STEERING DIVERSITY FOR AN OFDM-BASED MULTI-ANTENNA COMMUNICATION SYSTEM

• US 20080273617A1
• Filed: 07/18/2008
• Published: 11/06/2008
• Est. Priority Date: 05/07/2004
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Walton, Jay Rodney, Howard, Steven J., Lundby, Stein A.
• Application Number:
  US12/176,306
• Publication Number:
  US 20080273617A1
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 27/2602 Signal structure

Abstract

A transmitting entity uses different steering vectors for different subbands to achieve steering diversity. Each steering vector defines or forms a beam for an associated subband. Any steering vector may be used for steering diversity. The steering vectors may be defined such that the beams vary in a continuous instead of abrupt manner across the subbands. This may be achieved by applying continuously changing phase shifts across the subbands for each transmit antenna. As an example, the phase shifts may change in a linear manner across the subbands for each transmit antenna, and each antenna may be associated with a different phase slope. The application of linearly changing phase shifts to modulation symbols in the frequency domain may be achieved by either delaying or circularly shifting the corresponding time-domain samples.

Claims

1. A method of transmitting data in a wireless communication system, comprising:

obtaining input symbols to be transmitted on a plurality of frequency subbands of a plurality of antennas;

modifying an input symbol for each frequency subband of each antenna with a phase shift selected for the frequency subband and the respective antenna to generate a phase-shifted symbol for the frequency subband and the respective antenna; and

processing phase-shifted symbols for the plurality of frequency subbands of each antenna to obtain a sequence of samples for the respective antenna.

2. The method of claim 1, further comprising:

applying linearly varying phase shifts across the plurality of frequency subbands for each antenna.

3. The method of claim 1, further comprising:

applying a different phase slope across the plurality of frequency subbands for each antenna.

4. The method of claim 1, further comprising:

applying continuously varying phase shifts across the plurality of frequency subbands for each antenna.

5. The method of claim 4, further comprising:

determining the continuously varying phase shifts across the frequency subbands for each antenna based on a function selected for the respective antenna.

6. The method of claim 1, wherein the processing the phase-shifted symbols comprises

performing orthogonal frequency division multiplexing (OFDM) modulation on the phase-shifted symbols for the plurality of frequency subbands of each antenna to obtain the sequence of samples for the respective antenna.

7. An apparatus in a wireless communication system, comprising:

a spatial processor to obtain input symbols to be transmitted on a plurality of frequency subbands of a plurality of antennas and to modify an input symbol for each frequency subband of each antenna with a phase shift selected for the frequency subband and the respective antenna to generate a phase-shifted symbol for the frequency subband and the respective antenna; and

a modulator to process phase-shifted symbols for the plurality of frequency subbands of each antenna to obtain a sequence of samples for the respective antenna.

8. The apparatus of claim 7, wherein the spatial processor applies linearly varying phase shifts across the plurality of frequency subbands for each antenna.

9. The apparatus of claim 7, wherein the spatial processor applies a different phase slope across the plurality of frequency subbands for each antenna.

10. The apparatus of claim 7, wherein the spatial processor applies continuously varying phase shifts across the plurality of frequency subbands for each antenna.

11. An apparatus in a wireless communication system, comprising:

means for obtaining input symbols to be transmitted on a plurality of frequency subbands of a plurality of antennas;

means for modifying an input symbol for each frequency subband of each antenna with a phase shift selected for the frequency subband and the respective antenna to generate a phase-shifted symbol for the frequency subband and the respective antenna; and

means for processing phase-shifted symbols for the plurality of frequency subbands of each antenna to obtain a sequence of samples for the respective antenna.

12. The apparatus of claim 11, further comprising:

means for applying linearly varying phase shifts across the plurality of frequency subbands for each antenna.

13. The apparatus of claim 11, further comprising:

means for applying a different phase slope across the plurality of frequency subbands for each antenna.

14. The apparatus of claim 11, further comprising:

means for applying continuously varying phase shifts across the plurality of frequency subbands for each antenna.

15. A computer-program apparatus for processing data in a wireless communication system comprising a computer readable medium having instructions stored thereon, the instructions being executable by one or more processors and the instructions comprising:

instructions for processing data to obtain an input sequence of time-domain samples;

instructions for obtaining input symbols to be transmitted on a plurality of frequency subbands of a plurality of antennas;

instructions for modifying an input symbol for each frequency subband of each antenna with a phase shift selected for the frequency subband and the respective antenna to generate a phase-shifted symbol for the frequency subband and the respective antenna; and

instructions for processing phase-shifted symbols for the plurality of frequency subbands of each antenna to obtain a sequence of samples for the respective antenna.

16. The computer-program apparatus of claim 15, further comprising:

instructions for applying linearly varying phase shifts across the plurality of frequency subbands for each antenna.

17. The computer-program apparatus of claim 15, further comprising:

instructions for applying a different phase slope across the plurality of frequency subbands for each antenna.

18. The computer-program apparatus of claim 15, further comprising:

instructions for applying continuously varying phase shifts across the plurality of frequency subbands for each antenna.