Patent ID: 7366089

Claim:
An apparatus for combining of M high data rate wideband packetized OFDM wireless communication signals (“M signals”) to form a combined output signal, wherein at least M receive antennas each receive one of the M signals, wherein each of the M signals includes N frequency bins, and wherein M is an integer greater than or equal to 2 and N is a positive integer, the apparatus comprising: a joint timing recovery unit that performs joint coarse signal timing estimation and joint frequency offset estimation on digital data corresponding to each of the M signals; M Fast Fourier Transform (FFT) units that each convert the digital data for one of the M signals into frequency domain information in the form of sub-carrier data for each of N frequency bins for that one M signal and that output the frequency domain information for each of the M signals; and a combiner that weights and combines the frequency domain information of the M FFT units to thereby generate the combined output signal having reduced circuit impairments and channel effects, wherein the joint timing recovery unit that performs joint timing estimation determines a coarse end time for P consecutive Shorts within the M signals, wherein the joint timing recovery unit determines the coarse end time using self correlation of some of the P Shorts within the M signals, wherein the joint timing recovery unit includes a joint coarse signal time estimation unit that performs the joint coarse signal timing estimation on each of the M signals, the joint coarse signal time estimation unit comprising: M self-correlation units, wherein each self-correlation unit independently self-correlates the some of the P Shorts in one of the M signals after the automatic gain control unit indicates the start of the M signals and outputs for the one M signal a self correlation signal that is the self-correlation of the P Shorts, wherein P is a positive integer; M weighting units that weight the self correlation outputs based on the signal strength; a summer that sums the M weighted self correlation signals to obtain a weighted summed self correlation signal; a normalizing unit that normalizes the weighted summed self correlation signal, thereby outputting a normalized self correlation signal; and a coarse timing estimation unit that receives the normalized self correlation signal and obtains, for the M signals, the end time for the P Shorts in the M signals by comparing the normalized self correlation signal power to a threshold.