| Nowadays,with the rapid development of communication industry,people have higher and higher demand for communication transmission,which promotes the continuous innovation of communication network.Large scale multiple input multiple output technology is regarded as the key technology of mobile communication because of its great advantages in improving system capacity and spectrum efficiency.In large-scale MIMO systems,the spatial alternating generalized expectation maximization(SAGE)algorithm in the channel estimation algorithm can accurately and effectively estimate the channel parameter information,so it is widely used.This thesis focuses on the channel parameter estimation method based on SAGE algorithm.It is found that when the delays of multiple paths in the channel are equal or close,the low-power path cannot be estimated.In order to solve this problem,a SAGE optimization method is proposed in this thesis,which takes the path whose power is lower than a certain threshold as the noise elimination when estimating the sub path.Simulation results show that the improved SAGE algorithm can estimate the path submerged by noise in the original algorithm,improve the accuracy of parameter estimation,and speed up the iterative convergence speed.In view of the high sensitivity of Doppler to noise information in SAGE algorithm,an improved SAGE algorithm is further proposed to prolong the search time in time dimension when estimating Doppler parameters.The improved algorithm considers extending the search range of Doppler parameters and improving the delay resolution in the time dimension from the transmitter to the receiver,so that the search time in the time dimension can be longer.The simulation results show that the improved algorithm makes the results of Doppler parameter estimation more accurate,and can improve the estimation accuracy of other parameters through the improvement of Doppler parameter estimation accuracy in the whole parameter subset,so as to improve the estimation accuracy of the whole estimation iteration process. |
