(12) United States Patent
`Balachandran et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,975,611 B1
`Dec. 13, 2005
`
`USOO6975611B1
`
`(54)
`
`(75)
`
`(73)
`
`(*)
`
`(21)
`(22)
`
`(60)
`
`(51)
`(52)
`
`(58)
`
`(56)
`
`METHOD AND DEVICE FOR MAC LAYER
`FEEDBACK IN A PACKET
`COMMUNICATION SYSTEM
`
`Inventors: Krishna Balachandran, Morganville,
`NJ (US); Subrahmanyam Dravida,
`Groton, MA (US); Richard P. Ejzak,
`Wheaton, IL (US); Sanjiv Nanda,
`Lunenburg, MA (US); Shiv M. Seth,
`Naperville, IL (US); Stanley Vitebsky,
`Parsippany, NJ (US)
`Assignee: Lucent Technologies Inc., Murray Hill,
`NJ (US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`Appl. No.: 09/517,907
`
`Notice:
`
`Filed:
`
`Mar. 3, 2000
`(Under 37 CFR 1.47)
`Related U.S. Application Data
`Provisional application No. 60/122,616, filed on Mar.
`3, 1999, provisional application No. 60/123,291, filed
`on Mar. 4, 1999.
`Int. Cl................................................ H04B 71212
`U.S. Cl. ...................... 370/337; 370/347; 370/349;
`370/468; 370/522
`Field of Search ................................ 370/498, 329,
`370/442,347,348,328,337, 458, 345,522,
`370/468; 714/746, 748
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`5,910,949 A * 6/1999 Bilstrom et al. ............ 370/337
`
`s
`
`108
`
`MODULATION
`CONTROLLER
`
`MODE
`CONTROLLER
`
`102
`
`-
`
`OO
`
`104
`
`MOBILE
`TRANSCEIVER STATION
`
`10
`MS CHANNEL
`ACCESS
`MANAGER
`
`MS
`SUBCHANNEL
`CONTROLLER
`
`MS
`MAC
`LAYER
`CONTROLLER
`
`114
`
`6,073,016 A * 6/2000 Hulthen et al. .......... 455/435.2
`6,463,073 B1 * 10/2002 Bontu et al. ................ 370/442
`6,577,618 B2 * 6/2003 Diachina et al. ......
`... 370/348
`6,597.680 B1* 7/2003 Lindskog et al. ........... 370/347
`* cited by examiner
`Primary Examiner-Ricky Ngo
`Assistant Examiner-Nittaya Juntima
`
`(57)
`
`ABSTRACT
`
`A method and communication device for media acceSS
`control feedback over a packet channel divided in channel
`time slots is provided. The channel time slots are divided
`into Sub-channel time slots. A packet channel feedback field
`asSociated with each Sub-channel time slot is defined.
`Acknowledgments are indicated using the packet channel
`feedback field. An active mobile identity associated with an
`active mobile Station may be assigned which would then be
`included in the packet channel feedback field. A plurality of
`active mobile identities may be assigned and Some of the
`active mobile identities may be reserved for Special func
`tions. The assigned active mobile identity is used, among
`other things, to identify an active mobile Station to receive
`packet data Signals. The active mobility identity is invali
`dated after one transaction of packet data Signals or invali
`dated after a short number of Such transactions. One or more
`of the assigned active mobile identities may be used to
`indicate a time slot assignment for the active mobile Station.
`A Sub-channel feedback field in the packet channel feedback
`field is used to indicate acknowledgments. A Sub-channel
`assignment field in the packet channel feedback field is used
`to indicate time slot assignments. The Sub-channel assign
`ment field is substantially independent of the sub-channel
`feedback field.
`
`40 Claims, 7 Drawing Sheets
`
`
`
`302
`
`DATA SEGMENT
`
`304
`
`RATE 1A2 NON-SYSTEMATC TAIBITING
`CONVOLUTIONAL ENCODER
`
`300
`
`306
`
`
`
`32
`
`308
`INTERLEAVER AND
`BLOCKER
`
`310
`INTERLEAVER AND
`BLOCKER
`
`320
`
`314
`
`316
`
`'on
`
`DATA BLOCKS
`
`322
`CPCBH PARITYP13-1
`324
`12
`P11-1
`
`PARTY BLOCKS
`
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`

