## 4 Simulation Results and Discussions
### Simulation Setup  
In this section, we discuss the simulation model of the proposed ASA system for network slices in 5G C-RAN. To validate the results of the proposed system, a discrete event simulation program was developed using MATLAB. The intended simulation model is composed of a single cell set up with one RRH based on the 3 GPP 5G system model. The total bandwidth considered is B = 20 MHz, subdivided into 100 RBs of 12 subcarriers. Three different 5G slices (URLLC, eMBB, and mMTC) with multiple priority levels share the BBU pool bandwidth of the 5G C-RAN, and each slice traffic has different parameters considering its required QoS. We discuss different performance metrics from the schemes in [14; 15] and 5G Releases and recommendations.  
The simulation has three FIFO queues that hold the value of the arrival time and drop time of each connection request. Table 9 shows the main simulation parameters.  
The QoS requirements for the 5G network slices utilized in our simulation are shown in Table 10. The parameters in Tables 9 and 10 are used unless otherwise specified. For the URLLC slice, we set its priority ratio, \(P_{URLLC}\), to 50%, meaning it has the highest priority level. We set the queuing delay for the URLLC to 1 ms, and the data rate is 128 Kbps. Moreover, for the eMBB slice, we set its priority ratio, \(P_{eMBB}\), to 35%, meaning it has a medium priority level. In addition, we set the queuing delay for the eMBB to 4 ms, and the data rate is 256 Kbps. For the mMTC slice, we set its priority ratio, \(P_{mMTC}\), to 15%, meaning it has the lowest priority level. We set the queuing delay for the mMTC to 7 ms, and the data rate is 64 Kbps.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**5G Slice** & **Priority Ratio** & **Delay Budget** & **Rate Budget** \\ \hline URLLC & \(P_{URLLC}=50\%\) & 1 ms & 128 Kbps \\ \hline eMBB & \(P_{eMBB}=35\%\) & 4 ms & 256 Kbps \\ \hline mMTC & \(P_{mMTC}=15\%\) & 7 ms & 64 Kbps \\ \hline \hline \end{tabular}
\end{table}
Table 10: QoS requirements for 5G network slices.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Assumption** \\ \hline System bandwidth & 20 MHz (100 PRBs, 180 kHz per PRB) \\ \hline TTI & 1 ms \\ \hline Number of PRBs for data transmission & 96 \\ \hline Number of PRBs for control transmission & 4 \\ \hline User arrival & Poisson process \\ \hline Number of admitted calls simulated & 1,000,000 \\ \hline Call duration & Exponential 120 sec. \\ \hline Calls Queue size & 10 \\ \hline \hline \end{tabular}
\end{table}
Table 9: Simulation Parameters.  
Slices requests are generated in the system with a Poisson arrival process. The arrival rate of all slices' users is assumed to be the same (i.e., \(\lambda_{i}\) are equal for all i slices). In addition, the service rate of all slices' users is \(\mu\) where \(\mu_{i}=\mu\) for all i slices. The utilization rate is given by \(\lambda_{i}/\mu\). The simulation has four main events: initialize, arrival, depart, and drop events. The arrival and depart events are already described for each system in the previous section in Tables 6 and 8. The selection of the next event is based on the event's time. The simulation ends when the total number of served calls reaches one million.