U.S. patent application number 13/974594 was filed with the patent office on 2013-12-26 for compact specification of data allocations.
This patent application is currently assigned to Wi-LAN, Inc.. The applicant listed for this patent is Wi-LAN, Inc.. Invention is credited to Dennis Connors, Yoav Nebat, Sina Zehedi.
Application Number | 20130343258 13/974594 |
Document ID | / |
Family ID | 40721654 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130343258 |
Kind Code |
A1 |
Zehedi; Sina ; et
al. |
December 26, 2013 |
COMPACT SPECIFICATION OF DATA ALLOCATIONS
Abstract
The subject matter disclosed herein provides a mechanism for
numbering OFDMA symbols in data regions of OFDMA frames. The method
may include assigning, based on a pattern vector, one or more
numbers to one or more symbols of a time diversity interval.
Moreover, the one or more numbered symbols may be assigned to one
or more segments. The pattern vector is then provided to a client
station to enable the client station to access, based on the
numbered one or more symbols, at least one of the segments. Related
systems, apparatus, methods, and/or articles are also
described.
Inventors: |
Zehedi; Sina; (San Diego,
CA) ; Nebat; Yoav; (San Diego, CA) ; Connors;
Dennis; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Wi-LAN, Inc. |
Ottawa |
|
CA |
|
|
Assignee: |
Wi-LAN, Inc.
Ottawa
CA
|
Family ID: |
40721654 |
Appl. No.: |
13/974594 |
Filed: |
August 23, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12202187 |
Aug 29, 2008 |
8547953 |
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13974594 |
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61060117 |
Jun 9, 2008 |
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61024507 |
Jan 29, 2008 |
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61019572 |
Jan 7, 2008 |
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61007360 |
Dec 11, 2007 |
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Current U.S.
Class: |
370/312 ;
370/329 |
Current CPC
Class: |
H04L 1/0084 20130101;
H04W 72/005 20130101; H03M 13/09 20130101 |
Class at
Publication: |
370/312 ;
370/329 |
International
Class: |
H04W 72/00 20060101
H04W072/00 |
Claims
1. A method comprising: receiving, at a client station, a pattern
vector; determining, based on the pattern vector, a symbol number
indicating a start of a segment; and receiving the segment based on
the determined symbol number, the segment including a group of
numbered orthogonal frequency division multiple access (OFDMA)
symbols carrying a stream of packets.
2. The method of claim 1 further comprising: using, as the pattern
vector, one or more values defining one or more widths of one or
more multicast and broadcast service regions of a time diversity
interval, the one or more multicast and broadcast service regions
transmitted from a plurality of base stations using
macrodiversity.
3. The method of claim 1, wherein determining the symbol number
indicating the start of the segment further comprises: determining
an orthogonal frequency division multiple access (OFDMA) frame
including the symbol number; and determining a location of the
symbol number within the determined OFDMA frame, the determined
OFDMA frame included within a time diversity interval comprising a
plurality of OFDMA frames.
4. The method of claim 1, wherein receiving the segment further
comprises: receiving the segment within one or more multicast and
broadcast service regions transmitted from a plurality of base
stations using macrodiversity.
5. The method of claim 1 further comprising: determining, based on
a period of the pattern vector, another symbol number indicating
another start of another segment located within the same time
diversity as the segment.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/202,187, filed Aug. 29, 2008, which claims
the benefit of U.S. Provisional Application No. 61/060,117 filed
Jun. 9, 2008, U.S. Provisional Application No. 61/024,507, filed
Jan. 29, 2008, U.S. Provisional Application No. 61/019,572, filed
Jan. 7, 2008 and U.S. Provisional Application No. 61/007,360, filed
Dec. 11, 2007, all of which are incorporated by reference as if
fully set forth.
FIELD OF INVENTION
[0002] The subject matter described herein relates to wireless
communications.
BACKGROUND
[0003] Multicast and broadcast service (MBS) refers generally to
sending information to a plurality of receivers. Macrodiversity MBS
is a specific type of transmission, in which a plurality of base
stations transmit synchronously. When using macrodiversity (MD), a
plurality of base stations synchronously transmit at about the same
frequency, using about the same waveform, and using about the same
framing parameters. Macrodiversity is also referred to as a single
frequency network (SFN).
[0004] At a receiver, such as a client station, macrodiversity
provides a so-called "macrodiversity gain" by combining the
synchronous broadcasts transmitted by the base stations--providing
at the receiver the macrodiversity gain resulting from the combined
waveforms. IEEE-802.16 is just one of the standards that support
both MBS and macrodiversity. IEEE 802.16 refers to one or more
specifications, such as the Institute of Electrical and Electronic
Engineers (IEEE) Standard for Local and metropolitan area networks,
Part 16: Air Interface for Fixed Broadband Wireless Access Systems,
1 Oct. 2004, the IEEE Standard for Local and metropolitan area
networks, Part 16: Air Interface for Fixed and Mobile Broadband
Wireless Access Systems, 26 Feb. 2006, and subsequent revisions and
additions to those standards.
