Research Of Channel Estimation In OFDM System

Rapid modern mobile communication technology has brought tremendous changes about thedevelopment of human life. With the changes in lifestyle, people’s requirements for communicationquality is more and more high and improving the communication system performance is along-term subject for researchers. This thesis take the OFDM System for an example to havein-depth research about channelestimation algorithms.OFDM is currently the most promising multi-carrier transmission scheme and has been widelyused due to the efficient spectrum utilization and data transmission efficiency brought by itself. Inthe OFDM system, each channel is divided into a number of orthogonal subchannels, oneHigh-speed data signal is converted into parallel low-speed sub-data streams which will bemodulated and then transmitted on each subchannel, it is orthogonal between the respective signals.Through this method the mutual interference between those subchannels will be reduced. Nowadays,OFDM technology is widely used in the broadcast of audio, video field and civiliancommunications systems.According to the characteristics of wireless communication channel and OFDM system, thispaper focused on the research of Pilot-based channel estimation, and also introduced thecharacteristics of the associated pilot. The research contains the In-depth analysis of channelestimations criteria: LS,MMSE and SVD estimation. Athreshold is introduced in the LS algorithmjudgment method and the simulation results prove that the accuracy can be improved. In addition,there are several estimation methods for the non-pilot point: Polynomial interpolation estimation,DFT algorithm and Wiener filtering algorithm. The core technology MIMO-OFDM technology isadopted in the LTE system, and its performance is better than the previous system. It is also theimportant research content in this thesis. In the LTE uplink,combinating with MatLab, theperformance of channel estimation has been verified. At the same time, the simulation results in theLTE system were briefly analyzed.