`

`U.S. Patent
`
`Dec. 13, 2005
`
`Sheet 1 of 7
`
`US 6,975,611 B1
`
`
`
`104
`
`MOBILE
`TRANSCEIVER STATION
`110
`MS CHANNEL
`ACCESS
`MANAGER
`
`MODULATION
`CONTROLLER
`
`MS
`SUBCHANNEL
`CONTROLLER
`
`MS
`MAC
`LAYER
`CONTROLLER
`
`114
`
`s
`108
`
`102
`
`MODE
`CONTROLLER
`
`10-1
`
`
`
`952
`
`708
`
`956 958 960
`
`FIG 11
`
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`

`

`U.S. Patent
`
`Dec. 13, 2005
`
`Sheet 2 of 7
`
`US 6,975,611 B1
`
`200 N.
`
`2O2
`
`MLC
`OPEN. REQ()-204 206
`SCC: READY
`
`FIG. 2A-1
`
`208
`
`L1
`PHYDATA.IND
`(L1 SDU, PCF, DFTISFP)
`
`TSLBNDRY |
`
`Start TSLBNDRY
`
`210
`
`CAM
`Data, req
`(Coded MAC PDU, DFT)
`Ll
`
`238
`
`EXTRACT CODED
`
`CASE=1.
`-
`
`START
`T SLBNDRY
`
`216
`
`Coded MAC PDU
`
`236
`
`214
`
`CAM
`PHYDATAREQ 236
`Pef, ind (Status)
`(Ll SDU, DFT
`N-238
`SCC2: BURST TRANSMITTED
`
`240
`
`PHY DATA.IND
`(L1 SDU, PCF, DFTISP)
`
`L1
`
`244
`
`EXTRACT CODED
`
`248
`EXTRACT R /N,
`DLE <GS> RSVD C/S AND COF
`SUBFIELDS OF SLF
`258
`
`N
`
`250
`AMCurrent
`254
`R
`CAM
`Data.COn
`Data.COn
`Data.COn
`(null, idle, null,
`(error, RSVd, CQF,(null, RSVd, CQF,
`SFP)
`SFP)
`SFP)
`
`260
`
`CASE= 4
`
`
`
`CAM
`Data.COn
`(error, idle, null,
`SFP)
`
`
`
`CASE=1.
`
`SCC3: WAIT FOR SLOT BOUNDARY
`
`218
`
`FROM FIG. 2A-2
`
`TO FIG. 2A-2
`
`FROM FIG. 2A-2
`
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`

`

`U.S. Patent
`
`Dec. 13, 2005
`
`Sheet 3 of 7
`
`US 6,975,611 B1
`
`TO FIG, 2A-l
`
`
`
`TO FIG. 2A-l
`
`FROM FIG. 2A-1
`
`Current
`
`Current
`
`Status=idle Status=RSVd Status=RSVd Status=RSVCStatus=RSVd
`Status=idle
`234
`264
`268
`
`FIG. 2A-2
`
`IPR2018-1556
`HTC EX1015, Page 4
`
`

`

`U.S. Patent
`
`975,611 B1
`
`
`
`
`
`ndd OWW QEQ00 10WHIXE
`
`
`
`
`
`
`
`
`
`902
`
`Cd
`CN
`
`IPR2018-1556
`HTC EX1015, Page 5
`
`

`

`U.S. Patent
`
`Dec. 13, 2005
`
`Sheet 5 of 7
`
`US 6,975,611 B1
`
`302
`
`DATA SEGMENT
`
`304
`
`RATE 1/2 NON-SYSTEMATIC TALBITING
`CONVOLUTIONAL ENCODER
`
`306
`
`300
`/
`
`
`
`320
`
`D12
`
`324
`
`CPCBHPARITYP12 326
`P11-1
`
`DATA BLOCKS
`
`PARTY BLOCKS
`
`402
`
`400
`
`PCBP=00 CDSH
`FIG. 4 g PCBP-01
`402
`PCBP=10
`
`PCBP=00
`402
`PCBP= 01
`
`PCBP=10
`402
`PCBP=11
`
`
`
`402
`
`FIG. 5
`
`FIG. 6
`
`l
`
`2
`
`10
`
`602
`
`604
`
`606
`
`
`
`
`
`
`
`
`
`IPR2018-1556
`HTC EX1015, Page 6
`
`

