一种改进的TDS-OFDM信道估计算法

An improved channel estimation scheme for TDS-OFDM system

为提高信道估计精度,提出了一种改进方法.该方法首先利用时域相关方法获取信道脉冲响应的初始估计值,选取其中幅度较高的抽头,构造一组线性方程.通过解方程组,消除相互间的干扰,得到这些抽头位置的信道脉冲响应精确估计值.然后计算它们对其他抽头位置脉冲响应的干扰,最后从初始估计值中减去这些干扰,即可得到更精确的完整信道估计.计算机仿真结果表明,与传统的时域相关算法相比,该方法在高信噪比条件下可使等效解调器的输出信噪比提高5dB,或信道估计的均方误差降低一个数量级.此方案可用于高精度的调制信号分析、测量,并已成功应用于某种型号的调制信号分析仪中.

To improve the accuracy,an improved scheme is proposed.In this scheme the initial estimation of channel impulse response（CIR） is acquired first through time domain correlation.By selecting CIR taps with higher initial estimated amplitude,equations are constructed.Through solving these equations,more accurate estimation of the selected CIR taps can be obtained and their interference to others can be calculated.Finally this interference from initial estimations is deducted and the more accurate channel estimation is obtained.Computer simulation is conducted to verify the effectiveness of proposed scheme.Simulation results show,compared with time domain correlation channel estimation algorithm,in high signal to noise ratio（SNR） region,the proposed scheme can improve the equivalent demodulator output SNR by 5dB,or decrease the channel estimation mean square error（MSE） by 10-1 times.The scheme is suitable for modulation signal analysis and measurement which require high precision,and has been applied successfully to a kind of modulation analyzer.