Methods and arrangements for phase tracking for multi-mode operation in wireless networks

• US 9,008,167 B2
• Filed: 12/29/2012
• Issued: 04/14/2015
• Est. Priority Date: 12/29/2012
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Azizi, Shahrnaz, Perahia, Eldad, Kenney, Thomas J.
• Primary Examiner(s): Malek, Leila
• Application Number:
  US13/730,996
• Publication Number:
  US 20140185662A1
• Time in Patent Office: 836 Days
• Field of Search: 375/260, 375/232, 375/326, 375/346, 375/331, 375/340, 375/284, 375/324, 370/206, 370/208
• US Class Current: 375/232
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/03006 Arrangements for removing intersymbol interference
• CPC Class Codes: H04L 27/18 Phase-modulated carrier systems, i.e. using phase-shift keying H04L27/32 takes precedence
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2666 Acquisition of further OFDM parameters, e.g. bandwidth, subcarrier spacing, or guard interval length
• CPC Class Codes: H04L 27/2675 Pilot or known symbols

Abstract

Logic may comprise a single phase tracking implementation for all bandwidths of operation and the logic may adaptively change pre-defined and stored track parameters if the receiving packet is 1 MHz bandwidth. Logic may detect a packet and long training fields before performing a 1 MHz classification. Logic may auto-detect 1 MHz bandwidth transmissions by a property of the long training field sequences. Logic may auto-detect 1 MHz bandwidth transmissions by detecting a Binary Phase Shift Keying (BPSK) modulated first signal field symbol rather than the Quadrature Binary Phase Shift Keying (QBPSK) associated with the 2 MHz or greater bandwidth transmissions. Logic may perform an algorithm to determine an estimated phase correction value for a given orthogonal frequency division multiplexing symbol and several embodiments integrate this value with an intercept multiplier that may be 0.2 for 1 MHz transmissions and, e.g., 0.5 for 2 MHz or greater bandwidth communication.

Claims

1. A method to multi-mode phase track with shifting pilot tones, the method comprising:

receiving an orthogonal frequency division multiplexing (OFDM) transmission of a packet with pilot tones shifting locations between OFDM symbols;

processing a preamble of the packet to determine whether the OFDM transmission comprises a one megahertz bandwidth or comprises a bandwidth of two megahertz or greater;

setting a track intercept multiplier value to 0.2 if the OFDM transmission comprises a one megahertz bandwidth;

determining phase rotations of the pilot tones based upon the track intercept multiplier value; and

performing phase tracking based upon the phase rotations.

2. The method of claim 1, further comprising processing a long training field in the preamble to determine initial weight coefficients for equalization.

3. The method of claim 1, further comprising:

determining channel estimates for the pilot tones based upon the pilot tones; and

updating weight coefficients for equalization based upon the channel estimates.

4. The method of claim 1, wherein receiving the OFDM transmission comprises receiving the OFDM transmission with pilot tones shifting every N OFDM symbols, wherein N is a positive, non-zero integer.

5. The method of claim 1, wherein receiving the OFDM transmission comprises receiving the OFDM transmission with pilot tones shifting every OFDM symbol.

6. The method of claim 1, wherein determining phase rotations of the pilot tones based upon the track intercept multiplier value comprises determining the phase rotations of the pilot tones based upon a track intercept multiplier value 0.5 if the OFDM transmission comprises the bandwidth of two megahertz or greater.

7. The method of claim 1, wherein determining phase rotations of the pilot tones based upon the track intercept multiplier value comprises integrating previous phase rotations plus a current phase estimate multiplied by the track intercept multiplier value.

8. The method of claim 7, wherein integrating previous phase rotations plus a current phase estimate multiplied by the track intercept multiplier value comprises determining the current phase estimate by performing a least squares or phase averaging algorithm on the pilot tones.

9. A device to multi-mode phase track with shifting pilot tones, the device comprising:

memory to store an intercept multiplier value; and

module coupled with the memory to receive an orthogonal frequency division multiplexing (OFDM) transmission of a packet with pilot tones shifting locations between OFDM symbols;

process a preamble of the packet to determine whether the OFDM transmission comprises a one megahertz bandwidth or comprises a bandwidth of two megahertz or greater;

set a track intercept multiplier value to 0.2 if the OFDM transmission comprises a one megahertz bandwidth;

determine phase rotations of the pilot tones based upon the track intercept multiplier value; and

perform phase tracking based upon the phase rotations.

10. The device of claim 9, wherein the module comprises logic to process a long training field in the preamble to determine initial weight coefficients for equalization.

