U.S. patent application number 11/043279 was filed with the patent office on 2005-11-10 for method and device for transmission and reception over a distributed media access control network.
Invention is credited to Danon, Tamar, Kupershmidt, Yefim, Zack, Rafi.
Application Number | 20050249183 11/043279 |
Document ID | / |
Family ID | 34753024 |
Filed Date | 2005-11-10 |
United States Patent
Application |
20050249183 |
Kind Code |
A1 |
Danon, Tamar ; et
al. |
November 10, 2005 |
Method and device for transmission and reception over a distributed
media access control network
Abstract
A method and device for reception and transmission using a
distributed media access control scheme. The device includes an
interface for receiving a payload including multiple information
signals; and circuitry adapted to process the payload to provide an
information frame that includes a PHY layer header, multiple
payload fragments, multiple fragmentation control fields and
multiple payload fragment check sequence fields; and further
adapted to transmit the information frame using a distributed media
access control scheme; whereas the multiple payload fragments are
associated with the multiple fragmentation control fields and with
the multiple payload fragment check sequence fields. The method
includes: receiving a payload including multiple information
signals; processing the payload to provide an information frame
that includes a PHY layer header, multiple payload fragments,
multiple fragmentation control fields and multiple payload fragment
check sequence fields; and transmitting the information frame using
a distributed media access control scheme; whereas the multiple
payload fragments are associated with the multiple fragmentation
control fields and with the multiple payload fragment check
sequence fields.
Inventors: |
Danon, Tamar; (Tel Aviv,
IL) ; Zack, Rafi; (Givat Shmuel, IL) ;
Kupershmidt, Yefim; (Or Yehuda, IL) |
Correspondence
Address: |
BLAKELY SOKOLOFF TAYLOR & ZAFMAN
12400 WILSHIRE BOULEVARD
SEVENTH FLOOR
LOS ANGELES
CA
90025-1030
US
|
Family ID: |
34753024 |
Appl. No.: |
11/043279 |
Filed: |
January 25, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11043279 |
Jan 25, 2005 |
|
|
|
PCT/IL05/00021 |
Jan 6, 2005 |
|
|
|
60535436 |
Jan 8, 2004 |
|
|
|
60535621 |
Jan 8, 2004 |
|
|
|
Current U.S.
Class: |
370/347 ;
370/473 |
Current CPC
Class: |
H04L 1/0041 20130101;
H04L 47/14 20130101; H04B 7/2628 20130101; H04W 88/04 20130101;
H04L 1/1607 20130101; H04B 1/7163 20130101; H04W 28/065 20130101;
H04W 72/0446 20130101; H04B 2201/70702 20130101; H04L 45/00
20130101; H04W 28/14 20130101; H04W 72/1263 20130101; H04L 45/16
20130101; H04W 72/1242 20130101; H04W 74/08 20130101; H04W 28/10
20130101 |
Class at
Publication: |
370/347 ;
370/473 |
International
Class: |
H04B 007/212 |
Claims
We claim:
1. A method for transmission over a network, the method comprises:
receiving at least multiple information signals; processing the
multiple information signals to provide an information frame that
comprises a PHY layer header, multiple payload fragments, multiple
fragmentation control fields and multiple payload fragment check
sequence fields; and transmitting the information frame while
utilizing a distributed media access control scheme; whereas the
multiple payload fragments are associated with the multiple
fragmentation control fields and with the multiple payload fragment
check sequence fields.
2. The method of claim 1 whereas each payload fragment is
associated with a fragmentation control field and with a payload
fragment check sequence field.
3. The method of claim 1 whereas a payload fragment is
substantially smaller than the payload.
4. The method of claim 1 whereas the stage of processing further
comprises providing a MAC layer header that includes fragmentation
information representative of a structure of the information
frame.
5. The method of claim 1 whereas most payload fragments are of the
same length.
6. The method of claim 1 whereas the payload further comprises an
aggregate header.
7. The method of claim 1 wherein the network is a ultra wide band
access network.
