Companding Transform Method for PAPR Reduction of OFDM Signals with a Variable Hyperbolic Tangent Function

• Main Authors: Jia-Hao Lin, 林家豪
• Other Authors: Dah-Chung Chang
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/32yfd3

碩士 === 國立中央大學 === 通訊工程學系 === 105 === One drawback of orthogonal frequency-division multiplexing (OFDM) is high peak-to-average power ratio (PAPR) at the transmit terminal, which leads to an important issue to study how to reduce high PAPR for OFDM. There have been many PAPR reduction approaches proposed to reduce the PAPR of OFDM signals in the past decade. The companding transform method is one of attractive methods because of the advantage of low computational complexity. Although the companding approach can effectively reduce PAPR with a proper nonlinear compression function at the tramitter, the symbol error rate (SER) perfomance is seriously degraded because of noise amplification due to the expanding characteristics of the inverse of the compression function at the receiver.\\ In this thesis, a variable hyperbolic tangent companding function is studied to take PAPR and SER into joint consideration for a practical performance tradeoff. Through theroretical anlaysis of the PAPR and SER performances of M-QAM for OFDM with the inverse hyperbolic tangent function for the expander, we design an index for joint consideration of PAPR and SER performances to explore a proper parameter for guiding the hyperbolic tangent companding function. Simulation results show that with the index, the proposed PAPR reduction method has a well tradeoff of the PAPR and SER performances.