[0005] FIG. 7 depicts an example of OFDMA frames 710A-D used in
connection with a MBS transmission consistent with IEEE 802.16. The
OFDMA frames 710A-D include regions, such as MBS regions 712A-D,
transmitted in a downlink from a base station to a client station.
These regions represent one or more OFDMA symbols (or simply
symbols) carrying the content (e.g., packets) of the multicast and
broadcast service. When macrodiversity is used, the base stations
synchronously transmit an MBS region (e.g., the first symbol of an
MBS region is transmitted at about the same time at each of the
base stations). In accordance with IEEE 802.16, the MBS regions
712A-D are described by MBS maps 714A-D. The client station uses
information in the MBS map as well as other management messages
sent from the base station to the client station to decode the data
content in the MBS regions to form packets for use at the client
station.
SUMMARY
[0006] The subject matter disclosed herein provides a mechanism for
numbering OFDMA symbols in data regions, such as multicast and
broadcast service (MBS) regions of OFDMA frames.
[0007] In one aspect, there is provided a method. The method may
include assigning, based on a pattern vector, one or more numbers
to one or more symbols of a time diversity interval. Moreover, the
one or more numbered symbols may be assigned to one or more
segments. The pattern vector is then provided to a client station
to enable the client station to access, based on the numbered one
or more symbols, at least one of the segments.
[0008] In another aspect, there is provided a method. The method
may include receiving, at a client station, a pattern vector;
determining, based on the pattern vector, a symbol number
indicating a start of a segment; and receiving the segment based on
the determined symbol number, the segment including a group of
numbered orthogonal frequency division multiple access (OFDMA)
symbols carrying a stream of packets.
[0009] In another aspect, there is provided a system. The system
may include means for assigning, based on a pattern vector, one or
more numbers to one or more symbols of a time diversity interval;
means for assigning the one or more numbered symbols to one or more
segments; and means for providing to a client station the pattern
vector to enable the client station to access, based on the
numbered one or more symbols, at least one of the segments.
[0010] In yet another aspect, there is provided a system. The
system may include means for receiving, at a client station, a
pattern vector; means for determining, based on the pattern vector,
a symbol number indicating a start of a segment; and means for
receiving the segment based on the determined symbol number, the
segment including a group of numbered orthogonal frequency division
multiple access (OFDMA) symbols carrying a stream of packets.
[0011] In yet another aspect, there is provided a computer-readable
medium containing instructions to configure a processor to perform
a method including assigning, based on a pattern vector, one or
more numbers to one or more symbols of a time diversity interval;
assigning the one or more numbered symbols to one or more segments;
and providing to a client station the pattern vector to enable the
client station to access, based on the numbered one or more
symbols, at least one of the segments.
[0012] In yet another aspect, there is provided a computer-readable
medium containing instructions to configure a processor to perform
a method including receiving, at a client station, a pattern
vector; determining, based on the pattern vector, a symbol number
indicating a start of a segment; and receiving the segment based on
the determined symbol number, the segment including a group of
numbered orthogonal frequency division multiple access (OFDMA)
symbols carrying a stream of packets.
[0013] In still yet another aspect, there is provided a system. The
system may include a numbering module configured to assign, based
on a pattern vector, one or more numbers to one or more symbols of
a time diversity interval. Moreover, the numbering module may be
configured to assign the one or more numbered symbols to one or
more segments. Furthermore, the numbering module may be configured
to provide the pattern vector to enable a client station to access,
based on the numbered one or more symbols, at least one of the
segments.
[0014] In still yet another aspect, there is provided a system. The
system may include a client station. The system may also include a
numbering module configured to receive, at a client station, a
pattern vector. Moreover, the numbering module may be configured to
determine, based on the pattern vector, a symbol number indicating
a start of a segment. Furthermore, the numbering module may be
configured to receive the segment based on the determined symbol
number, the segment including a group of numbered orthogonal
frequency division multiple access (OFDMA) symbols carrying a
stream of packets.
[0015] Variations of the above aspects may include one or more of
the following features. The pattern vector may use one or more
values defining one or more widths of one or more multicast and
broadcast service regions of a time diversity interval. The pattern
vector may also use a first value representing a first width of a
first multicast and broadcast service region, a second value
representing a second width of a second multicast and broadcast
service region, a third value representing a third width of a third
multicast and broadcast service region, the first, second, and
third multicast and broadcast service regions included within a
time diversity interval. The assignment, based on the pattern
vector, may include numbering each of the orthogonal frequency
division multiple access (OFDMA) symbols of multicast and broadcast
service regions included within a time diversity interval, and the
assignment may be made without regard to boundaries associated with
multicast and broadcast service regions. A segment may include a
group of numbered orthogonal frequency division multiple access
(OFDMA) symbols carrying a stream of packets within one or more
multicast and broadcast service regions. A segment may be accessed,
based on the pattern vector, by receiving a stream of packets
carried by the at least one segment.
