Patent ID: 7991083
Filing Date: 2011-08-02
Classification: H04B,H04J,H04L

Abstract:
1. A method for detecting a preamble in a multi-cell communication system, the method comprising: at a wireless communication device, receiving a signal transmitted over a frequency band assigned to one or more cells in the multi-cell communication system, wherein the frequency band is divided into two or more narrow band segments in each of which is transmitted a unique pseudonoise sequence from a plurality of unique pseudonoise sequences for a corresponding cell; sampling the signal in the time domain using a sampling window of predetermined size to produce a predetermined number of samples; applying a Fast Fourier Transform to the predetermined number of samples to obtain a first frequency domain vector, wherein each element of the first frequency domain vector represents one of the narrow band segments; calculating an energy associated with each narrow band segment based on the first frequency domain vector in order to identify a narrow band segment with a highest energy; generating a second frequency domain vector using elements of the first frequency domain vector associated with the narrow band segment with the highest energy; generating one or more bit masks; generating one or more third frequency domain vectors from the second frequency domain vector by applying the one or more bit masks to the second frequency domain vector; generating a correlation vector by correlating one or more of the plurality of unique pseudonoise sequences with the one or more third frequency domain vectors; comparing one or more elements in the correlation vector with a predetermined threshold to determine that the preamble is present in the signal when at least one element in the correlation vector exceeds the predetermined threshold; and detecting the preamble when it is determined to be present in the signal based on the comparing.