Energy-Efficient Interference Cancellation for Coordinated Multi-Point ISAC Systems

Integrated sensing and communication (ISAC) systems leverage coordinated multi-point (CoMP) base stations (BSs) to deliver high-accuracy sensing and robust connectivity. However, the integration of sensing and communication in CoMP-ISAC systems faces significant challenges from interference within and among BSs, which adversely affects performance and increases energy consumption, thereby limiting commercial adoption. This paper proposes a CoMP-ISAC system design aimed at enabling energy-efficient interference cancellation through the collaborative optimization of BS mode selection and transceiver design among distributed BSs, while satisfying constraints related to communication quality of service (QoS), sensing output signal-to-clutter-plus-noise ratio (SCNR), and total transmit power budget. The BS mode selection involves identifying the sensing receiver by selecting the BS that maximally contributes to the SCNR and establishing associations between BSs and user equipment (UE). A branch-and-bound (B&B) algorithm is employed to address the mixed Boolean nonlinear problem associated with BS-UE associations, specifically focusing on the mitigation of multi-user interference at each branching step. Further, transmit beamforming and receive filters are alternately optimized using the zero-forcing (ZF) method to enhance interference suppression. To ensure convexity in the multi-scale fractional objective function, the dual quadratic transform (QT) is applied. Simulation results validate the effectiveness of the proposed algorithm.