Physical Layer Security in Heterogeneous Networks with Jammer Selection and Full-Duplex Users

In this paper, we enhance physical layer security for downlink heterogeneous networks (HetNets) by using friendly jammers and full-duplex users. The jammers are selected to transmit jamming signal if their interfering power on the scheduled users is below a threshold, meanwhile the scheduled users confound the eavesdroppers using artificial noise by full-duplexing. Using the tools of stochastic geometry, we derive the expressions of connection probability and secrecy probability. In particular, the locations of active jammers are modeled by a modified Poisson hole process (PHP). Determining the jammer selection threshold is further investigated for connection probability maximization subject to the security constraints. A greedy algorithm is proposed to efficiently solve this problem. The accuracy of the theoretical analysis and the efficiency of the proposed algorithm are evaluated by numerical simulations.