Spatial spreading in a multi-antenna communication system

• US 20050175115A1
• Filed: 12/09/2004
• Published: 08/11/2005
• Est. Priority Date: 12/17/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Walton, Jay Rodney, Howard, Steven J., Ketchum, John W., Zheng, Lizhong, Wallace, Mark S.
• Granted Patent: US 8,204,149 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04L 1/06 using space diversity

Abstract

Spatial spreading is performed in a multi-antenna system to randomize an “effective” channel observed by a receiving entity for each transmitted data symbol block. For a MIMO system, at a transmitting entity, data is processed (e.g., encoded, interleaved, and modulated) to obtain N_D data symbol blocks to be transmitted in N_M transmission spans, where N_D≧1 and N_M>1. The N_D blocks are partitioned into N_M data symbol subblocks, one subblock for each transmission span. A steering matrix is selected (e.g., in a deterministic or pseudo-random manner from among a set of L steering matrices, where L>1) for each subblock. Each data symbol subblock is spatially processed with the steering matrix selected for that subblock to obtain transmit symbols, which are further processed and transmitted via N_T transmit antennas in one transmission span. The N_D data symbol blocks are thus spatially processed with N_M steering matrices and observe an ensemble of channels.

Claims

1. A method of processing data for transmission in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

processing data to obtain at least one block of data symbols; and

performing spatial processing on the at least one block of data symbols with a plurality of steering matrices to obtain a plurality of sequences of transmit symbols for a plurality of transmit antennas, wherein the plurality of steering matrices randomize an effective MIMO channel observed by a receiving entity for the at least one block of data symbols.

2. The method of claim 1, wherein the processing data to obtain the at least one block of data symbols comprises

encoding data to generate at least one block of coded data, and

symbol mapping each block of coded data to obtain a corresponding block of data symbols.

3. The method of claim 1, further comprising:

partitioning the at least one block of data symbols into a plurality of subblocks of data symbols; and

selecting a steering matrix for each subblock of data symbols, and wherein the performing spatial processing on the at least one block of data symbols comprises performing spatial processing on each subblock of data symbols with the steering matrix selected for the subblock.

4. The method of claim 3, wherein the partitioning the at least one block of data symbols comprises

partitioning a single block of data symbols into a plurality of subblocks of data symbols.

5. The method of claim 3, wherein the partitioning the at least one block of data symbols comprises

partitioning a plurality of blocks of data symbols into a plurality of subblocks of data symbols.

6. The method of claim 3, wherein the partitioning the at least one block of data symbols comprises

partitioning the at least one block of data symbols into a plurality of subblocks of data symbols such that each subblock includes data symbols from each of the at least one block.

7. The method of claim 3, further comprising:

transmitting the plurality of subblocks of spatially processed data symbols in a plurality of transmission spans, one subblock in each transmission span.

8. The method of claim 3, further comprising:

transmitting each subblock of spatially processed data symbols from the plurality of transmit antennas in one symbol period.

9. The method of claim 3, further comprising:

transmitting each subblock of spatially processed data symbols from the plurality of transmit antennas on a respective group of at least one frequency subband.

10. The method of claim 1, further comprising:

transmitting the plurality of sequences of transmit symbols from the plurality of transmit antennas.

11. The method of claim 1, further comprising:

selecting the plurality of steering matrices from among a set of L steering matrices, where L is an integer greater than one.

12. The method of claim 1, further comprising:

selecting the plurality of steering matrices from among a set of L steering matrices in a deterministic manner, where L is an integer greater than one.

13. The method of claim 1, further comprising:

selecting the plurality of steering matrices from among a set of L steering matrices by cycling through the L steering matrices in sequential order, where L is an integer greater than one.

14. The method of claim 1, further comprising:

selecting the plurality of steering matrices from among a set of L steering matrices in a pseudo-random manner, where L is an integer greater than one.

15. The method of claim 3, further comprising:

selecting a different steering matrix for each of the plurality of subblocks of data symbols.

