MIMO PREAMBLE FOR INITIAL ACCESS WITH AN UNKNOWN NUMBER OF TRANSMIT ANTENNAS

• US 20100067599A1
• Filed: 09/17/2008
• Published: 03/18/2010
• Est. Priority Date: 09/17/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Naguib, Ayman Fawzy, Dayal, Pranav
• Granted Patent: US 9,252,862 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0667 of delayed versions of same signal using space-time coding H04L1/0618
• CPC Class Codes: H04L 27/261 Details of reference signals

Abstract

For certain embodiments, a preamble sequence associated with a particular number of transmit antennas may allow a receiving mobile station to determine the number of transmit antennas used for transmission. The preamble sequence may be selected from one of a set of Constant Amplitude and Zero Auto Correlation (CAZAC) sequences corresponding to all of the supported number of transmit antennas. As a result, a receiving station may be able to determine the sequence sent by correlation and, thereby determine the number of antennas used for transmission. Given the number of transmit antennas, the mobile station may then perform MIMO channel estimation during initial synchronization to recover the channel taps between each transmit and each receive antenna.

Claims

1. A method for wireless communications in a multiple input multiple output (MIMO) communications system, comprising:

decoding a preamble sequence based on symbols received from one or more receive antennas; and

determining, based on the decoded preamble sequence, a number of transmit antennas.

2. The method of claim 1, wherein determining, based on the decoded preamble sequence, a number of transmit antennas comprises:

determining the number of transmit antennas used to transmit the preamble sequence.

3. The method of claim 1, wherein decoding the preamble sequence comprises:

correlating received demodulated preamble sequences with a plurality of known preamble sequences corresponding to different numbers of transmit antennas.

4. The method of claim 3, wherein:

the preamble sequence is transmitted with a Constant Amplitude and Zero Auto Correlation (CAZAC) sequence; and

correlating received demodulated preamble sequences with a plurality of known preamble sequences comprises correlating the received demodulated preamble sequences with a plurality of known CAZAC sequences corresponding to different numbers of transmit antennas.

5. The method of claim 4, wherein the preamble sequence is transmitted from a plurality of transmit antennas using a Cyclic Delay Diversity (CDD) transmission scheme.

6. The method of claim 1, further comprising performing channel estimation for a plurality of pairs of the receive and transmit antennas.

7. A method for wireless communications in a multiple input multiple output (MIMO) communications system, comprising:

determining a number of transmit antennas to use for a transmission;

selecting, from a plurality of preamble sequences corresponding to different numbers of transmit antennas, a preamble sequence corresponding to the determined number of transmit antennas; and

transmitting the selected preamble sequence from the determined number of transmit antennas.

8. The method of claim 7, wherein the selected preamble sequence is a Constant Amplitude and Zero Auto Correlation (CAZAC) sequence, selected from a plurality of CAZAC sequences corresponding to different numbers of transmit antennas.

9. The method of claim 8, wherein transmitting the selected preamble sequence from the determined number of transmit antennas comprises transmitting the preamble sequence from a plurality of transmit antennas using a Cyclic Delay Diversity (CDD) transmission scheme.

10. A device for wireless communications in a multiple input multiple output (MIMO) communications system, comprising:

logic for decoding a preamble sequence based on symbols received from one or more receive antennas; and

logic for determining, based on the decoded preamble sequence, a number of transmit antennas.

11. The device of claim 10, wherein the logic for determining the number of transmit antennas is configured to determine the number of transmit antennas used to transmit the preamble sequence.

12. The device of claim 10, wherein the logic for decoding the preamble sequence is configured to:

correlate received demodulated preamble sequences with a plurality of known preamble sequences corresponding to different numbers of transmit antennas.

13. The device of claim 12, wherein:

the preamble sequence is transmitted with a Constant Amplitude and Zero Auto Correlation (CAZAC) sequence; and

the logic for decoding the preamble sequence is configured to correlate received demodulated preamble sequences with a plurality of known preamble sequences comprises correlating the received demodulated preamble sequences with a plurality of known CAZAC sequences corresponding to different numbers of transmit antennas.

14. The device of claim 13, wherein the preamble sequence is transmitted from a plurality of transmit antennas using a Cyclic Delay Diversity (CDD) transmission scheme.

15. The device of claim 10, further comprising logic for performing channel estimation for a plurality of pairs of the receive and transmit antennas.

16. A device for wireless communications in a multiple input multiple output (MIMO) communications system, comprising:

logic for determining a number of transmit antennas to use for a transmission;

logic for selecting, from a plurality of preamble sequences corresponding to different numbers of transmit antennas, a preamble sequence corresponding to the determined number of transmit antennas; and

logic for transmitting the selected preamble sequence from the determined number of transmit antennas.

