How to Localize with a Single Radio Unit?

Compared to range- and angle-based localization, the importance of received signal strength (RSS)-based positioning is gradually diminishing in beyond 5G networks due to its limited localization accuracy, despite its simplicity. This paper explores the potential of utilizing non-line-of-sight (NLoS) RSS measurements to enhance the localization performance of RSS-based systems. Different from the conventional RSS-based localization, which relies solely on line-of-sight (LoS) RSS measurements, our findings reveal that the NLoS RSS also contains valuable locationrelated information for localization. A simple and efficient localization scheme that attains the Cramér-Rao lower bound (CRLB) performance is developed, accounting for measurement misalignment caused by different reflection paths. Furthermore, a tractable expression of the CRLB is analytically derived, which offers insights into how different network parameters, such as the path-loss decay and reflection loss, affect the fundamental limits of the proposed scheme.