IEEE TRANSACTIONS ON SIGNAL PROCESSING 1 Relative Location Estimation in Wireless Sensor Networks

Self-configuration in wireless sensor networks is a general class of estimation problems which we study via the Cramér-Rao bound (CRB). Specifically, we consider sensor location estimation when sensors measure received signal strength (RSS) or time-of-arrival (TOA) between them-selves and neighboring sensors. A small fraction of sensors in the network have known location while the remaining locations must be estimated. We derive CRBs and maximum-likelihood estimators (MLEs) under Gaussian and log-normal models for the TOA and RSS measurements, respectively. An extensive TOA and RSS measurement campaign in an indoor office area il-lustrates MLE performance. Finally, relative location estimation algorithms are implemented in a wireless sensor network testbed and deployed in indoor and outdoor environments. The measurements and testbed experiments demonstrate 1 m RMS location errors using TOA, and 1 m to 2 m RMS location errors using RSS. I.