`

`U.S. Patent
`
`Dec. 13, 2005
`
`Sheet 6 of 7
`
`US 6,975,611 B1
`
`700
`
`14
`SYNC
`
`6
`CFSP/CDFT
`
`708
`12
`
`128
`DATA
`
`78
`
`2
`PRAMP
`
`T/4-DQPSK
`
`704
`
`706
`
`DATAPDATA PDATAPIDATAP 8-PSK
`720 710 722 712 724 714. 726 716
`
`16
`
`FIG 7
`
`
`
`s
`
`810
`
`806
`3 3
`8
`14
`GR PRAMP SYNC
`
`812 3
`CDF
`
`
`
`
`
`
`
`131
`DATA
`
`T/4-DQPSK
`
`804.
`
`808
`
`
`
`
`
`824
`
`826
`
`828
`
`- DATAPIDATAPIDATAPIDATAP 8-PSK
`
`802
`
`822
`
`26 / 3
`814
`
`31
`
`3
`816
`
`31
`
`3
`818
`
`31
`
`3
`820
`
`FIG. 8
`
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`HTC EX1015, Page 7
`
`

`

`US. Patent
`
`Dec. 13, 2005
`
`Sheet 7 0f 7
`
`US 6,975,611 B1
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`HTC EX1015, Page 8
`
`IPR2018-1556
`HTC EX1015, Page 8
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`
`
`
`
`

`

`US 6,975,611 B1
`
`1
`METHOD AND DEVICE FOR MAC LAYER
`FEEDBACK IN A PACKET
`COMMUNICATION SYSTEM
`
`RELATED APPLICATIONS
`
`The benefit of the filing date of U.S. provisional applica
`tion Ser. No. 60/122,616, filed on Mar. 3, 1999, and U.S.
`provisional application Ser. No. 60/123,291, filed on Mar. 4,
`1999, is hereby claimed for this application under 35 U.S.C.
`S 119(e).
`BACKGROUND OF THE INVENTION
`
`2
`allocated to a digital control channel (DCCH) and/or digital
`traffic channel (DTC). APDCH may be full rate, double rate
`or triple rate depending on whether 1, 2 or 3 time slot pairs
`are allocated to the channel within each 40 ms frame.
`A multi-rate PDCH operates on a single channel fre
`quency and consists of primary and Secondary phases. In this
`context, a phase corresponds to a full rate portion of a
`multi-rate PDCH. The primary phase always corresponds to
`a full rate channel and is the only full rate channel that
`contains logical paging and broadcast channels on the down
`link. Nominal paging time slots are determined using a
`Standard hashing algorithm that relies on mobile Station
`(subscriber) identity. Sleep mode similar to the IS-136
`DCCH is defined for mobile stations in order to improve
`Standby time.
`In addition, the shared channel feedback (SCF) proce
`dures and fields as specified in IS-136 DCCH are not
`well-Suited for long packet data transactions and do not
`facilitate flexible sharing of resources among users.
`Accordingly, there is a need in the art for a method and
`device for handling contention in a better and more flexible
`manner and for assigning time slots in a more flexible
`C.
`
`SUMMARY OF THE INVENTION
`
`This need is met by a method and device in accordance
`with the present invention which employs an active mobile
`identity for acknowlegements and time slot assignments in
`a flexible, efficient manner.
`In accordance with one aspect of the present invention, a
`method for media access control feedback over a packet
`channel divided in channel time slots is provided in a
`communication System. The method is comprise of the Steps
`of dividing the channel time slots into Sub-channel time
`Slots. A packet channel feedback field associated with each
`Sub-channel time slot is then defined. Acknowledgments are
`indicated using the packet channel feedback field.
`The method may comprise assigning an active mobile
`identity associated with an active mobile Station which is
`then included in the packet channel feedback field. ASSign
`ment of the active mobile identity may be during a trans
`action initiation procedure in the System. A plurality of
`active mobile identities may be assigned and Some of the
`active mobile identities may be reserved for Special func
`tions.
`The assigned active mobile identity may be used to
`identify an active mobile Station to receive packet data
`Signals. In a preferred embodiment of the present invention,
`the active mobility identity is invalidated after one transac
`tion of packet data Signals. The active mobile identity may
`alternatively be invalidated after a short number of Such
