Patent ID: 8300674
Filing Date: 2012-10-30
Classification: H04B,H04L

Abstract:
1. A method of operating a wireless receiver, the method comprising: using a base sequence to generate a set of plural sequences formed by delay-Doppler shifts of the base sequence, the plural sequences of the set each corresponding to differing signatures for respective differing transmitters, the base sequence comprising a frequency hopping pattern having frequency hopping segments; using a selected sequence of the set of sequences to be a candidate sequence; using the base signal and a received signal to form a delay-Doppler image with respect to an image area pertinent to the candidate sequence; wherein forming the delay-Doppler image comprises acts (1)-(6): (1) using a discrete Fourier Transform (DFT) to form a two dimensional array of DFT window segments for a given Doppler offset (δ (2) determining at least a portion of the delay-Doppler image for the given delay offset by summing elements in the array for the given delay offset which match the frequency hopping pattern; (3) deriving a two dimensional array of DFT window segments for a next delay offset from the array of DFT window segments of a previous delay offset; (4) determining at least a portion of the delay-Doppler image for the current given delay offset by summing elements in the array for the current delay offset which match the frequency hopping pattern; (5) repeating acts (3) and (4) for successive next delay offsets until portions of the delay-Doppler image have been determined for all delay offsets for a given Doppler offset; (6) repeating acts (1) through (5) for successive next Doppler offsets until portions of the delay-Doppler image have been determined for all delay-Doppler offsets; determining, for each of plural candidate delay-Doppler indices a detection metric with respect to the portion of the delay-Doppler image for the corresponding candidate delay-Doppler index, each candidate delay-Doppler index corresponding to a portion of the delay-Doppler image; and determining which candidate delay-Doppler index has a best detection metric and determining a candidate sequence corresponding to the candidate delay-Doppler index having the best detection metric to be the signature sequence.