一种DTMB系统信道估计改进算法

为减小拖尾效应和加性噪声对数字电视地面广播(DTMB)系统的信道估计精度的不利影响,针对DTMB系统帧头模式2下的信道估计,提出一种改进的最小二乘(LS)信道估计算法.该算法采用试凑法从DTMB系统信号帧中PN帧头序列内选取最佳的一段PN序列,利用所选取最佳PN序列构造用于改进的LS信道估计算法的最优频域子载波,使用改进的LS信道估计算法获取信道的脉冲响应估计初值;并根据信号的正交振幅调制(QAM)方式,选取最佳噪声门限对信道的脉冲响应估计初值进行时域滤波去噪,以获得信道脉冲响应终值.仿真结果表明,该算法可有效减小拖尾效应和加性噪声对信道估计精度的影响,提高DTMB系统在帧头模式2下信道估计的精度.

An Improved Channel Estimation Method Based on DTMB Systems

In order to reduce the adverse influence of smearing effect and additive noise on the channel estimation precision of digital television terrestrial multimedia broadcasting(DTMB) system,an improved least squares(LS) channel estimation algorithm based on DTMB system in the frame head of mode 2 is proposed.By using the method of trial and error,this algorithm cuts a best piece from the pseudo noise(PN) sequences of the signal frame based on DTMB system,which is used to build optimal frequency sub carriers used for improved LS channel estimation,and an initial value of the channel impulse response is obtained through adopting improved LS algorithm.Meanwhile,the best noise threshold is selected for time domain filtering to obtain the final value of the channel impulse response according to different quadrature amplitude modulation(QAM) methods of the signal.The simulation validates that the algorithm can decrease the adverse influence of smearing effect and additive noise on the channel estimation precision,and improve the accuracy of channel estimation for DTMB in the frame header of mode 2.