图7 限幅滤波的PAPR分布
图8显示了使用限幅滤波技术的BER性能曲线。由图8可以看出OFDM信号传输BER与信噪比([EbN0])的性能曲线关系,直接限幅将导致非线性失调,降低系统传输性能,当[CR]减小时,BER性能变得更差,在信噪比为10,CR=1.6时,采用限幅滤波技术的传输BER约为0.005 3,若直接使用限幅的传输BER约为0.011 0。直接采用限幅技术会产生带外噪声,导致系统性能下降。因此,限幅滤波技术比直接采用限幅技术更有效地减小OFDM系统PAPR的同时也提高了系统的性能。
4 结 语
本文采用限幅滤波技术减小OFDM系统的PAPR,并进行相关仿真与分析,仿真结果表明,本文采用的限幅滤波比直接采用限幅技术更加有效地减小OFDM系统的PAPR,同时降低带内失真和带外辐射等,提高了系统的系能。但该方法也有缺点,例如限幅滤波方法是通过滤波器来改善限幅失真,滤波需要进行IFFT和FFT运算,增加了计算复杂度。因此,今后需要进一步优化算法,提高OFDM系统的性能。
图8 限幅滤波的BER性能
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