16. The method of claim 3, further comprising:

selecting a different order of L steering matrices for each subset of L subblocks among the plurality of subblocks, where L is an integer greater than one.

17. The method of claim 1, wherein the plurality of steering matrices are unitary matrices.

18. The method of claim 1, wherein the plurality of steering matrices have low correlation between any two steering matrices.

19. The method of claim 1, further comprising:

generating the plurality of steering matrices with a base matrix and a plurality of scalars.

20. The method of claim 1, further comprising:

generating the plurality of steering matrices based on an initial unitary matrix and a diagonal matrix of L-th roots of unity, where L is an integer greater than one.

21. The method of claim 1, further comprising:

generating the plurality of steering matrices based on a set of independent isotropically distributed unitary matrices.

22. The method of claim 1, further comprising:

processing the plurality of sequences of transmit symbols for orthogonal frequency division multiplexing (OFDM).

23. The method of claim 1, further comprising:

selecting a different steering matrix for each of a plurality of frequency subbands used for data transmission.

24. The method of claim 1, further comprising:

partitioning the at least one block of data symbols into a plurality of subblocks of data symbols, each subblock of data symbols being designated for transmission on a respective group of at least one frequency subband and from the plurality of transmit antennas, and wherein the performing spatial processing comprises performing spatial processing on the subblock of data symbols for each group of at least one frequency subband with a respective one of the plurality of steering matrices.

25. An apparatus in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

a data processor to process data to obtain at least one block of data symbols; and

a spatial processor to perform spatial processing on the at least one block of data symbols with a plurality of steering matrices to obtain a plurality of sequences of transmit symbols for a plurality of transmit antennas, wherein the plurality of steering matrices randomize an effective MIMO channel observed by a receiving entity for the at least one block of data symbols.

26. The apparatus of claim 25 wherein data is encoded to generate at least one block of coded data and wherein each block of coded data is mapped to obtain a corresponding block of data symbols.

27. The apparatus of claim 25, wherein the plurality of steering matrices are unitary matrices.

28. The apparatus of claim 25, wherein the spatial processor partitions the at least one block of data symbols into a plurality of subblocks of data symbols and performs spatial processing on each of the plurality of subblocks of data symbols with one of the plurality of steering matrices.

29. The apparatus of claim 28, further comprising:

a controller to select a steering matrix from among a set of L steering matrices for each of the plurality of subblocks of data symbols, where L is an integer greater than one.

30. The apparatus of claim 29, wherein the controller selects the plurality of steering matrices from among the set of L steering matrices in a deterministic manner.

31. The apparatus of claim 29, wherein the controller selects the plurality of steering matrices from among the set of L steering matrices in a pseudo-random manner.

32. The apparatus of claim 28, wherein the MIMO system utilizes orthogonal frequency division multiplexing (OFDM).

33. An apparatus in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

means for processing data to obtain at least one block of data symbols; and

means for performing spatial processing on the at least one block of data symbols with a plurality of steering matrices to obtain a plurality of sequences of transmit symbols for a plurality of transmit antennas, wherein the plurality of steering matrices randomize an effective MIMO channel observed by a receiving entity for the at least one block of data symbols.

34. The apparatus of claim 33, further comprising:

means for partitioning the at least one block of data symbols into a plurality of subblocks of data symbols; and

means for selecting a steering matrix for each of the plurality of subblocks of data symbols, and wherein the means for performing spatial processing comprises means for performing spatial processing on each of the plurality of subblocks of data symbols with the steering matrix selected for the subblock.

35. The apparatus of claim 33, wherein the plurality of steering matrices are unitary matrices.

36. The apparatus of claim 33, further comprising:

means for selecting the plurality of steering matrices from among a set of L steering matrices in a deterministic manner, where L is an integer greater than one.

37. The apparatus of claim 33, further comprising:

means for selecting the plurality of steering matrices from among a set of L steering matrices in a pseudo-random manner, where L is an integer greater than one.

