OFDM-based Digital TV Terrestrial Channel Estimation Study

In recent years, the pace of development of digital television technology faster.In the next few years, digital TV will completely replace analogue television, becomea strong new pillar industries. Abroad are now the dominant standard: EuropeanDVB-T, ATSC US and Japan ISDB-T. China’s digital TV standard has its own history,our country in2006, China formally proposed terrestrial digital TV transmissionstandard (DTMB), which is a milestone in China’s digital TV transmission standard,in GB in orthogonal frequency division multiplexing for conduct a detaileddescription.Field OFDM technology more widely, its high-speed wireless data transmissionis a relatively large advantage, with a very large market. Meanwhile, OFDMtechnology, anti-interference ability, utilization of broadband is relatively high, it willbecome a low-speed data streams from high-speed, low-speed data stream tooverlapping or orthogonal form. For multipath fading, OFDM also has a very strongresistance.In this paper, the wireless channel characteristics are analyzed includingmulti-path interference and Doppler frequency shift etc. The channel estimationalgorithms based on using pilot signal are analyzed, a named SVD algorithm withlower complexty and better performance is specially shown and pointed for practicalapplication. For DTMB system based on using known PN as guard interval, a newadaptive channel estimation method is presented by using time-variable step sizeaccording to variable channel coefficients. The new adaptive channel estimationmethod is with lower complexity and better performance compared with usingtraditional Doppler frequency estimation method.This article needs to do the main work is: For digital TV standard and abroad tohave a comprehensive understanding of where, for China’s digital TV standard, youneed to understand the overall structure, the basic framework of the sender and thereceiver, the signal transmission side and what treatment, at the receiving end of what treatment, the role of the linkages between functional modules and each module musthave a comprehensive understanding. Meanwhile, for orthogonal frequency divisionmultiplexing channels common algorithms were compared by MATLAB simulation,analysis of the comparative advantages and disadvantages of the three algorithmsbased on using pilot signal. The presented new DTMB adaptive channel estimationmethod is described as well.