Research On Positioning And Tracking Technology Of Wireless Sensor Networks And The Corresponding Security Strategy

The development of micro-sensor technology, the micro-electronic technology, the wireless communication as well as the computation technology, largely facilitate the progress of the WSN (Wireless Sensor Network) which integrates the collection, handling and wireless-transmission of information. With the further research work about the WSN, its application range becomes more and more extensive.The WSN is composed of wireless sensor nodes which are able to sense, calculate and communicate. Among the research works on its various applications, the node position is the primary supporting technology about the application of the WSN, and the premise to realize the many other applications of WSN. For many years, there have been many professionals and research institutes that have carried on works in-depth aimed at view of the WSN characteristic:energy limited, low cost, self-organization, wireless correspondence, multi-jumped relaying, distributional processing, fault-tolerant and so on, and have brought forward numerous positioning algorithms. In this paper, we summarized the positioning technology of the WSN, and focused on3aspects:the security position, the position of the static nodes and the tracking of the mobile nodes. We also explored its practical application and made some achievements.(1)In view of the miniature and subminiature trend in the development of the wireless sensors, we designed a new type of printed antenna with a coplane wave-guide feedback structure,2.4GHzs, adopting a monolayered substrate, and carring on the feed-back through the CPW line. The simulation result from the special software indicated that this antenna can obtain good impedance matching in a rather wide frequency range, high gains, isotropism, compactness, being easy to manufacture, low cost and&.(2) In view of that RSSI often gets large errors in ranging and is liable to interference, we proposed a new Gauss fit location algorithm(GFL) in order to improve the ranging precision and stability of the RSSI from experiments in a large area on a self-made experimental platform. Comparing with the common handling techniques, this new algorithm can greatly improve the ranging precision and the anti-jamming capability can also be enhanced.(3) Considering the disadvantage that the static state weighted centroid position algorithm based on the RSSI technical cannot solve the problems of the average error and the maximum error simultaneously, we brought forward a new Gauss fit method of dynamic weighted centroid location algorithm(GFDWCL) linked with RSSI data processing which can realize the dynamic weighted centroid via introducing differentiating function so to improve the position precision and carry out this algorithm on the experimental flat. This algorithm without additional equipments, and is low-cost and convenient to use, and do has some certain practical value on positioning of the regularly distributed anchor nodes.(4) As the WSN has to face the challenge of no central controls, calculating capacity of limited nodes, and limited communication bandwidth, low energy consuption of nodes and etc while being applied in the target tracking, we proposed the principle of a positioning algorithm based on the main node of the max-cluster, and formed out the largest cluster surrounding the object via introducing a data-base of reference points, then we can figure out the position of our objects and can also predict the orbit of the moving objscts by setting out the chief nodes and the boundary nodes. This algorithm does not need large quantity of calculations and is low-cost also, thus it can meet the requirements for WSN to track the mobile nodes in a swift and highly precise way.(5) For a certain period of time, the research works on positioning are mainly focused on how to increase the accuracy of position and how to reduce the complexity of the algorithm, but seldom concern about questions of the security. Aimed at the mostly challenging problem of how to obtain informations of the nodes securely and effectively in a resource-restricted WSN, we brought forward a kind of dispersed DPC (distance and position consistent) secure localization algorithm based on RSSI ranging. The algorithm adopts the consistency principle of the ranging and calculating to inspect and filter out the various false nodes produced by malicious attack. Meanwhile, there is no center node in this algorithm, all the nodes participate in the securelocation and the robustness is very high. The simulation experimental results of the algorithm indicates that the DPC algorithm still has a very high efficiency even in a noise circumstance or conditions with many false nodes, and can resist many kinds of malicious attacks.In the last part of the thesis, a sum-up of all the works is given, and deficiencies and the succedent researches to be done are also pointed out.