Patent ID: 7738575
Filing Date: 2010-06-15
Classification: H04B,H04L

Abstract:
1. A method for compensating for excess DC offset in samples of an orthogonal frequency division multiplexed (OFDM) symbol before providing the samples for transformation from time domain to frequency domain at a receiver in a communication system, the OFDM symbol including a first group of samples having a FFT number of samples, followed by a second group of samples having a null number of samples, followed by a third group of samples having a guard number of samples, the null number not exceeding the FFT number, the method comprising: selecting an add number of samples received by the receiver from a beginning of the second group immediately following the first group to obtain a null overlap group, the add number not exceeding the null number; obtaining an average DC offset for each sample of the null overlap group; selecting the add number of samples from a beginning of the first group to obtain a Fourier overlap group; overlapping the Fourier overlap group over the null overlap group to obtain pairs of overlapping samples; adding together members of each of the pairs of overlapping samples to obtain samples of an overlapped-and-added group, the overlapped-and-added group immediately following the first group, and each sample of the overlapped-and-added group corresponding to one sample of the null overlap group and having a corresponding average DC offset of the one sample of the null overlap group; subtracting the corresponding average DC offset either from each sample of the null overlap group or from each sample of the overlapped-and-added group; and providing the FFT number of samples beginning after the Fourier overlap group and ending after the overlapped-and-added group for the transformation, wherein the second group forms a null post-fix for the OFDM symbol.