| Extensive attention has been paid to the Internet of Things in recent years. As two of its four key technologies, the wireless sensor network technology and Radio Frequency Identification (RFID) technology in the perception layer play an important role in connecting the physical world to the cyber space.This thesis studies the localization in wireless sensor networks (WSNs) and anti-collision counting of RFID tags. First, it describes some relevant theories of the Internet of Things, development profile and applications. It gives a brief introduction to the related concepts, classifications, and positions of the two problems in the Internet of Things. The recent progress in related research and some excellent solutions of the problems are reviewed. Then two methods to solve the problems are given. To improve localization precision, we propose an elastic force-based sensor network node positioning approach. To advance the throughput of RFID Tag counting, we propose an ALOHA-based tag anti-collision counting method. Extensive simulations are performed using MATLAB to evaluate the proposed algorithms. Results show that the proposed algorithms are better then the corresponding existing methods in some respects.The main contributions of this work are as follows. We design a localization system in WSNs which abstracts the distance of every neighboring nodes pair as the length of a spring between them, and then gets the final position information through coordinates updating. Compared with other spring-based locating methods, this algorithm converges faster. The benefits come from using a displacement vector in updating coordinates which is proved neither bigger nor smaller in the direction. In the RFID system, the goal of our algorithm becomes maximizing the throughput rather than accurately estimating the number of tags. Our ALOHA-based anti-collision solution outperforms existing methods in throughput and reduces the number of reading rounds if necessary. |
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