# From Cyber-Physical Convergence to Digital Twins: A Review on Edge Computing Use Case Designs
## 7 Edge Computing Digital Twins--Special Use Cases  
With the 5G NR already commissioned in most parts of the world and still being commissioned in others, the era of network softwarization is already at its height. The 6G networks, which are affectionately referred to as the era of network intelligitization, are quickly making their way into the wireless communication space [109]. Through the digital transformation, the current 5G networks are quickly transforming themselves towards 6G through the transformation of their access and resource provisioning strategies. Edge computing, which is a strategy for provisioning computational resources at the edge of the network in order to advance the requirements of latency-critical services, enables MNOs to keep core NFs at the edge of the network. As a result, computational software in the form of NFs is kept in tens of thousands of remote locations all running consistently and with uniform security standards. With these NFs or network applications running close to the end users, network latency is reduced, which also allows service providers to offer new services that are not possible with cloud computing [110]. Most of the use cases and applications that require lower latencies, such as vehicular communications, can benefit from the faster, more reliable services compared to cloud computing [111]. Other benefits of edge computing include low latency, privacy protection, context awareness, and reduced bandwidth consumption. In a nutshell, the structure of the cloud-fog-edge continuum is as follows:  
* The Cloud Layer: The cloud layer, which is also known as the core (regional data center) of the MNO. This layer is traditionally a non-edge tier, and it is most often owned and operated by the public cloud provider, a CSP, or even a larger enterprise [112]. It is responsible for processing big data, business logic, and data warehousing. Cloud computing is the most prevalent tool for user data management in this layer.
* The Fog Layer: The fog computing layer is a computing layer lying between the edge and the cloud. Since it is commonly owned and operated by a CSP, it is known as the  
\begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Objective** & **Technique** & **Algorithm** & **Considerations** & **Reference(s)** \\ \hline Describe & Identify & Reinforcement & Aligning with & [106] \\ a network DT & different & learning & open RAN & \\ architecture & application & & for implementation & \\ focusing on & use cases & & used for training & \\ the RAN and & and train & & RL-based capacity- & \\ also align with & algorithms & & sharing solutions & \\ open RAN & under & & for network slicing & \\  & different & & & \\ conditions & & & & \\ \hline Design a DT & Combine & Reinforcement & Future network & [108] \\ technique for & expert & learning & states must be & \\ self-optimizing & knowledge & & predicted based on & \\ mobile & with RL & & which optimization & \\ networks & and DT & & decisions are & \\  & & & generated by & \\  & & & expert knowledge & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Application of the digital twin technology in 6G networks.  
service provider edge. In other words, it is a tier located between the core (regional data centers) and the last mile, i.e., the access network where the network operator serves multiple customers [113]. The fog layer is also responsible for local network access, data analysis and data reduction, control response, as well as function virtualization.
* The Edge Layer: Also known as the end user premises edge, the edge layer is responsible for the real-time processing of large volumes of data. Edge computing, which refers to data computation that takes place at the edge of the network, is the most prevalent tool for user data management at this layer. Along with fog computing, edge computing has been used widely in increasing the speed and the efficiency of data processing, as well as bringing intelligence closer to the user devices.