Frequency-Domain Diversity Combining Receiver for ACO-OFDM System

This paper proposes a new receiver based on frequency-domain diversity combining (FDDC) for an asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) system. Compared with its time-domain diversity combining (TDDC) counterpart, the FDDC receiver is capable of more effectively exploiting the frequency selectivity of the channel to further improve the detection performance, which is proved by postcombining signal-to-noise-ratio (SNR) analysis. An enhanced version of the FDDC receiver, which is called eFDDC, is also proposed subsequently. It allows for optimal selection among multiple sets of candidate symbol vectors based on signum matrix estimation. Simulation results show that the proposed FDDC and eFDDC receivers outperform the TDDC receiver. With a sufficient number of candidate symbol vector sets, the eFDDC receiver even outperforms a kind of iterative receiver, which is known to have superior performance in current literature, yet the complexity of eFDDC is lower due to the avoidance of matrix inversion. Those facts suggest that the FDDC and eFDDC receivers are strong receiver candidates for the ACO-OFDM system.