`transactions.
`One or more of the assigned active mobile identities may
`be used to indicate a time slot assignment for the active
`mobile Station. The Step of transmitting may comprise the
`Steps of: forming a Sub-channel feedback field in the packet
`channel feedback field to indicate acknowledgments, and
`forming a Sub-channel assignment field in the packet chan
`nel feedback field to indicate time slot assignments, the
`Sub-channel assignment field being Substantially indepen
`dent of the Sub-channel feedback field.
`A format of the sub-channel feedback field may depend
`on whether it is in response to a contention acceSS or a
`reserved access. The Sub-channel feedback field may com
`prise an active mobile identity that indicates acknowledg
`ment in response to a contention access.
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`The present invention relates generally to a method and
`device for media access layer feedback in a packet data
`communication System and, more particularly, to a method
`and device for providing acknowledgments and time slot
`assignments using a new packet channel feedback field.
`Current North American Time Division Multiple Access
`(TDMA) systems Support voice Services and circuit data
`Services at a rate limited to 9.6 kb/s. High rate packet data
`Services are desirable for short bursty transactions and other
`applications, Such as world wide web/internet access, elec
`tronic mail and file transfer. Accordingly, the Telecommu
`nications Industry ASSociation (TIA) has adopted flexible,
`high performance Medium Access Control (MAC) and
`Radio Resource Management procedures for high rate
`packet data services over IS-136 TDMA channels. The
`characteristics of these procedures, Such as a 30 kHZ channel
`bandwidth, symbol rate and TDMA format (6 time slots
`every 40 ms), are in compliance with the IS-136 standard to
`provide compatibility with existing mobile units and in order
`to minimize impact on existing infrastructure.
`The standards for the packet data MAC and physical layer
`have been designed to Support higher data rates through the
`use of higher modulation Schemes. The Standard is designed
`to permit dynamic adaptation of the modulation Scheme
`based on measured carrier to interference ratios (C/Is).
`Supported modulation Schemes include coherent 8 phase
`shift keying (PSK) and JL/4 Differential Quadrature Phase
`Shift Keying (DQPSK).
`AS Set forth in the Standards, a packet data channel
`(PDCH) is provided consisting of six logical channels. In
`particular, the PDCH consists of a packet broadcast channel
`for indicating generic System configuration related informa
`tion, a packet paging channel dedicated to delivering pages,
`a downlink packet payload channel for delivering data
`generated by Logical Link Control (LLC) and General
`Packet Radio Services (GPRS) Mobility Management,
`Packet Channel Feedback (PCF) for support of random
`access and reserved acceSS on the uplink, uplink packet
`random acceSS channel used by mobile Stations to request
`packet data access to the System and reverse packet payload
`channel for delivering data generated by the LLC and GPRS
`55
`Mobility Management.
`Unfortunately, the PDCH has a limited 30 kHz channel
`bandwidth which thus necessarily restricts the data rates that
`can be Supported. Accordingly, there is a need in the art for
`methods and Systems which increase the data rates possible
`over the PDCH and are in compliance with the standards for
`IS-136 time division multiple access systems.
`The PDCH uses 30 kHz radio frequency channels and the
`time slotted structure specified in IS-136. Each 40 ms frame
`on a 30 kHz. RF channel consists of 6 time slots (3 time slot
`pairs), numbered 1 to 6. One or more time slot pairs may be
`allocated to a PDCH. The remaining time slot pairs may be
`
`60
`
`65
`
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`

