Pilot tone processing systems and methods

• US 8,139,544 B1
• Filed: 05/04/2005
• Issued: 03/20/2012
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: Intellectual Ventures I LLC (Intellectual Ventures LLC)
• Original Assignee: Intellectual Ventures I LLC (Intellectual Ventures LLC)
• Inventors: Webster, Mark A., Seals, Michael J.
• Primary Examiner(s): Doan, Kiet
• Application Number:
  US11/121,743
• Time in Patent Office: 2,512 Days
• Field of Search: 370/334, 370/208, 370/335, 370/203, 370/148, 370/206, 370/204, 455/502, 455/245.1, 455/101, 455/134, 455/562.1, 375/340, 375/267, 375/260, 348/731
• US Class Current: 370/334
• CPC Class Codes: H04B 7/068 using space frequency diversity space-frequency coding H04L1/0606
• CPC Class Codes: H04B 7/0684 using different training sequences per antenna
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

Embodiments of pilot tone processing systems and methods are disclosed. In one embodiment, among others, a pilot tone processing system comprises pilot tone logic configured to receive first pilot tone data corresponding to a first transmit antenna and second pilot tone data corresponding to a second transmit antenna and separate the first pilot tone data from the second pilot tone data.

Claims

1. A method comprising:

receiving, at a receiving device, a first signal transmitted, from a first antenna, on a first communications path and a second signal transmitted, from a second antenna, on a second communications path, wherein the first signal includes a first set of data subcarriers and a first set of pilot subcarriers, and wherein the second signal includes a second set of data subcarriers and a second set of pilot subcarriers;

separating the first set of data subcarriers from the second set of data subcarriers and separating the first set of pilot subcarriers from the second set of pilot subcarriers according to a signal separating function, wherein the signal separating function is based on a first channel estimate for the first communications path and a second channel estimate for the second communications path; and

match-filter combining at least one pilot subcarrier of the first set of pilot subcarriers with at least one pilot subcarrier of the second set of pilot subcarriers.

2. The method of claim 1, wherein the channel estimate for the first communications path is based on a first preamble of the first signal, and wherein the channel estimate for the second communications path is based on a second preamble of the second signal.

3. The method of claim 1, further comprising separating the first set of data subcarriers from the first set of pilot subcarriers, and separating the second set of data subcarriers from the second set of pilot subcarriers.

4. The method of claim 1, wherein the signal separating function comprises a zero forcing function.

5. The method of claim 1, wherein the signal separating function comprises a minimum mean squared error function.

6. The method of claim 1, further comprising correcting phase and jitter distortions in the first and second sets of data subcarriers based on the first and second sets of pilot subcarriers.

7. The method of claim 1, further comprising combining each individual pilot subcarrier from the first set of pilot subcarriers with a corresponding individual pilot subcarrier from the second set of pilot subcarriers to create a set of combined pilot subcarriers, and phase-lock looping each combined pilot subcarrier of the set of combined pilot subcarriers.

8. The method of claim 7, wherein combining comprises maximum ratio combining or simple combining.

9. The method of claim 1, wherein the first signal is received by a first receiver device and the second signal is received by a second receiver device.

10. The method of claim 9, wherein the first signal and the second signal are transmitted by a single transmitter.

11. The method of claim 1, further comprising:

generating a channel matrix for the first signal; and

computing a matrix inverse of the channel matrix, wherein the first channel estimate is based at least in part on the matrix inverse.

12. The method of claim 11, wherein the channel matrix is based at least in part on an amplitude of the first signal.

13. The method of claim 11, wherein the channel matrix is based at least in part on a phase of the first signal.

14. The method of claim 1, wherein the first set of data subcarriers are at a first set of corresponding frequencies and the first set of pilot subcarriers are at a second set of corresponding frequencies, and wherein the second set of data subcarriers are at the first set of corresponding frequencies and the second set of pilot subcarriers are at the second set of corresponding frequencies.

15. A system comprising:

a receiver device configured to;

receive a first signal transmitted on a first communications, from a first antenna, path and a second signal transmitted, from a second antenna, on a second communications path, wherein the first signal includes a first set of data subcarriers and a first set of pilot subcarriers, and wherein the second signal includes a second set of data subcarriers and a second set of pilot subcarriers;

separate the first set of data subcarriers from the second set of data subcarriers and separate the first set of pilot subcarriers from the second set of pilot subcarriers according to a signal separating function, wherein the signal separating function is based on a first channel estimate for the first communications path and a second channel estimate for the second communications path; and

match-filter combine at least one pilot subcarrier from the first set of pilot subcarriers with at least one pilot subcarrier of the second set of pilot subcarriers.

