Performance analysis of relay-aided millimeter-wave communications with optimal and suboptimal combining at destination

Abstract

We analyze the performance of a relay network in millimeter-wave (mmWave) band, in two cases when the optimal, Maximal-Ratio Combining (MRC), or a suboptimal, Selection Combining (SC), receiver is employed at destination. The recently proposed Fluctuating Two-Ray (FTR) channel model is applied to model communication in mmWave band. Unlike existing works on the topic which restrict their analysis to channels with integer-valued Nakagami-m fading figures, we extend the analysis to more practical cases, where the fading figure may take arbitrary real values greater than 0.5. We also derive equations which enables us to relate the FTR channel parameters to the underlying network parameters, namely distances between the nodes, and path loss exponents. We analyze the system in both cases where a line-of-sight link between the transmitting and receiving nodes is either present or absent. Distribution of the Signal-to-Noise Ratio (SNR) at combiner’s output, as well as system outage probability and spectral efficiency are analytically derived. Throughout extensive simulations, we study and compare the performance of MRC and SC receivers for different system setups. We also consider the effect of applying antenna arrays with different antenna patterns, as well as the effect of interference from other nodes, on the system performance. The results suggest that despite its simple and low-complexity structure, in most cases, SC receiver demonstrates an encouraging performance and shows small performance losses compared to the optimal MRC receiver.