(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2008/0108310 A1
`
`(43) Pub. Date:
`May 8, 2008
`Tong et al.
`
`US 20080108310A1
`
`(54) CLOSED LOOP MIMO SYSTEMS AND
`METHODS
`
`Related US. Application Data
`
`(76)
`
`Inventors: Wen Tong, Ottawa (CA); Ming Jia,
`Ottawa (CA); Jianglei Ma, Kanata (CA);
`Peiying Zhu, Kanata (CA); Hua Xu,
`Nepean (CA); Dong-Sheng Yu, Ottawa
`(CA); Hang Zhang, Nepean (CA);
`Mo-Han Fong, L’Original (CA)
`
`Correspondence Address:
`SMART & BIGGAR
`PO. BOX 2999, STATION D
`900-55 METCALFE STREET
`
`OTTAWA, ON K1P5Y6 (CA)
`
`(21) Appl. No.:
`
`11/630,391
`
`(22) PCT Filed:
`
`Jun. 22, 2005
`
`(86) PCT No.:
`
`PCT/CA05/00958
`
`§ 371(c)(1):
`(2), (4) Date:
`
`Dec. 22, 2006
`
`(60) Provisional application No. 60/581,356, filed on Jun.
`22, 2004. Provisional application No. 60/582,298,
`filed on Jun. 24, 2004. Provisional application No.
`60/601,178, filed onAug. 13, 2004. Provisional appli-
`cation No. 60/614,621, filed on Sep. 30, 2004. Provi-
`sional application No. 60/619,461, filed on Oct. 15,
`2004. Provisional application No. 60/642,697, filed on
`Jan. 10, 2005.
`
`Publication Classification
`
`(51)
`
`Int. Cl.
`(2006.01)
`H04B 1/00
`(52) U.S.Cl.
`................................................................ 455/69
`
`(57)
`
`ABSTRACT
`
`Systems and methods for closed loop MIMO (multiple input
`and multiple output) wireless communication are provided.
`Various transmit formats including spatial multiplexing and
`STTD are defined in which vector or matrix weighting is
`employed using information fed back from receivers. The
`feedback information may include channel matrix or SVD-
`based feedback.
`
`FDlme
`VT
`
`1 Measure MIMI]
`1
`ChanneIH
`
`
`Measure MINID
`(31132113ng
`
`
`206
`
`SVD
`
`
`
`
`Beam
`
`
`
`
`MIME) Feedback
`
`
`Reconstruct H
`Channel
`
`Eli
`2.15
`
`
`
`
`
`
`AMGlEiucn
`Ell! Feedback
`
`Assignment
`Channel
`
`
`m.
`2E
`
`
`
`
`
`
`HUAWEI 1005
`
`1
`
`HUAWEI 1005
`
`

`

`Patent Application Publication May 8, 2008 Sheet 1 0f 42
`
`US 2008/0108310 A1
`
`
`
`’ FIG. 1
`
`2
`
`

`

`Patent Application Publication May 8, 2008 Sheet 2 0f 42
`
`US 2008/0108310 A1
`
`14\
`
`
`
`
`
`'
`Transmit Circuitry
`3333:353er
`Netvylnlrsklinnggiface
`
`
`
`
`
`err
`2.2.
`2‘4
`
`
`
`
`
`
`
`Receive Circuitry
` Control System
`
`
`gfi
`fl
`
`
`
`/
`
`528
`
`FIG. 2
`
`40
`
`Receive Circuitry
`3.8.
`
`,._....._...__..<....,........__.
`
`Transmit Circuitry
`E
`
`i........'.....
`
`
`
`
`
`Cnniroi Sysiem
`3353523
`
`
`34
`:2
`
`
`
`
`
`Interface Circuitry
`Q.
`
`
`FIG. 3
`
`3
`
`

`

`Patent Application Publication May 8, 2008 Sheet 3 0f 42
`
`US 2008/0108310 A1
`
`
`
`4
`
`

