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
OG exemplary drawing
 
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.