降低OFDM信号峰均功率比的分段线性压扩变换

摘要

In order to reduce the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals, a piecewise-linear companding transform was proposed. Small amplitudes were multiplied by a scale factor, while large ones were not only multiplied by a scale factor but also added by a shift. The resulting companding transform was piecewise-linear and continuous. It can provide significant PAPR reduction performance with low computational complexity, and has low influence on system performances through piecewise transform. It is shown by theoretical analysis and simulation that, a good trade-off between PAPR reduction and bit-error-rate performances can be achieved by carefully choosing the two scales and the shift. Furthermore, compared with existing linear and nonlinear companding transforms, a better power spectral density performance can be achieved.%为了降低OFDM信号的峰均功率比(PAPR),设计了一种分段线性压扩变换.对小幅度通过数乘变换进行线性放大,而对大幅度先利用数乘变换进行线性缩小,再对缩小后的幅度进行等量放大.得到的压扩变换是分段线性且连续的,用低复杂度的线性运算抑制峰均比,同时用分段的方法减小压扩对系统性能的影响.理论分析和仿真表明,通过数乘因子和增量数值的选取,可以在PAPR抑制和系统误码率性能上取得折中.相比于已有的线性和非线性压扩变换,改善了发送信号的功率谱密度特性.