# mIoT Slice for 5G Systems: Design and Performance Evaluation
## 5 Performance Evaluations
### Simulation Results and Discussion  
In Figure 4, we focus our attention on the variation of the total CP signaling during the simulation interval of interest and on its components related to bearer establishment, re-setup and update. For the sake of simplicity, in this analysis, we consider a single access node. We also assume a density of \(10^{3}\)  UE/km\({}^{2}\) and that all UEs have an AP = 30 min. Observing the time evolution of the CP signaling on the left-hand side in 4G, we can note that bearers are established during the first half interval of the simulation. In 4G, this requires one bearer establishment for each PhD. In the 5 GS mIoT slice, bearer establishments are needed only for VDs which is a much lower number compared to PhDs (this depends on the ratio between the number of PhDs and U (Maximum number of PhDs for a VD)) while the remainder of CP signaling is related to bearer updates (which involved less load for the CP). Once bearers are established, the CP traffic is related to re-setup when PhDs transmit other traffic. In 4G, the load of re-setup is the same as in the establishment phase (i.e., one re-setup for each PhD) and this means that the load towards the CN in 4G does not significantly change during establishment and re-setup phases. Although re-setup might involve less load, the number of CP messages is the same as for the establishment, i.e., the re-setup in 4G involves the same CP msg/s as for the establishment phase. With 5 GS mIoT slice, only one re-setup for each VD is needed, i.e., the re-setup of one aggregate core network bearer does not require bearer updates as the bearer has been already established. This means that after the establishment phase, the CP signaling is very limited in the 5 GS mIoT slice. Another aspect to underline is that the load due to re-setup can be tuned with a different strategy when creating the VDs. In our analysis, VDs are created based on the traffic pattern, i.e., two consecutive transmitting PhDs are associated to the same VD if the VD has still enough space (i.e., U is not exceeded). This means that all PhDs gathered in a VD transmit their UP traffic close to each other, thus the aggregate core network bearer associated to the VD is detached due to UP inactivity and then re-setup. The PhD-VD association could be enhanced by considering application (e.g., traffic patterns) and UE (e.g., density) contexts to avoid the expiration of an aggregate core network bearer thus further reducing the CP signaling. Possible strategies could be to associate consecutive transmitting PhDs to different VDs or to add a new PhD to an existing VD only when the lifetime related to the VD is close to expire. After the analysis of the time variation of the CP signaling generated by a single access node, the evaluation will now consider a closer to reality scenario with 104 RAN nodes connected to the same CN. To understand the behavior of the two approaches discussed in this paper, in this analysis, the UE density is varied (the AP is 30 min) and, for the 5 GS mIoT, U and T parameters have been varied to analyze their impact on the achieved performance. Parameters used for this analysis are summarized in Table 1. In Figure 6, we analyze the CP signaling related to bearer management, and study the compositions of the different components. In this analysis, establishments and re-setups are gathered together for the sake of simplicity, but given the fact that AP = 30 min and the interval of interest is 1 h, establishments and re-setup are equally split: UEs transmit on average two packets in the simulation period of 1 h, where the first transmission requires a bearer establishment, while the second transmission only asks for bearer re-setup. The 5 GS mIoT introduces a reduction of \(\sim\)50% for the CP bearer signaling compared to 4G for this traffic pattern.