A semi-distributed localization protocol for wireless sensor and actor networks

We consider a wireless sensor and actor network (WSAN) consisting of a large number of tiny, low-cost sensors uniformly and independently distributed in a two-dimensional geographical region around a few powerful entities, called actors. To save energy, the sensors operate according to sleep/awake schedules in an asynchronous manner. In this setting, we propose a semi-distributed, actor-centric localization algorithm which organizes the sensors in the vicinity of each actor by means of a discrete polar coordinate system. Specifically, each sensor is localized when it acquires the corona and sector coordinates of the region it resides in. To accomplish the localization task, each actor first trains a subset of sensors in its vicinity, which in turn train their neighbors. By modeling the deployed sensors as a two-dimensional Poisson point process and applying well-known results from the Coupon Collector´s problem and Chernoff bounds, we derive bounds on the sensor density required to localize with high probability all sensors in the actor´s vicinity. Finally, we verify the analytical bounds with results from our simulation experiments.