PTS

航空航天通信技术一般采用模拟通信的频率调制和数字通信的移相键控调制方法。这有利于充分应用信道带宽和能源。频率调制是在一定程度上改变载波或副载波的频率来传输信息的调制方法。移相键控调制是利用载波或副载波的相位跳变来传输信息的调制方法。移相键控又分二相移相键控、四相移相键控和多相移相键控，其中以四相移相键控和八相移相键控调制方法的效率较高(Aerospace communications technology commonly used analog communication of frequency modulation and the digital communication phase shift keying modulation method. This is helpful for making full use of channel bandwidth and energy. Frequency modulation is changed to some extent carrier or subcarrier frequency to transmit information modulation method. Phase shift keying modulation is the use of carrier or subcarrier phase jump to transmit information modulation method. Phase shift keying and binary phase shift keying, four phase shift keying and multiple phase shift keying, of which four phase shift keying and eight phase shift keying modulation method of high efficiency )

In recent years, the number of portable mobile terminal users is increasing with improvement of the wireless communication environment. In addition, mobile multimedia services also bring the increase of wireless traffic and lack of spectrum resources. As a technique for efficient spectrum use, spectrum sharing receives much attention. It dynamically assigns a spectrum channel from a larger area network such as WiMAX to smaller area networks such as WiFi-based wireless LANs and achieves to increase the total wireless communication capacity of this area. In a case where all providers are cooperative, the spectrum sharing can be realized easily and improve user throughput in average. In another case where providers are not cooperative, some spectrum trading methods based on auction theory had been proposed.

6e协议中移动WiMAX的AMC方案，仿真UGS业务在不同到达率下的吞吐率，丢包率、仿真时间内总能耗、千比特能量消耗(6e protocol in mobile WiMAX AMC scheme)

Matlab in German Course

说明：  6. 在三条径的瑞利信道中，对于OFDM： (1) 请设计一种具体的导引辅助的信道估计方法，用Simulink进行仿真。画出比特信噪比与信道估计均方误差的关系曲线和比特信噪比与误码率的关系曲线。 (2) 设频率已同步，请设计OFDM一种具体的采用循环前缀进行时间同步方法，用Simulink进行仿真，画出比特信噪比与捕获概率的关系曲线。 (3) 设时间已同步，请设计OFDM一种具体的采用循环前缀进行频率同步方法，用Simulink进行仿真，画出比特信噪比与频率同步误差的关系曲线。(6. In the three-path Rayleigh channel, for OFDM: (1) please design a specific navigation-assisted channel estimation method and use Simulink for simulation.The relation curves of bit signal-noise ratio and channel estimation mean square error and the relation curves of bit signal-noise ratio and bit error rate are drawn. (2) if the frequency has been synchronized, please design a specific method of time synchronization using cyclic prefix in OFDM. Simulink is used for simulation to draw the relationship curve between bit-snr and acquisition probability. (3) if time has been synchronized, please design a specific method of frequency synchronization using cyclic prefix in OFDM. Simulink is used for simulation to draw the relationship curve between bit signal-to-noise ratio and frequency synchronization error.)

几个关于MIMO雷达的仿真程序，对学习相关内容的人有些帮助。(Several of the simulation program about MIMO radar to the study of relevant content people some help.)

简单地绘制BOC（1, 1）调制信号的功率谱密度及其自相关函数曲线，仅供参考。(Simple drawing BOC (1, 1) density and autocorrelation function curve of power spectrum of the signal modulation, for reference only.)

不错的客户端连接程序，希望大家喜欢，里面是一个客户端的程序，一会会提供服务端的程序(good client procedures in the hope that everyone likes, there is a client process, will provide a service side of the process)

OPNET14.5的帮助文档，几乎所有的现行阶段的教材都是由该软件帮助文档改编或缩减而成，所以该文档为OPNET学习者必备手册之一。(OPNET14.5 the help of documents, almost all of the current phase of the teaching materials are adapted to the software help files or reduced form, so the document must have the manual for one of OPNET learners.)

1）设计Butterworth型音频抗混叠滤波器； 2）参数： 下通带频率300Hz；上通带频率3400Hz； 下阻带频率280Hz；上阻带频率3600Hz； 通带最大衰减0.3dB； 阻带最小衰减40dB； 3）采用一低通滤波器和一高通滤波器级联； 4）分别确定LPF和HPF的性能指标； 5）求出两滤波器的系统函数和频率响应，并画出其幅频特性曲线； 6）求整个滤波器的系统函数和频率响应，并画出其幅频特性曲线。(1) the design of Butterworth-type audio anti-aliasing filter 2) parameters: passband frequency of 300Hz on pass-band frequency 3400Hz under the stop-band frequency of 280Hz on stop-band frequency 3600Hz passband maximum attenuation of 0.3dB minimum stopband attenuation of 40dB 3) the use of a low-pass filter and a high-pass filter cascade 4) separately to determine the performance of LPF and HPF target 5) to derive two-filter system function and frequency response, and draw its increase frequency characteristic curve 6) for the entire filter system function and frequency response, and draw its amplitude-frequency characteristic curve.)