Node deployment in large wireless sensor networks: coverage, energy consumption, and worst-case delay

Node deployment is a fundamental issue to be solved in Wireless Sensor Networks (WSNs). A proper node deployment scheme can reduce the complexity of problems in WSNs as, for example, routing, data fusion, communication, etc. Furthermore, it can extend the lifetime of WSNs by minimizing energy consumption. In this paper, we investigate random and deterministic node deployments for large-scale WSNs under the following performance metrics: coverage, energy consumption, and message transfer delay. We consider three competitors: a uniform random, a square grid, and a pattern-based Tri-Hexagon Tiling (THT) node deployment. A simple energy model is formulated to study energy consumption for each deployment strategy. Using basic geometry we propose a novel strategy for calculating the relative frequency of exactly k-covered points, which uses k-coverage maps, for both a square grid and THT. To model and consequently control the worst-case delay of a given WSN we build upon the so-called sensor network calculus (a recent methodology introduced in [7]). Finally, we analyze tradeoffs between these performance metrics for each deployment strategy to show which strategy is preferable under what factors, e.g., the number of nodes.