介绍一种将自适应噪声抵消算法应用于消除周期性工频脉冲干扰的方法。该方法利用周期sinc函数仿真工频脉冲干扰信号,与白噪声叠加作为参考输入,利用最小均方(Least Mean Square,LMS)算法与归一化最小均方(Normalized Least Mean Square,...介绍一种将自适应噪声抵消算法应用于消除周期性工频脉冲干扰的方法。该方法利用周期sinc函数仿真工频脉冲干扰信号,与白噪声叠加作为参考输入,利用最小均方(Least Mean Square,LMS)算法与归一化最小均方(Normalized Least Mean Square,NLMS)算法进行自适应噪声抵消滤波仿真实验。MATLAB仿真处理结果显示,在无增益、增益饱和、增益过饱和这三种情况下,当信噪比为3 d B时,分别用LMS算法与NLMS算法滤波后可以清晰地分辨多次回波。展开更多
Due to frequency-selective and time-variant property of wireless channel together with additive noise and mismatch of oscillators between transmitter and receiver, there are always time and frequency synchronization e...Due to frequency-selective and time-variant property of wireless channel together with additive noise and mismatch of oscillators between transmitter and receiver, there are always time and frequency synchronization errors in a practical OFDM system. To investigate the effect of the two kinds of errors on system performance, the average normalized interference power (NIP) is defined. A simple supper bound for NIP caused by time synchronization error (TSE) and the tighter upper bound for NIP resulting from frequency synchronization error (FSE) are derived independently. Simulations in typical short wave (SW) and medium wave (MW) channels further verify the correctness and tightness of these upper bounds. They actually provide good approximations to NIPs. Moreover, the upper bound for NIP resulting from FSE is tighter than traditional upper bound. Additionally, a new solution is proposed to relax the precision requirement for time synchronization algorithm, which can achieve a better tradeoff between time synchronization precision and bandwidth efficiency. These upper bounds will be useful in developing and choosing time and frequency synchronization algorithms in OFDM system to achieve a specific NIP value for a given channel condition.展开更多
文摘介绍一种将自适应噪声抵消算法应用于消除周期性工频脉冲干扰的方法。该方法利用周期sinc函数仿真工频脉冲干扰信号,与白噪声叠加作为参考输入,利用最小均方(Least Mean Square,LMS)算法与归一化最小均方(Normalized Least Mean Square,NLMS)算法进行自适应噪声抵消滤波仿真实验。MATLAB仿真处理结果显示,在无增益、增益饱和、增益过饱和这三种情况下,当信噪比为3 d B时,分别用LMS算法与NLMS算法滤波后可以清晰地分辨多次回波。
基金supported by the National Natural Science Foundation of China(Grant No.60496311).
文摘Due to frequency-selective and time-variant property of wireless channel together with additive noise and mismatch of oscillators between transmitter and receiver, there are always time and frequency synchronization errors in a practical OFDM system. To investigate the effect of the two kinds of errors on system performance, the average normalized interference power (NIP) is defined. A simple supper bound for NIP caused by time synchronization error (TSE) and the tighter upper bound for NIP resulting from frequency synchronization error (FSE) are derived independently. Simulations in typical short wave (SW) and medium wave (MW) channels further verify the correctness and tightness of these upper bounds. They actually provide good approximations to NIPs. Moreover, the upper bound for NIP resulting from FSE is tighter than traditional upper bound. Additionally, a new solution is proposed to relax the precision requirement for time synchronization algorithm, which can achieve a better tradeoff between time synchronization precision and bandwidth efficiency. These upper bounds will be useful in developing and choosing time and frequency synchronization algorithms in OFDM system to achieve a specific NIP value for a given channel condition.
