a2) United States Patent
`US 8,699,587 B2
`(0) Patent No.:
`Apr.15, 2014
`(45) Date of Patent:
`Blanzetal.
`
`US008699587B2
`
`(54)
`
`FEEDBACK OF PRECODING CONTROL
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`INDICATION (PCD AND CHANNEL QUALITY
`INDICATION (CQDIN A WIRELESS
`COMMUNICATION SYSTEM
`
`(75)
`
`Inventors: Josef J. Blanz, Wachenheim (DE); Ivan
`Jesus Fernandez-Corbaton, Nuremberg
`(DE)
`
`(73)
`
`Assignee: QUALCOMMIncorporated, San
`Diego, CA (US)
`
`Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`USS.C. 154(b) by 1115 days.
`
`(21)
`
`Appl. No.: 11/841,549
`
`(22)
`
`Filed:
`
`Aug. 20, 2007
`
`(65)
`
`(60)
`
`(51)
`
`(52)
`
`(58)
`
`Prior Publication Data
`
`US 2008/0043867 Al
`
`Feb. 21, 2008
`
`Related U.S. Application Data
`
`Provisional application No. 60/838,677, filed on Aug.
`18, 2006.
`
`Int. Cl.
`
`(2006.01)
`
`HO4L 27/28
`US. Cl.
`USPC oo. 375/260; 375/219; 375/267, 375/295;
`375/316; 375/347; 455/69
`Field of Classification Search
`CPC .. H04B 7/0632; H04B 7/0626; H04B 7/0634;
`H04B 7/0639; H04B 7/0645
`USPC Loe 375/219, 260, 267, 295, 316, 347;
`455/69, 455
`See application file for complete search history.
`
`5/2006 Waltonet al.
`7,047,016 B2
`7,466,666 B2* 12/2008 Yoonetal. wo. 370/278
`7,688,899 B2
`3/2010 Ketchum etal.
`2006/0007889 AL*
`1/2006 Khan wee 370/331
`
`(Continued)
`
`FOREIGN PATENT DOCUMENTS
`
`CN
`CN
`
`1395375 A
`1773885 A
`
`2/2003
`5/2006
`
`(Continued)
`OTHER PUBLICATIONS
`
`UMTSPhysical layer procedures 3GPP TS 25.214 document (Dec.
`2003).*
`
`(Continued)
`
`Primary Examiner — Sophia Vlahos
`(74) Attorney, Agent, or Firm — Dalei Dong
`
`ABSTRACT
`(57)
`Techniques for sending feedback information in a wireless
`communication system are described. In one design, precod-
`ing control indication (PCI), rank, and channel quality indi-
`cation (CQI) for data transmission from a transmitter to a
`receiver may be determined by evaluating different hypoth-
`eses. A report may be formedbased on the PCI, rank and CQI.
`The PCI mayinclude a precoding matrix or vector to use for
`the data transmission. The CQI mayincludeat least one CQI
`value for at least one transport block to send for the data
`transmission. The rank and CQ] may be combined based on a
`mapping. For example, the CQ] may include one CQIvalue
`and fall within a first range of valuesif one transport block is
`preferred by the receiver. The CQ] may include two CQI
`values and fall within a second range ofvalues iftwo transport
`blocksare preferred.
`
`55 Claims, 6 Drawing Sheets
`
`700
`
`Determine PCI for data
`transmission from a transmitter (e.g.,
`a NodeB)to a receiver(e.g., a UE)
`714
`
`Determine CQI for
`the data transmission
`
`Send the report to the transmitter
`
`Determinea rankindicative of
`the numberof transport blocks
`to send for the data transmission
`
`Form a report based on
`the PCI, rank and CQI
`
`167
`
`718
`
`720
`
`APPLE 1011
`
`1
`
`APPLE 1011
`
`

`

`US 8,699,587 B2
`Page 2
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`Written=Opinion—PCT/US07/076076—International Search
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`5/2006 Oh et al.
`2006/0098568 Al
`5/2006 Caietal. wo. 375/260
`2006/0109923 Al*
`6/2006 Sampath etal.
`2006/0133521 Al
`2006/0223449 Al* 10/2006 Sampath etal. 0.0... 455/69
`
`2007/0183380 Al*
`. 370/338
`8/2007 Rensburg etal. .....
`2007/0191066 Al*
`ws 455/562.1
`8/2007 Khojastepour etal.
`2007/0223423 Al
`9/2007 Kim etal.
