`
`(12) United States Patent
`Ma et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,551,546 B2
`Jun. 23, 2009
`
`(54) DUAL-MODE SHARED OFDM
`METHODS/TRANSMITTERS, RECEIVERS
`AND SYSTEMS
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`(75) Inventors: Jianglei Ma, Kanata (CA); Wen Tong,
`Ottawa (CA); Ming Jia, Ottawa (CA);
`Peiying Zhu, Kanata (CA); Dong-Sheng
`Yu, Ottawa (CA)
`(73) Assignee: Nortel Networks Limited, St. Laurent,
`Quebec (CA)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 1348 days.
`(21) Appl. No.: 10/406,207
`(22) Filed:
`Apr. 4, 2003
`
`(*) Notice:
`
`(65)
`
`Prior Publication Data
`US 2004/OOO1429 A1
`Jan. 1, 2004
`
`Related U.S. Application Data
`(60) Provisional application No. 60/391,624, filed on Jun.
`27, 2002.
`(51) Int. Cl.
`(2006.01)
`H04 II/00
`(2006.01)
`H04B 7/26
`(2006.01)
`H04L I/02
`(52) U.S. Cl. ....................... 370/208: 370/335; 370/342;
`375/267
`(58) Field of Classification Search ................. 370/208,
`370/308, 240, 310 350: 455/277.1; 375/267,
`375/299, 346 348
`See application file for complete search history.
`
`Shapiro ...................... 382,240
`5,315,670 A *
`5, 1994
`5,345.439 A *
`9, 1994
`Marston
`... 370,320
`Pollack et al. ........
`... 370.2O3
`2, 2001
`6, 192,026 B1
`6,282, 185 B1* 8/2001
`Hakkinen et al.
`... 370,342
`6,298,092 B1 * 10/2001
`Heath et al. ................. 375,267
`(Continued)
`FOREIGN PATENT DOCUMENTS
`
`EP
`
`8, 1996
`O760560
`(Continued)
`OTHER PUBLICATIONS
`Tarokh, Vahid et al., “Space-Time Block Coding for Wireless Com
`munications: Performance Results', Mar. 1999, IEEE Journal on
`Selected Areas in Communications, vol. 17. No. 3, pp. 451-460.*
`(Continued)
`Primary Examiner Tri H Phan
`(57)
`ABSTRACT
`
`A wireless terminal and network terminal are provided for
`implementing a new uplink OFDM protocol. In the new pro
`tocol, the wireless terminal has a first transmit chain for
`generating and transmitting a low rate mode OFDM trans
`mission in a first frequency band of the OFDM band; and a
`second transmit chain for generating and transmitting a burst
`mode transmission in a second frequency band of the OFDM
`band, the first frequency band being distinct from the second
`frequency band. An access channel is provided which is over
`laid over the low rate mode transmissions of other users.
`
`76 Claims, 17 Drawing Sheets
`
`TRANSPORT
`CHANNEL
`
`MC
`SPREADING
`120
`
`ass, sland, set it
`122
`ENGER
`
`---
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`TRANSPORT
`CHANNEL
`
`MC
`SPREADING
`130
`
`HOPPING PATTERN
`
`Forsaries
`
`HOPPING PATTERN
`
`21
`
`22
`
`Mercedes EX1014
`U.S. Patent No. 10,965,512
`
`
`
`US 7,551,546 B2
`Page 2
`
`U.S. PATENT DOCUMENTS
`6,606,296 B1
`8/2003 Kokkonen ................... 370,203
`6,967,936 B1 * 1 1/2005 Laroia et al. ................ 370,329
`7,095,708 B1* 8/2006 Alamouti et al. ............ 370/208
`2002/019 1569 A1* 12/2002 Sung et al. .................. 370,335
`2004/0203395 A1 * 10, 2004 Chizhik et al. ............. 455,63.
