I. Introduction
The abundance of information provided by our smart devices can be exploited for IL-based services including tracking, healthcare-monitoring, and navigation [1], [2]. With the rise of the popularity of IoT battery-free devices comes the demand for accurate, scalable IL techniques leveraging energy efficient protocols such as BLE [3]. Localization systems are composed of mobile assets and anchor nodes for position calculation. IL presents a unique challenge: A greater emphasis for position estimation accuracy despite the high non-line-of-sight (NLOS) and multipath effects that cause signal deterioration, especially in environments such as warehouses and shipping facilities [2], [4], [5]. As such, successful IL techniques must utilise scalable wireless protocols with good indoor performance [2].