| Wireless sensor networks (WSN), which is constituted by a large number of randomly distributed micro nodes with a self-organization way, including the integrated sensor unit, the data processing unit and the communication unit.In view of the multi-hop transmission characteristics of the wireless sensor network, there is obvious difference in the routing protocols design with existing communications networks, especially in the case that the entire network nodes are disposable sown and the node energy is non-renewable. Therefore, improving the energy consumption of the balance the network and prolonging the network life cycle became the primary goal for wireless sensor networks design. Presently, the cluster-based routing protocols is the core of the wireless sensor network routing protocol, and the multistage cluster tree topology structure, as the foundation of the cluster-based routing protocols, had become a research hotspot in wireless sensor networks due to its low energy consumption and long life characteristics in recent years.A new algorithm, called ETBG (energy-aware topology control protocol based on gradient) was introduced in this paper. In this algorithm, the network was divided into a plurality of semi-circular gradient field according to the base station, and the nodes was combined together to form cluster tree based on the value of the weights between nodes and the gradient grade composition. Smaller delay was the advantage of this algorithm, but the weakness that energy loss increased with increasing distance between parts of the nodes was obvious, too. Because the weight in the algorithm was single and the energy consumption of the nodes in long distance data transmission was out of considering.To solve this problem, a hierarchical clustering algorithm based on the gradient with a gateway had been proposed in this paper. A regulator was set in node clustering to adjust the residual energy and the distance of the nodes, ensuring the node with high comprehensive weight value to be the cluster head node. Meanwhile, the members of each cluster head had been optimized based on load balancing. Finally the gateway was added to the cluster head to established cluster tree according gradient grade.So the disadvantages of the ETBG that energy loss increased severely with increasing distance between cluster head nodes was avoided, and the number of network cluster head was reduced. Meanwhile, the network life cycle was prolonged due to the cluster head rotation strategy. In addition, the local maintenance and updating strategy of the algorithm was proposed,so that the nodes could establish a connection with each other rapidly when the local topology was changed, which ensured the normal operation of the network and improved the adaptively of the algorithm. |
