Research On The Range-free Localization Algorithm And Its Application In Environmental Monitoring In Wireless Sensor Networks

With the continuous progress of science and technology, the wireless sensortechnology rapid development, have been widely used in industry, agriculture,medical and military fields. Have it made an essential contribution to many areas. Thedevelopment of wireless sensor networks to today, is not just a single field ofknowledge, in the integration of science and technology in modern society, wirelesssensor networks with many other areas of knowledge are inextricably links such aswireless location, medical research, industrial and agricultural production and so on.In environmental monitoring, wireless network technology, more and more stronglywith the requirements of the people’s environmental supervision, environmentalmonitoring, the more, because also the application of wireless sensor networks inenvironmental monitoring the higher study of wireless sensor networks, not just thesensor networks and, more importantly, sensor networks, linkage can solve manyother problems in the field research and exploration of wireless sensor networks, sothat makes a lot more necessary. With the gradual increase of the people’senvironmental awareness and a growing sense of environmental monitoring,environmental monitoring is particularly important, but the majority of the naturalenvironment, the need for wireless sensor networks to be monitored through thedeployment of a large number of sensor nodes, Unlimited, the use of inter-nodecommunicate with each other, monitor the transmission of messages. Inside thewireless sensor network technology, the positioning algorithm is a very important part,but mostly based on the distance positioning algorithm using RSSI algorithm to locate.Ranging process of the algorithm is particularly susceptible to externalelectromagnetic environment, multipath propagation and other factors, the samedistance from the signal strength attenuation in the dissemination of different degrees, resulting in large errors, the positioning is not ideal, so this a distance-independentlocalization algorithm-CDLIE algorithm, this algorithm is to reduce the impact ofthe nodes affected by environmental factors, to improve positioning accuracy, reducecommunication overhead, but also reduce the cost. In this paper, the comparativestudy of several commonly used positioning algorithm selected two typical algorithms:centroid algorithm and DV-Hop algorithm to focus on. And combinations of these twoalgorithms, the advantages of these two algorithms to compensate for each other’sshortcomings, from the whole CDLIE algorithm to improve CDLIE algorithm by theunknown node based on the anticipation value t choose to use the centroid algorithm,or DV-hop algorithm, the centroid algorithm communication overhead is relativelylow, such a choice usually achieve positioning accuracy; Otherwise, select theDV-hop algorithm, because the DV-Hop algorithm for high positioning accuracy, butalso easy to implement, but the communication overhead is relatively high. Were alsoconfront the heart algorithms and DV-hop algorithm has been improved, to improvepositioning accuracy and reduce the communication overhead. So that the monitoringnodes to reduce the impact by environmental factors the CDLIE algorithm, it is moresuitable for applications in environmental monitoring. Algorithm experimentallyverified and compared with the DV-hop algorithm proved CDLIE algorithm improvesthe positioning accuracy of3.2%-6.1%, and confronted by node heart algorithms andDV-hop algorithm select the number to come to the conclusion of the communicationoverhead is also reduced. Further proof CDLIE algorithm is suitable for application inenvironmental monitoring for wireless sensor networks.