111111
`
`1111111111111111111111111111111111111111111111111111111111111111111111111111
`US 20030035491Al
`
`(19) United States
`(12) Patent Application Publication
`Walton et al.
`
`(10) Pub. No.: US 2003/0035491 Al
`Feb. 20, 2003
`(43) Pub. Date:
`
`(54) METHOD AND APPARATUS FOR
`PROCESSING DATA IN A MULTIPLE-INPUT
`MULTIPLE-OUTPUT (MIMO)
`COMMUNICATION SYSTEM UTILIZING
`CHANNEL STATE INFORMATION
`
`(76)
`
`Inventors: Jay R. Walton, Westford, MA (US);
`Mark Wallace, Bedford, MA (US);
`John W. Ketchum, Harvard, MA (US);
`Steven J. Howard, Ashland, MA (US)
`
`Correspondence Address:
`QUALCOMM Incorporated
`Attn: Patent Department
`5775 Morehouse Drive
`San Diego, CA 92121-1714 (US)
`
`(21) Appl. No.:
`
`09/854,235
`
`(22) Filed:
`
`May 11,2001
`
`Publication Classification
`
`(51)
`
`Int. CI? .............................. H04L 1/02; H04B 7/02;
`H04K 1!10; H04L 27 /28;
`H04B 1/00
`
`(52) U.S. Cl. ........................... 375/267; 375/260; 455/132
`
`(57)
`
`ABSTRACT
`
`Techniques to "successively" process received signals at a
`receiver unit in a MIMO system to recover transmitted data,
`and to "adaptively" process data at a transmitter unit based
`on channel state information available for the MIMO chan(cid:173)
`nel. A successive cancellation receiver processing technique
`is used to process the received signals and performs a
`number of iterations to provide decoded data streams. For
`each iteration, input (e.g., received) signals for the iteration
`are processed to provide one or more symbol streams. One
`of the symbol streams is selected and processed to provide
`a decoded data stream. The interference due to the decoded
`data stream is approximately removed (i.e., canceled) from
`the input signals provided to the next iteration. The channel
`characteristics are estimated and reported back to the trans(cid:173)
`mitter system and used to adjust (i.e., adapt) the processing
`(e.g., coding, modulation, and so on) of data prior to
`transmission.
`
`110
`..........
`
`150
`,.--.-
`
`124a
`
`152a
`
`SONY EX. 1007
`Page 1
`
`

`

`'"""'
`'"""' >
`
`8 Ul
`c
`@
`N c
`'JJ.
`Cj
`
`'0
`~
`
`'"""' c
`'"""' 0 ......,
`~ .....
`'JJ. =(cid:173)~
`8
`N c
`~=
`N
`"?'
`~
`"'!"j
`
`.... 0 =
`0' -....
`~
`.... 0 =
`~ 't:l -....
`~ = .....
`~ .....
`""C
`
`~ .....
`
`I")
`
`~ .....
`
`I")
`
`I CSI
`
`I I
`
`RX MIMO/Data H Data
`
`160
`
`156
`
`Sink
`
`Processor
`
`•
`• •
`
`154a
`
`FIG. 1
`
`Processor
`
`132
`
`I
`
`CSI
`
`Processor
`
`Processor
`
`Source
`
`Data H TX Data H TX MIMO
`
`120
`
`114
`
`112
`
`150
`
`..-
`
`152a
`
`124a
`
`100
`
`~
`110
`
`SONY EX. 1007
`Page 2
`
`

`

`'"""'
`'"""' >
`
`8 Ul
`c
`@
`N c
`'JJ.
`Cj
`
`'0
`~
`
`'"""' c
`0 ......,
`N
`~ .....
`'JJ. =(cid:173)~
`8
`N c
`~
`N
`"?'
`~
`"'!"j
`
`~ ..... .... 0 =
`0' -....
`~
`~ ..... .... 0 =
`~ 't:l -....
`~ = .....
`~ .....
`""C
`
`I")
`
`I")
`
`CSI
`I
`t
`
`r--
`
`VNt ... MOD
`
`r
`
`...
`
`SNc
`
`1t
`
`,I
`122t
`
`• • •
`
`DEMUX
`MUX/
`
`"'
`
`-
`
`v1 .. MOD
`,I
`122a
`
`r
`
`2)2
`
`120a
`
`s1
`
`\
`
`L----------------------1
`r;+ Encoder ~
`
`FIG. 2
`
`CSI (Nc)
`
`+
`
`~
`
`+
`
`__.
`
`lnterleaver
`Channel
`
`I
`I
`
`ONe
`
`I
`I
`I
`
`I
`I
`I
`I
`
`Mapping
`Symbol
`·"'·
`216
`
`r--------------~--------,
`
`2)6
`
`,J
`214
`
`,J
`212
`
`I
`I
`I
`
`210a
`
`L-----------t-----------1
`~
`
`210n
`
`CSI (1)
`
`+
`
`• •
`•
`
`+
`
`r-+
`
`lnterleaver
`Channel
`
`Encoder -+
`
`I
`I
`I
`
`I
`I
`I
`
`I
`I
`I
`I
`
`+
`
`Mapping
`Symbol
`
`r--------------~--------1
`
`,J
`214
`
`,I
`212
`
`I
`I
`
`DEMUX
`
`+
`
`Bits
`
`Information
`
`+
`
`Pilot Data
`
`"'
`208
`
`Symbol Streams
`
`Modulation
`
`~
`
`114a
`
`Streams
`
`\
`
`Data
`
`~
`
`110a
`
`SONY EX. 1007
`Page 3
`
`

