BROADCAST TRANSMISSION WITH SPATIAL SPREADING IN A MULTI-ANTENNA COMMUNICATION SYSTEM

• US 20080031374A1
• Filed: 10/10/2007
• Published: 02/07/2008
• Est. Priority Date: 12/17/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wallace, Mark, Howard, Steven, Ketchum, John, Walton, Jay
• Granted Patent: US 7,907,689 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• 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 receiving a broadcast transmission in a wireless multi-antenna communication system, comprising:

obtaining, via a plurality of receive antennas, received data symbols for at least one data symbol block spatially processed with a plurality of steering matrices prior to broadcast from a plurality of transmit antennas to a plurality of receiving entities;

obtaining a channel estimate for an effective multiple-input multiple-output (MIMO) channel formed by the plurality of steering matrices and a MIMO channel between the plurality of transmit antennas and the plurality of receive antennas; and

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

2. The method of claim 1, wherein the obtaining the channel estimate comprises

deriving a plurality of channel response matrices for a plurality of transmission spans in which the at least one data symbol block is broadcast, each channel response matrix including one of the plurality of steering matrices.

3. The method of claim 2, further comprising:

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

4. The method of claim 2, further comprising:

obtaining, via the plurality of receive antennas, received pilot symbols for a pilot broadcast from the plurality of transmit antennas to the plurality of receiving entities, and wherein the channel response matrix for each of the plurality of transmission spans is derived based on the received pilot symbols and the steering matrix used for the transmission span.

5. The method of claim 2, further comprising:

obtaining, via the plurality of receive antennas, received pilot symbols for a pilot spatially processed with the plurality of steering matrices prior to broadcast from the plurality of transmit antennas to the plurality of receiving entities, and wherein the channel response matrix for each of the plurality of transmission spans is derived based on the received pilot symbols.

6. The method of claim 1, wherein the performing receiver spatial processing comprises

performing receiver spatial processing on the received data symbols in accordance with a channel correlation matrix inversion (CCMI) technique.

7. The method of claim 1, wherein the performing receiver spatial processing comprises

performing receiver spatial processing on the received data symbols in accordance with a minimum mean square error (MMSE) technique.

8. The method of claim 1, wherein the performing receiver spatial processing comprises

performing receiver spatial processing on the received data symbols in accordance with a successive interference cancellation (SIC) technique.

9. The method of claim 1, further comprising:

performing detection on the data symbol estimates based on a transmit diversity scheme used on the at least one data symbol block prior to broadcast.

10. The method of claim 1, further comprising:

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

11. The method of claim 1, wherein the obtaining the channel estimate comprises

deriving a plurality of channel response matrices for a plurality of subbands used for broadcasting the at least one data symbol block, the channel response matrix for each frequency subband including a steering matrix used for the frequency subband.

12. An apparatus in a wireless multi-antenna communication system, comprising:

a plurality of receiver units to obtain, via a plurality of receive antennas, received data symbols for at least one data symbol block spatially processed with a plurality of steering matrices prior to broadcast from a plurality of transmit antennas to a plurality of receiving entities;

a channel estimator to obtain a channel estimate for an effective multiple-input multiple-output (MIMO) channel formed by the plurality of steering matrices and a MIMO channel between the plurality of transmit antennas and the plurality of receive antennas; and

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

13. The apparatus of claim 12, wherein each of the plurality of steering matrices includes a plurality of columns, and wherein the at least one data symbol block is broadcast via a plurality of spatial channels of the effective MIMO channel.

14. The apparatus of claim 12, wherein each of the plurality of steering matrices includes a single column, and wherein the at least one data symbol block is broadcast via a single spatial channel of the effective MIMO channel.

15. The apparatus of claim 12, wherein the spatial processor performs receiver spatial processing based on a channel correlation matrix inversion (CCMI) technique, a minimum mean square error (MMSE) technique, or a successive interference cancellation (SIC) technique.

16. The apparatus of claim 12, wherein the spatial processor performs transmit diversity processing on the data symbol estimates for the at least one data symbol block.

