Robust Localization Protocols and Algorithms in Wireless Sensor Networks Using UWB
Di Wu, Lichun Bao and Renfa Li
Localization has many important applications in wireless sensor networks (WSNs). A variety of technologies, such as acoustic, infrared, and UWB (ultra-wide band) media have been utilized for localization purposes. In this paper, we propose a holistic, bottom-up design of a UWB-based communication architecture and related protocols for localization in WSNs. A new UWB coding method, called U-BOTH (UWB based on Orthogonal Variable Spreading Factor and Time Hopping), is utilized for minimum interference communication, and an ALOHA-type channel access method and a message exchange protocol are used to collect sensor location and signal strength information in WSNs. After establishing the UWB path loss model, we apply the maximum likelihood estimation (MLE) method to compute the distances between neighbor nodes using the RSS information. Then, we propose NMDS-MLE (Non-metric Multidimensional Scaling and Maximum Likelihood Estimation) localization algorithms by matching the sensor coordinate estimates with the distance estimates derived from the path loss model. The performance of the system is validated using theoretic analysis, simulation and real testbed experiments.
Keywords: Orthogonal Variable Spreading Factor (OVSF), Time Hopping (TH), Ultra-Wide Band (UWB), localization, ranging