[0016] The details of one or more variations of the subject matter
described herein are set forth in the accompanying drawings and the
description below. Features and advantages of the subject matter
described herein will be apparent from the description and
drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In the drawings,
[0018] FIG. 1 depicts a block diagram of a network including client
stations and base stations;
[0019] FIG. 2 depicts a block diagram of a numbering system applied
across MBS regions;
[0020] FIG. 3 depicts another block diagram of a numbering system
applied across MBS regions;
[0021] FIG. 4 depicts a block diagram of a network including a
macrodiversity controller;
[0022] FIG. 5 depicts a process 500 for assigning, at a base
station, the numbering system to OFDMA symbols;
[0023] FIG. 6 depicts a process 600 for using, at a client station,
the numbering system; and
[0024] FIG. 7 depicts a block diagram of OFDMA frames consistent
with IEEE 802.16.
[0025] Like labels are used to refer to same or similar items in
the drawings.
DETAILED DESCRIPTION
[0026] The subject matter described herein relates to a numbering
system that consecutively numbers the symbols of multiple data
regions. In some implementations, the numbering system may
consecutively number the OFDMA symbols of a data region of an OFDMA
data frame. For exemplary purposes, the data region will be assumed
to be a data region for transmitting multicast and/or broadcast
data, which will be referred to herein as a multicast and broadcast
service (MBS) region. However, the ideas discussed herein are
equally applicable to other types of data regions and data
frames.
[0027] Moreover, the numbering system may define a pattern vector
(also referred to as a pattern), the elements of which compactly
define the width of the MBS regions and how to number OFDMA symbols
in the MBS regions. The base station provides numbering system
information, such as the pattern vector, to a client station to
enable the client station to access, based on the pattern vector,
OFDMA symbols in the MBS regions. Further description of the
numbering system including the pattern vector is provided below
after the following general overview of the network 100 of FIG.
1.
[0028] FIG. 1 is a simplified functional block diagram of an
embodiment of a wireless communication system 100. The wireless
communication system 100 includes a plurality of base stations 110A
and 110B, each supporting a corresponding service or coverage area
112A and 112B. The base stations are capable of communicating with
wireless devices within their coverage areas. For example, the
first base station 110A is capable of wirelessly communicating with
a first client station 114A and a second client station 114B within
the coverage area 112A. The first client station 114A is also
within the coverage area 112B and is capable of communicating with
the second base station 110B. In this description, the
communication path from the base station to the client station is
referred to as a downlink 116A and the communication path from the
client station to the base station is referred to as an uplink
116B.
[0029] Although for simplicity only two base stations are shown in
FIG. 1, a typical wireless communication system 100 includes a much
larger number of base stations. The base stations 110A and 110B can
be configured as cellular base station transceiver subsystems,
gateways, access points, radio frequency (RF) repeaters, frame
repeaters, nodes, or any wireless network entry point.
[0030] The base stations 110A and 110B can be configured to support
an omni-directional coverage area or a sectored coverage area. For
example, the second base station 110B is depicted as supporting the
sectored coverage area 112B. The coverage area 112B is depicted as
having three sectors, 118A, 118B, and 118C. In typical embodiments,
the second base station 110B treats each sector 118 as effectively
a distinct coverage area.
[0031] Although only two client stations 114A and 114B are shown in
the wireless communication system 100, typical systems are
configured to support a large number of client stations. The client
stations 114A and 114B can be mobile, nomadic, or stationary units.
The client stations 114A and 114B are often referred to as, for
example, mobile stations, mobile units, subscriber stations,
wireless terminals, or the like. A client station can be, for
example, a wireless handheld device, a vehicle mounted device, a
portable device, client premise equipment, a fixed location device,
a wireless plug-in accessory or the like. In some cases, a client
station can take the form of a handheld computer, notebook
computer, wireless telephone, personal digital assistant, wireless
email device, personal media player, meter reading equipment or the
like, and may include a display mechanism, microphone, speaker and
memory.
[0032] In a typical system, the base stations 110A and 110B also
communicate with each other and a network control module 124 over
backhaul links 122A and 122B. The backhaul links 122A and 122B may
include wired and wireless communication links. The network control
module 124 provides network administration and coordination as well
as other overhead, coupling, and supervisory functions for the
wireless communication system 100.
[0033] In some embodiments, the wireless communication system 100
can be configured to support both bidirectional communication and
unidirectional communication. In a bidirectional network, the
client station is capable of both receiving information from and
providing information to the wireless communications network.
Applications operating over the bidirectional communications
channel include traditional voice and data applications. In a
unidirectional network, the client station is capable of receiving
information from the wireless communications network but may have
limited or no ability to provide information to the network.
Applications operating over the unidirectional communications
channel include broadcast and multicast applications. In one
embodiment, the wireless system 100 supports both bidirectional and
unidirectional communications. In such an embodiment, the network
control module 124 is also coupled to external entities via, for
example, content link 126 (e.g., a source of digital video and/or
multimedia) and two-way traffic link 128.