`US 6,975,611 B1
`
`3
`In accordance with another aspect of the present inven
`tion, a method for transmitting packet data Signals in a time
`Slotted packet channel is provided. The method comprises
`the Steps of: creating Sub-channel time slots associated with
`the time slotted packet channel; defining an active mobile
`identity associated with an active mobile Station; and iden
`tifying acknowledgments using the active mobile identity.
`In accordance with yet another aspect of the present
`invention, a communication device, Such as a mobile Station,
`for communicating via packet data Signals over a packet
`channel is provided. A Sub-channel controller identifies
`acknowledgments and assignments of time slots on the
`packet channel based on a packet channel feedback field. A
`channel access manager controls access to the packet chan
`nel based on the acknowledgments and assignments. The
`Sub-channel controller may identify acknowledgments
`based on the packet channel feedback field and a active
`mobile identity associated with the communication device.
`These and other features and advantages of the present
`invention will become apparent from the following detailed
`description, the accompanying drawings and the appended
`claims.
`
`15
`
`4
`(MS) 104. Although only one base station and mobile station
`are shown in FIG. 1, those skilled in the art will readily
`comprehend that there are typically multiple base Stations
`and mobile Stations in a wireleSS communications System.
`The BS 102 transmits and receives Signals, Such as packet
`data units (PDUs), to and from the MS 104 over a commu
`nication channel, shown generally at reference numeral 108.
`AMS channel access manager (CAM) 110 controls access
`of the MS 104 to the communication channel 108. AS
`described more fully below, a MS Subchannel Controller
`112 processes PDUs for transmission over the channel 108
`and recovers PDUs from the physical layer of received
`signals and sends them to the CAM 110. A Media Access
`Control Layer Controller (MLC) 114 controls communica
`tions on the media acceSS control layer. A transceiver 116
`transmits PDUs to and receives PDUs from the base station
`102.
`A modulation controller 118 selects a modulation format
`in which the packet data Signals will be formatted. A mode
`controller 120 selects either an incremental redundancy
`mode or a fixed coding mode for transmission. Advanta
`geously as set forth more fully below, the system 100 may
`Select modulation formats and modes for each time slot of
`the packet data Signals. It should be understood that although
`the various controllers are shown located in the mobile
`station 104, the base station 102 has similar controllers.
`However, the base station controller would need additional,
`or slightly different, functions than the mobile Station con
`trollers. For example, the base station 102 must multiplex
`multiple mobile Stations.
`The present invention is generally directed to improved
`media access control (MAC) and Radio Resource Manage
`ment (RRM) in cellular packet communications. Although
`the present invention will be described primarily with ref
`erence to packet communications over IS-136 channels,
`principles in accordance with the present invention may be
`implemented in any number of packet communication Sys
`temS.
`In accordance with the present invention, a MAC function
`comprises various procedures, Such as packet data channel
`(PDCH) selection, reassignment and reselection. During
`these processes, mobile stations are directed to a PDCH
`through IS-136 digital control channel (DCCH) broadcast
`information. If there are multiple PDCHs per sector, mobile
`stations are directed to a Beacon PDCH. Broadcast infor
`mation on the Beacon PDCH indicates the number of
`PDCHs, as well as the bandwidth (full-rate, double-rate or
`triple-rate) of each support PDCH. Mobile stations then hash
`on to a particular PDCH depending on their identity and the
`number of PDCHs.
`Load balancing may be carried out by reassigning mobile
`Stations acroSS radio resources and performance may be
`further improved by maintaining MAC/Radio Link Protocol
`(RLC) state across reassignments. Cell reselection proce
`dures ensure continuity of Service acroSS cell boundaries
`since mobile stations autonomously perform PDCH reselec
`tion when they detect a stronger Signal from a neighbor cell.
`In accordance with the present invention, Active Mobile
`Identity Management (AMIM) is implemented. In AMIM,
`each mobile Station is assigned a temporary local identifier,
`preferably consisting of Seven (7) bits, designated as an
`active mobile identity (AMI) field which remains valid for
`one or Several closely spaced transactions. The AMI is used
`to identify uplink time slot assignments and to identify a
`recipient of data on the downlink. Of the 128 possible AMI
`field values, preferably only 89 values are permitted for
`mobile Stations engaged in point to point transactions. By
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`25
`
`35
`
`The foregoing and other advantages of the invention will
`become apparent upon reading the following detailed
`description and upon reference to the drawings in which:
`FIG. 1 is block diagram of a communications System in
`accordance with the present invention in which the method
`of the present invention may be advantageously imple
`mented;
`FIGS. 2A and 2B are a flowchart of a process performed
`by a mobile station Subchannel Controller (SCC) in accor
`dance with the present invention relating to contention
`acceSS,
`FIG. 3 illustrates a method for incremental redundancy
`Segment encoding for transmitting data in the communica
`tion System of the present invention;
`FIG. 4 shows a composition of an incremental redun
`40
`dancy CONTINUE packet data unit for L/4-DQPSK modu
`lation;
`FIG. 5 illustrates a composition of an incremental redun
`dancy CONTINUE packet data unit for 8-PSK modulation;
`FIG. 6 shows a structure of a data Segment header
`showing a number of bits required for each of the fields in
`the header;
`FIG. 7 shows a downlink time slot format;
`FIG. 8 shows an uplink time slot format;
`FIG. 9 is a table setting forth FC mode CONTINUE PDU
`50
`format sizes and corresponding peak triple rate PDCH
`throughput in kb/s,
`FIG. 10 is a table setting forth IR mode CONTINUE PDU
`format sizes and corresponding peak triple rate PDCH
`throughput in kb/s, and
`55
`FIG. 11 shows a logical format of a packet channel
`feedback in accordance with one aspect of the present
`invention.
`
`45
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`In accordance with the present invention, a wireleSS
`communications system 100 is shown in FIG. 1 in which the
`method of the present invention may be advantageously
`implemented. The system 100 comprises communication
`devices, such as a base station (BS) 102 and a mobile station
`
`60
`
`65
`
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`

