基于Simulink的16QAM调制解调及性能分析
摘要
随着无线通信频带日趋紧张，研究和设计自适应信道调制技术体制是建立宽带移动通信网络的关键技术之一。正交振幅调制技术（QAM）是一种功率和带宽相对高效的信道调制技术,因此在大容量数字微波通信系统、有线电视网络高速数据传输、卫星通信系统等领域得到了广泛应用。在移动通信中，随着微蜂窝和微微蜂窝的出现，使得信道传输特性发生了很大变化。过去在传统蜂窝系统中不能应用的正交振幅调制也引起了人们的重视。
本文首先简单简绍了QAM调制解调系统和MATLAB7.0/Simulink的工作原理。然后利用Simulink对16QAM调制系统进行仿真,不但得到了信号在加噪前后的星座图、眼图，而且在信噪比变化条件下,得到了16QAM系统的误码率。最后，在简单做了一个2DPSK系统仿真之后，将它与16QAM系统进行了比较，并得出了16QAM是一种相对优越的调制解调系统这一结论。
关键词：QAM SIMULINK; 仿真 ;2DPSK; 误码率
ABSTRACT
The research and design of adaptable channel modulation system is one of the key techniques in building a broadband mobile communication network with increasing shortage of wireless communication frequency-band. Because quadrature amplitude modulation (QAM) is efficient in power and bandwidth, it has been used widely in field of large-capacity digital microwave communication systems, high-speed data transmission cable television network and satellite communications.In mobile communications, with the appearance of micro-and pico-cell,channel transmission characteristics have made great changes. The quadrature amplitude modulation which can not be applied to the traditional cellular systems in the past has also attracted much attention.
This article briefly introduce how QAM modulation and demodulation system and MATLAB7.9/Simulink4.0 works. After a simulation of the 16QAM modulation system, we not only get the the signal constellation before and after adding noise, eye pattern, but also the BER with the changing conditions in the SNR. Finally, after a simple simulation of 2DPSK system,we made a comparition with the 16QAM system and get a conclusion that 16QAM is a relatively superior modulation and demodulation system.
Keywords: QAM ; Simulink ; Simulation ; 2DPSK ; BER
目录
1 绪论 1
1.1 ＱＡＭ简介 1
1.2 SIMULINK 2
1.3 SIMULINK与通信仿真 2
2 正交振幅调制 3
2.1 二进制解调 3
2.2 多进制解调 4
2.3 MQAM的原理 5
2.4 QAM的调制解调原理 8
3 SIMULINK 10
3.1 SMULINK简介 10
3.2 Simulink基本模块库介绍 10
3.2.1 Simulink的启动 10
3.2.2 Simulink的基本模块库介绍 11
3.2.3 Simulink简单模型的建立 13
3.2.4 Simulink 的Communications Blockset 14
4 16QAM调制解调系统实现与仿真 16
4.1 16QAM 调制模块的模型建立与仿真 18
4.1.1 信号源 18
4.1.2 串并转换模块 18
4.1.3 2/4电平转换模块 20
4.1.4 正余弦信号发生器 22
4.1.5 离散时间信号发散图示波器 22
4.1.6 调制系统的实现 23
4.2 16QAM解调模块的模型建立与仿真 24
4.2.1 相干解调 24
4.2.2 4/2电平判决 26
4.2.3 并串转换 28
4.2.4 其它模块 28
5 16QAM抗噪声性能研究 30
5.1 16QAM抗噪声性能仿真 31
5.2 16QAM与2DPSK系统抗噪声性能比较 32
总结 35
谢辞 36
参考文献 37
