Patent ID: 8831150

Claim:
A method for detecting presence of a preamble in a received signal, the received signal having one or more frequency-multiplexed component signals received over a frequency range, the frequency range being subdivided into a random access channel and a non-random access channel, the received signal further having temporal reference locations such that boundaries of transmitted symbols in the one or more component signals received over the non-random access channel are approximately time-aligned to the temporal reference locations, the method comprising: filtering the received signal so as to obtain a filtered signal comprising a substantial portion of the one or more component signals received over the random access channel without including a substantial portion of the one or more component signals received over the non-random access channel; correlating the filtered signal with a predetermined preamble to generate a plurality of correlation outputs for detecting presence of the preamble in the filtered signal; and pre-processing the received signal before the received signal is filtered, or post-processing the filtered signal after the filtered signal is obtained and before the filtered signal is correlated, or performing both the pre-processing of the received signal and the post-processing of the filtered signal, wherein the pre-processing of the received signal includes modifying the received signal by multiplying the received signal with a first time-domain window function configured to substantially smooth discontinuities present in the received signal at the temporal reference locations, and wherein the post-processing of the filtered signal includes modifying the filtered signal by multiplying the filtered signal with a second time-domain window function configured to substantially suppress spikes present in the filtered signal in the neighborhood of the temporal reference locations.