`

`Patent Application Publication
`
`May 8, 2008 Sheet 4 of 42
`
`US 2008/0108310 A1
`
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`

`

`Patent Application Publication May 8, 2008 Sheet 5 0f 42
`
`US 2008/0108310 A1
`
`r110
`
`
`
`184
`
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`
`User #1
`
`Userl#2
`
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`
`158
`
`160
`
`162
`
`6
`
`

`

`Patent Application Publication May 8, 2008 Sheet 6 0f 42
`
`US 2008/0108310 A1
`
`
`
`Antenna Grouping in DFDM Symbol.
`
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`
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`
`

`

`Patent Application Publication May 8, 2008 Sheet 7 0f 42
`
`US 2008/0108310 A1
`
`134\
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`Patent Application Publication May 8, 2008 Sheet 8 0f 42
`
`US 2008/0108310 A1
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`Patent Application Publication May 8, 2008 Sheet 9 0f 42
`
`US 2008/0108310 A1
`
`Antenna Grouping
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`FIG. 13
`
`10
`
`10
`
`
`

`

`Patent Application
`
`Publication May 8, 2008 Sheet 10 of 42
`
`US 2008/0108310 A1
`
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`Patent Application Publication May 8, 2008 Sheet 11 0f 42
`
`US 2008/0108310 A1
`
`Antenna
`
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`
`12
`
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`
`

`

`Patent Application
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`May 8
`
`2008 Sheet 12 of 42
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`US 2008/0108310 A1
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`Patent Application Publication May 8, 2008 Sheet 13 0f 42
`
`US 2008/0108310 A1
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`

`Patent Application Publication May 8, 2008 Sheet 14 0f 42
`
`US 2008/0108310 A1
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`

`Patent Application Publication May 8, 2008 Sheet 15 0f 42
`
`US 2008/0108310 A1
`
`Ugtinn 2
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`Patent Application Publication May 8, 2008 Sheet 16 0f 42
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`US 2008/0108310 A1
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`Patent Application Publication May 8, 2008 Sheet 17 0f 42
`
`US 2008/0108310 A1
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`Patent Application Publication May 8, 2008 Sheet 18 0f 42
`
`US 2008/0108310 A1
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`
`19
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`

`Patent Application Publication May 8, 2008 Sheet 19 0f 42
`
`US 2008/0108310 A1
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`

`Patent Application Publication May 8, 2008 Sheet 20 0f 42
`
`US 2008/0108310 A1
`
`Nnn Pre-nnded Channel H for:
`
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`
`21
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`

`

`Patent Application Publication May 8, 2008 Sheet 21 of 42
`
`US 2008/0108310 A1
`
`
`
`FIG. 25
`
`22
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`
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`
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`

`Patent Application Publication May 8, 2008 Sheet 23 0f 42
`
`US 2008/0108310 A1
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`Patent Application Publication May 8, 2008 Sheet 24 0f 42
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`US 2008/0108310 A1
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`FIG. 28
`
`25
`
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`

`Patent Application Publication May 8, 2008 Sheet 25 0f 42
`
`US 2008/0108310 A1
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`
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`
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`
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`
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`
`® Pilot Carrier for M831 (Ant 3) ® Pilot Carrier for M332 (Ant 3)
`
`FIG. 29
`
`26
`
`26
`
`

`

`Patent Application Publication May 8, 2008 Sheet 26 0f 42
`
`US 2008/0108310 A1
`
`
`
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`
`545% Pilot Carrier for M331 (Ant1) 547E PilntflarrierfnrMSSZ{AnH}
`
`FIG. 30
`
`27
`
`27
`
`

`

`Patent Application Publication May 8, 2008 Sheet 27 0f 42
`
`US 2008/0108310 A1
`
`Time
`
`Frequency
`
`
`5300.00.00023
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`
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`M332 (Ant 3)
`
`FIG. 31
`
`28
`
`28
`
`

