WiFi ad-hoc mesh network and MAC protocol solution for UWB indoor localization systems

Ultra-wideband (UWB) is an emerging technology that is well known for its capability to provide centimeter positioning precision which is essential for applications that require very high accuracy. However, although several accuracy improving algorithms have been proposed in scientific literature, solutions to improve the scalability (in terms of coverage and dense user deployments) have not been explored yet or are still under examination. To this end, this paper presents a WiFi-UWB solution in which the UWB indoor localization system is deployed on top of a WiFi ad-hoc mesh network. The combination of a high-throughput WiFi mesh backbone in combination with a high-accuracy UWB radios allows deployment in areas without existing (wired) backbones. Moreover, the possibility for the clients to move around the covered area maintaining fully connectivity (roaming feature) is implemented. Finally, to improve scalability, a Time Division Multiple Access (TDMA) MAC protocol that combines WiFi and UWB technologies is proposed, thereby improving the scalability of the network towards multiple mobile users. As such, the solution combines the strengths of the WiFi technology (high throughput and efficient multi-hop meshing with roaming) with the main strengths of UWB (high accuracy localization). Overall the system supports 100 simultaneous clients while supporting multi-hop roaming with 150 ms delays.