`S
`restricting the allowed values of the AMI, the reliability of
`the transmitted coded version of the field is improved. One
`or more, or a Subset, of the active mobile identities may
`therefore be used for special functions and not for mobile
`Station identification.
`AMI assignment procedures are preferably executed for
`both uplink and downlink transactions Spanning more than
`one time slot. If a valid AMI has not already been assigned,
`the AMI assignment is carried out as a part of a transaction
`initiation procedure. Once an AMI has been assigned to a
`mobile Station, it is used for transactions in both uplink and
`downlink directions.
`The present invention provides a procedure for transac
`tion initiation. A new transaction is initiated by a transmit
`controller when a transmission opportunity is identified and
`if a transmit buffer contains new data. Downlink transactions
`may be acknowledged or unacknowledged but uplink trans
`actions are always acknowledged. The initiation of a new
`transaction is carried out through the transmission of a
`BEGIN Protocol Data Unit (PDU). The acknowledged
`transfer of the BEGIN PDU is used to initialize the AMI and
`a RLP protocol in either Incremental Redundancy (IR) Mode
`or Fixed Coding (FC) Mode for the transaction.
`In accordance with the present invention, the RLP oper
`ates in two modes: incremental redundancy (IR) and fixed
`coding (FC) modes. For both modes, the retransmission
`Scheme is based on a TDMA circuit data RLP as set forth in
`IS-136. Under IS-136, retransmissions are given priority
`over new data and retransmissions are determined by the
`transmitter based on receiver-state feedback (bitmap feed
`back). Retransmissions are not based on timers or an accu
`rate knowledge of the round-trip delay. Extensions to the
`RLP as set forth in IS-136 have been defined for operation
`at the MAC layer for packet data transactions, with modu
`lation adaptation, and using the incremental redundancy
`35
`mode.
`Seamless operation acroSS adaptive modulation is
`achieved through the use of fixed size data and parity blockS
`in the IR mode and fixed size coded data segments in the FC
`mode. Different integer number of these fixed size blocks or
`segments can be accommodated in the MAC PDU for
`different modulations.
`An uplink MAC procedure using a generic packet channel
`feedback (PCF) field is provided in the present invention.
`The PCF uses a minimal set of flags which are defined to
`provide acknowledgments and assignments on Sub-channels
`(time slots) associated with the PDCH. The PCF allows the
`efficient management of contention access and reserved
`access on the same channel. The flags are coded according
`to the reliability needed for the functions being carried out.
`A more detailed discussion of the PCF in accordance with
`the present invention is provided below.
`MAC PDUs transmitted on the uplink are acknowledged
`via the PCF mechanism. Optionally, full or partial bitmap
`feedback may be provided by the base station via ARQ
`55
`Status PDUs. The transmitter may poll the receiver for
`bitmap feedback at any time. For downlink data transfer, the
`base Station may provide the mobile Station with reservation
`opportunities to obtain bitmap feedback. Local variables and
`tables maintained at the transmitter and receiver contain the
`update procedures and a detailed description of the protocol
`using the Specification and Description Language (SDL)
`and are part of the MAC layer Specification.
`In accordance with the present invention, a procedure for
`contention access is provided. Contention slots are provided
`on the PDCH in order to allow mobile stations to initiate
`packet data transactions. A mobile Station identifies a con
`
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`US 6,975,611 B1
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`tention opportunity by reading the PCF field. If the mobile
`Station attempts transmission in a contention slot and is
`negatively acknowledged by the base Station, it starts a timer
`and waits for an AMI and/or mode assignment from the base
