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Research On Query-Based Routing Protocols For Wireless Sensor Networks

Posted on:2012-06-05Degree:MasterType:Thesis
Country:ChinaCandidate:Z Y CaoFull Text:PDF
GTID:2178330332467393Subject:Computer system architecture
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With the advancement of wireless communications and microelectronics, wireless sensor network (WSN) has been developing rapidly in recent years. WSNs are utilized for military reconnaissance, environmental monitoring and surveillance, disaster prevention, health care, traffic management, industry, agriculture, scientific research, space exploration and other applications. As one of the core technologies, WSN routing technology has become a focus of research.WSN is always composed of a large of small sensor nodes, and the nodes are usually deployed densely inside or very close to the phenomenon. In order to complete the assigned tasks, nodes sense, collect and transfer the information of the search coverage mutually.Routing technology plays an important role in WSN. The design of WSN routing protocols is complex and difficult which poses a challenge for the designers, because sensor nodes have limited resources in power, computing capability, memory space, and WSN is based on local topology and the topology changes frequently, and WSN has characteristics of data-centric, application-oriented.There are several routing protocols used in query-based applications, but some typical ones have a heavy routing overhead. Directed Diffusion (DD) will have a great consumption in gradient field establishment phase, and the overhead will lead WSN to poor performance, especially in the case of topology changing frequently. Rumor Routing (RR) protocol which selecting next hop randomly will avoid the heavy overhead of gradient field establishment phase in DD, but the random forwarding will result in additional delay, even routing loop.A modified Tree Routing (TR) protocol has been used in 6LoWPAN to meet query-based applications. TR will have a low routing overhead, moreover it cannot cause routing loop. Unfortunately, TR can result in excessive consumption of nodes at the critical locations, which will decrease the integrity and lifetime of networks. In order to solve the above problems, Sink Routing Table (SRT) protocol is proposed in this paper. SRT protocol includes network-setup phase and data-transfer phase. In network-setup phase, to build a hops field, each node learns the hops count from Sink through exchanging messages between neighbors. Node sets the neighbor node with the minimum hops count from Sink as its optimal neighbor and reports the information to Sink who records it in Sink Routing Table. In data-transfer phase, hops field routes the packets from a internal node to Sink and Sink Routing Table routes the packets from Sink to a internal node. SRT involves in energy awareness strategy to reduce the load on nodes with low energy, and thus prolong the lifetime of the nodes at the critical position. Accordingly the integrity and lifetime of networks can be improved.With the purpose of verifying the performance of SRT, I designed and implemented it in NS2 (Network Simulator version 2). Then run the simulation scripts in some different scenarios, and compare the results to TR protocol. According to the comparison results, we can conclude that SRT protocol can significantly enlarge lifetime of WSN with regularly distributed nodes. Furthermore, SRT can provide an efficient routing and prolong the lifetime of WSN with randomized distributed nodes, especially in large density nodes scenarios.Above all, SRT protocol not only maintains a low overhead in packets routing, but also provides good integrity and lifetime for query-based WSN applications.
Keywords/Search Tags:WSN, Routing protocols, Sink Routing Table, network simulate, NS2
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