17. The device of claim 16, wherein the selected preamble sequence is a Constant Amplitude and Zero Auto Correlation (CAZAC) sequence, selected from a plurality of CAZAC sequences corresponding to different numbers of transmit antennas.

18. The device of claim 17, wherein the logic for transmitting the selected preamble sequence from the determined number of transmit antennas is configured to transmit the preamble sequence from a plurality of transmit antennas using a Cyclic Delay Diversity (CDD) transmission scheme.

19. An apparatus for wireless communications in a multiple input multiple output (MIMO) communications system, comprising:

means for decoding a preamble sequence based on symbols received from one or more receive antennas; and

means for determining, based on the decoded preamble sequence, a number of transmit antennas.

20. The apparatus of claim 19, wherein the means for determining the number of transmit antennas is configured to determine the number of transmit antennas used to transmit the preamble sequence.

21. The apparatus of claim 19, wherein the means for decoding the preamble sequence is configured to:

correlate received demodulated preamble sequences with a plurality of known preamble sequences corresponding to different numbers of transmit antennas.

22. The apparatus of claim 21, wherein:

the preamble sequence is transmitted with a Constant Amplitude and Zero Auto Correlation (CAZAC) sequence; and

the means for decoding the preamble sequence is configured to correlate received demodulated preamble sequences with a plurality of known preamble sequences comprises correlating the received demodulated preamble sequences with a plurality of known CAZAC sequences corresponding to different numbers of transmit antennas.

23. The apparatus of claim 22, wherein the preamble sequence is transmitted from a plurality of transmit antennas using a Cyclic Delay Diversity (CDD) transmission scheme.

24. The apparatus of claim 19, further comprising means for performing channel estimation for a plurality of pairs of the receive and transmit antennas.

25. An apparatus for wireless communications in a multiple input multiple output (MIMO) communications system, comprising:

means for determining a number of transmit antennas to use for a transmission;

means for selecting, from a plurality of preamble sequences corresponding to different numbers of transmit antennas, a preamble sequence corresponding to the determined number of transmit antennas; and

means for transmitting the selected preamble sequence from the determined number of transmit antennas.

26. The apparatus of claim 25, wherein the selected preamble sequence is a Constant Amplitude and Zero Auto Correlation (CAZAC) sequence, selected from a plurality of CAZAC sequences corresponding to different numbers of transmit antennas.

27. The apparatus of claim 26, wherein the means for transmitting the selected preamble sequence from the determined number of transmit antennas is configured to transmit the preamble sequence from a plurality of transmit antennas using a Cyclic Delay Diversity (CDD) transmission scheme.

28. A computer-program product for wireless communications in a multiple input multiple output (MIMO) communications system, comprising:

instructions for decoding a preamble sequence based on symbols received from one or more receive antennas; and

instructions for determining, based on the decoded preamble sequence, a number of transmit antennas.

29. The computer-program product of claim 28, wherein the instructions for determining, based on the decoded preamble sequence, a number of transmit antennas comprise:

instructions for determining the number of transmit antennas used to transmit the preamble sequence.

30. The computer-program product of claim 28, wherein the instructions for decoding the preamble sequence comprise:

instructions for correlating received demodulated preamble sequences with a plurality of known preamble sequences corresponding to different numbers of transmit antennas.

31. The computer-program product of claim 30, wherein:

the preamble sequence is transmitted with a Constant Amplitude and Zero Auto Correlation (CAZAC) sequence; and

the instructions for correlating received demodulated preamble sequences with a plurality of known preamble sequences comprise instructions for correlating the received demodulated preamble sequences with a plurality of known CAZAC sequences corresponding to different numbers of transmit antennas.

32. The computer-program product of claim 31, wherein the preamble sequence is transmitted from a plurality of transmit antennas using a Cyclic Delay Diversity (CDD) transmission scheme.

33. The computer-program product of claim 28, further comprising instructions for performing channel estimation for a plurality of pairs of the receive and transmit antennas.

34. A computer-program product for wireless communications in a multiple input multiple output (MIMO) communications system, comprising:

instructions for determining a number of transmit antennas to use for a transmission;

instructions for selecting, from a plurality of preamble sequences corresponding to different numbers of transmit antennas, a preamble sequence corresponding to the determined number of transmit antennas; and

instructions for transmitting the selected preamble sequence from the determined number of transmit antennas.

35. The computer-program product of claim 34, wherein the selected preamble sequence is a Constant Amplitude and Zero Auto Correlation (CAZAC) sequence, selected from a plurality of CAZAC sequences corresponding to different numbers of transmit antennas.

36. The computer-program product of claim 35, wherein the instructions for transmitting the selected preamble sequence from the determined number of transmit antennas comprise instructions for transmitting the preamble sequence from a plurality of transmit antennas using a Cyclic Delay Diversity (CDD) transmission scheme.