8. A device, comprising: an interface for receiving at least
multiple information signals ; and circuitry adapted to process the
at least multiple information signals to provide an information
frame that comprises a PHY layer header, multiple payload
fragments, multiple fragmentation control fields and multiple
payload fragment check sequence fields; whereas the multiple
payload fragments are associated with the multiple fragmentation
control fields and with the multiple payload fragment check
sequence fields; and whereas the circuitry is further adapted to
transmit the information frame using a distributed media access
control scheme.
9. The device of claim 8 whereas the transmission occurs over an
ultra wide band wireless medium.
10. The device of claim 8 whereas each payload fragment is
associated with a fragmentation control field and with a payload
fragment check sequence field.
11. The device of claim 8 whereas a payload fragment is
substantially smaller than the payload.
12. The device of claim 8 whereas the circuitry is adapted to
provide a MAC layer header that includes fragmentation information
representative of a structure of the information frame.
13. The device of claim 8 whereas the payload further comprises an
aggregate header.
14. A method for reception, the method comprises: receiving an
information frame that was transmitted utilizing a distributed
media access control scheme, the information frame comprises a PHY
layer header, multiple payload fragments, multiple fragmentation
control fields and multiple payload fragment check sequence fields;
whereas the multiple payload fragments are associated with the
multiple fragmentation control fields and with the multiple payload
fragment check sequence fields; and processing the information
frame to provide a payload that comprises multiple information
signals.
15. The method of claim 14 whereas each payload fragment is
associated with a fragmentation control field and with a payload
fragment check sequence field.
16. The method of claim 14 whereas a payload fragment is
substantially smaller than the payload.
17. The method of claim 14 whereas the payload further comprises an
aggregate header.
18. A device, comprising: a receiver interface adapted to receive
an information frame that was transmitted using a distributed media
access control scheme, the information frame includes a PHY layer
header, multiple payload fragments, multiple fragmentation control
fields and multiple payload fragment check sequence fields; whereas
the multiple payload fragments are associated with the multiple
fragmentation control fields and with the multiple payload fragment
check sequence fields; and circuitry adapted to process the
information frame to provide a payload that comprises multiple
information signals.
19. The device of claim 18 whereas each payload fragment is
associated with a fragmentation control field and with a payload
fragment check sequence field.
20. The device of claim 18 whereas a payload fragment is
substantially smaller than the payload.
21. The device of claim 18 whereas the payload further comprises an
aggregate header.
Description
RELATED APPLICATIONS
[0001] The present patent application is a continuation application
of International Application No. PCT/IL05/000021 filed Jan. 6,
2005, which claims priority benefit from United States Provisional
Application No. 60/535,436 filed Jan. 8, 2004 and United States
Provisional Application No. 60/535,621 filed Jan. 8, 2004, the
contents of which are incorporated herein by reference.
[0002] This application is related to the following
applications:
[0003] 1. METHOD AND DEVICES FOR MULTICASTING INFORMATION OVER A
NETWORK THAT APPLIED A DISTRIBUTED MEDIA ACCESS CONTROL SCHEME,
application Ser. No. ______, filed Jan. 25, 2005.
[0004] 2. METHODS AND DEVICES FOR EXPANDING THE RANGE OF A NETWORK,
application Ser. No. ______, filed Jan. 25, 2005.
[0005] 3. METHOD AND SYSTEM FOR OPERATING MULTIPLE DEPENDENT
NETWORKS, application Ser. No. ______, filed Jan. 25, 2005.
[0006] 4. A DEVICE AND METHOD FOR MAPPING INFORMATION STREAMS To
MaC LAYER QUEUES, application Ser. No. ______, filed Jan. 25,
2005.
[0007] 5. ULTRA WIDE BAND WIRELESS MEDIUM ACCESS CONTROL METHOD AND
A DEVICE FOR APPLYING AN ULTRA WIDE BAND WIRELESS MEDIUM ACCESS
CONTROL SCHEME, application Ser. No. ______, filed Jan. 25,
2005.
[0008] 1. Field of the Invention
[0009] The invention relates to method and devices for transmission
and reception over distributed media access control networks and
especially over ultra wide band wireless networks utilizing a
distributed media access control scheme.
