Research On Faster-than-Nyquist Transmission Technology

In recent years,with the growth of the mobile business,spectrum resources are becoming increasingly scarce.People need to study transmission technologies with higher spectral efficiency,therefore,the Faster-than-Nyquist(FTN)transmission technology proposed in the1970 s has received renewed attention.FTN transmission is a transmission mode in which the symbol transmission rate is faster than the Nyquist symbol rate,Due to intersymbol interference(ISI)between FTN symbols,detection methods in traditional orthogonal transmission systems are no longer applicable.Therefore,the FTN transmission system needs to study a special algorithm to detect the received signal.Most of the FTN signal detection algorithms currently are suitable for the Additive white gaussian noise(AWGN)channel,therefore,this paper studies the FTN signal detection method for Rician channel firstly.At the same time,because of the timevarying characteristics of wireless channel,This paper also studies the adaptive transmission technology based on FTN transmission system,and a set of spectrally continuous variable adaptive transmission scheme design method has been obtained.The work accomplished by this paper mainly includes the following aspects:This paper introduced the history,system model and related concepts such as Mazo Limit of FTN transmission technology firstly.Then comparing the FTN signal with the orthogonal transmission signal from the perspective of capacity and peak-to-average ratio,it is concluded that when the pulse shaping waveform is not a sinc waveform,the capacity of the FTN signal will be larger than the capacity of the orthogonal modulation system.At the same time,from the simulation results of the peak-to-average ratio,it is found that when the rolloff factor of the pulse shaping waveform is greater than a certain value,The peak-to-average ratio of the FTN signal will be less than the orthogonal signal with the same spectral efficiency.This paper also studied two existing FTN signal detection algorithms,verified its performance through simulation,and analyzed the advantages and disadvantages of the two algorithms.For the research of the detection method for rice fading channels,This paper first analyzes the FTN signal observation model after rician fading channel.According to this model,the detection method for AWGN channel is revised,and a FTN signal detection method for Rice fading channel is proposed.Using the proposed detection method in the actual simulation,according to the simulation results,we can see that using the detection algorithm proposed in this paper,when proportion of energy in main path is greater than a certain value,the ber performance of FTN transmission technology will be better than orthogonal transmission system with the equivalent spectrum efficiency.For the research of adaptive transmission technology,this paper first studies a new FTN transmission system based on superposition coding.Then proposed an adaptive transmission scheme based on the system.Different from the traditional adaptive coded modulation technology,the proposed scheme achieves adaptive transmission by changing the number of superimposed layers and the transmission rate of each layer.The simulation results show that the adaptive transmission scheme obtained by using the design method presented in this paper has the capability of approximating the constrained capacity of the orthogonal system.It is sometimes even better than quadrature system constrained capacity.At the same time,this paper also proposes a method to filter adaptive alternatives by calculating estimated performance.The actual simulation shows that the proposed method has high accuracy.