一种用于超高频RFID读写器的载波泄漏抑制改进算法

An Improved Leaking Carrier Canceller Algorithm for UHF Reader

在超高频RFID系统中,评价系统性能的两个关键指标是最大读写距离和识别率。当读写器采用基于单天线的环形器或耦合器隔离方案,由于接收信号和发送信号同频率,发射通路的载波信号会泄漏到接收通路,降低接收机的灵敏度,从而大大降低读写器的性能,严重影响RFID系统的应用。为了解决环形器或耦合器隔离度不高导致的载波信号泄漏问题,常用解决方法是在读写器中增加一个载波泄漏抑制模块,提高收发通路之间的隔离度。本文在原有梯度搜索范围上进行了优化,将IQ复平面的相位多等份分割,以此构造不同相位试探信号快速定位抑制信号相位搜索范围,提供了一种高效载波泄漏抑制信号的产生方式;并且通过与其他常用的载波抑制方法的对比分析,证明了改进算法的高效性。

In passive UHF RFID systems, two key evaluation measurements of the system＇ s performance are maximum reading distance and recognition rate. When the reader using ring or coupler isolation scheme in RF, receiving signals and transmitting signal are at the same frequency, which will result in that the carrier signal in transmission path will leak into reception path, it will reduce the sensitivity of the receiver, and thus greatly reduce the reader performance, seriously affect the application of RFID systems. To solve the low isolation problem of the carrier signal leakage using ring or coupler, commonly used solution is to add a leakage carrier canceller which improve the isolation between reception path and transmission path. On the basis of gradient search algorithm, we divide the IQ complex plane into equal parts to generate probe signals in different phase with same frequency, and offer an efficient way to produce the carrier leakage suppression signal. At last, the measurement results, which are compared to the theoretical findings, show that our approach is more efficient.