Receiver Design for Asymmetrically Clipped Optical OFDM

Asymmetrically clipped optical OFDM (ACO-OFDM) is compatible with optical intensity modulation and is well suited to bandlimited optical wireless channels. By carefully locating data on odd subcarriers and clipping the resulting time signal, ACO-OFDM guarantees non-negative output amplitudes and clipping noise orthogonal to the information. However, in the conventional receiver, clipping noise is ignored in detection and data are extracted from odd sub carriers only. In this paper, a new receiver design for ACO-OFDM is proposed which exploits the structure of the clipping noise to improve the optical power efficiency. By observing the anti-symmetry of time domain samples, a simple pairwise maximum likelihood detector is developed and is used to fix half of the received samples to zero. Simulation results show that employing the proposed detector design leads to 1.3 dB optical gain at a BER of 10-5.