Cooperative Relaying and Jamming Design for Secure LPWAN Wireless Communication

Physical layer security methods based on joint relay and jammer selection（JRJS） have been widely investigated in the study of secure wireless communications. Different from current works on JRJS schemes, which assumed that the global channel state information（CSI） of the eavesdroppers（Eves）was known beforehand, then the optimal relaying and jamming relays were determined. More importantly,the time complexity of selecting optimal jamming relay is O（N2）, where N is the maximum number of relays/Eves. In this paper, for the scenario where the source wants to exchange the message with the destination, via relaying scheme due to longer communication distance and limited transmission power, in the presence of multiple Eves, with the assumption of Eves' perfect CSI and average CSI, we propose two kinds of JRJS methods. In particular, the time complexity of finding the optimal jammer can be reduced to O（N）. Furthermore, we present a novel JRJS scheme for no CSI of Eves by minimizing the difference between expected signal and interfering signal at the destination. Finally, simulations show that the designed methods are more effective than JRJS and other existing strategies in terms of security performance.