`

`'"""'
`'"""' >
`
`8 Ul
`c
`@
`N c
`'JJ.
`Cj
`
`'0
`~
`
`'"""' c
`0 .....,
`~
`~ ....
`'JJ. =(cid:173)~
`8
`N c
`~=
`N
`?'
`~
`"!"j
`
`~ .... .... 0 =
`~ 0' -....
`~ .... .... 0 =
`'t:l -....
`> 't:l
`~ .... ~ = ....
`
`I")
`
`I")
`
`"'C
`
`1 ~
`
`"
`124a
`
`I
`I
`
`I
`I
`I
`I
`
`I
`I
`
`I
`I
`I
`I
`
`:
`--------------~-------1
`
`converter
`
`Generator
`
`IFFT _. Prefix _.
`
`Cyclic
`
`,I
`322f
`
`~
`320f
`
`I ------
`
`I
`I
`VNI
`
`I
`
`Up-
`
`,I
`324f
`
`122t
`
`•
`• •
`
`~---------------------1
`_ .. IFFT ~ Prefix _.
`
`converter
`
`Up-
`
`Generator
`
`Cyclic
`
`I
`1 ..
`
`v1
`
`3348
`
`122a
`
`,I
`320a
`------
`
`I
`I
`I
`
`Vector Streams
`
`Symbol
`
`\
`
`Combiner
`
`t-~
`
`• r-!-+
`
`~
`324t
`
`• •
`•
`
`Combiner
`
`• • • r-r+
`
`~
`324a
`
`120c
`
`Subchannel
`
`~
`322a
`
`S1,Nc
`1,1_ .. MIMO
`s
`
`I
`
`,I
`322n
`•
`•
`•
`ck1
`
`Processor
`
`FIG. 3
`
`SNL1 Subchannel
`
`CSI
`
`Processor
`
`..
`
`MIMO
`
`I L
`SNL,Nc
`
`Data Processor
`
`~ Subchannel
`DNL
`Frequency
`
`CSI
`....
`
`Symbol Streams
`
`Modulation
`
`\
`
`Data Processor
`r--+ Subchannel
`D1
`Frequency
`
`~
`310a
`
`~
`310!
`
`•
`•
`•
`
`CSI
`t
`
`DEMUX
`
`~
`
`Bits
`Inform a
`
`::2_8
`
`114c
`
`\
`
`Data Streams
`Subchannel
`Frequency
`
`~
`
`110c
`
`SONY EX. 1007
`Page 4
`
`

`

`Patent Application Publication Feb. 20, 2003 Sheet 4 of 10
`
`US 2003/0035491 A1
`
`Start
`
`Perform linear or non-linear
`equalization on the NR
`received signals
`
`Determine SNR for
`transmitted signals
`included in received signals
`
`412
`
`414
`
`Recover (demodulate and
`decode) a selected transmitted
`(e.g., one with best SNR)
`
`416
`
`NO
`
`420
`
`422
`
`Form estimate of interference
`presented by recovered
`transmitted signal on each
`of the received signals
`
`Cancel interference due
`to recovered transmitted
`signal from each received
`signal to derive input
`signal for the next iteration
`
`End
`
`FIG. 4
`
`SONY EX. 1007
`Page 5
`
`

`

`Patent Application Publication Feb. 20, 2003 Sheet 5 of 10
`
`US 2003/0035491 A1
`
`150a
`Jtr-'
`
`156
`~
`______________ JJ~~
`r520a
`Channel MIMO/
`data processor
`
`152a
`
`1;4a
`
`DE MOD
`
`[
`
`152r
`
`•
`• •
`1~4r
`
`DE MOD I--
`
`I
`1
`1 !: 1
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`
`4
`
`f 2
`
`I
`1
`t---.1.--J--.... ~cs 1 ( 1 )
`• I
`1----.--1--J.--..•Decoded Data Stream (1)
`I
`I
`I
`I
`I
`I
`~
`I
`I
`I
`
`Controller
`
`r530a
`Interference
`Canceller
`r2
`L------ ~-----------1
`-- ___________ JJ~Q
`r520b
`:
`; + CSI (2)
`__. Channel MIMO/
`data processor
`--..Decoded Data Stream (2)
`
`1
`I
`I
`1
`I
`
`11
`
`
`
`!.__
`I ....
`
`4
`
`1r
`
`r530b
`Interference
`Canceller
`I
`r3
`1
`L------ ~----------_I
`+---
`• • •
`r--------------L--,
`510n
`r520n
`I
`I n
`I r 4 Channel MIMO/
`data processor
`
`--,. CSI (Nc)
`,... ecoded Data Stream (Nc)
`o
`
`1
`I
`I
`1
`
`i
`1
`L - - - - - - - - - - - --- - - -'
`
`11
`
`
`
`FIG. 5
`
`SONY EX. 1007
`Page 6
`
`

