Research On Technologies Of Routing And Localization In Wireless Sensor Networks

Wireless sensor networks is a multiple hops and self-organizing network which is formed through wireless communication by a large number of microsensor nodes that have capacities of awareness and computing. It is a new technology which is integrated the function of data acquisition, data processing and data transmission. WSN has many features such as flexible deployment,strong fault tolerance, low cost, and so on. It is widely used in the national defense and military, environmental monitoring, industrial control, disaster rescue, and other fields.At present, in the technical problems of wireless sensor networks, routing protocol is aimed to find the optimal path from the source node to the destination node, and realize the reliable and stable transmission of the data. It is the foundation and guarantee of the communication. Node localization technology is to pinpoint the location of the unknown nodes which were random distributed in the surveillance area, so that people can know the exact location of the event. In order to solve the two key technical problems above, this paper summarizes and analyzes the existing researches, and has an intensive study on the routing protocol and node localization technology.The main contributions of this paper include the following aspects:(1) This paper proposes a QoS routing protocol based on the ant colony algorithm. In the transition probability formula for choosing the next-hop node,the new algorithm considers both the distance factor and the energy factor,which can effectively balance the energy of the network. In addition, in order to satisfy the QoS requirements, the pheromone updating rule takes into account the reserved bandwidth and delay constraints at the same time. Simulation experiments show that the new protocol has good performance both in the average end-to-end delay and the average bandwidth, which means that the generated path can satisfy the QoS requirements. In addition, the protocol can also balance the energy of the sensor nodes to prolong the lifetime of the network.(2) An improved algorithm of LEACH is proposed in this paper to solve the problems of LEACH that cluster random election, uneven clustering, and the direct communication between nodes. Wireless sensor networks is divided into several areas based on the optimal number of cluster nodes in the new algorithm;when selecting cluster head nodes, the geometric location and residual energy of nodes are both considered in each area; in addition, nodes far away from the cluster head nodes transmit date through the intermediate nodes. Simulation results show that compared with LEACH, the new algorithm has better performance of network stability, and can prolong the lifetime of the network.(3) The collaboration localization algorithm based on weighted virtualforce for wireless sensor network is proposed in this paper to avoid the error accumulation occurred in AHLos algorithm. The new algorithm considers two cases:(1) In order to locate the unknown nodes which have no less than three neighbor anchor nodes, we use the atomic multilateration algorithm firstly, and then determin the positioning result. If the positioning result cannot meet the precision standard, we will use the weighted virtual force localization algorithm proposed in this paper, in which the unknown nodes move from the estimated position to the actual position gradually under the function of the virtual force by the anchor nodes.(2) In order to locate the unknown nodes which do not have enough neighbor anchor nodes for localization, the new algorithm utilizes the 1-hop anchor nodes collaboration with 2-hop anchor nodes. The simulation results show that the proposed algorithm has better performances of positioning accuracy and positioning rate than the AHLos algorithm.(4) This paper designs a localization system for mine tunnel. The design includes the system structure, the hardware and software of the nodes. Besides,in view of the long and narrow structure of the mine tunnel, this paper also proposes a simple deployment strategy based on redundant nodes, which can satisfy the requirement of the localization of the mobile nodes; then aiming at the situation that the positioning circles cannot intersect, we propose the range modified localization algorithm in which positioning circles are extended. The results of simulation in the corridor environment show that this system can realize the real-time monitoring about the environment, reliable transmission ofdata, as well as the precise localization of the workers who carry the mobile nodes.