Research On Nodes Coopration In Energy-Effective Heterogeneous Wireless Sensor Networks

In recent years, progress in micro-electro-mechanism system (MEMS), digital signals process, wireless communications and computation has enabled the development of low-cost, self-organized, multi-functional wireless sensor nodes with short communication range. Compared with traditional networks, wireless sensor networks (WSN) have unqiue characteristics, such as rapid deployment, source constraint, multi-hop, dynamic topology, fault tolerance, data-centric and application-based. These features enable WSN to conduct many special applications, such as environmental surveillance, medical treatment, smart homing and military application.To enhance the performance of the whole network and extend network lifetime, ensuring its easy usage and the effectiveness of its data transmitssion is an important issue for wireless sensor network. This dissertation focuses on energy-efficient algorithms and protocols, including topology control algorithms, nodes collaboration, sleep-scheduling and so on.The main contributions of the thesis are as follows:The dissertation constructs a cooperated communication model between the clusters in frequency flat channel and frequency selective channel of WSN. And the model is analysed in detail. The capacity of fading channel between the clusters in WSN is proposed with expression of theory.Based on the topology of hierachical clusters, it analyses the further application of the virtual multiple-input multiple-output (VMIMO) systems in WSN. Considered selecting diversity and maximum ratio combining, a scheme is proposed to transmit data with the best channel in WSN. Space-time block coding is applied in cooporation nodes in transmitting cluster, and the maximum likelihood decoding is applied in cooperation nodes in receiving cluster. Compared with Chernoff bound, not only does the N_S algorithm put forward in this dissertation have the excellent performance in saving energy, but also has more precise function to describe the communication model between clusters. At the same time, neither does the algorithm reduce the total of transmitting data between clusters, nor increases energy consumption in circuit block. This algorithm quite suits to the situation with mass nodes as well as dynamic topology network. In the dissertation, considered the feature with heterogeneous nodes in WSN, it brings forward the whole communication scheme in network based on the model between clusters. Moreover, the conception of virtual head cluster is proposed, and WSN communication is divided into two stages. And the two stages are the communication in one cluster and between clusters. The energy consumption model is set up for different type nodes. Analyzed by theory and the simulation in matlab, the advantages of new scheme are proved in chapter 5.In order to prolong the lifetime of network and increase the throughput of efficient data in WSN, SEA (Sleep-scheduling&Energy-efficient Algorithm) is proposed in chapter 6, considering the characteristics with heterogeneous and redundancy in WSN. Compared with the correlation study, the SEA could effectively prolong the lifetime of network and increase data throughput after being proved by theory and simulation with matlab.A coverage model is proposed in chapter 7 based on the application with tracing object. Firstly, a concept of basic cell to localization is put forward using the principle of measuring distance with ultrasonic. Secondly, an excellent coverage model based on the basic cell in WSN is brought forward and analyzed in chapter 7.