Research On ISI Elimination Techniques For SC-FTN

The influence of wireless mobile communication on people's lives and economy is more and more obvious,but the shortage of spectrum resources is still an unresolved issue at present.The Fast-Than-Nyquist(FTN)transmission technology has a higher data transmission rate than the Nyquist transmission technology,effectively improving the system capacity and spectrum efficiency.However,FTN transmission inevitably introduces inter-symbol interference,which has an impact on performance of the system's bit error rate.Therefore,this thesis mainly studies the FTN interference cancellation from the perspective of equalization technology.First of all,this thesis gives a detailed introduction to FTN transmission related technologies,which including the differences between FTN transmission and Nyquist criteria and the advantages of FTN transmission in terms of system capacity and frequency band utilization,and analyzing the detailed process of FTN signal shaping and the degree of inter-symbol interference introduced by FTN under different parameters.For the inter-symbol interference introduced by FTN,three common equalization techniques are introduced.Secondly,in order to eliminate the interference introduced in FTN transmission,this thesis studies FTN frequency domain equalization technology,performs simulation analysis under different parameters and channel conditions,and conducts in-depth research on the current mainstream iterative algorithm based on Turbo equalization and the equalization algorithm based on noise prediction.In view of the problem that the latter suffers from performance loss due to error transmission during the equalization process,this thesis proposes an iterative equalization algorithm which introduces relevant factors by considering the error factor,and combines the idea of Turbo equalization to use the soft decision information output by the equalizer and decoder to iteratively update the filter,so that the equalizer can better eliminate Interference in FTN system.Theoretical analysis and simulation experiments prove that the proposed iterative equalization algorithm can effectively reduce the system bit error rate.Finally,in order to solve the problem of high complexity in the interference cancellation technology of FTN system,this thesis deeply studies the classical Iterative Block Decision Feedback Equalization(IBDFE)and low complexity IBDFE-X algorithm.On this basis,this thesis proposes an improved IBDFE-L algorithm which main idea is to estimate and eliminate residual inter-symbol interference in the output signal of the IBDFE-X equalizer,so as to achieve the purpose of further eliminating interference.Simulation results show that the performance of the proposed algorithm is significantly improved compared with the original algorithm;the complexity of the equalizer coefficient is slightly higher than the original algorithm but lower than the classic algorithm.At the same time,this thesis compares the performance and complexity of the two proposed algorithms.The results show that the proposed iterative algorithm is superior to the IBDFE-L algorithm in terms of performance,but it has a relatively high complexity.Therefore,according to different communication requirements,a more suitable algorithm can be selected from the two algorithms proposed in this thesis.