The Research On Lifetime Optimization Algorithms Of High Energy Efficient Wireless Body Area Network

As an important part of the internet of things (IoT) and the application ofwireless sensor network (WSN) to medical care, wireless body area network (WBAN)gradually becomes the focus of attention. Its portability and practicality facilitates itsbroad application prospect and huge economic benefits in medical monitoring,entertainment, military use, aerospace and other fields. Since WBAN is abody-centered network, it processes unique characteristics and requirements differentfrom that of WSN. However, the study of its key technologies is still in the infancy sofar, many problems remain to be solved.The energy of sensor nodes is strictly restrained since they are supplied bybattery with limited power. Therefore, on the basis of the research on energyefficiency, the formulation of fair optimization algorithm and the design of powercontrol mechanism for prolonging the lifetime of WBAN appear as the priorities andfocus of the research on WBAN, which not only has theoretical research significance,but also crucial practical value.In each time slot, only one sensor node is scheduled to transmit its measurementsdirectly to the access point (AP) through the fading channel. We formulate theproblem of dynamically choosing which sensor node should communicate with theAP to maximize network lifetime under the constraint of fairness as a constrainedMarkov decision process (CMDP). We propose a centralized transmission schedulingalgorithm that maximize network lifetime under the constraint of fairness. Theoptimal lifetime and optimal policy are obtained by Bellman equation in dynamicprogramming. The proposed algorithm defines the limiting performance in WBANlifetime under different degrees of fairness constraint and provides a benchmark forother scheduling algorithms. Due to the defect of large implementation overhead in acquiring global ChannelState Information (CSI), this thesis puts forward a distributed scheduling algorithmthat adopts local CSI, which saves the network overhead and simplifies the algorithm.It was demonstrated via simulation that this scheduling algorithm can allocate timeslot reasonably under different channel conditions to balance the performances ofnetwork lifetime and fairness.Finally, this thesis gives a discussion on the necessity of power controlmechanism on the basis of the dynamic characteristics of WBAN. The wireless linkquality can change rapidly in body area network, and a fixed transmit power results ineither wasted energy or low reliability. The dynamic power control mechanism canreduce energy consumption efficiently in the wireless communications and it works asthe main means to prolong the network lifetime. We propose a modified powercontrol mechanism based on the original one. The simulation results illustrate that themodified power control mechanism can further decrease the transmit power on thepremise of ensuring reliability of data transmission, meanwhile achieve goodperformance.The work mentioned above will provide a new method for the research onenergy efficiency and dynamic power control mechanism of WBAN, a new solutionfor maximizing network lifetime on the premise of ensuring fairness performance andcertain reference value for the research and development of WBAN.