Multi-Array Beamforming and Mode Optimization for Cooperative Multi-Cell ISAC Systems

In this letter, we investigate cooperative multi-cell integrated sensing and communications (ISAC) systems with multi-array base stations (BSs). First, we explore the relations among channels of co-located or distributed arrays and develop a cooperative multi-cell multi-array sensing model to jointly handle the received echoes of targets by multiple arrays and different BSs. Then, we formulate a joint array mode selection and beamforming problem for the multi-cell ISAC system, aiming to maximize the minimum multi-cell sensing signal-to-clutter-plus-interference-and-noise ratio of targets, subject to the signal-to-interference-plus-noise ratio requirements of communication users. To solve this problem, a joint multi-BS multi-array beamforming and mode optimization scheme is proposed, where the beamforming is optimized with a developed alternating transmit and receive beamforming algorithm and the mode optimization is optimized with the coordinate descent method. Simulation results demonstrate that deploying multi-array BSs in multi-cell ISAC systems significantly enhances system performance and improves signal coverage.