Cooperation Enabled Joint Synchronization and Localization Services in WSN

Synchronization and localization are fundamental requirements for WSN applications. The entangled nature of positioning and timing requires a joint solution. The existing solutions typically require multiple rounds of message exchanges from multiple anchor nodes to provide precise positioning and timing services, which is problematic for target nodes. Aiming at providing precise timing services to moving targets, we first proposed a local timing method by using the estimated clock parameters obtained from the only one-round message exchange to scale the imperfect internal clock skew. This scaling operation makes the local clock count time in a more ideal way, i.e., with the scaled skew value close to one. We then analyzed the fundamental cause of local clock drift and proposed a WSN-based clock calibration method to guarantee the precision of the timing service of the target node. This method takes the uncertainty in clock estimation as a pivotal factor in constructing the belt-shape WSNs, and the mobility of the target node to cooperatively use the anchor nodes deployed in different regions. A set of numerical simulations was carried out to validate the proposed method. The obtained results confirm the effectiveness and robustness of the proposed method.