## 4 Deployment of Cloud-Native Core Network in ComEdge
### Example Analysis  
To further elucidate the actual processes of core network deployment costs and internode control signaling overhead in multiple edge nodes, it is necessary to provide a comprehensive analysis with illustrative examples of the key control plane processes that affect the placement cost of cloud-native edge core networks, such as user registration and session establishment. Furthermore, to gain a more intuitive understanding of the distributed core network deployment approaches, it is necessary to provide examples and compare different static edge core network deployment schemes. Based on the initial registration and session establishment, these two fundamental processes clearly demonstrate the control signaling interactions among various network functions in the core network when fulfilling user service requests. Figure 4 illustrates the procedures for the initial registration and session establishment in the context of 5G network deployment. During the UE's initial registration, the Authentication and Mobility Management Function (AMF) authenticates the UE and communicates QoS/billing profiles to the Session Management Function (SMF). Following this, the SMF selects a User Plane Function (UPF) to serve as the anchor gateway for session establishment. To initiate uplink data transmission, the UE first establishes a radio connection with the base station, which subsequently sends a service request to the AMF. The AMF, in turn, replicates session states to the base station for effective QoS enforcement. For the delivery of downlink traffic, it is imperative for the anchor gateway to notify the AMF of data arrival. Subsequently, the AMF notifies the base station to initiate paging for the UE. If this paging process succeeds, the UE repeats the aforementioned procedure to establish the session anew. Based on the above process, it is possible to quantitatively determine the control signaling overhead between CNFs. With the rise of edge computing and related infrastructure development, deploying the core network at the edge has become a major trend. The edge core network is positioned closer to users, which leads to a reduction in data transmission delay and the upload of sensitive data. This proximity helps conserve network bandwidth, enhance data transmission efficiency, and alleviate network congestion while simultaneously safeguarding privacy and data security. In additon, utilizing edge nodes as backup nodes reduces the risk of single point failure and enhances system reliability. Lastly, in comparison to large data centers, the edge core network significantly minimizes energy consumption and operational costs. Then, a brief description is provided for three different examples of edge core network deployment. In Figure 5a, a relatively complete core network is deployed only on Edge Node 2. The direct consequence of this is that users outside Area 2 need to incur higher edge control overhead for initial registration and session establishment processes. Additionally, the resource utilization of the entire edge system is severely imbalanced. This is a scenario that we should try to avoid in practical deployments. In Figure 5b, a relatively complete core network is distributedly deployed on Edge Nodes 1, 2, and 3. In this case, the resource utilization of the edge system is more balanced, and it also improves, to some extent, the back-haul control overhead for users in Areas 1, 2, and 3. However, this deployment approach still has drawbacks when the number of users increases, especially when there is a significant increase in users in Areas 3 and 4. This can lead to more frequent interactions between AMF, SMF, UPF, and thus consume a substantial amount of inter-node communication resources. Compared to the first two scenarios, the third deployment scenario is more reasonable.