Broadcast transmission with spatial spreading in a multi-antenna communication system

• US 7,899,131 B2
• Filed: 10/10/2007
• Issued: 03/01/2011
• Est. Priority Date: 12/17/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Howard, Steven J., Ketchum, John W., Walton, J. Rodney, Wallace, Mark S.
• Primary Examiner(s): Ghebretinsae; Temesghen
• Application Number:
  US11/870,380
• Publication Number:
  US 20080031372A1
• Time in Patent Office: 1,238 Days
• Field of Search: 375/299, 375/260, 375/295, 375/296, 375/130, 375/267, 370/203, 370/204, 455/101
• US Class Current: 375/295
• CPC Class Codes: H04B 7/043 using best eigenmode, e.g. beam forming or beam steering
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0678 using different spreading codes between antennas code allocation H04J13/16
• CPC Class Codes: H04B 7/068 using space frequency diversity space-frequency coding H04L1/0606
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 25/03866 using scrambling
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

An access point in a multi-antenna system broadcasts data using spatial spreading to randomize an “effective” channel observed by each user terminal for each block of data symbols broadcast by the access point. At the access point, data is coded, interleaved, and modulated to obtain N_D data symbol blocks to be broadcast in N_M transmission spans, where N_D≧1 and N_M>1. The N_D data symbol 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) 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 broadcast via N_T transmit antennas and in one transmission span to user terminals within a broadcast coverage area.

Claims

1. A method of broadcasting data from a wireless multi-antenna transmitter, comprising:

selecting at least two steering matrices for transmission of at least one block of data symbols obtained from at least one block of data, wherein the at least two steering matrices are provided to randomize an effective channel observed by each of a plurality of receiving entities for the at least one block of data symbols;

performing spatial processing on the at least one block of data symbols with each of the at least two steering matrices to obtain a plurality of sequences of transmit symbols, wherein the spatial processing comprises obtaining transmit symbols to be sent from a plurality of access point antennas in a transmission span by processing data symbols to be sent in the transmission span with a steering matrix selected for the transmission span; and

broadcasting one or more signals comprising the plurality of sequences of transmit symbols from a plurality of transmit antennas.

2. The method of claim 1, further comprising:

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

wherein the selecting at least two steering matrices comprises selecting a steering matrix for each of the plurality of subblocks of data symbols; and

wherein performing spatial processing comprises performing spatial processing for each of the plurality of subblocks of data symbols with a different one of the at least two steering matrices.

3. The method of claim 1, wherein the processing the at least one block of data comprises, for each block of data:

encoding the block of data in accordance with a coding scheme to obtain a block of coded data;

interleaving the block of coded data to obtain a block of interleaved data; and

symbol mapping the block of interleaved data in accordance with a modulation scheme to obtain the block of data symbols.

4. The method of claim 1, further comprising:

determining a data rate for each of the at least one block of data based on expected channel conditions for the plurality of receiving entities.

5. The method of claim 1, further comprising:

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

6. The method of claim 1, further comprising:

generating a plurality of steering matrices as unitary matrices having orthogonal columns, and wherein selecting comprises selecting the at least two matrices from the plurality of steering matrices.

25. The method of claim 1, wherein the spatial processing is performed in accordance with the following formula:

x_mino(m)=V(m)·

s(m) ,

where s(m) is an N_S×

1 vector with N_S data symbols to be sent in transmission span m;

V(m) is an N_ap×

N_S steering matrix for transmission span m; and

x_mimo(m) is an N_ap×

1 vector with N_ap transmit symbols to be sent from the N_ap access point antennas in transmission span m.

7. A wireless multi-antenna transmitter, comprising:

a processor configured to perform spatial processing on the at least one block of data symbols, obtained from at least one block of data, with at least two steering matrices to obtain a plurality of sequences of transmit symbols each processed with a different one of the at least two steering matrices, wherein the plurality of steering matrices randomize an effective channel observed by each of a plurality of receiving entities for the at least one block of data symbols, wherein the spatial processing comprises obtaining transmit symbols to be sent from a plurality of access point antennas in a transmission span by processing data symbols to be sent in the transmission span with a steering matrix for the transmission span; and

a plurality of transmitter units configured to broadcast the plurality of sequences of transmit symbols from a plurality of transmit antennas to the plurality of receiving entities in the system.

8. The transmitter of claim 7, wherein the processor is configured to partition 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 a different one of the at least two steering matrices.

9. The transmitter of claim 7, further comprising a controller configured to select the at least two steering matrices 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.

10. The transmitter of claim 7, wherein each of the plurality of steering matrices includes a plurality of orthogonal columns, and wherein the processor configures the at least one block of data symbols for broadcast via a plurality of spatial channels.

11. The transmitter of claim 7, wherein each of the plurality of steering matrices includes a single column, and wherein the processor configures the at least one block of data symbols for broadcast via a single spatial channel.

12. The transmitter of claim 7, wherein the at least two steering matrices are unitary matrices having orthogonal columns.

