Description: MQAM调制方式
本文主要介绍了正交幅度调制(QAM)调制和解调的原理和实现，MQAM与OFDM，MPSK的性能比较，以及MQAM在有扰信道下的性能及其改进方法：信道编码和频域均衡。并在已知特性的通信信道上进行仿-MQAM modulation This paper mainly introduces the quadrature amplitude modulation (QAM) modulation and demodulation principle and realize, MQAM with OFDM, MPSK Performance Comparison, as well as MQAM in Scrambling channel performance and its improvement: channel coding and frequency domain balanced. And characteristics of the communication channel known for imitation Platform: |
Size: 5120 |
Author:luobin |
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Description: WLAN仿真－发送机
wlan No Comments
设置完系统参数后，开始产生发送数据。
1. 产生随机的发送bit（tx_bits），这里不考虑信道编码。
2. QAM映射
3. 将数据映射到不同载波，形成OFDM符号
4. 产生pilot，并将pilot插入OFDM符号中
5. 加入dc和guard子载波
6. 进行ifft，将频域信号变到时域，并加入循环前缀
7. 对信号进行overlap window
8. 在时域产生short preamble
9. 在时域产生long preamble
10. 将preamble和数据符号组成packet
11. 升采样
得到信道传输的数据Tx_signal_up
具体程序见附件 wlan_transmitter.m-WLAN Simulation- wlan No Comments transmitter system parameters set finished, the beginning to have to send data. 1. Have sent random bit (tx_bits), here does not consider channel coding. 2. QAM mapping 3. The data is mapped to a different carrier to form OFDM symbols 4. Have a pilot, and pilot inserted OFDM symbols 5. Adding dc and guard subcarriers 6. To carry out ifft, will change the frequency domain signal to time domain, and add cyclic prefix 7. the signals overlap window8. In the time domain have a short preamble9. In the time domain have a long preamble10. the preamble and data symbols packet11. or sampling received data transmission channel Tx_signal_up specific procedures see Annex wlan_transmitter.m Platform: |
Size: 1024 |
Author:福东方 |
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Description: DMT调制，就是把整个通信信道在频域上划分很多子信道，在每个子信道上仍然采用QAM或类似的带通信号进行传输。其中QAM的通带中心频率应该与相应的子信道的中心频率一致。-DMT modulation, that is, the entire communication channel in the frequency domain divided on a lot of channel in each channel is still used on QAM or similar bandpass signal transmission. QAM one of the passband center frequency of the channel should be with the corresponding line of the center frequency. Platform: |
Size: 1024 |
Author:看看 |
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Description: 通信系统与仿真作业：
1）设计π/4-DPSK或16-QAM调制器仿真程序， 画出时域波形、 正交分量、同相分量波形，眼图，散点图等。
2）利用MATLAB进行DPSK在高斯信道下的BER性能仿真，并将结果与PSK性能进行比较。
3）已知 OFDM的数据传输速率为19.2Kbps， OFDM 符号长度为320，保护间隔为32点，子载波数为128，IFFT/FFT点数为256，载波频率320KHz，调制方案采用QPSK，仿真其在高斯信道下的BER性能。
-Communication systems and simulation tasks: 1) Design π/4-DPSK or 16-QAM modulator simulation program, draw time-domain waveform, quadrature component, in-phase component waveforms, eye diagrams, scatter plots, etc. 2) the use of MATLAB for DPSK in AWGN channel BER performance simulation, and the results are compared with PSK performance. 3) the known OFDM data transmission rate of 19.2Kbps, OFDM symbol length is 320, the guard interval is 32 points, the number of sub-carriers 128, IFFT/FFT points is 256, the carrier frequency is 320KHz, using the modulation scheme QPSK, simulation of the in Gaussian channel BER performance. Platform: |
Size: 268288 |
Author:wander |
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Description: 该程序基本涵盖了OFDM-16QAM系统传输的全过程，除了调制解调外，有添加循环前缀，加窗的过程。生成图像有各个阶段的时域、频域图，以及发射前后的星座图。-This basically covers the whole process of OFDM transmission- 16 qam system, in addition to the modem, have add cyclic prefix, plus the window procedure. Generate the image at various stages of time domain and frequency domain graph, and before and after the launch of the constellation diagram. Platform: |
Size: 5120 |
Author:刘晨 |
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Description: frequency division multiplexing (OFDM) is used extensively in broadband wired and wireless communication systems because it is an effective solution to intersymbol interference (ISI) caused by a dispersive channel. This becomes increasingly important as data rates increase to the point where, when conventional serial modulation schemes like quadrature amplitude modulation (QAM) or NRZ are used, the received signal at any time depends on multiple transmitted symbols. In this case the complexity of equalization in serial schemes which use time domain equalization rises rapidly. In contrast, the complexity of OFDM, and of systems using serial modulation and frequency domain equalization, scale well as data rates and dispersion increase. [1]–[3]. A second major advantage of OFDM is that it transfers the complexity of transmitters and receivers the analog to the digital domain-frequency division multiplexing (OFDM) is used extensively in broadband wired and wireless communication systems because it is an effective solution to intersymbol interference (ISI) caused by a dispersive channel. This becomes increasingly important as data rates increase to the point where, when conventional serial modulation schemes like quadrature amplitude modulation (QAM) or NRZ are used, the received signal at any time depends on multiple transmitted symbols. In this case the complexity of equalization in serial schemes which use time domain equalization rises rapidly. In contrast, the complexity of OFDM, and of systems using serial modulation and frequency domain equalization, scale well as data rates and dispersion increase. [1]–[3]. A second major advantage of OFDM is that it transfers the complexity of transmitters and receivers the analog to the digital domain Platform: |
Size: 415744 |
Author:kartick |
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Description: ofdm仿真，用matlab仿真实现ofdm，为初学者提供一条道路(The proposed secret data embedding and extraction in
OFDM is shown in figure 1.In order to achieve higher data
rate, the serial data stream bits are converted in to parallel data
output bits. Then the modulation schemes can be BPSK,
QPSK or QAM, which in turn assigns the complex data
points. The orthogonality between subcarriers is maintained
by IFFT and FFT pairs which also transforms frequency
domain components to time domain and vice versa. 64 point
IFFT is used in this methodology.) Platform: |
Size: 30720 |
Author:haitao15 |
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Search - qam IN frequency domain