Multihop full duplex relaying with coherent signaling: Outage probability analysis and power optimization

Abstract

This paper considers coherent relaying with interference subtraction (CRIS) for exploiting the direct links in multi-hop decode-and-forward full duplex relay (MHDF-FDR) networks. Initially, we derive new approximate closed form expression for the end-to-end outage probability of MHDF-FDR networks that use CRIS (i.e., MHDF-CRIS-FDR networks), taking into account the residual self-interference (RSI) generated by full duplex operation at the relay nodes and by considering the links in the network to suffer from independent, non-identical Nakagami fading. We provide an upper bound for the outage probability as well and further present an asymptotic expression by considering Rayleigh fading channels. Secondly, optimal power allocation (OPA) is considered for MHDF-CRIS-FDR networks that either maximizes the end-to-end instantaneous rate or minimizes the end-to-end outage probability, with constraints on the maximum power for the transmitting nodes. We observe that both these problems are non-convex. Sequential convex programming (SCP) based iterative algorithms are then proposed to determine the OPA vectors corresponding to the above optimization problems. The convergence of the algorithms are also established. The benefits of OPA are reported in terms of improvements in outage and rate performance of the network. We also make extensive comparison of the outage performance of MHDF-CRIS-FDR scheme against two conventional FDR schemes. The analytical results are corroborated by conducting Monte-Carlo simulations.