Research On WSN Iterative Localization Algorithm Based On Distance Gonstraint

In recent years, along with advance of microelectronics technology and wirelesscommunication technology, wireless sensor network technology which has the characteristicsof low power consumption and low cost has been booming. Especially with the advent of theInternet of things technology, which plays an important role in the three layer networkstructure of the Internet of things for perceiving information, wireless sensor networktechnology has more highly attention of researchers both at home and abroad. Nowadays,wireless sensor network technology has been widely used in many fields of people lives,suchas intelligent household, environmental monitoring, medical service and so on. As one of thesupporting technologies in wireless sensor networks, node location technology is also a veryimportant research direction.The location information is a very improtant part of the information which wirelesssensor network monitor in monitoring area.It’s no sense if there is no location information ofmonitoring data for users. Therefore,whether can obtain the target location in the monitoringarea accurately becomes a key research direction in the study of wireless sensor networktechnology.According to the different evaluation conditions, the localization algorithm of wirelesssensor network can be classified. Nowadays, the commonly used classification will be dividedinto the following two kinds: the positioning algorithm based on distance (range-based) andthe localization algorithm has nothing to do with the distance (range-free). Positioningalgorithm based on distance has higher precision, but the cost of hardware conditions requiredis high, and it’s not suitable for most of the practical application. And range-free localizationalgorithm has the advantage of no need the hardware to measure the actual distance betweenthe nodes, only needs to use network connectivity to estimate the distance informationbetween the nodes, and thus to estimate the location. This algorithm has low hardwarerequirements, cost savings, be suitable for most practical applications, but the positioningprecision will decline. Two types of localization algorithm both have advantages anddisadvantages, be applicable to different application fields respectively. Therefore, design aimproved localization algorithm which is combined with two kinds of localization algorithmis a new research trend nowadays. Under the trend of the research, this article analyzes the two types of localization algorithm and the Hop–terrain localization algorithm which is atypical improved algorithm combining range based with range free algorithm. And then wedesign a new decision iterative localization algorithm based on distance constraints. Thisarticle’s main innovation work is as follows:1. According to the localization algorithm principle and positioning process, I analyzedthe Hop-terrain, and validated the positioning performance through the simulationexperiments. In nodes initial position estimation stage of Hop-terrain localization algorithm,we find it could lead to the different nodes which are close in location or on the edge of thenetwork choose the same shortest path at the same time, and get the same locationinformation through the trilateration localization algorithm due to the use of range-freeDV-Hop localization algorithm, this is unreasonable clearly. In order to solve this problem,this article adds a random position deviation caused by random noise in the node initialposition estimation stage. In this process, each node increases a small random noise on theinitial count coordinates through the DV-Hop localization algorithm, then produces a smallposition deviation. This is a reasonable solution to slove various nodes have the same initialestimate location.2. Through the research and analysis of the Hop-terrain localization algorithm simulation,we find when the connectivity of the network is low, the iterative process of successfullocalization node rate is very low. In order to solve this problem, this paper makes thefollowing improvements: In the node coordinates iterative update stage, this article introducesthe concept of credibility weight and node identifier, and has carried on distance constraintsdetermine to the nodes which are positioned successfully by trilateration localizationalgorithm with weighted values, at the same time we have a choice of selecting correspondingiterative result to update their location coordinates, so that each node’s location willconvergence to the true location of the node continuously, improving the proportion ofsuccessful localization node effectively under the condition of low network connectivity. Atthe same time, we update the credibility weights of the ordinary nodes after each iteration,neighbors node positioning credibility increases because of its position is more and moreconvergence, then the credibility weights of the ordinary node will also increase gradually,improving the overall positioning accuracy of the algorithm in further. At last, we prove thispoint by simulation analysis comparing with Hop-terrain localization algorithm.