`

`Patent Application Publication May 8, 2008 Sheet 28 0f 42
`
`US 2008/0108310 A1
`
`600
`
`602
`
`Beam—Farmer
`
`Feedback
`
`Feedback
`
`
`
`MIMDISTC
`
`Beam—Former
`
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`
`
`
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`
`
`
`
`
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`
`FIG. 32
`
`29
`
`29
`
`

`

`Patent Application Publication May 8, 2008 Sheet 29 0f 42
`
`US 2008/0108310 A1
`
`SVD with
`Beamformer
`
`Use Power to
`Transmit on Strong
`Eigen Modes
`
`Discard Weak
`
`'
`
`Eigen Modes
`
`Serent Best Group
`Antenna with
`Power Boosting
`
`Antennas
`
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`
`FIG. 34
`
`30
`
`30
`
`

`

`Patent Application Publication May 8, 2008 Sheet 30 0f 42
`
`US 2008/0108310 A1
`
`+ AS—1
`
`— svn 53-1
`
`v 3V0 Performance
`
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`FIG. 35~
`
`31
`
`31
`
`

`

`Patent Application Publication May 8, 2008 Sheet 31 0f 42
`
`US 2008/0108310 A1
`
`VB L1 OSVD L'l
`
`IVB L2 xSVD L2 *VB L3 OSVD L3
`
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`
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`
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`FIG. 36
`
`32
`
`32
`
`

`

`Patent Application Publication May 8, 2008 Sheet 32 0f 42
`
`US 2008/0108310 A1
`
`
`
`
`
`
`Measure MIMD
`5"- Measure MIMI]
`Channel H
`Channel H
`
`
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`gm
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`FIG. 37
`
`33
`
`33
`
`

`

`Patent Application Publication May 8, 2008 Sheet 33 0f 42
`
`US 2008/0108310 A1
`
`
`Measure MIMD
`Differential
`Channel H
`Encoding of H
`
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`15$
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`FIG. 38
`
`34
`
`34
`
`

`

`Patent Application Publication May 8, 2008 Sheet 34 0f 42
`
`US 2008/0108310 A1
`
`Input
`
`250
`
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`
`
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`
`35
`
`35
`
`

`

`Patent Application Publication May 8, 2008 Sheet 35 0f 42
`
`US 2008/0108310 A1
`
`
`
`Measure MIMI]
`Channel H
`3%
`
`
`
`
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`w
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`
`36
`
`36
`
`

`

`Patent Application Publication May 8, 2008 Sheet 36 0f 42
`
`US 2008/0108310 A1
`
`Feedback Requirement (NxN MIMU)
`
`‘
`
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`
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`114.29%
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`
`37
`
`37
`
`

`

`Patent Application Publication May 8, 2008 Sheet 37 0f 42
`
`US 2008/0108310 A1
`
`
`
`
`Measure MIMU
`Channel H
`.
`32E
`
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`FIG. 43
`
`38
`
`38
`
`

`

`Patent Application Publication May 8, 2008 Sheet 38 0f 42
`
`US 2008/0108310 A1
`
`352
`
`350
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`
`39
`
`39
`
`

`

`Patent Application Publication May 8, 2008 Sheet 39 0f 42
`
`US 2008/0108310 A1
`
`
`
`
`Measure MIME)
`1‘1
`Channex H
`
`
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`FIG. 45
`
`40
`
`40
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`

`

`Patent Application Publication May 8, 2008 Sheet 40 0f 42
`
`US 2008/0108310 A1
`
`Symbol—0
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`
`FIG. 46
`
`41
`
`41
`
`

`

`Patent Application Publication May 8, 2008 Sheet 41 0f 42
`
`US 2008/0108310 A1
`
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`

`Patent Application Publication May 8, 2008 Sheet 42 0f 42
`
`US 2008/0108310 A1
`
`Space Time Ending Matrix Set
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`43
`
`43
`
`