16. The system of claim 15, wherein the signal separating function comprises at least one of a zero forcing function or a minimum mean squared error function.

17. The system of claim 15, wherein the receiver device is configured to separate the first set of data subcarriers from the first set of pilot subcarriers, and to separate the second set of data subcarriers from the second set of pilot subcarriers.

18. The system of claim 15, wherein the receiver device is further configured to correct phase and jitter distortions in the first and second sets of data subcarriers based on the first and second sets of pilot subcarriers.

19. The system of claim 15, wherein the receiver device is further configured to combine each individual pilot subcarrier from the first set of pilot subcarriers with a corresponding individual pilot subcarrier from the second set of pilot subcarriers to create a set of combined pilot subcarriers, and wherein the receiver device is configured to phase-lock loop each combined pilot subcarrier of the set of combined pilot subcarriers.

20. The system of claim 19, wherein the receiver device is configured to combine individual pilot subcarriers of the first and second sets of pilot subcarriers according to a maximum ratio combine function or a simple combine function.

21. The system of claim 15, wherein the functionality performed by the receiver device is implemented in hardware, software, or a combination of hardware and software.

22. The system of claim 15, wherein the functionality of the receiver device is implemented in digital circuitry, analog circuitry, or a combination of digital and analog circuitry.

23. The system of claim 15, wherein the channel estimate for the first communications path is based on a first preamble of the first signal, and wherein the channel estimate for the second communications path is based on a second preamble of the second signal.

24. A system comprising:

means for receiving a plurality of signals, wherein the plurality of signals comprise a first signal transmitted on a first communications path from a first antenna to the means for receiving and a second signal transmitted on a second communications path from a second antenna to the receiving means, wherein the first signal includes a first set of data subcarriers at and a first set of pilot subcarriers, and wherein the second signal includes a second set of data subcarriers and a second set of pilot subcarriers;

means for separating the first set of data subcarriers from the second set of data subcarriers and for separating the first set of pilot subcarriers from the second set of pilot subcarriers according to a signal separating function, wherein the signal separating function is based on a first channel estimate for the first communications and a second channel estimate for the second communications path; and

means for match-filter combining at least one pilot subcarrier of the first set of pilot subcarriers with at least one pilot subcarrier of the second set of pilot subcarriers.

25. A non-transitory computer-readable medium having instructions stored thereon, the instructions comprising:

instructions for receiving a first signal transmitted, from a first antenna, on a first communications path and a second signal transmitted, from a second antenna, on a second communications path, wherein the first signal includes a first set of data subcarriers and a first set of pilot subcarriers, and wherein the second signal includes a second set of data subcarriers and a second set of pilot subcarriers;

instructions for separating the first set of data subcarriers from the second set of data subcarriers and separating the first set of pilot subcarriers from the second set of pilot subcarriers according to a signal separating function, wherein the signal separating function is based on a first channel estimate for the first communications path and a second channel estimate for the second communications path; and

instructions for match-filter combining at least one pilot subcarrier of the first set of pilot subcarriers with at least one pilot subcarrier of the second set of pilot subcarriers.

26. The non-transitory computer-readable medium of claim 25, further comprising:

instructions for separating the first set of data subcarriers from the first set of pilot subcarriers; and

instructions for separating the second set of data subcarriers from the second set of pilot subcarriers.

27. The non-transitory computer-readable medium of claim 25, further comprising:

instructions for generating a channel matrix for the first signal, wherein the channel matrix is based at least in part on an amplitude and a phase of the first signal; and

instructions for computing a matrix inverse of the channel matrix, wherein the first channel estimate is based at least in part on the matrix inverse.

28. The non-transitory computer-readable medium of claim 25, further comprising:

instructions for combining each individual pilot subcarrier from the first set of pilot subcarriers with a corresponding individual pilot subcarrier from the second set of pilot subcarriers to create a set of combined pilot subcarriers; and

instructions for phase-lock looping each combined pilot subcarrier of the set of combined pilot subcarriers.

29. The non-transitory computer-readable medium of claim 25, further comprising instructions for correcting phase and jitter distortions in the first and second sets of data subcarriers based on the first and second sets of pilot subcarriers.