Research On Channel Estimation Of OFDM System And Its Application In DVB-T Standard

OFDM (Orthogonal Frequency Division Multiplexing) is originated from MCM (Multi-Carrier Multiplexing). It has been more and more concerned because of its high utilization of frequency spectrum and excellent capability of countering multi-path interference. With the development of DSP technique in these years, FFT technique could be used in reality. So OFDM technique has been applied popularly in many domains, such as DAB (Digital Audio Broadcasting), DVB (Digital Video Broadcasting), and WLAN (Wireless Local Area Network) and so on.The research of channel estimation in OFDM system can be conducted in two categories:One is based on blind channel estimation, the other is channel estimation based on pilots. Because of the high algorithm complexity, the slow convergence and the signal or symbol obscure problem of the blind channel estimation, it is not suitable in practical use. So this paper focuses on the research of channel estimation based on pilots. After analyzing the common channel estimation algorithm and making some improvements, Laplas interpolation algorithm is introduced here, according to the special pilot scheme in the 2K mode of DVB-T system, we propose a two dimension with time and frequency union channel estimation algorithm. It is proved to be lower algorithm complexity and lower BER compared to one dimension channel estimation.In this paper, the development and application background of OFDM technique and the research status of the channel estimation in OFDM system are introduced firstly, and the research significance of this thesis is pointed. Then the basic principle of OFDM system is discussed, and the characteristics of the wireless channel and the model of OFDM system are introduced in detail. In the channel estimation chapter, I research and simulate several channel algorithms and interpolation algorithms. Further the thesis mainly researches the application of channel estimation in the DVB-T system, and proposes the two dimension interpolation with time and frequency domain to the particular pilot distribution in DVB-T standard. It can obtain better performance with great BER improvement in BER through simulating with one dimension interpolation in frequency domain.