`2008/0013610 Al*
`. 375/221
`.
`1/2008 Varadarajan et al.
`2008/0069031 Al*
`3/2008 Zhang etal. we. 370/328
`
`
`(56)
`References Cited
`Authority—European Patent Office, Munich—Feb.7, 2008.
`U.S. PATENT DOCUMENTS
`“Physical Channels and Mapping of Transport Channels onto Physi-
`cal Channels (FDD),” 3GPP, TS 25.211 V7.0.0, Mar. 2006.
`“Physical Layer Procedures (FDD),” 3GPP, TS 25.214 V7.1.0, Jun.
`2006.
`Cingular Wireless, Orange, 3, Telecom Italia, T-MObile, Vodafone
`Group, “Reference scenario for the evolution of the UTRA MIMO
`Scheme,” 3GPP, TS RANI, Tdoc R1-051626, Dec. 2005.
`ETSI MCC,“Draft Report of the 32nd 3GPP TSG RAN meeting,”
`(Warsaw, Poland May 31-Jun. 2, 2006), 3GPP TSG RAN email
`reflector, Jun. 2006.
`Nokia, “MIMO schemefor consideration in UTRA MIMOevalua-
`tions,” 3GPP TSG-RAN1, Tdoc R1-060281, Feb. 2006.
`3GPP TSG RAN1, “LS on Rel-7 MIMOConclusions,” 3GPP TSG
`RANI Tdoc RP-060343, May 2006.
`Motorola, “MIMO Evaluation Proposal,” 3GPP, TSG RANI, Tdoc
`R1-060615, Feb. 2006.
`Nokia. “D-TxAA, PARC, and Single Antenna Systems in Urban
`Microcells.” 3GPP, TSG Rant. Tdoc. R1-061119. May 2006.
`Motorola, “D-TxAA, PARC,and Single Antenna Systems in Urban
`Microcells,’” 3GPP, TSG RANI, Tdoc, R1-061206, May 2006.
`Qualcomm Europe, “Cell and User Throughput Comparison for 2x2
`MIMO: D-TxAA and PARC,” 3GPP, TSG RANI, Tdoc R1-061491,
`May 2006.
`
`
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`EP
`EP
`JP
`JP
`JP
`KR
`
`1/2003
`1274178
`5/2006
`1655871
`5/2006
`1655874
`6/2006
`2006141013 A
`3/2007
`2007505589 A
`1/2010
`2010502114
`5/2006
`1020060042523
`OTHER PUBLICATIONS
`
`LG Electronics “MIMO-OFDM Technology for Networking Engi-
`neers”, Jun. 2006, pp. 1-32.*
`International Search Report—PCT/US07/076076—International
`Search Authority, European Patent Office, Feb. 7, 2008.
`
`* cited by examiner
`
`2
`
`

`

`U.S. Patent
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`Apr. 15, 2014
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`U.S. Patent
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`Apr. 15, 2014
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`Sheet 4 of 6
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`US8,699,587 B2
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`
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`FIG. 4
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`6
`
`

`

`U.S. Patent
`
`Apr. 15, 2014
`
`Sheet 5 of 6
`
`US8,699,587 B2
`
`H-ARQ ACK/NAK
`1 Bit / 2 Bits
`
`PCI & CQI
`10 Bits
`
`ACK/NAK
`Channel Coding
`
`Channel Coding,
`e.g., (20, 10)
`
`10
`CodeBits
`
`20
`Code Bits
`
`Physical
`Channel
`Mapping
`
`Physical
`Channel
`Mapping
`
`Modified RM Code
`
`
`HS-DPCCH
`
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`Time
`
`FIG. 5
`
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`
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`
`7
`
`

`

`U.S. Patent
`
`Apr. 15, 2014
`
`Sheet6 of 6
`
`US 8,699,587 B2
`
`700
`
`Determine PCI for data
`transmission from a transmitter (e.g.,
`a Node B)to a receiver(¢.g., a UE)
`
`Receive a report comprising
`PCI, rank and CQI
`
`Determine the rank or number
`of transport blocks to send for
`the data transmission based on
`one of multiple ranges of values
`within which the CQI falls
`
`matrix or vector from the PCI
`
`Process (e.g., encode and modulate)
`at least one transport block based on
`at least one CQI value from the CQI
`
`Precode the at least one
`transport block based on a precoding
`
`
`
`Determine CQI for
`the data transmission
`
`Determine a rank indicative of
`the numberof transport blocks
`to send for the data transmission
`
`Form a report based on
`the PCI, rank and COI
`
`Send the report to the transmitter
`
`714
`
`716
`
`718
`
`720
`
`FIG. 7
`
`FIG. 8
`
`8
`
`

`

`US 8,699,587 B2
`
`1
`FEEDBACK OF PRECODING CONTROL
`
`INDICATION (PCT AND CHANNEL QUALITY
`INDICATION (CQD IN A WIRELESS
`COMMUNICATION SYSTEM
`
`CLAIM OF PRIORITY UNDER 35 U.S.C. §119
`
`The present Application for Patent claims priority to Pro-
`visional Application Ser. No. 60/838,677, entitled “Joint Sig-
`naling of Precoding Control Information and Channel Qual-
`ity Indicators in a Cellular MIMO System,” filed Aug. 18,
`2006, assignedto the assignee hereof, and expressly incorpo-
`rated herein by reference.
