## 2 Fundamentals of Terahertz Communication
### The Terahertz Spectrum
#### 2.1.3 Higher Data Rates  
The number of THz frequencies that are available is not restricted as in the other bands, which lends this frequency range to use for high-speed transmissions with a rate control of more than 1 Tbps, as this rate is feasible in specified settings [21; 35; 36]. In comparison, the typical rates for optical-based communication system range from 100 Gbps to 400 Gbps in commercial applications [37; 38]. These promising features indicate that the THz spectrum can offer 10\(\times\) higher data rates, making it applicable for such applications as 8K streaming  
Figure 4: THz communication advancement spectrum. \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Studies** & **Technology** & **Frequency Range** & **Wavelength Range** & **Component Size** \\ \hline \hline
[31] & Microwave & 300 MHz–30 GHz & 1 mm–1 m & Bulky antennas \\ \hline
[32] & Millimeter-Wave & 30 GHz–300 GHz & 1 mm–10 mm & Compact antennas \\ \hline
[33] & Terahertz (THz) & 300 GHz–10 THz & 30 μm–1 mm & Ultra-compact devices \\ \hline
[21] & Technology & Frequency Range & Wavelength Range & Component Size \\ \hline
[34] & Microwave & 300 MHz–30 GHz & 1 mm–1 m & Bulky antennas \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparative analysis of shorter wavelengths across technologies. video streams, which need 100 Mbps per stream, or inter-satellite links that will need 10-50 Gbps per channel [39; 40]. Techniques in nanofabrication have also enhanced the spectral efficiency of THz systems by attaining 4 bits/Hz efficiencies in dense network conditions [22; 41]. These advancements guarantee the readiness of THz technologies to cater to the increasing need for high-speed, low-delay communication in schools, urban centers, and all other places. The achievable data rate in a communication system is governed by the Shannon-Hartley theorem:  
\[\mathrm{R}=\mathrm{B}\cdot\mathrm{log}_{2}\bigg{(}1+\frac{\mathrm{P}}{\mathrm{ N}_{0}\mathrm{B}}\bigg{)} \tag{5}\]  
where R is the data rate in bits per second, P is the signal power in watts, N\({}_{0}\) is the noise power spectral density, and B is the bandwidth. For THz systems with B = 1 THz and high signal-to-noise ratios, R easily exceeds 1 Tbps. In pulse-based THz communication, the data rate can also be approximated by the inverse of the pulse duration (\(\tau_{\mathrm{P}}\)):  
\[\mathrm{R}_{\mathrm{P}}=\frac{1}{\tau_{\mathrm{P}}} \tag{6}\]  
Concerning ultra-short pulses with durations of 1 Gbps, the data rates can go up to 1 Tbps, which elicits confidence in the use of THz frequencies. Table 4 highlights the data rates supported by THz (terahertz) communication technology. These data rates are essential for applications that depend on a high throughput, such as 6G networks, which require ultra-fast data transmission, and real-time analytics, which rely on the rapid processing of large datasets. Although the THz spectrum offers immense potential for a wide range of applications, it is not without its challenges. These difficulties must be addressed to fully harness its capabilities. The atmospheric attenuation, especially by water vapor, ranges between 0 and 20 dB per kilometer, particularly at specific bands, significantly reducing the range of this technology in especially wet environments [42]. These losses can only be overcome by using better materials like graphene base modulators, which have experimentally reduced the attenuation by about 40%. The economic viability of this technology remains a significant challenge, limiting its widespread adoption. Known THz sources, like quantum cascade lasers, are relatively expensive and cost from USD 10,000 to USD 50,000 per piece. Making THz technologies adaptable for commercial networks will also require the creation of cost-efficient manufacturing processes [43]. In conclusion, it can be stated that the THz spectrum is a frontier area with high potential for a major impact on the development of novel communication systems [44].