17. An apparatus in a wireless multi-antenna communication system, comprising:

means for obtaining, via a plurality of receive antennas, received data symbols for at least one data symbol block spatially processed with a plurality of steering matrices prior to broadcast from a plurality of transmit antennas to a plurality of receiving entities;

means for obtaining a channel estimate for an effective multiple-input multiple-output (MIMO) channel formed by the plurality of steering matrices and a MIMO channel between the plurality of transmit antennas and the plurality of receive antennas; and

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

18. The apparatus of claim 17, wherein each of the plurality of steering matrices includes a plurality of columns, and wherein the at least one data symbol block is broadcast via a plurality of spatial channels of the effective MIMO channel.

19. The apparatus of claim 17, wherein each of the plurality of steering matrices includes a single column, and wherein the at least one data symbol block is broadcast via a single spatial channel of the effective MIMO channel.

20. The apparatus of claim 17, wherein the means for performing receiver spatial processing comprises means for performing receiver spatial processing based on a channel correlation matrix inversion (CCMI) technique, a minimum mean square error (MMSE) technique, or a successive interference cancellation (SIC) technique.

21. A method of receiving a broadcast transmission in a wireless multi-antenna communication system, comprising:

obtaining, via a single receive antenna, received data symbols for a data symbol block spatially processed with a plurality of steering vectors prior to broadcast from a plurality of transmit antennas to a plurality of receiving entities;

obtaining a channel estimate for an effective multiple-input single-output (MISO) channel formed by the plurality of steering vectors and a MISO channel between the plurality of transmit antennas and the single receive antenna; and

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

22. The method of claim 21, wherein the obtaining the channel estimate comprises

deriving a plurality of channel response estimates for a plurality of transmission spans, the channel response estimate for each transmission span including a steering vector used for the transmission span.

23. The method of claim 21, further comprising:

obtaining, via the single receive antenna, received pilot symbols for a pilot broadcast from the plurality of transmit antennas to the plurality of receiving entities, and wherein the channel estimate is obtained based on the received pilot symbols and the plurality of steering vectors.

24. The method of claim 21, further comprising:

obtaining, via the single receive antenna, received pilot symbols for a pilot spatially processed with the plurality of steering vectors prior to broadcast from the plurality of transmit antennas to the plurality of receiving entities, and wherein the channel estimate is obtained based on the received pilot symbols.

25. The method of claim 21, wherein the performing detection comprises

performing matched filtering, equalization, or both matched filtering and equalization on the received data symbols with the channel estimate to obtain data symbol estimates for the data symbol block.

26. The method of claim 21, wherein the obtaining the channel estimate comprises obtaining a channel response estimate for each of a plurality of frequency subbands with a steering vector used for the subband.

27. An apparatus in a wireless multi-antenna communication system, comprising:

a receiver unit to obtain, via a single receive antenna, received data symbols for a data symbol block spatially processed with a plurality of steering vectors prior to broadcast from a plurality of transmit antennas to a plurality of receiving entities;

a channel estimator to obtain a channel estimate for an effective multiple-input single-output (MISO) channel formed by the plurality of steering vectors and a MISO channel between the plurality of transmit antennas and the single receive antenna; and

a detector to perform detection on the received data symbols with the channel estimate to obtain data symbol estimates for the data symbol block.

28. The apparatus of claim 27, wherein the channel estimator obtains a channel response estimate for each of a plurality of transmission spans in which the data symbol block is broadcast, the channel response estimate for each transmission span including a steering vector used for the transmission span.

29. The apparatus of claim 27, wherein the channel estimator obtains the channel estimate based on received pilot symbols and the plurality of steering vectors.

30. The apparatus of claim 27, wherein the detector performs matched filtering, equalization, or both matched filtering and equalization.

31. An apparatus in a wireless multi-antenna communication system, comprising:

means for obtaining, via a single receive antenna, received data symbols for a data symbol block spatially processed with a plurality of steering vectors prior to broadcast from a plurality of transmit antennas to a plurality of receiving entities;

means for obtaining a channel estimate for an effective multiple-input single-output (MISO) channel formed by the plurality of steering vectors and a MISO channel between the plurality of transmit antennas and the single receive antenna; and

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

32. The apparatus of claim 31, wherein the means for obtaining the channel estimate comprises means for obtaining a channel response estimate for each of a plurality of transmission spans in which the at least one data symbol block is broadcast, the channel response estimate for each transmission span including a steering vector used for the transmission span.