Research On Channel Modeling And Channel Estimation For CMMB System

China Mobile Multimedia Broadcasting (CMMB) is the standard of the mobile TV industry in China, which adopts Orthogonal Frequency Division Multiplexing (OFDM) modulation technique. The basic principle of this technique is to convert high speed data stream into multiple parallel low speed data stream, which effectively reduces the inter-symbol interference and improves the spectrum utilization greatly.Channel modeling is to simulate the real propagation path of radio waves, and also an important way to study the influence that wireless channel has on the signal. While the channel estimation method at the receiver is to estimate the interference on the signal caused by the channel, and recover the original emission signal by compensating. Therefore, the channel modeling and channel estimation is of great significance.This thesis is organized as follows.1. Research on the current development of the mobile multimedia broadcasting standard at home and abroad. In addition, the CMMB system frame structure and the basic principles of OFDM modulation are introduced in detail.2. Analysis of the characteristics of wireless channel, including large-scale fading and small-scale fading. deduced the classic flat fading model., use both the shaping filter method and the sinusoidal wave superposition method to model and simulate the flat fading channel.Based on the TDL model, establish the Stanford University Interim frequency selective fading channel model.3.For the noise from channel and channel estimation, combined wavelet de-noising with channel estimation, first estimate the channel at pilot tones, and then process the frequency response using wavelet de-noising technique, finally use an efficient interpolation to get the whole channel frequency response. Based on two kinds of channel model, the simulation results are given to verify the good performance of the proposed algorithm under the environment of MATLAB.4. Using VS2013, measure and analyze the channel model and channel estimation algorithm studied in this thesis.