Method and apparatus for pilot communication in a multi-antenna wireless communication system

• US 8,139,672 B2
• Filed: 03/27/2006
• Issued: 03/20/2012
• Est. Priority Date: 09/23/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gore, Dhananjay Ashok, Ji, Tingfang, Kadous, Tamer
• Primary Examiner(s): Joseph, Jaison
• Application Number:
  US11/390,622
• Publication Number:
  US 20070071127A1
• Time in Patent Office: 2,185 Days
• Field of Search: 375/130, 375/131, 375/132, 375/295, 375/296
• US Class Current: 375/295
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 27/2613 Structure of the reference signals

Abstract

Systems and methodologies are described that facilitate improved pilot information to MIMO user devices without increasing interference of SISO user devices in a wireless communication environment. A data communication signal can be generated and transmitted at a first power level, and a continuous pilot waveform comprising pilot information related to the data signal can be generated and sent at a second power level below the first transmission power level. Alternatively, a discontinuous pilot waveform can be generated so that it does not overlap with pilot segments in the first waveform, and can be transmitted at the first power level without interfering with the first waveform as received by a SISO user device. A MIMO user device can receive both waveforms, and can employ the pilot waveform to better estimate a MIMO channel for the first waveform.

Claims

1. A method of performing pilot communication in a wireless communication environment, comprising:

transmitting a code-division multiplexed (CDM) waveform that is continuous from at least one antenna at a base station; and

transmitting a second waveform comprising pilot information related to the CDM waveform from at least one other antenna at the base station;

wherein the second waveform comprises an OFDM waveform, and the pilot information in the second waveform temporally overlaps one of traffic channel information and control channel information in the CDM waveform.

2. The method of claim 1, the second waveform comprises pilot segments that are employed to estimate a channel for a multiple-input, multiple-output (MIMO) user device.

3. The method of claim 1, the second waveform is discontinuous and the pilot segments of the second waveform do not overlap pilot segments of the CDM waveform.

4. The method of claim 1, the second waveform is discontinuous and the pilot segments of the second waveform do not overlap pilot segments or medium access channel (MAC) segments in the CDM waveform.

5. The method of claim 1, further comprising providing the second waveform in fewer than all interlaces comprising the CDM waveform.

6. The method of claim 1, further comprising providing the second waveform according to a predetermined pattern.

7. The method of claim 6, wherein the predetermined pattern comprises transmitting the second waveform once every N transmissions of the CDM waveform, where N is an integer greater than 1.

8. The method of claim 1, further comprising transmitting the second waveform according to a pattern that is based at least in part on a data rate of the CDM waveform.

9. The method of claim 1, further comprising transmitting the second waveform according to a pattern that is based at least in part on a spectral efficiency of the CDM waveform.

10. The method of claim 1, further comprising transmitting the second waveform at a power level approximately 15 dB to 25 dB below a power level at which the CDM waveform is transmitted, wherein the second waveform is a continuous waveform.

11. The method of claim 1, further comprising transmitting the second waveform at a power level approximately 20 dB below a power level at which the first waveform is transmitted, wherein the second waveform is a continuous waveform.

12. The method of claim 1, further comprising terminating transmission of the second waveform upon switching from a low-throughput modulation format to a high-throughput modulation format for transmission of the CDM waveform.

13. The method of claim 1, further comprising terminating transmission of the second waveform upon switching from a quadrature phase shift keying (QPSK) modulation format to a 64-quadrature amplitude modulation (QAM) format for transmission of the CDM waveform.

14. The method of claim 1, wherein the first waveform comprises portions transmitted from at least two antennas at the base station during a given time period and the second waveform comprises portions transmitted from the same at least two antennas at the base station during the given time period, wherein the first waveform and second waveform are mapped to the at least two antennas according to a linear combination.

15. The method of claim 14, wherein the first waveform and the second waveform are mapped to the at least two antennas according to an orthonormal matrix.

16. The method of claim 14, wherein the first waveform and the second waveform are mapped to the at least two antennas and wherein the first waveform and second waveform are mapped to the at least two antennas according to a unitary matrix.

17. An apparatus for wireless communication with a SISO user device having a single antenna and a MIMO user device having a plurality of antennas, comprising:

a plurality of antennas, wherein one of said antennas provides all wireless signaling used by the SISO user device to recover communication information sent by said apparatus to the SISO user device; and

a processor, coupled to the plurality of antennas and configured to transmit a CDM waveform from said one antenna for the SISO user device and the MIMO user device, said CDM waveform comprising OFDM pilot segments, said processor further configured to transmit a second waveform comprising pilot information related to the CDM waveform from at least one other of said plurality of antennas for the MIMO user device.

18. The apparatus of claim 17, the processor generates the CDM waveform as a continuous waveform, comprising data segments and the OFDM pilot segments.

19. The apparatus of claim 18, the second waveform is a continuous waveform.

20. The apparatus of claim 19, the processor instructs transmission of the first waveform at a first power level and the second waveform at a second power level approximately 20 dB below the first power level.

