Performance Evaluation and Optimization of Traffic-Aware Cellular Multiuser Two-Way Relay Networks Over Nakagami-m Fading

We consider a cellular multiuser two-way relay network, where a multiantenna base station communicates with one of the several single-antenna mobile stations via a single-antenna relay terminal. We derive the exact and asymptotic overall outage probability (OOP) expressions of the considered system with asymmetric traffic under Nakagami-
m
fading. Based on the asymptotic analysis, we formulate three optimization problems, namely, optimal power allocation (OPA) with fixed relay location, optimal relay location with fixed power allocation, and jointly OPA and relay location to minimize the OOP. Specifically, we investigate two OPA schemes, called OPA I and OPA II. To this end, OPA I provides the solutions for individual transmit powers at each terminal, whereas under OPA II, relay terminal is assigned with half of the total power and the remaining power is allocated to the end terminals. The numerical and simulation results corroborate our theoretical findings, and reveal that under highly asymmetric traffic, OPA I can achieve a significant OOP performance than OPA II for different relay locations, except at the relay location where both coincide. Under symmetric traffic, OPA I outperforms OPA II, irrespective of relay locations. The OOP performance can be further improved if the power allocation and relay location are jointly optimized, especially under unbalanced conditions.