Study Of Channel Estimation In Terrestrail Digital TV Transmission System

Presently three terrestrial broadcasting standards have been proposed: ATSC (U.S.A) based on 8-VSB single carrier technique, DVB-T(Europe) and ISDB-T (Japan) based on OFDM multicarrier technique. But all of them have their own advantage and disadvantage. The problem of how to design a steady receiver for the complicated terrestrial channel is still the basic technical difficulty and research focus of the DTTB system. This dissertation focuses on the digital inner receiver techniques on the background of DMB-T proposed by Tsinghua University as a new DTV transmission scheme. With deep study of the exist inner receiver algorithms for DTTB, and the research experience of digital communication techniques, frequency synchronization, channel compensation and phase noise reduction.First, the features of terrestrial digital TV transmission standards in and abroad , have introduced , and Time Domain Synchronous-Orthogonal Frequency Division Multiplexing (TDS-OFDM) system structure has been explained. Connecting OFDM and Spread frequency -communication , using PN for timing synchronization , including frame synchronization, frequency synchronization, timing synchronization, channel estimation and tracing phase noise. Then the characters of the signal frame in standards and advantage have been proposed .Second, cyclic correlation algorithm based on PN sequences has been proposed. Instead of CP, PN sequences have been inserted to signal blocks by IDFT as guard interval. Without GI, ICI and ISI have existed, and using the cyclic correlation and iteration inference remove technology, channel impulse response has been estimated more exactly.Third, cyclic convolution algorithm has been proposed. Because DTTB system has worse condition, cyclic convolution and iteration inference remove have used to get more exact channel impulse response with long paths interference. Do some simulation using the algorithms , and results has been known. Then compared with the performance of the systems.Finally, in Chinese terrestrial digital TV transmission system using the new algorithms , the efficiency and the feasibility of algorithms have been aggregated. And next work will be continued to research.