Reconfigurable intelligent surface (RIS) has shown its great potential in facilitating device-based integrated sensing and communication (ISAC), where sensing and communication tasks are mostly conducted on different time-frequency resources. While the more challenging scenarios of simultaneous sensing and communication (SSC) have so far drawn little attention. In this paper, we propose a novel RIS-aided ISAC framework where the inherent location information in the received communication signals from a blind-zone user equipment is exploited to enable SSC. We first design a two-phase ISAC transmission protocol. In the first phase, communication and coarse-grained location sensing are performed concurrently by exploiting the very limited channel state information, while in the second phase, by using the coarse-grained sensing information obtained from the first phase, simple-yet-efficient sensing-based beamforming designs are proposed to realize both higher-rate communication and fine-grained location sensing. We demonstrate that our proposed framework can achieve almost the same performance as the communication-only frameworks, while providing up to millimeter-level positioning accuracy. In addition, we show how the communication and sensing performance can be simultaneously boosted through our proposed sensing-based beamforming designs. The results presented in this work provide valuable insights into the design and implementation of other ISAC systems considering SSC.

翻译：可重构智能表面（RIS）在促进基于设备的集成感知与通信（ISAC）方面展现出巨大潜力，当前ISAC系统中感知与通信任务大多在不同的时频资源上执行。然而，更具挑战性的同步感知与通信（SSC）场景至今鲜有关注。本文提出一种新型RIS辅助ISAC框架，通过利用来自盲区用户设备接收通信信号中的固有位置信息来实现SSC。我们首先设计双阶段ISAC传输协议：第一阶段利用极有限的信道状态信息，同时实现通信与粗粒度位置感知；第二阶段利用第一阶段获得的粗粒度感知信息，提出简单高效的基于感知的波束赋形设计，以实现更高速率通信与细粒度位置感知。实验证明，所提框架可实现与纯通信框架几乎相同的性能，同时提供毫米级定位精度。此外，我们展示了如何通过所提出的基于感知的波束赋形设计同步提升通信与感知性能。本文研究成果为考虑SSC的其他ISAC系统的设计与实现提供了重要见解。