`2004/0228267 A1* 1 1/2004 Agrawal et al. ............. 37020
`2006/0133522 A1* 6/2006 Sutivong et al. ............ 375,260
`2007/0211790 A1* 9/2007 Agrawal etal
`375,147
`
`
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`EP
`EP
`WO
`WO
`WO
`
`O786890
`1005190
`1124347
`96.37066
`98O2982
`OO797 22
`
`1, 1997
`11, 1999
`1, 2001
`5, 1996
`1, 1998
`6, 2000
`
`WO
`
`O135563
`5, 2001
`OTHER PUBLICATIONS
`Chen, Kwang-Cheng et al., “A Programmable Architecture for
`OFDM-CDMA, Nov. 1999, National Taiwan University, IEEE
`Communications Magazine, 0.163-680499, pp. 76-82.
`T. Chee, Hybric OFDM-CDMA: A Comparison of MC/DS-CDMA,
`MC-CDMA and OFCDM, Sep. 2002, Dept. of Electrical & Elec
`tronic, Adelaide University, Australia, pp. 1-10.
`Hélard, J. -F; Baudais J. -Y; Citerne, J.; Linear MMSE Detection
`Technique for MC-CDMA; Electronics Letters, Mar. 30, 2000, vol.
`36, No. 7.
`Callonnec, Denis; Pace, Daniel; Castelain, Damien; Introduction to
`SFDMA Multiple Access Networks and Their Possible Implementa
`tion in Terrestrial DVB Return Channels; IEEE, 1997, pp. 281-285.
`Naguib, Ayman, F.; Seshadri, Nambi, Calderbank, A.R., Applica
`tions of Space-Time Block Codes Interference Supression for High
`Capacity and High Data Rate Wireless Systems; IEEE, 1998, pp.
`1803-1810.
`* cited by examiner
`
`
`
`U.S. Patent
`
`Jun. 23, 2009
`
`Sheet 1 of 17
`
`US 7.551,546 B2
`
`
`
`
`
`
`
`
`OFDMA TRANSMITTER
`602
`MODE 1 POWER centrol
`618 1 8
`
`Mg, 2 RATE ONTROL
`
`---
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`-
`
`CONTROL CHANNEL
`RECEIVER
`640
`
`OFDMA TRANSMITTER
`604
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`630
`631
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`632
`63
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`616
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`SACH ASSIGNMENT AND
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`
`
`DOWNLINK
`CONTROL
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`650
`
`F.G. 1
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`U.S. Patent
`
`Jun. 23, 2009
`
`Sheet 2 of 17
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`US 7,551,546 B2
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`Jun. 23, 2009
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`Sheet 11 of 17
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`Jun. 23, 2009
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`Sheet 14 of 17
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`Jun. 23, 2009
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`Sheet 16 of 17
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`Jun. 23, 2009
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`Sheet 17 of 17
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`F.G. 15A
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`8MODE.1 PILOT
`3MODE.1 PILOT
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`BMODE DATA
`SMODE-1 DATA
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`TONES NOTUSED
`BY THIS USER
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`FIG. 15B
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`US 7,551,546 B2
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`1.
`DUAL-MODE SHARED OFDM
`METHODS/TRANSMITTERS, RECEIVERS
`AND SYSTEMS
`
`RELATED APPLICATION
`
`This application claims the benefit of prior U.S. provi
`sional application No. 60/391,624 filed Jun. 27, 2002.
`
`FIELD OF THE INVENTION
`
`This invention relates generally to wireless communica
`tions and, in particular, to an uplink air interface used in a
`wireless communication network, and more particularly to
`dual-mode shared OFDM methods/transmitters, receivers
`and systems.
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`BACKGROUND
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`nel simultaneously by respectively assigning each UE a
`unique spreading code (cover) that is orthogonal to all other
`spreading codes assigned to other UES. In other words, the
`spreading codes (cover) serve as identifiers or covers that are
`included in each of the UEs respective transmissions.
`The maximum data rate associated with uplink transmis
`sion for each of the aforementioned schemes is limited. For
`example, in 3G (i.e. third generation) cellular networks, based
`on CDMA, the multiple-access interference inherent to
`CDMA limits the data rate transmission to 2 Mbps. Moreover,
`orthogonality between the transmissions from different UEs,
`provided by the respectively assigned spreading codes, is
`difficult to maintain since the different UE's do not typically
`transmit signals synchronously. Once the orthogonality
`between the transmissions from the different UE's is com
`promised multiple-access interference is introduced, and this
`limits the maximum uplink data rate. Generally, in cellular
`networks the total multiple-access interference can be made
`up of intra-cell and inter-cell multiple-access interferences.
