DFT扩展OFDM系统中降低信号峰均比的频域成型方法

Frequency Domain Shaping Methods for PAPR Reduction in DFT-Spread OFDM System

OFDM(正交频分复用)技术的主要缺点之一是其发送信号具有较高的峰均比。DFT(离散傅里叶变换)扩展OFDM系统的发送方案可以有效降低信号的峰均比。在该系统中,频域成型方法不仅对系统有无码间干扰的特性和抗噪声性能有重要影响,而且对发送信号的峰均比也有重要影响。文中首先在加性高斯白噪声信道下推导了无码间干扰和接收机最大输出信噪比条件下发送频域成型函数及接收频域成型函数所要满足的条件,然后根据该条件设计了几种频域成型方法。仿真结果表明,频域成型方法能进一步有效降低发送信号的峰均比。

One of the major drawbacks of Orthogonal Frequency Division Multiplexing （OFDM） system is its high peak-to-average power ratio （PAPR） of transmitted signals. The DFT-spread OFDM （DFr-S-OFDM） system can effectively improve the PAPR performance. In DFT-S-OFDM system, the frequency domain pulse shaping filters, both in the transmitter and the receiver, decide the, existence of inter-symbol interference （ISI） and the output SNR of the receiver. The frequency domain filter in the transmitter also has a great effect on the PAPR of the transmitted signals. In this paper, we first derive the conditions of frequency domain pulse shaping filters for ISI - free and maximum output SNR of the receiver. According to the derived conditions , several classes of frequency domain pulse shaping filters are selected. Simulation results show that the DFT - S - OFDM with properly designed frequency domain pulse shaping filters could further improve PAPR performance.