[0010] 2. Background of the Invention
[0011] Recent developments in telecommunication and semiconductor
technologies facilitate the transfer of growing amounts of
information over wireless networks.
[0012] Short-range ultra wide band wireless networks are being
developed in order to allow wireless transmission of vast amounts
of information between various devices.
[0013] Some of the short-range ultra wide band wireless networks
are characterized by a distributed architecture in which devices
exchange information without being controlled by a central host or
a base station.
[0014] FIG. 1 is a schematic illustration of two ultra wide band
wireless networks (also referred to as personal access networks) 10
and 20, each including multiple devices that wirelessly communicate
with each other. First network 10 includes first till third devices
A-C 11-13 and the second network 20 includes forth till sixth
devices D-F 24-26.
[0015] Each of the ultra wide band wireless networks uses time
division multiple access (TDMA) techniques in order to allow its
devices to share a single channel.
[0016] FIG. 2 illustrates a typical TDMA frame 30. TDMA frame 30
includes multiple time-slots, such as beacon slots 14 and media
access slots. The media access slots include distributed
reservation period (DPR) slots 36 and prioritized contention access
(PCA) slots 38. PCA slots are also referred to as PCA periods. DRP
slots are also referred to as DRP periods.
[0017] The beacon slots are used to synchronize devices to the TDMA
frame 30. A typical beacon frame includes information that
identifies the transmitting device. It also may include timing
information representative of the start time of the TDMA frame
30.
[0018] The DRP slots 36 are coordinated between devices that belong
to the same network and allow devices to reserve these slots in
advance. During the PCA slots 38 devices that belong to the network
compete for access based upon their transmission priority. It is
noted that the allocation of media access time slots is dynamic and
can change from one TDMA frame to another.
[0019] Typically, transmissions from devices during PCA slots are
assigned by applying a carrier sense multiple access with collision
avoidance (CSMA/CA) scheme If a device requests to transmit over a
wireless medium it has to check if the wireless medium is idle. If
the wireless medium is idle, the device has to wait a random
backoff period. This random backoff time is selected from a
contention window that has a length that is related to the priority
of the device. For higher-priority devices the contention window is
shorter.
[0020] The transmission process is usually quite complex and
includes many operations such as but not limited to forward
correction encoding, interleaving, modulating and the like. A
receiver must reverse the procedures applied by the
transmitter.
[0021] Various techniques are applied in order to increase the
reliability of wireless telecommunications. A first technique
includes sending acknowledgement messages to indicate a reception
of a certain information frame when performing point-to-point
transmission. These acknowledgement messages can be sent per frame
(Immediate ACK scheme) or per a group of frames (Burst ACK scheme).
The former decreases the communication channel utilization but
reduces communication error penalty. Burst ACK scheme is capable of
keeping high throughput at the price of higher implementation
complexity and higher memory requirements for a device. The
acknowledgement transmission techniques (Imm-ACK and B-ACK) are not
applied when performing multicast or broadcast transmission over
ultra wide band wireless networks.
[0022] In some networks that include a central station and various
clients or a master station and multiple slave stations various
acknowledgment schemes were applied. The following U.S. patent,
U.S. patent applications and PCT patent application, all being
incorporated herein by reference, provide an example of some prior
art methods and systems: U.S. patent application 2001/0051529 of
Davies titled "Radio system and apparatus for, and method of,
multicast communication"; U.S. Pat. No. 6,122,483 of Lo et al.
titled "Method and apparatus for multicast messaging in a public
satellite network"; U.S. patent application 2003/0145102 of
Keller-Tuberg, titled "Facilitating improved reliability of
internet group management protocol through the use of
acknowledgment massages"; and PCT patent application WO2004/084488
of Lynch et al, titled "Method and apparatus for reliable
multicast".
[0023] Another technique involves introducing forward error
correction encoding, such as convolutional encoding, that puts
redundancies in the information that can be used to correct a
limited amount of errors. Yet a further technique included only
error detection, and not correction.