`European digital audio broadcast services and some
`WLAN (Wireless Local Area Network) uplink access
`schemes employ a modulation technique known as Orthogo
`nal Frequency Division Modulation (OFDM). OFDM also
`lends itself to digital television, and is being considered as a
`method of obtaining high-speed digital data transmission
`over conventional telephone lines. Advantageously, OFDM
`allows for simple processing to combat dispersive channel
`distortions and high speed data rate transmission in broadcast
`environments and single point-to-point communications. The
`drawback to OFDM is that it does not inherently provide for
`multiple-user access despite being very effective for broad
`cast and single point-to-point communications.
`OFDM has been combined with Time Division Multiplex
`ing (TDM) in Systems that require multiple-user access. For
`example, in some WLAN networks OFDM is combined with
`TDM to provide the multiple access capabilities. Namely,
`OFDM is used for uplink transmissions from one user at a
`time, with multiple-user access being arranged in a TDM
`fashion. However, this type of uplink access Scheme cannot
`effectively support cellular network deployment and mobility
`because it does not provide the quality of service and features
`required in cellular networks. In addition, these schemes do
`not support circuitry data services such as Voice.
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`A wireless network typically includes access points (e.g.
`base stations) through which User Equipment (UE) may
`access the wireless network. Each access point typically ser
`vices a Softly delineated geographic area that is known as a
`coverage area, in which UE can be used to establish a wireless
`link with the particular access point. In other words, within a
`coverage area corresponding to an access point UE can typi
`cally expect to be able to communicate (transmit and receive
`signals) wirelessly with the corresponding access point.
`In general, transmissions sent to an access point originating
`from one or more UEs are collectively known as an uplink (to
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`the access point). This is an example of a many-to-one com
`munication system in which multiple UE's must share access
`to a common wireless channel. It is difficult to manage mul
`tiple-user access to a common wireless channel since respec
`tive transmissions originating from different UE's cannot
`easily be synchronized in practical circumstances. Specifi
`cally, in a cellular network, an uplink consists of many point
`to-point transmissions that are all directed to a base station
`(access point) and that originate from respective UE's oper
`ating within a cell (coverage area) serviced by the base sta
`tion.
`Anaccess scheme, commonly known as an uplinkair inter
`face, must be specified and followed to control the way each
`UE within a wireless communication network transmits sig
`nals to access points (e.g. base stations) so that the common
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`wireless channel is effectively shared by multiple UE's. In
`cellular networks the uplink air interface must take into
`account transmissions from multiple UE's operating in the
`same cell as well as transmissions from UE's operating in
`adjacent cells. In other words, for wireless communications
`to be effective a method of dividing the common wireless
`channel, otherwise known as channelization, must be applied
`so that each UE can gain transmission access to Some portion
`of the common wireless channel for Some reasonable amount
`of time.
`Different multiple-user access schemes have been devel
`oped and employed in cellular networks for the uplink air
`interface. Examples of Such multiple-user access Schemes
`include channelization based on: i) frequency division; ii)
`time division; and iii) code division. According to Frequency
`Division Multiple Access (FDMA) the common wireless
`channel is divided into sub-channels, each of which can be
`dedicated to a single UE. On the other hand, basic Time
`Division Multiple Access (TDMA) allows multiple users to
`transmit into the entire common wireless channel one at a
`time. Code Division Multiple Access (CDMA) allows mul
`tiple UEs to transmit into the entire common wireless chan
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`SUMMARY OF THE INVENTION
`
`According to one broad aspect, the invention provides a
`wireless terminal for communicating over a shared OFDM
`band, the wireless terminal comprising: a first transmit chain
`for generating and transmitting a low rate mode OFDM trans
`mission in a first frequency band of the OFDM band; a second
`transmit chain for generating and transmitting a burst-mode
`transmission in a second frequency band of the OFDM band,
`the first frequency band being distinct from the second fre
`quency band.
