Wireless Sensor Networks, Hierarchical Routing Technology Based On Energy Control

With the rapid development of communication techniques, embedded techniques and sensor techniques, wireless sensor networks (WSNs) gradually attract people's attention. Sensor nodes in the wireless sensor networks communicate with one another through single hop or multi-hop communication and assume function as routers. Each node not only carries out its tasks such as sensing and transmitting data, but also discovers and maintains routes and constructs the network architecture. Routing technique, therefore, is a key point in WSNs. Because of WSN's feature of energy constraint, routing technique is aiming on how to decrease and balance the sensor nodes'energy consumption and how to maximize the lifetime of networks.Compared to flat routing algorithms, hierarchical routing algorithms are more advantageous. First, LEACH and LEACH-C algorithms are introduced and simulated. LEACH-C is a centralized clustering routing algorithm, in which the coordinates and current energy information of all sensor nodes in the network are gathered in Base Station (BS) node. LEACH is a distributed clustering routing algorithm which differs from LEACH-C. The simulation data is then analyzed and final result demonstrates that LEACH-C is more efficient than LEACH.Many of the common clustering algorithms are based on the selection of cluster-head nodes and the formation of clusters in LEACH, and there's a few based on the control operation against energy consumption during data transmitting in LEACH-C. And then, an improvement of LEACH-C based on nodes'energy is proposed which aims to increase the lifetime of the networks by choosing the temporary cluster-head nodes and looking for the intermediate nodes in the same clusters which refers that member nodes communicate with the cluster-head nodes through multi-hop communication, to transfer and balance the nodes'energy consumption and information overload among all of nodes in the network. Improved algorithm is described in detail and its working flow chart is given. Also, the algorithm is simulated under several situations. The simulation results are analyzed, which prove that the lifetime of the network is prolonged. One of the most distinguished features of WSNs is data centric. In LEACH-C algorithm sensor nodes send data periodically to BS, which is applicable in applications of sending data continuously like environmental monitoring. But sometimes single or continuous data query is needed. LEACH-C is a centralized algorithm, so the network can respond quickly to user's query request through the network information stored in BS. And then, a data query scheme is proposed based on clustered architecture formed by LEACH-C algorithm and simulated finally by applying it to LEACH-C and clustering routing algorithm proposed in the paper.