Closed Form Expressions for Underwater‐RF System Over Decode‐Forward Relaying

In the development of advanced communication systems for the underwater‐radio frequency (RF), use of relay has been found highly significant. Due to multipath fading and shadowing, performance of any wireless communication is severely degraded. Using relay‐based communication system deployed in the severe fading environment, we can achieve significant improvement in the performance. Although there is need of extra radio resources for deployment of relay, efficiency of network and availability of service can be greatly enhanced even in deep fading environments. This paper has covered assessment of performance of relaying system using decode‐and‐forward (DaF) relaying scheme under asymmetric fading scenario. For sending the signal from source to relay (S‐R), k ‐ µ fading channel for underwater medium was used and for communication from relay towards destination in RF link, Rayleigh fading channel was taken into consideration. More specifically, for the proposed system, closed form expression of the outage probability has been obtained. Derived closed form expression of the outage probability has been further used for getting the unified closed form expression of the bit error rate (BER) for various types of modulation techniques, such as binary phase shift keying (BPSK), differential phase shift keying (DPSK), and binary frequency shift keying (BFSK) modulation techniques. We have also examined how various fading parameters and signal‐to‐noise ratio (SNR) will affect the outage probability and BER in the latter part of this paper.