`In some embodiments, the first transmit chain is power
`controlled and the second transmit chain is rate controlled.
`According to another broad aspect, the invention provides
`a wireless terminal for communicating over a shared OFDM
`band, the wireless terminal comprising: a first transmit chain
`for generating and transmitting a low rate mode OFDM trans
`mission in a first frequency band of the OFDM band; the first
`transmit chain comprises a hopping pattern generator which
`causes the first frequency band to hop around in frequency
`within a subset of the shared OFDM band allocated for low
`rate mode OFDM transmission.
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`In some embodiments, the first transmit chain comprises a
`space time encoder adapted to perform space time encoding
`to generate a signal to be transmitted during each OFDM
`transmission interval as said low rate mode OFDM transmis
`Sion.
`In some embodiments, the wireless terminal comprises a
`plurality N of transmit antennas, N>=2, wherein the first
`transmit chain comprises a space time encoder adapted to
`perform space time encoding to generate a respective STC
`sub-block comprising symbols for M sub-carriers by Ntrans
`mission intervals to be transmitted on each transmit antenna
`during each set of NOFDM transmission intervals as said low
`rate mode OFDM transmission.
`In some embodiments, the first transmit chain comprises a
`hopping pattern generator which causes the first frequency
`band to hop around infrequency within a subset of the shared
`OFDM band allocated for low rate mode OFDM transmission
`and wherein the hopping pattern generates hops with a unit of
`hopping equal to a size of the STC blocks.
`In some embodiments, each STC sub-block further com
`prises pilot symbols.
`In some embodiments, each STC sub-block further com
`prises N pilot symbols on a respective single Sub-carrier on
`each end of the STC sub-block.
`In some embodiments, the first transmit chain further com
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`prises: at least one low rate signal Source; for each low rate
`signal source, at least one distinct orthogonal spreading func
`tion adapted to generate a respective spread sequence for each
`symbol of the low rate signal source by multiplying the sym
`bol by a respective orthogonal spreading function from a set
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`of orthogonal spreading functions; a combiner for adding
`together in time the spread sequences to generate a composite
`sequence to be transmitted using said first frequency band.
`In some embodiments, the wireless terminal comprises a
`plurality N of transmit antennas, N>=2, wherein the first
`transmit chain comprises a space time encoder adapted to
`perform space time encoding to generate a respective STC
`sub-block comprising M symbols for sub-carriers by Ntrans
`mission intervals to be transmitted on each transmit antenna
`during each set of NOFDM transmission intervals as said low
`rate mode OFDM transmission, wherein the composite
`sequence is input to the space time encoder.
`In some embodiments, the set of orthogonal spreading
`functions comprises Walsh codes.
`In some embodiments, the at least one low rate signal
`Source comprises at least one of DL (downlink) channel
`condition (CQI/CLI) feedback channel; DLACK/NAK sig
`nalling channel; UL (uplink) buffer status channel; UL trans
`mit power margin channel; UL rate indicator channel; UL
`fixed data rate dedicated traffic channel.
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`In some embodiments, the wireless terminal further adapts
`to apply a variable number of Walsh code channels to the at
`least one low rate signal Source as a function of required data
`rate and/or need for protection.
`In some embodiments, the wireless terminal further com
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`prises: a control channel receiver for receiving power control
`commands in respect of the low rate mode OFDM transmis
`sions; a power control function adapted to apply transmit
`power adjustments to the low rate mode OFDM transmissions
`as a function of the power control commands.
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`In some embodiments, the wireless terminal further com
`prises a power control function adapted to: transmit an initial
`access attempt on an uplink access channel; determine a long
`term estimated downlink power measurement of a signal
`received overa downlink channel and to initially transmit said
`low rate mode OFDM transmission a transmit power deter
`mined as a function of the estimated downlink power mea
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`Surement; control channel receiver for receiving power con
`trol commands for increasing/unchanging/decreasing
`transmit power of the low rate mode OFDM transmission
`after said initial access attempt.
