Diversity Reception In Chinese DTTB

Implementing high bit rate mobile reception using single carrier mode in Chinese DTTB is a great technological breakthrough, but the performance of the single carrier system using time domain equalizer is disturbed by the channel fading greatly.This paper researches the existing terrestrial digital television broadcasting single carrier system and analyses the function and algorithm of the main module in the system, especially the equalizer. It gives an analysis and discussion of the equalization technology used in the system from the aspects of structure, sampling rate, convergence rule and the special overlapped structure. In the condition of dynamic frequency selective channel fading, the input SNR will decline significantly because of severe fading, and lead to serious error proliferation in the equalizer, thus limiting the equalizer performance. The simulation proves that the existing single carrier system using equalizer can’t combat the channel fading effectively and the performance bottleneck has been encountered. Therefore, enhancing the equalizer capability to combat channel fading is the key point in the designation of the single carrier receiver system.Diversity is an effective and necessary technology, making full use of the characteristic that multiple independent fading signals will have small chance to fade together, to combat channel fading and achieve diversity gain.Based on each characteristic of adaptive equalization and diversity, the paper focuses on how to make diversity technology in the existing system and introduces three equalization technologies combined with diversity. The technologies use diversity to improve the input SNR of equalizer in order to combat the possible severe fading, and use adaptive equalization to combat frequency selective fading. The paper gives detailed theoretical analysis and simulation results of them. By comparison, it can be seen that through introduction of diversity, the equalizer can restrain error proliferation and reduce SER when the channel fade severely. It eliminates the restriction of SER by the channel fading, and makes a breakthrough that in the high input SNR conditions, the SER can decline as the input SNR increases, improving the sensitivity of receiver significantly. The simulation results can prove the effectiveness and feasibility of these technologies.