The Research On Energy-efficient Transmission Strategy Based Power Control In Wireless Body Area Networks

With the continuous miniaturization and intelligentization of various sensors,and the rapid development of wireless communication technologies in recent years,the Wireless Body Area Network(WBAN)related to human body area has emerged.The convenience and practicality of the WBAN make it used in health care,entertainment,military operations and other fields widely.Because the battery capacity of the sensor nodes is extremely limited,frequent battery replacement will reduce the user experience.Therefore,the energy problem restricts the development of WBAN severely.In addition,the impact of human mobility on the wireless channel makes the energy saving problem more challenging in WBAN.In the WBAN,using a reasonable power control mechanism to improve energy efficiency becomes an important research direction in the future.Firstly,the research background,application scenarios and research status of the WBAN are introduced in the thesis.And the IEEE 802.15.6 standard is emphatically described,including physical layer technologies,access modes,inter-network interference processing technologies,and the wireless channel model in different application scenarios.Nextly,a power control algorithm for the channel characteristics of a single WBAN is proposed with the severely limited energy resources.The proposed algorithm does not require extra communication overhead.And the coordinator node broadcasts beacon frames with a fixed transmission power in the initial stage of each superframe.The sensor nodes obtain the current path loss estimation value according to the Received Signal Strength Indicator(RSSI)of the beacon frames.And get the the current path loss actual value by the RSSI of the reply frame,the sensor nodes dynamically adjust the path loss weight factor in order to reduce the path loss estimation error.At the same time,under the premise of ensuring transmission reliability,the sensor nodes select the optimal transmission power value according to the channel state,so that the amount of data transmitted per unit energy is maximized,and the purpose of optimizing the performance of the WBAN is achieved.Simulation results show that the proposed algorithm could reduce the average number of each data packet transmission and the waste of transmission energy effectively,which results in the improvement of the energy efficiency in the WBAN.Finally,in order to solve the problem of the inter-network interference in multiple WBANs under mobile scenario,a power control algorithm with node-discriminated is proposed.According to the current channel state and Quality of Service(QoS)requirements,each WBAN establishes the different cost function and further constructs a WBAN power control game model.And then using Nash equilibrium to select the best transmit power of each WBAN.Simulation results also show that the proposed algorithm could effectively reduce the inter-network interference of WBANs,and further avoid the waste of sending energy in the nodes.