`
`BACKGROUND
`
`I. Field
`
`Thepresentdisclosure relates generally to communication,
`and more specifically to techniques for sending feedback
`information in a wireless communication system.
`II. Background
`In a wireless communication system, a transmitter may
`utilize multiple (T) transmit antennasfor data transmission to
`a receiver equipped with multiple (R) receive antennas. The
`multiple transmit and receive antennas form a multiple-input
`multiple-output
`(MIMO) channel
`that may be used to
`increase throughput and/or improvereliability. For example,
`the transmitter may transmit up to T data streams simulta-
`neously from the T transmit antennas to improve throughput.
`Alternatively,
`the transmitter may transmit a single data
`stream from all T transmit antennas to improve reception by
`the receiver. Each data stream may carry one transport block
`or packet of data in a given transmission time interval (TTI).
`Hence,the terms “data stream”and“transport block” may be
`used interchangeably.
`Good performance (e.g., high throughput) may be
`achieved by precoding one or more data streams with a pre-
`coding matrix selected based on the response of the MIMO
`channel from the transmitter to the receiver. Precoding may
`also be referred to as beamforming,spatial mapping, etc. The
`receiver may evaluate different possible precoding matrices
`and select a precoding matrix as well as the numberofdata
`streams to send such that the best performance can be
`achieved. The receiver may also determine a signal-to-inter-
`ference-and-noise ratio (SINR)for each possible data stream
`and select a data rate for the data stream based on the SINR.
`The receiver may send feedback information that may include
`the selected precoding matrix, the data rate for each data
`stream, etc. The transmitter may process one or more data
`streams in accordance with the feedback information and
`
`send the data stream(s) to the receiver.
`The feedback information may improve data transmission
`performance. However, valuable radio resources are con-
`sumedto send the feedback information. There is therefore a
`
`needin the art for techniquesto efficiently send the feedback
`information.
`
`SUMMARY
`
`Techniques for efficiently sending feedback information in
`a wireless communication system are described herein. The
`feedback information may comprise precoding control indi-
`cation (PCI), rank, channel quality indication (CQI), etc., or
`any combination thereof.
`In one design of sending feedback information, PCI, rank
`and CQIfor data transmission from a transmitter to a receiver
`may be determined, e.g., by evaluating different hypotheses
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`and selecting the PCI, rank and CQI ofthe hypothesis with the
`best performance. A report may be formed based on the
`selected PCI, rank and CQI. The rank mayindicate the num-
`ber of transport blocks to send in parallel for the data trans-
`mission. The PC] may comprise a precoding matrix or vector
`to use for precodingat least one transport block to send for the
`data transmission. The CQI may comprise at least one CQI
`value for the at least one transport block. Each CQI value may
`be associated with parameters for processing a transport
`block, e.g.,
`transport block size, coding and modulation
`scheme, numberof channelization codes, etc. The rank and
`CQI may be combined based on a mapping. For example, the
`CQI may comprise one CQIvalue andfall within a first range
`ofvalues(e.g., from 0 to 30) ifone transport block is preferred
`by the receiver. The CQI may comprise two CQI values and
`fall within a second range of values(e.g., from 31 to 255) if
`twotransport blocksare preferred.
`In one design of sending data transmission, a report com-
`prising PCI, rank and CQI maybereceived by a transmitter.
`The numberoftransport blocks to send for the data transmis-
`sion may be determined based on one of multiple ranges of
`values within which the CQIfalls. At least one transport block
`maybe processed (e.g., encoded and modulated) based on at
`least one CQI value from the CQI and maybe further pre-
`coded based on a precoding matrix or vector from the PCI.
