or sequence number (of the payload packet.
[0638] FIG. 48 is a conceptual diagram illustrating a process for
allowing a transceiver to change a usage of a transport error
indicator field according to an embodiment of the present
invention.
[0639] If the DI field is set to 1, the Transport Error Indicator
field may be used as a Deletion Point Indicator (DPI) field in the
link layer of the transmitter as shown in FIG. 19. The Deletion
Point Indicator (DPI) field may be recovered to the Transport Error
Indicator field after completion of the null packet-related
processing in the link layer of the receiver. That is, the DI field
may indicate whether the null packet is deleted, and at the same
time may indicate whether the usage of the Transport Error
Indicator field of the MPEG-2 TS header is changed.
[0640] FIG. 49 is a conceptual diagram illustrating an
encapsulation process of the MPEG-2 TS packet according to an
embodiment of the present invention.
[0641] Basically, the MPEG-2 TS packet concatenation is being
considered, so that a plurality of MPEG-2 TS packets may be
contained in the payload of one link layer packet, and the number
of MPEG-2 TS packets may be decided as described above. Assuming
that the number of MPEG-2 TS packets contained in payload of one
link layer packet is denoted by N, respective MPEG-2 TS packets may
be denoted by Mk (wherein 1.ltoreq.k.ltoreq.n).
[0642] The MPEG-2 TS packet may include a fixed header of 4 bytes
and a payload of 184 bytes. 1 byte from among the header of 4 bytes
is used as the Sync Byte, and is always assigned the same value
(47H). Accordingly, one MPEG-2 TS packet `Mk` may include the sync
part (S) of 1 byte, a fixed header part (Hk) of 3 bytes other than
the sync byte, and/or the payload part (Pk) of 184 bytes (wherein
1.ltoreq.k.ltoreq.n).
[0643] If the adaptation field is used in the header of the MPEG-2
TS packet, the fixed header part is extended even to the front part
of the adaptation field, and the remaining adaptation parts are
contained in the payload part.
[0644] Assuming that N MPEG-2 TS packets are denoted by [M1, M2,
M3, . . . , Mn], the N MPEG-2 TS packets are arranged in the form
of [S, H1, P1, S, H2, P2, . . . , S, Hn, Pn]. The Sync Part is
always set to the same value, such that the receiver can detect the
corresponding position without receiving any signal from the
transmitter, and can perform the insertion action at the detected
position. Accordingly, when the payload of the link layer packet is
constructed, the sync part is excluded so that the packet can be
reduced in size. When an aggregate of the MPEG-2 TS packets having
the above arrangement is constructed as the payload of the link
layer packet, the sync part is excluded, and the header part and
the payload part are separated from each other, so that the MPEG-2
TS packets are arranged in the form of [H1, H2, . . . , Hn, P1, P2,
. . . , Pn].
[0645] If the PI field value is set to zero `0` and the DI field is
set to zero `0`, the payload length of the link layer packet has
`(n.times.3)+(n.times.184)` bytes. Thereafter, if 1 byte indicating
the header length of the link layer packet is added to the
resultant bytes, the entire link layer packet length can be
calculated and obtained. That is, the receiver can identify the
length of the link layer packet through the above-mentioned
process.
[0646] FIG. 50 is a conceptual diagram illustrating an
encapsulation process of the MPEG-2 TS packet having the same PID
according to an embodiment of the present invention.
[0647] If broadcast data is being successively streamed, the MPEG-2
TSs contained in one link layer packet may have the same PDI value.
In this case, repeated PID values are simultaneously indicated so
that the link layer packet can be reduced in size. In this case,
the PI (PID indicator) field contained in the header of the link
layer packet may be used as necessary.
[0648] The PI (Common PID Indicator) value of the header of the
link layer packet may be set to `1`. As described above, in the
case of using N MPEG-2 TS packets [M1, M2, M3, . . . , Mn] within
the payload of the link layer packet, the sync part is excluded,
and the header part and the payload part are separated from each
other, so that the MPEG-2 TS packets may be arranged in the form of
[H1, H2, . . . , Hn, P1, P2, . . . , Pn]. In this case, the header
parts [H1, H2, . . . , Hn] of the MPEG-2 TS may have the same PID.
Although the PID value is indicated and transmitted only once, the
receiver can recover the corresponding data to an original header.
Assuming that a common PID is referred to as a Common PID (CPID)
and the header obtained when the PID is excluded from the MPEG-2 TS
packet header (Hk) is denoted by H'k (where 1.ltoreq.k.ltoreq.n),
the header parts [H1, H2, . . . , Hn] of the MPEG-2 TS constructing
the payload of the link layer packet may be reconstructed in the
form of [CPID, H'1, H'2, . . . , H'n]. This process may be referred
to as Common PID reduction.
[0649] FIG. 51 is a conceptual diagram illustrating an equation for
calculating the length of a link layer packet through a Common PID
reduction process and a Common PID reduction process.
[0650] Referring to FIG. 51, the header part of the MPEG-2 TS
packet may include a PID of 13 bits. If the MPEG-2 TS packets
configured to construct the payload of the link layer packet have
the same PID values, PID is repeated a predetermined number of
times corresponding to the number of concatenated packets.
Accordingly, the PID part is excluded from the header parts [H1,
H2, . . . , Hn] of the original MPEG-2 TS packet, so that the
MPEG-2 TS packets are reconstructed in the form of [H'1, H'2, . . .
, H'n], the common PID value is set to the CPID value, and the CIPD
may be located at the front of the reconstructed header part.
[0651] The PID value has the length of 13 bits, and the stuffing
bit may be added in a manner that the entire packet is configured
in the form of a byte unit. The stuffing bits may be located at the
front or rear part of the CPID. The stuffing bits may be properly
arranged according to the structure of concatenated protocol layer
or the system implementation.
[0652] In the case of encapsulating the MPEG-2 TS packets having
the same PID, the PID is excluded from the header part of the
MPEG-2 TS packets and then encapsulated, and the payload length of
the link layer packet can be calculated as described above.
[0653] As shown in FIG. 51, the header of the MPEG-2 TS packet
other than the Sync Byte is 3 bytes long. If the PID part of 13
bits is excluded, resulting in the implementation of 11 bits.
Accordingly, if N packets are concatenated to implement
(n.times.11) bits, and if the number of concatenated packets is set
to a multiple of 8, the (n.times.11) bits have the length of a byte
unit. The stuffing bits having the length of 3 bits are added to
the common PID length of 13 bits, so that the CPID part having the
length of 2 bytes can be constructed.
[0654] Therefore, in the case of using the link layer packet
obtained when N MPEG-2 TS packets having the same PID are
encapsulated, assuming that the length of the header of the link
layer packet is denoted by LH, the CPID part has the length of
LCPID, and a total length of the link layer packet is denoted by
LT, the LT value can be calculated as shown in the equation of FIG.
51.
[0655] In the embodiment of FIG. 21, LH is 1 byte, and LCPID is 2
bytes.
[0656] FIG. 52 is a conceptual diagram illustrating the number of
concatenated MPEG-2 TS packets and the length of a link layer
packet according to count field values when Common PID reduction is
used.
[0657] If the number of concatenated MPEG-2 TS packets is decided,
and if all packets have the same PID, the above-mentioned common
PID reduction process can be applied, and the receiver can
calculate the length of the link layer packets according to the
above-mentioned equation.
[0658] FIG. 53 is a conceptual diagram illustrating a process for
encapsulating the MPEG-2 TS packet including a null packet
according to an embodiment of the present invention.
[0659] In order to transmit the MPEG-2 TS packet at a fixed
transfer rate, the null packet may be contained in the transmission
(Tx) stream. The null packet is used as overhead in terms of a
transmission aspect, and thus, although the transmitter does not
the null packet, the receiver can recover this null packet. When
the transmitter deletes the null packet and transmits data and the
receiver searches for the number of deleted null packets and the
location of deleted null packets so as to perform data recovery,
the null packet deletion indicator (DI) field located in the header
of the link layer packet may be used. In this case, the DI value of
the header of the link layer packet may be set to 1.
[0660] The encapsulation action when the null packet is located at
an arbitrary position between input Tx streams may be carried in a
manner that n packets other than the null packet are sequentially
concatenated. The count value indicating how many null packets are
successively excluded may be contained in the payload of the link
layer packet, and the receiver may generate the null packet at an
original position on the basis of this count value so that the
original position is filled with the null packet.
[0661] Assuming that N MPEG-2 TS packets other than the null packet
are denoted by [M1, M2, M3, . . . , Mn], the null packet may appear
at any position between the MPEG-2 TS packets (M1.about.Mn). The
part at which the null packet is counted a predetermined number of
times from among 0 n times may appear in a single link layer
packet. That is, assuming that the appearance number of times of
the above part at which the null packet is counted within one link
layer packet is denoted by `p`, the range of p is denoted by 0 to
n.
[0662] If the count value of each null packet is denoted by Cm, the
range of m is denoted by 1.ltoreq.m.ltoreq.p, and Cm does not exist
in case of p=0. Specific information indicating where each Cm is
located between the MPEG-2 TS packets may be denoted using a
specific field in which the usage of EI (transport error indicator)
is changed to DPI (Deletion Point Indicator) in the header of the
MPEG-2 TS packet.
[0663] In the present invention, Cm may have the length of 1 byte.
If the packet to be used later has a margin in length, the 1-byte
Cm may also be extended. Cm of 1 byte may count a maximum of 256
null packets. The indicator field of the null packets is located at
the header of the MPEG-2 TS packet, and the exclusion of a
predetermined number of null packets corresponding to "(value
denoted by Cm)+1" can be calculated. For example, in case of Cm=0,
one null packet may be excluded. In case of Cm=123, 124 null
packets are excluded. If the number of contiguous null packets is
higher than 256, the 257-th null packets are processed as normal
packets, and the subsequent null packets can be processed as such
null packets according to the above-mentioned method.
[0664] As shown in FIG. 24, the null packet is located between the
MPEG-2 TS packets corresponding to Mi and Mi+1. The count value of
the MPEG-2 TS packets is denoted by C1, and the null packet is
located between the MPEG-2 TS packets corresponding to Mj and Mj+1.
If the count value of the MPEG-2 TS packets may be denoted by Cp,
the actual transmission order may be denoted by [ . . . , Mi, C1,
Mi+1, . . . , Mj, Cp, Mj+1, . . . ].
[0665] When the header part and the payload part of the MPEG-2 TS
packet, instead of the null packet, are separated from each other
and rearranged to construct the payload of the link layer packet,
the count value Cm (1.ltoreq.m.ltoreq.p) of the null packets is
located between the header part and the payload part of the MPEG-2
TS packet. That is, the payload of the link layer packets are
arranged in the form of [H1, H2, . . . , Hn, C1, . . . , Cp, P1,
P2, . . . , Pn], and the receiver confirms the count value one byte
by one byte in the order shown in the DPI field located at Hk, and
recovers as many null packets as the number of confirmed value
according to the order of original MPEG-2 TS packets.
[0666] FIG. 54 is a conceptual diagram illustrating a step for
processing an indicator configured to count a removed null packet
and an equation for calculating the length of a link layer packet
in the processing step.
[0667] The DPI field may be established to indicate deletion of the
null packet and the presence of a count value associated with the
deleted null packet. As shown in FIG. 25, if the DPI field present
at Hi from among the header of a plurality of MPEG-2 TS packets is
set to 1, this means that the null packet located between Hi and
Hi+1 is excluded and encapsulated, and its associated 1-byte count
value is located between the header part and the payload part.
[0668] In the above-mentioned process, the length of the link layer
packet can be calculated by the equation shown in FIG. 54.
Therefore, in case of the link layer packet that has been obtained
by encapsulation of n MPEG-2 TS packets through the null packet
exclusion process, assuming that the header length of the link
layer packet is denoted by LH, the count value Cm
(1.ltoreq.m.ltoreq.p) of the null packets is denoted by LCount, and
the total length of the link layer packet is denoted by LT, LT can
be calculated by the equation of FIG. 54.
[0669] FIG. 55 is a conceptual diagram illustrating a process for
encapsulating the MPEG-2 TS packet including a null packet
according to another embodiment of the present invention.
[0670] In accordance with another embodiment of the encapsulation
method excluding the null packets, payload of the link layer packet
can be constructed. In accordance with another embodiment of the
present invention, when the header part and payload part of the
MPEG-2 TS packets are rearranged to construct the link layer packet
payload, the count value Cm (1.ltoreq.m.ltoreq.p) of the null
packets can be located at the header part and the order or sequence
of the null packets may remain unchanged. That is, the count value
of the null packets may be contained at a specific point at which
individual MPEG-2 TS headers are ended. Accordingly, when the
receiver reads a value of the DPI field contained in each MPEG-2 TS
header, the receiver determines completion of the deletion of null
packets, the receiver reads the count value contained at the last
part of the corresponding header, and regenerates as many null
packets as the corresponding count value, such that the regenerated
null packets may be contained in the stream.
[0671] FIG. 56 is a conceptual diagram illustrating a process for
encapsulating the MPEG-2 TS packets including the same packet
identifiers (PIDs) in a stream including a null packet according to
an embodiment of the present invention.
