Arithmetic Research Of Channel Estimation And Suppressing Co-channel Interference In DTMB System Of Multi-carrier Mode

Digital Television Terrestrial Broadcasting is recently one of hot areas in wireless domain. It represents the developing precursor of broadband digital communication, breeds a opportunity to create a new market for mobile TV, and has bright future.The Chinese digital terrestrial television broadcasting standard with independent intellectual property ,named "Frame structure, channel coding and modulation for digital television terrestrial broadcasting system" was published, which stands for DTMB in english. Therefore,research on terrestrial transmission technique acording to digital television standard of our country has far-reaching meaning.Based on the analysis of the current development of digital television, this thesis on the basis of studying multi-carrier model in DTMB standard, in-depthly researchs TDS-OFDM's frame structure , analyses and researchs the system DTMB demodulator technology from following aspects.Firstly, the thesis discusses two DTMB standard channel estimation algorithms. One is the PN cycle correlation algorithm in time domain based on PN self-correlation characteristic.Aother is SO-NLMS channel estimation algorithm improved from LMS channel estimation algorithm.In this paper, these two algorithms are carried out a detailed performance simulation and analysis, which shows that both have higher estimation accuracy and lower hardware complexity, but the PN cycle correlation algorithm only suitable for channel whose delay is not more than 165 samples, and is not fit for dual-mode DTMB structure .But SO-NLMS channel estimation algorithm is fit for all delay length channel, and can act as the channel estimation algorithm used in a dual-mode DTMB structure.Secondly, Based on TDS-OFDM's frame structure's characteristic,The article discusses the frequency domain equalization algorithm.It through the data frame cycle reconstruction , realizes one tap equalization in frequency domain,and simulation proves their validity .Thirdly, on the basis of describing china's current analogue television system PAL format's principles and characteristics, the paper builds the PAL-D format's analog television signal platform, and gives the simulation results and analysis, which full verify the accuracy of platform structures, and also provides a good reference for other signal source platform structures such as NTSC.Finally, after careful analysing the characteristic of interference ,which is analogue televison added to digital television signal, a algorithm which full-scanning in capturing stage, segment detection and dynamic suppress CCI in tracking stage is provided. The paper detaily studies and analyses the principle and realization of the CCI suppress algorithm.The performance simulation showed that this method can not only reduce the analog PAL signal co-channel interference to the TDS-OFDM signal in the frequency, but also significantly reduces the volume of computing and hardware resources. In addition, the algorithm is also applicable to other similar OFDM transmission system.