`Various aspects and features ofthe disclosure are described
`in further detail below.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 shows a wireless communication system.
`FIG. 2 showsa block diagram of a Node B and a UE.
`FIG. 3 showsa timing diagram for a set of physical chan-
`nels.
`
`FIG.4 showsa design ofmapping two CQIvalues to a CQI
`combination.
`
`FIG. 5 showsa design of sending the PCI, rank and CQI on
`an HS-DPCCH.
`
`FIG. 6 showsa design of sending the PCI and rank on an
`uplink DPCCH.
`FIG. 7 showsa design of a process for sending feedback
`information.
`FIG. 8 shows a design of a process for sending data trans-
`mission.
`
`DETAILED DESCRIPTION
`
`The techniques described herein may be used for various
`wireless communication systems such as Code Division Mul-
`tiple Access (CDMA) systems, Time Division Multiple
`Access (TDMA) systems, Frequency Division Multiple
`Access (FDMA) systems, Orthogonal FODMA (OFDMA)
`systems, Single-Carrier FOMA (SC-FDMA) systems, etc.
`The terms “system” and “network” are often used inter-
`changeably. A CDMA system may implementa radio tech-
`nology such Universal Terrestrial Radio Access (UTRA),
`cdma2000, etc. UTRA includes Wideband-CDMA (which
`covers W-CDMA, UMTS-FDD) and Time Division Synchro-
`nous CDMA (TD-SCDMA)(which covers UMTS-TDD,low
`chip rate UMTS-TDD,and high chip rate UMTS-TDD).
`cdma2000 covers IS-2000, IS-95 and IS-856 standards. A
`TDMA system may implementa radio technology such as
`Global System for Mobile Communications (GSM). An
`OFDMA system may implement a radio technology such as
`Evolved UTRA (E-UTRA), Ultra Mobile Broadband
`(UMB),
`IEEE 802.20,
`IEEE 802.16 (WiMAX), Flash-
`OFDM®, etc. UTRA and E-UTRA are part of Universal
`
`9
`
`

`

`US 8,699,587 B2
`
`4
`provide samples to a channel processor 268 and an equalizer/
`CDMA demodulator (Demod) 260. Processor 268 may
`derive coefficients for a front-end filter/equalizer and coeffi-
`cients for one or more combiner matrices. Unit 260 may
`perform equalization with the front-end filter and COMA
`demodulation and mayprovide filtered symbols. A MIMO
`detector 262 may combinethe filtered symbols across spatial
`dimension and provide detected symbols, which are estimates
`of the data symbols and signaling symbols sent to UE 120.A
`receive (RX) data processor 264 may process (e.g., symbol
`demap, deinterleave, and decode) the detected symbols and
`provide decoded data and signaling. In general, the process-
`ing by equalizer/CDMA demodulator 260, MIMO detector
`262, and RX data processor 264 is complementary to the
`processing by CDMA modulator 216, spatial mapper 214,
`and TX data and signaling processor 212, respectively, at
`Node B 110.
`
`Channel processor 268 may estimate the response of the
`wireless channel from Node B 110 to UE 120. Processor 268
`
`and/or 270 mayprocess the channel estimate to obtain feed-
`back information, which may comprise the information
`shown in Table 1.
`
`TABLE 1
`
`Info Description
`
`PCI
`
`Convey a specific precoding matrix or vector to use for precoding
`one or more transport blocks.
`Rank Indicate the numberoftransport blocks to sendin parallel.
`CQI
`Conveyprocessing parameters for each transport block.
`
`Processor 268 and/or 270 may jointly determine the PCI,
`rank and CQI for downlink data transmission based on the
`channel estimate. For example, processor 268 and/or 270 may
`evaluate different possible precoding matrices that can be
`usedfor data transmission and different combinations of col-
`
`20
`
`25
`
`30
`
`35
`
`3
`Mobile Telecommunication System (UMTS). Long Term
`Evolution (LTE) is an upcoming release of UMTSthat uti-
`lizes E-UTRA. UTRA, E-UTRA, UMTS, LTE and GSM are
`described in documents from an organization named “3rd
`Generation Partnership Project” (@GPP). cdma2000 is
`described in documents from an organization named “3rd
`Generation Partnership Project 2” (3GPP2). These various
`radio technologies and standards are known in the art. For
`clarity, certain aspects of the techniques are described below
`for UMTS, and 3GPP terminology is used in much ofthe
`description below.