`

`US 2008/0108310 A1
`
`May 8, 2008
`
`CLOSED LOOP MIMO SYSTEMS AND METHODS
`
`RELATED APPLICATIONS
`
`
`
`[0001] This application claims the benefit of US. Provi—
`sional Patent Application No. 60/581,356 filed on Jun. 22,
`2004, US. Provisional patent Application No. 60/582,298
`filed on Jun. 24, 2004, US. Provisional Patent Application
`No. 60/601,178 filed on Aug. 13, 2004, Provisional Patent
`Application No. 60/514,621 filed on Sep. 30, 2004, Provi—
`sional Patent Application No. 60/619,461 filed on Oct. 15,
`2004 and Provisional PatentApplication N o. 60/642,697 filed
`on Jan. 10, 2005, all of which are hereby incorporated by
`reference in their entirety.
`
`FIELD OF THE INVENTION
`
`[0002] The invention relates to MIMO (multiple input,
`multiple output) systems and methods.
`
`BACKGROUND OF THE INVENTION
`
`In MIMO (multiple input multiple output) OFDM
`[0003]
`(orthogonal frequency division multiplexing) systems, there
`are multiple transmit antennas and multiple receive antelmas
`and a plurality of sub-carriers that are available for transmis-
`sion between the transmit antennas and the receive antennas
`for either one or multiple users. New advances in MIMO
`OFDM systems are taught in Applicant’s co-pending appli-
`cation <attomey docket 71493—1320> entitled “Pilot Design
`For OFDM Systems With Four transmitAntennas” filed Mar.
`15, 2005, and in Applicant’s co-pending application <attor-
`ney docket 714934330) entitled “Wireless Communication
`Methods, Systems, And Signal Structures” filedApr. 4, 2005,
`both hereby incorporated by reference in their entirety. With
`open loop implementations, the transmitter transmits on the
`multiple transmitter antennas and sub-carriers without the
`benefit of channel information fed back from the receivers.
`
`[0004] Efforts have been made to facilitate wireless closed-
`loop MIMO communications including broadband closed-
`loop MIMO, which might for example be based on OFDM
`modulation schemes, and narrowband closed-loop MIMO.
`Broadband closed—loop MIMO includes many sub—bands.
`Each of these sub-bands requires MTMO channel feedback
`for a closed-loop implementation. As a result the feedback
`resources required for broadband closed-loop MIMO can
`become quite large. Narrowband closed—loop MIMO, by
`comparison, includes one or a few sub—bands and requires a
`relatively smaller amount of feedback resources. Broadband
`and narrowband MIMO, therefore, have different applica-
`tions.
`
`SUMMARY OF TIIE INVENTION
`
`[0005] According to one broad aspect, the invention pro—
`vides a MIMO system comprising: a transmitter having mul-
`tiple transmit antennas; at least one receiver, each receiver
`having at least one receive antenna; each receiver being
`adapted to transmit at least one type of feedback information
`selected from a group consisting of: information for use in
`performing beam-forming; antenna selection/gro uping infor-
`mation.
`
`In some embodiments, a transmission format to
`[0006]
`each receiver is selected from a group oftransmission formats
`consisting of: spatial multiplexing; vector weighted spatial
`multiplexing; matrix weighted
`spatial multiplexing;
`
`K-stream spatial multiplexing employing more than K trans-
`mit antennas; single stream STTD; single stream STTD with