`

`Patent Application Publication Feb. 20, 2003 Sheet 6 of 10
`
`US 2003/0035491 A1
`
`610x
`~-----------------r-----------1
`614
`616
`618
`J
`,J
`~
`Match
`Filter
`
`1
`I
`r I
`
`,..
`
`Multiplier
`
`!'
`
`-,.
`
`Combiner
`
`, 626
`~R1
`r624
`Matrix
`CSI
`Processor ~ Processor
`
`J
`
`~HH
`r622
`Channel
`Estimator
`t
`------------------------------1
`FIG. 6A
`
`I
`I
`!"
`I
`I
`I
`I
`I
`I
`I
`
`I
`I
`I
`I
`
`520x
`}IC""'
`
`620
`L
`RX Data
`Processor
`
`~
`
`Decoded
`--+ Data
`Stream
`
`CSI
`
`610y
`.------------------~----------1
`634
`636
`638
`I
`I
`!"
`RX D
`Combiner ~-+1
`ata
`Processor
`
`1
`I
`r I
`....;;:_-r+l Multiplier
`
`"
`!
`
`Multiplier
`
`....,
`!
`
`M
`
`D -1
`-V
`
`Adaptive
`Processor
`
`CSI
`Processor
`
`------------------------------1
`FIG. 68
`
`1
`I
`I
`I
`
`620
`
`520y
`}IC""'
`
`Decoded
`Data
`Stream
`
`CSI
`
`SONY EX. 1007
`Page 7
`
`

`

`Patent Application Publication Feb. 20, 2003 Sheet 7 of 10
`
`US 2003/0035491 A1
`
`520z
`~
`
`CSI
`
`~ 6]0
`Decoded
`RX Data
`Data
`Processor -~
`Stream
`
`610z
`~------------~--------------1
`626
`I
`I
`I
`I
`,J
`I
`I
`CSI
`I
`I
`I
`I
`Processor
`I
`I
`I
`I
`r I
`I
`
`.
`
`6)4
`Forward
`Receive
`
`656
`
`++
`Processor 1 ~8
`
`1--,.
`I
`I
`I
`I
`I
`I
`I
`I
`
`Feedback
`Processor
`
`2JOx
`Channel
`Data
`Processor
`
`1-r
`I
`I
`I
`I
`... I
`I
`I
`I
`
`----------------------------
`FIG. 6C
`
`Input
`Symbol
`Vector
`
`710
`
`Selector
`
`Control
`Signal
`
`712
`
`De mod
`Element
`
`714
`
`716
`
`De-
`lnterleaver
`
`Decoder
`
`620
`~
`
`Decoded
`Data
`Stream
`
`FIG. 7
`
`530x
`~
`
`Decoded
`Data
`Stream
`
`812
`
`810
`
`210y
`
`Channel
`Simulator
`
`Channel Data
`Processor
`
`FIG. 8
`
`SONY EX. 1007
`Page 8
`
`