[0672] The encapsulation process of MPEG-2 TS packets including the
same PID (packet identifier) in the stream including the null
packet may be carried out by combination of a first process for
encapsulating the link layer packets other than the above null
packets and a second process for encapsulating the MPEG-2 TS
packets having the same ID into the link layer packet.
[0673] Since an additional PID indicating the null packet is
allocated, the case in which the null packet is contained in the
actual transmission stream is not processed by the same PID.
However, after completion of the exclusion process of the null
packets, only the count value related to the null packet is
contained in the payload of the link layer packet, the remaining N
MPEG-2 TS packets have the same PID, such that the N MPEG-2 TS
packets can be processed by the above-mentioned method
[0674] FIG. 57 is a conceptual diagram illustrating an equation for
calculating the length of a link layer packet when the MPEG-2 TS
packets having the same PIDs are encapsulated in a stream including
a null packet according to an embodiment of the present
invention.
[0675] In the stream including the null packet, when MPEG-2 TS
packets having the same PID are encapsulated, the length of the
link layer packet can be calculated through FIG. 51 and/or FIG. 54.
The above equations can be represented by an equation of FIG.
28.
[0676] FIG. 58 is a conceptual diagram illustrating a link layer
packet structure for transmitting signaling information according
to an embodiment of the present invention.
[0677] In order to transmit signaling information before the
receiver receives the IP packet or the MPEG-2 TS packet in the same
manner as in the update process of IP header compression
information or broadcast channel scan information, the present
invention provides packet formats capable of transmitting signaling
data (i.e., signaling data) to the link layer.
[0678] In accordance with the embodiment of the present invention,
if the packet type element contained in the header of the link
layer packet is set to 110B, a section table (or a descriptor) for
signaling may be contained in the payload of the link layer packet
and then transmitted. The signaling section table may include a
signaling table/table section contained in conventional DVB-SI
(service information), PSI/PSIP, NRT (Non Real Time), ATSC 2.0, and
MH (Mobile/Handheld).
[0679] FIG. 59 is a conceptual diagram illustrating a link layer
packet structure for transmitting the framed packet according to an
embodiment of the present invention.
[0680] Besides the IP packet or the MPEG-2 TS packet, the packet
used in a general network can be transmitted through the link layer
packet. In this case, the packet type element of the header of the
link layer packet may be set to 111B, and may indicate that the
framed packet is contained in the payload of the link layer
packet.
[0681] FIG. 60 shows a syntax of the framed packet according to an
embodiment of the present invention.
[0682] The syntax of framed packet may include ethernet_type,
length, and/or packet( ).
[0683] The ethernet_type which is a 16-bit field shall identify the
type of packet in the packet( ) field according to the IANA
registry. Only registered values shall be used.
[0684] The length which is a 16-bit field shall be set to the total
length in bytes of the packet( ) structure.
[0685] The packet( ) which is variable length field shall contain a
network packet.
[0686] FIG. 61 is a block diagram illustrating a receiver of the
next generation broadcast system according to an embodiment of the
present invention.
[0687] Referring to FIG. 61, the receiver according to an
embodiment of the present invention may include a receiver (not
shown), a Channel Synchronizer 32010, a Channel Equalizer 32020, a
Channel Decoder 32030, a Signaling Decoder 32040, a Baseband
Operation Controller 32050, a Service Map DB 32060, a Transport
Packet Interface 32070, a Broadband Packet Interface 32080, a
Common Protocol Stack 32090, a Service Signaling Channel Processing
Buffer & Parser 32100, an A/V Processor 32110, a Service Guide
Processor 32120, an Application Processor 32130, and/or a Service
Guide DB 32140.
[0688] The receiver (not shown) may receive broadcast signals.
[0689] The channel synchronizer 32010 may synchronize a symbol
frequency with timing in a manner that signals received at baseband
can be decoded. In this case, the baseband may indicate a Tx/Rx
region of the broadcast signal.
[0690] The channel equalizer 32020 may perform channel equalization
of the received (Rx) signal. The channel equalizer 32020 may
compensate for signal distortion encountered when the Rx signals
are distorted by multipath, Doppler effect, etc.
[0691] The Channel Decoder 32030 may recover the received (Rx)
signal into a meaningful transport frame. The channel decoder 32030
may perform forward error correction (FEC) of data or transport
frame contained in the Rx signal.
[0692] The signaling decoder 32040 may extract and decode signaling
data contained in the received (Rx) signal. Here, the signaling
data may include signaling data and/or service information (SI) to
be described later.
[0693] The baseband operation controller 32050 may control baseband
signal processing.
[0694] The Service Map DB 32060 may store signaling data and/or
service information. The service Map DB 32060 may store signaling
data contained/transmitted in the broadcast signal and/or signaling
data contained/transmitted in the broadband packet.
[0695] The transport packet interface 32070 may extract the
transport packet from the transmission (Tx) frame or the broadcast
signal. The transport packet interface 32070 may extract the
signaling data or the IP datagram from the transport packet.
[0696] The broadband packet interface 32080 may receive
broadcast-related packets through the Internet. The broadband
packet interface 32080 may extract a packet obtained through the
Internet, and combine or extract the signaling data or A/V data
from the corresponding packet.
[0697] The common protocol stack 32090 may process the received
packet according to the protocol contained in the protocol stack.
For example, the common protocol stack 32090 may perform processing
for each protocol, such that it can process the received
packet.
[0698] The service signaling channel processing buffer & parser
32100 may extract signaling data contained in the received packet.
The service signaling channel processing buffer & parser 32100
may scan services and/or contents from the IP datagram or the like,
and may extract signaling information related to acquisition of the
services and/or contents, and parse the extracted signaling
information. The signaling data may be located at a predetermined
position or channel within the received packet. This position or
channel may be referred to as a service signaling channel. For
example, the service signaling channel may have a specific IP
address, a UDP Port number, a transmission session ID, etc. The
receiver may recognize data being transmitted as the specific IP
address, the UDP port number, and the transmission session, etc. as
signaling data.
[0699] The A/V Processor 32110 may perform decoding of the received
audio and video data, and presentation processing thereof.
[0700] The service guide processor 32120 may extract announcement
information from the Rx signal, may manage the service guide DB
32140, and provide the service guide.
[0701] The application processor 32130 may extract application data
contained in the received packet and/or application-associated
information, and may process the extracted data or information.
[0702] The service guide DB 32140 may store the service guide data
therein.
[0703] FIG. 62 is a conceptual diagram illustrating a general
format of a section table according to an embodiment of the present
invention.
[0704] Referring to FIG. 62, the section table according to an
embodiment may include a table_id field, a section_syntax_indicator
field, a section_length field, a version_number field, a
current_next_indicator field, a section_number field, a
last_section_number field, and/or a section data field.
[0705] The table_id field may indicate a unique ID value of the
corresponding table.
[0706] The section_syntax_indicator field may indicate a format of
a table section located behind the corresponding field. If the
corresponding field is set to zero (0), the corresponding table
section indicates a short format. If the corresponding field is set
to 1, the corresponding table section has a general long format.
The corresponding field value according to an embodiment of the
present invention may always be set to 1.
[0707] The section_length field may indicate the length of the
corresponding section, such that it can indicate the length from
the next part of the corresponding field to the last part of the
corresponding section in bytes.
[0708] The version_number field may indicate a version of the
corresponding table.
[0709] If the current_next_indicator field is set to 1, this means
that the corresponding section table is valid. If the
current_next_indicator field is set to 0, this means that the next
section table to be subsequently transmitted is valid.
[0710] The section_number field may indicate the number of sections
contained in the corresponding table. If the first section
constructing the corresponding table is decided, the section_number
field value may indicate zero, and may also be sequentially
increased.
[0711] The last_section_number field may indicate the number of the
last section from among a plurality of sections constructing the
corresponding table.
[0712] The section data field may include data contained in the
corresponding section.
[0713] The field denoted by "Special Use" may be a field that can
be differently configured according to individual tables. The
number of bits allocated to "Special Use" may be maintained without
change.
[0714] FIG. 63 is a conceptual diagram illustrating a link layer
packet for transmitting signaling information according to an
embodiment of the present invention.
[0715] If signaling information is transmitted using the link layer
packet, the value of the packet type element may be set to
`110B`.
[0716] FIG. 63 shows a header structure of the link layer packet
when signaling information is transmitted. Referring to FIG. 63,
during transmission of the signaling information, a signaling type
field of 2 bits may be located behind the packet type element. The
signaling type field may indicate a format of the signaling
information to be transmitted. The remaining 3-bit part of the
fixed header subsequent to the signaling type field and the
extended header may be decided.
[0717] If the signaling type field according to an embodiment
denotes `00B`, this means that the signaling type is a section
table. In case of the section table, information regarding section
separation and the section length information are contained in the
field of the table, such that the link layer packet may indicate
only the packet type and the signaling type without additional
processing, and then transmit the packet type and the signaling
type. If the signaling type has a section table format, the
remaining 3 bits other than the packet type element and the
signaling type field of the fixed header part are not in use, and
may be reserved for a subsequent use. If the signaling type has a
section table format, the extended header is not used. If there is
a need to indicate the length of the link layer packet, the
extended header of 1 or 2 bytes may be added and may be used as a
length field.
[0718] If the signaling type field according to the embodiment
denotes `01B`, this means that the signaling type has a descriptor
format. Generally, the descriptor is used as some parts of the
section table. If only the descriptor needs to be transmitted
through simple signaling, the descriptor may be transmitted as the
corresponding signaling type. The descriptor may be shorter in
length than the section table, so that several descriptors may be
contained in one link layer packet and then transmitted. 3 bits
corresponding to the indicator part of the fixed header according
to the embodiment may be used to indicate how many descriptors are
contained in one link layer packet. If the signaling type is a
descriptor format and the extended header is not in use, the length
of the link layer packet can be displayed using the corresponding
descriptor length information contained in the descriptor without
using the extended header. If it is necessary to separately display
the link layer packet length, the extended header of 1 or 2 bytes
is added, and may be used as the length field.
[0719] The signaling type field value (10B) according to an
embodiment may be reserved to support other kinds of signaling.
[0720] If the signaling type field according to the embodiment
indicates the value of 11B, this means that the signaling type is
GSE-LLC. The GSE-LLC signaling may be segmented as necessary.
Therefore, if the signaling type is GSE-LLC, the remaining 3 bits
other than the packet type element and the signaling type field of
the fixed header part may be used as the segment ID. If the
signaling type is GSE-LLC, the extended header of 2 bytes may be
added, and may also be composed of Seg_SN (Segment Sequence Number)
of 4 bits and the length field of 12 bits.
[0721] GSE-LLC according to an embodiment is an abbreviation of
Generic Stream Encapsulation Logical Link Control, and may indicate
one of two affiliated layers of the data link layer of the OSI
model.
[0722] FIG. 64 shows the meaning of values denoted by the signaling
type field, and contents of a fixed header and an extended header
located behind the signaling type field.
[0723] If the signaling type field according to an embodiment
indicates `00B`, the field subsequent to the signaling type field
may not be present.
[0724] If the signaling type field according to an embodiment
indicates `01B`, the Concatenation Count (Count) field may be
located behind the signaling type field. The Concatenation Count
(Count) field may be present only when the descriptor instead of
the section table is transmitted as signaling information. The
Concatenation Count (Count) field may indicate how many descriptors
are contained in payload of the link layer packet. A detailed
description of the Concatenation Count (Count) will hereinafter be
disclosed.
[0725] If the signaling type field according to an embodiment
indicates `11B`, the Seg_ID (Segment ID) field, the Seg_SN (Segment
Sequence Number) field, and/or the length field may be located
subsequent to the signaling type field. In case of LLC signaling
data capable of being transmitted using DVB_GSE, the LLC signaling
data may be autonomously segmented. When LLC data is segmented, the
Seg_ID (Segment ID) field may indicate an ID for identifying the
segmented data. If segments of the transmitted LLC data are
integrated into one, the receiver may recognize that the segments
of individual LLC data pieces are constituent elements of the same
LLC data using the Seg_ID (Segment ID) field. The Seg_ID (Segment
ID) field is 3 bits long, and may identify 8 segments (or 8
segmentations). If the Seg_SN (Segment Sequence Number) field is
segmented, it may also indicate the order of respective segments.
Since the index of the corresponding data table is contained in the
front part of LLC data, individual segments generated when the
receiver receives the packet must be sequentially aligned at all
times. Although the link layer packets having payload segmented
from one LLC data have the same Seg_ID, the link layer packets may
have different segment sequence numbers (Seg_SN), and may be 4
longs long. One LLC data may be divided into a maximum of 16
segments. The length field may indicate the length of LLC data
corresponding to the payload of the current link layer packet in
bytes. Accordingly, a total length of the link layer packet may be
denoted by "header length (3 bytes)+Value denoted by the length
field".
[0726] DVB_GSE is an abbreviation of DVB-Genneric Stream
Encapsulation, and may indicate the data link layer protocol
defined by DVB.
[0727] FIG. 65 shows the number of descriptors contained in payload
of the link layer packet according to a concatenation count field
value according to an embodiment of the present invention.
