## 5 Overview of 5G-Enabling Technologies
### Key 5G-Enabling Technologies
#### 5.1.1 The 5G Millimeter Wave (mmWave)  
The microwave bands cannot provide the increased spectrum capacity required by 5G applications because they are currently occupied by early wireless technologies such as 2G, 3G, and 4G, with some bandwidth reserved for other uses. Latest technologies such as 5G are designed to operate on the new millimeter wave spectrum bands, which have a  
Figure 4: An Overview of Critical 5G Technology Enablers. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Requirement** & **Definition** & **5G Specifications** & **Enabling Technology** \\ \hline Peak data rate & In ideal situations, the maximum data rate per user/device (in Gbit/s) & 10–20 Gbit/s (peak data rate), 100 Mbps cell edge & Millimeter wave, massive MIMO, dense network, cognitive radio network \\ \hline User experienced data rate & The maximum data rate that a mobile device can achieve (in Mbit/s) across its coverage area. & 1 ms & D2D Communication, MEC \\ \hline Latency & The amount of time taken for data to travel across a network (in ms). & 500 km/h (e.g., for high-speed trains) & Advanced heterogeneous networks \\ \hline Mobility & Maximum speed (in km/h) at which certain QoS and continuous transfer between radio nodes can be achieved. & 106 devices/km\({}^{2}\) & Internet-of-things, M2M, D2D \\ \hline Connection density & The total number of connected and/or accessible devices per unit area (per km\({}^{2}\)). & 100\(\times\) greater than IMT-Advanced & M-MIMO, mmWave \\ \hline Energy efficiency & The number of bits transmitted for every unit of energy consumed & 3\(\times\) greater than IMT-Advanced & M-MIMO \\ \hline Spectral efficiency & Average data throughput per unit of spectrum resource and per cell (bit/s/Hz). & 10 Mbit/s/m\({}^{2}\) & mmWave, D2D, NFV \\ \hline Area traffic capacity & Total traffic volume per geographical area served (in Mbit/s/m\({}^{2}\)). & 10 Mbit/s/m\({}^{2}\) & mmWave, D2D, NFV \\ \hline \hline \end{tabular}
\end{table} 
Table 8: 5G requirements and the associated enabling technologies. larger spectrum than microwave bands and operate at frequencies ranging from 24 GHz to 100 GHz [22]. Researchers have conducted several works to evaluate the advantages and challenges of deploying a 5G system at the millimeter wave. [PERSON] et al. [69] investigated whether the mmWave frequency band was suitable for 5G new radio and provided a resource allocation technique for concurrent D2D communication in the mmWave band that maintains network connection and enhances network efficiency. Their findings can be used to simulate D2D communications in the mmWave frequencies in 5G cellular systems. This is due to the fact that huge mmWave BS can be set to achieve a high transmission rate as well as overall efficiency. In the work of [PERSON] et al. [70], a brief overview of the crowded 1-3 GHz band of the cellular spectrum was presented. The channel parameters relating mmWave signal attenuation due to free space propagation, rain, and atmospheric gases were also discussed, along with other important elements to build up mmWave communications in 5G. The mmWave hybrid beamforming architecture technique was also examined. The authors of the work offered solutions to the blocking effect brought on by penetration damage in mmWave communications. The requirements and design challenges of mmWave 5G antennas for mobile devices were discussed by [PERSON] et al. [71]. The researchers used 3D planer mesh-grid antenna elements to produce a small, low-profile 60 GHz array of antenna modules. A framework was developed to accommodate the concept of employing antenna components to power cellular telephones on mmWave-based 5G smartphones. They also double-checked the mesh-grid array of antennas with the polarized beam to avoid potential hardware issues. In a related report, [PERSON] et al. [72] examined the usage of unused millimeter wave frequency spectrum for 5G wireless connectivity.