Reconfigurable Intelligent Surface assisted Integrated Communication, Sensing, and Computation Systems

This paper studies a mobile edge computing (MEC) assisted integrated sensing and communication (ISAC), where reconfigurable intelligent surface (RIS) is used to alleviate the attenuation of communication links during computational offloading. In this paradigm, the dual function radar and communication (DFRC)-enabled user equipments (UEs) simultaneously perform radar sensing and communication tasks, facilitating the offloading of partial computational tasks to an edge computing server (ECS) through an RIS. To satisfy the critical need for time-efficient sensing, we investigate the latency minimization problem for both single-UE and multi-UE scenarios, subject to constraints on UEs' transmit power, radar signal-to-interference-plus-noise-ratio (SINR), RIS phase shift, and computation capability. To address the formulated non-convex problem, we propose an algorithm based on the block coordinate descent (BCD) method to decouple the original problem into two subproblems, where the computational and beamforming settings are optimized alternately. Specifically, we employ the Lagrangian method for the optimization of computational settings. In addition, two equivalent transformations are applied to transform the objective function (OF) of the subproblem for active and passive beamforming into a form of weighted sum-rate. Then, a combination of minimum variance distortionless response (MVDR), successive convex approximation (SCA), majorization-minimization (MM), and weighted minimum mean-square error (WMMSE) techniques are applied to tackle this subproblem. Moreover, a closed-form solution is obtained in the simplified single UE scenario. Finally, simulation results substantiate the effectiveness of the proposed system.