超奈奎斯特信号关键技术研究

发布时间：2018-06-11 22:53

本文选题：超奈奎斯特信号 + 最小相位系统　；参考：《电子科技大学》2017年硕士论文

【摘要】：超奈奎斯特(Faster Than Nyquist,FTN)信号是指符号速率超越奈奎斯特速率的信号。相比于奈奎斯特信号,FTN信号具有更高的频带利用率。但是FTN调制符号传输时引入了符号间串扰,使得接收机设计复杂度提升。理论证明,在特定成型滤波器的前提下,当符号速率保持在一定范围内,仍能保证系统的性能。由于FTN信号发射端引入的串扰使发送符号之间具有了相关性,对于接收机的设计需要消除符号间的相关性才能正确接收。通信系统中抵消串扰常用的方法是信道均衡,其中包括在时域上利用非线性优化的最大似然序列检测算法或最大后验概率算法,以及时域和频域上的线性均衡算法等。同时,在多径信道下时,将FTN信号产生的冲击响应与信道冲击响应共同等效成整体信道冲击响应。基于FTN信号在时域上的相关性,将卷积编码器和交织器共同应用于FTN信号中,使该系统成为级联卷积码系统。当FTN应用于多载波系统中时,接收端通过在频域上处理来消除FTN信号自身的码间串扰。本文主要针对FTN信号的接收机进行设计优化。论文首先阐述了课题的研究背景及意义,将单载波传输和多载波传输分别与FTN信号进行结合。在保证带宽不变的前提下进行时域上的压缩,实现系统频带利用率的提升。下面简单概括一下本文的研究内容以及结构安排。第二章:本章主要研究单载波超奈奎斯特信号以及基于最大似然序列检测和最大后验概率的时域优化接收机的设计。通过分析最小相位系统和超级最小相位系统的特点和应用,实现了单载波FTN时域优化接收机复杂度的降低。另外,当系统对复杂度要求不高时,在时频域下针对FTN信号进行线性接收机的设计,其中在频域上的线性接收机等同于单载波频域均衡系统处理。最后,对FTN信号进行卷积编码,将该系统看成串行级联卷积码系统,并且通过基于最大后验概率的BCJR算法进行迭代译码。第三章:本章主要研究正交频分复用系统与FTN信号的结合,发射机的实现通过快速傅里叶逆变换后的时域信号再进行FTN调制。正交频分复用FTN信号经过多径信道时,利用基于导频的信道估计对系统整体信道冲击响应进行估计。接收端通过复杂度低的频域均衡技术对该信号进行接收。第四章:本章主要研究滤波器组多载波系统与FTN信号的结合。首先,介绍了基于快速傅里叶变换的正交频分复用/偏移正交幅度调制系统的原理及实现。通过使用一种时频聚焦性较好的滤波器,实现了该系统发射端无需加循环前缀就能使接收机正确接收。由于基于快速傅里叶变换的正交频分复用/偏移正交幅度调制系统中用到了滤波器组,因此该系统又被称为滤波器组多载波。另外,在复数信道多径衰落信道下的滤波器组多载波FTN系统中,通过基于导频功率最大化的干扰利用信道估计算法进行信道估计,最终利用频域均衡来设计接收机。第五章:本章总结了论文主要研究内容。针对目前FTN信号解调的问题,指出新的研究建议。
[Abstract]:The ultra Nyquist (Faster Than Nyquist, FTN) signal is the signal that the symbol rate exceeds the Nyquist rate. Compared to the Nyquist signal, the FTN signal has a higher frequency band utilization. However, the FTN modulation symbol transmission introduces intersymbol crosstalk to make the receiver design the complex degree of heterozygosity. On the premise, when the symbol rate is kept in a certain range, the performance of the system can still be guaranteed. Because the crosstalk introduced by the FTN signal transmitter has the correlation between the sending symbols, it is necessary to eliminate the correlation between the symbols for the design of the receiver. The common method of counteracting crosstalk in the communication system is channel equalization, The maximum likelihood sequence detection algorithm or the maximum a posteriori algorithm, and the linear equilibrium algorithm in time domain and frequency domain are used in the time domain. At the same time, the impact response of the FTN signal and the channel impact response are equivalent to the overall channel impact response in the multipath channel. The FTN signal is in the time domain on the time domain. The convolution encoder and interleaver are applied to the FTN signal to make the system a cascade convolutional code system. When FTN is used in multi carrier systems, the receiver eliminates the Intercode crosstalk of the FTN signal itself in the frequency domain. This paper focuses on the design and optimization of the receiver of the FTN signal. The paper first expounds the design of the receiver. The research background and significance of the subject, single carrier transmission and multi carrier transmission are combined with FTN signals respectively. In the premise of ensuring the constant bandwidth, the time domain compression is carried out to achieve the enhancement of the utilization of the system frequency band. The following is a brief summary of the research content and structure arrangement in this paper. Chapter second: this chapter mainly studies single carrier. Super Nyquist signal and the design of time domain optimization receiver based on maximum likelihood sequence detection and maximum a posteriori probability. By analyzing the characteristics and applications of the minimum phase system and the super minimum phase system, the complexity of the single carrier FTN time domain optimization receiver is reduced. A linear receiver is designed for the FTN signal in the frequency domain, in which the linear receiver in the frequency domain is equivalent to the single carrier frequency domain equalization system. Finally, the FTN signal is convoluted, and the system is read into a cascade concatenated convolutional code system, and the iterative decoding is carried out by the BCJR algorithm based on the maximum posterior probability. The third chapter: The chapter mainly studies the combination of the orthogonal frequency division multiplexing system and the FTN signal. The realization of the transmitter is realized by FTN modulation by the fast Fourier transform time domain signal. When the orthogonal frequency division multiplexing FTN signal passes through the multipath channel, the channel estimation based on the pilot is used to estimate the overall channel impact response of the system. The receiver passes through the complexity. The low frequency domain equalization technology receives the signal. The fourth chapter: this chapter mainly studies the combination of the filter group multi carrier system and the FTN signal. First, the principle and implementation of the orthogonal frequency division multiplexing / offset quadrature amplitude modulation system based on fast Fourier transform are introduced. The receiver can receive the receiver correctly without a cyclic prefix. Because the filter banks are used in the orthogonal frequency division multiplexing / offset modulation system based on the fast Fourier transform, the system is also called the multi carrier of the filter bank. In addition, the filter group multi carrier in the multipath multipath fading channel is used. In FTN system, channel estimation is carried out by channel estimation algorithm based on the maximization of pilot power, and the receiver is designed by frequency domain equalization. Chapter fifth: this chapter summarizes the main research contents of the thesis. In view of the current problem of FTN signal demodulation, the new research proposals are pointed out.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN911

【相似文献】