Enhancement of Hierarchy Cluster-Tree Routing for Wireless Sensor Network

Xuxing Ding, Fangfang Xie, Qing Wu
2009 Computer and Information Science  
Many protocols such as clustering are proposed to minimize and balance energy consumption of the network because WSN (wireless sensor network) is energy-limited. In clustering protocols, CHs (cluster head) consume much more energy than its CMs (cluster member) which leads to the faster death of CHs. Many traditional protocols are designed to solve the problem, but they have some drawbacks respectively. In this paper, EHCT (enhancement of hierarchy cluster-tree routing for WSN) is proposed to
more » ... ther balance the energy consumption. The simulation results show that the performance of EHCT has an improvement of 41% over LEACH and 14% over UDACH in the area of 500m*500m, 28% over LEACH and 18% over UDACH in the area of 1000m*1000m. Keywords: WSN, Cluster-tree enhancement, EHCT LEACH-C (Heinzelman W., 2002, 4, pp.660-670) is an improvement of LEACH. In this protocol, CHs are not selected randomly but according to the residual energy. The node whose residual energy is more than the average energy of all nodes may be selected as a CH, so CHs can not die untimely. However, the deficiency of LEACH and LEACH-C is that the distribution of CHs is uneven and the data is transmitted by single hop. PEGASIS (Lindsey S., 2002, 3, pp.1-6) makes all nodes form a chain and specifies one node to communicate with BS directly. Each node only communicates with its neighbors and sends data to BS in turn, but it requires the location of all nodes. UDACH (Chen Jing etc., 2007, pp.628-632), a uniformly distributed adaptive clustering hierarchy routing protocol, enables that CHs are uniformly distributed, which balances the energy consumption and prolongs the lifetime of the network compared with LEACH and LEACH-C. But CHs in UDACH communicate with each other directly, when the Vol. 2, No. 4 Computer and Information Science 90 distance of two CHs is long, the sending CH consumes much energy. In this paper, EHCT is designed to further balance energy consumption and prolong lifetime of the network. It selects CHs based on a Master/Slave method. When a CH needs to send data, it selects a RN which is a member of the previous cluster to forward data to the next CH. The total distance of RN to previous CH and RN to next CH is minimum and less than the distance of previous CH to next CH. Wireless network model The sensor nodes are randomly distributed in a square area and monitor the environment unceasingly. We assume that all nodes are energy-limited. The location of each node is unknown and fixed. The BS is stationary and located far away from the monitored area. Each link is symmetric and the approximate distance of two nodes can be evaluated according to the received signal intensity. We use the energy model (HeinzelmanW., 2000, pp.83-86) to analyze the radio energy consumption ( Figure.1) . Two channel models are used in the energy model. One is free space model, the other is multi-path fading model. The distance between transmitter and receiver determines which model is used. d is transmitting distance of L-bit packet, multi-path fading model is selected when d is greater than d 0 , and the energy spent for the radio is 4 ( , ) * * (4) E f in equation (4) is the energy consumed by the node to fuse one bit. EHCT design An enhancement of hierarchy cluster-tree routing EHCT is proposed in this paper. It is an energy efficient clustering protocol which is divided into several rounds. Each round is composed of three phases: cluster formation, cluster-tree construction, data transmission. CHs are selected in cluster formation phase and aggregate the data collected from its CMs in data transmission phase. If the cluster-tree is constructed, CHs forward the aggregated data to BS. At the beginning of the network construction, BS broadcasts a HELLO packet to all the nodes at a certain power level. Each node can compute the approximate distance to BS according to the received signal intensity. Abstract Knowledge management (KM) become important for organization to take advantage on the information produced and can be brought to bear on present decision. Software maintenance (SM) is a process that requires lots of knowledge. Maintainers must know what changes should do to the software, where to do those changes and how those changes can affect other modules of the system. Knowledge management system (KMS) can support the processes of knowledge creation, storage or retrieval, transfer and application. KMS in SM could help the organization to make tacit knowledge into explicit and therefore decrease the dependency on employees' cognition. This paper is to apply KMS architecture in SM environment to overcome the problem faced by software maintainers during the software maintenance process.
doi:10.5539/cis.v2n4p89 fatcat:nhc7jiwirrhstorva4xsgky4pa