26. The transmitter of claim 7, wherein the spatial processing is performed in accordance with the following formula:

x_mimo(m)=V(m)·

s(m),

where s(m) is an N_S×

1 vector with N_S data symbols to be sent in transmission span m;

V(m) is an N_ap×

N_S steering matrix for transmission span m; and

x_mimo(m) is an N_ap×

1 vector with N_ap transmit symbols to be sent from the N_ap access point antennas in transmission span m.

13. A wireless multi-antenna transmitter, comprising:

means for selecting at least two steering matrices for transmission of the at least one block of data symbols obtained from at least one block of data, wherein the at least two steering matrices are provided to randomize an effective channel observed by each of a plurality of receiving entities for the at least one block of data symbols;

means for performing spatial processing on the at least one block of data symbols with each of the at least two steering matrices to obtain a plurality of sequences of transmit symbols, wherein the spatial processing comprises obtaining transmit symbols to be sent from a plurality of access point antennas in a transmission span by processing data symbols to be sent in the transmission span with a steering matrix for the transmission span; and

means for broadcasting the plurality of sequences of transmit symbols from a plurality of transmit antennas.

14. The transmitter of claim 13, further comprising:

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

wherein the means for selecting the at least two steering matrices are configured to select 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 for each of the plurality of subblocks of data symbols with a different one of the at least two steering matrices.

15. The transmitter of claim 13, wherein the means for processing the at least one block of data comprises, for each block of data:

means for encoding the block of data in accordance with a coding scheme to obtain a block of coded data;

means for interleaving the block of coded data to obtain a block of interleaved data; and

means for symbol mapping the block of interleaved data in accordance with a modulation scheme to obtain the block of data symbols.

16. The transmitter of claim 13, further comprising:

means for determining a data rate for each of the at least one block of data based on expected channel conditions for the plurality of receiving entities.

17. The transmitter of claim 13, further comprising:

means for selecting the at least two steering matrices from among a set of L steering matrices, where L is an integer greater than one.

18. The transmitter of claim 13, further comprising:

means for generating a plurality of steering matrices as unitary matrices having orthogonal columns, and wherein the means for selecting comprises means for selecting the at least two matrices from the plurality of steering matrices.

27. The transmitter of claim 13, wherein the spatial processing is performed in accordance with the following formula:

x_mimo(m)=V(m)·

s(m),

where s(m) is an N_S×

1 vector with N_S data symbols to be sent in transmission span m;

V(m) is an N_ap×

N_S steering matrix for transmission span m; and

x_mimo(m) is an N_ap×

1 vector with N_ap transmit symbols to be sent from the N_ap access point antennas in transmission span m.

19. A memory unit including stored software codes that are utilized by one or more processors, the software codes comprising:

code for selecting at least two steering matrices for transmission of the at least one block of data symbols obtained from at least one block of data, wherein the at least two steering matrices are provided to randomize an effective channel observed by each of a plurality of receiving entities for the at least one block of data symbols;

code for performing spatial processing on the at least one block of data symbols with each of the at least two steering matrices to obtain a plurality of sequences of transmit symbols, wherein the spatial processing comprises obtaining transmit symbols to be sent from a plurality of access point antennas in a transmission span by processing data symbols to be sent in the transmission span with a steering matrix for the transmission span; and

code for broadcasting one or more signals comprising the plurality of sequences of transmit symbols from a plurality of transmit antennas.

20. The memory unit of claim 19, wherein the software codes further comprise:

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

code for selecting a steering matrix for each of the plurality of subblocks of data symbols; and

wherein the code for performing spatial processing comprises codes for performing spatial processing for each of the plurality of subblocks of data symbols with a different one of the at least two steering matrices.

21. The memory unit of claim 19, wherein the code for processing the at least one block of data comprises, for each block of data:

code for encoding the block of data in accordance with a coding scheme to obtain a block of coded data;

code for interleaving the block of coded data to obtain a block of interleaved data; and

code for symbol mapping the block of interleaved data in accordance with a modulation scheme to obtain the block of data symbols.

22. The memory unit of claim 19, wherein the software codes further comprise:

code for determining a data rate for each of the at least one block of data based on expected channel conditions for the plurality of receiving entities.

23. The memory unit of claim 19, wherein the software codes further comprise:

code for selecting the at least two steering matrices from among a set of L steering matrices, where L is an integer greater than one.

24. The memory unit of claim 19, wherein the software codes further comprise:

code for generating a plurality of steering matrices as unitary matrices having orthogonal columns, and wherein the means for selecting comprises means for selecting the at least two matrices from the plurality of steering matrices.

28. The memory unit of claim 19, wherein the spatial processing is performed in accordance with the following formula:

x_mimo(m)=V(m)·

s(m),

where s(m) is an N_S×

1 vector with N_S data symbols to be sent in transmission span m;

V(m) is an N_ap×

N_S steering matrix for transmission span m; and

x_mimo(m) is an N_ap×

1 vector with N_ap transmit symbols to be sent from the N_ap access point antennas in transmission span m.