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Routing Algorithm For Mobile Agents In Wireless Sensor Networks

Posted on:2008-11-08Degree:MasterType:Thesis
Country:ChinaCandidate:Z Y ZhangFull Text:PDF
GTID:2178360212495797Subject:Computer application technology
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With the progress in MEMS technology, wireless communications and digital electronic technologies, create a new information access and treatment technologies -- sensor networks. Sensor networks can be defined as constitution of a group of sensors to form self-organizing cable or wireless network. The purpose of sensor networks is to perceive, collection and processing of the object information that covered by network in the geographical regions perception cooperated, and disseminate the information to the observer.Wireless sensor networks (WSNs) is the kind of sensor networks in which information is transmitted wirelessly. WSNs has broad application prospects in many important areas, such as military and national defense, agriculture, urban management and bio-medical, environmental monitoring etc.Sensor Node is the basic of the composition of wireless sensor networks. Sensor nodes are generally composed of four parts: sensing unit, processing unit, transceiver unit, and power unit.A sensor network is composed of a large number of sensor nodes, which are densely deployed either inside the phenomenon or very close to it. The position of sensor nodes need not be engineered or pre-determined. This allows random deployment in inaccessible terrains or disaster relief operations. On the other hand, this also means that sensor network protocols and algorithms must possess self-organizing capabilities. Another unique feature of sensor networks is the cooperative effort of sensor nodes. Sensor nodes are fitted with an on-board processor. Instead of sending the raw data to the nodes responsible for the fusion, sensor nodes use their processing abilities to locally carry out simple computations and transmit only the required and partially processed data. The sensor nodes are usually scattered in a sensor field. Each of these scattered sensor nodes has the capabilities to collect data and route data back to the sink and the end users. Data are routed back to the end user by a multihop infrastructureless architecture through the sink. The sink may communicate with the task manager node via Internet or Satellite.The protocol stack used by the sink and all sensor nodes consists of the application layer, transport layer, network layer, data link layer, physical layer, power management plane, mobility management plane, and task management plane.Since the group as a new wireless self-organized network, wireless sensor networks have the following aspects distinctive features: Energy supply is limited; communications capability is limited; computational power is limited; high robustness and fault tolerance; strong network of highly dynamic and real-time requirements. These features require the solutions in the field of WSNs research to face several constraints: low energy consumption; energy is perceptive functions; robustness; low latency and scalability of nature.Regardless of the traditional network, or in wireless sensor networks, routing algorithms is the key support network transmission technology. Wireless sensor network routing algorithm is an important research direction. Existing algorithms can be divided into tow types: flat and hierarchical. The representative algorithms for flat are flooding and gossiping, SPIN, directed diffusion, SAR, etc. And for hierarchical are LEACH, TEEN, TTDD, multi- clustering, etc.Hairong Qi advanced the mobile-agent-basic distributed sensor networks (MADSN) in 2001, and elaborated using mobile agent in sensor networks has many advantages. Mobile Agent technology has already been used in wireless sensor networks for data collection and information fusion recently. In 2004, Qishi Wu etc. advanced the mobile agent routing problem (MARP), and proved that MARP is a NP-complete problem. Our work is aimed at the characteristics of wireless sensor networks basis on Qishi Wu's work and suggest three improvements, at last solved the MARP using genetic algorithms.We convert the problem parameters into the individuals made up of genes in the genetic domain. The code is a numerical encoding of the sensor (ID) label sequence L in the order of sensor nodes being visited by mobile agent. Our work sets initial populations of a systematic random sequence of sensor nodes ID. We presented the objective function based on energy consumption, path loss and energy signal. Then the fitness function of MARP is given to solve the problem. In our implementation, selection operator works based on the three copies Championship. We employ the Heuristic Crossover complete our crossover operator. System selects a gene randomly in a series of individual genes and makes mutation with 10% probability in this single point.In view of the characteristics of wireless sensor networks, our routing algorithm generated a specific number of sensor nodes randomly, ahead of choosing the rout. These nodes will be randomly scattered within the designated target area. Relationships amount nodes are stored as neighbor matrix, that the radius make estimate of. The matrix will be the basic of generate operator.Our work has improvement of the following three aspects, compare with the existing work:(1) Using one layer coding, so that coding sequence of all nodes can fully overcome the shortcomings of the information collection;(2) The connectivity between nodes is judged by information collected launch radius R, which is set first. This strategy has better adaptability;(3) Node location randomly generated by the system, which is closer to the real world in the sensor nodes scattering methodOur work has also carried out a number of simulation experiments on the basis of proposed the algorithm. Through the results of the experiment proved the effectiveness of the algorithm.
Keywords/Search Tags:Wireless sensor networks, Mobile agent, Routing problem, Generate algorithm
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