Research On Data Transmission Scheduling In Wireless Body Area Network

Wireless body area network(WBAN)is composed of sensor nodes placed in the human body and surroundings.It is a kind of human-centered low-power wireless sensor network,which has wide application prospect in real-time medical monitoring.Unlike traditional battery-powered devices,sensor nodes can be powered by energy harvesting technology.The energy of the sensor nodes based on energy harvesting is sustainable,but the energy harvesting rate varies with time.In addition,realtime medical monitoring requires high timeliness of data.Therefore,for the purpose of meeting the requirements of energy and latency in WBAN,this thesis focuses on the data transmission scheduling for efficient data transmission in WBAN.The main contributions of this thesis can be summarized as follows:(1)Considering the time-varying characteristics of the energy harvesting rate,an energy self-adaptive MAC Scheduling Algorithm(ESAMS)is proposed.ESAMS adopts TDMA-based superframe structure to allocate time slot for sensor node dynamically according to energy harvesting rate.By adaptively adjusting the duty cycle of the sensor node to energy harvesting rate,the energy neutral operation is achieved.Simulation results show that the proposed ESAMS algorithm can improve the network throughput.(2)In order to realize the interference-free scheduling with minimum frame length for data convergecast in WBAN,a latency-aware shortest path tree is proposed as a route at the network layer,which exploits the sleep latency of links.In addition,a congestion degree based link scheduling algorithm(CDBLS)is proposed at the link layer.The scheduling algorithm colors the vertex in conflict graph in degrease order based on congestion drgee.Finally,according to the color of the vertex,time slots are allocated for links to ensure non-collision data convergecast.Simulation results show that the proposed CDBLS algorithm can reduce the convergence latency.(3)To solve the minimum latency broadcast scheduling issue in WBAN,an approximate minimum latency broadcast scheduling algorithm(AMLBS)is proposed.The proposal is divided into two parts,i.e.,broadcast tree construction(BTC)and non-leaf node first scheduling(NLNF).In BTC,sleep latency and the properties of independent node in graph theory are considered to determine the parent-child relationship among nodes,thus reducing the number of trnasmissions.In NLNF,broadcast scheduling is performed layer by layer to reduce the possibility of collision.Specifically,the non-leaf nodes in the layer are scheduled first and then the leaf nodes in the upper layer are scheduled.Simulation results show that the proposed AMLBS algorithm can reduce the broadcast latency.