高速移动信道的有关参数辨识的分析.docx

ABSTRACT
With the rapid development of munications, the urgent issue to be resolved is to improve the utilization rate of spectrum. However, MIMO is the key technology to solve this problem, which can greatly improve the utilization rate of spectrum and channel capacity. OFDM technology is based on the multi-carrier transmission. Under the condition of frequency-selective fading channel, since the simple MIMO system cannot ensure the good characteristics mentioned above, so its frequency-selective fading channel can be divided into several frequency-non-selective fading channels on the sub-carriers by using OFDM, and bination can realize the advantages of MIMO. This paper can be summarized as follows:
First, the source and significance of this study are given by analyzing the current status of research according to the development trends of the munication technology. Based on the characteristics of the wireless channel, the basic principles and system models of MIMO, OFDM, and MIMO-OFDM system are introduced respectively.
Then, The channel estimation under the frequency-non-selective and frequency-selective channel environments are mainly researched for MIMO system. First of all, the theoretical foundation of channel estimation is introduced briefly and the observation results are analyzed respectively by using LS, ML and MMSE algorithm. Then, the algorithm estimation under different channel environment is derived according to the applied training sequence, and the corresponding simulation results are given at the same time.
Finally, this paper studies the algorithm of carrier frequency offset estimation for MIMO-OFDM system which needs perfect estimation, because the loss of the orthogonality among sub-carriers can be caused by carrier frequency offset, which will reduce the system performance. As for the system with time-domain sequence, two sequences with different length are used to estimate algorithm based on the different phase offsets of the same training