21. The apparatus of claim 17, the first waveform is a continuous waveform, comprising data segments, OFDM pilot segments, and MAC segments.

22. The apparatus of claim 21, the second waveform is a discontinuous waveform comprising OFDM pilot segments that do not overlap with the pilot segments of the CDM waveform.

23. The apparatus of claim 17, the processor instructs transmission of the second waveform according to a predetermined pattern.

24. The apparatus of claim 17, the processor instructs transmission of the second waveform once every N transmissions of the CDM waveform, where N is an integer greater than 1.

25. A wireless communication apparatus for communication with first and second wireless communication devices, comprising:

means for generating a CDM waveform comprising OFDM pilot segments;

means for generating an OFDM pilot waveform; and

means for transmitting the CDM waveform from an antenna that provides all wireless signaling used by the first device to recover communication information sent by said wireless communication apparatus to the first device, and for transmitting the OFDM pilot waveform from at least one other antenna for reception at the second device.

26. The apparatus of claim 25, wherein the OFDM pilot waveform is discontinuous and comprises pilot segments that do not overlap with pilot segments in the CDM waveform.

27. The apparatus of claim 25, further comprising means for transmitting the CDM waveform and the OFDM pilot waveform at a substantially similar power level.

28. The apparatus of claim 25, the OFDM pilot waveform is a continuous waveform that comprises pilot segments that overlap with pilot segments in the CDM waveform.

29. The apparatus of claim 25, further comprising means for transmitting the OFDM pilot waveform at a power level approximately 15-25 dB below transmission power level of the CDM waveform.

30. The apparatus of claim 29, further comprising means for transmitting the OFDM pilot waveform at a power level approximately 20 dB below a transmission power level of the CDM waveform.

31. The apparatus of claim 25, wherein the first waveform comprises portions transmitted from at least two antennas at the base station during a given time period and the second waveform comprises portions transmitted from the same at least two antennas at the base station during the given time period, further comprising means for mapping the first waveform and second waveform according to a linear combination.

32. The apparatus of claim 31, wherein means for mapping comprises means for mapping according to an orthonormal matrix.

33. The apparatus of claim 31, wherein means for mapping comprises means for mapping according to a unitary matrix.

34. A computer-readable medium having stored thereon computer-executable instructions for supporting operations of a wireless communication apparatus that communicates with first and second wireless communication devices, said operations comprising:

generating a CDM waveform comprising OFDM pilot segments;

generating an OFDM pilot waveform comprising pilot information related to the CDM waveform; and

transmitting the CDM waveform from an antenna that provides all wireless signaling used by the first device to recover communication information sent by said wireless communication apparatus to the first device, and concurrently transmitting the OFDM waveform from at least one other antenna for reception at the second device.

35. The computer-readable medium of claim 34, the instructions further comprising generating the OFDM pilot waveform as a discontinuous waveform with pilot segments that do not overlap pilot segments in the CDM waveform.

36. The computer-readable medium of claim 35, the instructions further comprising transmitting the OFDM pilot waveform and the CDM waveform at a same power level.

37. The computer-readable medium of claim 34, the instructions further comprising generating the OFDM pilot as a continuous waveform comprising pilot segments that overlap with pilot segments in the CDM waveform.

38. The computer-readable medium of claim 37, the instructions further comprising transmitting the OFDM pilot waveform at a power level approximately 15-25 dB below a transmission power level for the CDM waveform.

39. The computer-readable medium of claim 38, the instructions further comprising transmitting the OFDM pilot waveform at a power level approximately 20 dB below a transmission power level for the CDM waveform.

40. A processor that executes instructions that support operations of a wireless communication apparatus that communicates with first and second wireless communication devices, the operations comprising:

generating a CDM waveform that has OFDM pilot segments;

generating an OFDM pilot waveform that has pilot information related to the CDM waveform; and

transmitting the CDM waveform from an antenna that provides all wireless signaling used by the first device to recover communication information sent by said wireless communication apparatus to the first device, and transmitting the OFDM pilot waveform from at least one other antenna for reception at the second device.

41. The processor of claim 40, the instructions further comprising generating the OFDM pilot waveform as a discontinuous waveform having discontinuities between pilot segments, wherein the discontinuities are generally aligned with the pilot segments in the CDM waveform.

42. The processor of claim 41, the instructions further comprising transmitting the CDM waveform and the OFDM pilot waveform at approximately the same power level.

43. The processor of claim 40, the instructions further comprising generating the OFDM pilot waveform as a continuous waveform having pilot segments that overlap the pilot segments in the CDM waveform.

44. The processor of claim 43, the instructions further comprising transmitting the OFDM pilot waveform at a power level approximately 15-25 dB below a transmission power level for the CDM waveform.

45. The processor of claim 43, the instructions further comprising transmitting the OFDM pilot waveform at a power level approximately 20 dB below a transmission power level for the CDM waveform.