`FIG. 1 showsa wireless communication system 100 with
`multiple Node Bs 110 and user equipments (UEs) 120. Sys-
`tem 100 may also be referred to as a Universal Terrestrial
`Radio Access Network (UTRAN) in 3GPP. A Node B is
`generally a fixed station that communicates with the UEs and
`mayalso be referred to as an evolved Node B (eNode B), a
`base station, an access point, etc. Each Node B 110 provides
`communication coveragefor a particular geographic area and
`supports communication for the UEs located within the cov-
`erage area. A system controller 130 couples to Node Bs 110
`and provides coordination and control for these Node Bs.
`System controller 130 may be a single network entity or a
`collection of network entities.
`
`UEs 120 maybe dispersed throughoutthe system, and each
`UE maybestationary or mobile. A UE mayalso be referred to
`as a mobile station, a terminal, an access terminal, a sub-
`scriber unit, a station, etc. A UE may be a cellular phone, a
`personal digital assistant (PDA), a wireless device, a hand-
`held device, a wireless modem, a laptop computer,etc.
`FIG. 2 showsa block diagram of a design of one Node B
`110 and one UE 120.
`Node B 110 is equipped with multiple (T) antennas 220a
`through 220¢ that may be used for data transmission on the
`downlink and data reception on the uplink. UE 120 is
`equipped with multiple (R) antennas 252a through 252rthat
`may be used for data transmission on the uplink and data
`reception on the downlink. Each antenna maybe a physical
`antenna,a virtual antenna comprising an antennaarray and an
`appropriate beamforming device, an antenna array with a
`fixed weighting network, etc. A MIMOtransmission may be
`sent from the T transmit antennas at Node B 110 to the R
`receive antennas at UE 120.
`
`umns in each precoding matrix. Each column of a precoding
`matrix may be used for precoding/spatial mapping to send
`one transport block from all T antennas 220a through 220r.
`Processor 268 and/or 270 may select a precoding matrix as
`well as one or more specific columnsofthe selected precod-
`ing matrix that can provide the best performance. Perfor-
`mance may be quantified by throughput and/or some other
`metric. The PCI may convey the selected precoding matrix,
`At Node B 110, a transmit (TX) data and signaling proces-
`the selected column(s) of the selected precoding matrix, etc.
`sor 212 mayreceive data from a data source (not shown) for
`The CQI may convey the coding and modulation scheme to
`all scheduled UEs. Processor 212 may process(e.g., format,
`use for each transport block, the data rate or transport format
`encode, interleave, and symbol map)the data for each UE and
`for each transport block, the SINR of each transport block,
`provide data symbols, which are modulation symbols for
`etc. Processor 268 and/or 270 may provide feedback infor-
`data. Processor 212 mayalso process signaling and provides
`mation, which may include the PCI, rank and CQI.
`signaling symbols, which are modulation symbols for signal-
`ing. A spatial mapper 214 may precode the data symbols for
`The feedback information and data to send on the uplink
`
`each UE based onaprecoding matrixor vector selected by/for maybe processed by a TX data and signaling processor 280,
`that UE andprovide output symbols. In general, a matrix may
`further processed by a COMA modulator 282, and condi-
`have a single column or multiple columns. A CDMA modu-
`tioned by transmitters 254a through 254to generate R uplink
`lator (Mod) 216 may perform CDMA processing on the out-
`signals, which maybe transmitted via antennas 252a through
`put symbols and signaling symbols and may provide T output
`252r, respectively. The number of transmit antennas at UE
`chip streams to T transmitters (TMTR) 218a through 2187.
`120 may be the sameas or different from the number of
`Each transmitter 218 may process (e.g., convert to analog,
`receive antennas, e.g., UE 120 may transmit the feedback
`filter, amplify, and frequency upconvert) its output chip
`information using one antenna and receive data using two
`stream and generate a downlink signal. T downlink signals
`antennas. At Node B 110, the uplink signals from UE 120 may
`from T transmitters 218a@ through 2187 may be sent via T
`be received by antennas 220a through 2207, conditioned by
`antennas 220a through 220+, respectively.
`receivers 218a through 218z,filtered by an equalizer/CDMA
`At VE 120, R antennas 252a through 2527 may receive the
`demodulator 240, detected by a MIMO detector 242, and
`downlink signals from Node B 110 and provide R received
`processed by an RX data and signaling processor 244 to
`signals to R receivers (RCVR) 254a through 254r, respec-
`recover the feedback information and data sent by UE 120.
