Relay-assisted OFDM for NLOS ultraviolet communication

Ultraviolet (UV) communication enables non-line-of-sight (NLOS) outdoor wireless connectivity and is particularly desirable to relax or eliminate pointing and tracking requirements of infrared links. The main two degrading factors in UV links are high path loss and intersymbol interference resulting from the frequency selectivity nature of the channel. In this paper, we propose the powerful combination of relay-assisted (cooperative) transmission and multicarrier architecture based on orthogonal frequency division multiplexing (OFDM) for a superior performance over UV channels. Specifically, we consider a cooperative diversity system with orthogonal cooperation protocol and use DC-biased optical OFDM as the underlying physical layer. We investigate the error rate performance of the proposed relay-assisted OFDM UV system and demonstrate significant performance gains over point-to-point OFDM UV systems.