Outage Constrained Robust Secure Beamforming in Integrated Sensing and Communication Systems

In this letter, we consider the secure multi-user downlink communication scheme against eavesdroppers in Integrated Sensing and Communication (ISAC) systems, where the ISAC base station (BS) transmits ISAC waveform to serve communication users and sense targets, and artificial noise (AN) is employed to guarantee the transmission secrecy. In particular, we study the robust ISAC beamforming design under the assumption of imperfect legitimate users’ and eavesdroppers’ channel state information (CSI). Specifically, we aim to minimize the squared error between designed and desired beampatterns under the probabilistic outage constraints concerning the secrecy performance as well as power budget constraint. To deal with the non-convex problem, we utilize the semidefinite relaxation (SDR) technique and Bernstein-type inequality to convert the problem to a tractable form. Numerical results show that the proposed robust beamforming design algorithm is able to approach the performance under perfect CSI, and illustrates the trade-off between sensing and secrecy performances.