Two-way relay protocol for optical wireless scattering communication

This letter addresses the half-duplex bidirectional relay protocol design and optimization for outdoor optical wireless scattering communication system. Such a relay system consists of two user nodes and one relay node. The relay node broadcasts to the user nodes using a predetermined power based on the number of photoelectrons received from the user nodes. Each user node can estimate the signal from the other node according to the combination of its own symbol and the broadcast signal from the relay. We consider two types of protocols based on the hard-decision and soft-forwarding at the relay node, named the hard-decision relaying protocol and the soft-forwarding relaying protocol, respectively. Simulation results show that the soft-forwarding relaying protocol can reach smaller bit error rate compared with the hard-decision relaying protocol. © 1997-2012 IEEE.