The Energy Balance Wireless Sensor Networks And Applications In Traffic Monitoring

As an emerging technique, wireless sensor network is the integrated technology of sensing measurement, network communications, micro-electromechanical system and embedded computing. Due to the small volume and the low price, the energy, processing capacity, storage capacity and the communication bandwidth of sensor nodes are limited. Additionally, the uneven network flow would lead to the much heavier burden of some sensor nodes. A few of nodes will run out of energy much faster than other nodes. The unbalanced node energy consumption will reduce the sensor network lifetime dramatically, so the balanced energy consumption methods which can utilize the node energy efficiently and prolong the lifetime of the wireless sensor network should be researched.Energy consumption model, topology control and routing algorithm of wireless sensor network are studied in this dissertation. A traffic information and transmission system based on Zigbee and wireless sensor network is built, and the sensor nodes used in traffic flow monitoring are developed. The new points of this dissertation are as follows:(1) In cellular and bin-packing coverage condition, the energy consumption and network lifetime model of heterogeneous surveillance sensor network are established. The optimum solution of the network lifetime model is obtained in the cellular coverage condition when the intra-cluster and inter-cluster key nodes almost run out of energy at the same time. An alternative working mode which can balance the energy consumption is proposed, and the network lifetime model in the conditions of the mode and bin-packing coverage is presented. Based on the network lifetime model, the minimum node density for satisfying a given lifetime constraint is gotten.(2) The topology control algorithms can simplify the redundant network, but almost all the existing algorithms neglect the stability of the wireless sensor network when simplifying the network. A fault tolerant topology control method is put forward in this dissertation. This method first generates the k-connected disjoint path between the sink node and the surveillance nodes. Then a relay node deploying algorithm is designed which deploy a minimum number of relay nodes in the k-degree spanning subgraph for the k-connectivity between every pair of sensor nodes. (3) Because the receiving energy consumption on wireless sensor networks routing algorithm have not been considered in past studies, a network model considering both the transmitting and receiving cost is presented in the dissertation. Based on the model, a new routing algorithm which provides the path with sufficient energy to complete the transmission task is presented. The algorithm prunes the network by shortest path computations and resets the cost weight by a cost evaluation function for balance the energy consumption. At the same time, the routing algorithm can maintain the network longer lifetime and reliable data transmission.(4) A traffic information and transmission system based on Zigbee and wireless sensor network is built, and the sensor nodes used in traffic information monitoring are developed. The results of the traffic flow surveillance experiment in the section of south city ring road and Yanta road of Xi'an show that the system and nodes are reliable and utilitarian.