| Thanks to the joint effort from both academia and industry, RFID (Radio Frequency Identification), which is an emerging technology in the realm of Information Technology, has being maturing technically as well as increasing in value day by day. However, due to the various fading effects of electromagnetic wave in the wireless channel, together with the interference of material, motion and environment, and the orientation sensitivity of antenna, RFID performance becomes unreliable and unpredictable in real-world applications. Thus, the study of RFID application performance has been put on the agenda. Supposing we have grasped the objective law of how the system performance is influenced, it will definitely give guidance to the practical application and create enormous social-economic value in the meantime. Theoretical analysis and experimental study have allowed us an in-depth understanding of this problem. While using these approaches comprehensively, with their respective strength exerted, we can more often than not, reach more insightful conclusions.In this thesis, mainly by employing the approach of machine-aided experiments and protocol parameters analysis, we discuss both internal and external factors that influence UHF RFID system performance, and the target application scenario is ubiquitous computing environment. Core characteristics requirement of RFID application is derived and a series of fundamental experiments are designed accordingly. Multi-tag mobile performance index, which is superior to the traditional RFID performance evaluation method, is proposed. The impact of mobility on RFID performance is understood thoroughly. The matching between RFID reader mode and application scenario is achieved quantitatively. The so-called pause effect, entering effect and separate effect are discovered and named to be three phenomena that could affect the actual RFID performance, thus recommendations on better reader design as well as empirical guidelines for reader configuration are given. The results of our study can facilitate the deployment of RFID system, substantially improving its effectiveness and reliability.First of all, the state of the art of the approaches to studying RFID performance has been summarized as four main methodologies, namely benchmark testing, parameter analysis, mathematical & physical modeling and field experiment. The C1G2 air interface protocol and Experimental Design methodology are introduced for follow-up reference. Second, taking the characteristics requirement of RFID in typical application scenarios and related technical difficulties as a starting point, we derive proper experiments for analyzing RFID application performance. Then, RFID application performance evaluation system is analyzed, fundamental questions like the influence of mobility and tag set size, the interference from environment and material as well as tag write performance are discussed in detail. Moreover, an integrated problem of how to match reader mode with application scenario is discussed and its factorial design given. The final part of this thesis is about the building of the experimental platform and the discussion of the experimental results. The key to the former one lies in a circular conveyor belt system and the proper programming to the reader interface. The result of mobile experiments shows that latency time is the major factor that restrains multi-tag mobile performance, while multipath effect is the minor cause. The result of scenario matching experiment indicates that there's a strong interaction between communication data rate and tag density, and by taking advantage of this interaction we can achieve system performance optimization and prediction. |
