# 电气工程代写|通讯系统作业代写communication system代考|ECE561

## 电气工程代写|通讯系统作业代写communication system代考|State of Art of THz Technology

All over the world, several researchers are interested in $\mathrm{THz}$ waves since they are able to significantly improve the performance of several devices and also new applications will take place thanks to this technology; unfortunately the design and development of solutions using this technology are manifested always expensive [8].

This interest in $\mathrm{THz}$ technologies $[9,10]$ is due to the fact that $\mathrm{THz}$ waves lay between two relevant frequency bands in telecommunication world Fig.1: infrared ( $30 \mu \mathrm{m}$ or $10 \mathrm{THz}$ ) and microwaves ( $1 \mathrm{~mm}$ or $0.3 \mathrm{THz}$, approximately) from which they take two interesting characters; firstly, they adopt the ability to focus and access a certain submillimeter spatial resolution; secondly, they penetrate dielectric materials, adding to this that they exhibit strong aptitudes for penetrating imagery by emphasizing spectroscopic relevance.
$\mathrm{THz}$ technology has several interesting properties:

• The wavelength of $\mathrm{THz}$ technology allows waves to penetrate many materials while providing higher spatial resolution than microwaves.
• The penetration depth is relatively large for several non-conductive materials: plastics, ceramics, etc. The THz thickness measurement of multilayer materials is non-destructive.
• Substances subjected to THz radiation exhibit characteristic spectral signatures due to excitation modes of their molecular arrangement. THz spectroscopy also makes it possible to identify substances or their chemical characterization.
• The non-contact measurement character since the propagation of $\mathrm{THz}$ waves in the air is low attenuation.
• Their non-destructive and non-ionizing qualities [2].

## 电气工程代写|通讯系统作业代写communication system代考|Advantage of MIMO Versus SISO System

Unlike the single input single output SISO which is a single antenna for transmission and only one for reception, the MIMO system with several antennas used for transmission and reception achieves a higher throughput thanks to the transmission of data simultaneously on several antennas what is called spatial multiplexing the MIMO system brings other advantages such as the diversity of antennas because each antenna is used with a precise angle [14]. This diversity improves the data link by giving different points of view that an antenna can be affected by an antenna unlike other antennas thanks to the difference in polarization.

Space-time block coding (STBC) is a technique used by MIMO systems which consists of transmitting copies of the same data on all antennas; this technique in combination with spatial multiplexing guarantees the reliability of data transmission. This technique has been able to overcome the problem of interference and obstacles encountered in SISO systems this redundancy in MIMOs guarantees more correct decoding by combining all received copies of the signal.

Another technique that is available with MIMO is beamforming. This method involves emitting individual rays so each lobe will be dedicated to a specific base station.

# 通讯系统代考

## 电气工程代写|通讯系统作业代写communication system代考|State of Art of THz Technology

• 的波长吨H和技术允许波穿透许多材料，同时提供比微波更高的空间分辨率。
• 几种非导电材料的穿透深度比较大：塑料、陶瓷等。多层材料的太赫兹厚度测量是无损的。
• 受到太赫兹辐射的物质由于其分子排列的激发模式而表现出特征光谱特征。太赫兹光谱还可以识别物质或其化学特征。
• 自传播以来的非接触测量特性吨H和空气中的波衰减低。
• 它们的非破坏性和非电离特性 [2]。

## 电气工程代写|通讯系统作业代写communication system代考|Advantage of MIMO Versus SISO System

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