IRS-Aided High-Accuracy Positioning for Autonomous Driving Toward 6G: A Tutorial

The increasing number of vehicles on the road places high demands for autonomous driving in future intelligent transportation systems (ITSs). To realize automated services in ITSs, high-accuracy positioning is increasingly important, while positioning simultaneity for high-mobility vehicles should be guaranteed. Existing positioning systems have many constraints in locating vehicles in urban environments, making it difficult to meet the performance requirements. With the development of 6G, massive numbers of high-frequency base stations (BSs) are expected to be deployed to ensure connectivity and benefit positioning performance. However, high-frequency signals have severe distance attenuations and strong sensitivity to the non-line-of-sight (NLoS) environment that is prevalent in cities. Intelligent reflecting surface (IRS), with its ability to control signal reflections and create beyond-LoS communications, is a promising technology to improve positioning performance in urban vehicular networks. In this article, we discuss the existing positioning systems and explain the potentials of IRS for future BS-enabled positioning systems. We also provide an example to illustrate how to optimize the performance of IRS-aided vehicle positioning systems. Furthermore, we highlight important issues and give future directions.