Cooperative communication design of physical layer security enhancement with social ties in random networks

Social relationships among wireless nodes play a key role of wireless networks to establish trusted services applications. Owing to inherent randomness of wireless environment, the security and confidentiality of wireless information transmission urgently needs to be addressed. Physical layer security (PLS) technique has been proposed as an effective solution of securing wireless communications, by exploiting channel characteristics. Different from most previous works that ignored relationship among wireless nodes, this paper studies secrecy performance of cooperative communication based random network with social friendships, and presents four types of cooperative relaying and jamming schemes. In particular, proposed schemes introduce the concept of Local Friendship Circle (LFC) and Long-range Friendship Annulus (LFA), in which the optimal relay and friendly jammers are selected based on their physical locations and channel state information (CSI). In the context of PLS, the connection outage probability (COP) and secrecy outage probability (SOP) are introduced to evaluate performance of designed strategies, and their mathematical expressions are derived with the tools of stochastic geometry. Numerical simulations validate the theoretical analysis and illustrate the influence of system configurations on reliability and security performances.