## 6 The 5G Spectrum Standardization
### The 5G Deployment Modes  
There are two ways to implement 5G. The first is the Standalone 5G deployment paradigm, offering services over an entire 5G network. The second mode, Non-Standalone, uses a combination of 5G and LTE architectures to deliver services [5].  
1. Non-Standalone (NSA): The Non-Standalone mode of 5G NR deployment relies on the 4G core network for control plane operations, such as session management, resource allocation, handover management, authentication, and policy management. This deployment option provides 5G services without an end-to-end 5G network instead of relying on 4G system components. Telecom companies frequently use this method for the rapid and cost-effective deployment of 5G networks. Deploying a 5G network in NSA mode can provide faster data speeds but cannot guarantee all of the 5G objectives. However, with the assistance of an existing 4G network, operators can implement 5G, promoting early adoption of the technology, which is why the 3 GPP released a preliminary set of NSA requirements before the full 5G standard was released. A cell in the NSA approach performs the control plane activities, while the user plane connection is provided jointly by both the LTE eNodeB and the 5G gNodeB [64,158]. NSA architecture will allow mobile operators to start 5G deployment since the 4G infrastructures can be retained for deployment and, thus, reduce network operation time. The cost of network deployment will also be reduced since operators can rely on existing 4G infrastructures. However, it is important to note that the NSA design is incapable of matching the exceptional performance of 5G networks in terms of speed, low latency, high data rate, and other factors.
2. Standalone (SA): The 5G NR Standalone mode differentiates between LTE and 5G networks by defining a separate core and radio access network for each network. This enables the true realization of 5G goals and end-to-end 5G connectivity. A simpler core network with lower operating costs is possible with 5G. The ability to arrange different types of UEs in separate network slices, each with a different QoS and set of rules, is a new feature in the 5G core network when compared with the 4G core network. Because UEs with lower resource requirements can be placed on a separate network slice, systems with the same capacity can handle more UEs more effectively than if a single policy was used for all UE types. This prevents the allocation of unnecessary resources. This is especially helpful in facilitating significant IoT installations. Since most IoT devices are sensors that do not need very low latency or high data rates, these UEs can be placed in a different network slice. Critical Internet of Things deployments can be placed in a different network slice with low latency [159]. The SA deployment method ensures operators can achieve the highest level of performance promised by 5G implementation. The revolutionary nature of 5G is a result of the fast data transfer rates and extremely low latency it offers, among many other enhancements. This mode was created to function on the 5G FR2 frequency since the entire SA architecture is made up of 5G infrastructures. This will ensure the 5G network aimed at extremely low latency and large data speeds is achieved. Huge infrastructure costs associated with the SA roll-out are a significant obstacle since telecommunication service providers would need to completely redesign their current LTE networks.