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Research On Routing Techniques In Wireless Sensor Networks

Posted on:2010-09-10Degree:DoctorType:Dissertation
Country:ChinaCandidate:B C GongFull Text:PDF
GTID:1118360302981987Subject:Computer application technology
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Wireless sensor network (WSN) is a self-organizing network which is composed of a large number of low-cost, low-power tiny sensor nodes. These sensors can be used for monitoring, sensing, collecting the environment information in overlay area and transferring the processed data to users. WSN has many features including flexible deployment, good scalability, high reliability and low cost. It can be used in a wide range of potential applications, such as national security, environmental monitoring, disaster relief, and commerce applications, etc. Both academia and industry are very interested in it.Routing protocol takes charge of per hop transmission of data from sensors nodes to sink, which is one of key technologies of WSN and has significant impact on the network performance. Sensor nodes are operated by battery power, and have very limited computation ability, limited memory and limited bandwidth, which bring a tremendous challenge to design of routing protocols. Most existent and mature routing technologies are not suitable for WSN, and special routing protocols need to be designed for WSN. Based on systematically summarizing current routing protocols, this dissertation focuses on three basic and key routing technologies in WSN, namely, clustering routing, QoS routing and multicast routing. The major contributions of this dissertation are as below:1) Unequal Density-based Node Deployment and Clustering Routing ProtocolSensor nodes have limited and irreplaceable battery power, so how to efficiently use network energy is a question of the first importance for routing protocols in WSN. Clustering techniques can reduce energy consumption of nodes and increase the scalability of the network. Therefore, many efficient energy-aware clustering routing protocols are proposed, for example, LEACH, HEED, PEGASIS, and so on. However, there is the problem of the hot spots in the clustering protocols. When cluster heads corporately forward the data packet to sink with multi-hop communication, the cluster heads close to sink tend to die earlier because of heavy relay load from outer cluster heads, which results in the network being partitioned. The dissertation presents unequal density-based node deployment and clustering routing protocol (UDNDC). More nodes are deployed in regions with heavier relay load to provide enough energy for the inter-cluster data forwarding. The dissertation also analyzes the optimal node deployment density in different regions in theory. Simulation results show that UDNDC can effectively balance the energy depletion among network nodes and obviously prolong the network lifetime.2) QoS Routing Protocol based on Ant Colony Algorithm for WSNRecently, more and more applications in WSN are delay-sensitive, which need to get a continuous and real-time traffic from network, so QoS has to be considered. The objective of QoS routing protocols is to find the shortest path from source node to destination node, which satisfies QoS requirements including bandwidth, delay, jitter, packet loss rate, etc. Researches show that it is NP-hard problem to find a path satisfying two or more constraints. WSN has many characteristics, for example, low bandwidth, limited energy, poor processing capacity, frequent topology change, etc, which make it difficult to guarantee QoS in WSN. Ant colony algorithm has many advantages in solving complicated optimization problems. It has features including positive feedback, distributed computing and greedy heuristic search, which is very suitable for solving QoS routing in WSN. The dissertation presents an on-demand QoS routing protocol based on ant colony algorithm (ACQR), where forward ants are used to search a path from the source node to sink, and back ants are used to refresh the pheromone amount in the path. ACQR provides three routing services, namely, voice and video service, abnormal alarm service and ordinary information service. The dissertation designs proper state transition rule and pheromone updating rule for each service. Simulation results show that ACQR can ensure that the found path satisfies QoS requirements.3) Geographic Multicast Routing Protocol for WSNIn WSN, there exist many point-to-multipoint applications where multicast is an effective communication mode. Multicast can conserve network bandwidth and reduce energy consumption. Its core is to generate a multicast tree with minimal cost, namely, Steiner tree, which is NP-hard problem. Current heuristic algorithms have main disadvantages:(1) They need overall information of network which can not be gotten in large WSN; (2) Time complexity and space complexity are large, which make it difficult to realize routing protocol in common sensor nodes; (3) Path must be generated before transferring data, thus routing protocol has heavy communication overhead. The dissertation presents a geographic multicast routing protocol for WSN (GMRP), which is a hybrid of connection-oriented service and connectionless-oriented service, and uses GG (Gabriel Graph) algorithm to solve routing-hole problem. Its core is as follows. The source node sends probe packet which brings all destination addresses and data, and chooses path by a scoreboard algorithm. During the transmission of data, all intermediate nodes build routing table of multicast, and successive data packets follow the generated path in connection-oriented mode. GMRP does not need to build path before transferring data and has advantages of simple calculation and little overhead. Simulation results show that GMRP outperforms LGS and PBM in energy consumption, hop count and delay.This dissertation is supported by National Natural Science Foundation of China (No.60672137,90304018), Specialized Research Fund for the Doctoral Program of Higher Education of China (No.20060497015), Program for New Century Excellent Talents in University (No.NCET-08-0806), Opening Project of State Key Laboratory of Software Development Environment (No.SKLSDE-2009KF-2-02) and Key Project of Wuhan City, China (No.2004001001).
Keywords/Search Tags:wireless sensor network, routing protocol, clustering routing, QoS routing, multicast routing
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