[0024] It is noted that in some applications (such as but not
limited to streaming video, sound, and the like) the performance
and the user experience deteriorate significantly when the
non-acknowledgement schemes are used with nominal channel
conditions (.about.1-8% Packet Error Ratio). Also, using
acknowledge schemes in layers above the MAC layer (such as TCP/IP
layers) increase significantly the latency and memory requirements
and in some cases make the application impractical if not
impossible from implementation standpoint.
[0025] There is a need to increase the reliability of ultra wide
band transmission while keeping the throughput high and
implementation requirements overhead low, reducing transmission or
reception error penalty.
SUMMARY OF THE INVENTION
[0026] A device for transmission. The device includes: (i) an
interface for receiving at least multiple information signals; and
(ii) circuitry adapted to process the at least multiple information
signals to provide an information frame that includes a PHY layer
header, multiple payload fragments, multiple fragmentation control
fields and multiple payload fragment check sequence fields. The
circuitry is further adapted to transmit the information frame over
a network that utilized a distributed media access control scheme.
The multiple payload fragments are associated with the multiple
fragmentation control fields and with the multiple payload fragment
check sequence fields.
[0027] A method for transmission includes: (i) receiving at least
multiple information signals; (ii) processing the at least
information signals to provide an information frame that includes a
PHY layer header, multiple payload fragments, multiple
fragmentation control fields and multiple payload fragment check
sequence fields; and (iii) transmitting the information frame over
a network that utilizes a distributed media access control scheme;
whereas the multiple payload fragments are associated with the
multiple fragmentation control fields and with the multiple payload
fragment check sequence fields.
[0028] A method for reception, the method includes: (i) receiving,
an information frame that was transmitted over a network that
utilizes a distributed media access control scheme, the information
frame includes a PHY layer header, multiple payload fragments,
multiple fragmentation control fields and multiple payload fragment
check sequence fields; whereas the multiple payload fragments are
associated with the multiple fragmentation control fields and with
the multiple payload fragment check sequence fields; and (ii)
processing the information frame to provide a payload that
comprises multiple information signals.
DESCRIPTION OF THE DRAWINGS
[0029] The present invention will be understood and appreciated
more fully from the following detailed description taken in
conjunction with the drawings in which:
[0030] FIG. 1 is a schematic illustration of two networks (also
referred to as personal access networks), each including multiple
devices that wirelessly communicate with each other;
[0031] FIG. 2 illustrates a typical TDMA frame;
[0032] FIG. 3 illustrates a proposed MBOA information frame;
[0033] FIGS. 4a-4b illustrate a device capable of wireless
transmission, and some of its components, according to an
embodiment of the invention;.
[0034] FIGS. 5 and 9 illustrate an information frame, according to
an embodiment of the invention;
[0035] FIG. 6 illustrates the throughput achieved when using
different information frames;
[0036] FIG. 7 is a flow chart that illustrates a method for
transmission, according to an embodiment of the invention; and
[0037] FIG. 8 is a flow chart that illustrates a method for
reception, according to an embodiment of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0038] The following description related to wireless ultra wide
band networks that utilize a distributed media access control
scheme. In these networks there is no central media access
controller, but rather various devices of the network participate
in determining how to share a common wireless medium. It is noted
that according to various embodiments of the invention the
disclosed methods and devices can be applied in networks that
utilize a distributed media access control scheme but differ from
ultra wide band wireless networks.
[0039] Various operations such as transmissions utilize the
distributed media access control scheme in the sense that the
access to a shared medium is governed by a distributed media access
control scheme.
[0040] MBOA is a standard that is being developed by various
vendors in the field of ultra wide band wireless communication. A
MBOA transmitter has a PHY layer that is capable of performing
multiple operations, such as but not limited to convolutional
encoding, bit padding, time frequency code (TFC) interleaving,
Quadrature Phase Shift Key (QPSK) modulation and Orthogonal
Frequency Division Multiplexing (OFDM).
[0041] A typical transmitter includes a convolutional encoder, an
interleaver and a OFDM modulator. An information sequence enters a
convolutional encoder that adds redundant bits, the sequence is
then interleaved in order to cope with burst errors, and then OFDM
modulated. Said modulation includes mapping multiple signals to
multiple narrowband subcarriers and performing inverse Fourier
transform to provide a sequence of OFDM symbols.