[0728] As many descriptors as the number of specific numerals each
being denoted by "Concatenation Count (Count) field value+1" may
construct payload of a single link layer packet. Accordingly, since
the number of bits allocated to the Concatenation Count (Count)
field is 3, a maximum of 8 descriptors may be composed of one link
layer packet.
[0729] FIG. 66 is a conceptual diagram illustrating a process for
encapsulating the section table into payload when signaling
information input to the payload of the link layer packet is a
section table.
[0730] In accordance with one embodiment of the present invention,
one section table may be used as the payload of the link layer
packet without change. In this case, a value indicated by the
packet type element may be 110B (signaling), and a value indicated
by the signaling type field may be 00B (section table). The
remaining 3 bits other than the packet type element and the
signaling type field of the fixed header may be reserved for
subsequent use.
[0731] The field contained in the section table according to an
embodiment may include a field indicating the length of the
corresponding section. The field indicating the length of the
corresponding section may always be located at the same position,
and the field shifted from the beginning of the payload of the link
layer packet by a predetermined offset is confirmed, so that the
payload length can be confirmed. In case of the section table, the
section length (section length) field of 12 bits may be present at
a specific position corresponding to movement of 12 bits on the
basis of the beginning part of payload. The section_length_field
may indicate the length from a part subsequent to the
section_length_field to the last part of the section. Therefore, a
specific part not contained in the section length field and the
header length of the link layer packet are added to a specific
value indicated by the section length field, so that the length of
a total link layer packet can be derived. In this case, the part (3
bytes) not contained in the section length field may include a
length of the table ID field (table_id_field) and a length of the
section length field (section_length_field) of the section table.
The header length of the link layer packet may be 1 byte long. That
is, the total length of the link layer packet may be identical to
"4 bytes+Value denoted by the section length field".
[0732] If the receiver according to the embodiment receives the
link layer packet including the section table, the receiver may
obtain/use information regarding the corresponding section table
through the table ID field (table_id field) of 8 bits located
subsequent to the fixed header of the link layer packet.
[0733] FIG. 67 is a conceptual diagram illustrating a syntax of a
network information table (NIT) according to an embodiment of the
present invention.
[0734] In accordance with the embodiment of the present invention,
if the section table for signaling is contained in payload of the
link layer packet and the resultant section able is transmitted, a
network information table indicating information related to the
current broadcast network may be contained as the section table in
the payload of the link layer packet.
[0735] The network information table according to the embodiment
may include a table_id field, a section_syntax_indicator field, a
section_length field, a network_id field, a version_number field, a
current_next_indicator field, a section_number field, a
last_section_number field, a network_descriptors_length field, a
descriptor( ) field, a transport_stream_loop_length field, a
broadcast_id field, an original_network_id field, a
delivery_system_descriptor_length field, and/or a
delivery_system_descriptor( ) field.
[0736] From among a plurality of fields contained in the network
information table according to the embodiment, some fields having
the same titles as the fields described in the drawing showing a
general format of the above-mentioned section table may be replaced
with the above-mentioned description.
[0737] The network_id field may indicate a unique ID of the
broadcast network being currently used.
[0738] The network_descriptors_length field may indicate the length
of descriptor indicating the network associated information at the
network level.
[0739] The descriptor( ) may indicate a descriptor showing the
network associated information at a network level.
[0740] The transport_stream_loop_length field may indicate the
length of stream associated information that is transmitted on the
broadcast network.
[0741] The broadcast_id field may indicate a unique ID of a
broadcast station existing in the broadcast network.
[0742] The original_network_id field may indicate a unique ID of
the broadcast network having been originally used. If the
originally used broadcast network is different from the current
broadcast network, NIT may include information regarding the
broadcast network that has been originally used through the
original_network_id field.
[0743] The delivery_system_descriptor_length field may indicate the
length of the descriptor indicating detailed information related to
the delivery system (delivery_system) on the current broadcast
network.
[0744] The delivery_system_descriptor( ) may indicate a descriptor
including detailed information associated with the delivery system
(delivery_system) on the current broadcast network.
[0745] FIG. 68 is a conceptual diagram illustrating a syntax of a
delivery system descriptor contained in a network information table
(NIT) according to an embodiment of the present invention.
[0746] Referring to FIG. 68, the delivery system descriptor
according to the embodiment may include information of Physical
Layer Pipe (PLP) configured to transmit signaling data related to
data transferred from a specific broadcast station on the transmit
(Tx) system.
[0747] The delivery system descriptor may include a descriptor_tag
field, a descriptor_length field, a delivery_system_id field, a
base_PLP_id field, a base_PLP_version field, and/or a
delivery_system_parameters( ) field.
[0748] The descriptor tag field may indicate an identifier for
indicating that the corresponding descriptor is a delivery system
descriptor.
[0749] The descriptor_length field may indicate the length of the
corresponding descriptor.
[0750] The delivery_system_id field may indicate a unique delivery
system ID of the broadcast network.
[0751] The base_PLP_id field may indicate a representative PLP
(Physical Layer Pipe) for decoding components of the broadcast
service transmitted from a specific broadcast station identified by
`broadcast_id`. In this case, PLP may indicate a data pipe of a
physical layer, and may include PSI/SI information or the like in a
broadcast service transmitted from a specific broadcast
station.
[0752] The base_PLP_version field may indicate version information
according to variation of data transmitted through PLP identified
by `base_PLP_id`. For example, if service signaling such as PSI/SI
is transferred through base_PLP, the base_PLP_version field value
may be increased by one whenever the service signaling is
changed.
[0753] The delivery system_parameters( ) field may include
parameters for indicating characteristics of the broadcast delivery
system. The parameters may include a bandwidth, a guard interval, a
transmission mode, a center frequency, etc.
[0754] FIG. 69 is a conceptual diagram illustrating a syntax of a
fast information table (FTT) according to an embodiment of the
present invention.
[0755] In accordance with one embodiment, if the section table for
signaling is contained in payload of the link layer packet and is
then transmitted, a fast information table (FIT) may be contained
as a section table in the payload of the link layer packet. The
receiver according to an embodiment may quickly and easily scan and
obtain the broadcast service through the fast information table
(FIT).
[0756] The fast information table (FIT) may include a table_id
field, a private indicator field, a section_length field, a
table_id_extension field, a FIT_data_version field, a
current_next_indicator field, a section_number field, a
last_section_number field, a num_broadcast field, a broadcast_id
field, a delivery_system_id field, a base_PLP_id field, a
base_PLP_version field, a num_service field, a service_id field, a
service_category field, a service_hidden_flag field, an
SP_indicator field, a num_component field, a component_id field,
and/or a PLP id field.
[0757] From among a plurality of fields contained in the fast
information table (FIT) according to the embodiment, some fields
having the same titles as the fields described in the drawing
showing a general format of the above-mentioned section table may
be replaced with the above-mentioned description.
[0758] The table_id field may indicate that the corresponding table
includes information related to quick scanning of the service and
the corresponding table corresponds to the fast information table
(FIT).
[0759] The private_indicator field may always be set to 1.
[0760] The table_id_extension field may correspond to some parts of
the table_id field, and provide a scope for the remaining
fields.
[0761] The FIT_data_version field may indicate version information
of the syntax and semantics contained in the fast information table
(FIT). The receiver according to the embodiment may decide whether
signaling information contained in the corresponding table is
processed using the FIT_data_version field.
[0762] The num_broadcast field may indicate the number of broadcast
stations configured to transmit a broadcast service or content
through a frequency or a transmitted transport frame.
[0763] The broadcast_id field may indicate a unique ID of the
broadcast station configured to transmit a broadcast service or
content through a field frequency or a transmitted transport frame.
In case of the broadcast station configured to transmit MPEG-2 TS
based data, the broadcast_id field may include the same value as in
`transport_stream_id" of MPEG-2 TS.
[0764] The delivery_system_id field may indicate an identifier of
the broadcast delivery system configured to use the same transmit
parameter on the broadcast network.
[0765] The base_PLP_id field may indicate an identifier of PLP
configured to transmit the broadcast service signaling information
transferred from a specific broadcast station identified by
`broadcast_id`. The base_PLP_id field may indicate a representative
PLP for decoding components of the broadcast service transmitted
from a specific broadcast station identified by `broadcast_id`. In
this case, PLP may indicate a data pipe of the physical layer, and
may include PSI/SI information in the broadcast service transferred
from a specific broadcast station.
[0766] The base_PLP_version field may indicate version information
according to variation of data transmitted through PLP identified
by `base_PLP_id`. For example, if service signaling information
such as PSI/SI is transferred through `base_PLP`, the
base_PLP_version field value may be increased by one whenever the
service signaling information is changed.
[0767] The num_service field may indicate the number of broadcast
services transferred from a broadcast station identified by
`broadcast_id` within the corresponding frequency or a transport
frame.
[0768] The service_id field may indicate an ID for identifying the
broadcast service.
[0769] The service_category field may indicate a category of the
broadcast service. For example, if the service_category field value
is 0x01, this means Basic TV. If the service_category field value
is 0x02, this means Basic Radio. If the service_category field
value is 0x03, this means RI service. If the service_category field
value is 0x08, this means Sevice Guide. If the service_category
field value is 0x09, this means Emergency Alerting.
[0770] The service_hidden_flag field may indicate whether the
corresponding broadcast service is hidden or not. If the
corresponding broadcast service is hidden, the corresponding
service may correspond to a test service or a service being
autonomously used, so that the receiver according to the embodiment
may disregard the above-mentioned hidden broadcast service or may
allow the hidden broadcast service to be hidden from the service
list.
[0771] The SP_indicator field may indicate whether service
protection is applied to one or more components of the
corresponding broadcast service.
[0772] The num_component field may indicate the number of
components contained in the corresponding broadcast service.
[0773] The component_id field may indicate an ID for identifying
the corresponding component of the broadcast service.
[0774] The PLP_id field may indicate an identifier for identifying
PLP through which the corresponding component is transmitted within
the broadcast service.
[0775] FIG. 70 is a conceptual diagram illustrating a process for
encapsulating a descriptor into payload when signaling information
input to payload of the link layer packet is a descriptor.
[0776] In accordance with one embodiment, one or more descriptors
may be contained in the payload of the link layer packet. In this
case, a value indicated by the packet type element is set to 110B
(signaling), and a value indicated by the signaling type field may
be set to 01B (descriptor). In FIG. 70, the remaining 3 bits other
than the packet type element and the signaling type field of the
fixed header may indicate a count field that indicates how many
descriptors are contained in the payload of a single link layer
packet. The payload of the single link layer packet may include a
maximum of 8 descriptors.
[0777] In accordance with one embodiment, all descriptors may
include a descriptor_tag field of 1 byte and a descriptor_length
field of 1 byte in the beginning part of the descriptor. In
accordance with one embodiment, the length of a concatenated packet
can be calculated using the descriptor_length field. The
descriptor_length field is always located at the same position
within the descriptor, such that a field located at a specific
position shifted from the beginning part of the payload of the link
layer packet by a predetermined offset is confirmed and therefore
the payload length can be confirmed. In case of the descriptor, the
descriptor_length field of 8 bits at a specific position shifted
from the beginning part of the payload by 8 bits may be present.
The descriptor_length field may indicate the length from a part
located behind the corresponding field to the last part of the
descriptor. Therefore, "the length (1 byte) of the descriptor tag
field not contained in the descriptor_length field+the length (1
bytes) of the descriptor_length field" are added to a specific
value denoted by the descriptor_length field, so that the length of
one descriptor can be derived. As many descriptor lengths as the
number of descriptors indicated by the count field are added so
that the length of a total link layer packet can be derived. For
example, a second descriptor contained in the payload of the link
layer packet according to an embodiment may start from a specific
position shifted from the beginning part of the payload by the
length of a first descriptor, the descriptor_length field of the
second descriptor is located at a specific position shifted from
the beginning part of the second descriptor by a predetermined
offset, and the descriptor_length field is confirmed, so that the
total length of the second descriptor can be derived. By the
above-mentioned processes, the length of each descriptor contained
in the payload of the link layer packet may be calculated, and the
header length of the link layer packet is added to the sum of the
lengths of individual descriptors, so that a total length of the
link layer packet can be calculated.
[0778] If the receiver receives the link layer packets including
one or more descriptors, the receiver may obtain/use the signaling
information contained in each descriptor through the 8-bit
descriptor_tag field value contained in each descriptor.
[0779] FIG. 71 is a conceptual diagram illustrating a syntax of a
fast information descriptor according to an embodiment of the
present invention.
[0780] In accordance with the embodiment, if the descriptor for
signaling is contained in the payload of the link layer packet and
then transmitted, the fast information descriptor may be contained
in the payload of the link layer packet. The receiver may quickly
and easily scan and obtain the broadcast service through the fast
information descriptor.
[0781] The fast information descriptor according to an embodiment
may include a descriptor_tag field, a descriptor_length field, a
num_broadcast field, a broadcast_id field, a delivery_system_id
field, a base_PLP_id field, a base_PLP_version field, a num_service
field, a service_id field, a service_category field, a
service_hidden_flag field, and/or an SP_indicator field.
