Performance of Regular Low Density Parity Check Codes Over Hybrid Optical/RF Channels

A hybrid channel, consisting of a Free Space Optical (FSO) link and a parallel Radio Frequency (RF) link, is considered. Information bits are first encoded by a Low Density Parity Check (LDPC) code and the coded bits are transmitted through both the FSO and the RF links. A Density Evolution (DE) technique to analyze the convergence of the message passing algorithm at the detector is described for the hybrid channel, and a Gaussian Approximation (GA) technique is presented. Numerical results showing the benefits of the hybrid channel are discussed.