The reading region of ultra high frequency radio-frequency identification (UHF RFID) system is affected by polarization mis- match, reader antenna height, coherent interference and so on. Based on the principles of RFID technology and ray-tracing method, a complete propagation model in real environments is derived. Utilizing recognition rate of target region (RRTR), a method of evalualing the performances of a system is presented. In order to obtain the maximization of RRTR, two solutions including tag diversity and phase switch are proposed, which combines the theories of electromagnetic propagation and coherent interference suppression. The values of RRTR under different parameters are measured in outdoor and indoor environments with a commodity hardware. The measurement results show that the values of RRTR can be enhanced by 10% and 7.6% with the two solutions respectively.%基于射频识别技术原理及射线跟踪理论,导出了实际环境中射频识别系统完整传播链路模型.提出基于目标区域识别率的系统性能评估方法,并讨论了其主要影响因素.结合电磁波传播理论及相干干扰抵消原理,提出标签集及相位开关目标区域识别率优化方法.在室内多径环境下,测试了采用标签集及相位开关优化方法的目标区域识别率.测试结果表明,两种方法下的系统目标区域识别率分别提高10%和7.6%.
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