[0034] The wireless communication system 100 can be configured to
use Orthogonal Frequency Division Multiple Access (OFDMA)
communication techniques. For example, the wireless communication
system 100 can be configured to substantially comply with a
standard system specification, such as IEEE 802.16 and its progeny
or some other wireless standard such as, for example, WiBro, WiFi,
Long Term Evolution (LTE), or it may be a proprietary system. The
subject matter described herein is not limited to application to
OFDMA systems or to the noted standards and specifications. The
description in the context of an OFDMA system is offered for the
purposes of providing a particular example only.
[0035] In some embodiments, downlink 116A and uplink 116B each
represent a radio frequency (RF) signal. The RF signal may include
data, such as voice, video, images, Internet Protocol (IP) packets,
control information, and any other type of information. When
IEEE-802.16 is used, the RF signal may use OFDMA. OFDMA is a
multi-user version of orthogonal frequency division multiplexing
(OFDM). In OFDMA, multiple access is achieved by assigning to
individual users groups of subcarriers (also referred to as tones)
and/or groups of symbol periods. The subcarriers are modulated
using BPSK (binary phase shift keying), QPSK (quadrature phase
shift keying), QAM (quadrature amplitude modulation), and carry
OFDMA symbols including data coded using a forward error-correction
code. The OFDMA symbols thus comprise one or more subcarriers.
[0036] The subject matter described herein relates to a numbering
system that consecutively numbers the OFDMA symbols of a plurality
of data regions. For example, the numbering system may
consecutively number the OFDMA symbols of multicast and broadcast
service (MBS) regions, although other types of regions may be used
as well.
[0037] Moreover, each of the data regions, such as the MBS regions,
may be assigned a particular width measured as a function of OFDMA
symbols. The widths of the data regions (or MBS regions) may be
specified by a pattern vector. The pattern vector may be defined as
follows: (w.sub.1, w.sub.2, . . . , w.sub.K), wherein K represents
the number of elements (e.g., widths) in the pattern vector,
w.sub.1 represents the width in OFDMA symbols of a first MBS region
in a given interval, such as a time diversity interval (described
further below), w.sub.2 represents the width in OFDMA symbols of
the second MBS region in the interval, and so forth until w.sub.K,
which represents the width in OFDMA symbols of the K.sup.th MBS
region in the time diversity interval. For example, for a pattern
vector (10,5,7), the MBS regions in consecutive frames of a time
diversity interval would be assigned widths of 10 OFDMA symbols, 5
OFDMA symbols, 7 OFDMA symbols, and then repeat, such that the next
three MBS regions would have widths of 10 OFDMA symbols, 5 OFDMA
symbols, and 7 OFDMA symbols, and so forth. The pattern vector
serves thus to compactly define the widths of the regions, such as
the MBS regions, which are typically non-contiguous (e.g., other
data is transmitted between transmission of the MBS regions).
Moreover, the pattern vector defines how to assign the consecutive
numbers (also referred to herein as symbol numbers) to each of the
MBS regions, as described further below.
[0038] FIG. 2 depicts a time interval, such as a time diversity
interval 210A, consistent with some embodiments of the invention.
The time diversity interval 210A includes one or more OFDMA frames,
such as OFDMA frames 216A-D. Each of the OFDMA frames represents a
region over which one or more OFDMA symbols are transmitted. In
some embodiments, the time diversity interval (TDI) is implemented
as a time interval, during which a group of consecutive OFDMA
frames are transmitted. An OFDMA frame may include a portion of the
frame for downlink transmissions, as depicted at downlinks 218A-D,
and a portion for uplink transmissions, as depicted at uplinks
220A-D. A downlink, such as downlink 218A, may include a frame
control header (FCH) 252A, downlink (DL) map (DL-MAP) 254A, a
unicast downlink region 256A, and a region for transmitting
multicast and/or broadcast data, such as MBS region 230A. The MBS
regions 230A-C can be transmitted by a plurality of base stations
using macrodiversity (MD). Other portions of the frames, such as
the frame control headers, downlink maps, unicast downlinks, and
uplinks can be transmitted in a non-macrodiversity manner. IEEE
802.16 is an example of a standard that supports the transmission
of OFDMA frames 216A-D as well as macrodiversity transmissions of
the MBS regions. It should be again noted that although the present
embodiment is discussed in reference to OFDMA frames including MBS
regions in accordance with IEEE 802.16, in other embodiments other
frame types and data regions may be used, such as for example,
frames in accordance with Long Term Evolution (LTE).
[0039] The MBS regions may carry content from a service. A service
may provide a stream of packets corresponding to content, such as a
video stream of packets consistent with, for example, H.264 (i.e.,
International Telecommunications Union, H.264: Advanced video
coding for generic audiovisual services video stream of packets,
November 2007). The stream may be inserted into the data regions,
such as MBS regions, for transmission by one or more base stations
to one or more client stations. Moreover, the transmission of the
MBS regions may use macrodiversity. Furthermore, the transmission
may be in a zone, such as a geographic area. To illustrate using a
broadcast television analogy, the zone may be the area of San
Diego, and the streams may each correspond to a channel of content
available in San Diego. As such, a user at a client station may
change streams (e.g., channels) to change service content at the
client station.
