Transmit Beamforming Design for Noncoherent Distributed Integrated Sensing and Communication Systems

This paper presents a transmit beamforming design for distributed integrated sensing and communication (D-ISAC) systems. The proposed noncoherent D-ISAC system consists of multiple ISAC nodes that collaborate to perform both sensing and communication tasks without requiring phase-level synchronization. It utilizes coordinated multi-point (CoMP) transmission to enable the communication task. For sensing, the system takes advantage of both collocated and distributed multi-input multioutput (MIMO) radars to localize targets by estimating the angle-of-arrival (AOA) and time-of-flight (TOF). To design the transmit beamforming for the D-ISAC system, we adopt the CramerRao bound (CRB) as the sensing performance metric for target localization, while using the signal-to-interference-plus-noise ratio (SINR) as the metric for communication performance. We then formulate a D-ISAC beamforming design problem that minimizes the localization CRB while ensuring a minimum SINR level for each communication user. Numerical simulations demonstrate the performance gains of the proposed noncoherent D-ISAC system, highlighting improved CRB-SINR trade-offs compared to conventional single-node ISAC systems.