Joint beamforming and transmit power control for maximizing uplink communication rate of active IRS-assisted ISAC...

Existing studies related to active intelligent reflecting surface (IRS)-assisted integrated sensing and communication (ISAC) systems generally focus on sensing performance optimization in downlink communication scenarios, and there lacks research that explores the potential of active IRS to boost the communication performance under the sensing performance constraints in more complex uplink communication scenarios. Inspired by the current situation mentioned above, this paper constructs the uplink communication rate maximization problem for active IRS-assisted uplink ISAC system. With the aim of solving the constructed highly non-convex problem involving strong coupling among multiple optimization variables, a joint beamforming and transmit power control strategy is proposed in this paper. The Lagrangian dual transformation and fractional programming methods are first applied to simplify the objective function, and then the optimization variables are solved iteratively by alternating optimization algorithm, maximization-minimization algorithm, and semidefinite relaxation algorithm. Simulation analysis demonstrates that compared to the passive IRS benchmark strategy and the two random configuration strategies, the strategy presented in this paper has the ability to achieve 27.3%, 9.5% and 11.4% user uplink communication rate enhancement ratios, respectively. Additionally, under a fixed total power budget, increasing the maximum transmit power of the dual functional radar-communication base station may impair the communication performance.