Energy Optimization Based On Sleep Scheduling In Wireless Sensor Networks

Wireless sensor networks have been widely applied in many civilian and military applications.Although the application potential is limitless,each sensor is usually battery-powered and it is difficult to replace or recharge the batteries because of the harsh or hostile environment.The limited energy of nodes seriously constrains the network lifetime and the large-scale application.Hence,it is a key technical issue to improve the energy efficiency and increase the network lifetime.A broadly used method is to deploy the sensor nodes with high density.In such a high density network,not all sensors are required to perform the sensing tasks during the whole system lifetime.Making some nodes sleep does not affect the overall system function as long as there are enough active nodes to assure it.Besides,the high density network implies that node failures are more likely to occur which have an adverse effect on performance.This dissertation investigates the sleep scheduling technology to improve the energy efficiency and increase the network lifetime.The main work and innovations are as following:Firstly,a new sensing model is provided for coverage analysis.In this model,each sensor has three parameters: sensing range,communication range,private range.Using this model and Monte Carlo method,given the scale of deployment area and the number of sensor nodes,the ratio of the private range to the sensing range needed to obtain the desired coverage can be derived.Secondly,based on the coverage analysis,an energy-efficient distributed sleep scheduling scheme is proposed to prolong network lifetime while maintaining the desired sensing coverage,which does not need the knowledge about the geographic or neighbor information of nodes and thus can considerably reduce the cost of hardware and control overhead.The proposed scheme is also can handle uneven distribution and is robust against node failures.Simulation results fully demonstrate its efficiency and usefulness.The proposed sleep scheduling scheme can maintain desired coverage without any geographic or neighbor information and is robustness against node failures.The scheme also can reduce and balance and energy consumption thus can extend network lifetime effectively.