摘要本文主要研究了3种正交幅度调制(Quadrature Amplitude Modulation, QAM)信号(16QAM、32QAM、64QAM)的调制方式识别与解调的问题，仿真了一种基于非协作通信的调制方式识别方法，并测量了解调误码率(Bit Error Ratio, BER)随信噪比(Signal-to-Noise Ratio, SNR)变化的曲线。本文所使用的方法无需知道载频、符号速率等先验信息，而是通过估计出的载频和符号速率对信号做下变频和定时处理。调制方式识别是利用信号的高阶累积量与最小环带的方差这两个特征，对残余频偏不敏感。基于Matlab的软件实现表明，在-15dB及以上信噪比下，调制方式识别错误率稳定在10%以下；16QAM、32QAM、64QAM的误码率分别在-9dB、-6dB、-2dB信噪比下达到10-3，系统性能达到实际非协作通信系统中QAM信号的识别和解调的要求。64587

毕业论文关键词：  非协作通信；参数估计；调制方式识别；QAM

毕业设计说明书（论文）外文摘要

Title         Modulation Recognition and Parameter   Estimation of QAM Signals               

Abstract

This thesis studies the problems of modulation recognition and demodulation of three typical MQAM (M-ary Quadrature Amplitude Modulation) signals (16QAM, 32QAM and 64QAM respectively). The simulation system realizes the QAM signal modulation recognition as well as demodulation, and the performance of the designed system is reflected by the probability of bit error. Instead of acquiring prior information such as the carrier frequency and symbol rate, down-conversion and timing synchronization are realized based on estimated parameters. High-order cumulants after calculus of differences and variance of the minimum ring are adopted as key features in modulation recognition, which insures that the modulation recognition is not sensitive to residual frequency offset. Implementation based on Matlab shows that the aforementioned three types of signals have been recognized with an average failure rate less than 10% at SNR (signal-to-noise ratio) greater than -15dB. Additionally, the BER (bit error rate) of 16QAM, 32QAM and 64QAM achieves 10-3 when SNR is -9dB,-6dB and -2dB, respectively. System performance has satisfied the requirements of signal recognition and demodulation in practical non-cooperation digital communication systems．

Keywords: non-cooperative communication; parameter estimation; modulation classification; QAM

1 引言 1

1.1 背景 1

1.2 目标 2

1.3 章节安排 2

2 信号的产生与预处理 2

2.1 信号模型 2

2.2 信号的产生 3

3 信号参数估计 5

3.1 预处理 5

3.1.1 带宽估计与载频粗估计 5

3.1.2 抽取降速 7

3.2 剩余载频精确估计 7

3.3 符号速率估计 8

3.4 匹配滤波