Asynchronous Location Tracking Algorithms for Distributed Power-Saving Wireless Sensor Networks

In recent years, energy conservation has been considered as an important topic within the wireless sensor networks (WSNs). How to extended the network lifetime with cost-effective management is the primary concern within the design of power- saving mechanisms for WSNs. In this paper, with the consideration of energy conservation, two location tracking algorithms are proposed in the distributed WSNs in order to trace a mobile station that is not synchronized with the corresponding sensor nodes (SNs). The scheduled power-saving tracking (SPT) scheme is first proposed for the SNs to trace the MS´s beacon instants and consequently to track its movement in a power-saving manner. Coordinators are selected to manage and collect the information for location estimation and tracking of the MS. The predicted information with respect to the MS´s movements is obtained by the coordinator in order to notify specific hearable SNs for receiving the MS´s next beacon. Moreover, the geometry-assisted power-saving tracking (GPT) algorithm is proposed to further conserve the energy of the SNs. With the consideration of the geometry dilution of precision effect, only specific three SNs will be selected for the computation of MS´s positions. Performance comparison of the proposed schemes are conducted by observing both the power efficiency and tracking accuracy under varied MS´s velocities. Compared to the SPT scheme, numerical results show that the proposed GPT algorithm can effectively extend the network lifetime and also achieve comparable tracking accuracy.