[0040] A stream may include one or more substreams. A substream
represents a portion of the stream. For example, a stream of H.264
video may be divided into two substreams, so that one substream
includes important content requiring more error correction and/or
more robust modulation than the other substream.
[0041] A substream may be composed of several segments. The term
"segment" refers to an allocation of OFDMA symbols that spans zero
or more OFDMA frames and resides in one or more data regions, such
as the MBS regions. Each segment is thus a set of OFDMA symbols
consecutively numbered using the numbering system described herein
(e.g., with respect to FIG. 2 below). Furthermore, the segment may
be specified with a starting OFDMA symbol number using the
numbering system described herein.
[0042] FIG. 2 also depicts a numbering system being assigned to the
OFDMA symbols across OFDMA frames and, in particular, across MBS
regions of different OFDMA frames. For example, the OFDMA symbols
of MBS region 230A are assigned symbol numbers 0-9, which
corresponds to a width of 10 OFDMA symbols. The OFDMA symbols of
MBS region 230B are assigned symbol numbers 10-15, which
corresponds to a width of 6 OFDMA symbols. OFDMA frame 216C does
not include an MBS region, which corresponds to a width of 0 OFDMA
symbols. The OFDMA symbols of MBS region 230C are assigned symbol
numbers 16-21, which corresponds to a width of 6 OFDMA symbols.
Moreover, the pattern vector, in this example, corresponds to (10,
6, 0, 6). As such, the width of the next MBS regions would be 10
OFDMA symbols, followed by an MBS region having a width of 6 OFDMA
symbols, and followed by a frame having no MBS region symbols, and
then by another MBS region having a width of 6 OFDMA symbols. Thus,
the pattern vector (10, 6, 0, 6) represents the width of the MBS
regions and the period of repetition (in this example, a period of
4), after which, if the TDI contained more than 4 OFDMA frames, the
widths in the pattern vector would repeat in subsequent MBS
regions, until the last frame in the TDI.
[0043] FIG. 2 also depicts that symbol numbers are assigned to
segments 212A-F. For example, symbol numbers 0-5 are assigned to
segment 212A; segment 212B is assigned to symbol numbers 6-9;
segment 212C is assigned to symbol numbers 10-13; segment 212D is
assigned to symbol numbers 14-21; and so forth. The segments carry
substreams (which are part of a stream as described above). For
example, symbol numbers 0-5, which is assigned to segment 212A,
carries content from stream 1 and substream 1, while symbol numbers
6-9, assigned to segment 212B, carries content from stream 1 and
substream 2.
[0044] FIG. 2 further depicts that the assigned segment allocations
associated with stream 1 and substreams 1 and 2 repeat at segments
212A-B, 212E-F, and so forth within a given time diversity
interval, such as time diversity interval 210A. Specifically, the
segments (including stream and substreams) are allocated to symbol
numbers using segment patterns. These segment patterns may be a
function of the pattern vector. Referring again to the previous
example of the pattern vector (10, 6, 0, 6) and FIG. 2, symbol
numbers 0-9 correspond to a segments including stream 1 substreams
1-2 (see segments 212A-B), and then the segment patterns repeat
with a period (also referred to as a cycle) of 4 OFDMA frames, so
that the segments including stream 1 substreams 1-2 also correspond
to symbol numbers 22-31 (see segments 212E-F of time diversity
interval 210A), and so forth at intervals of 4 OFDMA frames across
the time diversity interval. The cycle (or period) of 4, which is
equal to the period of the pattern vector is exemplary since other
values may be used as the period. Thus, the segment pattern repeats
at a period defined based on the pattern vector, which in this case
is every 4 frames. Note that a segment pattern need not span the
entire TDI. For example, the pattern may apply to a portion at the
beginning of the TDI, at the end of the TDI, or to any other
portion of the TDI.
[0045] Moreover, the segment pattern can be used for a given time
diversity interval, and for that given time diversity interval, the
allocation of segments to symbol numbers (i.e., the segment
allocation) can be defined compactly by defining the segment
pattern, which can repeat within that time diversity interval, as
noted above. However, in some embodiments, the segment structure
(which is defined by a pattern vector) for another, subsequent time
diversity interval may be implemented independently (e.g., the
subsequent time diversity interval may use a different pattern
vector than the previous time diversity interval 210A). The subject
matter described herein may thus provide a compact mechanism to
define a segment structure (as well as a resulting allocation of
segments to symbol numbers) using a pattern vector given the
numbering system described herein. The numbering system may thus
enable a client station to receive and decode a stream of interest
across segments within a given time diversity interval based on the
numbering system. For example, a client station interested in
selecting stream 1, substreams 1 and 2 may receive and decode the
symbols 0-9 and 22-31 across segments 212A-B and segments
212E-F.
[0046] In some embodiments, the above-described "pattern vector"
defines the layout of the numbering system as well as the segment
pattern used to allocate segments (including substreams and
streams) to symbol numbers in a given time diversity interval
(TDI). Moreover, the segment pattern may be used to compactly
define the allocation to the given substream in the TDI. Although
the above example provides a case of the pattern vector having a
cycle of 4 frames and the segment pattern having a cycle (or
period) of 4 frames, this is only exemplary since the segment
pattern may have a cycle that is any multiple of the pattern vector
(e.g., 8, 12, etc.). Moreover, in some embodiments, the segment
pattern may have a cycle that is an not an integer multiple (e.g.,
1/2, etc) of the pattern vector's length.