`In some embodiments, the wireless terminal further com
`prises: a control channel receiver for receiving channel
`assignment information allowing an identification of where
`in frequency and when in time to transmit the low rate mode
`OFDM transmissions.
`In some embodiments, the wireless terminal further com
`prises a control channel receiver for receiving channel assign
`ment information allowing an identification of where in fre
`quency and when in time to transmit the low rate mode
`OFDM transmissions wherein the channel assignment infor
`mation comprises a hopping pattern identity which allows the
`wireless terminal to perform hopping in accordance with one
`of a set of orthogonal hopping patterns.
`In some embodiments, the wireless terminal further com
`prises: a cover code generator adapted to apply a cell specific
`cover code in generating all low rate mode OFDM transmis
`sions.
`In some embodiments, the wireless terminal further com
`prises: at least one channel coder adapted to apply channel
`coding to low rate signal Sources prior to forming STC blocks.
`In some embodiments, the channel coders have a block size
`that covers several hops to achieve diversity gain and inter
`cell interference averaging.
`In some embodiments, the STC block size is NxM plus
`pilot carriers, where M is such that the block size is less than
`the coherence bandwidth.
`In some embodiments, the wireless terminal further com
`prises: an access channel transmit chain adapted to generate
`an OFDM access signal occupying a randomly selected slot
`selected from a plurality of slots comprising a frame, each slot
`comprising a predetermined block of OFDM time-frequency.
`In some embodiments, the wireless terminal further com
`prises: a control channel receiver for receiving an identity of
`a plurality of signature definitions for use in a coverage area;
`wherein the wireless terminal randomly selects one of the
`plurality of signatures and applies the signature in generating
`the access attempt.
`In some embodiments, each slot comprises four OFDM
`symbols, and there are 16 different possible signatures.
`In some embodiments, the wireless terminal further adapts
`to map the signature onto OFDM carriers based on a Peano
`Hilbert plane filling curve.
`In some embodiments, the access channel is overlaid over
`low rate mode OFDM transmissions of other wireless termi
`nals.
`In some embodiments, the wireless terminal adapts to
`function in an active and standby state, and further compris
`ing: a control channel receiver for receiving a system access
`channel assignment upon entering the standby State, the sys
`tem access channel assignment being associated with specific
`sub-carriers and OFDM symbols to be used as a system
`access channel; wherein the wireless terminal is further
`adapted to use the system access channel to transmit a pilot
`and system access requests while in the standby State.
`In some embodiments, the system access channel com
`prises two or more Sub-carriers allocated during certain peri
`odic OFDM symbols.
`In Some embodiments, the system access channel is used to
`transmit differentially encoded access requests including at
`least one state that indicates a request for low rate mode
`and/or burst mode capacity to be scheduled.
`In some embodiments, the wireless terminal further com
`prises: a second transmit chain for generating and transmit
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`ting a burst-mode OFDM transmission transmits occupying
`an assigned space in OFDM frequency-time.
`In some embodiments, the second transmit chain com
`prises a space time encoder adapted to perform space time
`encoding to generate a signal to be transmitted during a plu
`rality of OFDM transmission intervals as said burst-mode
`OFDM transmission.
`In some embodiments, the wireless terminal comprises a
`plurality N of transmit antennas, N>=2, wherein the second
`transmit chain comprises a space time encoder adapted to
`perform space time encoding to generate for each of a plural
`ity of assigned STC Sub-block transmission frequency-time
`locations a respective STC sub-block to be transmitted on
`each transmit antenna.
`In some embodiments, each STC sub-block further com
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`prises pilot symbols.
`In some embodiments, each STC sub-block further com
`prises N pilot symbols on each end of the STC sub-block on
`a respective single OFDM sub-carrier.
`In some embodiments, the wireless terminal further com
`prises a control channel receiver for receiving a downlink
`signalling channel containing instructions for burst mode
`transmission.
`In some embodiments, the instructions comprise a defini
`tion of the assigned STC Sub-block transmission frequency
`time space and a coding/modulation primitive.
