IRS-Aided Location Sensing and Beamforming in ISAC Systems: Distributed or Not?
Shuyang Lyu, Xiaoling Hu, Chenxi Liu, Mugen Peng
Abstract
Integrated sensing and communication (ISAC) has been envisioned as one of the key features of the sixthgeneration wireless networks. However, the coverage and sensingcommunication performance are limited due to the uncontrollable environments, especially when operating in the high-frequency bands. To address this issue, we utilize the benefits of intelligent reflecting surface (IRS) in reshaping the propagation environments and propose a distributed IRS-aided ISAC framework, in which the impacts of IRS deployment on both sensing and communication performances are investigated. Specifically, in the proposed framework, multiple IRSs including both passive IRSs (PIRSs) and semi-passive IRSs (SIRSs) are deployed to realize communication and sensing simultaneously. We first design a distributed IRS-aided location sensing scheme, by invoking communication signals. Using the sensed location information, a distributed-IRS beamforming scheme is designed to enhance the transmission rate with low overhead. Numerical results show that a high positioning accuracy of millimeter-level can be achieved. By using the sensed location information, the proposed distributed-IRS beamforming scheme achieves comparable performance to the benchmark with perfect channel state information. We also show that, with a fixed total number of IRS elements, a distributed deployment with 2 SIRSs is preferable in terms of location sensing performance and a distributed deployment with more PIRSs is preferable in terms of communication performance