Research And Implementation In Simulation-Supporting Technology Of Wireless Sensor Network

As akindofwide-appliedcross-knowledgetechnology,Wireless SensorNetwork(WSN)is a kind of self-organized, distribute processing and fast developing Ad-hoc network. InWSN, the monitoring and managing of target area is carried out through deploying largeamount of wireless sensor nodes in that area. Obviously, it is necessary to make sure of nodepositions to implement node locating and chasing. Divided into two categories, Range-BasedMethodandRange-FreeMethod,positioningtechnologyis oneofthemajorresearch subjectsinWSN.AsaRange-BasedMethod,MDS-MAPcalculates nodepositions from multi-scalingmethod. Owing to the usually unacceptable expense in putting through the research in realWSNenvironment,WSN-relatedtechnologies arecarryingout inNS2(NetworkSimulator2)nowadays. NS2 is a flexible in operating, high efficient and source-open scalable networksimulating platform, with many advantages, such as shortened developing period,Object-Oriented(OO)supportiveandvisualizationofbothprocessandresultofexperiment.In this paper, simulating WSN-relative technologies in NS2 is introduced. From therelation between communication range and signal intension among nodes, NS2communicating range reconfiguration is realized through source code modifying. There areexpatiating on both theory and practice on RSSI distance calculating method and distancebroadcasting. In WSN, non-definite nodes should collect their distance information in range.Then, this information is passed onto nodes with stronger processing abilities. The positionsare calculated in sink node at last. So, flood broadcasting method in surface is devised in thispaper,tosimulatingtheinformationgatheringofwholenetworkinsinknode.Research on definite constraint locating method is at the end of this paper, expatiatingtheory and practice on classic MDS locating method, MDS-MAP locating method andMDS-MAP (p) locating method. Specially, MDS-MAP includes four major steps. First,referring to distance information among nodes, calculate the length of shortest paths betweennodes and generating the adjacency matrix which stores the estimated distances of all nodepairs. Second, through multi-scaling method, transform the estimated distances into relativecoordinates. Third, generate the perfect function form by which all coordinates relative toreferring nodes, positions of secure nodes and Least Squares Minimization many be put intowell use. Fourth, and the last, using the perfect function form on coordinate transforming,transform all relative coordinates into absolute ones. As a kind of distribute locating method,MDS-MAP (p) divides the whole network into several small local ones, called sub-diagram.MDS-MAP,akindofcentral processingmethod,is manipulatedineachsub-diagram,helping generaterelativecoordinates. Thesub-diagrams areput intoawholeinagivensequence.Themergingofsub-diagrams isalsoexpatiatedinthispaper,theoryandpractice.Errorinmergingof sub-diagrams may be brought down by increasing the amount of common nodes betweensub-diagramsandadaptingtherightsequence.There is a simulation experiment and analyze to the result at last. First, the ranging andbroadcasting method is implemented. In this method, through broadcasting all the distancesmeasured by nodes, sink node gets all the ranging information in the WSN. Then, locatingnodes with MDS-MAP Locating Method is carried out, with the calculated results comparedwiththeactualpositionsofnodesandexperimentresultanalyzed.