Patent ID: 8064546

Claim:
A method of preamble detection in a random access channel of a wireless transmission system comprising the steps of: receiving a transmitted signal; converting the received signal into frequency-domain samples via a discrete Fourier transform; demodulating a group of said frequency-domain samples to produce samples of the received signal; converting said samples of demodulated signal into time-domain samples using an inverse fast Fourier transform; modifying the time-domain samples to produce modified time-domain samples; summing a group of modified time-time domain samples to produce a sum signal; comparing the sum signal against a pre-computed preamble detection threshold calculated as follows T det = T r AN nca · γ n where: T det and T r /AN nca are the respective absolute and relative preamble detection thresholds; A is the number of receive antennas: N nca is the number of non-coherent accumulations; and γ n is the noise floor estimate; and detecting a preamble in the random access channel if the sum signal exceeds the pre-computed preamble detection threshold.