Distributed TDMA for Mobile UWB Network Localization

Abstract

Many applications related to the Internet-of-Things, such as tracking people or objects, robotics, and monitoring require localization of large networks of devices in dynamic, GPS-denied environments. Ultra-WideBand (UWB) technology is a common choice because of its precise ranging capability. However, allowing access and effective use of the shared UWB medium with a constantly changing set of devices faces some particular challenges: high frequency of ranging measurements by the devices to improve system accuracy; network topology changes requiring rapid adaptation; and decentralized operation to avoid single points of failure.In this paper, we propose a novel Time Division Multiple Access (TDMA) algorithm that can quickly schedule the use of the UWB medium by a large network of devices without collisions in local network neighborhoods and avoiding conflicts with hidden terminals, all the while maximizing network usage. Using exclusively the UWB radio network, we realize a decentralized system for synchronization, dynamic TDMA scheduling, and precise relative positioning on a multi-hop network. Our system does not have special nodes (all nodes are equal) and it is sufficiently scalable for real-world applications. Our method can be applied to implement device localization services in a large spaces without GPS and complex topologies, like malls, museums, mines, etc. We demonstrate our method in simulation and on real hardware in an underground parking lot, showing the effectiveness of its TDMA schedule for relative localization.

A Survey of Robot Swarms’ Relative Localization Method

“…• UWB Cao et al [65] designed a fully distributed UWB relative localization scheme based on TDMA (time division multiple access) and a self-assembling network. It implements 12 nodes to construct a two-dimensional global map by relative localization.…”

“…Costa et al [91] proposed a distributed localization algorithm that includes global updates to conduct localization information to all nodes in order to solve the global map update problem. The localization method in the literature [65] considers node changes with global map updates in two dimensions, but the update frequency is slow and can only localize stationary targets.…”

“…In order to prevent communication congestion, we need to allocate channel resources reasonably and adopt polling multiple access technology. The polling mechanism can either allocate time slots for nodes using TDMA synchronously [65] or asynchronously using token passing [95], and the mechanism used is determined at the initialization time. Nodes use extensive communication broadcasts to initialize the whole system.…”

Ultra-Wideband Swarm Ranging Protocol for Dynamic and Dense Networks

“…There are also a few works focus on UWB swarm ranging for large numbers [19], [34], [36] or for high mobility [37], [38]. Corbalan et al [19] and Stocker et al [34] focus to locate countless tag by TDOA or by concurrent ranging.…”

“…Their work is dedicated to the anchor-tag model, not applicable for swarm scenarios. Cao et al [36] propose a novel Time Division Multiple Access (TDMA) algorithm that can quickly schedule the use of the UWB medium among a large network consisted of UWB-tagged nodes. Risset et al [37] investigate the UWB swarm ranging problem for rapid movements, with only two UWB tags.…”