[0782] From among a plurality of fields contained in the fast
information descriptor according to the embodiment, some fields
having the same titles as the fields described in the drawing
showing a general format of the above-mentioned section table may
be replaced with the above-mentioned description.
[0783] The descriptor_tag field may indicate a fast information
descriptor indicating that the corresponding descriptor includes
information related to quick service scanning.
[0784] The descriptor_length field may indicate the length of the
corresponding descriptor.
[0785] FIG. 72 is a conceptual diagram illustrating a delivery
system descriptor according to an embodiment of the present
invention.
[0786] In accordance with one embodiment, if the descriptor for
signaling is contained in the payload of the link layer packet and
then transmitted, the delivery system descriptor may be contained
in the payload of the link layer packet. The delivery system
descriptor may include information regarding PLP (Physical Layer
Pipe) configured to transmit signaling data related to data
transferred from a specific broadcast station on the transmit (Tx)
system.
[0787] The delivery system descriptor according to the embodiment
may include a descriptor_tag field, a descriptor_length field, a
delivery_system_id field, a num_broadcast field, a base_PLP_id
field, a base PLP version field, a
delivery_system_parameters_length field, and/or a
delivery_system_parameters( ) field.
[0788] The descriptor_tag may indicate that the corresponding
descriptor is a delivery system descriptor.
[0789] The descriptor_length field may indicate the length of the
corresponding descriptor.
[0790] The delivery_system_id field may indicate an ID for
identifying a delivery system configured to transmit the same
transmit (Tx) parameters on the broadcast network.
[0791] The num_broadcast field may indicate the number of broadcast
stations configured to transmit a broadcast service or content
through a frequency or a transmitted transport frame.
[0792] The base_PLP _id field may indicate a representative PLP
(Physical Layer Pipe) for decoding constituent components of the
broadcast service transferred from a specific broadcast station
identified by `broadcast_id`. In this case, PLP may denote a data
pipe of the physical layer, and may include PSI/SI information in
the broadcast service transferred from a specific broadcast
station.
[0793] The base_PLP _version field may indicate version information
according to variation of data transferred through PLP identified
by base_PLP_id. For example, if service signaling such as PSI/SI is
transferred through base_PLP, the base_PLP_version field value may
be increased by one whenever the service signaling is changed.
[0794] The delivery_system_parameters length field may indicate the
length of delivery_system_parameters( ) subsequent to the
corresponding field.
[0795] The delivery_system_parameters( ) field may include
parameters for indicating characteristics of the broadcast delivery
system. The parameters may include a bandwidth, a guard interval, a
transmission mode, a center frequency, etc.
[0796] The delivery system descriptor according to the embodiment
may be contained in the network information table (NIT) and then
transmitted.
[0797] If the delivery system descriptor is contained in the
network information table (NIT) and then transmitted, a syntax of
the delivery system descriptor has already been disclosed in the
detailed description of the network information table (NIT).
[0798] FIG. 73 is a conceptual diagram illustrating a process for
encapsulating one GSE-LLC datum into payload of one link layer
packet when signaling information input to payload of the link
layer packet has a GSE-LLC format used in DVB-GSE.
[0799] LLC data according to one embodiment may be classified into
an index part and a record part. The record part may also be
classified into a few tables. In this case, the table constructing
the record part may have a GSE table structure, and may also have a
general section table structure.
[0800] In FIG. 73, one LLC datum may be used as payload of a single
link layer packet. In this case, a value indicated by the packet
type element may be 110B (signaling), and a value indicated by the
signaling type field may be 11B (GSE-LLC). If GSE-LLC formatted
signaling information is transferred, the link layer packet may
have an extended header of 2 bytes. The extended header of 2 bytes
may be composed of the Seg_SN (segment sequence number) of 4 bytes
and the length field of 12 bits. The length field may be assigned a
specific value indicating a total length of the link layer packet
according to a system structure, or may also be assigned a value
indicating the payload length of the link layer packet.
[0801] FIG. 74 is a conceptual diagram illustrating a process for
encapsulating one GSE-LLC datum into payload of several link layer
packets when signaling information input to payload of the link
layer packet has a GSE-LLC format used in a DVB-GSE standard.
[0802] If LLC data is segmented, the Seg_ID fields indicating
segmentation from LLC data may have the same value.
[0803] The Seg_SN field may include the order of segments in such a
manner that the receiver according to the embodiment receives and
recombines the segmented LLC data. If one LLC datum is contained in
the payload of the single link layer packet, the Seg_SN field may
be set to zero (0).
[0804] The receiver according to the embodiment may recognize the
number of segments of LLC data related to the corresponding Seg_ID
through the LLC index part.
[0805] FIG. 75 illustrates a header of a link layer packet for
Robust Header Compression (RoHC) transmission according to the
present invention.
[0806] In an Internet Protocol (IP)-based broadcast environment, an
IP packet may be compressed into the above-described link layer
packet and be transmitted. When streaming is performed in an
IP-based broadcast system, information about a header of the IP
packet may be rarely changed and maintained. Based on this fact,
the header of the IP packet may be compressed.
[0807] An RoHC scheme is mainly used to compress the header of the
IP packet (which is also referred to as an IP header). The present
invention proposes a compression (encapsulation) scheme for a case
in which an RoHC packet is input to a link layer.
[0808] When the RoHC packet is input to the link layer, the
above-described packet type element may have a value 010B. The
value indicates that a packet delivered from the higher layer to
the link layer is a compressed IP packet as described above.
[0809] When the RoHC packet is input, the header of the link layer
packet may include a fixed header and/or an extended header
similarly to the other packets described above.
[0810] The fixed header may include a packet type field and/or a
packet configuration (PC) field. The fixed header may have a size
of 1 byte in total. Here, the packet type field corresponds to a
case of the compressed IP packet and thus may have a value of 010.
The extended header may have a size which is fixed or varies
according to a given embodiment.
[0811] The PC field of the fixed header may be a field indicating a
form in which the RoHC header included in a payload of the link
layer packet is processed. The PC field has a value that may
determine information about a remaining portion of the fixed header
and the extended header following the PC field. In addition, the PC
field may contain length information of the extended header based
on the form in which the RoHC header is processed. The PC field may
have a size of 1 bit.
[0812] A case in which the PC field has a value 0B will be
described.
[0813] The case in which the PC field has the value 0B corresponds
to a case in which the payload of the link layer packet includes
one RoHC packet or a concatenation of two or more RoHC packets. The
concatenation indicates that several packets having short lengths
are connected to each other to form the payload of the link layer
packet.
[0814] When the PC field has the value 0B, the PC field may be
followed by a 1-bit common CID indicator (CI) field and a 3-bit
count field. In this way, the extended header may be additionally
provided with common CID information and a length part. The length
part may be a part indicating a length of the RoHC packet.
[0815] The CI field may be set to 1 when RoHC packets included in a
payload of one link layer packet have the same context ID (CID),
and be set to 0 otherwise. When the CI field has a value 1, an
overhead processing scheme for a common CID may be applied. The CI
field may correspond to 1 bit.
[0816] The count field may indicate the number of RoHC packets
included in the payload of the one link layer packet. When a
concatenation of RoHC packets is included, the number of the RoHC
packets may be indicated by the count field. The count field may
correspond to 3 bits. Thus, a maximum of eight RoHC packets may be
included in the payload of the one link layer packet as shown in
Table 34 below. When the count field has a value 000, one RoHC
packet rather than the concatenation of RoHC packets is included in
the payload of the link layer packet.
TABLE-US-00035 TABLE 34 Count (3 bits) No. of Concatenated RoHC
packets 000 1 001 2 010 3 011 4 100 5 101 6 110 7 111 8
[0817] As described in the foregoing, the length part may be a part
indicating a length of the RoHC packet. The RoHC packet has an RoHC
packet header excluding length information. Thus, it is impossible
to use a length field in the RoHC packet header. Therefore, the
header of the link layer packet may include the length part to
enable a receiver to be aware of a length of the RoHC packet.
[0818] When a maximum transmission unit (MTU) is not determined,
the IP packet has a maximum length of 65,535 bytes. Thus, 2-byte
length information is required to support up to a maximum length of
the RoHC packet. When a concatenation of several RoHC packets is
included, length fields corresponding to the number designated in
the count field may be additionally provided. In this case, the
length part may include a plurality of length fields. However, when
one RoHC packet is included in the payload, only one length field
may be included. The length fields may be arranged in an order of
the RoHC packets included in the payload of the link layer packet.
Each of the length fields may have a value in bytes.
[0819] A common CID field may be a field for transmission of the
common CID. The RoHC packet may include a CID for verification of a
relation between compressed headers in a header part. The CID may
retain the same value in a stable link state. Therefore, all the
RoHC packets included in the payload of the one link layer packet
may include the same CID. In this case, to reduce overhead, CIDs
may be removed from header parts of contiguous RoHC packets
included in the payload, and an associated value may be displayed
in the common CID field and be transmitted to the header of the
link layer packet. The receiver may recombine the CIDs of the RoHC
packets using the common CID field. When the common CID field is
present, the above-described CI field has a value of 1.
[0820] A case in which the PC field has a value 1B will be
described.
[0821] The case in which the PC field has the value 1B corresponds
to a case in which the payload of the link layer packet includes a
segmented packet of the RoHC packet. Here, the segmented packet may
correspond to a configuration in which the RoHC packet, which is
long, is divided into a plurality of segments, and one of the
segments is included in the payload of the link layer packet.
[0822] When the PC field has the value 1B, the PC field may be
followed by a 1-bit last segment indicator (LI) field and a 3-bit
segment ID field. In addition, to additionally provide information
about segmentation, a segment sequence number field, a segment
length ID field, a last segment length field, and the like may be
additionally provided to the extended header.
[0823] The LI field is a field used when the RoHC packet is
segmented. The RoHC packet may be divided into a plurality of
segments. When an LI has a value 1, a segment currently included in
the link layer packet may be a last segment corresponding to one of
the segments divided from one RoHC packet. When the LI has a value
0, a segment currently included in the link layer packet may not be
the last segment. The LI field may be used to determine whether all
the segments are received when the receiver collects the segments
to recombine one RoHC packet. The LI field may correspond to 1
bit.
[0824] The segment ID (Seg_ID) field may be a field indicating an
ID assigned to the RoHC packet when the RoHC packet is segmented.
All segments derived from one RoHC packet may have segment IDs
corresponding to the same value. When the receiver combines
respective transmitted segments into one entity, it is possible to
determine whether the segments correspond to elements of the same
RoHC packet using the segment IDs. The segment ID field may
correspond to 3 bits. Therefore, it is possible to simultaneously
support segmentations of eight RoHC packets.
[0825] The segment sequence number (Seg_SN) field may be a field
used to verify an order of respective segments when the RoHC packet
is segmented. That is, link layer packets having segments derived
from one RoHC packet as payloads may have the same Seg_ID and have
different Seg_SNs. Therefore, the one RoHC packet may be divided
into a maximum of 16 segments.
[0826] The segment length ID (Seg_Len_ID) field may be used to
express a length of each of the segments. However, the segment
length ID field may be used to express lengths of a plurality of
segments except for the last segment. The length of the last
segment may be indicated by the last segment length field to be
described below. The segment length ID field may be present when
the payload of the link layer packet does not correspond to the
last segment of the RoHC packet, that is, the LI has a value 0.
[0827] To reduce overhead of the header, a segment may have a
length limited to 16. An input size of a packet may be determined
based on a code rate of forward error correction (FEC) processed in
a physical layer. The segment length may be determined based on the
input size and be designated as a Seg_Len_ID. When the physical
layer operates irrespective of the segment length, the segment
length may be determined as below.
Segment Length=Seg_Len_ID.times.Len_Unit min_Len [bytes] [Math FIG.
12]
[0828] Here, Len_Unit (Length Unit) is a basic unit for expression
of the segment length, and min_Len may refer to a minimum value of
the segment length. A transmitter and a receiver have the same
values of Len_Unit and min_Len. It is efficient for a system
operation when the values do not change after being determined. In
addition, Len_Unit and min_Len may be determined based on an FEC
processing ability of the physical layer in a system initialization
process.
[0829] Table 35 summarizes segment lengths expressed based on
values of Seg-Len_ID. A length assigned to Seg-Len_ID corresponds
to an example and thus the length may be changed according to
intent of a designer. In this example, a Len_Unit value is 256, and
a min_Len value is 512.
TABLE-US-00036 TABLE 35 Seg_Len_ID Segment Length (byte) 0000 512
(=min_Len) 0001 768 0010 1024 0011 1280 0100 1536 0101 1792 0110
2048 0111 2304 1000 2560 1001 2816 1010 3072 1011 3328 1100 3584
1101 3840 1110 4096 1111 4352
[0830] The last segment length (L_Seg_Len) field is a field used
when a segment included in the payload of the link layer packet is
the last segment of the RoHC packet. That is, the last segment
length field is a field used when the LI field has a value 1. The
RoHC packet may be divided equally from the front part using
Seg_Len_ID. In this case, the last segment may not have a size
indicated by Seg_Len_ID. Therefore, the last segment may have a
length directly indicated by the L_Seg_Len field. The L_Seg_Len
field may indicate 1 to 4,095 bytes. This may be changed depending
on an embodiment.
