A novel receiver for Filp-OFDM in optical wireless communication

A unipolar orthogonal frequency division multi-plexing (OFDM) technique called flipped OFDM (Flip-OFDM), is suitable for intensity modulation and direct detection (IM/DD) channel which needs the transmitted signal to be real and positive. Flip-OFDM uses two consecutive OFDM subframes to transmit the positive and negative parts of the signal, respectively. In the conventional receiver, only the difference of the two subframes is used to recover the signal, leading to the under-utilization of the received power. This paper proposes a novel receiver characterizing temporal and spectral diversity combining to improve the performance of Flip-OFDM by extracting effective information from both the sum and the difference of the two subframes. Simulations show that the novel receiver provides a significant gain of about 2.3 dB at the BER of 10-4, compared with the conventional one in additive white gaussian noise (AWGN) channel. Moreover, the proposed receiver also simplifies computational complexity compared with the existing iterative receiver.