Location-Aided Secure Transmission for Uplink Massive MIMO System Against Full-Duplex Jammer

In the study of physical layer security for massive multiple-input multiple-output (MIMO) systems, the operating mechanism of jammer is often considered simple and fixed, which underestimates the disruption and flexibility of jamming attacks. It is possible for a massive MIMO system to suffer from simultaneous jamming and eavesdropping during the training and transmission phase, or an intelligent jammer may switch the duplex mode so as to match the purpose with lower power consumption. In these cases, the anti-jamming schemes proposed in previous papers may fail, and a robust secure transmission against flexible jamming should be designed. To this end, we mainly focus on the interactions between the base station and jammer in the uplink massive MIMO system, where the jammer is capable of working in full-duplex mode to obstruct the base station and eavesdrop on uplink users simultaneously. The spatial orthogonality brought by the location of jammer and users is used to produce a two-layer combiner at the base station for the purpose of suppressing signals from jamming direction. Under this condition, we prove that the jammer falls into a half-duplex eavesdropper. Then a statistical eavesdropping bound is given without the instantaneous channel state information (CSI) of eavesdropping channels, which guides the power control of users in order that the secrecy capacity is optimized.