Patent ID: 7844007

Claim:
A signal processor for determining a maximum Carrier to Interference plus Noise Ratio (CINR) and associated index frequency offset (IFO) and preamble index, the signal processor accepting a preamble, the signal processor having: a candidate generator accepting said preamble and generating candidates, said candidate generator having: a preamble memory for storing said preambles; a first iteration variable coupled to an ideal preamble generator and providing an associated ideal preamble; a second iteration variable coupled to an integer frequency offset which offsets the contents of said preamble memory by a value determined by said second iteration variable; a decimator coupled to the output of said integer frequency offset and providing every m th sample as an output, where m is a reuse number; a multiplier which forms said candidate by multiplying each subcarrier of the output of said decimator with each subcarrier of said ideal preamble generator; a candidate evaluator accepting a plurality of candidates and selecting one with a maximum carrier to interference and noise ratio (CINR), said candidate evaluator having: a data substitution which accepts said candidate and generates a Yk value with one subcarrier value set to the average value of adjacent subcarriers; a first power calculator which computes the power of each subcarrier of Yk, sums the subcarrier powers of Yk, thereby generating a first value; a first drop edge function which forms an output from Yk by dropping subcarriers at edges; a smoothing filter accepting said Yk and convolving Yk with Wk, where Wk is a discrete Fourier transform of a window function, Yk convolved with Wk being applied to a second drop edge function which forms an output by dropping subcarriers at edges; a summer which forms an output by subtracting said second drop edge function output from said first drop edge function output; a second power calculator determining the power in each subcarrier of said summer output and summing them to form a second value; a signal and interference calculator which accepts said first value and said second value, to form a signal value and an interference value; a carrier to interference plus noise ratio (CINR) calculator for computing a CINR value accompanied by said first iteration variable and said second iteration variable; a maximum finder for storing said CINR value, said associated first iteration variable value, and said associated second iteration variable value if a current said CINR value is greater than a previous said CINR value.