【作者】 熊廷文；

【导师】 闵昊；

【作者基本信息】 复旦大学 ， 微电子学与固体电子学， 2010， 博士

【摘要】 基于超高频射频识别技术的实时定位系统由于具有诸多优点而成为当前室内无线定位技术的研究热点。然而,受到无源标签的低成本、低功耗和系统窄带宽的限制,要想实现射频识别读写器对无源标签的精确定位,难度较大。本文将伪码测距理论和多点定位理论引入超高频RFID系统,结合系统本身的信号传输特点,提出了一种基于无源超高频射频识别技术的实时定位方案,并对此进行一系列的研究。首先,本文分析了超高频射频识别系统的信号传输特点,提出了基于伪码测距和多点定位的射频识别实时定位方案；研究了方案的可行性、技术难点和预期的解决办法。其次,本文分析了系统的功率传输特点和链路特性,计算了主要的系统指标；针对系统收发同时同频,发射到接收泄漏较大的技术难点,提出了基于载波泄漏对消的收发机架构。再次,本文研究了射频识别实时定位系统的几个关键技术,包括测距码及其相关特性,系统的同步问题,以及系统的测距精度等等；设计了一种适用于本系统的测距码、同步控制环路以及低复杂度四并行匹配滤波器构成的相关器,分析了三种提高系统测距精度的方法。然后,本文设计了一种超高频射频识别实时定位读写器,包括载波泄漏对消器、射频收发机和数字基带信号处理三个部分,并分别进行详细的性能分析；分别在ADS软件和Matlab/Simulink中搭建了基于载波泄漏对消的读写器射频前端的频域模型和基带复包络时域模型,采用Matlab和Modelsim协同仿真方法对所设计的读写器前端和数字基带信号处理进行全面的系统仿真,结果验证了整个系统的功能。最后,本文实现了一个基于载波泄漏对消的实时定位系统的原型机,包括实时定位读写器和标签两部分；制订了详细的测试方法来验证所提出的系统方案。测试结果表明所设计的原型机达到预期的设计指标,所提出的基于无源超高频射频识别技术的实时定位系统方案正确、可靠,校准后的平均测距精度达到0.5m,定位精度为0.79m2。更多还原

【Abstract】 Real Time Locating System (RTLS) based on Ultra High Frequency (UHF) Radio Frequency Identification (RFID) is promising due to lots of advantages, and it has been becoming a research focus of indoor location technology recently. However, limited by low cost and low power of passive tags and narrow bandwidth of the system, UHF RFID reader can not locate the tags with high accuracy unless it has been improved drastically. Pseudo-random Number Ranging (PNR) method and multi-point location theory have been introduced into the system, and a passive UHF RFID-based RTLS has been proposed and validated in this dissertation.Firstly, signal transmission characteristics of the system are discussed, and a UHF RFID-based RTLS using PNR method and multi-point location technique is put forward. The feasibility, the difficulties and possible solutions of the proposed system are analyzed.Secondly, power transmission characteristics of UHF RFID are discussed and main system parameters are calculated. A Leaking Carrier Canceller (LCC) is adopted to suppress the large leakage due to insufficient isolation between the transmitter and the receiver. A LCC-based RF transceiver architecture is proposed.Thirdly, several key technologies of the system are analyzed, including the auto-correlation of ranging codes, the synchronization and the overall accuracy of the system. A 125-bit shortened m sequence is selected as the ranging code, and a synchronization control loop and a low-complexity correlator comprised of four parallel matched filters are designed. Three techniques of improving the accuracy are discussed.Fourthly, a UHF RFID-based real time locating reader is designed and analyzed, including a LCC, a RF transceiver and a Digital Signal Processing (DSP) block. The LCC and the transceiver have been modeled in ADS (Advanced Design System) and Matlab/Simulink for frequency-domain and time-domain performance analyses, and the DSP block has been co-simulated by Matlab and Modelsim. Simulated results testify the function of the whole system.Finally, a prototype of passive UHF RFID-based RTLS has been implemented, including a real time locating reader and two tag emulators. A detailed testing plan has been established to test the prototype and to validate the system. Measured results indicate that the prototype meet the requirements of RTLS, with the average accuracy 0.5 m and locating area 0.79 m2, which prove the correctness and reliability of the proposed system.更多还原