Steering diversity for an OFDM-based multi-antenna communication system

• US 8,285,226 B2
• Filed: 02/24/2005
• Issued: 10/09/2012
• Est. Priority Date: 05/07/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lundby, Stein A., Howard, Steven J., Walton, Jay Rodney
• Primary Examiner(s): HANNON, CHRISTIAN A
• Application Number:
  US11/066,771
• Publication Number:
  US 20050249174A1
• Time in Patent Office: 2,784 Days
• Field of Search: 455/103, 455/104, 455/105, 455110-113, 375/260, 375/267, 375/299
• US Class Current: 455/101
• 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:

performing an inverse discrete Fourier transform on a plurality of input symbols for a plurality of frequency subbands to obtain a plurality of time-domain samples, wherein each frequency subband is associated with a different steering vector of a plurality of steering vectors, and

repeating a portion of the plurality of time-domain samples to obtain an input sequence of time-domain samples;

delaying the input sequence of time-domain samples by different sample period amounts to generate a plurality of output sequences of time-domain samples for a plurality of antennas, wherein each different sample period amount is associated with a different steering vector of the plurality of steering vectors; and

transmitting the plurality of output sequences from the plurality of antennas.

2. The method of claim 1, wherein the generating the plurality of output sequences of time-domain samples comprises:

delaying the input sequence by different integer numbers of sample periods to generate the plurality of output sequences.

3. The method of claim 1, wherein the generating the plurality of output sequences of time-domain samples comprises:

delaying the input sequence by different fractional amounts of a sample period to generate the plurality of output sequences.

4. The method of claim 1, wherein delaying the input sequence of time-domain samples by different sample period amounts comprises processing the time-domain samples to provide time delays corresponding to the different amounts in the analog domain prior to transmitting the plurality of output sequences from the plurality of antennas.

5. The method of claim 1, wherein the plurality of steering vectors are defined to vary beams in a continuous manner across the plurality of frequency subbands.

6. The method of claim 1, wherein the plurality of steering vectors are defined to change the different sample period amounts in a linear manner across the plurality of frequency subbands.

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

performing an inverse discrete Fourier transform on a plurality of input symbols for a plurality of frequency subbands to obtain a plurality of time-domain samples, wherein each frequency subband is associated with a different steering vector of a plurality of steering vectors, and

repeating a portion of the plurality of time-domain samples to obtain an input sequence of time-domain samples;

delaying the input sequence of time-domain samples by different amounts to generate a plurality of output sequences of time-domain samples for a plurality of antennas, wherein each different amount is associated with a different steering vector of the plurality of steering vectors; and

transmitting the plurality of output sequences from the plurality of antennas starting at different times.

8. The method of claim 7, wherein the plurality of steering vectors are defined to vary beams in a continuous manner across the plurality of frequency subbands.

9. The method of claim 7, wherein the plurality of steering vectors are defined to change the different amounts in a linear manner across the plurality of frequency subbands.

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

a modulator to process data to obtain an input sequence of time-domain samples, wherein the modulator performs an inverse discrete Fourier transform on a plurality of input symbols for a plurality of frequency subbands to obtain a plurality of time-domain samples and further repeats a portion of the plurality of time-domain samples to obtain the input sequence of time-domain samples, wherein each frequency subband is associated with a different steering vector of a plurality of steering vectors;

a processor to generate a plurality of output sequences of time-domain samples for a plurality of antennas by temporally modifying the input sequence of time-domain samples, wherein the processor delays the input sequence by different sample period amounts to generate the plurality of output sequences, wherein each different sample period amount is associated with a different steering vector of the plurality of steering vectors; and

a plurality of transmitter units to transmit the plurality of output sequences from the plurality of antennas.

11. The apparatus of claim 10, wherein the processor comprises:

a plurality of delay unit to delay the input sequence by different fractional amounts of a sample period to generate the plurality of output sequences.

12. The apparatus of claim 10, wherein the processor delays the input sequence by different amounts to generate the plurality of output sequences by providing time delays corresponding to the different sample period amounts in the analog domain.

13. The apparatus of claim 10, wherein the plurality of steering vectors are defined to vary beams in a continuous manner across the plurality of frequency subbands.

14. The apparatus of claim 10, wherein the plurality of steering vectors are defined to change the different sample period amounts in a linear manner across the plurality of frequency subbands.

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

means for processing data to obtain an input sequence of time-domain samples, wherein the means for processing the data comprises

means for performing an inverse discrete Fourier transform on a plurality of input symbols for a plurality of frequency subbands to obtain a plurality of time-domain samples, wherein each frequency subband is associated with a different steering vector of a plurality of steering vectors;

means for repeating a portion of the plurality of time-domain samples to obtain the input sequence of time-domain samples;

means for generating a plurality of output sequences of time-domain samples for a plurality of antennas by temporally modifying the input sequence of time-domain samples, wherein the means for generating the plurality of output sequences of time-domain samples comprises;

means for delaying the input sequence by different sample period amounts to generate the plurality of output sequences, wherein each different sample period amount is associated with a different steering vector of the plurality of steering vectors; and

means for transmitting the plurality of output sequences from the plurality of antennas.

