Diversity combining for asymmetrically clipped optical OFDM in IM/DD channels

Abstract

This paper looks at the problem of performance enhancement for Orthogonal Frequency-Division Multiplexing (OFDM) transmission in intensity modulated, direct detected (IM/DD) optical systems. Due to the unipolarity of the IM/DD channel, asymmetric clipping and associated biasing is inevitable, which results in a significant signal degradation. ACO-OFDM [1] has been previously proposed to avoid this detrimental distortion with the cost of a lower spectral efficiency. In this paper, with the help of a detailed analysis of such distortion, a simple combining algorithm is proposed. This algorithm extracts the instructive information inside the clipping distortion, and requires no changes to the e..