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Research On Data Collecting Strategy In Physical Location Limitied WSN-MS

Posted on:2016-09-16Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y S JiangFull Text:PDF
GTID:1108330479485484Subject:Control theory and control engineering
Abstract/Summary:PDF Full Text Request
In wireless sensor network(WSN), the sensor nodes that are close to the sink have to retransmit huge amounts of data for other sensor nodes. Those nodes will fail earlier than others because the rapid energy consumption, and shorting the lifetime of network. This is called as “hotspots problem”. One method to prolong the lifetime of network is to use sink mobility. Wireless sensor network with mobile sink(WSN-MS) makes the sensor nodes can take turns to become the neighbors of the sink due to the sink mobility. So, the energy is consumed evenly among the sensor nodes, the hotspots problem is mitigated and the lifetime of the entire network can be prolonged. On the other hand, in some scenarios, the limitations of environment, devices or the funds for devices bring challenges to deploy positioning equipment. It is difficult to get the physical location information of nodes. Thus, a data collecting strategy that doesn’t depend on geographical position information is needed.Sink status update, routing protocol and path planning, which are three aspects of the process of data collection in WSN-MS, are studied in this article without the physical locations of nodes are unknown. Some breakthroughs on research methods and ideas are sought during the research. The main research work and achievements are stated as follows.① When the physical locations of nodes are unknown, a backbone formulation algorithm, which is based on pursuit algorithm, is proposed to complete the sink status update, establishment and maintenance of routing after sink moved. Those actions are limited in the backbone that includes a small number of nodes, and therefore reducing the overhead of corresponding communications. In the proposed algorithm, a dominating set and action sets of dominate nodes are got. Then, executing the pursuit algorithm, in which nodes are treated as learning automata and its action probability vector is optimized iteratively. Finally, an approximate solution of the minimum connected dominating set is got as backbone. It is also shown that the algorithm is ε-optimality with the changing speed of learning parameter. The simulation results show that, comparing with other algorithms, our algorithm reduces the size of backbone network within a reasonable message overhead, and it has lower average node degree.② The broadcasting protocol of sink status update after sink moved for the scenario, in which failed nodes occurs and the physical locations of nodes are unknown, has been studied and the extended directional dominant pruning(EDDP) is proposed. In EDDP, a virtual coordinate is attached to each node based on greedy embedding. According to those virtual coordinates, the directional neighbor set is proposed to reduce the number of nodes that need to be covered by the forward list, and resulting in the reduction of the redundant transmissions. The assisted forward nodes are chose to ensure that EDDP adjust the failures of nodes. The extended directional total dominant pruning algorithm and the extended directional partial dominant pruning algorithm are proposed to reduce more redundant transmissions based on the neighbor information that a node could get. The simplified marked/unmarked termination criterion is proposed to remove the query messages of marked/unmarked termination criterion. And it just has a little performance losses compared with the marked/unmarked criterion that not considers the influences of the query message and reply message. Simulation results show that our algorithms outperform their reference algorithms in terms of the average number of forward nodes, average number of packets received by a node and number of collisions.③ The fast reconstruction of routing strategy after sink moved for the scenario, in which failed nodes occurs and the physical locations of nodes are unknown, also has been studied. Virtual-node greedy embedding(VGE) is proposed, and a novel routing algorithm is proposed based on VGE. VGE gives each node a virtual coordinate that makes a greedy path is existed in any two nodes in the network. It guarantees the greedy forwarding of the packets from sensor nodes to the sink when there is no failed node in WSN. VGE keeps the greedy property when new nodes join the network after the initial embedding and does not change the coordinates assigned previously. Based on the characteristic of embedding process, modified gravity-pressures(MGP) algorithm is proposed to find a routing path quickly when there are some failed nodes in WSN. Furthermore, particular solutions of the parameters in VGE are presented with concise style. Comparing with other virtual coordinate based algorithms, no matter there are some obstacles or failed nodes in the network, our algorithm performs well and has a smaller path stretch, which means the hops of communication are smaller and therefore less energy consumptions.④ Focusing on the delay tolerant network that includes a single mobile sink and the length of sink’s tour is bounded by a pre-determined constraint, a strategy for tour planning of mobile sink is proposed without the physical locations of nodes. The main goal of this strategy is to get a tour with minimum total hops of data transmission. And, in the process of formation of tour, the selections of data caching nodes are also considered. Based on the cross entropy method, our strategy optimizes the sampling probability matrix in order make the choice of the next tour node has a large probability to get a better tour. Compared to the mobile sink path constriction strategies that based on cluster partition or spanning tree, our strategy does not require a special structure. It is more flexible and expands the solution space to make the strategy has a chance to get better results. On the other hand, a probabilistic data forwarding policy is introduced to makes the power consumptions of those nodes, which have the same hops to the tour, are balanced. Simulation results show that our strategy outperforms the traditional method in terms of the lifetime of wireless sensor network and makes the power consumption of data catching nodes are more balanced.
Keywords/Search Tags:WSN, Mobile sink, Broadcasting algorithm, Routing protocol, Path planning
PDF Full Text Request
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