[0831] FIG. 76 illustrates Embodiment #1 of a method of
transmitting an RoHC packet using a link layer packet, according to
the present invention.
[0832] The present embodiment corresponds to a case in which RoHC
packets are within a processing range of a physical layer and thus
one RoHC packet is included in a payload of the link layer packet.
In this case, the RoHC packets are concatenated and may not be
segmented.
[0833] In this case, the one RoHC packet may become the payload of
the link layer packet without change. A packet type may have a
value 010B, a PC field may have a value 0B, and a CI field may have
a value 0B. The above-described count field may have a value 000B
as described in the foregoing since the one RoHC packet forms the
(one) payload without change. The count field may be followed by a
2-byte length field indicating a length of an RoHC packet. Only one
packet is included in the payload and thus a length part may
include only one length field.
[0834] In the present embodiment, a link layer header corresponding
to 3 bytes in total may be additionally provided. Therefore, when
the RoHC packet has a length of L bytes indicated by the length
field, the link layer packet has a length of L+3 bytes in
total.
[0835] FIG. 77 illustrates Embodiment #2 of a method of
transmitting an RoHC packet using a link layer packet, according to
the present invention.
[0836] The present embodiment corresponds to a case in which RoHC
packets are out of a processing range of a physical layer and thus
a plurality of RoHC packets are concatenated and included in a
payload of the link layer packet.
[0837] In this case, a PC field and a CI field have values
corresponding to a case in which one RoHC packet is included in the
payload. The PC field and the CI field are followed by a count
field. As described in the foregoing, the count field may have a
value in a range of 001B to 111B depending on the number of RoHC
packets included in the payload.
[0838] Thereafter, 2-byte length fields corresponding to the number
indicated by the count field may be positioned. Each of the length
fields may indicate a length of each of the RoHC packets. The
length fields may be referred to as a length part.
[0839] Here, when the number indicated by the count field is n,
RoHC packets R1, R2, . . . , and Rn having lengths L1, L2, . . . ,
and Ln, respectively, may be concatenated in the payload of the
link layer packet.
[0840] An extended header may have a length of 2n bytes in total. A
total length LT of the link layer packet may be expressed by the
following Equation.
L T = 1 + 2 n + k = 1 n L k [ bytes ] [ Math Figure 13 ]
##EQU00008##
[0841] FIG. 78 illustrates Embodiment #3 of a method of
transmitting an RoHC packet using a link layer packet, according to
the present invention.
[0842] The present embodiment corresponds to a case in which a
plurality of RoHC packets are connected to each other
(concatenated) to form a payload of the link layer packet, and the
concatenated RoHC packets have the same CID.
[0843] When the RoHC packets have the same CID, and a CID is
indicated and transmitted once, a receiver may restore the RoHC
packets and headers of the RoHC packets. Therefore, a CID common to
the RoHC packets may be extracted and transmitted once. In this
instance, overhead may be reduced.
[0844] In this case, the above-described CI field has a value 1,
which indicates that the same CID is processed. The RoHC packets
having the same CID are indicated by [R1, R2, R3, . . . , Rn]. The
CID common to the RoHC packets may be referred to as a common CID.
A packet corresponding to an RoHC packet excluding a CID from a
header is indicated by R'k (k is 1, 2, . . . , or n).
[0845] The payload of the link layer packet may include R'k (k is
1, 2, . . . , or n). A common CID field may be additionally
provided to a tail of an extended header of the link layer packet.
The common CID field may be a field for transmission of the common
CID. The common CID field may be transmitted as a portion of the
extended header or as a portion of the payload of the link layer
packet. Depending on a system operation, the common CID field may
be appropriately rearranged at a portion for verification of a
position.
[0846] The common CID field may have a size varying according to a
configuration of the RoHC packet.
[0847] When the configuration of the RoHC packet corresponds to a
small CID configuration, the RoHC packet may have a CID size of 4
bits. When rearrangement is performed by extracting a CID from the
RoHC packet, the entire add-CID octet may be processed. That is,
the common CID field may have a length of 1 byte. Alternatively,
after extracting a 1-byte add-CID octet from the RoHC packet, only
a 4-bit CID may be assigned to the common CID field, and the
remaining 4-bit CID may be reserved to be used later.
[0848] When the configuration of the RoHC packet corresponds to a
large CID configuration, the RoHC packet may have a CID size of 1
byte or 2 bytes. The CID size is determined in an RoHC
initialization process. Depending on the CID size, the common CID
field may have a length of 1 byte or 2 bytes.
[0849] In the present embodiment, the payload of the link layer
packet may have a length calculated as below. Lengths of n RoHC
packets R1, R2, . . . , and Rn having the same CID may be referred
to as L1, L2, . . . , and Ln, respectively. When the header of the
link layer packet has a length LH, the common CID field has a
length LCID, and the link layer packet has an entire length LT, LH
is as below.
L.sub.H=1+2n+L.sub.CID bytes [Math FIG. 14]
[0850] In addition, LT may be calculated as below.
L T = L H + k = 1 n ( L k - L CID ) bytes [ Math Figure 15 ]
##EQU00009##
[0851] As described in the foregoing, LCID may be determined based
on a CID configuration of the RoHC packet. That is, LCID may be 1
byte for the small CID configuration, and may be 1 byte or 2 bytes
for the large CID configuration.
[0852] FIG. 79 illustrates Embodiment #4 of a method of
transmitting an RoHC packet using a link layer packet, according to
the present invention.
[0853] The present embodiment corresponds to a case in which
respective divided segments are compressed (encapsulated) into a
payload of a link layer packet when an input RoHC packet is out of
a processing range of a physical layer.
[0854] A PC field has a value 1B to report that the payload of the
link layer packet includes a divided RoHC packet. An LI field has a
value 1B only when a segment corresponding to a last portion of the
RoHC packet is included as the payload, and has a value 0B for all
the other segments. The LI field value reports information about an
extended header of the link layer packet. That is, an extended
header having a length of 1 byte may be additionally provided when
the LI field has a value 0B, and an extended header having a length
of 2 bytes may be additionally provided when the LI field has a
value 1B.
[0855] All Seg_IDs have the same value to indicate segments divided
from the same RoHC packet. Successively increasing Seg_SN values
may be recorded in a header to indicate order information of
segments for normal recombination of the RoHC packet in a
receiver.
[0856] When the RoHC packet is divided, segmentation may be
performed by determining lengths of segments as described above. A
value of a Seg_Len_ID matching a length may be recorded in the
header. As described in the foregoing, a length of a last segment
may be directly recorded in an L_Seg_Len field having 12 bits.
[0857] Length information indicated using the Seg_Len_ID and the
L_Seg_Len field may indicate only information about a segment, that
is, the payload of the link layer packet. Therefore, length
information of the entire link layer packet may be obtained by
adding a header length of the link layer packet which may be
obtained using the LI field.
[0858] In a process of recombining the segments of the RoHC packet
at a receiving side, integrity of the recombined RoHC packet needs
to be verified. To this end, cyclical redundancy check (CRC) may be
additionally provided at a tail of an IP packet in a segmentation
process. In general, CRC is additionally provided in a last part of
the RoHC packet and thus CRC may be included in the last segment
after the segmentation process.
[0859] FIG. 80 illustrates a header of a link layer packet for RoHC
transmission according to an embodiment of the present invention
when an MTU is 1,500.
[0860] In general, an RoHC scheme may be applied during video and
audio streaming. In this instance, an MTU of an IP packet may be
set to 1,500 bytes, which indicates that an RoHC packet has a
length less than 1,500 bytes.
[0861] As described in the foregoing, a PC field of a fixed header
may be a field that indicates a form in which an RoHC packet
included in a payload of the link layer packet is processed.
Information about a remaining portion of the fixed header and an
extended header following the PC field may be determined based on a
value of the PC field. In addition, the PC field may include length
information of the extended header based on the form in which the
RoHC packet is processed. The PC field may have a size of 1
bit.
[0862] A case in which the PC field has a value 0B will be
described.
[0863] The case in which the PC field has the value 0B corresponds
to a case in which the payload of the link layer packet includes
one RoHC packet or segmented packets of the RoHC packet. The PC
field may be followed by an SI field. The SI field may indicate
whether the payload of the link layer packet includes one RoHC
packet or segments of the RoHC packet. The fixed header and the
extended header may have fields determined based on a value of the
SI field.
[0864] As described in the foregoing, the SI field may be a field
which indicates whether the payload of the link layer packet
includes one RoHC packet or segments of the RoHC packet. The SI
field having a value 0 may indicate that the payload of the link
layer packet includes one RoHC packet, and the SI field having a
value 1 may indicate that the payload of the link layer packet
includes segments of the RoHC packet. The SI field may correspond
to 1 byte.
[0865] A Seg_ID field may be a field which indicates an ID assigned
to the RoHC packet when the RoHC packet is segmented. This field is
the same as the Seg_ID field described above.
[0866] A Seg_SN field may be a field used to verify an order of
respective segments when the RoHC packet is segmented. This field
is the same as the Seg_SN field described above.
[0867] An LI field may be a field which indicates whether a segment
included in a current link layer packet is a last segment among
segments divided from the RoHC packet when the RoHC packet is
segmented. This field is the same as the LI field.
[0868] A Seg_Len_ID field may be used to express lengths of
respective segments. This field is the same as the Seg_Len_ID field
described above. However, unlink the case described above, the
segments may restrictively have 8 lengths rather than 16 lengths.
In this case, lengths of the segments expressed based on values of
Seg_Len_ID may be summarized as Table 36 below. A length assigned
to Seg_Len_ID is merely an example, and may be changed according to
intent of a designer. In the present embodiment, a Len_Unit value
is 64, and a min_Len value is 256.
TABLE-US-00037 TABLE 36 Seg_Len_ID Segment Length (byte) 000 256
(=min_Len) 001 320 010 384 011 448 100 512 101 576 110 640 111
704
[0869] An L_Seg_Len field may be used to express a length of the
last segment. This field is the same as the L_Seg_Len field
described above. However, unlink the case described above, the
L_Seg_Len field may indicate 1 to 2,048 bytes. This may be changed
according to an embodiment.
[0870] A case in which the PC field has a value 1B will be
described.
[0871] The case in which the PC field has the value 1B corresponds
to a case in which the payload of the link layer packet includes a
concatenation of two or more RoHC packets. The PC field may be
followed by a 1-bit CI field and a 3-bit count field. In this way,
the extended header may be additionally provided with common CID
information and a length part.
[0872] The CI field is a field which indicates whether RoHC packets
included in a payload of one link layer packet have the same CID.
The CI field is as described above.
[0873] The count field may indicate the number of RoHC packets
included in the payload of the one link layer packet. Unlike the
count field described above, a value 000 is assigned to indicate a
concatenation of two RoHC packets. When the count field has a value
111, a concatenation of nine of more RoHC packets may be indicated.
Count field values are summarized as the following Table 37.
TABLE-US-00038 TABLE 37 No. of Concatenated RoHC packets Count (3
bits) (MTU = 1500 bytes) 000 2 001 3 010 4 011 5 100 6 101 7 110 8
111 9 or more packets, Extended length field is used
[0874] The length part may be a part for indication of a length of
the RoHC packet. The length part may include a plurality of length
fields as described above. Each of the length fields may indicate a
length of each RoHC packet.
[0875] In the present embodiment, an MTU corresponds to 1,500 bytes
and thus 11 bits corresponding to a minimum bit for indication of
the MTU may be assigned to a length field. Since 11 bits may
indicate up to 2,048 bytes, a scheme proposed in the present
invention may be used even when the MTU is extended up to 2,048
bytes as necessary. The length field may directly indicate a
length, and indicate the length by mapping the length to a separate
value. As described in the foregoing, length fields corresponding
to the number designated in the count field may be additionally
provided.
[0876] An extended length part may be used to indicate a length of
a ninth RoHC packet or an RoHC packet after the ninth RoHC packet
when nine of more RoHC packets are concatenated. That is, the
extended length part may be used when the count field has a value
111B. The extended length part may include an 11-bit length field
and a 1-bit X field. The two fields may be alternately
positioned.
[0877] A common CID field may be a field for transmission of a
common CID. This field may be the same as the common CID field
described above.
[0878] FIG. 81 illustrates Embodiment #1 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500 according to the present invention.
[0879] The present embodiment may correspond to a case in which a
PC field has a value 1 and a count field has a value other than
111B when the MTU is 1,500.
[0880] In this case, a length part may have length fields
corresponding to the number designated by a count field value as
described above. Since one length field corresponds to 11 bits, a
padding bit may be additionally provided depending on the number of
the length fields. That is, when the number designated by the count
field is set to k, and a size of the one length field is set to s
(bits), a length LLP of the entire length part may be calculated as
below.
L LP = k .times. s 8 [ Bytes ] [ Math Figure 16 ] ##EQU00010##
[0881] In addition, a size of the padding bit additionally provided
to the length part may be calculated as below.
L.sub.padding=(8.times.L.sub.LP)-(k.times.s)[Bits] [Math FIG.
