Research And Design Of Soft-decision Algorithm In The DFE

This subjectcomesfromthe China Digital Television Terrestrial Broadcasting Standard (DTMB) receiver of Shanghai BWAVE Technology Co.,Ltd. Hard decision algorithm used in the DFE design of DTMB receiver, which brings about serious error propagation phenomenon, affects the overall performance of the receiver. Compared with competitors, the DTMB receiver’s SNR performance in a particular channel has yet to be optimized. So it is necessary to find an appropriate soft-decision algorithm, effectively inhibit the DFE error propagation phenomenon, aimed at improving the overall performance of receiver. The main work of the paper are as follows:By the principle of a variety of soft-decision algorithm, algorithm designed for the DTMB receiver platform, simulation results show that a variety of soft decision algorithm on the receiver system SNR performance has improved to varying degrees, in the SCI12and SCI13mode, the best performance to improve the amount of0.3dB and0.2dB. Combination of algorithm and analysis of simulation results, important conclusions:No matter what kind of soft-decision algorithm, we must make use of the reliability information, only when the hard decision is not reliable, you can enable the soft-decision, otherwise it will cause more miscarriage of justice. Propose a decision mechanism, the use of reliability infonnation as a basis for decision, the verdict to the combination of the hard decision and soft decision. And performance simulation to verify the importance of reliability information, concluded that:how to get the reliability of the information is the key to improve performance. If you get the reliability information, then use this information, the soft decision algorithm will have a larger room for improvement of system performance.By analyzing the input distribution of decision device in the probability of decision under different decision threshold H, limited to the H value in a decision gate, the weighting algorithm can achieve optimal performance, which proposed the introduction of the decision threshold of the weighting algorithm.Compared with the hard decision algorithm, in the SCI12and SCI13mode, the system SNR performance of this algorithm to improve the amount of up to0.4dB.By analyzing the traditional weighting factor calculation method, the traditional two-dimensional calculation of improvement for the one-dimensional calculation, an improved weighting factor calculation method is proposed, which proposed the introduction of the weighted decision threshold algorithm improved algorithm. The performance simulation showed that, compared with hard decision algorithm, in the SCI12and SCI13mode, the improvement of system SNR performance of this algorithm is up to0.6dB and0.5dB, respectively. And the channel parameters change, the performance improvement is stable and continuous.In addition, the frequency domain equalizer of DTMB receiver also has a feedback judgments module,in which the soft decision algorithm of this research project can also be applied. Therefore, this study results has a guide on the application of equalizer, which has a feedback structure.