Optimal relay selection based on social threshold for D2D communications underlay cellular networks

With the ever increasing number of user terminals and fast-growing demands for local service, D2D (Device-to-Device) relay communication technology is becoming essential to the next generation mobile networks, where an efficient relay selection scheme not only improves the system performance but also conserves energy consumption. Aiming at encouraging relay node to voluntarily forward data and regarding with relay node selection issue, this paper proposes an improved social-aware relay selection strategy. In particular, we introduce the concept of social threshold which is based on the knowledge of social relationship among mobile users. Then by exploiting optimal stopping theory, we further propose an optimal relay selection strategy on the basis of social threshold method. Simulation results indicate that the proposed algorithm is effective in reducing the number of probing times of candidate relays and improving the throughput gain of the system, which strikes a balance between energy consumption and system utility.