Modular Topology Control and Energy Model for Wireless Ad Hoc Sensor Networks

Networked wireless sensors in a harsh terrain typically are battery operated and, therefore, require energy efficient network protocols. In order to ease the analysis of the energy usage of proposed network protocols, this paper proposes an energy module, implemented in OPNET, to determine the energy consumption over time during network simulation. Multiple energy consumption modes, such as transmit, idle, sleep modes are all accounted for. A sensor node will be automatically turned off (disabled) in the middle of simulation if it runs out of the user-specified energy. The energy module provides function calls for network protocols implemented in OPNET, and therefore allows performance evaluation in terms of the energy efficiency. Among other protocols, this paper focuses on the topology control schemes, which has individual wireless sensors determine their own transmission power levels while maintaining network connectivity. In order to allow the adjustment of transmission power level having an effect on the transmission range, this paper investigates necessary modifications on the Closure Pipeline stage in OPNET. A simple topology control scheme is implemented for validation purposes. Simulation results will be presented in this paper to exhibit the effect of the closure stage modification as well as the energy modules.