OFDM/OFDMA timing synchronization using non-consecutive pilot subcarrier assignment
View Patent ↗Systems and methods which are adapted determine timing with respect to an orthogonal frequency division (OFD) channel, such as may be used with respect to an OFDM or OFDMA systems through reliably identifying timing of a first arriving signal path. Embodiments use deconvolution to construct the channel impulse response associated with a received signal. The first arriving path for the received signal may readily and reliably be determined using the channel impulse response information.
1. A method comprising:
constructing channel impulse response information with respect to a received signal using a deconvolution of a partial channel estimation and channel subcarrier information associated with said received signal, wherein said channel subcarrier information includes information with respect to a plurality of orthogonal frequency division subcarriers carrying said received signal, and wherein said constructing channel impulse response information comprises iteratively analyzing said partial channel estimation and stopping the iteratively analyzing if either a number of iterations exceeds a predetermined value or a maximum peak magnitude within a current iteration of said partial channel estimation falls below a predetermined value; and
determining a timing offset with respect to said received signal using said channel response information.
2. The method of claim 1 , wherein said plurality of orthogonal frequency division subcarriers are not consecutive and non-uniformly distributed orthogonal frequency division subcarriers of an orthogonal frequency division bandwidth.
3. The method of claim 2 , wherein said plurality of orthogonal frequency division subcarriers comprise a ranging channel.
4. The method of claim 2 , wherein said plurality of orthogonal frequency division subcarriers comprise a pilot channel.
5. The method of claim 2 , wherein said plurality of orthogonal frequency division subcarrier positions are known at both a transmitting station and a receiving station prior to transmission of said received signal.
6. The method of claim 1 , wherein said iteratively analyzing said partial channel estimation comprises:
calculating said partial channel estimation for subsequent iterations, wherein said subsequent iterations have a pilot signal peak detected in a previous iteration masked.
7. The method of claim 1 , wherein said iteratively analyzing said partial channel estimation comprises:
identifying a peak magnitude and position within a plurality of iterations of said partial channel estimation.
8. The method of claim 1 , wherein said determining a timing offset comprises:
identifying a first arriving path of said received signal using said channel impulse response information.
9. The method of claim 8 , wherein said identifying a first arriving path comprises:
calculating a moving average from said channel impulse response information.
10. The method of claim 9 , wherein said identifying a first arriving path comprises:
identifying a first falling edge within said moving average, said first arriving path being the path associated with a position of said first falling edge.
11. The method of claim 1 , further comprising:
implementing said timing offset for subsequent communications.
12. The method of claim 11 , further comprising:
utilizing a second plurality of orthogonal frequency division subcarriers for said subsequent communications.
13. A method comprising:
constructing channel impulse response information with respect to a received signal, said received signal having been received using a plurality of orthogonal frequency division subcarriers; and
identifying a first arriving path of said received signal using said channel impulse response information by calculating a moving average from said channel impulse response information wherein said identifying a first arriving path comprises identifying a first falling edge within said moving average, said first arriving path being the path associated with a position of said first falling edge.
14. The method of claim 13 , further comprising:
implementing a timing offset associated with said first arriving path for subsequent communications.
15. The method of claim 14 , further comprising:
utilizing a second plurality of orthogonal frequency division subcarriers for said subsequent communications.
16. The method of claim 13 , wherein said plurality of orthogonal frequency division subcarriers are not consecutive and non-uniformly distributed orthogonal frequency division subcarriers of an orthogonal frequency division bandwidth.
17. The method of claim 16 , wherein said plurality of orthogonal frequency division subcarriers comprise a ranging channel.
18. The method of claim 13 , wherein said constructing channel impulse response information comprises:
using a deconvolution of a partial channel estimation and channel subcarrier information associated with said received signal.
19. The method of claim 18 , wherein said constructing channel impulse response information comprises:
iteratively analyzing said partial channel estimation.
20. The method of claim 19 , wherein said iteratively analyzing said partial channel estimation comprises:
calculating said partial channel estimation for iterations having a previously detected pilot signal peak masked.
21. The method of claim 19 , wherein said iteratively analyzing said partial channel estimation comprises:
stopping the iteratively analyzing if either a number of iterations exceeds a predetermined value or a maximum peak magnitude within a current iteration of said partial channel estimation falls below a predetermined value.
22. The method of claim 13 , wherein said constructing channel impulse response information comprises:
identifying a plurality of peak magnitudes and positions within said partial channel estimation.
23. A method comprising:
constructing channel impulse response information with respect to a received signal, said received signal having been received using a plurality of orthogonal frequency division subcarriers, wherein said constructing channel impulse response information comprises using a deconvolution of a partial channel estimation and channel subcarrier information associated with said received signal, and iteratively analyzing said partial channel estimation wherein said iteratively analyzing comprises calculating said partial channel estimation for iterations having a previously detected pilot signal peak masked; and
identifying a first arriving path of said received signal using said channel impulse response information by calculating a moving average from said channel impulse response information.
24. The method of claim 23 wherein said identifying a first arriving path comprises identifying a first falling edge within said moving average, said first arriving path being the path associated with a position of said first falling edge.
25. The method of claim 24 , further comprising:
implementing a timing offset associated with said first arriving path for subsequent communications.
26. The method of claim 25 , further comprising:
utilizing a second plurality of orthogonal frequency division subcarriers for said subsequent communications.
27. The method of claim 23 , wherein said plurality of orthogonal frequency division subcarriers are not consecutive and non-uniformly distributed orthogonal frequency division subcarriers of an orthogonal frequency division bandwidth.
28. The method of claim 27 , wherein said plurality of orthogonal frequency division subcarriers comprise a ranging channel.
29. The method of claim 23 , wherein said constructing channel impulse response information comprises:
identifying a plurality of peak magnitudes and positions within said partial channel estimation.
30. A method comprising:
constructing channel impulse response information with respect to a received signal, said received signal having been received using a plurality of orthogonal frequency division subcarriers, wherein said constructing channel impulse response information comprises identifying a plurality of peak magnitudes and positions within said partial channel estimation; and
identifying a first arriving path of said received signal using said channel impulse response information by calculating a moving average from said channel impulse response information.