Theory And Application Research On High Energy Efficiency And Reliable Data Transmission For Wireless Sensor Networks

The rapid progress and combination of the micro-electro-mechanical systems (MEMS), embedded systems, computer networks and wireless communication technology has promoted the generation and rapid development of the wireless sensor network (WSN). WSN is usually composed of a large number of sensor nodes with the capability of wireless communication and computation in the form of self-organization. Synthesizing the information world in the logic with the real physical world, WSN has deeply changed the interaction mode between the human and the nature and has posed a profound impact on the modern science and technology. The fact that the nodes in WSN with rigorous resource constraint are often applied in the harsh environment brings a great variety of challenges to the WSN theory and its applications research.The energy-efficient and reliable data transmission mechanism, determining how the sensed data are delivered to the base station by multi-hop routing, is one of the basic and key issues in the WSN research and has a critical influence on the communication performance and energy efficiency of the network. Focusing on the nature of WSN, the research on energy-efficient and reliable data transmission theory and application technology is of great significance.In the aim of ensuring the reliability of the data transmission while improving the energy efficiency and on the basis of the geographical forwarding mechanism, in-depth research has been initiated on several theories and technologies including the routing collision optimization,cluster based reliable transmission and the trajectory based disjoint multipath reliable transmission, etc. Moreover, a fault diagnosis system of the online analyer based on WSN has been designed and implemented in accordance with the practical application requirements of industrial automation. The theoretical research results and innovative points are summarized as follows:1. According to the routing collision problem in the stateless geographical forwarding protocol, a routing collision optimization mechanism (FCEOS) based on the distributed fuzzy comprehensive evaluation is proposed, which combines distributed fuzzy comprehensive evaluation with the priority competition. On the basis of balancing several factors such as forwarding distance, link quality and the residual energy among all the next-hop candidate nodes, only a few nodes with better performance are selected out to participate in the competition for the next-hop forwarding, hence reducing the collision probability among the candidate nodes as well as improving the routing efficiency. Both theoretical analysis and experiment results demonstrate that FCEOS can effectively improve the energy efficiency of data transmission and reduce the transmission delay by optimizing routing collision,based on the original performance of stateless geographic forwarding protocol.2. Focusing on the high energy-consumption of redundant forwarding in existing multipath transmission protocol and based on the research results of FCEOS, the unit of geographical forwarding per-hop is expanded from a node to a cluster and two dynamic cluster-based reliable transmission mechanisms (CCRD and RCRD) are proposed in the thesis. In these two mechanisms, datas are all transmitted to the base station in the unit of a cluster. The transmission reliability is guaranteed by the collaboration among the cluster members and the energy consumption of the redundant transmission is reduced by constraining the number of cluster members. These dynamic clusters, established before data forwarding, will be automatically revoked after the task. Both theoretical analysis and experiment results demonstrate that these two mechanisms can ensure the reliability of data transmission, effectively improve the energy efficiency and reduce the transmission delay in contrast with existing work. In addition,CCRD is suitable for network with high dense node deployment while RCRD is suitable for sparser network.3. In order to implement the efficient real-time reliable transmission of the multimedia data streams in WSN, such as images and videos, etc. An elliptic trajectory-based disjoint multipath reliable forwarding mechanism (ETRF), based on the research results of RCRD, is proposed. Utilizing the geographical location information, ETRF is capable of constructing disjoint multiple uniformly distributed elliptic trajectories between the source nodes and the base station for the large block of multimedia streams which are divided into several smaller packet streams to be transmitted in parallel to the base station along different elliptic trajectories. ETRF combines the redundant multipath with the redundant coding mechanism and adopts the dynamic cluster-based reliable forwarding mechanism in every single path. Both theoretical analysis and experiment results demonstrate that the real-time performance, reliability and energy efficiency of multimedia streams transmission is effectively improved by ETRF in the dynamic network environment,comparing with the existing work.4. In accordance with the practical requirement of the industrial analyer on the fault diagnosis, a fault diagnosis system of the online analyer based on zigbee WSN has been designed and implemented.Firstly,the overall framework of system is designed according to industrial production organization.And layered fault diagnosis mechanism is proposed based on the framework,improving the diagnostic efficiency by assigning diagnostic task to different devices.Then in order to eliminate the effect of channel interference on the reliability of Zigbee network, a networking mechanism combining multi-network redundant hot-standby with terminal node internetwork switching is proposed.Finally,major hardware components and software modules of the wireless nodes and gateway are given in the thesis. In the actual operation, the system meets the requirement of analyer on the fault diagnosis.