[0042] FIG. 3 illustrates a proposed MBOA information frame 100.
The information frame 100 includes a physical layer convergence
procedure (PLCP) preamble 112, a PHY layer header 114, a MAC layer
header 116, a header check sequence field (HCS) 118, header tail
bits 120, header pad bits 121, payload 122, a frame check sequence
field (FCS) 124, frame tail bits 126 and pad bits 128.
[0043] The information frame 100 includes MAC layer fields such as
fields 116, 118, 122 and 124. Information frame 100 also includes
various PHY layer fields, such as fields 112, 114, 120, 121, 126
and 128. The payload 122 usually includes one or more MAC layer
frames (also known as MSDU or MCDU) or frames of a upper
communication protocol layer, such as an application layer.
Typically information frame 100 includes a single upper layer
frame.
[0044] The PLCP preamble 112 includes a packet and frame
synchronization sequences that are followed by a channel estimation
sequence. The PLCP preamble assists the receiver, among other
things, to estimate the properties of the wireless medium. MBOA
proposes two possible PLCP preambles--a short PLCP preamble and a
long PLCP preamble. The long PLCP preamble is used at low bit
rates. At high bit rates a first frame includes the long PLCP
preamble while the remaining frames include the short PLCP
preamble.
[0045] The PHY layer header 114 includes information about the type
of modulation, the coding rate and the spreading factor used during
the transmission of the information, the length of the frame
payload and scrambling data information.
[0046] MAC layer header 116 includes a frame control field, source
and destination identification fields, sequence control fields 117
and duration/access method fields.
[0047] The header tail bits 120 as well as the frame tail bits 126
are set to zero, thus allowing a convolutional encoder within the
receiver to return to a "zero state" and improve its error
probability. The header tail bits 120 (the frame tail bits 126) are
followed by header pad bits 121 (frame pad bits 128) in order to
align the information stream on an OFDM interleaver boundaries.
[0048] The payload is usually between one byte and 4096 bytes long.
When a transmission or reception error occurs the whole frame is
re-transmitted.
[0049] The mentioned below information frame is transmitted by a
device that is a part of a wideband wireless network and has a
communication protocol stack that includes at least a PHY layer and
a MAC layer. The MAC layer of such devices controls the access to
ultra wide band wireless medium and is referred to ultra wide band
wireless medium access control.
[0050] Examples of devices that have a PHY layer are illustrated in
the following U.S. patent applications, all being incorporated
herein by reference: U.S. patent application Ser. No. 10/389789
filed on Mar. 10, 2003 and U.S. patent application Ser. No.
10/603,372 filed on Jun. 25 2003.
[0051] The device can include various components that are arranged
in multiple layers. A first configuration includes a frame
convergence sub-layer, a MAC layer, a PHY layer as well as MAC SAP,
PHY SAP, frame convergence sub-layer SAP and a device management
entity can also be utilized. Another configuration is described at
FIGS. 4a and 4b.
[0052] Wisair Inc. of Tel Aviv Israel manufactures a chip set that
includes a Radio Frequency PHY layer chip and a Base-Band PHY layer
chip. These chips can be connected in one end to a RF antenna and
on the other hand be connected or may include a MAC layer
circuitry.
[0053] FIG. 4a illustrates a device 60 that is capable of wireless
transmission, according to an embodiment of the invention.
[0054] Device 60 includes antenna 61 that is connected to a RF chip
62. RF chip 62 is connected to a MAC/PHY layers chip 63 that
includes a PHY layer block 63 and a MAC layer block 64. The MAC/PHY
layers chip 63 is connected to an application entity 66 that
provides it with information to be eventually transmitted (TX) and
also provides the application 66 with information received (RX) by
antenna 61 and processed by PHY and MAC layers blocks 68 and 69 of
FIG. 4b.
