Leveraging RIS-Enabled Smart Signal Propagation for Solving Infeasible Localization Problems

Abstract

Reconfigurable intelligent surfaces (RISs) have tremendous potential for both communication and localization. While communication benefits are now well-understood, the breakthrough nature of the technology may well lie in its capability to provide location estimates when conventional approaches fail, (e.g., due to insufficient available infrastructure). A limited number of example scenarios have been identified, but an overview of possible RIS-enabled localization scenarios is still missing from the literature. In this article, we present such an overview and extend localization to include even user orientation or velocity. In particular, we consider localization scenarios with various numbers of RISs, single-or multi-antenna base stations, narrowband or wideband transmissions, and near-and farfield operation. Furthermore, we provide a short description of the general RIS operation together with radio localization fundamentals, experimental validation of a localization scheme with two RISs, as well as key research directions and open challenges specific to RIS-enabled localization and sensing.

Performance of RIS-Aided Nearfield Localization under Beams Approximation from Real Hardware Characterization

“…3 Department of Electrical Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden. 4 Department of Informatics and Telecommunications, National and Kapodistrian University of Athens (NKUA), 15784 Athens, Greece.…”

“…They are indeed expected to reinforce both the service continuity and the Quality of Service (QoS) of communication networks, or even to locally boost their performance on demand, while limiting the need for additional costly elements of infrastructure (e.g., active base station (BS)). Although they were mostly intended to extend coverage under severe radio blockages, they have also shown fine capabilities to purposely shape the wireless propagation channel in a variety of location-dependent applications, such as user equipment (UE) localization (in both geometric nearfield (NF) and far field (FF) regimes), physical environment mapping and distributed spectrum sensing, or limitation of unintentional radio emissions (e.g., for improved communication security or reduced field exposure) [3,4].…”

RIS Position and Orientation Estimation via Multi-Carrier Transmissions and Multiple Receivers

“…This feature renders RISs as enablers of programmable signal propagation, motivating the concept of smart wireless environments [4], which can be exploited for offering coverage extension as well as localization and mapping [5]. In most cases, RISs are deployed as anchors with known locations and orientations, and can support or enable user localization; this is called RIS-aided or RISenabled localization [6]. In addition, RISs can be carried by a user to enable its semi-passive localization [7].…”

Performance of RIS-aided near-field localization under beams approximation from real hardware characterization

“…They are indeed expected to reinforce both the service continuity and the QoS of communication networks, or even to locally boost their performance on demand, while limiting the need for additional costly elements of infrastructure (e.g., active (BS)). Although they were mostly intended to extend coverage under severe radio blockages, they have also shown fine capabilities to purposely shape the wireless propagation channel in a variety of location-dependent applications, such as (UE) localization (in both geometric (NF) and (FF) regimes), physical environment mapping and distributed spectrum sensing, or limitation of unintentional radio emissions (e.g., for improved communication security or reduced field exposure) [3,4].…”