Interference Constrained D2D Communication with Relay Underlaying Cellular Networks

This paper proposes the problem that the direct communication between two D2D UEs is impossible since the outage probability of D2D communication goes beyond the threshold defined by system. The problem is solved by applying relay to Device-to-Device (D2D) communication, which is defined as D2D communication with relay mode. In this communication mode, relay is selected from idle Cellular User Equipments (CeUEs), and both of two hops in it are D2D communication. In this paper, we provide the criteria of employing this communication mode. First we derive out the interference constrained precondition for applying the mode of D2D communication with relay based on outage probabilities analysis, and then the criterion of employing D2D communication with relay mode is proposed by comparing the sum-capacity of this mode with that of cellular communication mode on the basis of the optimal relay selection. By simulating, we compare the occurrence probabilities of the modes of D2D communication, cellular communication and D2D communication with relay. The numerical results also reveal the D2D communication with relay mode can improve the average sum-capacity in contrast with cellular communication mode based on the proposed criteria.