17]
[0882] As described in the foregoing, the length s of the length
field may be 11 bits, which may be used to summarize the sizes of
the length part and the padding bit as below.
TABLE-US-00039 TABLE 38 No. of Concatenated Size of Size of RoHC
packets Length Part Padding Count (3 bits) (MTU = 1500 bytes)
(Bytes) (bits) 000 2 3 2 001 3 5 7 010 4 6 4 011 5 7 1 100 6 9 6
101 7 10 3 110 8 11 1
[0883] FIG. 82 illustrates Embodiment #2 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500 according to the present invention.
[0884] The present embodiment may correspond to a case in which a
PC field has a value 1 and a count field has a value 111B when the
MTU is 1,500. In this case, an extended length part may be
additionally provided as described above.
[0885] A length part positioned in front of the extended length
part includes eight 11-bit length fields and thus may have a length
of 11 bytes in total. Since the count field has the value 111, the
extended length part needs to include at least one length
field.
[0886] As described in the foregoing, the extended length part may
include an 11-bit length field and a 1-bit X field. The two fields
may be alternately positioned. The length field of the extended
length part may be operated similarly to the length fields of the
length part.
[0887] The X field may be a field which indicates whether the X
field is additionally followed by a length field. When the X field
has a value 0, no length field may be additionally provided. When
the X field has a value 1, the X field may be followed by at least
one length field and an X field. Therefore, the extended length
part may continuously increase until the X field has the value 0.
RoHC packets equal in number to X fields may be additionally
positioned in a payload.
[0888] When the number of X fields having the value 1 is set to m
and a size of one length field is set to s (bits) in the extended
length part, a length LELP of the extended length part may be
calculated as below.
L ELP = ( m + 1 ) .times. ( s + 1 ) 8 [ Bytes ] [ Math Figure 18 ]
##EQU00011##
[0889] The extended length part may also have a padding bit for
processing in bytes. The padding bit additionally provided in the
extended length part may have a size calculated as below.
L.sub.E_padding=(8.times.L.sub.ELP)-((m+1).times.(s+1))[Bits] [Math
FIG. 19]
[0890] A padding bit of 4 bits may be additionally provided when
the number of length fields is an odd number, and no padding bit
may be additionally provided when the number of length fields is an
even number.
[0891] FIG. 83 illustrates Embodiment #3 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500 according to the present invention.
[0892] The present embodiment may correspond to a case in which
RoHC packets are within a processing range of a physical layer and
thus one RoHC packet is included in a payload of the link layer
packet.
[0893] In this case, the one RoHC packet may be the payload of the
link layer packet without change. A packet type may have a value
010B, a PC field may have a value 0B, and an SI field may have a
value 0B. The above-described length part may follow the PC and SI
fields. Here, the length part may have one length field. The length
field may correspond to 11 bits. 3 bits of a fixed header and 1
byte of an extended header may be used for the one 11-bit length
field.
[0894] In this case, a link layer header having 2 bytes in total is
additionally provided. Therefore, when the RoHC packet indicated by
the length field has a length of L bytes, the link layer packet has
a total length of L+2 bytes.
[0895] FIG. 84 illustrates Embodiment #4 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500 according to the present invention.
[0896] The present embodiment may correspond to a case in which
respective divided segments are compressed (encapsulated) into a
payload of the link layer packet when the MTU is 1,500 and an input
RoHC packet is out of a processing range of a physical layer.
[0897] An SI field may have a value 1 to indicate segmentation.
[0898] As described in the foregoing, Seg_IDs have the same value,
and Seg_SNs have successively increasing values. An LI field has a
value 1 for a last segment and has a value 0 otherwise. In
addition, Seg_Len_ID and L_Seg_Len fields may be used to indicate a
length of each segment. A detailed scheme of indicating a length
may be similar to that described above.
[0899] Length information of the entire link layer packet may be
obtained by adding a header length of the link layer packet which
may be obtained using the LI field. In addition, CRC may be
additionally provided to verify integrity in a process of
recombining the segments of the RoHC packet at a receiving side.
The CRC may be additionally provided to the last segment.
[0900] FIG. 85 illustrates Embodiment #5 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500, according to the present invention.
[0901] The present embodiment may correspond to a case in which
RoHC packets are out of a processing range of a physical layer and
thus a plurality of RoHC packets are concatenated and included in a
payload of the link layer packet when the MTU is 1,500.
[0902] The present embodiment may correspond to a case in which
eight or less RoHC packets are concatenated. In this case, an
extended length part may not be needed. A PC field may have a value
1, and a CI field may have a value 0. A count field may have a
value in a range of 000B to 110B as described above.
[0903] Here, when a value indicated by the count field is n, RoHC
packets R1, R2, . . . , and Rn having lengths L1, L2, . . . , and
Ln, respectively, may be concatenated in the payload of the link
layer packet. Each length field may have a length of 11 bits. A
padding bit may be positioned at a tail of the length field as
necessary.
[0904] A length LT of the entire link layer packet is as below.
L T = 1 + L LP + k = 1 n L k [ bytes ] [ Math Figure 20 ]
##EQU00012##
[0905] Here, LLP may denote a length of the entire length part, and
LK may denote a length of each RoHC packet.
[0906] FIG. 86 illustrates Embodiment #6 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500, according to the present invention.
[0907] The present embodiment may correspond to a case in which
RoHC packets are out of a processing range of a physical layer and
thus a plurality of RoHC packets are concatenated and included in a
payload of the link layer packet when the MTU is 1,500.
[0908] However, the present embodiment may correspond to a case in
which nine or more RoHC packets are concatenated. In this case, an
extended length part may be needed in addition to a length part. As
described in the foregoing, a count field may have a value 111.
[0909] When the number of X fields, each of which has a value 1, is
set to m in the extended length part, the number n of RoHC packets
concatenated in the payload of the link layer packet is 8+(m+1). In
this instance, a length LT of the entire link layer packet is as
follows.
L T = 1 + L LP + L ELP + k = 1 n L k [ bytes ] [ Math Figure 21 ]
##EQU00013##
[0910] Here, LLP may be a length of the entire length part, and Lk
may be a length of each of the RoHC packets. In addition, LELP may
be a length of the entire extended length part.
[0911] FIG. 87 illustrates Embodiment #7 of a method of
transmitting an RoHC packet using a link layer packet when an MTU
is 1,500, according to the present invention.
[0912] The present embodiment may correspond to a case in which a
plurality of RoHC packets are concatenated to form a payload of the
link layer packet when the MTU is 1,500. However, the present
embodiment corresponds to a case in which the concatenated RoHC
packets have the same CID.
[0913] In this case, the above-described CI field has a value 1,
which indicates that the same CID is processed. The RoHC packets
having the same CID are indicated by [R1, R2, R3, . . . , Rn]. The
CID common to the RoHC packets may be referred to as a common CID.
A packet corresponding to an RoHC packet excluding a CID from a
header is indicated by R'k (k is 1, 2, . . . , or n).
[0914] The payload of the link layer packet may include R'k (k is
1, 2, . . . , or n). A common CID field may be additionally
provided to a tail of an extended header of the link layer packet.
The common CID field may be a field for transmission of the common
CID. The common CID field may be transmitted as a portion of the
extended header or as a portion of the payload of the link layer
packet. Depending on a system operation, the common CID field may
be appropriately rearranged at a portion for verification of a
position.
[0915] The common CID field may have a size varying according to a
configuration of the RoHC packet.
[0916] When the configuration of the RoHC packet corresponds to a
small CID configuration, the RoHC packet may have a CID size of 4
bits. When rearrangement is performed by extracting a CID from the
RoHC packet, the entire add-CID octet may be processed. That is,
the common CID field may have a length of 1 byte. Alternatively,
after extracting a 1-byte add-CID octet from the RoHC packet, only
a 4-bit CID may be assigned to the common CID field, and the
remaining 4-bit CID may be reserved for later use.
[0917] When the configuration of the RoHC packet corresponds to a
large CID configuration, the RoHC packet may have a CID size of 1
byte or 2 bytes. The CID size is determined in an RoHC
initialization process. Depending on the CID size, the common CID
field may have a length of 1 byte or 2 bytes.
[0918] In this case, the entire length LT of the link layer packet
may be calculated as below.
L T = 1 + L LP + L CID + k = 1 n ( L k - L CID ) [ bytes ] [ Math
Figure 22 ] ##EQU00014##
[0919] Here, LCID may denote a length of the common CID field. As
described in the foregoing, LCID may be determined based on a CID
configuration of the RoHC packet.
[0920] Similarly, when n is greater than or equal to 9 (the count
field has a value 111B), the entire length LT of the link layer
packet may be calculated as below.
L T = 1 + L LP + L ELP + L CID + k = 1 n ( L k - L CID ) [ bytes ]
[ Math Figure 23 ] ##EQU00015##
[0921] Here, LCID may denote a length of the common CID field.
[0922] FIG. 88 illustrates a protocol stack for a hybrid-based next
generation broadcast system according to another embodiment of the
present invention.
[0923] In a hybrid-based broadcast system of a TS and an IP stream,
a link layer may be used to transmit data having a TS or IP stream
type. When various types of data are to be transmitted through a
physical layer, the link layer may convert the data into a format
supported by the physical layer and deliver the converted data to
the physical layer. In this way, the various types of data may be
transmitted through the same physical layer. Here, the physical
layer may correspond to a step of transmitting data using an
MIMO/MISO scheme or the like by interleaving, multiplexing, and/or
modulating the data.
[0924] The link layer needs to be designed such that an influence
on an operation of the link layer is minimized even when a
configuration of the physical layer is changed. In other words, the
operation of the link layer needs to be configured such that the
operation may be compatible with various physical layers.
[0925] The present invention proposes a link layer capable of
independently operating irrespective of types of an upper layer and
a lower layer. In this way, it is possible to support various upper
layers and lower layers. Here, the upper layer may refer to a layer
of a data stream such as a TS stream, an IP stream, or the like.
Here, the lower layer may refer to the physical layer. In addition,
the present invention proposes a link layer having a correctable
structure in which a function supportable by the link layer may be
extended/added/deleted. Moreover, the present invention proposes a
scheme of including an overhead reduction function in the link
layer such that radio resources may be efficiently used.
[0926] In this figure, protocols and layers such as IP, UDP, TCP,
ALC/LCT, RCP/RTCP, HTTP, FLUTE, and the like are as described
above.
[0927] In this figure, a link layer t88010 may be another example
of the above-described data link (encapsulation) part. The present
invention proposes a configuration and/or an operation of the link
layer t88010. The link layer t88010 proposed by the present
invention may process signaling necessary for operations of the
link layer and/or the physical layer. In addition, the link layer
t88010 proposed by the present invention may encapsulate TS and IP
packets and the like, and perform overhead reduction in this
process.
[0928] The link layer t88010 proposed by the present invention may
be referred to by several terms such as data link layer,
encapsulation layer, layer 2, and the like. According to a given
embodiment, a new term may be applied to the link layer and
used.
[0929] FIG. 89 illustrates an operation in a normal mode
corresponding to one of operation modes of a link layer according
to an embodiment of the present invention.
[0930] The link layer proposed by the present invention may have
various operation modes for compatibility between an upper layer
and a lower layer. The present invention proposes a normal mode and
a transparent mode of the link layer. Both the operation modes may
coexist in the link layer, and an operation mode to be used may be
designated using signaling or a system parameter. According to a
given embodiment, one of the two operation modes may be
implemented. Different modes may be applied according to an IP
layer, a TS layer, and the like input to the link layer. In
addition, different modes may be applied for each stream of the IP
layer and for each stream of the TS layer.
[0931] According to a given embodiment, a new operation mode may be
added to the link layer. The new operation mode may be added based
on configurations of the upper layer and the lower layer. The new
operation mode may include different interfaces based on the
configurations of the upper layer and the lower layer. Whether to
use the new operation mode may be designated using signaling or a
system parameter.
[0932] In the normal mode, data may be processed through all
functions supported by the link layer, and then delivered to a
physical layer.
[0933] First, each packet may be delivered to the link layer from
an IP layer, an MPEG-2 TS layer, or another particular layer
t89010. In other words, an IP packet may be delivered to the link
layer from an IP layer. Similarly, an MPEG-2 TS packet may be
delivered to the link layer from the MPEG-2 TS layer, and a
particular packet may be delivered to the link layer from a
particular protocol layer.
[0934] Each of the delivered packets may go through or not go
through an overhead reduction process t89020, and then go through
an encapsulation process t89030.
[0935] First, the IP packet may go through or not go through the
overhead reduction process t89020, and then go through the
encapsulation process t89030. Whether the overhead reduction
process t89020 is performed may be designated by signaling or a
system parameter. According to a given embodiment, the overhead
reduction process t89020 may be performed or not performed for each
IP stream. An encapsulated IP packet may be delivered to the
physical layer.
[0936] Second, the MPEG-2 TS packet may go through the overhead
reduction process t89020, and go through the encapsulation process
t89030. The MPEG-2 TS packet may not be subjected to the overhead
reduction process t89020 according to a given embodiment. However,
in general, a TS packet has sync bytes (0x47) and the like at the
front and thus it may be efficient to eliminate such fixed
overhead. The encapsulated TS packet may be delivered to the
physical layer.
