Method and apparatus for clock correction in MIMO OFDM

1. A method of phase correction at a wireless device comprising:

estimating a phase slope for an OFDM symbol in a data portion of a packet;

measuring a residual phase slope for the OFDM symbol in the data portion of the packet, the residual phase slope being based on a measurement of a phase slope between tracking pilots contained in the packet; and

adjusting a phase correction based upon the phase slope and the residual phase slope.

2. The method of claim 1 , adjusting further comprising:

adjusting based upon a moving average of the phase slope.

3. The method of claim 1 , estimating further comprising:

measuring an elapsed time from a start time for the packet.

4. The method of claim 1 , estimating further comprising:

comparing an estimate of a received pilot symbol with a known transmitted pilot symbol.

5. The method of claim 4 , further comprising:

estimating unknown data symbols;

obtaining an estimated phase adjustment from the estimated data symbols; and

applying the estimated phase adjustment before adjusting the phase correction.

6. The method of claim 1 , measuring further comprising:

removing an average pilot phase from received pilot symbols;

forming conjugates of received pilot symbols;

combining the conjugates with the received pilot symbols;

weighting the combined conjugates and received pilot symbols;

computing angle information; and wherein adjusting further comprises:

correcting packets received during a burst including the received pilot symbols using the angle information.

7. The method of claim 1 , measuring further comprising:

removing an average phase from received data symbols;

forming conjugates of received data symbols;

combining the conjugates with the received data symbols;

weighting the combined conjugates and received data symbols;

computing angle information; and wherein adjusting further comprises:

correcting packets received during a burst including the received data symbols using the angle information.

8. An electronic device configured to perform the method of claim 1 .

9. A non-transitory computer-readable medium comprising instructions which, when executed by a computer cause the computer to perform operations, the instructions including:

instructions for estimating a phase slope for an OFDM symbol in a data portion of a packet based on an elapsed time from the start of the packet;

instructions for measuring a residual phase slope from tracking pilots for the OFDM symbol in the data portion of the packet, the residual phase slope being based on a measurement of a phase slope between tracking pilots contained in the packet; and

instructions for adjusting a phase correction based upon the phase slope and the residual phase slope.

10. Apparatus for performing phase correction at a wireless device comprising:

means for receiving tracking pilots for an OFDM symbol;

means for estimating a phase slope for the OFDM symbol in a data portion of a packet based on an elapsed time from the start of the packet;

means for measuring a residual phase slope from tracking pilots for the OFDM symbol in the data portion of the packet, the residual phase slope being based on a measurement of a phase slope between tracking pilots contained in the packet; and

means for adjusting a phase correction based upon the phase slope and the residual phase slope.

11. The apparatus of claim 10 , the means for adjusting further comprising:

means for adjusting based upon a moving average of the phase slope.

12. The apparatus of claim 10 , the means for estimating further comprising:

means for measuring an elapsed time from a start time for the packet.

13. The apparatus of claim 10 , the means for estimating further comprising:

means for comparing an estimate of a received pilot symbol with a known transmitted pilot symbol.

14. The apparatus of claim 13 , the means for measuring a residual phase slope further comprising:

means for estimating unknown data symbols;

means for obtaining an estimated phase adjustment from the estimated data symbols; and

means for applying the estimated phase adjustment before adjusting the phase correction.

15. The apparatus of claim 10 , the means for measuring further comprising:

means for removing an average pilot phase from received pilot symbols;

means for forming conjugates of received pilot symbols;

means for combining the conjugates with the received pilot symbols;

means for weighting the combined conjugates and received pilot symbols;

means for computing angle information; and wherein adjusting further comprises:

means for correcting packets received during a burst including the received pilot symbols using the angle information.

16. The apparatus of claim 10 , the means for measuring further comprising:

means for removing an average phase from received data symbols;

means for forming conjugates of received data symbols;

means for combining the conjugates with the received data symbols;

means for weighting the combined conjugates and received data symbols;

means for computing angle information; and wherein adjusting further comprises:

means for correcting packets received during a burst including the received data symbols using the angle information.

17. Apparatus for performing phase correction at a wireless device comprising:

at least one processor configured to adjust a phase correction for received signals, the at least one processor configured to adjust the phase correction based upon a phase slope and a residual phase slope by, wherein the at least one processor is configured to estimate the phase slope for an OFDM symbol in a data portion of a packet based on an elapsed time from the start of the packet and measure a residual phase slope from tracking pilots for the OFDM symbol in the data portion of the packet, the residual phase slope being based on a measurement of a phase slope between tracking pilots contained in the packet; and

a memory coupled to the at least one processor.

18. The apparatus of claim 17 , wherein the at least one processor is configured to adjust based upon a moving average of the phase slope.

19. The apparatus of claim 17 , wherein the at least one processor is configured to comparing an estimate of a received pilot symbol with a known transmitted pilot symbol.