在移动 RFID 系统中防碰撞协议的系统性能评估方法

摘要

Study on anti-collision protocols in static scenarios has matured since these years. System properties of all anti-collision protocols can be well evaluated by system efficiency. In many real applications ,however , tags attached to items always move along the fixed path in the reader coverage area ,which is referred to as the mobile RFID system. This implies that tags stay in the reader coverage area for bounded time (sojourn time).Since the limited sojourn time of tags and the random identification delay may cause some tags leave the cover-age area unidentified(tags loosing) ,obviously ,the tag loss ratio(TLR)becomes a most important performance index. So far TLR in the mobile RFID system ,TLR can be obtained by computation only with the frame slot-ted ALOHA protocol. And computation of TLR is extremely time-consuming due to increasing of tag popula-tion.However ,there is not any good method to obtain TLR with other anti-collision protocols. In this paper , the simplied mobile RFID systems model was presented. By the model ,TLR of various anti-collision protocols could be obtained easily in the mobile RFID system.%目前，对于静态场景下防碰撞协议的研究已比较成熟。通过系统效率，各种防碰撞协议的系统性能可以得到较好的评估。然而，在许多实际的RFID应用系统中，标签通常附在物品上并在信号区内沿着固定路径移动，该场景叫做移动R F ID系统。这意味着标签在信号区的停留时间是有限的，标签在信号区停留时间的有限性和标签识别的随机延迟会导致部分标签没有识别就离开信号区（丢失标签），此时，标签丢失率 TLR是最为重要的性能指标。迄今为止，在移动RFID系统下，只有固定帧长ALOHA协议的TLR可以用数学计算的方式获得，但是计算量非常大，而其他防碰撞协议还没有较好的方法获得 TLR。本文提出一种简化的移动RFID系统模型，通过该系统模型，各种防碰撞协议在移动RFID系统下的TLR能够较容易的获得。