`tively. Each receiver 254 mayprocess (e.g., filter, amplify,
`Controllers/processors 230 and 270 may direct the opera-
`frequency downconvert, and digitize) its received signal and
`tion at Node B 110 and UE 120, respectively. Memories 232
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`5
`and 272 may store program codes and data for Node B 110
`and UE 120, respectively. A scheduler 234 may schedule UEs
`for downlink and/or uplink transmission, e.g., based on the
`feedback information received from the UEs.
`In UMTS, data for a UE may beprocessed as one or more
`transport channels at a higher layer. The transport channels
`may carry data for one or moreservices, e.g., voice, video,
`packet data, etc. The transport channels may be mapped to
`physical channels at a physical layer. The physical channels
`may be channelized with different channelization codes and
`maythus be orthogonalto one another in the code domain.
`3GPP Release 5 and later supports High-Speed Downlink
`Packet Access (HSDPA), which is a set of channels and
`procedures that enable high-speed packet data transmission
`on the downlink. For HSDPA, a Node B maysend data on a
`High Speed Downlink Shared Channel (HS-DSCH), which is
`a downlink transport channelthat is shared by all UEsin both
`time and code. The HS-DSCH maycarry data for one or more
`UEsin each TTI. For HSDPA,a 10 millisecond (ms) frameis
`partitionedinto five 2-ms subframes, each subframeincludes
`three slots, and each slot has a duration of 0.667 ms. A TTIis
`equal to one subframe for HSDPA andis the smallest unit of
`time in which a UE maybe scheduled and served. The sharing
`of the HS-DSCH maybe dynamic and may change from TTI
`to TTI.
`
`Table 2 lists some downlink and uplink physical channels
`in UMTSandprovides a short description for each physical
`channel.
`
`20
`
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`
`6
`uplink DPCCH butis aligned to a 256-chip raster so that the
`uplink transmit signals on different code channels remain
`orthogonal.
`Node B 110 may perform precoding/spatial mapping for
`each HS-PDSCH channelization code ¢ in each symbol
`period s, as follows:
`a{s)-B, bs),
`
`Eq (1)
`
`whereb,(s) is a vector with up to T data symbols to send with
`channelization code c in symbolperiods,
`B, is a precoding matrix or vector for channelization code
`c, and
`d_(s) is a vector with T output symbols to send with chan-
`nelization code c in symbolperiod s via the T transmit
`antennas.
`
`Various precoding/spatial mapping schemes may be sup-
`ported such as double-transmit adaptive array (D-TxAA),
`space-time transmit diversity (STTD), closed loop transmit
`diversity (CLTD), per antenna rate control (PARC), code
`reuse Bell Labs layered space-time (CRBLAST), etc. For
`D-TxAA,onetransport block may be sent from two antennas
`using a 2x1 precoding vector, or two transport blocks may be
`sent from two antennas using a 2x2 precoding matrix. For
`STTD,one transport block may be sent from two transmit
`antennas, with each data symbol being sent from both anten-
`nas in two symbolperiods to achieve time and spatial diver-
`sity. For CLTD, one transport block may be sent from two
`transmit antennas, with the phase of one antenna being
`
`Link
`
`Channel
`
`Channel Name
`
`Description
`
`TABLE 2
`
`Downlink
`
`Downlink
`
`Uplink
`
`Uplink
`
`Uplink
`
`HS-SCCH
`
`Carry data sent on the
`HS-PDSCH High Speed Physical
`HS-DSCHfordifferent UEs.
`Downlink Shared Channel
`Carry signaling for the
`Shared Control
`HS-PDSCH.
`Channel for HS-DSCH
`HS-DPCCH Dedicated Physical Control Carry feedback for downlink
`Channel for HS-DSCH
`transmission in HSDPA.
`Dedicated Physical
`Carry data sent by a UE toa
`Data Channel
`Node B onthe uplink.
`Dedicated Physical
`Carry control information
`Control Channel
`sent by the UE to the Node B.
`
`DPDCH
`
`DPCCH
`
`FIG. 3 showsa timing diagram for the physical channels in
`Table 2. For HSDPA, a Node B mayserve one or more UEsin
`each TTI. The Node B sendssignaling for each scheduled UE
`on the HS-SCCH andsends data on the HS-PDSCHtwoslots
`
`later. The Node B may use a configurable numberof 128-chip
`channelization codes for the HS-SCCH and may use up to
`fifteen 16-chip channelization codes for the HS-PDSCH(s).
