Research On The Key Techniques Of The Faster Than Nyquist Signaling

The faster than Nyquist(FTN)signaling is the symbol that rate goes beyond the Nyquist rate.Compared with the Nyquist signaling,FTN signaling has higher band utilization.but the modulated symbol transmission introduces the inter symbol interference,that makes the design complexity of the receiver is increased.The theory proves that under the premise of a particular forming filter,the performance of system can be ensured when the symbol rate is kept within a certain range.Due to the crosstalk introduced by the FTN signaling transmitter,there is a correlation between the transmitted symbols.the receiver design needs to eliminate the inter symbol interference between symbols.The method used to cancel crosstalk in communication systems is the channel equalization,which includes the use of non-linear optimization of the maximum likelihood sequence estimation algorithm or the maximum a posteriori algorithm in the time domain,As well as the time domain and the frequency domain on the linear equalization algorithm.At the same time,in the multipath channel,the overall channel impulse response is combined by the impact response that FTN signaling generated and the channel impulse response.Based on the correlation of the FTN signaling in time domain,convolutional encoder and interleaver are applied to FTN signaling,which makes the system to be a cascade convolutional code system.When the FTN signaling is applied to the multi-carrier system,the receiver can process in the frequency domain to eliminate the crosstalk of the FTN signaling.This paper focuses on designing the receiver of FTN signaling optimally.Firstly,this paper describes the research background and significance of the subject,The single-carrier transmission and multi-carrier transmission are combined with FTN signaling.In the time domain,data compression is performed on the premise that the bandwidth is constant,to realize the improvement of system frequency band utilization.The following part briefly summarizes the content and structure of this study.Chapter 2: This chapter mainly studies the design of single-carrier FTN signaling as well as the design of time domain optimization receiver based on maximum likelihood sequence detection and maximum a posteriori probability.By analyzing the minimum phase system and super minimum phase system,the single-carrier FTN time domain optimization receiver is reduced in complexity.In addition,when the complexity of the system is not demanding,the design of a linear receiver for FTN signaling is performed in the time-frequency domain,and the linear receiver on the frequency domain is equivalent to single carrier frequency domain equalization system processing.Finally,the FTN signaling is convolutionally encoded can be regarded as a serial concatenated convolutional code system,and it is decoded by the BCJR algorithm which based on the maximum a posteriori probability.Chapter 3: This chapter mainly researches the combination of orthogonal frequency division multiplexing system and FTN signaling,the implementation of the transmitter is that the time domain signal obtained by fast Fourier transform is modulated by FTN.When the orthogonal frequency division multiplexing FTN passes through the multipath channel,the channel impulse response of the system is estimated by pilot based channel estimation.The receiver receives this signaling through frequency domain equalization technique with low complexity.Chapter 4: This chapter focuses on the combination of filter bank multi-carrier system and FTN signaling.Firstly,the principle and implementation of orthogonal frequency division multiplexing/offset quadrature amplitude modulation system based on fast fourier transform is introduced.By using a time-frequency location better filter,to achieving this system transmitter can make the receiver correctly received without adding the circle prefix.Because of using the filter bank,the system is called the filter bank multi-carrier.In addition,the filter bank multi-carrier FTN system passes through a complex multipath channel,interference utilization channel estimation algorithm based on pilot power maximization is used to estimate the channel,and the receiver is designed by frequency domain equalization finally.Chapter 5: This chapter summarizes the main research contents of the thesis.In view of the current FTN signaling demodulation problem,the new research proposal is pointed out.