Stable and Proportional Fair User Pairing Algorithm for D2D-Relay Systems

Device-to-device (D2D) communication is one of the key technologies for the collaborative heterogeneous networks towards the fifth generation (5G) ecosystem. Among D2D techniques, D2D-relay, which combines the advantages of both D2D and relay technology, is a promising tool to enhance performance of communication systems. In this paper, we propose a stable and proportional fair user pairing algorithm for D2D-relay systems. The proposed algorithm adopts the concept in symmetric pairing theory, which is verified to be absolutely stable. Moreover, we also proved that the proposed algorithm is Pareto optimal in system performance. Numerical results demonstrate that the proposed algorithm distinctly outperforms the traditional user pairing methods in both energy efficiency (EE) and proportional fairness (PF) aspects, while maintaining a comparable throughput performance with traditional pairing methods, which is attractive for practical applications.