`Each UE that might receive data on the HS-PDSCH may
`process a number of HS-SCCH(s) in each TTI to determine
`whether signaling has been sent for that UE. Each UEthatis
`scheduled in a given TTI may process the HS-PDSCH to
`recover data sent to that UE. Each scheduled UE may send
`either an acknowledgement (ACK) on the HS-DPCCHif a
`transport block is decoded correctly or a negative acknow]-
`edgement (NACK)otherwise. Each UE mayalso send feed-
`back information to the Node B on the HS-DPCCH and/or
`
`uplink DPCCH,as described below.
`FIG. 3 also shows timing offsets between the uplink
`DPCCH,the HS-PDSCH,and the HS-DPCCHatthe UE. The
`HS-PDSCHstarts two slots after the HS-SCCH. The HS-
`
`DPCCHstarts approximately 7.5 slots from the end of the
`corresponding transmission on the HS-PDSCH and also
`mx256 chips after the start of a corresponding uplink DPCH
`subframe. The HS-DPCCH may be asynchronous to the
`
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`
`adjusted to improve reception by the UE. For PARC, up to T
`transport blocks may be sent from up to T transmit antennas,
`one transport block per antenna. For CRBLAST, onetrans-
`port block may be sent from up to T transmit antennas. For
`both PARC and CRBLAST,precoding matrix B. may be an
`identity matrix I containing ones along the diagonaland zeros
`elsewhere. Other spatial mapping schemes mayalso be sup-
`ported.Forclarity, the following description assumes the use
`of D-TxAA, and feedback information is generated and sent
`for D-TxAA.
`
`In general, any numberof precoding matrices may be sup-
`ported for D-TxAA.In one design, two precoding matrices
`55 are supported and defined as follows:
`
`1
`1
`1
`Wea Vo sth piSal4
`and
`
`Eq (2)
`
`1
`
`1
`
`1
`
`W= Vr |soo elma }
`
`The two columnsofeach precoding matrix are orthogonal to
`one another, and each column has unit power.
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`US 8,699,587 B2
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`7
`Four precoding vectors may be defined based on precoding
`matrices W, and W, and maybe given as:
`
`1
`Wo =a: eirl4
`
`1
`
`m=O) ina |:
`
`Eq (3)
`
`1
`
`| and w; =a- |- }
`
`1
`
`where w, and W,are precoding vectors corresponding to the
`first and second columns, respectively, of precoding matrix
`W,, or W,=|Wo wa],
`w, and w, are precoding vectors correspondingto the sec-
`ondandfirst columns, respectively, of precoding matrix
`W,, or W,=[w,w,], and a=1/V2.
`Since the first element of each precoding vector has a
`commonvalue ofo=1/V2,the four precoding vectors in equa-
`tion (3) may be defined based on the values of the second
`element, which maybe given as:
`
`1l+j
`z
`
`1-j
`MLE
`
`;
`
`WwW=
`
`-l+j
`2
`
`wo =
`
`and w3
`
`-l-j
`2
`
`>
`
`Eq (4)
`
`8
`selected precoding matrix or vector. The UE may determine
`the rank for the best hypothesis, which may indicate the
`numberoftransport blocks to send in parallel. The UE may
`also determine a CQI value for each transport block, which
`may convey processing parameters for the transport block.
`The UE may send the PCI, rank and CQI as feedback infor-
`mation to the Node B.
`
`In one design, the PCI conveys the selected precoding
`matrix and may be sent with one PCIbit defined as shown in
`Table 3.
`
`TABLE 3
`
`PCI value
`
`Selected precoding matrix
`
`0
`1
`
`Ww,
`W
`
`In another design, the PCI conveys the selected precoding
`matrix and which column ofthe selected precoding matrix to
`use if sending onetransport block. In this design, the PCI and
`rank maybe sent with three PCI bits defined as shown in Table
`4.
`
`TABLE 4
`
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`
`25
`
`PCI value
`
`Selected precoding
`matrix
`
`Numberof
`transport blocks
`
`Selected column
`for single
`transport block
`
`where Wo, W,, W> and w, are the second elementof precoding
`vectors W,, W,, W, and w;, respectively.
