| US 7,587,016 B2 | ||
| MIMO timing recovery | ||
| Rohit V. Gaikwad, San Diego, Calif. (US); and Rajendra Tushar Moorti, Mountain View, Calif. (US) | ||
| Assigned to Broadcom Corporation, Irvine, Calif. (US) | ||
| Filed on Apr. 12, 2006, as Appl. No. 11/402,572. | ||
| Claims priority of provisional application 60/700968, filed on Jul. 20, 2005. | ||
| Claims priority of provisional application 60/700967, filed on Jul. 20, 2005. | ||
| Prior Publication US 2007/0019750 A1, Jan. 25, 2007 | ||
| Int. Cl. H04L 7/00 (2006.01); H04L 27/00 (2006.01); H04L 27/06 (2006.01) | ||
| U.S. Cl. 375—355 [375/326; 375/343] | 25 Claims |

| 1. An apparatus, comprising:
a first symbol timing recovery module that is operable to:
calculate a modified correlation function that varies as a function of each sample of a first plurality of samples of a first
moving window and each sample of a second plurality of samples of a second moving window of an OFDM (Orthogonal Frequency
Division Multiplexing) packet, wherein the modified correlation function is normalized with respect to a first power corresponding
to the first moving window and a second power corresponding to the second moving window;
compare the modified correlation function to a symbol timing recovery threshold;
identify a peak value of the modified correlation function when the modified correlation function exceeds the symbol timing
recovery threshold and when the modified correlation function is substantially non-increasing;
identify a mid-point of a decreasing region of the modified correlation function that, when biased by a predetermined amount,
is less than the peak value of the modified correlation function;
identify an end-point of the decreasing region of the modified correlation function that, when scaled by a predetermined scaling
factor, is less than the peak value of the modified correlation function;
compare the first power corresponding to the first plurality of samples of the first moving window to a first power threshold;
and
compare the second power corresponding to the second plurality of samples of the second moving window to a second power threshold;
and
a choice logic module that is operable to:
receive a first symbol timing recovery signal, corresponding to a first stream of a plurality of receive streams, from the
first symbol timing recovery module;
receive a second symbol timing recovery signal, corresponding to a second stream of the plurality of receive streams, from
a second symbol timing recovery module that is also implemented within the apparatus;
receive a first carrier detect signal, corresponding to the first stream of the plurality of receive streams, from a first
carrier detect module that is also implemented within the apparatus;
receive a second carrier detect signal, corresponding to a second stream of the plurality of receive streams, from a second
carrier detect module that is also implemented within the apparatus; and
based on the first carrier detect signal and the second carrier detect signal, select either the first symbol timing recovery
signal, the second symbol timing recovery signal, or a non-symbol timing recovery signal for each of the first stream and
the second stream of the plurality of receive streams.
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