Radio resource allocation for physical-layer security in D2D underlay communications

Device-to-Device (D2D) communications have been proposed recently to improve the spectral efficiency. In this paper, we consider physical-layer security in D2D communication as an underlay to cellular networks with an eavesdropper. Benefiting from the underlaid spectrum reuse, D2D users can contribute to the system secrecy capacity, while D2D users may interfere the cellular users and decrease their secrecy capacity. We formulate this problem as a matching problem in the weighted bipartite graph and introduce the Kuhn-Munkres (KM) algorithm to provide the optimal solution. Simulation results show that the system secrecy capacity can be greatly improved by introducing D2D communications underlaying cellular networks.