Hybrid Optical/RF Channel Performance Analysis for Turbo Codes

Turbo coded data transmission over a hybrid channel, consisting of parallel free space optical (FSO) and radio frequency (RF) links, is considered, and analytical bit error performance results are derived. The FSO link is modeled using the gamma-gamma distribution function, and both random and block fading channels are used. Random and specific codeword bit selections for transmission through the RF link are considered. Conditions to guarantee bit error rate (BER) performance improvement in hybrid channels over FSO only links are derived. In the case of block fading channels, the hybrid channel using turbo codes is found to provide several dBs of gain in the signal-to-noise ratio (SNR) over an optical only link. A technique to jointly optimize puncturing and RF bit selection patterns for the hybrid channel is also presented. Results demonstrate significant BER performance improvement obtained from the proposed joint optimization approach.