`Station. AMI assignment may be provided by the base Station
`102 through a downlink ARQ Status PDU. If no AMI or
`mode assignment is received and the timer expires, the
`mobile station must wait for T Retry idle (contention) slots
`before making another acceSS attempt.
`The parameters used by Such a random acceSS procedure
`in accordance with the present invention are Set forth in
`Table 1.
`
`Parameter
`
`Access Count Max
`
`Access Count
`
`T Retry
`
`T Retry Init
`C.
`
`TABLE 1.
`
`Description
`
`Maximum number of access attempts
`before declaring failure.
`Counter for number of contention access
`attempts.
`Number of contention slots that the mobile
`station must wait before another
`transmission attempt.
`Initial value of T Retry Max.
`Configurable parameter.
`
`T Retry is a uniformly distributed integer in the closed
`interval O, T Retry Max where T Retry Max is deter
`mined as a function of AcceSS Count, T Retry Init and C.
`The parameter T Retry MaX may be computed using the
`expressions in Table 2.
`
`TABLE 2
`
`Access Count
`
`T Retry Max
`
`O
`1,2,... Access Count Max
`
`O
`T Retry Init (2)^
`A = (Access Count - 1)/C.
`
`The access parameters, the AcceSS Count Max,
`T Retry Init and the C. are optionally transmitted over a
`fast packet broadcast control channel (F-PBCCH). If these
`values are not indicated, the default values in Table 3 below
`may be assumed.
`
`TABLE 3
`
`Parameter
`
`Default Value
`
`Access Count Max
`T Retry Init
`C.
`
`5
`6
`1.5
`
`If the mobile station 104 is unsuccessful after
`(Access Count Max+1) access attempts, the CAM 110
`provides an access failure indication to the MLC 114. In the
`transmit direction, the Subchannel Controller 112 processes
`Coded MAC PDUs for transmission over the radio inter
`face. In the receive direction, the Subchannel Controller 112
`recovers the Coded MAC PDUs from the physical layer
`and sends them to the CAM 110.
`The mobile station Subchannel Controller (SCC) 112 may
`perform a process 200 shown in FIGS. 2A and 2B. A base
`Station Subchannel Controller performs a similar process.
`The following variables and timers set forth in Table 4 are
`used in FIGS 2A and 2B:
`
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`US 6,975,611 B1
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`Variable
`
`Values
`
`Description
`
`TABLE 4
`
`AMI current (Global)
`AMI idle
`
`AMI idle, AMI values
`O
`
`AMI set flag (Global)
`
`True, False
`
`Continue, Stop
`
`Case
`
`1,2,3,4
`
`Coded MAC PDU
`
`Data
`
`DFT
`
`Error
`L1 SDU
`
`MAC PDU
`PCF
`
`Quality RX
`R/N
`
`SFP
`
`SLA
`
`SLF
`Status
`
`0,1, . . . .4
`
`Error, Null
`Data
`
`Data
`(SLA (AMI or R/N, CIS,
`CQFI), SLF)
`CQF, Null
`Received, Not Received
`
`0,1,2,. . . .31
`
`AMI idle or AMI value
`
`AMI or R/N, CIS, COF
`Idle, RSvd
`
`T SLBNDRY
`
`timer
`
`Mobile station's AMI value.
`Default AMI value
`corresponding to contention
`slot assignment or point to
`multipoint slot assignment.
`Indicates whether a valid
`AMI has been assigned to
`the mobile station.
`Indicator of whether this
`mobile station continues to
`have next time slot reserved
`for it.
`Variable to provide
`temporary decision switch.
`Encoded data for
`transmission.
`Data Frame Type. Indicates
`mode, modulation and AMI
`type.
`Error identifier.
`Data from PDU from L1
`Interface.
`PDU Data.
`Packet channel feedback
`data.
`Quality factor received.
`Status of reception success
`for preceeding timeslot.
`Super Frame Phase
`indicator.
`Slot Assignment indicator.
`Identifies AMI assigned for
`next slot.
`Slot Feedback flag.
`Status of next slot.
`Idle: next slot available for
`contention access.
`Rsvd: next slot reserved for
`current mobile station.
`Timer which expires on
`time slot boundary when
`transmission must start for
`the corresponding SCC.
`
`The MAC Layer has 9 Sub-channel Controllers for a
`triple rate channel, 6 for a double rate channel and 3 for a full
`rate channel. Each SCC handles PCF operation for the
`sub-channel and passes coded MAC PDUs between the
`CAM and the Physical Layer.
`
`The mobile station SCC may be in one of three states:
