基于低量化比特的数字通信系统关键技术研究

发布时间：2018-02-28 13:03

本文关键词： 低量化比特数字接收机相位估计自动增益控制 dither　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：数字信号处理技术(DSP)是现代数字通信的核心,数字解调器比模拟解调器具有更高精度、更高的灵活性和稳定性,因此得到广泛的应用。但是随着数字信号的发展,数字模拟转换器(ADC)逐渐成为数字通信的限制因素。采样速率达到数Gsps的ADC并不多见,并且高速率且高精度的ADC的功耗非常大,不适合用于通信系统中的移动设备。然而经过研究表明,低精度量化是一种有效的解决方案。低精度量化尤其是1bit量化在超宽带通信中已经有着很多的研究和应用,但是在非超宽带的通信系统的研究中比较少见。本论文研究的主要内容是低精度的ADC在数字通信系统中的应用以及如何利用极少的量化比特(通常为1~4bit)实现数字信号的自动增益控制和载波相位偏移恢复。第二章对数字接收机受到低量化比特的影响进行了分析,主要是针对2-4比特下QPSK或16QAM的数字接收机,也包含了在系统有缓慢衰减,相位偏差或者符号定时误差,仿真结果显示当量化器的量化步长设置合理之时系统的性能是可以接受的。本文同时也对于数字接收机中的自动增益控制和相位估计进行的分析。第三章主要研究了QPSK数字接收机的中的相位估计在低量化比特条件下的影响。本章首先对不同相位估计算法在高量化噪声下的影响,同时本文给出了一中实用的相位估计器。自动增益控制是接收机中的一个重要部分,第四章首先对不同的自动增益控制算法进行了讨论和分析,然后通过对传统的自动增益控制进行了仿真并且分析了低量化比特下的自动增益控制的性能改变。Dither在很多领域中有着非常重要的作用,在模数转换中加入合适的dither信号可以提高有效精度。本文对ADC中的dither进行了讨论,同时也对相位估计中的dither进行了讨论。
[Abstract]:Digital signal processing (DSP) is the core of modern digital communication. Digital demodulator has higher precision, higher flexibility and stability than analog demodulator, so it is widely used. Digital to analog converter (DAC) is becoming the limiting factor of digital communication. ADC with sampling rate up to the number of Gsps is rare, and the power consumption of high speed and high precision ADC is very large. However, low precision quantization is an effective solution. Low precision quantization, especially 1bit quantization, has been studied and applied in UWB communication. However, the research of non-UWB communication system is rare. The main content of this thesis is the application of low-precision ADC in digital communication system and how to realize digital by using very few quantization bits (usually 1bit). The signal automatic gain control and carrier phase offset recovery. Chapter 2 analyzes the influence of low quantization bits on the digital receiver. Digital receivers for QPSK or 16QAM at 2-4 bits also include slow attenuation, phase deviations or symbol timing errors. The simulation results show that the performance of the system is acceptable when the quantizer's quantization step size is reasonable. This paper also analyzes the automatic gain control and phase estimation in the digital receiver. The influence of phase estimation in QPSK digital receiver under low quantization bit condition is investigated. Firstly, the effect of different phase estimation algorithms on high quantization noise is discussed. At the same time, a practical phase estimator is given in this paper. Automatic gain control is an important part of the receiver. Chapter 4th discusses and analyzes different automatic gain control algorithms. Then the traditional AGC is simulated and the performance change of AGC under low quantization bit is analyzed. Dither plays a very important role in many fields. The effective precision can be improved by adding appropriate dither signal to the analog-to-digital conversion. The dither in ADC and the dither in phase estimation are discussed in this paper.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN914.3

【参考文献】