[0055] Typically, the MAC layer block 64 controls the PHY layer
block using a PHY status and control interface. The MAC and PHY
layers exchange information (denoted TX and RX) using PHY-MAC
interface 90. The RF chip 62 provides to the PHY layer block 63
received information that is conveniently down-converted to base
band frequency. The RF chip 62 receives from the PHY layer block 63
information to be transmitted as well as RF control signals. The
application 66 is connected to the MAC/PHY layers chip 63 by a high
speed I/O interface.
[0056] FIG. 4b illustrates various hardware and software components
of the MAC/PHY layers chip 63, according to an embodiment of the
invention.
[0057] The Upper Layer IF block 64 of the MAC/PHY layers chip 63
includes hardware components (collectively denoted 69) and software
components (collectively denoted 68). These components includes
interfaces to the PHY layer (MAC- PHY interface 90) and to the
application (or higher layer components).
[0058] The hardware components 69 includes configuration and status
registers 81, Direct Memory Access controller and list processor
82, First In First Out (FIFO) stacks 83 and frame validation and
filtering components 84, DRP and PCA slots schedulers 85, ACK
processors 86, and MAC-PHY internal interface 87.
[0059] The software components 68 includes a management module 72,
transmit module 73, receive module 74m hardware adaptation layer
75, DMA drivers 76, MAC layer management entity (MLME) service
access point (SAP) 71, MACS API 70 and the like.
[0060] These software and hardware components are capable of
performing various operations and provide various services such as:
providing an interface to various layers, filtering and routing of
specific application packets sent to MAC data queues or provided by
these queues, performing information and/or frame processing, and
the like.
[0061] The routing can be responsive to various parameters such as
the destinations of the packets, the Quality of Service
characteristics associated with the packets, and the like.
[0062] The processing of information along a transmission path may
include: forming the MAC packet itself, including MAC header
formation, aggregation of packets into a bigger PHY PDU for better
efficiency, fragmentation of packets for better error rate
performance, PHY rate adaptation, implementation of
Acknowledgements policies, and the like.
[0063] The processing of information along a reception path may
include de-aggregation and/or de-fragmentation of incoming packets,
implementation of acknowledgment and the like.
[0064] The hardware components are capable of transferring data
between MAC software queues and MAC hardware (both TX and RX),
scheduling of beacons slots, scheduling of DRP and PCA access
slots, validation and filtering (according to destination address
of incoming frames, encryption/decryption operations, low-level
acknowledgement processing (both in the TX path and in the RX
path).
[0065] Device 60 can be a simple device or even a complex device
such as but not limited to a multimedia server that is adapted to
transmit information frames of different types to multiple devices.
It can, for example transmit Streaming data, like voice, Video,
Game applications, etc.) data files during DRP slots, and while PCA
slots transmits video over IP frames download MP3 files, download
MPEG-2 files, and stream or download MPEG-4 streams.
[0066] It is noted that device 60 is capable of receiving as well
as transmitting information. Thus device 60 includes a receiver
that includes multiple software and hardware components that are
capable of substantially reversing the operation of the device
transmitter portions.
[0067] The receiver includes a receiver interface (such as antenna
and RF chip) adapted to receive an information frame that was
transmitted over an ultra wide band wireless medium, the
information frame includes a PHY layer header, multiple payload
fragments, multiple fragmentation control fields and multiple
payload fragment check sequence fields; whereas the multiple
payload fragments are associated with the multiple fragmentation
control fields and with the multiple payload fragment check
sequence fields. That receiver also includes circuitry (such as MAC
layer components) for processing the information frame to provide a
payload that comprises multiple information signals.
[0068] FIG. 5 illustrates information frame 200, according to an
embodiment of the invention.
[0069] The information frame 200 includes a PHY layer preamble,
such as PLCP preamble 112, a PHY layer header 114, a modified MAC
layer header 116', HCS 118, header tail bits 120, header pad bits
121. These are followed by a sequence 210 of fragmentation control
fields 212(1)-212(K), payload fragments 214(1)-214(K) and payload
fragment check sequence field 216(1)-216(K). Whereas K is a
positive integer representing the amount of payload fragments per
information frame 200 and whereas each payload fragment is preceded
by a corresponding fragmentation control field and is followed by a
payload fragment check sequence field. Sequence 210 is followed by
a frame check sequence field (FCS) 124, frame tail bits 126 and pad
bits 128.