`proportional weightng and antenna selection; multi-stream
`STTD; multi-stream STUD with layer weighting; multi-
`stream STTD with a combination of layer weighting and
`proportional weighting; and hybrid beam—forming and spatial
`multiplexing.
`
`In some embodiments, a defined sub-set ofavailable
`[0007]
`formats is made available for a given receiver, and wherein
`the given receiver feeds back a selection of one ofthe defined
`sub-set of available formats.
`
`In some embodiments, each receiver performs
`[0008]
`respective channel measurements and feeds back information
`for use in performing beam—forrning based on the respective
`channel measurements.
`
`In some embodiments, the information for use in
`[0009]
`performingbeam-forming is selected from a group consisting
`of: a) elements of a measured channel matrix; b) elements of
`a V matrix of a SVD decomposed channel matrix; c) param-
`eters of a Givens decomposition of a V matrix of a SVD
`decomposed channel matrix; d) parameters of a truncated
`Givens decomposition of a V matrix of a SVD decomposed
`channel matrix, where one or more eigen—vectors are dis—
`carded; e) differentially encoded elements of a measured
`channel matrix; f) differentially encoded elements of a V
`matrix of a SVD decomposed channel matrix; g) differen-
`tially encoded parameters of a Givens decomposition or trun—
`cated Givens decomposition of aV matrix of a SVD decom-
`posed channel matrix; 11) Householder decomposition; i) full
`scalar quantization of any of the information types of a)
`through h); j) partial scalar quantization of any of the infor-
`mation types a) through g); k) scalar quantization of any one
`of the information types a) through h) where varying resolu-
`tion is used to quantize parameters; 1) vector quantization of
`any ofthe information types ofa) through h); m) a combina-
`tion of scalar quantization and differential quantization for
`any of the information types a) through 11); n) using a Delta
`Sigma quantizer for any of the information types a) through
`11); 0) binary beam-forming weights; p) a differential index
`into a set of vector quantizations; and q) pre-defined code-
`book.
`
`In some embodiments beam-forming feedback is
`[0010]
`performed by each receiver as a f1u1ction of receiver specific
`criteria.
`
`In some embodiments, the receiver specific criteria
`[0011]
`is selected from a group consisting of: Max SNR; b) Max
`Shannon capacity; and c) True receiver operational process.
`
`In some embodiments, antenna selection/grouping
`[0012]
`information is at least one information type selected from a
`group consisting of: a) selection between SM (spatial multi—
`plexing) and STTD (space time transmit diversity) transmis-
`sion format; b) selection of particular antennas for SM trans-
`mission; 0) selection and grouping of particular antennas for
`STTD transmission; and d) eigen—mode selection inforrna—
`tion.
`
`In some embodiments, the system further comprises
`[0013]
`the receiver determining the antenna selection/grouping
`information by performing a step selected from a group of
`steps consisting of: performing SVD decomposition and dis—
`carding weak eigen-modes; selecting antennas using deter-
`minants of sub-MIMO channel matrices.
`
`44
`
`44
`
`

