We consider transmit beamforming and reflection pattern design in reconfigurable intelligent surface (RIS)-assisted integrated sensing and communication (ISAC) systems to jointly precode communication symbols and radar waveforms. We treat two settings of multiple users and targets. In the first, we use a single RIS to enhance the communication performance of the ISAC system and design beams with good cross-correlation properties to match a desired beam pattern while guaranteeing a desired signal-to-interference plus noise ratio (SINR) for each user. In the second setting, we use two dedicated RISs to aid the ISAC system, wherein the beams are designed to maximize the worst-case target illumination power while guaranteeing a desired SINR for each user. We propose solvers based on alternating optimization as the design problems in both cases are non-convex optimization problems. Through a number of numerical simulations, we demonstrate the advantages of RIS-assisted ISAC systems. In particular, we show that the proposed single-RIS assisted ISAC system improves the minimum user SINR while suffering from a moderate loss in radar target illumination power. On the other hand, the dual-RIS assisted ISAC system improves both minimum user SINR as well as worst-case target illumination power at the targets, especially when the users and targets are not directly visible.

翻译：我们考虑在可重新整合的智能表面(RIS)辅助综合遥感和通信系统(ISAC)中,在联合预先编码通信符号和雷达波形系统(ISAC)中传送光成和反射模式设计;我们处理多种用户和目标的两种设置;首先,我们使用单一的RIS来提高ISAC系统的通信性能,设计具有良好的交叉关系特性的光束,以匹配理想的光束模式,同时保证每个用户都拥有理想的信号对干涉和噪音比率;在第二种情况下,我们使用两个专用的ISAC系统来帮助ISAC系统,其中的光束旨在最大限度地扩大最坏情况的目标照明能力,同时保证每个用户都拥有理想的SINR;我们使用一个单一的RI系统来提高最小用户对干涉的信号和噪音比率(SINR),我们提出基于交替优化的解决方案,因为这两种情况下的设计问题都是非convex优化问题;我们通过一些数字模拟,我们展示了ISAC系统的好处;特别是,我们表明,拟议的单一IRS系统在雷达目标中遭受中度损失的最小损失时帮助的SINRR,特别是作为最低指标目标的双重目标用户在SIRA得到协助。