Integrated Sensing and Communication in IRS-Assisted High-Mobility Systems: Design, Analysis, and Optimization

In this paper, we investigate integrated sensing and communication (ISAC) in high-mobility systems with the aid of an intelligent reflecting surface (IRS). To exploit the benefits of Delay-Doppler (DD) spread caused by high mobility, orthogonal time frequency space (OTFS)-based frame structure and transmission framework are proposed. In such a framework, we first design a low-complexity ratio-based sensing algorithm for estimating the velocity of mobile user. Then, we analyze the performance of sensing and communication in terms of achievable mean square error (MSE) and achievable rate, respectively, and reveal the impact of key parameters. Next, with the derived performance expressions, we jointly optimize the phase shift matrix of IRS and the receive combining vector at the base station (BS) to improve the overall performance of integrated sensing and communication. Finally, extensive simulation results confirm the effectiveness of the proposed algorithms in high-mobility systems.

I. Introduction

Integrated sensing and communication (ISAC) has been identified as one of usage scenarios of sixth-generation (6G) wireless networks [1], [2], [3]. The ascent of ISAC is propelled by its capacity to meet the demands of advanced applications like the metaverse, intelligent robotics, and virtual reality, that require both high-speed data transmission and high-precision sensing [1]. Recently, ISAC also exhibits huge potential in Internet of Vehicles (IoV). On the one hand, IoV needs to sense various information for vehicle coordination. On the other hand, IoV requires the support of communication for vehicle networking. Hence, ISAC presents an effective solution to IoV by integrating sensing and communication under the same hardware and spectrum resources [4]. However, due to high-mobility of vehicles, there exists severe Delay-Doppler (DD) spread, degrading the performance of ISAC. It is imperative to design enabling ISAC techniques for high-mobility systems.