[0047] FIG. 3 depicts the time diversity interval 210A depicted in
FIG. 2. However, FIG. 3 depicts the numbering system assigned with
a pattern vector of (8, 6, 0). For example, OFDMA frame 216A
includes an MBS region 330A including symbol numbers 0-7, i.e., a
width of 8 OFDMA symbols. OFDMA frame 216B includes an MBS region
330B including symbol numbers 8-13, i.e., a width of 6 OFDMA
symbols, while OFDMA frame 216C does not include an MBS region,
which corresponds to a width of zero (0). The pattern vector (also
referred to as "pattern") would repeat in subsequent OFDMA frames
and thus MBS regions, as depicted at FIG. 3.
[0048] FIG. 4 depicts a macrodiversity system 400 including a
macrodiversity controller 420, base stations 110A-B, and client
stations 114A-B. Macrodiversity controller 420 further includes a
numbering module 422 configured to number OFDMA symbols and provide
a pattern vector to client stations, as described further below
with respect to process 500 of FIG. 5. Client stations 114A-B
further include numbering modules 425A-B to use the numbering
system and pattern vector as described further below with respect
to process 600 at FIG. 6. The macrodiversity controller 420 and, in
particular, numbering module 422 assign, based on the pattern
vector, the symbol numbers to the OFDMA symbols of the MBS regions.
In some implementations, numbering module 422 provides the pattern
vector so that the pattern vector can be included in a management
message (e.g., an MBS map message or like management message),
which may be transmitted to the client station as content in one or
more of the MBS regions.
[0049] In some implementations, the macrodiversity controller 420
receives packets 205 including streams and substreams of content
and inserts the packets 205 (as well as management messages, such
as an MBS map message including the pattern vector) into one or
more of the MBS regions 230A-C. The macrodiversity controller 420
provides the MBS regions 230A-C and schedules the MBS regions
230A-C for transmission at base stations 110A and 110B to achieve
macrodiversity. To achieve macrodiversity, the macrodiversity
controller 420 schedules the transmissions of the MBS regions
230A-C at base stations 110A and 110B, such that the transmissions
are synchronous with respect to the same OFDMA frames (or MBS
regions) being transmitted at about the same frequency, using about
the same waveform (e.g., same modulation and coding scheme), and
using about the same framing parameters (e.g., number of symbols in
the OFDMA frame, length of OFDMA symbols, cyclic prefix, and the
like). Each of the base stations 110A and 110B inserts MBS regions
230A-C into corresponding OFDMA frames 216A, B, and D, and then
transmits (per the schedule determined by the macrodiversity
controller) the OFDMA frames 216A-D, some of which include the MBS
regions 230A-C, to client stations 114A-B. Although the MBS regions
230A-C are typically transmitted using macrodiversity, other
portions of the OFDMA frames may be transmitted in a
non-macrodiversity transmission. For example, each base station may
transmit unique data using individual modulation and coding schemes
in the portions of the OFDMA frame other than the MBS regions.
Moreover, in some implementations, macrodiversity is not used at
one or more of the base stations.
[0050] At the client stations, such as client stations 114A-B,
macrodiversity provides a so-called "macrodiversity gain" by
combining the synchronous broadcast from base stations 110A and
110B. In some implementations, macrodiversity provides enhanced
SINR (signal to interference-plus-noise ratio) at the client
station, when compared to a non-macrodiversity transmission.
Moreover, the client stations 114A-B and, in particular, numbering
modules 425A-B thus use the pattern vector received from the
macrodiversity controller (and/or numbering module 422) to
determine how to access streams and substreams carried in MBS
regions 230A-C. When the pattern vector is included in an MBS
region, the pattern vector is more likely to be received and
decoded as a result of the macrodiversity gain, when compared to
inserting the pattern vector in a non-macrodiversity region of the
transmission, such as in the frame control header (FCH), downlink
map (DL-MAP), or unicast downlink region.
[0051] FIG. 5 depicts a process 500 for assigning a numbering
system to regions of a frame (e.g., assigning a consecutive
numbering system to the OFDMA symbols of the MBS regions). The
description of process 500 will refer to FIGS. 2-4 as well.
[0052] At 510, a numbering system may be assigned, based on a
pattern vector, to a group of OFDMA symbols of MBS regions across a
time diversity interval. At the numbering module 422 of the
macrodiversity controller 420, the pattern vector may be used to
determine the widths of the MBS regions. Referring to FIG. 3, given
a starting location of a time diversity interval 210A and a pattern
vector of (8, 6, 0), the first OFDMA frame 216A would include an
MBS region 330A having a width of 8 OFDMA symbols, enabling a
numbering of the symbols from 0-7. The next MBS region 330B would
have a width of 6 OFDMA symbols, enabling a numbering of 8-13, and
OFDMA frame 216C would have a width of zero OFDMA symbols, enabling
no symbols in that frame to be numbered. As additional content is
received via packets 205, numbering module 422 can continue to
consecutively number the OFDMA symbols of the MBS regions using the
pattern vector, such as the pattern vector (8, 6, 0) depicted at
FIG. 3.
