【作者】 熊樑；

【导师】 许贵平；

【作者基本信息】 华中科技大学 ， 计算机技术， 2011， 硕士

【摘要】 近年来,随着物联网概念提出以及RFID射频识别技术在沃尔玛供应链管理上的成功运用,使得以往仅用于军事领域的RFID技术,凭借其成本低、体积小、无须接触等特性越来越多的运用在生产自动化、门禁、公路收费、货物跟踪等民用领域中。然而,由于受到各种环境和射频技术本身的一些特点,RFID阅读器识别标签时会发生各种错误识别现象:积极读、消极读、标签冗余、阅读器冗余,这一些因素都会制约着RFID技术应用进一步发展。对上述几种脏数据,分别采用相应的算法加以清洗。由于RFID原始数据流具有无限性,因此在清洗算法中使用了滑动窗口技术。其中,消除积极读实质上是去除原始数据流中的噪音,算法通过统计滑动窗口中的标签个数来判断标签是否为噪音;去除消极读是通过时间平滑操作达到目的,时间平滑操作是指在时间维上不足漏读的标签;去除标签冗余是使标签数据流中相邻标签时间间隔大于某个阀值;去阅读器冗余则是在空间上对标签数据进行平滑,即合并多个阅读器标签流并同时保持标签输出时标有序。针对平滑处理算法中滑动时间窗口设置难的问题,提出了一种基于阅读器部署结构设置窗口大小的方法,该方法的优势在于不必频繁修改滑动窗口大小而影响系统的性能。在RFID系统安全保护方面,系统采用一种基于安全等级的访问控制策略。针对清洗系统性能方面,通过动态地调整清洗服务节点的清洗任务减轻了单个清洗服务器节点的负载压力,较好的实现了系统稳定和高效的要求。系统通过仿真实验证明,使用清洗负载动态均衡策略有效的提高了清洗处理的运行效率。更多还原

【Abstract】 Before RFID technologies were only used in the area of military. In recent years, with the emergence of Internet of Things, because of RFID products’ small size, low cost, no contact reaction, RFID technologies have been widely used in supply chain management, production automation, entrance guard, highway toll, cargo tracking and other civilian areas. Some problem may occur when RFID reader identifies tags because of some environmental factors. These problems include false positive readings, false negative readings, tag duplicated readings and reader duplicates. These negative facts would affect development of RFID applications.To clean raw RFID readings with those problems some algorithms are described in this thesis. Because of the infinity of the RFID data stream, RFID data cleaning make use of sliding window techniques. Eliminating false positive readings is essentially removing the noise data from the raw data stream. The algorithm for this purpose determines whether tag was noise by counting the number of the tag in the sliding window. The algorithm for solving false negatives uses the time smoothing technique, which is essentially recompensing the lost tags in the time dimension. By keeping that the timestamp interval between two adjacent tags is longer a certain threshold, redundant data are removed. Removing the spatial redundancy is smoothing data in spatial dimension, which is merging multiple tag streams and keeping the tag timestamp order. The thesis proposes a technique based on the spatial deployment of readers to set window size. The advantage of the method is that the change rate of sliding window size is low and has little effect on performance of clean process. In the terms of RFID security protection, the system also apply an access control policy based on tag and reader level security. In order to improve the performance of cleaning system, a strategy using clustering and dynamic load balancing techniques is proposed.Simulation experiments show that the using dynamic load balancing strategy effectively improve the efficiency of data cleaning.更多还原