Performance analysis of zero-forcing-based multiple-input multiple-output two-way relaying in overlay device-to-device communications

In this study, the authors conduct the performance evaluation and resource allocation for two-way multiple-input multiple-output-based device-to-device (D2D) communications overlaying a cellular network. The considered system model comprises of a base station, a mobile user, and a pair of D2D users, where each of them is equipped with multiple antennas and employs transmit/receive zero forcing. Based on overlaying approach, both D2D and cellular communications take place bidirectionally by employing analogue network coding with a best selected D2D user as two-way relay for the cellular links. The authors analyse the outage performance of cellular and D2D systems in a Rayleigh fading environment. They also deduce asymptotic outage behaviour of cellular system and highlight the achievable diversity order. In addition, they derive the expressions of ergodic sum rate for both the systems. Above all, they provide a selection algorithm for the best relaying D2D user and describe feasible range of power splitting factor to maximise the data rate of cellular system for a given data rate of D2D system. Numerical and simulation results validate the authors’ theoretical findings and illustrate the performance gains of the considered scheme under various antenna configurations.