16. The apparatus of claim 15, wherein the means for delaying the input sequence by different amounts to generate the plurality of output sequences provides time delays corresponding to the different sample period amounts in the analog domain.

17. The apparatus of claim 15, wherein the plurality of steering vectors are defined to vary beams in a continuous manner across the plurality of frequency subbands.

18. The apparatus of claim 15, wherein the plurality of steering vectors are defined to change the different sample period amounts in a linear manner across the plurality of frequency subbands.

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

means for processing data to obtain an input sequence of time-domain samples, wherein the means for processing the data comprises

means for performing an inverse discrete Fourier transform on a plurality of input symbols for a plurality of frequency subbands to obtain a plurality of time-domain samples, wherein each frequency subband is associated with a different steering vector of a plurality of steering vectors, and

means for repeating a portion of the plurality of time-domain samples to obtain the input sequence of time-domain samples;

means for generating a plurality of output sequences of time-domain samples for a plurality of antennas by temporally modifying the input sequence of time-domain samples, wherein the means for generating the plurality of output sequences of time-domain samples comprises;

means for delaying the input sequence by different amounts to generate the plurality of output sequences, wherein each different amount is associated with a different steering vector of the plurality of steering vectors; and

means for transmitting the plurality of output sequences from the plurality of antennas starting at different times.

20. The apparatus of claim 19, wherein the plurality of steering vectors are defined to vary beams in a continuous manner across the plurality of frequency subbands.

21. The apparatus of claim 19, wherein the plurality of steering vectors are defined to change the different sample period amounts in a linear manner across the plurality of frequency subbands.

22. A computer-program apparatus for processing data for transmission in a wireless communication system comprising a memory unit 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, wherein the computer-executable instructions for processing the data comprise;

instructions for performing an inverse discrete Fourier transform on a plurality of input symbols for a plurality of frequency subbands to obtain a plurality of time-domain samples, wherein each frequency subband is associated with a different steering vector of a plurality of steering vectors, and

instructions for repeating a portion of the plurality of time-domain samples to obtain the input sequence of time-domain samples;

instructions for generating a plurality of output sequences of time-domain samples for a plurality of antennas by temporally modifying the input sequence of time-domain samples, wherein the computer-executable instructions for generating the plurality of output sequences of time-domain samples comprise

instructions for delaying the input sequence by different sample period amounts to generate the plurality of output sequences, wherein each different sample period amount is associated with a different steering vector of the plurality of steering vectors; and

instructions for transmitting the plurality of output sequences from the plurality of antennas.

23. The computer-program apparatus of claim 22, wherein the computer-executable instructions for generating the plurality of output sequences of time-domain samples comprise:

instructions for delaying the input sequence by different integer numbers of sample periods to generate the plurality of output sequences.

24. The computer-program apparatus of claim 22, wherein the computer-executable instructions for generating the plurality of output sequences of time-domain samples comprise:

instructions for delaying the input sequence by different fractional amounts of a sample period to generate the plurality of output sequences.

25. The computer-program apparatus of claim 22, wherein the instructions for delaying the input sequence by different amounts to generate the plurality of output sequences comprise instructions for providing time delays corresponding to the different sample period amounts in the analog domain.

26. The computer-program apparatus of claim 22, wherein the plurality of steering vectors are defined to vary beams in a continuous manner across the plurality of frequency subbands.

27. The computer-program apparatus of claim 22, wherein the plurality of steering vectors are defined to change the different sample period amounts in a linear manner across the plurality of frequency subbands.

28. A computer-program apparatus for processing data for transmission in a wireless communication system comprising a memory unit 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, wherein the computer-executable instructions for processing the data comprise;

instructions for performing an inverse discrete Fourier transform on a plurality of input symbols for a plurality of frequency subbands to obtain a plurality of time-domain samples, wherein each frequency subband is associated with a different steering vector of a plurality of steering vectors, and

instructions for repeating a portion of the plurality of time-domain samples to obtain the input sequence of time-domain samples;

instructions for generating a plurality of output sequences of time-domain samples for a plurality of antennas by temporally modifying the input sequence of time-domain samples, wherein the computer-executable instructions for generating the plurality of output sequences of time-domain samples comprise

instructions for delaying the input sequence by different amounts to generate the plurality of output sequences, wherein each different amount is associated with a different steering vector of the plurality of steering vectors; and

instructions for transmitting the plurality of output sequences from the plurality of antennas starting at different times.

29. The computer-program apparatus of claim 28, wherein the plurality of steering vectors are defined to vary beams in a continuous manner across the plurality of frequency subbands.

30. The computer-program apparatus of claim 28, wherein the plurality of steering vectors are defined to change the different amounts in a linear manner across the plurality of frequency subbands.