[0937] Third, a packet other than the IP or TS packet may or may
not go through the overhead reduction process t89020, and then go
through the encapsulation process t89030. Whether or not the
overhead reduction process t89020 is performed may be determined
according to characteristics of the corresponding packet. Whether
the overhead reduction process t89020 is performed may be
designated by signaling or a system parameter. The encapsulated
packet may be delivered to the physical layer.
[0938] In the overhead reduction process t89020, a size of an input
packet may be reduced through an appropriate scheme. In the
overhead reduction process t89020, particular information may be
extracted from the input packet or generated. The particular
information is information related to signaling, and may be
transmitted through a signaling region. The signaling information
enables a receiver to restore an original packet by restoring
changes due to the overhead reduction process t89020. The signaling
information may be delivered to a link layer signaling process
t89050.
[0939] The link layer signaling process t89050 may transmit and
manage the signaling information extracted/generated in the
overhead reduction process t89020. The physical layer may have
physically/logically divided transmission paths for signaling, and
the link layer signaling process t89050 may deliver the signaling
information to the physical layer according to the divided
transmission paths. Here, the above-described FIC signaling process
t89060, EAS signaling process t89070, or the like may be included
in the divided transmission paths. Signaling information not
transmitted through the divided transmission paths may be delivered
to the physical layer through the encapsulation process t89030.
[0940] Signaling information managed by the link layer signaling
process t89050 may include signaling information delivered from the
upper layer, signaling information generated in the link layer, a
system parameter, and the like. Specifically, the signaling
information may include signaling information delivered from the
upper layer to be subsequently delivered to an upper layer of the
receiver, signaling information generated in the link layer to be
used for an operation of a link layer of the receiver, signaling
information generated in the upper layer or the link layer to be
used for rapid detection in a physical layer of the receiver, and
the like.
[0941] Data going through the encapsulation process t89030 and
delivered to the physical layer may be transmitted through a data
pipe (DP) t89040. Here, the DP may be a physical layer pipe (PLP).
Signaling information delivered through the above-described divided
transmission paths may be delivered through respective transmission
paths. For example, an FIC signal may be transmitted through an FIC
t89080 designated in a physical frame. In addition, an EAS signal
may be transmitted through an EAC t89090 designated in a physical
frame. Information about presence of a dedicated channel such as
the FIC, the EAC, or the like may be transmitted to a preamble area
of the physical layer through signaling, or signaled by scrambling
a preamble using a particular scrambling sequence. According to a
given embodiment, FIC signaling/EAS signaling information may be
transmitted through a general DP area, PLS area, or preamble rather
than a designated dedicated channel.
[0942] The receiver may receive data and signaling information
through the physical layer. The receiver may restore the received
data and signaling information into a form processable in the upper
layer, and deliver the restored data and signaling information to
the upper layer. This process may be performed in the link layer of
the receiver. The receiver may verify whether a received packet is
related to the signaling information or the data by reading a
header of the packet and the like. In addition, when overhead
reduction is performed at a transmitter, the receiver may restore a
packet, overhead of which has been reduced through the overhead
reduction process, to an original packet. In this process, the
received signaling information may be used.
[0943] FIG. 90 illustrates an operation in a transparent mode
corresponding to one of operation modes of a link layer according
to an embodiment of the present invention.
[0944] In the transparent mode, data may not be subjected to
functions supported by the link layer or may be subjected to some
of the functions, and then delivered to a physical layer. In other
words, in the transparent mode, a packet delivered to an upper
layer may be delivered to a physical layer without going through a
separate overhead reduction and/or encapsulation process. Other
packets may go through the overhead reduction and/or encapsulation
process as necessary. The transparent mode may be referred to as a
bypass mode, and another term may be applied to the transparent
mode.
[0945] According to a given embodiment, some packets may be
processed in the normal mode and some packets may be processed in
the transparent mode based on characteristics of the packets and a
system operation.
[0946] A packet to which the transparent mode may be applied may be
a packet having a type well known to a system. When the packet may
be processed in the physical layer, the transparent mode may be
used. For example, a well-known TS or IP packet may go through
separate overhead reduction and input formatting processes in the
physical layer and thus the transparent mode may be used in a link
layer step. When the transparent mode is applied and a packet is
processed through input formatting and the like in the physical
layer, an operation such as the above-described TS header
compression may be performed in the physical layer. On the other
hand, when the normal mode is applied, a processed link layer
packet may be treated as a GS packet and processed in the physical
layer.
[0947] In the transparent mode, a link layer signaling module may
be included when signal transmission needs to be supported. As
described above, the link layer signaling module may transmit and
manage signaling information. The signaling information may be
encapsulated and transmitted through a DP, and FIC signaling
information and EAS signaling information having divided
transmission paths may be transmitted through an FIC and an EAC,
respectively.
[0948] In the transparent mode, whether information corresponds to
signaling information may be displayed using a fixed IP address and
port number. In this case, the signaling information may be
filtered to configure a link layer packet, and then transmitted
through the physical layer.
[0949] FIG. 91 illustrates a configuration of a link layer at a
transmitter according to an embodiment of the present invention
(normal mode).
[0950] The present embodiment is an embodiment presuming that an IP
packet is processed. The link layer at the transmitter may largely
include a link layer signaling part for processing signaling
information, an overhead reduction part, and/or an encapsulation
part from a functional perspective. The link layer at the
transmitter may further include a scheduler t91020 for a control of
the entire operation of the link layer and scheduling, input and
output parts of the link layer, and/or the like.
[0951] First, upper layer signaling information and/or system
parameter t91010 may be delivered to the link layer. In addition,
an IP stream including IP packets may be delivered to the link
layer from an IP layer t91110.
[0952] As described above, the scheduler t91020 may determine and
control operations of several modules included in the link layer.
The delivered signaling information and/or system parameter t91010
may be filtered or used by the scheduler t91020. Information
corresponding to a part of the delivered signaling information
and/or system parameter t91010 and necessary for a receiver may be
delivered to the link layer signaling part. In addition,
information corresponding to a part of the signaling information
and necessary for an operation of the link layer may be delivered
to an overhead reduction control block t91120 or an encapsulation
control block t91180.
[0953] The link layer signaling part may collect information to be
transmitted as signaling in the physical layer, and
transform/configure the information in a form suitable for
transmission. The link layer signaling part may include a signaling
manager t91030, a signaling formatter t91040, and/or a buffer for
channels t91050.
[0954] The signaling manager t91030 may receive signaling
information delivered from the scheduler t91020, signaling
delivered from the overhead reduction part, and/or context
information. The signaling manager t91030 may determine paths for
transmission of the signaling information with respect to delivered
data. The signaling information may be delivered through the paths
determined by the signaling manager t91030. As described in the
foregoing, signaling information to be transmitted through divided
channels such as an FIC, an EAS, and the like may be delivered to
the signaling formatter t91040, and other signaling information may
be delivered to an encapsulation buffer t91070.
[0955] The signaling formatter t91040 may format associated
signaling information in forms suitable for respective divided
channels so that the signaling information may be transmitted
through separately divided channels. As described in the foregoing,
the physical layer may include physically/logically divided
separate channels. The divided channels may be used to transmit FIC
signaling information or EAS-related information. The FIC or
EAS-related information may be divided by the signaling manager
t91030 and input to the signaling formatter t91040. The signaling
formatter t91040 may format information such that the information
is suitable for respective separate channels. Besides the FIC and
the EAS, when the physical layer is designed to transmit particular
signaling information through separately divided channels, a
signaling formatter for the particular signaling information may be
added. Through this scheme, the link layer may be compatible with
various physical layers.
[0956] The buffer for channels t91050 may deliver signaling
information delivered from the signaling formatter t91040 to
designated dedicated channels t91060. The number and content of the
dedicated channels t91060 may vary depending on an embodiment.
[0957] As described in the foregoing, the signaling manager t91030
may deliver signaling information which is not delivered to a
dedicated channel to the encapsulation buffer t91070. The
encapsulation buffer t91070 may function as a buffer that receives
the signaling information not delivered to the dedicated
channel.
[0958] An encapsulation for signaling information t91080 may
encapsulate the signaling information not delivered to the
dedicated channel. A transmission buffer t91090 may function as a
buffer that delivers the encapsulated signaling information to a DP
for signaling information t91100. Here, the DP for signaling
information t91100 may refer to the above-described PLS area.
[0959] The overhead reduction part may allow efficient transmission
by eliminating overhead of packets delivered to the link layer. It
is possible to configure overhead reduction parts, the number of
which is the same as the number of IP streams input to the link
layer.
[0960] An overhead reduction buffer t91130 may receive an IP packet
delivered from an upper layer. The delivered IP packet may be input
to the overhead reduction part through the overhead reduction
buffer t91130.
[0961] An overhead reduction control block t91120 may determine
whether to perform overhead reduction on a packet stream input to
the overhead reduction buffer t91130. The overhead reduction
control block t91120 may determine whether to perform overhead
reduction for each packet stream. When overhead reduction is
performed on the packet stream, packets may be delivered to an RoHC
compressor t91140 and overhead reduction may be performed. When
overhead reduction is not performed on the packet stream, packets
may be delivered to the encapsulation part and encapsulation may be
performed without overhead reduction. Whether to perform overhead
reduction on packets may be determined by signaling information
t91010 delivered to the link layer. The signaling information
t91010 may be delivered to the encapsulation control block t91180
by the scheduler t91020.
[0962] The RoHC compressor t91140 may perform overhead reduction on
a packet stream. The RoHC compressor t91140 may compress headers of
packets. Various schemes may be used for overhead reduction.
Overhead reduction may be performed by schemes proposed in the
present invention. The present embodiment presumes an IP stream and
thus the compressor is expressed as the RoHC compressor. However,
the term may be changed according to a given embodiment. In
addition, an operation is not restricted to compression of an IP
stream, and overhead reduction may be performed on all types of
packets by the RoHC compressor t91140.
[0963] A packet stream configuration block t91150 may divide IP
packets having compressed headers into information to be
transmitted to a signaling region and information to be transmitted
to a packet stream. The information to be transmitted to the packet
stream may refer to information to be transmitted to a DP area. The
information to be transmitted to the signaling region may be
delivered to a signaling and/or context control block t91160. The
information to be transmitted to the packet stream may be
transmitted to the encapsulation part.
[0964] The signaling and/or context control block t91160 may
collect signaling and/or context information and deliver the
collected information to the signaling manager t91030. In this way,
the signaling and/or context information may be transmitted to the
signaling region.
[0965] The encapsulation part may encapsulate packets in suitable
forms such that the packets may be delivered to the physical layer.
The number of configured encapsulation parts may be the same as the
number of IP streams.
[0966] An encapsulation buffer t91170 may receive a packet stream
for encapsulation. Packets subjected to overhead reduction may be
received when overhead reduction is performed, and an input IP
packet may be received without change when overhead reduction is
not performed.
[0967] An encapsulation control block t91180 may determine whether
to perform encapsulation on an input packet stream. When
encapsulation is performed, the packet stream may be delivered to
segmentation/concatenation t91190. When encapsulation is not
performed, the packet stream may be delivered to a transmission
buffer t91230. Whether to perform encapsulation of packets may be
determined based on the signaling information t91010 delivered to
the link layer. The signaling information t91010 may be delivered
to the encapsulation control block t91180 by the scheduler
t91020.
[0968] In the segmentation/concatenation t91190, the above-descried
segmentation or concatenation operation may be performed on
packets. In other words, when an input IP packet is longer than a
link layer packet corresponding to an output of the link layer, one
IP packet may be divided into several segments to configure a
plurality of link layer packet payloads. In addition, when the
input IP packet is shorter than the link layer packet corresponding
to the output of the link layer, several IP packets may be combined
to configure one link layer packet payload.
[0969] A packet configuration table t91200 may have information
about a configuration of segmented and/or concatenated link layer
packets. A transmitter and a receiver may have the same information
of the packet configuration table t91200. The transmitter and the
receiver may refer to the information of the packet configuration
table t91200. An index value of the information of the packet
configuration table t91200 may be included in headers of the link
layer packets.
[0970] A link layer header information block t91210 may collect
header information generated in an encapsulation process. In
addition, the link layer header information block t91210 may
collect information included in the packet configuration table
t91200. The link layer header information block t91210 may
configure header information according to a header configuration of
a link layer packet.
[0971] A header attachment block t91220 may add headers to payloads
of the segmented and/or concatenated link layer packets. The
transmission buffer t91230 may function as a buffer for delivering
a link layer packet to a DP t91240 of the physical layer.
[0972] Each block or module and parts may be configured as one
module/protocol or a plurality of modules/protocols in the link
layer.
[0973] FIG. 92 illustrates a configuration of a link layer at a
receiver according to an embodiment of the present invention
(normal mode).
[0974] The present embodiment is an embodiment presuming that an IP
packet is processed. The link layer at the receiver may largely
include a link layer signaling part for processing signaling
information, an overhead processing part, and/or a decapsulation
part from a functional perspective. The link layer at the receiver
may further include a scheduler for a control of the entire
operation of the link layer and scheduling, input and output parts
of the link layer, and/or the like.