`In some embodiments, the instructions further comprise
`rate control commands, the wireless terminal being adapted
`to change the coding/modulation primitive according to the
`rate control commands.
`In some embodiments, the wireless terminal further adapts
`to measure a long term power strength from a serving trans
`mitter and to set a coding/modulation by using multi-level
`progressive coding and modulation feed forward transmis
`Sion.
`In some embodiments, the second transmit chain compris
`ing a hopping pattern generated which defines said assigned
`STC Sub-block transmission frequency-time locations such
`that they hop about in frequency within a subset of the shared
`OFDM band allocated for burst-mode traffic.
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`In some embodiments, the wireless terminal further com
`prises: an access channel transmit chain adapted to generate
`an OFDM access signal occupying a randomly selected slot
`selected from a plurality of slots comprising a frame, each slot
`comprising a predetermined block of OFDM time-frequency.
`In some embodiments, the wireless terminal adapts to
`function in an active and standby state, and further compris
`ing: a control channel receiver for receiving a system access
`channel assignment upon entering the standby State, the sys
`tem access channel assignment being associated with specific
`sub-carriers and OFDM symbols to be used as a system
`access channel; wherein the wireless terminal is further
`adapted to use the system access channel to transmit a pilot
`and system access requests while in the standby State.
`In some embodiments, the wireless terminal adapts to
`function in an active and standby state, and further compris
`ing: a control channel receiver for receiving a system access
`channel assignment upon entering the standby State, the sys
`tem access channel assignment being associated with specific
`sub-carriers and OFDM symbols to be used as a system
`access channel; wherein the wireless terminal is further
`adapted to use the system access channel to transmit a pilot
`and system access requests while in the standby State.
`According to another broad aspect, the invention provides
`a wireless terminal for communicating over a shared OFDM
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`band, the wireless terminal comprising: an access channel
`transmit chain adapted to generate an OFDM access signal
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`occupying a randomly selected slot selected from a plurality
`of slots comprising a frame, each slot comprising a predeter
`mined block of OFDM time-frequency.
`In some embodiments, the wireless terminal further com
`prises: a control channel receiver for receiving an identity of
`a plurality of signature definitions for use in a coverage area;
`wherein the wireless terminal randomly selects one of the
`plurality of signatures and applies the signature in generating
`the access attempt.
`In some embodiments, each slot comprises four OFDM
`symbols, and there are 16 different possible signatures.
`In some embodiments, the wireless terminal further adapts
`to map the signature onto OFDM carriers based on a Peano
`Hilbert plane filling curve.
`In some embodiments, the access channel is overlaid over
`low rate mode OFDM transmissions of other wireless termi
`nals.
`In some embodiments, the wireless terminal adapts to
`function in an active and standby state, and further compris
`ing: a control channel receiver for receiving a system access
`channel assignment upon entering the standby State, the sys
`tem access channel assignment being associated with specific
`sub-carriers and OFDM symbols to be used as a system
`access channel; wherein the wireless terminal is further
`adapted to use the system access channel to transmit a pilot
`and system access requests while in the standby State.
`In some embodiments, the system access channel com
`prises two or more Sub-carriers allocated during certain peri
`odic OFDM symbols.
`In Some embodiments, the system access channel is used to
`transmit differentially encoded access requests including at
`least one state that indicates a request for low rate mode
`and/or burst mode capacity to be scheduled.
`In some embodiments, the wireless terminal further com
`prises: a second transmit chain for generating and transmit
`ting a burst-mode OFDM transmission occupying an
`assigned space in OFDM frequency-time.
`In some embodiments, the second transmit chain com
`prises a space time encoder adapted to perform space time
`encoding to generate a signal to be transmitted during a plu
`rality of OFDM transmission intervals as said burst-mode
`transmission.
`In some embodiments, the wireless terminal comprises a
`plurality N of transmit antennas, N>=2, wherein the second
`transmit chain comprises a space time encoder adapted to
`perform space time encoding to generate for each of a plural
`ity of assigned STC Sub-block transmission frequency-time
`locations a respective STC sub-block to be transmitted on
`each transmit antenna.
`In some embodiments, each STC sub-block further com
`prises pilot sy