Research And Design Of RSSI Localization System Based On Core In Wiseless Sensor Network

With the development of technology of electric manufacture and integrity, the bodies of wireless devices become smaller, the performance become stronger, and the area of application become wider. Composed of small wireless devices, Wireless Sensor Network (WSN) plays more important role in life and manufacture, such as environment detecting, animal tracker and so on. People also need WSN to provide more kinds of performance, such as wider bandwidth, safer message routing, more time service, more long service time etc. But many of them need some basic information as supports, among them, location is especially important.The application of WSN needs the location of nodes in many aspects. In some case, the location of nodes is the key factor which decides the value of the message, and also necessary factor for finishing the next function, such as message routing.It is very important that how to compute the location of nodes, but the nodes of wireless sensor network are limited by its resource, such as low compute level, little memory size, short communication distance, short power life and so on, all these limit the selection of localization technology and localization algorithm. Currently there are many localization systems, most are in the term of testing or mode proposing, few are put into use. The main reasons are the tolerance of the technologies of ranging, the difficulties of realization and also include the complexness, the heavy workload and the high communication load.This paper analyzes the technologies of ranging, the algorithm of localization and their shortcoming and advantage. It focuses on the principle of RSSI localization which can be put into use now and the relevant chip CC2431. Base on these, it proposes a new localization system—RSSI Localization based on Core, which introduce a new special structure—Core. Just like crystal procedure, crystal core is first formed, growing around core, crystal is finally formed. We hope core play a framework role and locate other nodes or cores, and also are located by others, finally all nodes are located and whole network become order. The core of this system is composed of three sensors, which are placed on the three vertexes of triangle. The length of lateral range from 3m to 6m, the length of lateral of mobile core is limited by the environment, but the lateral of static core can design more long to get more precise. Three nodes of the core are connected directly by wire to deduce the communication load. In the design of the node and core, MCU—ATmega128 is used as task process center.Through simulation, it was found that the system with core could actually improve on precise, accuracy and stability of localization.Finally, the paper gives the design of system, how to design the node is subject of this part.