[0070] Most of the fragments, except the last fragment have the
same size, thus information about their size is not transmitted.
This is not necessarily so.
[0071] It is noted that the size of the fragment can be
pre-negotiated or otherwise defined and transmitted to the
receiver. Alternatively, part MAC header, like the Sequence Control
field of the MAC header can be used to notify the size of the
fragment in a particular aggregated frame.
[0072] It is noted that the information frame can include a long
PLCP preamble, or a short PCLP preamble, according, for example to
the bit rate and the order of an information frame within a series
of information frames.
[0073] The inventors found that by using relatively short payload
fragments and associating a payload fragment check sequence field
and a fragmentation control field the penalty of errors is
dramatically reduced from the size of a PHY frame to the size of a
payload fragment.
[0074] FIG. 6 illustrates the throughput achieved when using
different information frames.
[0075] The X-axis represents the PHY layer data rate. The Y-axis
represents the effective throughput at Million bits per second. The
effective throughput is the rate of information payload.
[0076] The following curves were generated by simulating a
transmission sequence of a first information frame that includes a
long PCLP preamble, followed by five information frames that
include a short PCLP preamble.
[0077] It is noted that these graphs were simulated under the
assumption that no re-transmissions are required. It is noted that
the low overhead associated with this scheme increases
throughput.
[0078] Curve 82 illustrates the transmission of information frame
such as information frame 200, while the other curves illustrate
the transmission information frames such as information frame 100,
of various lengths.
[0079] The upper curve 81 represents the effective throughput
achieved when using information frames of four thousand bits. At a
PHY data rate of about four hundred and eighty Mbps an effective
throughput of four hundred Mbps was achieved.
[0080] The following curve 82 represents the effective throughput
achieved when using information frames of about four thousand bits
that include multiple two hundred and fifty six bit fragments. At a
PHY data rate of about four hundred and eighty Mbps an effective
throughput of three hundred and ninety Mbps was achieved.
[0081] The four lower curves 83-86 represent the effective
throughputs achieved when using information frames of two thousand,
one thousand, five hundred and two hundred and fifty bits,
accordingly. At a PHY data rate of about four hundred and eighty
Mbps effective throughputs of three hundred and fifty, two hundred
and eighty, one hundred and ninety and one hundred and ten Mbps
respectively was achieved.
[0082] FIG. 7 illustrates a method 300 for transmission, according
to an embodiment of the invention.
[0083] Method 300 starts by stage 310 of receiving at least
multiple information signals. According to an embodiment of the
invention the information signals can belong to multiple
frames.
[0084] Stage 310 is followed by stage 320 of processing the at
least multiple information signals to provide an information frame
that includes a PHY layer header, multiple payload fragments,
multiple fragmentation control fields and multiple payload fragment
check sequence fields. Conveniently, the multiple payload fragments
are associated with the multiple fragmentation control fields and
with the multiple payload fragment check sequence fields. It is
noted stage 310 does not necessarily include processing all the
received signals. It is also noted that during said processing some
signals can be modified, other signals can be deleted and the
like.
[0085] According to an embodiment of the invention stage 310
includes aggregating signals from multiple payloads and/or frames.
Conveniently, the control bits associated with each received frame
can be modified or remain unchanged. The control bits may include
MAC header bits and the like.
[0086] Conveniently, after the fragments and other parts of the
information frame are generated the processing continues to
aggregate them into an information frame. Said aggregation can also
require an alteration of the information frame header, for example
for notifying that the information frame is an aggregated
frame.
[0087] Conveniently, each payload fragments is associated with a
fragmentation control field and with a payload fragment check
sequence field.
[0088] Conveniently, a payload fragment is substantially smaller
than the payload.
[0089] According to an embodiment of the invention stage 320
further includes providing a MAC layer header that includes
fragmentation information representative of a structure of the
information frame.
[0090] Conveniently, at least most payload fragments are of the
same length. Typically, the last fragment sizes differs from the
size of other fragments.
