Research On Channel Estimation And Adaptive Technology In Orthogonal Frequency Division Multiplexing System

At present,we have gone into the time of the 4th generation communication(4G),and the researching of 4G communication technology is still hot.We hope to break through the key technologies of the 4G communication technology to better serve the community.The Orthogonal Frequency Division Multiplexing(OFDM),as one of the core technology in 4G system,is still being touted and never faded.Channel estimation and adaptive technology are two important aspects of the focus of researching on OFDM.The main studying of two parts is that it finds an algorithm which has good performance and low computational complexity.This paper is studied the basic implementation of OFDM,and through it as a research environment for channel estimation and the adaptive algorithm done testing research work of corresponding algorithm by Matlab simulation.In this paper,the main research work is as follows:(1)First,this paper introduces the mathematical implementation of OFDM and then a lot of its performance parameters are analyzed with programming by Matlab simulation,such as the 16QAM modulation,the impact of the superposition between Cyclic prefix and Loop suffix and adding window technology and so on.And it is laid the foundation for the next study.(2)In the study of the channel estimation,the paper starts from what the channel and its parameter is and then channel estimation method is introduced in detail.Here introduces several typical estimation algorithms:tunable filter method,the LS algorithm,MMSE algorithm and SVD algorithm.After the test simulation,this paper puts forward a method based on intelligent threshold.Through Matlab simulation obtained corresponding algorithm performance analysis,the results show that the method based on intelligent threshold is suitable for channel estimation?But it is restricted in fact,because it needs getting the state parameter in advance.(3)On the adaptive technology research,its study is going on.In this paper,the corresponding modulation algorithms are done performance analysis by the Matlab simulation and the main researched algorithms are:Ficsher algorithm,Chow algorithm and Hughes-Hatogs algorithm.And we learn the process that three kinds of algorithms change bit and power allocation with the channel gain change and three kinds of algorithms complexity increase in turn.This also laies the foundation for later research work and makes the direction.