Multi-hop relaying systems in the presence of co-channel interference over Nakagami-m fading channels

Performance analysis of multi-hop wireless networks with non-regenerative relays over Nakagami-m fading channels in the presence of co-channel interference is presented in this paper. In the analysis, an arbitrary number of independent and identically distributed Nakagami-m interferers will be considered. Closed-form expression for the cumulative distribution function (CDF) of the upper bounded end-to-end signal-to-interference-plus-noise ratio (SINR) at the destination is given. The obtained CDF is then considered to study the average bit error probability (ABEP). Furthermore, an approximate expression for the CDF of the instantaneous end-to-end SINR is derived, based on which simple and general asymptotic expression for the error probability is presented and discussed. The derived asymptotic equation is shown to reduce to the already published equation in Rayleigh fading, which corroborate the exactness of the derived analysis. Besides, analytical comparison between amplify-and-forward and decode-and-forward multi-hop systems in terms of ABEP is provided. Optimisation of the power allocation at the network´s transmit nodes and the positioning of the relays are studied as well. It is shown that optimum power allocation achieves only coding gain, whereas optimising relay locations yields diversity gains as well as coding gain.