`

`US 2008/0108310 A1
`
`May 8, 2008
`
`In some embodiments, feed back andbcam-forming
`[0014]
`and/or antenna selection/grouping is performed for sub—car—
`riers of a multi-carrier system to a resolution selected from a
`group consisting of: a) for every sub-carrier individually; b)
`for groups of consecutive sub-carriers; c) for an entire set of
`sub—carriers; d) for sets of groups of sub—carriers.
`
`n some embodiments, transmission matrices and
`:0015]
`feedback are in accordance with one of FIGS. 11 to 14.
`
`the transmitter transmits
`11 some embodiments,
`:0016]
`pilots on each transmit antenna for use in performing channel
`estimation.
`
`n some embodiments, at least some ofthe pilots are
`:0017]
`puncturec pilots.
`
`n some embodiments, at least some of the pilots
`:0018]
`comprise un-coded pilots for use by multiple receivers.
`
`n some embodiments, the pilots comprise user spe-
`:0019]
`cific pre—coded pilots for use by particular receivers receivers.
`
`n some embodiments, the pilots comprise user spe—
`:0020]
`cific pre-coded pilots for use by particular receivers receivers
`and un-coded pilots for use by multiple receivers.
`
`the pilot patterns are as
`n some embodiments,
`:0021]
`shown in any one of FIGS. 17—23 with generalizations as
`described.
`
`the pilot patterns are as
`n some embodiments,
`:0022]
`shown in one of FIGS. 26-31 with generalizations as
`described.
`
`
`
`
`
`
`
`FIG. 2 is a block diagram representation ofa base
`[0032:
`station according to one embodiment ofthe present invention;
`
`FIG. 3 is a block diagram representation of a mobile
`[0033:
`terminal according to one embodiment of the present inven-
`tion';
`
`FIG. 4 is a logical breakdown of an OFDM trans-
`[0034:
`mitter architecture according to one embodiment of the
`present invention;
`
`FIG. 5 is a logical breakdown ofan OFDM receiver
`[0035:
`architecture according to one embodiment of the present
`invention;
`
`FIG. 6 is a first example schematic diagram for
`[0036:
`beam-forming spatial multiplexing (SM) transmission using
`matrix or vector weighting according to an embodiment ofthe
`invention;
`
`FIG. 7 is a second example schematic diagram for
`[0037:
`beam—forming SM transmission with matrix weighting
`accorc ing to an embodiment of the invention:
`
`FIG. 8 is a schematic diagram for use in describing
`[0038:
`antenna/sub-channel selection criteria;
`
`FIG. 9 is a graphical comparison of fixed D-STTD
`[0039:
`(double—space—time time division) and antenna grouping
`D-ST'ID:
`
`FIG. 10 is a schematic diagram of sub-channel allo-
`[0040:
`cation for a 4-antenna transmitter and two 2-antenna receivers
`accorcing to an embodiment of the invention;
`
`FIG. 11 is a closed loop STC/VIIMO 3—transmit
`[0041:
`antenna grouping arrangement
`in accordance with an
`embodiment of the invention;
`
`FIG. 12 is a closed loop STC/VIIMO 3-transmit
`[0042:
`antenna selection arrangement
`in accordance with an
`embodiment of the invention;
`
`FIG. 13 is a closed loop STC/VIIMO 4—transmit
`[0043:
`antenna arrangement in accordance with an embodiment of
`the invention;
`
`FIG. 14 is a closed loop STC/VIIMO 4-transmit
`[0044:
`antenna arrangement in accordance with an embodiment of
`the invention;
`
`FIGS. 15 and 16 show binary uni ary beam—forming
`[0045:
`matrices in accordance with embodiments of the invention;
`
`
`
`
`
`n some embodiments, feedback information is
`:0023]
`transmitted using a feedback chalmel having the structure of
`one of FIGS. 46 to 48 with generalizations as described.
`
`11 some embodiments, at least one receiver has a
`:0024]
`plurality of receive antennas.
`
`n some embodiments, the at least one receiver com-
`:0025]
`prises a plurality of receivers.
`
`n some embodiments, sub-channels are defined
`:0026]
`using at least one of; AMC sub-channels, where respective
`adaptive modulation and coding is defined for each AMC
`sub-channel; PUSC sub-channels.
`
`In another embodiment, a receiver is provided that is
`[0027]
`adapted to implement receiver functionality as summarized
`above.
`
`In another embodiment, a transmitter is provided
`[0028]
`that is adapted to implement transmitter functionality as sum-
`marized above.
`
`[0029] Other aspects and features of the present invention
`will become apparent to those ordinarily skilled in the art
`upon review of the following description of specific embodi-
`ments ofthe invention in conjunction with the accompanying
`figures.
`
`
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0030] Preferred embodiments ofthe invention will now be
`described with reference to the attached drawings in which:
`
`FIG. 17 is pilot mapping for a pilot allocation for
`[0046:
`4-antenna BS (base station) for the optional FUSC (full uti-
`lization sub-channel) and Optional AMC (adaptive modula-
`tion and coding) zones in 802.16d in accordance with an
`embodiment of the invention;
`
`FIGS. 18 and 19 are pilot mappings for a pilot allo—
`[0047]
`cation for four transmit antennas in which there is no punc-
`turing required in accordance with an embodiment of the
`invention;
`
`FIGS. 20 and 21 are pilot mappings for a pilot allo-
`[0048]
`cation for eight transmit antennas in accordance with an
`embodiments of the invention;
`
`[0031] FIG. 1 is a schematic diagram representation of a
`cellular connnunication system according to one embodi-
`ment of the present invention;
`
`FIGS. 22 and 23 are pilot mappings for a pilot allo—
`[0049]
`cation for twelve transmit antennas in accordance-with an
`embodiments of the invention;
`
`45
`
`45
`
`

