Biography
Enrollment Date: 2008
Graduation Date：2011
Degree：M.S.
Defense Date：2011.05.24
Advisors：Chun Zhang
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：The Adaptive Digital Predistortion Design in RFID System
Abstract:
As a new communication technology, the RFID technology has won more and more attention. Correcting the distortion in the RFID system has been a important problem to be solved. The nonlinearity mainly comes from the nonlinear components in the RFID system and the using of the non-constant envelope modulation, which will cause harmonic components and inter-modulation distortion, thus enhance the adjacent channel power ratio and the bit error ratio in the system. Based on the LUT method, a novel adaptive digital predistortion method with the interpolation design is presented in this paper. 1. By using the interpolation design, only the predistortion weights of the typical values in the output characteristic curve are saved in the LUT, which reduces the size of LUT and the hardware resources greatly. 2. The fixed update step and the variable update step are designed to get the optimum configuration, which enhanced the training speed obviously. 3. A new indicator of the linearity is designed to reduce the computation. Also, an indicator is designed to control the process of the predistortion. A lot of simulation has done in the MATLAB platform, which indicates that the effect of the adaptive digital predistortion is quite useful. Compared to the RFID system without using the predistortion design, the training cycle is reduced to 81%, the harmonic components is reduced by 24 dB, the inter-modulation distortion is reduced by 28 dB, and the spectrum of the output signal in the RFID system meets the requirements of the national spectrum norms. With the help of the interpolation design, the size of the LUT is reduced to 1.6 % of its full size. This design is also tested in the FPGA platform. Also, a high-performance RFID verification platform is designed to test the adaptive digital predistortion method and other designs in the RFID system. Keywords: RFID adaptive predistortion interpolation