[0053] At 520, the numbered symbols are assigned, by numbering
module 422, to segments. Referring to FIG. 2, the symbol numbers
0-5 are assigned to segment 212A, the symbol numbers 6-9 are
assigned to segment 212B, and so forth. By assigning the symbol
numbers to segments, the streams and substreams included within
segments are also assigned to symbol numbers. For example, symbol
numbers 0-9 carry segments 212A and 212B, which include the packets
of stream 1 including substreams 1 and 2. Moreover, FIG. 2 depicts
that symbol numbers 0-9 are broadcast as a burst (or time slice).
As such, a client station interested in accessing only stream 1
including substreams 1 and 2, can receive and decode symbol numbers
0-9 in segments 212A-B and then resume receiving and decoding at
symbol numbers 22-31 in segments 212E-F, which may enable a power
savings at the client station by receiving and decoding only when
required (e.g., not decoding the content associated with symbol
numbers 10-21 and the like). In some implementations using
IEEE-802.16, the numbering system described herein enables a
downlink data burst (e.g., a time slice) to span more than one MBS
region.
[0054] At 530, the pattern vector is provided by the macrodiversity
controller (and/or the numbering module 422) to a client station,
such as client station 114A, to enable the client station to access
segments comprising streams and substreams of packets. The pattern
vector may be included within management messages transmitted from
the macrodiversity controller 420 to the client station. For
example, numbering module 422 may include the pattern vector in a
management message sent to the client station (e.g., as a
management message inserted into an MBS region, such as in an MBS
map message). Moreover, the base station may provide segment
information (e.g., information describing the symbol numbers
assigned to each of the segments, including associated streams and
substreams).
[0055] FIG. 6 depicts a process 600 for using the numbering system
at a client station. The description of process 600 will refer to
FIGS. 2-4 as well.
[0056] At 605, a pattern vector is received at a client station.
For example, client station 114A and, in particular, numbering
module 425A, may receive a management message including the pattern
vector. The management message may be an IEEE 802.16 MBS map
included within one of the MBS regions, although the pattern vector
may be included in other management messages sent from the base
station to the client station.
[0057] At 610, the pattern vector may be used to determine the
symbol number starting a segment. For example, given the pattern
vector (10, 6, 0, 6) for example, numbering module 425A can
identify the symbol numbers assigned to MBS regions. Moreover, the
client station 114A (and/or numbering module 425A) may receive
segment information and the assigned symbol numbers (and thus the
location of the segments). Referring to the example of FIG. 2, this
segment information may for example indicate a starting symbol
number of a segment (e.g., symbol number 14) and a segment length
(e.g., an ending symbol number 21). Given the pattern vector (10,
6, 0, 6) for example, the symbol numbers 0-9 can be identified as
being assigned to MBS region 230A and the segment information may
indicate that segment 212A starts at symbol number zero and ends at
symbol number 5. The numbering module 425A of client station 114A
can then locate the start of segment 212A. The location of other
segments can be identified in a similar manner.
[0058] At 620, the client station then receives a stream of packets
at a segment starting at the symbol number determined at 610. For
example, the numbering module 425A may determine that symbol number
0 of FIG. 2 is the beginning of segment 212A and that segment 212A
ends at symbol number 5. The client station thus processes the
OFDMA symbols assigned to symbol numbers 0-5 in segment 212A to
receive and decode the OFDMA symbols into packets. The packets may
provide, for example, a digital video broadcast for presentation at
the client station. The client station may also receive a stream of
packets from other segments in a similar manner (e.g., symbol 6 is
the start of segment 212B, symbol 10 is the start of segment 212C,
and so forth).
[0059] The above example locating segment 212A is a relatively
straight forward case. However, numbering modules 425A-B may each
determine, using for example Equations 1-8 below, the location of
any symbol and which frame includes that symbol (and thus the start
of a segment).
[0060] For example, the numbering module 425A at client station
114A may determine a pattern vector based on the following:
{right arrow over (l)}=(l.sub.1,l.sub.2, . . . , l.sub.k) Equation
1,
wherein {right arrow over (l)} represents the pattern vector,
l.sub.1, l.sub.2, . . . , l.sub.k represent the elements of the
pattern vector (e.g., the first element, second element, and so
forth until the k.sup.th), and l.sub.k represents the last width in
OFDMA symbols. For example, l.sub.1 represents the width in OFDMA
symbols of the first MBS region, l.sub.2 represents the width in
OFDMA symbols of the second MBS region, and l.sub.k represents the
width in OFDMA symbols of the k.sup.th MBS region.
