Optimum receivers for non-linearly distorted OFDM signals

We derive the structure of the optimum receiver for non-linearly distorted orthogonal frequency division multiplexed (OFDM) signals. This receiver consists of a set of correlators or a set of filters matched to every possible frequency component in the non-linearly distorted OFDM signal followed by either a maximum a posteriori (MAP) or a maximum likelihood (ML) detector. We use the iterative estimation algorithm proposed by H. Nishijima et al. (see Proc. IEEE Int. Symp. on Personal, Indoor and Mobile Radio Commun., vol.1, p.45-8, 1996; Okada, M. et al., IEEE Int. Symp. on Personal, Indoor and Mobile Radio Commun., vol.3, p.1100-4, 1997; IEICE Trans. Commun., vol.E81-B, p.737-44, 1998) to alleviate the complexity associated with ML detection. Simulation results demonstrate that the optimum receiver outperforms both the conventional OFDM receiver and the sub-optimum OFDM receiver proposed by Nishijima et al. This optimum OFDM receiver structure is particularly useful for application to the uplink of fiber-radio based wireless networks because it allows the linearity requirements of optical components to be relaxed.