MAC Protocol for Supporting Multiple Roaming Users in Mult-Cell UWB Localization Networks

Indoor positioning systems (IPS) aim to track objects, people or assets with the highest possible accuracy. In literature, it has been shown that among radio-frequency based technologies, ultra-wideband (UWB) is capable of providing em-level accuracy. However, this technology is not yet mature when it comes to large-area coverage and multi-user support. To remedy this, this paper proposes a TDMA protocol for a large scale localization network with numerous simultaneously active users. To this end, a full system was designed that handles the scheduling of the transmissions, the synchronization of the fixed nodes and the roaming of the mobile nodes. Moreover, the performance of the system has been analyzed by simulations using OMNeT++ and INET framework. The simulation was improved with real life experiments and has been used to evaluate full TDMA/TDoA approach. Our solution improves the scalability to 88.3 % effective spectrum usage, compared to only 18.6% when using ALOHA, while mobile nodes are able to roam successfully in 90% of the handovers.