Stochastic Geometry Analysis of Achievable Transmission Capacity for Relay-assisted Device-to-Device Networks

Relay-assisted Device-to-Device (D2D) communication is an enhanced technology for D2D communication. With relay nodes' assistances, the communication distance of the D2D pair is extended and the quality of communication can be improved. This paper focuses on the achievable transmission capacity of relay-assisted D2D network while keeping a low outage probability of the cellular users. based on stochastic geometry, the mathematical model of relay-assisted D2D network, with relay selection criterion, is formed and analyzed. Subsequently, the optimal transmission power ratio of the cellular system to the D2D system and the optimal relay selection range are derived. Furthermore, the achievable transmission capacity with derived optimal parameters is presented as a close-form expression. Then the numerical results show that the performance of the D2D network can be improved by relay-assisted transmission in case of poor wireless environment. In addition, the influences of the densities of both cellular, D2D and relay users and the communication distances between D2D pairs are evaluated in this paper.