Research On Energy-efficient Routing Protocols In Wireless Sensor Networks

Wireless sensor networks consist of large amounts of tiny sensor nodes, which are equipped with components for sensing, data processing, and communicating. As a new method of information acquisition and processing, wireless sensor networks can be applied to many fields such as military surveillance, environment monitoring, medical treatment, etc, and thereby have been popular in information science and technology research.Since the sensor nodes are power-constrained, energy efficient protocols need to be designed to prolong the lifetime of networks. Cluster-based routing protocols meet the requirements of data-based routing, especially for large scale sensor networks with better performance in scalability and energy efficiency than flat routing protocols, which makes them the major routing protocols for wireless sensor networks.Based on systematic analysis of relative works on cluster-based routing protocols, this dissertation focuses on cluster head selection mechanism and low energy data transmission in cluster-based routing protocols. The major work can be divided into the following four chapters:1. In view of the problem that the number of cluster heads produced by the classical protocol LEACH in each round doesn't distribute in a reasonable range around the optimal value, an improved clustering algorithm (CONCH) based on optimal number of cluster heads is proposed. The number of cluster heads generated by CONCH in each round is exactly the optimal value and the cluster heads distribute near uniformly in the network. Therefore, CONCH can decrease the energy depletion of the whole network and perform well on energy balance.2. To overcome the shortcoming of the voting-based clustering algorithm (VCA), a two selection mechanism based clustering algorithm (TSMC) is proposed. TSMC combines the voting with the time-driven clustering mechanism in cluster head selection. First, the model of multiple attributes voting is presented, and the weight of the multiple attributes is calculated by using entropy weighting method. Then, a converting function is designed to map the vote into a certain length of waiting time for cluster head competition. TSMC can balance the energy load of sensor nodes as well as reduce information overhead, and thus prolongs the network lifetime.3. A fuzzy multiple criteria decision making based clustering algorithm (FMCDM) is proposed, in which the cluster heads selection is based on fuzzy sets theory. In FMCDM multiple attributes of a node are considered for cluster heads selection and the information overhead in algorithms based on voting is avoided. The FMCDM algorithm has good performance on energy efficiency and energy balance for the network.4. In view of the fact that the initial energy of sensor nodes varies random in a certain range in multilevel energy heterogeneous wireless sensor networks, a fuzzy low-energy node protection clustering algorithm (FLENP) is proposed. In FLENP, sensor nodes situating at the area with lower energy have more chances to act as cluster head nodes. Low-energy nodes are protected to balance the energy load in the network, and hence the lifetime of network is prolonged.