`

`Patent Application Publication Feb. 20, 2003 Sheet 8 of 10
`
`US 2003/0035491 A1
`
`"'0
`c
`..=;:::
`0 "'0 t
`,_
`u
`:J
`CD
`..=;::: ..E
`(j)
`
`+-'
`
`I
`I
`I
`L .&. ... L -
`
`I
`I
`I
`
`I
`I
`I
`I
`I
`I l l I
`I l l I
`I l l I
`I l l I
`
`I
`I
`I
`I
`
`I
`I
`I
`
`I
`
`I
`
`I
`I
`
`-,--j---
`
`I
`
`I
`
`I
`I
`, , - i
`I
`
`I I I I I
`II II I
`I
`I I I I I
`II I I I
`I
`I I I I I I
`I
`I
`II II I
`I
`II I I I
`I
`I
`I
`II II I
`I
`I
`II I I
`I
`I
`I
`II II I
`I
`I
`I
`II I I I
`I
`I
`I
`I
`II I I I
`I
`I
`I
`..J ............ U .l. L L L ..J ... .L ...... 1 ............ Ll..l J. .L. .J -I- ..1 ...... L ......
`II II
`Jill
`II II
`I l l
`II I I
`I l l
`II II
`I l l
`II II
`II I
`II II
`I l l
`II II
`I l l
`II II
`I l l
`II II
`I
`I l l
`II II
`I
`I l l
`--.----IIi
`I
`II
`I
`II II
`I l l
`I
`II
`I
`I
`II II
`I l l
`II
`I
`I
`II II
`I l l
`I
`II
`I
`II II
`I l l
`II
`I
`I
`II II
`I l l
`I I
`I
`I
`II II I
`I l l
`I I
`I
`I
`II I I I
`I l l
`I I
`I
`I
`II II I
`I
`I l l
`II I
`I
`I
`II II I
`I
`I l l
`... ., ... "'" ... -n T r"f"" r" ., ... T ...... , ......... • 1"'1"1 T T "1 ... , ... ., ...... r ... •
`... , ... - T ......... .,T~J-1-r' T ... i
`I
`I l l I
`I
`I
`I I I I I I
`I
`I
`1111
`I
`I
`I
`I l l I
`I
`I I I I I I
`I
`1111
`I
`I
`I
`I I I I
`I
`I l l I I
`II II I
`I
`I I I I
`I
`I
`I I I I I
`II II I
`I
`I
`I II I
`I
`I I I I I I
`1111 I
`I
`I
`I
`1111 I
`I l l !
`I I I I I
`II II I
`I
`I I I I I
`II II
`I
`II I I I
`I I I I I I
`I
`II I I I
`II I I I
`I
`I
`I
`I
`II I l l I
`I
`I
`I
`II I I I
`...... ...IJ.LJ ... I ... L .l ... L ... ..1 ............ u .&. LL L ..J ... .1. ...... 1 ............ 1..1..1 .L .1.
`I I I I I I
`I
`II
`I I I I I
`II
`II
`II
`II
`II
`
`.-.- -.- i- --,----.j i.-
`
`I
`
`-.-
`
`-,--.--
`
`I
`I
`
`I
`
`I
`
`I
`
`I
`
`I
`I
`I
`I
`I
`I
`..1 ... 1 ... ..1 ...... L ......
`
`~ 111111
`I~III'E --~111111 I
`:+:-:~:.&i- ~- -:-~:~~f~~~- +- -:---- .1 f
`
`I
`
`IIIII..,....,_
`I
`II
`1-,.._J--..
`Ill
`'n l I "o/-- ... L.Lt
`\.fj/.., I
`I
`I
`I
`I
`II II
`-l,r:..
`I"' --L
`I
`II I I I
`I
`I
`I l l I
`0.._
`1111111
`I
`IIIII
`I
`11111111~1111
`I
`I
`0111111 I
`I
`I
`I I I I I
`I
`I
`I
`I
`l"fL,.H_I
`I
`I
`I
`IIIII
`I
`I
`I
`I
`111~11 I
`I
`1111
`I
`I
`I
`I
`11111~1 I
`11~11 I
`- , ---- n T I'* I'*" f'\Y T - -~--- -
`r"'l..
`-~- ., -
`•
`r"' - -
`I
`I I I I I I 1'-¢
`I I I I I ~I
`I
`I I I I I
`I
`"L
`I
`I I I I I I
`I
`I
`I I I I I
`I
`.......
`I I I I I I
`11111111 I~ 1111111
`"-~1111111
`IIIII I
`I
`I
`I
`I I I
`I
`I
`II I
`I
`I
`I
`I
`I
`.... L..I
`
`I
`
`I
`I
`
`SONY EX. 1007
`Page 9
`
`

`

`Patent Application Publication Feb. 20, 2003 Sheet 9 of 10
`
`US 2003/0035491 A1
`
`---------------------~----------~-------
`
`I
`
`1
`
`--------- -•----------- ---------- ..... _--------- -L..--
`
`I
`
`---------------------L----------....I-----------
`
`1
`I
`
`I
`I
`
`I
`
`SONY EX. 1007
`Page 10
`
`

`

`Patent Application Publication Feb. 20, 2003 Sheet 10 of 10
`
`US 2003/0035491 A1
`
`I
`I
`l""t(cid:173)
`ICV)
`10)
`
`----------·--------
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`- -1- -
`I
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`I
`- ~ -
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`---t-----------t-
`
`1
`
`I
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`-
`
`I
`
`- -·- -
`I
`
`-
`
`-
`
`-
`
`... -
`
`-
`
`-
`
`-
`
`I
`- ~ -
`
`I
`I
`
`-
`
`-
`
`-
`
`-
`
`... -
`
`-
`
`-
`
`- -t- -
`
`-
`
`-
`
`-
`
`-
`
`-
`
`I
`............................. I ............................... L ... ... ... ... ... ... ... ... ... ...
`I
`
`... ............................ L. ... ...
`I
`
`----------•----------- ----------~-----------
`
`I
`
`I
`
`SONY EX. 1007
`Page 11
`
`

