### 电子工程代写|计算机及网络安全代写Computer and Network Security代考|CS155

statistics-lab™ 为您的留学生涯保驾护航 在代写计算机及网络安全Computer and Network Security方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写计算机及网络安全Computer and Network Security方面经验极为丰富，各种代写计算机及网络安全Computer and Network Security相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

## 电子工程代写|计算机及网络安全代写Computer and Network Security代考|Multiplexing of Transmission Signals

Quite often during the transmission of data over a network medium, the volume of transmitted data may far exceed the capacity of the medium. Whenever this happens, it may be possible to make multiple signal carriers share a transmission medium. This is referred to as multiplexing. There are two ways in which multiplexing can be achieved: time-division multiplexing (TMD) and frequency- division multiplexing (FDM).

In FDM, all data channels are first converted to analog form. Since a number of signals can be carried on a carrier, each analog signal is then modulated by a separate and different carrier frequency, and this makes their recovery possible during the demultiplexing process. The frequencies are then bundled on the carrier. At the receiving end, the demultiplexer can select the desired carrier signal and use it to extract the data signal for that channel in such a way that the bandwidths do not overlap. FDM has the advantage of supporting full-duplex communication.

TDM, on the other hand, works by dividing the channel into time slots that are allocated to the data streams before they are transmitted. At both ends of the transmission, if the sender and receiver agree on the time-slot assignments, then the receiver can easily recover and reconstruct the original data streams. Thus, multiple digital signals can be carried on one carrier by interleaving portions of each signal in time.

## 电子工程代写|计算机及网络安全代写Computer and Network Security代考|Wired Transmission Media

Wired transmission media are used in fixed networks physically connecting every network element. There are different types of physical media, the most common of which are copper wires, twisted pairs, coaxial cables, and optical fibers.

Copper Wires have been traditionally used in communication because of their low resistance to electrical currents that allows signals to travel even further. However, copper wires suffer interference from electromagnetic energy in the environment, and thus they must always be insulated.

Twisted Pair is a pair of wires consisting of one insulated copper wire wrapped around the other, forming frequent and numerous twists. Together, the twisted, insulated copper wires act as a full-duplex communication link. The twisting of the wires reduces the sensitivity of the cable to electromagnetic interference and also reduces the radiation of radio frequency noises that may interfere with nearby cables and electronic components. The capacity of the transmitting medium can be increased by bundling more than one pair of the twisted wires together in a protective coating. Because twisted pairs were far less expensive, easy to install, and had a high quality of voice data, they were widely used in telephone networks. However, because they are poor in upward scalability in transmission rate, distance, and bandwidth in LANs, twisted pair technology has been abandoned in favor of other technologies. Figure $1.8$ shows a twisted pair.

Coaxial Cables are dual-conductor cables with a shared inner conductor in the core of the cable protected by an insulation layer and the outer conductor surrounding the insulation. These cables are called coaxial because they share the inner conductor. The inner core conductor is usually made of solid copper wire but, at times, can also be made up of stranded wire. The outer conductor, which is made of braided wires, but sometimes made of metallic foil or both, commonly forms a protective tube around the inner conductor. This outer conductor is also further protected by annther outer enating called the sheath. Figure $1.9$ shows a enaxial eable. Coaxial cables are commonly used in television transmissions. Unlike twisted pairs, coaxial cables can be used over long distances. There are two types of coaxial cables: thinnet, a light and flexible cabling medium that is inexpensive and easy to install, and the thicknet, which is thicker and harder to break and can carry more signals for a longer distance than thinnet.

## 广义线性模型代考

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## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。