The Research Of Anti-Collision Algorithm In RFID

Internet of things (IoT) is a novel paradigm that is rapidly gaining ground in the scenario of modern wireless telecommunications. The basic idea of this concept is the pervasive presence around us of a variety of things or objects-such as RFID (Radio Frequency IDentification) tags, sensors, actuators, mobile phones, etc. Nowadays, the Internet of things is called the world’s third wave of information industry followed with the computer and network industry. The Internet of Things which bases on Internet will be using Electronic Product Code and Radio-Frequency Identification to realize interconnection between product and product. To identify tag that involves Electronic Product Code is the first important question among many key techniques of Internet of Things.In tag intensive RFID applications system, there are a lot of tags collisions. These collisions have evil effects on increasing the reader’s tag throughput and on improving the performance of the whole RFID application system. In order to read information properly from these tags, the reader must adopt an anti-collision algorithm. One of the critical influencing factors of the reader’s tag throughput is the performance of the anti-collision algorithm it used. Therefore, the multi-tag anti-collision algorithm plays a very important role in tag-intensive RFID application system.First of all, a comprehensive review of the state of arts of RFID multi-tag anti-collision algorithms is given out on the basis of consulting plenty of domestic and foreign related literatures. There are several tag anti-collision algorithms proposed to reducing tag collision. The algorithms can be categorized into two classes:ALOHA based and tree-based algorithms. And do performance analysis on these algorithms. ALOHA based algorithms have the tag starvation problem; deterministic tree-based algorithms have the problem that their performances are influenced by the length or the distribution of tag IDs.Secondly, based on the existing methods of performance analysis, discuss the shortcomings of them. In order to solve the defects of the existing algorithm and to improve the efficiency of system identification, this thesis put forward a kind of high efficient anti-collision algorithm, ASPA algorithm. This algorithm adopts the adaptive splitting and the pre-signaling methods. When there are tags whose responses collide, a typical tree-based algorithms, such as ISO/IEC18000-6B protocol, split colliding tags into two subgroups no matter how many colliding tags are. The idea of adaptive splitting scheme is to estimate the number k of colliding tags and to split the colliding tags into k groups to speed up the identification procedure. To enhance the performance of the identification procedure, we propose the idea of pre-signaling under the assumption that the reader can distinguish three cases of identical responses from multiple tags by signal strength inspection. The cases are:no-response, one-response and multiple tags response. The pre-signaling is to set a pre-signaling window, to predict the response of next interval, in order to dispose at an early date. One reader command can carry more information, which reduces the amount of transmitter data information, speeds up the identification rate.Finally, we show simulation and analysis results. We simulate ASPA and compare it with ISO/IEC18000-6B protocol in terms of the number of tag collisions, the number of messages sent by the reader and the time needed to identify all tags in the interrogation zone. We also compare the system efficiency of ASPA, FSA and ISO/IEC18000-6B protocols. The result shows that anti-collision performance of ASPA is much better than random binary anti-collision algorithm adopter in ISO/IEC18000-6B protocols.