Searching for a lion in the desert: optics-based acquisition algorithms for wireless sensor networks

In this paper we address the task of locating and mapping sensor nodes equipped with passive optical transmitters deployed within a wireless sensor network. The passive transmitter is in the form of a modulatable corner cube retro-reflector (CCR) and is interrogated by a base station equipped with a variable sized laser beam prior to data harvesting using optical wireless communication. We propose and discuss an efficient acquisition algorithm based on the binary search concept and evaluate its performance in locating a solitary sensor node. We demonstrate the use of an analytical tool for assessing the acquisition cost for different error probability distributions and search regimes. The common line-of-sight (LOS) requirement for both sensor location and data harvesting renders the need for individual sensor node identification redundant and thus yields a simplified search regime by comparison with previously published research on node localisation.