Wireless-World-Initiative-New-Radia

matlab，QPSK,通信系统，调制，解调，信号波形，频谱(matlab, QPSK, the communication system, modulation, demodulation, the signal waveform, the spectrum)

虚拟串口工具，可以在普通电脑上虚拟成对串口，方便进行串口编程的本地调试(Virtual Serial Port Tool, which can be virtual paired serial ports on ordinary computers, facilitates the local debugging of serial port programming.)

接收端采用的算法和程序流程与发送端发送的OFDM符号的帧结构有关系。具体的帧结构，以及定时估计，频偏估计，剩余误差跟踪的算法可参考算法说明文档。这里对程序的流程进行说明。 首先根据短训练字的特性进行相关运算，进行信号到达检测，当检测到相关值大于门限一定次数后，认为有信号到达。然后根据长训练字的特性，进行相关运算，进行OFDM符号FFT窗口起始位置的估计。估计出FFT窗口的位置后，先在时域进行小频偏的估计，将两个长训练字进行小频偏补偿后，进行FFT运算，根据FFT运算的结果进行整数倍频偏的估计。这些参数估计完成后，就可以进行数据解调了。先对数据部分进行完整的频偏补偿，然后根据估计的FFT窗口位置进行FFT运算得到频域的数据，进行解调。然后在对应于导频的子载波位置上提取出导频信息，根据导频信息估计出剩余定时误差以及剩余的信道响应误差，将误差量送入环路进行跟踪。当收到所有数据后，重新回到信号到达检测状态，进行下一次信号到达的检测和信号接收。 (good)

基于MATLAB平台的通信系统的仿真，RS编码，OFDM调制，加入PLC信道噪声，并进行误码率的检测，运行无误，程序完整。(MATLAB-based communications system simulation platform, RS coding, OFDM modulation, adding PLC channel noise, and make BER testing, run correctly, the program integrity.)

说明：  主要包含BPSK信号产生，成形滤波，调制，加噪，下变频，解调(It mainly includes BPSK signal generation, shaping filtering, modulation, noise adding, down conversion and demodulation)

16QAM调制与解调程序，使用matlab运行(16QAM modulation and demodulation process, the use of matlab run)

很久很久之前，收藏的一份 清华大学 p2p相关的研究文献，希望对有需要的人有帮助，非常难得(Long, long ago, a collection of P2P-related research literature collected by Tsinghua University, hoping to help people in need, is very rare.)

说明：  WIRELESS CHANNEL MIMO

Multiple input multiple output techniques combined with orthogonal frequency division multiplexing (MIMO-OFDM) provide a promising approach for wireless systems. However, a serious drawback of the OFDM system is the high peak-toaverage power ratio (PAPR), which may severely affect the power efficiency of RF power amplifiers. In this paper, we propose a simple method to reduce the PAPR of MIMO-OFDM signals based on the use of unused subcarriers. Instead of processing the signals at each transmitter separately, a peak cancelling signal is generated at one antenna and is then applied to all the others with only simple modifications. Simulation has shown that a minimum 2 dB reduction in PAPR can be achieved for all transmit signals using this approach. As the signal processing is nearly all done at a single transmitter, repetition of the operations at each transmitter is avoided, and therefore the overall cost of the system can be significantly reduced.

Gardner位同步算法与锁相环的联合仿真程序.加入了时偏和频偏，能很好地锁定时偏和频偏，得到最佳采样输出。(Gardner bit synchronization algorithm and phase-locked loop joint simulation program, adding time offset and frequency offset, can well lock the bias and frequency offset, get the best sampling output.)