`The UE mayperiodically determine the precoding matrix
`1 (or Wo)
`1
`Ww,
`0
`or vectorthat can provide the best performance for downlink
`2 (or w3)
`1
`Ww,
`1
`data transmission to the UE. For example, in each TTI, the UE
`1 (or w2)
`1
`WwW,
`2
`3
`WwW
`1
`2 (or w,)
`mayestimate the response of the wireless channel from the
`4
`WwW,
`2
`NA
`NodeBto the UE. The UE maythen evaluate the performance
`5
`WwW
`2
`NA
`of different hypotheses corresponding to different possible
`precoding matrices and vectors. For example, the UE may
`determine the overall throughput for transmission of (1) two
`transport blocks using W,, (2) two transport blocks using W,,
`(3) one transport block using wo, (4) one transport block using
`w_, (5) one transport block using w,, (6) one transport block
`using w;, etc. As part of the throughput computation for each
`hypothesis, the UE may determine the SINRofeach transport
`block based on the precoding matrixor vectorfor that hypoth-
`esis.
`
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`40
`
`In yet another design, the PCI conveysthe selected precod-
`ing matrix, which column ofthe selected precoding matrix to
`use if sending one transport block, and whichtransport block
`will be decoded first (which is called the master transport
`block) ifthe UE supports SIC. In this design, the PCI and rank
`may be sent with three PCIbits defined as shown in Table 5.
`PCI values 011 and 111 may be used by SIC-capable UEs.
`
`The UE maysupport successive interference cancellation
`(SIC) and may recover multiple transport blocks using SIC.
`Selected
`Index of
`column
`For SIC, the UE mayprocess the received samples to recover
`master
`for
`a first (or master) transport block, estimate the interference
`
`Selected Numberof_single transport
`due to the recovered transport block, subtract the estimated
`PCIvalue
`precoding
`transport
`transport
`block for SIC
`interference from the received samples, and recover a second
`transport block in the same manner. Thefirst transport block
`observes interference from the second transport block and
`may thus achieve lower SINR. The second transport block
`mayobservelittle interference from the first transport block,
`if the interference cancellation was effective, and may
`achieve higher SINR.
`Ifthe UE supports SIC, then the UE may determineoverall
`throughputfor transmission oftwotransport blocks using W,
`with (i) the transport block sent with the first column of W,
`recovered first and (i1) the transport block sent with the sec-
`ond column of W,recovered first. The UE may also deter-
`mine overall throughput for transmission of two transport
`blocks using W, with (i) the transport block sent with the first
`column of W, recoveredfirst and (ii) the transport block sent
`with the second column of W, recoveredfirst.
`The UE mayselect the precoding matrix or vector that can
`provide the best performance among all hypotheses evalu-
`ated. The UE maythen determine PCI, which may convey the
`
`TABLE 5
`
`PCI,
`
`PCI, PCI
`
`matrix
`
`blocks
`
`block
`
`capable UE
`
`0
`0
`0
`0
`1
`1
`1
`1
`
`0
`0
`1
`1
`0
`0
`1
`1
`
`0
`1
`0
`1
`0
`1
`0
`1
`
`WwW,
`WwW,
`WwW,
`WwW,
`WwW
`WwW,
`WwW
`WwW
`
`1
`2
`1
`2
`1
`2
`1
`2
`
`1
`NA
`2
`NA
`1
`NA
`2
`NA
`
`NA
`1
`NA
`2
`NA
`1
`NA
`2
`
`In general, the PCI may comprise any information that can
`convey a specific precoding matrix or vector to use for data
`transmission. In the designs described above, the PCI may
`conveythe selected preceding matrix and the selected column
`of this matrix if only one transport block is sent. In another
`design, the PCI] may convey one or more specific precoding
`vectors to use for one or more transport blocks, and additional
`precoding vectors to use for additional transport blocks, if
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`any, may be determined based on the signaled precoding
`vector(s). For example, in the design shown in equations (2)
`and (3), the PC] may convey a specific preceding vectorto use
`for one transport block. Iftwotransport blocks are selected or
`preferred by the UE,then the precoding vector to use for the 5
`second transport block may be the complementofthe sig-
`naled precoding vector, with both vectors being from the
`same precoding matrix. For example, a 2-bit PC] value may
`convey precoding vector w, for one transport block. If two
`transport block are selected or preferred, then the comple-
`mentary precoding vector w, may be used for the second
`transport block, with both w, and w, being from W,. In
`general, the numberofbits to use for the PCI may be reduced
`by exploiting the structure of the precoding matrices, so that
`some precoding information may be sent