MR64QAM/OFDM传输系统中的非线性分析

研究了固态功率放大器（ＳＳＰＡ）非线性失真对正交频分多路复用（ＯＦＤＭ）数字高清晰度电视（ＨＤＴＶ）传输系统性能的影响．采用预失真法改善ＳＳＰＡ的非线性失真，并将ＳＳＰＡ等效为一个软限幅器．计算了在加性噪音和软限幅影响下多分辨率调制（ＭＲ）６４ＱＡＭ（正交幅度调制）／ＯＦＤＭ的传输系统误比特性能．结果表明，０．１％的限幅概率对ＭＲ６４ＱＡＭ／ＯＦＤＭ传输系统所造成的信噪比损伤可忽略不计，产生的邻频道干扰为－４９．２ｄＢ；１％的限幅概率对ＭＲ６４ＱＡＭ／ＯＦＤＭ传输系统在最重要比特误比特率为１０－１０时所造成的信噪比损伤为１．９ｄＢ，产生的邻频道干扰为－３７ｄＢ．

Nonlinear Analysis of MR64QAM/OFDM Transmission System

The nonlinear distortion effects of a solid state power amplifier (SSPA) on the transmission system of orthogonal frequency division multiplexing (OFDM) digital high definition television (HDTV) were investigated. A predistorter was used to improve the nonlinear distortion of SSPA. An SSPA with predistortion could be equivalent to a soft limiter. The bit error performance (BER) of multiresolution (MR) 64QAM (Quadrature Amplitude Modulation)/OFDM transmission system in the presence of additive gaussian noise and soft clipping noise was calculated. The results indicate that the induced signal to noise (SNR) penalty is negligible for 0.1% clipping and about 1.9 dB for 1% clipping at the most important bit of BER=10 -10 , and the induced adjacent channel interference is -49.2 dB and -37 dB, respectively.