`SCC0 (Idle), SCC1 (Ready) and SCC2 (Burst Transmitted). So
`The primitives exchanged by SCC for each SCC state are set
`forth in Table 5.
`
`Referring now to FIGS. 2A and 2B, from idle state SSCO
`at step 202, the SCC transitions to state SCC1 on receiving
`an Open.req primitive from the MLC at step 204. While in
`45 the SCC1, or Ready, state at step 206, the SCC may receive
`one of the following primitives:
`At step 208, a PHY DATA.IND primitive from the
`Physical Layer (Layer 1) which includes a Layer 1
`SDU, PCF, DFT and AMI.
`At step 210, a Data.Req primitive from the CAM which
`includes a Coded MAC PDU and the DFT.
`At step 212, Close. Req primitive from the MLC.
`
`SCC State
`
`SCCO (Idle)
`SCC1 (Ready)
`
`SCC2 (Burst Transmitted)
`
`TABLE 5
`
`Input Signals
`Open. Req from MLC
`Close. Req from MLC
`PHY DATA.IND from Layer 1
`Data. Req from CAM
`Close. Req from MLC
`PHY DATA.IND from
`Layer 1
`Close. Req from MLC
`
`Output Signals
`
`pcfind(Status) to CAM
`data.ind to CAM
`PHY DATA.REQ to Layer 1
`pcfind(Status) to CAM
`data.ind to CAM
`Data.com to TC
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`On receiving a PHY DATA.IND primitive, the SCC does
`the following (in order):
`It executes the procedure titled “Check Destination and
`Extract Coded MAC PDU” at step 214 and also shown
`in FIG.2B. As part of this procedure, the PCF, DFT and
`AMI fields are decoded, and the coded MAC PDU is
`extracted from the Layer 1 SDU (L1 SDU) at steps
`215 and 217. At step 216, if the assigned AMI
`(AMI current) matches the recipient AMI or if the
`recipient AMI is point to multi-point (AMI idle), the
`SCC uses a data.ind primitive to pass the Coded MAC
`PDU and DFT to the CAM at step 218.
`The SCC then checks the SA field for a transmission
`opportunity at StepS 220 and 222. At Step 224, on
`obtaining
`reserved
`CCCSS
`opportunity
`(AMI set flag=True and SA=AMI current at steps
`226 and 228) or a contention opportunity (SA=
`AMI Idle) at step 230, the SCC sets Status=Rsvd at
`step 232 or Status=Idle at step 234 respectively, and
`indicates the transmission opportunity to the CAM
`using a pcfind(Status) primitive at steps 236 and 238.
`On receiving a Data.req primitive at step 210 from the
`CAM, the SCC executes a procedure which constructs the
`L1 SDU at step 236, encodes the AMI and DFT at step 238.
`The SCC then provides the L1 SDU, AMI and DFT to the
`Physical Layer through a PHY DATA.REQ primitive and
`enters the SCC2 state at step 240. On receiving a Close. Req
`primitive, the SCC transitions to the SCC0 state at step 242.
`While in the SCC2 state, the SCC may obtain a
`PHY DATA.IND primitive from the physical layer at step
`244 or a Close. Req primitive from the MLC. On receiving
`the PHY DATA.IND primitive, the SCC does the following
`(in order):
`At step 246, it executes the procedure titled “Check
`Destination and Extract Coded MAC PDU.” As part of
`this procedure, the PCF, DFT and AMI fields are
`decoded, and the coded MAC PDU is extracted from
`the Layer 1 SDU (L1 SDU). If the assigned AMI
`(AMI current) matches the recipient AMI or if the
`recipient AMI is point to multi-point (AMI idle), the
`40
`SCC uses a data.ind primitive to pass the Coded MAC
`PDU and DFT to the CAM.
`At step 248, the SCC assumes a different structure for SF
`depending on whether the previous burst was transmit
`ted in a contention slot (SF=Idle) or a reserved slot
`(Status=RSVd).
`If Status=Idle, the SCC goes to step 250 and does the
`following:
`On receiving an ACK (i.e., SF=AMI current), at
`step 254, it provides a Datacon primitive to the
`50
`TC in order to validate the AMI. It then checks SA
`to determine if it has been granted a reservation
`opportunity. The SCC sets Status=Idle or
`Status=RSVd
`depending
`O
`whether
`SA=AMI idle or SA= AMI current (if the AMI
`55
`is valid).
`On declaring a NAK (i.e., SF not equal to
`AMI current), the SCC provides a Data.con error
`indication at step 256 to the TC. The SCC sets
`Status=Idle or Status=RSVd depending on whether
`60
`SA=AMI Idle or SA=AMI current (if the AMI
`is valid).
`If Status=Rsvd at step 248, the S