中文摘要：

针对现有压扩变换法系统性能差的缺点，提出了一种降低系统峰均功率比的部分压扩算法。该方法根据正交频分复用（OFDM）系统信号幅度服从瑞利分布的统计特性．仅压缩大幅度信号保持了系统信号幅度的分布特征，弥补了现有压扩变换的不足，且具有带外功率小的优点。在M阶调制方式下的系统仿真结果表明，部分压扩方法与选择性映射和部分传输序列等方法相比．可获得相近的蜂均功率比压缩效果并且在同样的系统误码率条件下比指数压扩法获得约log2（M）dB信噪比增益。

英文摘要：

Aiming at the drawbacks of traditional companding methods to reduce peak-to-average power ratio（PARR） in orthogonal frequency division multiplex （OFDM） communication system, a partial companding method was proposed in this paper. According to the rayleigh distribution property of OFDM signal magnitude, an partial oompanding method was proposed in this paper to reduce PAPR for OFDM system. The method reduces PARR by only compressing the sig- nals greater than a given threshold, while maintaining the distribution characteristic of OFDM signal magnitude with less spectrum side-lobes than conventional companding scheme. Simulation results for M-order modulation methods showed the partial oompanding method could obtain similar PARR compressing effect to partial transmit sequences （PTS） method and selected mapping （SLM） method, and about log2 （M）dB BER gain for M-QAM modulation than the canvantional companding method.