`

`US 2003/0035491 A1
`
`Feb.20,2003
`
`1
`
`METHOD AND APPARATUS FOR PROCESSING
`DATA IN A MULTIPLE-INPUT
`MULTIPLE-OUTPUT (MIMO) COMMUNICATION
`SYSTEM UTILIZING CHANNEL STATE
`INFORMATION
`
`BACKGROUND
`
`[0001] 1. Field
`
`[0002] The present invention relates generally to data
`communication, and more specifically to a novel and
`improved method and apparatus for processing data in a
`multiple-input multiple-output (MIMO) communication
`system utilizing channel state
`information to provide
`improved system performance.
`
`[0003] 2. Background
`
`[0004] Wireless communication systems are widely
`deployed to provide various types of communication such as
`voice, data, and so on. These systems may be based on code
`division multiple access (CDMA), time division multiple
`access (TDMA), orthogonal frequency division multiplex
`(OFDM), or some other multiplexing techniques. OFDM
`systems may provide high performance for some channel
`environments.
`
`[0005]
`In a terrestrial communication system (e.g., a cel(cid:173)
`lular system, a broadcast system, a multi-channel multi(cid:173)
`point distribution system (MMDS), and others), an RF
`modulated signal from a transmitter unit may reach a
`receiver unit via a number of transmission paths. The
`characteristics of the transmission paths typically vary over
`time due to a number of factors such as fading and multipath.
`
`[0006] To provide diversity against deleterious path effects
`and improve performance, multiple transmit and receive
`antennas may be used for data transmission. If the trans(cid:173)
`mission paths between the transmit and receive antennas are
`linearly independent (i.e., a transmission on one path is not
`formed as a linear combination of the transmissions on other
`paths), which is generally true to at least an extent, then the
`likelihood of correctly receiving a data
`transmission
`increases as the number of antennas increases. Generally,
`diversity increases and performance improves as the number
`of transmit and receive antennas increases.
`
`[0007] A multiple-input multiple-output (MIMO) commu(cid:173)
`nication system employs multiple (NT) transmit antennas
`and multiple (N~ receive antennas for data transmission. A
`MIMO channel formed by the NT transmit and NR receive
`antennas may be decomposed into Nc independent channels,
`with Nc~min{Ny, NR}. Each of the Nc independent chan(cid:173)
`nels is also referred to as a spatial subchannel of the MIMO
`channel and corresponds to a dimension. The MIMO system
`can provide improved performance (e.g., increased trans(cid:173)
`mission capacity) if the additional dimensionalities created
`by the multiple transmit and receive antennas are utilized.
`
`SUMMARY
`
`[0009] Aspects of the invention provide techniques to
`process the received signals at a receiver unit in a multiple(cid:173)
`input multiple-output (MIMO) system to recover the trans(cid:173)
`mitted data, and to adjust the data processing at a transmitter
`unit based on estimated characteristics of a MIMO channel
`used for data transmission. In an aspect, a "successive
`cancellation" receiver processing
`technique (described
`below) is used to process the received signals. In another
`aspect,
`the channel characteristics are estimated and
`reported back to the transmitter system and used to adjust
`(i.e., adapt) the processing (e.g., coding, modulation, and so
`on) of data prior to transmission. Using a combination of the
`successive cancellation receiver processing technique and
`adaptive transmitter processing technique, high performance
`may be achieved for the MIMO system.
`
`[0010] A specific embodiment of the invention provides a
`method for sending data from a transmitter unit to a receiver
`unit in a MIMO communication system. In accordance with
`the method, at the receiver unit, a number of signals are
`initially received via a number of receive antennas, with
`each received signal comprising a combination of one or
`more signals transmitted from the transmitter unit. The
`received signals are processed in accordance with a succes(cid:173)
`sive cancellation receiver processing technique to provide a
`number of decoded data streams, which are estimates of the
`data streams transmitted from the transmitter unit. Channel
`state information ( CSI) indicative of characteristics of a
`MIMO channel used to transmit the data steams are also
`determined and transmitted back to the transmitter unit. At
`the transmitter unit, each data stream is adaptively processed
`prior to transmission over the MIMO channel in accordance
`with the received CSI.
`
`[0011] The successive cancellation receiver processing
`scheme typically performs a number of iterations to provide
`the decoded data streams, one iteration for each decoded
`data stream. For each iteration, a number of input signals for
`the iteration are processed in accordance with a particular
`linear or non-linear processing scheme to provide one or
`more symbol streams. One of the symbol streams is then
`selected and processed to provide a decoded data stream. A
`number of modified signals are also derived based on the
`input signals, with the modified signals having components
`due to the decoded data stream approximately removed (i.e.,
`canceled). The input signals for a first iteration are the
`received signals and the input signals for each subsequent
`iteration are the modified signals from a preceding iteration.
`
`[0012] Various linear and non-linear processing schemes
`may be used to process the input signals. For a non(cid:173)
`dispersive channel (i.e., with fiat fading), a channel corre(cid:173)
`lation matrix inversion (CCMI) technique, a minimum mean
`square error (MMSE) technique, or some other techniques
`may be used. And for a time-dispersive channel (i.e., with
`frequency selective fading), an MMSE linear equalizer
`(MMSE-LE), a decision feedback equalizer (DFE), a maxi(cid:173)
`mum-likelihood sequence estimator (MLSE), or some other
`techniques may be used.
`
`[ 0008] There is therefore a need in the art for techniques
`to process a data transmission at both the transmitter and
`receiver units to take advantage of the additional dimen(cid:173)
`sionalities created by a MIMO system to provide improved
`system performance.
`
`[0013] The available CSI may include, for example, the
`signal-to-noise-plus-interference (SNR) of each transmis(cid:173)
`sion channel to be used for data transmission. At the
`transmitter unit, the data for each transmission channel may
`be coded based on the CSI associated with that channel, and
`
`SONY EX. 1007
`Page 12
`
`

