Research On The Key Technologies Of Energy-Efficient Clustering Routing Algorithm For Wireless Sensor Networks

With the continuous development in microelectronics technology and wirelesscommunication technology, wireless sensor network (WSN) as the core technology ofthe Internet of Things has flourished in recent years. As the sensor nodes in WSN aregenerally battery-powered, how to save their energy consumption and prolong the lifetime ofWSN are the main challenges. Domestic and foreign scholars have done a lot of researchwork on this issue, which has proved that the topology and routing algorithm optimization ofWSN is important for prolonged survival time of wireless networks. In flat routing, the status and sensor capabilities of each sensor node in WSN are of equalimportance, and the sensor node must store routing table, through which the node can transmitdata to the other node. Therefore, the flat routing algorithm is more suitable for small-scalenetworks and networks with less sensor nodes. Compared with the flat routing algorithm, theclustering routing algorithm is more in line with the needs of data-based routing algorithm byselecting cluster head and forming clusters to exchange information. Moreover, the clusteringrouting algorithm can effectively manage nodes and data, which means better robustness andextendibility, and therefore are more applicable to large-scale WSN with plenty of sensornodes. The thesis researches on single-hierarchical routing algorithm, multi-hierarchicalrouting algorithm and the methods of avoiding the energy hole in WSN. The main contentand innovation of the thesis are as follows:(1) The thesis analyzes classical single-hierarchical clustering routing algorithmLEACH and LEACH-type in detail. In these algorithms, there are some shortcomings. Forexample, the number of clusters in LEACH is not fixed, the process of selecting CH isoptional and the selected CH is unreasonable. In order to solve these problems, the thesisproposes Minimum Distance Clustering Algorithm based on an improved DifferentialEvolution (MD-IDE). Firstly, MD-IDE determines optimal number based on theoreticalanalysis of the energy consumption in WSN, MD-IDE which combines the advantage ofSimulated Annealing and Differential Evolution can select the appropriate CHs in that theselecting process of CHs is more elaborate and scientific, and the distribution of CHs ismore reasonable. Secondly, the thesis compares the performance of MD-IDE, MD-DE, LEACH, and LEACH-C. The results of simulation show that MD-IDE has better performance than the other routing algorithms in the aspect of prolonging network lifetime and reducing communication distance of nodes.(2) Multi-hierarchical clustering routing algorithm can overcome the shortcoming of singer-layer clustering routing which has strict restraints on communication distance between nodes. This thesis proposes multi-hierarchical clustering routing algorithm based on improved differential evolution (MHCR-IDE) routing algorithm. MHCR-IDE firstly needs reasonable hierarchical division and the CH number of each layer. In each layer of WSN, the algorithm selects the appropriate nodes as cluster head and forms the clusters based on improved differential evolution (IDE). Once the establishment of cluster is finished, the data of outer layer CH must be forwarded to inner layer CH and finally to the Sink. The data of node can multi-hop or single-hop to the CH in one cluster. The Data transmission mode of MHCR-IDE can greatly reduce the restraints on communication distance between nodes and increase the applicability of the algorithm. Compared with the Multihop-LEACH routing algorithm, this algorithm has obvious advantages over Multihop-LEACH in the aspects of reducing the communication distance of WSN, saving the energy consumption and prolonging the network lifetime.(3) The problem of energy hole in MHCR or Multiple hops routing algorithm was discussed along with how to mitigate the problem in the thesis. Theory analysis and simulation show the energy hole of WSN can be mitigated or eliminated with uneven layered method and node sleeping-scheme in certain conditions. The thesis proposes energy hole avoidance algorithm based on node sleeping and uneven layers (EHAA-NSUL). In the first phase of EHAAE-NSUL, the nodes in WSN are uneven layered so that the total energy of inner layer is more than that of outer layer, then the sensor nodes in each layer are divided into the sleep nodes and the work nodes according to the remaining energy of nodes in the second phase. After that, the appropriate CHs of each layer can be selected through IDE algorithm so that the cluster can be formed and network topology of WSN can be finished. At last, the obvious effectiveness of mitigating energy hole in EHAA-NSUL was validated through amass of simulations.(4) With the maturity of wireless sensor network technology, in practice, wireless sensor network technology can be more easily integrated with other technologies such as speech recognition, image acquisition, which can greatly extend the range of applications of WSN. In this thesis, two self-developed systems (JPEG image transmission system based on ZigBee and remote control system based on speech recognition) are introduced. The development process and design methods which obtained from the two systems are analyzed in detail. The cluster routing algorithms, development process and design methods of WSN in the thesis can provide a solid foundation for the design of complex WSN systems.