Study On Resource Allocation Mechanism In Radio Frequency Power Transfer Based Wireless Body Area Network

Wireless body area network is a type of wireless sensor network which consists of several miniature low-power sensor nodes and actuators.All these sensor nodes and actuators are deployed in or on human body.Wireless body sensor network is widely applied in medical care,sports,military and personal entertainment etc.Especially in medical care,the application is really pervasive.Wireless body area network can continuously monitor vital physiological signals of human body which can reflect the health condition.It can also transmit the sensory data to the remote medical server and diagnose potential diseases by the big data in the server.This can help doctors cure diseases and patients know their physical conditions,thus can prevent diseases effectively.Besides improving the quality and efficiency of medical service,wireless body sensor network can also decrease the cost of medical treatment.Therefore,the research on wireless body area network has great meaning.Since doctors have to know the physiological signals of patients and patients have to know their health condition at any time,the duration of wireless sensor network is really important.However,most of the sensor nodes in wireless body area network are small which results in the limited capacity of the batteries in sensor nodes.In addition,some of the sensor nodes are deployed in human body.Thus,regularly replacing the batteries is inconvenient or even infeasible.This makes network lifetime become a great problem for wireless body area network.Recently,the popular energy harvesting technology provides a potential to break the battery limitation of wireless body area network.However,because the energy source of energy harvesting technology is the natural environment,the power supply is unstable and inefficient which cannot guarantee the longevity and efficiency of wireless body area network.Besides the energy harvest technology,wireless power transfer technology can also supply power for wireless body area network.Since it is an active power supply method,it is not constrained by the natural environment,thus can provide sustainable and sufficient energy for sensor nodes.It provides a new direction for solving the lifetime problem of wireless body area network.Along with the advantages,the introduce of wireless power transfer technology in wireless body area network also has many new challenges.It makes the network resource structure of wireless body area network more complex,which results in severely unfair resource allocation problem.In wireless body area network,all the physiological data is indispensable for patient.The error of data transmission of any sensor node may be life-threatened for patients.Therefore,how to allocate resource allocation efficiently and fairly is really an important problem for wireless body area network.For the durable and reliable service requirements of wireless body area network,this paper applies wireless power transfer technology in wireless body area network.From the perspective of the resource allocation problem in wireless body area network,in order to improve the system fairness and efficiency,this paper research on the resource allocation mechanism:(1)According to the characteristics of different types of wireless power transfer technology and the energy supply requirement of wireless body area network,the electromagnetic radiation is applied in wireless body area network.Based on the existing researches,a multiple RF power beacons wireless powered body area network system model is proposed,including channel model,power transfer model and information transmission model.(2)According to the Pareto optimality of the cooperative game,the proposed system model is combined with the bargaining model in the cooperative game theory,and a resource allocation mechanism based on Nash bargaining model is proposed.The characteristics of Nash bargaining solution are utilized to establish the resource allocation problem,and dual decomposition method is used to solve the problem.By comparing the simulation results of other resource allocation mechanisms,the efficiency and fairness of the system operating under the proposed Nash bargaining mechanism are proved.(3)Due to the limited computing capacity of the sensor nodes in wireless body area network and the centralized characteristic of Nash bargaining mechanism,the access point(AP)that receives physiological data from sensor nodes is selected as the central resource manager to uniformly manage the resource allocation among the network devices.Furthermore,a resource scheduling algorithm is designed for the AP to enable it to efficiently schedule the network resource for the devices and determine the time slots that different devices operate in.