Research On Hierarchical Routing Algorithms For Wireless Sensor Networks

Wireless sensor network (WSN) is a self-organized network constituting sensor nodesand base station. Sensor nodes are responsible for sensing and processing the information inthe monitored region, and then they cooperatively transmit the collected information to thebase station by wireless communication. They are usually powered by batteries, and never tobe supplied energy after deployed. So, energy efficiency is the core issue in the research forWSN. The limited energy restricts sensor nodes’ capacity for storage, procession, andcommunication. Hierarchical routing protocols based on clustering are more suitable forwireless sensor networks compared with plane routing protocols to improve energy efficiencyeffectively. Thus, this paper conducts an in-depth research on hierarchical routing algorithmsfor wireless sensor networks. The main works and innovations of this paper can besummarized as follows:First, above all, this paper makes in-depth research and systematic summarization onthe architecture of WSN, the key technologies involved in WSN and the situation of WSN’sactual application. Then, this paper summarizes the goal for designing routing protocols forWSN, studies the strategies for saving energy, classifies the existing routing protocolsproposed for WSN, analyses the classical routing protocols proposed for WSN in detail, andmakes an in-depth analysis of the advantages of hierarchical routing protocol.Second, against the shortage existing in the conventional hierarchical routing protocolproposed for conventional heterogeneous wireless sensor network, this paper proposes EDU(Unequal Clustering Algorithm Based on Energy Distribution) algorithm. EDU algorithmdraws on the method of calculating the parameter for competing cluster-heads proposed inEDBUA algorithm. EDU algorithm has the following innovations: first, EDU lets the sensornodes near the base station and satisfying certain conditions communicate with base stationdirectly. This measure can save energy with a certain degree. Secondly, sensor nodes calculatethe radius of competing cluster-head on the basis of their distance from them to base station.Then, non-uniform clusters are constructed in the network. This measure can weaken theeffect of “hot spot”. Moreover, the cluster-members select the appropriate cluster-head to joinin on the basis of cluster-heads’ residual energy, distance to base station and cost for communication rather than on the basis of the strength of the received signals. Finally, whenthe cluster-heads which communicate with base station by multi-hop data transmission selectrelay node, they consider candidate nodes’ residual energy, distance to base station and cost forcommunication comprehensively.Third, this paper proposes adaptive and hierarchical routing algorithm EDA(Energy-based and Distance-based Adaptive Clustering Algorithm) for wireless sensornetworks on the basis of energy and distance. EDA algorithm improves the previoushierarchical routing algorithm in the following three aspects: the competition for cluster-head,the calculation for the radius of clusters, and the construction for routing tree among clusters.EDA algorithm introduces probability model basing on energy and distance to generatecandidate cluster-heads. This measure reduces the number of the nodes competing forcluster-head and the information packets used for exchanging information in the network, andsaves energy. EDA algorithm sets timer on the basis of residual energy, so that the candidatecluster-head with the most residual energy in the local area becomes cluster-head. Thismeasure can reasonably control the distribution of cluster-heads. When EDA algorithmcalculates the radius of competing for cluster-head, it not only considers candidatecluster-heads’ location, but also considers their residual energy. This measure can effectivelybalance network’s load. EDA algorithm calculates the optimal forwarding hops on the basis ofthe distance from cluster-head to base station, and then cluster-heads select the optimal relaynode by combining the information of residual energy and communication cost.Fourth, this paper builds a simulation environment on OMNET++platform. Under thesame simulation environment, this paper achieves the simulation experiments for EDUalgorithm, DEEC and EDBCA which have been proposed for heterogeneous wireless sensornetwork. The experiments’ results show that EDU algorithm can effectively balance the loadof network and extend network’s life cycle compared with DEEC and EDBCA. This paperalso achieves the simulation experiments for EDA, I-LEACH, and DEBCA under the samesimulation environment. The results of experiments show that, compared with I-LEACH andDEBUC, EDA algorithm has better stability, and can better balance energy consumption in thenetwork, improve energy efficiency, and extend the network’s life cycle.