Transmitter Signal Precessing Techniques to Reduce Nonlinear Effects in 802.11a Systems

• Main Authors: Chia-Ling Shen, 申家玲
• Other Authors: Ying Li
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/11346919600784064422

碩士 === 元智大學 === 電機工程學系 === 90 === The IEEE 802.11a standard adopts Orthogonal Frequency Division Multiplexing(OFDM) signals.OFDM signal exhibits large peak-to-average power ratio(PAPR), and thus is vulnerable towards transmitter nonlinearity. The nonlinear effects will lead to the increase of inband signal error rate and outband intermodulations. We discuss two techniques to reduce the nonlinearity : (1) peak windowing , (2)predistortion. We compute minimum output backoff (OBOmask) required for the transmit signal power spectrum to satisfy the IEEE 802.11a spectrum mask. OBOmask reflects outband suppression performance. We also evalute the BER curves that reflect inband received signal quality. Simulation results show that using peak windowing alone has limited effect in promoting signal quality and suppressing outband intermodulations. Using predistortion alone performs very well. Using peak windowing and predistortion together perform well, too.