Movable Antenna-Enabled Secure Communications Against Simultaneous Jamming and Eavesdropping Attacks

This paper focuses on a movable antenna (MA) enabled downlink multi-user communication system, where a base station (BS) aims to transmit messages to multiple users with a malicious jammer and multiple eavesdroppers posing threats. Both the BS and the users feature MAs, while the jammer and eavesdroppers make use of fixed-position antennas (FPAs). In accordance with the BS’s transmission power budget, designated MA moving regions, and minimum spacing between transmitting MAs, the system’s minimum secrecy rate is maximized through the joint design of transmit beamforming and both transmitting and receiving MA locations. To solve the non-trivial problem, a block coordinate descent (BCD) algorithm employing successive convex approximation (SCA) is implemented by iteratively designing the transmit beamforming, the specific transmitting MA position, and the receiving MA positions. Herein, auxiliary variables, first- and/or second-order Taylor expansions, and approximate construction methods for non-convex terms are introduced to handle each subproblem. Numerical results indicate that repositioning the transmitting MAs is more effective in combating eavesdropping attacks, while relocating the receiving MAs is more beneficial for countering jamming attacks. In comparison to traditional FPA schemes, the proposed scheme attains a notably greater system’s minimum secrecy rate.