38. A method of processing data for transmission in a wireless multiple-input single-output (MISO) communication system, comprising:

processing data to obtain a block of data symbols; and

performing spatial processing on the block of data symbols with a plurality of steering vectors to obtain a plurality of sequences of transmit symbols for a plurality of transmit antennas, wherein the plurality of steering vectors randomize an effective MISO channel observed by a receiving entity for the block of data symbols.

39. The method of claim 38, further comprising:

partitioning the block of data symbols into a plurality of subblocks of data symbols; and

selecting a steering vector for each of the plurality of subblocks of data symbols, and wherein the performing spatial processing on the block of data symbols comprises performing spatial processing on each of the plurality of subblocks of data symbols with the steering vector selected for the subblock.

40. The method of claim 38, wherein any pair of steering vectors among the plurality of steering vectors have low correlation.

41. The method of claim 38, further comprising:

generating the plurality of steering vectors with a base matrix and at least one scalar.

42. The method of claim 38, further comprising:

selecting the plurality of steering vectors from among a set of L steering vectors in a deterministic manner, where L is an integer greater than one.

43. The method of claim 38, further comprising:

selecting the plurality of steering vectors from among a set of L steering vectors in a pseudo-random manner, where L is an integer greater than one.

44. A method of receiving a data transmission in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

obtaining received data symbols for at least one data symbol block spatially processed with a plurality of steering matrices prior to transmission via a MIMO channel;

obtaining a channel response estimate for an effective MIMO channel formed by the MIMO channel and the plurality of steering matrices; and

performing receiver spatial processing on the received data symbols with the channel response estimate to obtain data symbol estimates for the at least one data symbol block.

45. The method of claim 44, further comprising:

selecting a steering matrix for each transmission span, and wherein the performing receiver spatial processing comprises performing receiver spatial processing on the received data symbols for each transmission span based on the steering matrix selected for the transmission span.

46. The method of claim 44, further comprising:

processing the data symbol estimates for the at least one data symbol block to obtain decoded data for the at least one data symbol block

47. The method of claim 44, wherein the plurality of steering matrices are unitary matrices.

48. An apparatus in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

a plurality of receiver units to obtain received data symbols for at least one data symbol block spatially processed with a plurality of steering matrices prior to transmission via a MIMO channel;

a channel estimator to obtain a channel response estimate for an effective MIMO channel formed by the MIMO channel and the plurality of steering matrices; and

a spatial processor to perform receiver spatial processing on the received data symbols with the channel response estimate to obtain data symbol estimates for the at least one data symbol block.

49. The apparatus of claim 48, wherein the plurality of steering matrices are unitary matrices.

50. An apparatus in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

means for obtaining received data symbols for at least one data symbol block spatially processed with a plurality of steering matrices prior to transmission via a MIMO channel;

means for obtaining a channel response estimate for an effective MIMO channel formed by the MIMO channel and the plurality of steering matrices; and

means for performing receiver spatial processing on the received data symbols with the channel response estimate to obtain data symbol estimates for the at least one data symbol block.

51. The apparatus of claim 50, further comprising:

means for selecting a steering matrix from among a set of L steering matrices for each transmission span, where L is an integer greater than one, and wherein the means for performing receiver spatial processing comprises means for performing receiver spatial processing on the received data symbols for each transmission span based on the steering matrix selected for the transmission span.

52. A method of receiving a data transmission in a wireless multiple-input single-output (MISO) communication system, comprising:

obtaining received data symbols for a data symbol block spatially processed with a plurality of steering vectors prior to transmission via a MISO channel;

obtaining a channel response estimate for an effective MISO channel formed by the MISO channel and the plurality of steering vectors; and

performing detection on the received data symbols with the channel response estimate to obtain data symbol estimates for the data symbol block.

53. The method of claim 52, further comprising:

selecting a steering vector from among a set of L steering vectors for each transmission span, where L is an integer greater than one, and wherein the channel response estimate for each transmission span is obtained based on the selected steering vector for the transmission span.