Abstract: In order to improve the poor frequency selectivity and spectral leakage of traditional Orthogonal Frequency Division Multiplexing (OFDM) multi-carrier transceiver, multi-carrier transceiver based on modified Discrete Fourier Transform (DFT) filter bank was introduced. The design problem of it was formulated as nonconstrained minimized optimization of perfect reconstruction error of modulated filter banks, and the modified window method was taken to design the prototype filter in the modulated filter banks and linear optimization was used to optimize the objective function. Compared to the traditional window method, a spline function was exploited in the transition band of ideal filter of the modified window to eliminate the Gibbs effect. The simulation results show that the designed filter bank with the proposed method gives a better performance in terms of stopband attenuation, and reconstruction error, and the resulted multicarrier transceiver a better Symbol Error Rate (SER) performance in Quadrature Phase Shift Keying (QPSK) modulation and the 3GPP TS 25.104 vehicular multipath and one-tap frequency-domain equalization.

Key words: Discrete Fourier Transform (DFT), modulated filter bank, multi-carrier transceiver, prototype filter, spline function, Orthogonal Frequency Division Multiplexing (OFDM) modulation system

摘要： 为改善传统正交频分复用(OFDM)多载频系统频率选择性差和频谱泄露等缺陷，研究了基于改进离散傅里叶变换(DFT)调制滤波器组的多载频调制系统设计。将其设计问题归结为一个无约束的最小化调制滤波器组完全重建误差的目标函数优化问题，采用一种改进的窗函数法设计调制滤波器组的原型滤波器和线性优化方法优化目标函数。与传统的窗函数法相比，该改进窗函数法在理想滤波器的过渡带内插了一种样条函数以消除吉布斯效应。仿真结果表明，该方法设计的原型滤波器与传统的平方根升余弦方法设计的原型滤波器和一般矩形窗原型滤波器相比有更高的阻带衰减，对应的改进DFT滤波器组有更小的重建误差。基于该方法设计的改进DFT滤波器组多载频系统在正交相移键控(QPSK)调制和3GPP TS 25.104车载多径信道以及单抽头频域均衡下有更好的误符号率(SER)性能。

关键词: 离散傅里叶变换, 调制滤波器组, 多载频系统, 原型滤波器, 样条函数, 正交频分复用调制系统