A Localization Framework for wireless mesh networks - Anchor-Free Distributed Localization in the DES-Testbed

Distributed localization has been in increased focus of research since the emergence of wireless multi-hop networks. One class of localization systems uses anchor-free algorithms, where no node in the network has information about its geographic position. None of the nodes acts as anchor and thus the algorithms have very limited requirements for the application in particular scenarios. The Anchor-Free Distributed Localization-Algorithm (AFL) by Priyantha et al. is such an algorithm that has been developed for applications in wireless sensor networks. It creates a relative coordinate system in the first phase and uses a mass-spring approach for the optimization of the nodes' locations in the second phase. In this publication we report our experiences implementing and using AFL in the DES-Testbed, an IEEE 802.11 based wireless mesh network. The Distributed Embedded Systems - Localization Framework for Testbeds (DES-LOFT) is introduced and discussed. It was developed for the implementation of localization systems as there is currently limited support for wireless mesh networks. DES-LOFT enables a holistic approach and interacts with other frameworks because a localization algorithm is never run independent from other services. Based on a first experiment series, we discuss the applicability of AFL in real world networks, propose improvements, and present preliminary results from experiments.