Adaptive Sensor Activity Scheduling in Distributed Sensor Networks: A Statistical Mechanics Approach

Abstract

This article presents an algorithm for adaptive sensor activity scheduling (A-SAS) in distributed sensor networks to enable detection and dynamic footprint tracking of spatial-temporal events. The sensor network is modeled as a Markov random field on a graph, where concepts of Statistical Mechanics are employed to stochastically activate the sensor nodes. Using an Ising-like formulation, the sleep and wake modes of a sensor node are modeled as spins with ferromagnetic neighborhood interactions; and clique potentials are defined to characterize the node behavior. Individual sensor nodes are designed to make local probabilistic decisions based on the most recently sensed parameters and the expected behavior of their neighbors. These local decisions evolve to globally meaningful ensemble behaviors of the sensor network to adaptively organize for event detection and tracking. The proposed algorithm naturally leads to a distributed implementation without the need for a centralized control. The A-SAS algorithm has been validated for resource-aware target tracking on a simulated sensor field of 600 nodes.

Keywords:

• Wireless Sensor Networks (WSN)
• Sleep/Wake Scheduling
• Target Tracking
• Markov Random Fields
• Ising Model
• Self-Organization

This work has been supported in part by the U.S. Army Research Laboratory and the U.S. Army Research Office (ARO) under Grant No. W911NF-07-1-0376, and by the U.S. Office of Naval Research under Grant No. N00014-08-1-380; and by NASA under Cooperative Agreement No. NNX07AK49A.

Notes

¹Known as generalized canonical distribution in Statistical Mechanics, where it is derived as an unbiased distribution of microstates subject macroscopic observations, such as energy [30].

²A clique potential is called anisotropic (isotropic) when it is dependent (independent) of the clique orientation [29].

³For w = 0, = p∗ = 0.3 for all i ≠ 0 and for node s ₀. Thus