Beam-steering and beam-forming for wideband MIMO/MISO systems

• US 20040042439A1
• Filed: 08/27/2002
• Published: 03/04/2004
• Est. Priority Date: 08/27/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Howard, Steven J., Ketchum, John W., Walton, Jay Rod, Wallace, Mark, Menon, Murali Paravath
• Granted Patent: US 6,940,917 B2
• Time in Patent Office: Days
• US Class Current: 370/343
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/043 using best eigenmode, e.g. beam forming or beam steering
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03802 Signalling on the reverse channel
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0246 with factorisation
• CPC Class Codes: H04L 25/0248 Eigen-space methods
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 5/0025 Spatial division following the spatial signature of the channel
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0085 when channel conditions change
• CPC Class Codes: H04L 5/0096 Indication of changes in allocation
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

Techniques to perform beam-steering and beam-forming to transmit data on a single eigenmode in a wideband multiple-input channel. In one method, a steering vector is obtained for each of a number of subbands. Depending on how the steering vectors are defined, beam-steering or beam-forming can be achieved for each subband. The total transmit power is allocated to the subbands based on a particular power allocation scheme (e.g., full channel inversion, selective channel inversion, water-filling, or uniform). A scaling value is then obtained for each subband based on its allocated transmit power. Data to be transmitted is coded and modulated to provide modulation symbols. The modulation symbols to be transmitted on each subband are scaled with the subband'"'"'s scaling value and further preconditioned with the subband'"'"'s steering vector. A stream of preconditioned symbols is then formed for each transmit antenna.

Claims

1. A method for processing data for transmission via a wideband multiple-input channel, comprising:

obtaining a steering vector for each of a plurality of subbands, wherein each steering vector includes a plurality of elements for a plurality of transmit antennas; and

preconditioning modulation symbols to be transmitted on each subband with the steering vector for the subband.

2. The method of claim 1, wherein each steering vector achieves beam-steering for the associated subband.

3. The method of claim 1, wherein the elements of each steering vector have equal amplitude.

4. The method of claim 1, wherein each steering vector achieves beam-forming for the associated subband.

5. The method of claim 1, further comprising:

obtaining a plurality of scaling values for the plurality of subbands; and

scaling the modulation symbols for each subband with the scaling value for the subband.

6. The method of claim 5, wherein the scaling values for the subbands are determined based on gains for the subbands provided by the steering vectors.

7. The method of claim 5, wherein the scaling values for the subbands are determined based on transmit powers allocated to the subbands.

8. The method of claim 7, wherein the transmit powers are allocated to the subbands based on full channel inversion.

9. The method of claim 7, wherein the transmit powers are allocated to the subbands based on selective channel inversion.

10. The method of claim 7, wherein the transmit powers are allocated to the subbands based on uniform power allocation.

11. The method of claim 7, wherein the transmit powers are allocated to the subbands based on water-filling power allocation.

12. The method of claim 1, wherein the multiple-input channel is a multiple-input multiple-output (MIMO) channel.

13. The method of claim 12, wherein the steering vector for each subband is derived based on an eigenvector corresponding to a principal eigenmode.

14. The method of claim 1, wherein the multiple-input channel is a multiple-input single-output (MISO) channel.

15. The method of claim 1, further comprising:

coding and modulating data based on a common coding and modulation scheme to provide the modulation symbols.

16. The method of claim 1, further comprising:

forming a stream of preconditioned symbols for each transmit antenna; and

processing each stream of preconditioned symbols to provide a modulated signal for transmission from a respective transmit antenna.

17. The method of claim 1, wherein the wideband system implements orthogonal frequency division multiplexing (OFDM), and wherein the plurality of subbands correspond to orthogonal subbands provided by OFDM.

18. In a multiple-input communication system that implements orthogonal frequency division multiplexing (OFDM), a method for processing data for transmission via a multiple-input channel comprising:

obtaining a steering vector for each of a plurality of subbands, wherein each steering vector includes a plurality of elements for a plurality of transmit antennas;

obtaining a plurality of scaling values for the plurality of subbands;

scaling modulation symbols to be transmitted on each subband with the scaling value for the subband;

preconditioning the scaled modulation symbols for each subband with the steering vector for the subband; and

forming a stream of preconditioned symbols for each transmit antenna.

19. The method of claim 18, wherein each steering vector achieves beam-steering for the associated subband.

20. The method of claim 18, wherein the scaling values for the subbands are determined based on selective channel inversion.

21. A transmitter unit in a multiple-input communication system, comprising:

a TX data processor operative to code and modulate data based on one or more coding and modulation schemes to provide modulation symbols; and

a TX spatial processor operative to obtain a steering vector for each of a plurality of subbands, precondition the modulation symbols to be transmitted on each subband with the steering vector for the subband, and provide preconditioned symbols for transmission via a single eigenmode of a multiple-input channel.

22. The transmitter unit of claim 21, wherein the TX spatial processor is further operative to allocate total transmit power to the plurality of subbands.

23. The transmitter unit of claim 22, wherein the TX spatial processor is further operative to determine a scaling value for each subband based on the transmit power allocated to the subband, and to scale the modulation symbols for each subband with the scaling value for the subband.

24. The transmitter unit of claim 21, wherein each steering vector achieves beam-steering for the associated subband.

25. A transmitter unit in a multiple-input communication system that implements orthogonal frequency division multiplexing (OFDM), comprising:

a TX data processor operative to code and modulate data based on a common coding and modulation scheme to provide modulation symbols; and

a TX spatial processor operative to

obtain a steering vector for each of a plurality of subbands, wherein each steering vector includes a plurality of elements for a plurality of transmit antennas,

obtain a plurality of scaling values for the plurality of subbands,

scale the modulation symbols to be transmitted on each subband with the scaling value for the subband,

precondition the scaled modulation symbols for each subband with the steering vector for the subband, and

provide preconditioned symbols for transmission via a single eigenmode of a multiple-input channel.

26. An apparatus operative to process data for transmission via a multiple-input channel, comprising:

means for obtaining a steering vector for each of a plurality of subbands, wherein each steering vector includes a plurality of elements for a plurality of transmit antennas; and

means for preconditioning modulation symbols to be transmitted on each subband with the steering vector for the subband.

27. The apparatus of claim 26, further comprising:

means for obtaining gains for the subbands provided by the steering vectors;

means for allocating total transmit power to the subbands based at least in part on the gains;

means for determining scaling values for the subbands based on transmit powers allocated to the subbands; and

means for scaling the modulation symbols for each subband with the scaling value for the subband.