Reduction of PAPR using companding with pre-distortion
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摘要: 针对压扩法中峰均功率比抑制与系统误码率之间的矛盾,提出了一种压扩与预失真结合的方法.用Bussgang定理推导出正交频分复用信号经过非线性功率放大器后,在加性高斯白噪声信道下子载波信噪比的计算公式.用理想预失真代替非线性功放,再对线性压扩法进行改进.用理想预失真和改进后线性压扩的3个参数修改子载波信噪比计算公式,进而得到系统误码率.仿真结果表明:通过调整3个参数,在获得相同峰均比抑制效果及误码率的情况下,所提出方法的信噪比门限改善了0.8 dB.Abstract: To solve the conflict between peak to average power ratio (PAPR) and bit error ratio (BER) in companding, a joint companding pre-distortion (PD) method was proposed. The closed form expression of subcarrier signal to noise ratio (SNR) of orthogonal frequency division multiplexing (OFDM) signal, which was distorted by nonlinear power amplifier, was deduced under additive white Gaussion noise (AWGN) channel using Bussgang theorem. The nonlinear power amplifier was replaced by ideal PD. Then the linear companding was modified. The new expression of subcarrier SNR was obtained using three parameters of ideal PD and modified linear companging. The system BER was calculated by the new SNR. The simulation results show that, by adjusting the three parameters, the SNR threshold can be improved by 0.8 dB under the same PAPR reduction and BER.
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