Optimized Energy Management In Wireless Powered Body Area Networks

Wireless body area network(WBAN)is a network comprised of sensors around or inside human body,and WBAN has wide application prospects in health care,electronic entertainment,military,public security and so on.WBAN utilizes energy harvesting technology to capture energy from ambient environment,enabling sensors to get away from the limit of the energy supply derived from batteries.Optimized energy management is an important issue in WBAN as well as a critical link to optimize the overall performance of network.In this dissertation,we study the energy management optimization of WBAN from the perspectives of energy collection and utilization.On the one hand,the mobility of the human brings both challenges and possibilities for our optimization in which we need to deploy chargers according to the mobility model of human to satisfy the power requirements of users.On the other hand,to improve the throughput of the system,changes of body posture result in the fluctuation of harvesting and channel condition,which should be considered when utilizing the harvested energy to transmit data.Base on the above-mentioned issues,the major work of this dissertation is as follows:1.Base on users' mobility model and the limit of energy storage capacity,we propose a charger deployment optimization algorithm.Firstly,we characterize users' mobility model as a set of trajectories and stay points.Then,we study how to minimize the total number of deployed chargers to satisfy the power requirements of users according to the mobility model.At last,we propose a Three-Stage Charger Deployment(TSCD)algorithm.We fulfill the power requirements first at stay points,then on trajectories,and finally a given survival probability in the network is guaranteed.The effectiveness of TSCD is confirmed by simulation.2.Based on dynamic energy harvesting and channel condition,we propose a dynamic scheme by increased or decreased the frame length and the number of redundant frames.Firstly,the optimal combination of the frame length,the number of redundant frames and the charging time that maximized the throughput was obtained by solving the formulated throughput optimization problem.Then a dynamic frame and charging time adaptation(DFCTA)scheme was proposed,which increased or decreased the frame length and the number of redundant frames at runtime based on the throughput measurement at the reader.Simulation results showed that by DFCTA scheme,the throughput performance was remarkably improved compared with current fixed-frame-length scheme in EPC Gen2 protocol and was close to the theoretical optimum under different energy harvesting and channel conditions.