Research Of Reliable Data Transmission Strategy In Wireless Body Area Networks

In the21th century, wireless communication has developed quickly, and entered into people’s work and life. With the development of high-performance, low-power and miniaturized sensor nodes, wireless body area network (WBAN) emerges for people focusing on healthcare. E-health based on remote medical monitoring provides an effective, low-cost, and convenient solution to health problem, helps allocate medical resource suitably to relieve public medical system press, and plays an important role in solving health problem. However, WBAN faces a few challenges, for example nodes energy limits and nodes traffic varying, especially transmission reliability caused by communication channel that are affected by human body energy absorption, and shadow effect resulting from body movements and posture varying. It is important to overcome channel fading and guarantee transmission reliability with the consideration of energy efficiency and traffic varying. Facing to WBAN challenges, we design the data transmission strategies to guarantee data transmission reliability and energy efficiency:(1) Firstly, we provide the reliable data transmission from reducing packet loss rate. With the consideration of channel characteristics, we design a hybrid strategy of slot allocation and relay. In single hop communication we schedule nodes slots position to get transmission reliability according to channel information; whereas facing to problem that single hop cannot solve, we use two hops communication to dynamically select relay node help data transmit. From the above two ways, we can obtain the robust reliable data transmission strategy. The strategy uses TDMA with dynamic slot allocation as medium access scheme to solve WBAN nodes data rate varying and energy efficiency, because TDMA has energy efficiency and allocating slots dynamically can satisfy nodes data rate varying. And selecting relay dynamically improves energy efficiency. Simulation results show that the proposed protocol has the lower packet loss rate than others, and it could guarantee nodes’transmission reliability that they claim.(2) Packet loss is inevitable, and then we propose a new way to solve transmission reliability problem from overcoming the effects caused by packet loss. A new solution to improve transmission reliability is to make up effects of packet loss. According to CS’s characteristics, we propose the CS transmission model that we divide signals into many segments, compress and transmit each segment, and improve reconstruction accuracy by controlling measurement number. However redundancy method doesn’t suit for relay transmission because it increases energy consumption to source node heavily and shortens the lifetime of WBAN, we propose the relay fusion method that shares the energy consumption to two nodes with fewer measurement number at each node. Simulation results show relay fusion method can reconstruct from fewer measurements with high accuracy and make up effects of packet loss easily. And moreover, Research One and Research Two can cooperate to provide strong transmission reliability with controlling measurement number in single hop communication, and using relay fusion method in two hops communication.