# Comparative Analysis of 5G Mobile Communication Network Architectures
## 4 Simulation Model  
### Simulation Model Overview  
To assess the capabilities of the different architectures, a simulation model of the network architecture was constructed. Figure 4 shows the communication network modeled on the left, and the overall structure of the corresponding simulation model on the right.  
The communication network shown on the left in the figure has a multi-tiered structure. The central cloud is located in Tier-2, while six edge clouds are located in Tier-1. The central cloud is connected to the edge cloud in a star topology structure. The various UEs communicate continuously with the edge clouds. The edge clouds and the central cloud are connected through an IP network based on optical transmission technology. The network simulation model was constructed so that it represented the CCC, HCC, or MEC architectures depending on the computing resource allocation between the central cloud and edge clouds. Thus allocating 100% of the computing resources to the central cloud represented the CCC architecture, while allocating 100% of computing resources to the edge clouds represented the MEC architecture. The HCC architecture was represented by any architecture in which the computing resources were allocated to both the central and edge clouds.  
The simulation model was developed in the Microsoft Windows 10 (64 bit) environment on a laptop computer equipped with Intel Core i5-6200U processor with 8 GB of RAM. The main module used to develop simulation model was Python-based SimPy (version 3.0.10), which is a discrete-event simulation framework. The additional modules used were NumPy for data analysis and Matplotlib for graphic output.  
As shown on the right side of Figure 4, the simulation model is divided into interface, simulation, and analysis modules. The interface module permits the user to input simulation parameter values, collect simulation results, and produce status information. The simulation module receives information from the interface module and simulates the communication network response.  
Figure 4: Network architecture simulation model.  
The simulation module can be decomposed into a cloud module and a link module. The cloud module can be realized as an edge cloud or a central cloud, where the central cloud can be placed in a higher tier. Moreover, for each individual cloud, an arbitrary amount of computing resources can be allocated, and the offloading decision-making framework and policy to execute it can be inputted. The link module is used to realize network links between clouds, and by adjusting the physical parameters, such as the latency characteristics and variance, it can simulate wired and wireless links.  
The analysis module receives the simulation results from the interface module and visualizes it appropriately to suit the objective of the analysis. By displaying the results in different types of graphs, it allows efficient analysis and interpretation of the simulation results.  
There are two newly designed modules incorporated into the network architecture simulation model to specifically simulate and optimize the HCC architecture. The first module is the HCC offloading decision module, and the second one is the HCC computing resource allocation module.