Improved Footprint Modeling for Wireless Sensor Networks Changfei Chen and Jeff Frolik University of Vermont, Burlington, VT, 05405 E-mail: cchen4@uvm.com Introduction In order for a wireless sensor network to provide its requisite data, connectivity between nodes must be ensured. However, to date, the models used to analyze a sensor’s radio communication footprint have been overly simplistic (i.e., isotropic) and thus yield results not found in practice. In this work, a ‘weak-monotonicity’ (WM) model is leveraged to represent a footprint’s non-isotropic behavior. In particular, the usability of the WM footprint in a log-shadowing propagation environment is considered through analysis and simulation. We then develop an enhanced footprint which overlays multiple WM patterns. Weak-Monotonicity Model The ‘weak-monotonicity’ communication footprint model was recently introduced [1] to address the aforementioned shortcomings of the traditional disk model (i.e., isotropic coverage). In the WM model (Fig.1), if node i is connected to node j, then i will be connected to any node k with property ( ) ( ) ( ) , cos , dik A dij ≤ ⋅ , where A jik =∠ . The footprint of the each sensor is therefore a circle with the sensor itself on the boundary and diameter of the distance from the sensor to its farthest connected neighbor. Within the boundary, the connectivity was assumed in [1] to be 100% and outside the boundary 0%. Figure 1. ‘Weak-Monotonicity’ Model Log-Normal Shadowing Model To address the non-realistic assumption of full connectivity within the footprint, we leverage the log-normal shadowing model which has long been used for mobile communications [2] and more recently to model wireless sensor network Figure 2. Geometry for usability analysis of WM model 978-1-4244-2042-1/08/$25.00 ©2008 IEEE