[0091] Conveniently, the fragmentation control fields include a
payload sequence serial number and also include a fragment serial
number.
[0092] Stage 320 is followed by stage 330 of transmitting the
information frame utilizing a distributed media access control
scheme. This stage can involve transmitting over a ultra wide band
wireless medium.
[0093] FIG. 8 illustrates a method 400 for reception, according to
an embodiment of the invention.
[0094] Conveniently, a receiver that executes the stages of method
400 substantially reverses the stages applied by a transmitted
applying method 300.
[0095] Method 400 starts by stage 410 of receiving an information
frame that was transmitted over a network that applied a
distributed media access control scheme. The transmission can
involve a transmission over an ultra wide band wireless medium. The
information frame includes a PHY layer header, a MAC header with
notification of the type of frame (In-MPDU fragmented), multiple
payload fragments, multiple fragmentation control fields and
multiple payload fragment check sequence fields; whereas the
multiple payload fragments are associated with the multiple
fragmentation control fields and with the multiple payload fragment
check sequence fields.
[0096] Stage 410 is followed by stage 420 of processing the
information frame to provide a payload that includes multiple
information signals.
[0097] According to various embodiments of the invention the device
is capable of aggregating multiple MAC layer frames to a single PHY
frame. These MAC layer frames or MAC layer segments can be treated
as information frame 500 fragments.
[0098] FIG. 9 illustrates an information frame 500 that includes a
PHY layer preamble, such as PLCP preamble 112, a PHY layer header
114, a modified MAC layer header 116", HCS 118, header tail bits
120, header pad bits 121. These are followed by an aggregation
header 502, and a sequence 510 of fragmentation control (FC) fields
512(1)-512(K), payload fragments 514(1)-514(K) and payload fragment
check sequence (FCS) fields 516(1)-516(K). The FC fields can also
indicate if a certain payload fragment is the last within the PHY
frame. The last FCS field 516(K) is followed by a frame check
sequence field (FCS) 124, frame tail bits 126 and pad bits 128.
[0099] The aggregation header 502 includes the following fields:
amount of MAC layer frames 522, and for each payload fragment its
length 524(1)-524(K), and a fragmentation control fields
526(1)-526(K) indicating whether this is a fragment of a MAC layer
frame and if so whet is it's serial number. It is noted that at
least some of the payload fragments can be MAC layer frames. In
such a case the MAC layer frames are not necessarily fragmented in
order to generate the information frame 500.
[0100] It is assumed that the information frame 500 is generated in
response to a reception of one or more original frames. According
to various embodiments of the invention the information frame can
be generated in various manners. The information frame can include
the payloads of more than one original frame but can also include
portions of a single original frame. For example, the information
frame can be generated by aggregating original frames that include
their own frame check sequence protection fields. Yet for another
example, the information frames can be generated by fragmenting a
single original frame and adding various fields.
[0101] According to another embodiment of the invention the
information frame 500 does not include FCS or FC fields for each
payload fragment, and the aggregation header is altered
accordingly.
[0102] According to various embodiments of the invention the device
can dynamically determines the configuration of a transmitted
information frame in response to wireless medium quality and in
response to a quality of service associated with certain
applications. The wireless medium quality can be assessed by
monitoring transmission successes and failures (for example
monitoring acknowledge based transmissions), by performing an PHY
layer SNR estimation, and the like. The quality of service can be
represented by various parameters including, for example, packet
error rate, latency, interval between channel reservation, and the
like.
[0103] It will be apparent to those skilled in the art that the
disclosed subject matter may be modified in numerous ways and may
assume many embodiments other then the preferred form specifically
set out and described above.
[0104] Accordingly, the above disclosed subject matter is to be
considered illustrative and not restrictive, and to the maximum
extent allowed by law, it is intended by the appended claims to
cover all such modifications and other embodiments, which fall
within the true spirit and scope of the present invention.
[0105] The scope of the invention is to be determined by the
broadest permissible interpretation of the following claims and
their equivalents rather then the foregoing detailed
description.
* * * * *