`

`US 2003/0035491 Al
`
`Feb.20,2003
`
`2
`
`the coded data for each transmission channel may further be
`modulated in accordance with a modulation scheme selected
`based on the CSI.
`[0014] The invention further provides methods, systems,
`and apparatus that implement various aspects, embodiments,
`and features of the invention, as described in further detail
`below.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0015] The features, nature, and advantages of the present
`invention will become more apparent from the detailed
`description set forth below when taken in conjunction with
`the drawings in which like reference characters identify
`correspondingly throughout and wherein:
`[0016] FIG. 1 is a diagram of a multiple-input multiple(cid:173)
`output (MIMO) communication system capable of imple(cid:173)
`menting various aspects and embodiments of the invention;
`[0017] FIG. 2 is a block diagram of an embodiment of a
`MIMO transmitter system capable of processing data for
`transmission based on the available CSI;
`[0018] FIG. 3 is a block diagram of an embodiment of a
`MIMO transmitter system which utilizes orthogonal fre(cid:173)
`quency division modulation (OFDM);
`[0019] FIG. 4 is a flow diagram illustrating a successive
`cancellation receiver processing technique to process NR
`received signals to recover NT transmitted signals;
`[0020] FIG. 5 is a block diagram of a receiver system
`capable of implementing various aspects and embodiments
`of the invention;
`[0021] FIGS. 6A, 6B, and 6C are block diagrams of three
`channel MIMO/data processors, which are capable of imple(cid:173)
`menting a CCMI technique, a MMSE technique, and a DFE
`technique, respectively;
`[0022] FIG. 7 is a block diagram of an embodiment of a
`receive (RX) data processor;
`[0023] FIG. 8 is a block diagram of an interference
`canceller; and
`[0024] FIGS. 9A, 9B, and 9C are plots that illustrate the
`performance for various receiver and transmitter processing
`schemes.
`
`DETAILED DESCRIPTION
`
`[0025] FIG. 1 is a diagram of a multiple-input multiple(cid:173)
`output (MIMO) communication system 100 capable of
`implementing various aspects and embodiments of the
`invention. System 100 includes a first system 110 in com(cid:173)
`munication with a second system 150. System 100 can be
`operated to employ a combination of antenna, frequency,
`and temporal diversity (described below) to increase spectral
`efficiency, improve performance, and enhance flexibility. In
`an aspect, system 150 can be operated to determine the
`characteristics of a MIMO channel and to report channel
`state information (CSI) indicative of the channel character(cid:173)
`istics that have been determined in this way back to system
`110, and system 110 can be operated to adjust the processing
`(e.g., encoding and modulation) of data prior to transmission
`based on the available CSI. In another aspect, system 150
`can be operated to process the data transmission from
`
`system 110 in a manner to provide high performance, as
`described in further detail below.
`
`[0026] At system 110, a data source 112 provides data
`(i.e., information bits) to a transmit (TX) data processor 114,
`which encodes the data in accordance with a particular
`encoding scheme, interleaves (i.e., reorders) the encoded
`data based on a particular interleaving scheme, and maps the
`interleaved bits into modulation symbols for one or more
`transmission channels used for transmitting the data. The
`encoding increases the reliability of the data transmission.
`The interleaving provides time diversity for the coded bits,
`permits the data to be transmitted based on an average
`signal-to-noise-plus-interference-ratio (SNR) for the trans(cid:173)
`mission channels used for the data transmission, combats
`fading, and further removes correlation between coded bits
`used to form each modulation symbol. The interleaving may
`further provide frequency diversity if the coded bits are
`transmitted over multiple frequency subchannels. In an
`aspect, the encoding, interleaving, and symbol mapping (or
`a combination thereof) are performed based on the CSI
`available to system 110, as indicated in FIG. 1.
`
`[0027] The encoding, interleaving, and symbol mapping at
`transmitter system 110 can be performed based on numerous
`schemes. One specific scheme is described in U.S. patent
`application Ser. No. 09/776,075, entitled "CODING
`SCHEME FOR A WIRELESS COMMUNICATION SYS(cid:173)
`TEM," filed Feb. 1, 2001, assigned to the assignee of the
`present application and incorporated herein by reference.
`Another scheme is described in further detail below.
`
`[0028] MIMO system 100 employs multiple antennas at
`both the transmit and receive ends of the communication
`link. These transmit and receive antennas may be used to
`provide various forms of spatial diversity (i.e., antenna
`diversity), including transmit diversity and receive diversity.
`Spatial diversity is characterized by the use of multiple
`transmit antennas and one or more receive antennas. Trans(cid:173)
`mit diversity is characterized by the transmission of data
`over multiple transmit antennas. Typically, additional pro(cid:173)
`cessing is performed on the data transmitted from the
`transmit antennas to achieved the desired diversity. For
`example, the data transmitted from different transmit anten(cid:173)
`nas may be delayed or reordered in time, coded and inter(cid:173)
`leaved across the available transmit antennas, and so on.
`Receive diversity is characterized by the reception of the
`transmitted signals on multiple receive antennas, and diver(cid:173)
`sity is achieved by simply receiving the signals via different
`signal paths.
`
`[0029] System 100 may be operated in a number of
`different communication modes, with each communication
`mode employing antenna, frequency, or temporal diversity,
`or a combination thereof. The communication modes may
`include, for example, a "diversity" communication mode
`and a "MIMO" communication mode. The diversity com(cid:173)
`munication mode employs diversity to improve the reliabil(cid:173)
`ity of the communication link. In a common application of
`the diversity communication mode, which is also referred to
`as a "pure" diversity communication mode, data is trans(cid:173)
`mitted from all available transmit antennas to a recipient
`receiver system. The pure diversity communications mode
`may be used in instances where the data rate requirements
`are low or when the SNR is low, or when both are true. The
`MIMO communication mode employs antenna diversity at
`
`SONY EX. 1007
`Page 13
`
`

