Optimisation of secrecy rate in cooperative device to device communications underlaying cellular networks

摘要

In this study, the optimisation of cooperation level and uplink spectrum sharing are analysed by employing physical layer security concept in the device to device communications underlaying cellular networks. It is assumed that two transmitting devices communicate with the same receiving device in the presence of a passive eavesdropper. Also, it is assumed that one of the two transmitting devices aids the other one as a relay node. The optimum cooperation level and channel assignment schemes are obtained through maximizing the secrecy rate under constraints of satisfying the quality of services for cellular users (CUs) and the receiving device. In this sense, the selected CU which shares its resource block acts as a friendly jammer to interfere the eavesdropper. Although the proposed approach initially leads to a non-convex optimization problem, it can be solved efficiently by using GloptiPloy (global optimum polynomial) and SeDuMi software packages. Simulation results are provided to evaluate the performance of the proposed optimum cooperation level scheme and demonstrate the superiority of the proposed approach compared to the conventional fixed cooperation level schemes.