Adaptive Nonlinear Predistortion Filter in OFDM Systems

• Main Authors: JHAO, YI-SYUAN, 趙逸軒
• Other Authors: LIN, JUI-YUAN
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/hwkwhg

碩士 === 南臺科技大學 === 電子工程系 === 107 === Over the past decade, OFDM has become a popular technology due to its high spectral efficiency and has performed well against multipath fading in communication environments. Moreover, OFDM is considered to be an efficient technology application for high bit rates, such as digital television broadcasting and wireless local area networks. OFDM signals are very sensitive carrier systems when high power amplifier (HPA) is non-linear. Therefore, the performance of an OFDM system is significantly reduced due to HPA nonlinearity. In order to reduce the performance degradation due to the nonlinear effects on the transmitted signal, a compensation circuit must be used to eliminate the nonlinear distortion of the HPA. This thesis proposes an adaptive nonlinear filter to compensate for the nonlinear distortion of HPA. An adaptive algorithm for adjusting the predistorter parameters is then derived using a stochastic gradient method. Finally, computer simulations show that the performance of the Taylor series expansion predistortion filter can be significantly improved by using the proposed adaptive nonlinear predistortion filter.