基于非线性滤波器的最大似然信道估计

在有限信道冲激响应较长的情况,由于待估计参数空间的高维数,准确计算最大似然信道估计的复杂度较高,在实际应用中通常采用近似的方法.利用非线性Teager-Kaiser滤波器在抑制噪声的同时可以有效提取信号的特征,定义了一个表征信道参数概率分布的似然比,对该似然函数的最大化是首先得到路径延迟的极值,然后求得复路径衰耗.计算机仿真结果表明,与非似然方法相比,采用该似然函数方法能使联合检测性能得到提高.

Maximum likelihood channel estimation based on nonlinear filter

For long finite channel impulse response,accurate maximum likelihood channel estimation is computationally high cost due to high dimension of parameter space,and approximate approaches are usually adopted.By utilizing the suppression of noise and extraction of signal of the nonlinear Teager-Kaiser filter,a likelihood ratio of channel estimation is defined to represent the probability distribution of ehannel parameters.Maximization of this likelihood funetion 1eads to initially searching the extrema of path delays and then the complex attenuation.Computer simulation iS conducted and the results show periormance improvements of ioint detection as compared to the non-likelihood approach.