[0061] To determine the location of a symbol number, D, given the
pattern vector, the numbering module 425A at client station 114A
may determine another vector, {right arrow over (L)}, based on the
following:
{right arrow over (L)}=(L.sub.1,L.sub.2, . . . , L.sub.k) Equation
2,
wherein each of the elements of the vector {right arrow over (L)}
is determined based on the following equation:
L.sub.i=.SIGMA..sub.j=1.sup.il.sub.j Equation 3,
wherein j is an index that varies from 1 to the value of i, and i
is the element being determined in vector, {right arrow over (L)}.
To illustrate with a numerical example, given the pattern vector
{right arrow over (l)} (8, 6, 0) depicted at FIG. 3, the vector
{right arrow over (L)} is equal to (8, 14, 14).
[0062] Next, the numbering module 425A at client station 114A may
determine the value p based on the following equation:
p = D L k , Equation 4 ##EQU00001##
wherein L.sub.k is the last element of the vector {right arrow over
(L)}, D is the particular symbol number being located, and the
function [ ] represents that the quotient is rounded down to the
nearest integer. Continuing with the above numerical example, given
the symbol number to be located D is 31 (see, e.g., symbol number
31 at FIG. 3), the value of p is equal to 2
( e . g . , 31 14 ) . ##EQU00002##
[0063] Next, the numbering module 425A at client station 114A may
determine the smallest values of the variables m and L.sub.m, such
that the values satisfy the following inequalities:
l.ltoreq.m<k, such that D<pL.sub.k+L.sub.m Equations 5 and
6.
[0064] Continuing with the numerical example, m is equal to 1, so
that L.sub.m=L.sub.1=8 (e.g., 31<2(14)+8). Hence, the numbering
module 425A at client station 114A determines that the symbol
number D is located at the following frame:
(pk+m) Equation 7,
wherein the symbol number D is at the (pk+m).sup.th OFDMA frame of
the time diversity interval. Continuing with the previous numerical
example (which is also depicted at FIG. 3), symbol D (i.e., the
31.sup.st symbol in this example) is in the 7.sup.th OFDMA frame
(e.g., based on Equation 7, (2.times.3)=1).
[0065] The numbering module 425A may also determine the location of
symbol D within the (pk+m).sup.th OFDMA frame based on the
following:
(D-pL.sub.k-L.sub.m-1+1) Equation 8.
[0066] Returning to the previous example, the 31.sup.st symbol
(i.e., D=31), is located in the 7.sup.th frame as the 4.sup.th
OFDMA symbol within the MBS region in that frame, which is
consistent with FIG. 3. Given the pattern vector, the location of
any symbol D can be determined (and thus the start of a segment) by
numbering modules 425A-B using, for example, Equations 1-8
above.
[0067] The subject matter described herein may be embodied in
systems, apparatus, methods, and/or articles depending on the
desired configuration. In particular, various implementations of
the subject matter described (e.g., components of client stations
114A-B, base stations 110A-B, macrodiversity controller 420,
numbering modules 425A-B, and numbering module 422) may be realized
in digital electronic circuitry, integrated circuitry, specially
designed ASICs (application specific integrated circuits), computer
hardware, firmware, software, and/or combinations thereof. These
various implementations may include implementation in one or more
computer programs that are executable and/or interpretable on a
programmable system including at least one programmable processor,
which may be special or general purpose, coupled to receive data
and instructions from, and to transmit data and instructions to, a
storage system, at least one input device, and at least one output
device. For example, the components client stations 114A-B, base
stations 110A-B, macrodiversity controller 420, numbering modules
425A-B, numbering module 422, and aspects of processes 500 and 600
may be realized in digital electronic circuitry, integrated
circuitry, specially designed ASICs (application specific
integrated circuits), computer hardware, firmware, software
(including computer programs), and/or combinations thereof. The
numbering module 422 and numbering modules 425A-B are only
exemplary components, as the functionality of each of the modules
may be implemented as a single module or distributed among a
plurality of components of system 400 and/or system 100.
[0068] These computer programs (also known as programs, software,
software applications, applications, components, or code) include
machine instructions for a programmable processor, and may be
implemented in a high-level procedural and/or object-oriented
programming language, and/or in assembly/machine language. As used
herein, the term "machine-readable medium" refers to any computer
program product, computer-readable medium, apparatus and/or device
(e.g., magnetic discs, optical disks, memory, Programmable Logic
Devices (PLDs)) used to provide machine instructions and/or data to
a programmable processor, including a machine-readable medium that
receives machine instructions as a machine-readable signal.
Similarly, systems are also described herein that may include a
processor and a memory coupled to the processor. The memory may
include one or more programs that cause the processor to perform
one or more of the operations described herein.
[0069] Although a few variations have been described in detail
above, other modifications or additions are possible. In
particular, further features and/or variations may be provided in
addition to those set forth herein. For example, the
implementations described above may be directed to various
combinations and subcombinations of the disclosed features and/or
combinations and subcombinations of several further features
disclosed above. In addition, the logic flow depicted in the
accompanying figures and/or described herein does not require the
particular order shown, or sequential order, to achieve desirable
results. Other embodiments may be within the scope of the following
claims.
* * * * *