11. The device of claim 9, wherein the module comprises logic to determine channel estimates for the pilot tones based upon the pilot tones;

and update weight coefficients for equalization based upon the channel estimates.

12. The device of claim 9, wherein the module comprises logic to receive the OFDM transmission with pilot tones shifting every N OFDM symbols, wherein N is a positive, non-zero integer.

13. The device of claim 9, wherein the module comprises logic to receive the OFDM transmission with pilot tones shifting every OFDM symbol.

14. The device of claim 9, wherein the module comprises logic to determine the phase rotations of the pilot tones based upon a track intercept multiplier value 0.5 if the OFDM transmission comprises the bandwidth of two megahertz or greater.

15. The device of claim 9, wherein the module comprises logic to integrate previous phase rotations plus a current phase estimate multiplied by the track intercept multiplier value.

16. The device of claim 15, wherein the module comprises logic to determine the current phase estimate by performing a least squares or phase averaging algorithm on the pilot tones.

17. A system to multi-mode phase track with shifting pilot tones, the system comprising:

a processor, a radio, and one or more antennas coupled with the radio;

memory coupled with the processor to store an intercept multiplier value; and

a receiver coupled with the memory to receive an orthogonal frequency division multiplexing (OFDM) transmission of a packet with pilot tones shifting locations between OFDM symbols;

process a preamble of the packet to determine whether the OFDM transmission comprises a one megahertz bandwidth or comprises a bandwidth of two megahertz or greater;

set a track intercept multiplier value to 0.2 if the OFDM transmission comprises a one megahertz bandwidth;

determine phase rotations of the pilot tones based upon the track intercept multiplier value; and

perform phase tracking based upon the phase rotations; and

a transmitter coupled with the radio to transmit a second OFDM transmission with pilot tones shifting locations.

18. The system of claim 17, wherein the receiver comprises logic to process a long training field in the preamble to determine initial weight coefficients for equalization.

19. The system of claim 17, wherein the receiver comprises logic to determine channel estimates for the pilot tones based upon the pilot tones;

and update weight coefficients for equalization based upon the channel estimates.

20. The system of claim 17, wherein the receiver comprises logic to receive the OFDM transmission with pilot tones shifting every N OFDM symbols, wherein N is a positive, non-zero integer.

21. The system of claim 17, wherein the receiver comprises logic to receive the OFDM transmission with pilot tones shifting every OFDM symbol.

22. The system of claim 17, wherein the receiver comprises logic to determine the phase rotations of the pilot tones based upon a track intercept multiplier value 0.5 if the OFDM transmission comprises the bandwidth of two megahertz or greater.

23. The system of claim 17, wherein the receiver comprises logic to integrate previous phase rotations plus a current phase estimate multiplied by the track intercept multiplier value.

24. The system of claim 23, wherein the receiver comprises logic to determine the current phase estimate by performing a least squares or phase averaging algorithm on the pilot tones.

25. A machine-accessible product comprising:

a non-transitory medium containing instructions to multi-mode phase track with shifting pilot tones, wherein the instructions, when executed by a station, causes the station to perform operations, the operations comprising;

receiving an orthogonal frequency division multiplexing (OFDM) transmission of a packet with pilot tones shifting locations between OFDM symbols;

processing a preamble of the packet to determine whether the OFDM transmission comprises a one megahertz bandwidth or comprises a bandwidth of two megahertz or greater;

setting a track intercept multiplier value to 0.2 if the OFDM transmission comprises a one megahertz bandwidth;

determining phase rotations of the pilot tones based upon the track intercept multiplier value; and

performing phase tracking based upon the phase rotations.

26. The machine accessible product of claim 25, wherein the operations further comprise processing a long training field in the preamble to determine initial weight coefficients for equalization.

27. The machine accessible product of claim 25, wherein the operations further comprise:

determining channel estimates for the pilot tones based upon the pilot tones; and

updating weight coefficients for equalization based upon the channel estimates.

28. The machine accessible product of claim 27, wherein determining phase rotations of the pilot tones based upon the track intercept multiplier value comprises determining the phase rotations of the pilot tones based upon a track intercept multiplier value 0.5 if the OFDM transmission comprises the bandwidth of two megahertz or greater.

29. The machine accessible product of claim 25, wherein determining phase rotations of the pilot tones based upon the track intercept multiplier value comprises integrating previous phase rotations plus a current phase estimate multiplied by the track intercept multiplier value.

30. The machine accessible product of claim 25, wherein integrating previous phase rotations plus a current phase estimate multiplied by the track intercept multiplier value comprises determining the current phase estimate by performing a least squares or phase averaging algorithm on the pilot tones.