`

`US 2003/0035491 Al
`
`Feb.20,2003
`
`3
`
`both ends of the communication link (i.e., multiple transmit
`antennas and multiple receive antennas) and is generally
`used to both improve the reliability and increase the capacity
`of the communication link. The MIMO communication
`mode may further employ frequency and/or temporal diver(cid:173)
`sity in combination with the antenna diversity.
`
`[0030] System 100 may utilize orthogonal frequency divi(cid:173)
`sion modulation (OFDM), which effectively partitions the
`operating frequency band into a number of (NJ frequency
`subchannels (i.e., frequency bins). At each time slot (i.e., a
`particular time interval that may be dependent on the band(cid:173)
`width of the frequency subchannel), a modulation symbol
`may be transmitted on each of the NL frequency subchan(cid:173)
`nels.
`
`[0031] System 100 may be operated to transmit data via a
`number of transmission channels. As noted above, a MIMO
`channel may be decomposed into Nc independent channels,
`with Nc~min{Ny, NR}. Each of the Nc independent chan(cid:173)
`nels is also referred to as a spatial subchannel of the MIMO
`channel. For a MIMO system not utilizing OFDM, there is
`typically only one frequency subchannel and each spatial
`subchannel may be referred to as a "transmission channel".
`For a MIMO system utilizing OFDM, each spatial subchan(cid:173)
`nel of each frequency subchannel may be referred to as a
`transmission channel.
`
`[0032] A MIMO system can provide improved perfor(cid:173)
`mance if the additional dimensionalities created by the
`multiple transmit and receive antennas are utilized. While
`this does not necessarily require knowledge of CSI at the
`transmitter, increased system efficiency and performance are
`possible when the transmitter is equipped with CSI, which
`is descriptive of the transmission characteristics from the
`transmit antennas to the receive antennas. The processing of
`data at the transmitter prior to transmission is dependent on
`whether or not CSI is available.
`
`[0033] The available CSI may comprise, for example, the
`signal-to-noise-plus-interference-ratio (SNR) of each trans(cid:173)
`mission channel (i.e., the SNR for each spatial subchannel
`for a MIMO system without OFDM, or the SNR for each
`spatial subchannel of each frequency subchannel for a
`MIMO system with OFDM). In this case, data may be
`adaptively processed at the transmitter (e.g., by selecting the
`proper coding and modulation scheme) for each transmis(cid:173)
`sion channel based on the channel's SNR.
`
`[0034] For a MIMO system not employing OFDM, TX
`MIMO processor 120 receives and demultiplexes the modu(cid:173)
`lation symbols from TX data processor 114 and provides a
`stream of modulation symbols for each transmit antenna,
`one modulation symbol per time slot. And for a MIMO
`system employing OFDM, TX MIMO processor 120 pro(cid:173)
`vides a stream of modulation symbol vectors for each
`transmit antenna, with each vector including NL modulation
`symbols for the NL frequency subchannels for a given time
`slot. Each stream of modulation symbols or modulation
`symbol vectors is received and modulated by a respective
`modulator (MOD) 122, and transmitted via an associated
`antenna 124.
`
`[0035] At receiver system 150, a number of receive anten(cid:173)
`nas 152 receive the transmitted signals and provide the
`received signals to respective demodulators (DEMOD) 154.
`Each demodulator 154 performs processing complementary
`
`to that performed at modulator 122. The modulation sym(cid:173)
`bols from all demodulators 154 are provided to a receive
`(RX) MIMO/data processor 156 and processed to recover
`the transmitted data streams. RX MIMO/data processor 156
`performs processing complementary to that performed by
`TX data processor 114 and TX MIMO processor 120 and
`provides decoded data to a data sink 160. The processing by
`receiver system 150 is described in further detail below.
`
`[0036] The spatial subchannels of a MIMO system (or
`more generally, the transmission channels in a MIMO sys(cid:173)
`tem with or without OFDM) typically experience different
