Reconfigurable Intelligent Surfaces for Localization: Position and Orientation Error Bounds

Next-generation cellular networks could witness the creation of smart radio environments (SREs), where walls and objects will be coated with reconfigurable intelligent surfaces (RISs) to strengthen communication localization performance. In fact, RISs have been recently introduced not only overcome blockages due obstacles but also for high-precision mobile users in GPS denied environments, e.g., indoors. Towards such a vision, this paper presents performance limits scenarios single next generation NodeB base station (gNB), equipped multiple antennas, infers position orientation user equipment (UE) surface (RIS)-assisted environment (SRE). We consider signal model that is valid near-field propagation conditions, as usually adopted far-field assumption does always hold, especially large RISs. For considered scenario, we derive Cramér-Rao lower bound (CRLB) assessing ultimate synchronous asynchronous signalling schemes. addition, propose closed-form RIS phase profile well suits joint localization, perform extensive numerical results assess our scheme various design. Numerical show proposed can achieve remarkable even signalling, design, based on signal-to-noise ratio (SNR), approaches optimal design minimizes CRLB.