Performance Evaluation and Optimization of Dual-Hop Communication over Nakagami-m Fading Channels in the Presence of Co-Channel Interferences

The performance of dual-hop communication over independent and non-identical Nakagami-m fading channels in the presence of co-channel interference is investigated. Specifically, an upper-bound of the equivalent signal-to-interference-plus-noise ratio (SINR) at the destination is introduced. Then, the cumulative distribution function (CDF) and the probability density function (PDF) of the upper bounded SINR are obtained. Moreover, simple, yet general, asymptotic expression for the error probability is presented and discussed. Besides, with the goal to minimize the asymptotic average error probability of the system under study, we investigate three optimization schemes, namely, adaptive power allocation under fixed location for the relay, optimal relay positioning with fixed power allocation, and joint optimization of the power allocation and relay location under transmit power constraint. Results show that optimum power allocation brings only coding gain, while the optimum relay location scheme yields diversity gains as well.