Concurrent Ranging with Ultra-Wideband Radios: From Experimental Evidence to a Practical Solution

To enable future location-aware Internet of Things (IoT) applications, Ultra-wideband (UWB) technology provides centimeter-accurate distance estimations. In the common case of a non-synchronized network, at least N·(N-1) message exchanges are required to derive the distance between N nodes. Enabling concurrent ranging between an initiator and an arbitrary number of responders can drastically reduce the amount of necessary transmissions and hence increases the efficiency of UWB systems. Although the feasibility of concurrent ranging has been proven experimentally, several key challenges still need to be addressed to practically implement concurrent ranging in real-world UWB systems, such as the automatic detection of multiple responses, the identification of a responder, as well as the detection of overlapping responses (especially in the presence of multipath components). In this paper, we provide a concurrent ranging solution tackling the aforementioned challenges. Among others, our solution enables (i) to detect responses in the CIR reliably, (ii) to encode the responder ID in the CIR to allow personalized ranging, as well as (iii) to mitigate the impact of overlapping responses and multipath components. We further show how the proposed solution increases the scalability of concurrent ranging in real-world UWB-based distributed systems.