[0975] First, information received through a physical layer may be
delivered to the link layer. The link layer may process the
information to restore the information to an original state in
which the information is not yet processed by a transmitter, and
deliver the information to an upper layer. In the present
embodiment, the upper layer may be an IP layer.
[0976] Information delivered through dedicated channels t92030
separated from the physical layer may be delivered to the link
layer signaling part. The link layer signaling part may distinguish
signaling information received from the physical layer, and deliver
the distinguished signaling information to each part of the link
layer.
[0977] A buffer for channels t92040 may function as a buffer that
receives signaling information transmitted through the dedicated
channels. As described above, when physically/logically divided
separate channels are present in the physical layer, it is possible
to receive signaling information transmitted through the channels.
When the information received from the separate channels is in a
divided state, the divided information may be stored until the
information is in a complete form.
[0978] A signaling decoder/parser t92050 may check a format of
signaling information received through a dedicated channel, and
extract information to be used in the link layer. When the
signaling information received through the dedicated channel is
encoded, decoding may be performed. In addition, according to a
given embodiment, it is possible to check integrity of the
signaling information.
[0979] A signaling manager t92060 may integrate signaling
information received through several paths. Signaling information
received through a DP for signaling t92070 to be described below
may be integrated by the signaling manager t92060. The signaling
manager t92060 may deliver signaling information necessary for each
part in the link layer. For example, context information for
recovery of a packet and the like may be delivered to the overhead
processing part. In addition, signaling information for control may
be delivered to a scheduler t92020.
[0980] General signaling information not received through a
separate dedicated channel may be received through the DP for
signaling t92070. Here, the DP for signaling may refer to a PLS or
the like. A reception buffer t92080 may function as a buffer for
receiving the signaling information received from the DP for
signaling t92070. The received signaling information may be
decapsulated in a decapsulation for signaling information block
t92090. The decapsulated signaling information may be delivered to
the signaling manager t92060 through a decapsulation buffer t92100.
As described in the foregoing, the signaling manager t92060 may
collect signaling information and deliver the collected signaling
information to a desired part in the link layer.
[0981] The scheduler t92020 may determine and control operations of
several modules included in the link layer. The scheduler t92020
may control each part of the link layer using receiver information
t92010 and/or information delivered from the signaling manager
t92060. In addition, the scheduler t92020 may determine an
operation mode and the like of each part. Here, the receiver
information t92010 may refer to information previously stored by
the receiver. The scheduler t92020 may use information changed by a
user such as a channel change and the like for control.
[0982] The decapsulation part may filter a packet received from a
DP t92110 of the physical layer, and separate the packet based on a
type of the packet. The number of configured decapsulation parts
may be the same as the number of DPs that may be simultaneously
decoded in the physical layer.
[0983] A decapsulation buffer t92120 may function as a buffer that
receives a packet stream from the physical layer to perform
decapsulation. A decapsulation control block t92130 may determine
whether to decapsulate the received packet stream. When
decapsulation is performed, the packet stream may be delivered to a
link layer header parser t92140. When decapsulation is not
performed, the packet stream may be delivered to an output buffer
t92220. The signaling information delivered from the scheduler
t92020 may be used to determine whether to perform
decapsulation.
[0984] The link layer header parser t92140 may identify a header of
a received link layer packet. When the header is identified, it is
possible to identify a configuration of an IP packet included in a
payload of the link layer packet. For example, the IP packet may be
segmented or concatenated.
[0985] A packet configuration table t92150 may include payload
information of link layer packets configured through segmentation
and/or concatenation. The transmitter and the receiver may have the
same information as information of the packet configuration table
t92150. The transmitter and the receiver may refer to the
information of the packet configuration table t92150. A value
necessary for reassembly may be found based on index information
included in the link layer packets.
[0986] A reassembly block t92160 may configure payloads of the link
layer packets configured through segmentation and/or concatenation
as packets of an original IP stream. The reassembly block t92160
may reconfigure one IP packet by collecting segments, or
reconfigure a plurality of IP packet streams by separating
concatenated packets. The reassembled IP packets may be delivered
to the overhead processing part.
[0987] The overhead processing part may perform a reverse process
of overhead reduction performed by the transmitter. In the reverse
process, an operation of returning packets experiencing overhead
reduction to original packets is performed. This operation may be
referred to as overhead processing. The number of configured
overhead processing parts may be the same as the number of DPs that
may be simultaneously decoded in the physical layer.
[0988] A packet recovery buffer t92170 may function as a buffer
that receives an RoHC packet or an IP packet decapsulated for
overhead processing.
[0989] An overhead control block t92180 may determine whether to
perform packet recovery and/or decompression of decapsulated
packets. When the packet recovery and/or decompression are
performed, the packets may be delivered to a packet stream recovery
t92190. When the packet recovery and/or decompression are not
performed, the packets may be delivered to the output buffer
t92220. Whether to perform the packet recovery and/or decompression
may be determined based on the signaling information delivered by
the scheduler t92020.
[0990] The packet stream recovery t92190 may perform an operation
of integrating a packet stream separated from the transmitter and
context information of the packet stream. The operation may
correspond to a process of restoring the packet stream such that
the packet stream may be processed by an RoHC decompressor t92210.
In this process, signaling information and/or context information
may be delivered from a signaling and/or context control block
t92200. The signaling and/or context control block t92200 may
distinguish signaling information delivered from the transmitter
and deliver the signaling information to the packet stream recovery
t92190 such that the signaling information may be mapped to a
stream suitable for a context ID.
[0991] The RoHC decompressor t92210 may recover headers of packets
of a packet stream. When the headers are recovered, the packets of
the packet stream may be restored to original IP packets. In other
words, the RoHC decompressor t92210 may perform overhead
processing.
[0992] The output buffer t92220 may function as a buffer before
delivering an output stream to an IP layer t92230.
[0993] The link layer of the transmitter and the receiver proposed
in the present invention may include the blocks or modules
described above. In this way, the link layer may independently
operate irrespective of the upper layer and the lower layer, and
efficiently perform overhead reduction. In addition, a function
which is supportable depending on the upper and lower layers may be
easily extended/added/deleted.
[0994] FIG. 93 illustrates a method of transmitting broadcast
signals according to an embodiment of the present invention.
[0995] The method includes generating plural input streams, link
layer processing the input packets, physical layer processing the
link layer packets and/or transmitting the generated broadcast
signals.
[0996] In step of generating plural input streams, the input
streams including plural input packets can be generated in upper
layer. Upper layer can be either TS layer, IP layer or other types
of packet layer. Therefore, the input packets can be either TS
packets, IP packets or other packets. Input stream includes
consecutive input packets.
[0997] In step of link layer processing the input packets, the
input packets can be processed by the link layer described above.
The link layer can be the one suggested by the present invention.
By processing input packets in the link layer, the link layer
packets can be generated. By processing any types of input packets
into the link layer packet, any input streams can be processed by
the physical layer.
[0998] In step of physical layer processing the link layer packets,
the link layer packets can be processed in physical layer. The link
layer packets can go through interleaving, frame mapping, and/or
modulating and so on. With this process, the broadcast signals can
be generated.
[0999] In step of transmitting the generated broadcast signals, the
broadcast signals can be transmitted by either SISO, MISO, or MIMO.
The transmitting can be included in physical layer.
[1000] In a method of transmitting broadcast signals according to
other embodiment of the present invention, the link layer
processing includes link layer processing one of the plural input
streams based on transparent mode. As described above, there can be
two modes for link layer processing, normal and transparent. In
link layer processing, some of input streams can be processed in
transparent mode, while the others are processed in normal mode. In
transparent mode, the link layer delivers the one of the plural
input streams to the physical layer without encapsulating.
Signaling information supposed to be transmitted in a dedicated
channel, can be delivered to that channel in the physical layer.
Some types of packets can go through encapsulating, even in the
transparent mode, as described above.
[1001] In a method of transmitting broadcast signals according to
another embodiment of the present invention, the link layer
processing in normal mode includes encapsulating and/or delivering.
The link layer processing one of the plural input streams includes
encapsulating the input packets in the one of the plural input
streams to generate the link layer packets. The generated link
layer packets can be delivered to the physical layer.
[1002] In a method of transmitting broadcast signals according to
another embodiment of the present invention, the link layer
processing in normal mode includes overhead reduction processing
the input packets before encapsulating. The overhead reduction
process can be conducted after the encapsulating in other
embodiments. The overhead reduction process can include compress
headers of the input packets. Other method of overhead reduction
can be used in link layer.
[1003] In a method of transmitting broadcast signals according to
another embodiment of the present invention, the link layer
processing in normal mode includes extracting a first signaling
information and/or delivering. The first signaling information can
be extracted from overhead reduction processed input packets. The
first signaling information is a signaling information to be
transmitted in a dedicated transmission channel. The above
described EAS, FIC information can correspond to the first
signaling information. The first signaling information can be
delivered to the dedicated channel for the first signaling
information, in the physical layer.
[1004] In a method of transmitting broadcast signals according to
another embodiment of the present invention, the link layer
processing in normal mode includes extracting a second signaling
information, encapsulating the second signaling information and/or
delivering. The second signaling information is for signaling data
in the input packets. The second signaling information can be
encapsulated as in the encapsulation of input packets. The second
signaling information can be encapsulated into the link layer
packets. The link layer packet generated by using the second
signaling information can be delivered to the physical layer. The
second signaling information can be transmitted in DP or PLS, as
described above.
[1005] In a method of transmitting broadcast signals according to
another embodiment of the present invention, the link layer packet
includes a link layer payload generated by using a segment of one
of the input packets, or by using concatenated input packets. As
described above, the link layer payload can be encapsulated by
segmentation or concatenation. Various methods of segmentation and
concatenation have been described.
[1006] Segmentation and concatenation methods for each types of
input packets can be used in encapsulation. Whether the
segmentation or the concatenation is used can be decided based on
signaling information.
[1007] In a method of transmitting broadcast signals according to
another embodiment of the present invention, the physical layer
processing includes physical layer processing plural Plops
(Physical Layer Pipes). The PLP may correspond to the DP. The PLP
can include data of the link layer packets, and be processed in
physical layer. The link layer can be processed in physical layer
as in forms of Plops.
[1008] In a method of transmitting broadcast signals according to
another embodiment of the present invention, the physical layer
processing includes physical layer processing the first signaling
information. The first signaling information can be processed into
the dedicated transmission channel, to generate the broadcast
signals.
[1009] In a method of transmitting broadcast signals according to
another embodiment of the present invention, the input packets are
one of TS (Transport Stream) packet, IP (Internet Protocol) packet
or GS (Generic Stream) packet. The input packets can be some types
of packets other than TS, IP or GS packets.
[1010] The above-described steps can be omitted or replaced by
steps executing similar or identical functions according to
design.
[1011] A module or a unit is a processor executing a sequence of
instructions stored in a memory (or storage unit). The steps in
above described embodiments can be operated in hardware/processors.
The first module, second module, third module and/or fourth module
can be operated as hardware/processors. In addition, a method of
transmitting broadcast signals according to an embodiment of the
present invention may be implemented as code that may be written on
a processor readable recording medium and thus, read by a processor
provided in the apparatus.
[1012] Although the description of the present invention is
explained with reference to each of the accompanying drawings for
clarity, it is possible to design new embodiment(s) by merging the
embodiments shown in the accompanying drawings with each other.
And, if a recording medium readable by a computer, in which
programs for executing the embodiments mentioned in the foregoing
description are recorded, is designed in necessity of those skilled
in the art, it may belong to the scope of the appended claims and
their equivalents.
[1013] An apparatus and method according to the present invention
may be non-limited by the configurations and methods of the
embodiments mentioned in the foregoing description. And, the
embodiments mentioned in the foregoing description can be
configured in a manner of being selectively combined with one
another entirely or in part to enable various modifications.
[1014] In addition, a method according to the present invention can
be implemented with processor-readable codes in a
processor-readable recording medium provided to a network device.
The processor-readable medium may include all kinds of recording
devices capable of storing data readable by a processor. The
processor-readable medium may include one of ROM, RAM, CD-ROM,
magnetic tapes, floppy discs, optical data storage devices, and the
like for example and also include such a carrier-wave type
implementation as a transmission via Internet. Furthermore, as the
processor-readable recording medium is distributed to a computer
system connected via network, processor-readable codes can be saved
and executed according to a distributive system.
[1015] It will be appreciated by those skilled in the art that
various modifications and variations can be made in the present
invention without departing from the spirit or scope of the
inventions. Thus, it is intended that the present invention covers
the modifications and variations of this invention provided they
come within the scope of the appended claims and their
equivalents.
[1016] Both apparatus and method inventions are mentioned in this
specification and descriptions of both of the apparatus and method
inventions may be complementarily applicable to each other.
[1017] Various embodiments have been described in the best mode for
carrying out the invention.
[1018] The present invention is available in a series of broadcast
signal provision fields.
[1019] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the inventions. Thus,
it is intended that the present invention covers the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *