In communication systems, efficient use of the spectrum is an indispensable concern. Recently the use of\r\ncompressed sensing for the purpose of estimating orthogonal frequency division multiplexing (OFDM) sparse\r\nmultipath channels has been proposed to decrease the transmitted overhead in form of the pilot subcarriers which\r\nare essential for channel estimation. In this article, we investigate the problem of deterministic pilot allocation in\r\nOFDM systems. The method is based on minimizing the coherence of the submatrix of the unitary discrete fourier\r\ntransform (DFT) matrix associated with the pilot subcarriers. Unlike the usual case of equidistant pilot subcarriers,\r\nwe show that non-uniform patterns based on cyclic difference sets are optimal. In cases where there are no\r\ndifference sets, we perform a greedy method for finding a suboptimal solution. We also investigate the\r\nperformance of the recovery methods such as orthogonal matching pursuit (OMP) and iterative method with\r\nadaptive thresholding (IMAT) for estimation of the channel taps.
Loading....