`

`US 2008/0108310 A1
`
`May 8, 2008
`
`
`
`:0050] FIG. 24 is a schematic diagram showing an example
`ofpre—coding ofMIMO pilots in accordance with an embodi—
`ment of the invention;
`
`:0051] FIG. 25 is a schematic diagram showing an example
`ofpre—coding ofMIMO pilots in accordance with an embodi—
`ment of the invention suitable for larger antenna arrays;
`
`:0052] FIG. 26 is a pilot mapping showing a pre-codcd pilot
`design for a 2—antenna basestation (BS) for optional AMC in
`accordance with an embodiment of the invention;
`
`:0053] FIG. 27 is a second pre-eoded pilot design for a
`2—antenna basestation (BS) for optional AMC in accordance
`with an embodiment of the invention;
`
`:0054] FIG. 28 is a pilot mapping showing apre-eoded pilot
`design for a 3—antenna basestation (BS) for optional AMC in
`accordance with an embodiment of the invention;
`
`:0055] FIG. 29 is a pilot mapping showing a pilot design for
`a 4—antenna basestation (BS) for optional AMC in accordance
`with an embodiment of the invention;
`
`:0056] FIG. 30 is a pilot mapping showing a pre-coded pilot
`design for a 2-ante1ma BS for PUSC (partial utilization sub-
`chamiel) zone in accordance with an embodiment of the
`invention;
`
`[0057] FIG. 31 is a pi ot mapping showing apre-codcd pilot
`
`design for a 4—antenna 3S for PUSC zone in accordance with
`an embodiment of the invention;
`
`[0058] FIG. 32 is a schematic diagram of a set of closed
`loop STC/MIMO arrangements with beam—fonner structures
`in accordance with an embodiment of the invention;
`
`[0059] FIGS. 33, 34, 35 and 36 present a comparison of
`SVD (singular value decomposition) to antenna grouping;
`[0060] FIG. 37 is a block diagram ofa system employing a
`direct differential encoding in accordance with an embodi-
`ment of the invention in which MIMO channel and CQI
`(channel quality indication) are separately fed back;
`
`
`
`
`[0061] FIG. 38 is a block diagram ofa system employing a
`direct differential encoding in accordance with another
`embodiment of the invention in which MIMO chamiel and
`CQI are 'ointly fed back;
`
`:0062] FIG. 39 is a block diagram of a system employing a
`direct di erential encoding in accordance with an embodi—
`ment of the invention featuring 1 bit DPCM;
`
`:0063] FIG. 40 is a block diagram of a system employing a
`direct di erential encoding in accordance with an embodi—
`ment of the invention and using a 1 bit AZ modulator;
`
`:0064] FIG. 41 is a block diagram ofa system employing a
`direct di erential encoding in accordance with an embodi—
`ment of the invention for multiple users;
`
`:0065] FIG. 42 contains a table ofvarious direct differential
`encoding feedback in accordance with embodiments of the
`invention;
`
`:0066] FIG. 43 is a block diagram ofa system employing an
`SVD based Givens transfonn feedback in accordance with an
`embodiment of the invention;
`
`:0067] FIG. 44 is another example of an SVD based Givens
`transfomi in accordance with an embodiment ofthe invention
`in which a further spherical code based quantization is per-
`formed;
`
`
`
`FIG. 45 is a block diagram of a system employing a
`[0068:
`receiver based Givens transform in accordance with an
`embodiment of the invention;
`
`FIG. 46 is an example of space-time coding for use
`[0069'
`on a GQICH (channel quality indication channel) in accor-
`dance with an embodiment of the invention suitable for a
`s1n r e input single output ap