Joint Beamforming and Power Control for D2D-Assisted Integrated Sensing and Communication Networks

Integrated sensing and communication (ISAC) is an emerging technology in next-generation communication networks. However, the communication performance of the ISAC system may be severely affected by interference from the radar system if the sensing task has demanding performance requirements. In this paper, we exploit device-to-device (D2D) communication to improve communication capacity of the ISAC system. The ISAC system in a single cell D2D assisted-network is investigated, where the base station (BS) performs target sensing and communication with multiple cellular user equipments (CUEs) as well as D2D user equipments (DUEs) simultaneously communicating with other DUEs by multiplexing the same frequency resource. To achieve the optimal communication performance in such D2D-assisted ISAC system, a joint beamforming and power control problem is formulated with the goal to maximize the sum rate while guaranteeing the performance requirements of radar sensing. Due to the non-convexity of the problem, we transform the origin problem into a relaxation form, then, a joint beamforming and D2D power control algorithm is proposed to obtain the solution efficiently. Particularly, a zero-forcing (ZF) beamforming scheme to eliminate the interference from the BS on DUEs is also proposed. Extensive numerical simulations demonstrated that with the assistance of the D2D communications, our proposed algorithm significantly outperforms the baseline schemes in terms of the system sum rate.