Physical Layer Security for MA-Aided SISO OFDM Systems Under Eavesdropper Location Uncertainty

Abstract

This letter investigates physical layer security (PLS) in a movable-antenna (MA) aided single-input single-output (SISO) orthogonal frequency division multiplexing (OFDM) system, where the eavesdropper (Eve) is known only within a suspicious region and also optimizes its own MA positions. A closed-form artificial noise (AN) scheme based on the legitimate channel state information is proposed, which is fully eliminated at the receiver. The resulting bilevel non-convex secrecy rate maximization is solved by a cutting-set based alternating optimization framework combining gradient-assisted particle swarm optimization, projected subgradient ascent and a best-response oracle. Simulation results demonstrate significant secrecy rate gains over conventional baselines.