Application Research Of FTN Transmission System Based On Constellation Shaping

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 constellation shaping modulation.Firstly,this thesis introduces the background,current situation and basic theory of FTN transmission technology,analyzes the difference between Nyquist transmission and FTN transmission,deduces and verifies the classic Mazo bound,and analyzes the bit error characteristics of FTN transmission system through simulation.Then this thesis introduces constellation shaping modulation techniques that include probabilistic shaping and geometric shaping,describes the basic principles and characteristics of these constellation shaping modulation techniques.Secondly,in order to eliminate the interference introduced in FTN transmission,this thesis studies the constellation shaping modulation technique.Starting from the basis of information theory,describe the basic principles,implementation schemes and specific effects of constellation probabilistic shaping.Then,the constellation probabilistic shaping modulation technique is applied to the FTN system,and the simulation results are given,which are compared with the results using the traditional modulation technique.In addition,a probabilistic factor optimization algorithm based on probabilistic shaping and FTN transmission technology is proposed.Through this algorithm,the optimal probabilistic factor that meets the accuracy requirements can be obtained when the acceleration factor is fixed.Based on the optimal probability factor,accurate bit-error rate and signal-to-noise gain can be obtained,thereby better reflecting the performance optimization effect of the probabilistic shaping technology on the FTN transmission system.Finally,based on the carrierless Amplitude/Phase modulation technique,a new probabilistic-geometric hybrid constellation model is designed by optimizing and combining the constellation probabilistic shaping technique and the geometric shaping technique.The hybrid shaping technology is applied to the FTN transmission system,compared with the probabilistic shaping technology and the geometric shaping technology,and the simulation results are given,which preliminarily reflect the superior performance of the hybrid shaping technology.In addition,a probabilistic factor optimization algorithm is used to obtain the optimal probabilistic shaping factor that meets the accuracy requirements when the acceleration factor is fixed.Based on the optimal probabilistic shaping factor,the bit error rate and signal-to-noise are used as parameters to better compare the performance optimization effects of several constellation shaping modulation techniques mentioned in this thesis on the FTN transmission system,and clearly demonstrate the superior performance of the new probabilistic-geometric hybrid constellation model.Through the simulation analysis,it is proved that the FTN transmission system can reduce the additional inter-symbol interference and improve the system bit error rate performance while improving the spectrum utilization by using the probabilistic shaping technology or the geometric shaping technology.