`link conditions (e.g., different fading and multipath effects)
`and may achieve different SNR. Consequently, the capacity
`of the transmission channels may be different from channel
`to channel. This capacity may be quantified by the informa(cid:173)
`tion bit rate (i.e., the number of information bits per modu(cid:173)
`lation symbol) that may be transmitted on each transmission
`channel for a particular level of performance (e.g., a par(cid:173)
`ticular bit error rate (BER) or packet error rate (PER)).
`Moreover, the link conditions typically vary with time. As a
`result, the supported information bit rates for the transmis(cid:173)
`sion channels also vary with time. To more fully utilize the
`capacity of the transmission channels, CSI descriptive of the
`link conditions may be determined (typically at the receiver
`unit) and provided to the transmitter unit so that the pro(cid:173)
`cessing can be adjusted (or adapted) accordingly. The CSI
`may comprise any type of information that is indicative of
`the characteristics of the communication link and may be
`reported via various mechanisms, as described in further
`detail below. For simplicity, various aspects and embodi(cid:173)
`ments of the invention are described below wherein the CSI
`comprises SNR. Techniques to determine and utilize CSI to
`provide improved system performance are described below.
`
`MIMO Transmitter System with CSI Processing
`
`[0037] FIG. 2 is a block diagram of an embodiment of a
`MIMO transmitter system 110a, which does not utilize
`OFDM but is capable of adjusting its processing based on
`CSI available to the transmitter system (e.g., as reported by
`receiver system 150). Transmitter system 110a is one
`embodiment of the transmitter portion of system 110 in FIG.
`1. System 110a includes (1) a TX data processor 114a that
`receives and processes information bits to provide modula(cid:173)
`tion symbols and (2) a TX MIMO processor 120a that
`demultiplexes the modulation symbols for the NT transmit
`antennas.
`
`In the specific embodiment shown in FIG. 2, TX
`[0038]
`data processor 114a includes a demultiplexer 208 coupled to
`a number of channel data processors 210, one processor for
`each of the Nc transmission channels. Demultiplexer 208
`receives and demultiplexes the aggregate information bits
`into a number of (up to Nc) data streams, one data stream for
`each of the transmission channels to be used for data
`transmission. Each data stream is provided to a respective
`channel data processor 210.
`
`In the embodiment shown in FIG. 2, each channel
`[0039]
`data processor 210 includes an encoder 212, a channel
`interleaver 214, and a symbol mapping element 216.
`Encoder 212 receives and encodes the information bits in the
`received data stream in accordance with a particular encod(cid:173)
`ing scheme to provide coded bits. Channel interleaver 214
`interleaves the coded bits based on a particular interleaving
`
`SONY EX. 1007
`Page 14
`
`

`

`US 2003/0035491 Al
`
`Feb.20,2003
`
`4
`
`scheme to provide diversity. And symbol mapping element
`216 maps the interleaved bits into modulation symbols for
`the transmission channel used for transmitting the data
`stream.
`
`TABLE 1
`
`SNR
`Range
`
`# of Information Modulation #of Coded
`Bits/Symbol
`Symbol
`Bits/Symbol
`
`Coding
`Rate
`
`[0040] Pilot data (e.g., data of known pattern) may also be
`encoded and multiplexed with the processed information
`bits. The processed pilot data may be transmitted (e.g., in a
`time division multiplexed (TDM) manner) in all or a subset
`of the transmission channels used to transmit the informa(cid:173)
`tion bits. The pilot data may be used at the receiver to
`perform channel estimation, as described below.
`
`1.5-4.4
`4.4-6.4
`6.4-8.35
`8.35-10.4
`10.4-12.3
`12.3-14.15
`14.15-15.55
`15.55-17.35
`>17.35
`
`1.5
`2
`2.5
`3
`3.5
`4
`4.5
`5
`
`2
`2
`4
`4
`4
`
`QPSK
`QPSK
`16-QAM
`16-QAM
`16-QAM
`64-QAM
`64-QAM
`64-QAM
`64-QAM
`
`1/2
`3/4
`1/2
`5/8
`3/4
`7/12
`2/3
`3/4
`5/6
`
`[0041] As shown in FIG. 2, the data encoding, interleav(cid:173)
`ing, and modulation (