Fast GAMP Algorithm for Nonlinearly Distorted OFDM Signals

In this letter, the design of a low-complexity receiver which is robust to orthogonal frequency division multiplex (OFDM) signals with nonlinear clipping distortion is investigated. An approximation of the probability density function (PDF) of the received signals with nonlinear distortion is derived. Based on iteration-dependent approximation of the mean and variance of the clipped signal, a fast generalized approximate message passing (F-GAMP) algorithm is proposed. The proposed F-GAMP achieves bit error rate (BER) performance gain over the conventional OFDM receiver due to the F-GAMP's ability to recover inter-carrier interference (ICI) and exploit frequency diversity induced by the spectral growth of a clipped signal. With almost the same BER performance as the conventional GAMP algorithm, the proposed F-GAMP reduces the computational complexity by a factor of about 3000!