# Multiservice Loss Models in Single or Multi-Cluster C-RAN Supporting Quasi-Random Traffic
## 3 Evaluation
According to Figure 3, we conclude that (a) simulation and analytical TC probabilities results are almost identical, (b) the offered traffic-load increase leads to an increase of TC probabilities, and (c) the f-SC-SC model cannot behave similar to the f-MC-SC model because of the fact that the former refers to a single service class model. Figure 3: TC probabilities due to lack of CRUs. In Figures 4-6, we present TC probabilities results for the 1 st, 2 nd, and 3 rd RRH, respectively. More precisely, in Figure 4, we show the simulation and analytical TC probabilities results of \(B_{\text{r,I,S}}^{\text{TC}}\) for the three service classes of the f-MC-SC model and the corresponding analytical TC probabilities results for the f-SC-SC model. In the case of the f-SC-SC model, the first point in the x-axis of Figure 4 expresses the value of \(\alpha_{1}=6\) erl, while the last point (i.e., point 31) expresses the value of \(\alpha_{1}=42\) erl. Similarly, in Figure 5, we show the simulation and analytical TC probabilities results of \(B_{\text{r,2,S}}^{\text{TC}}\) for the two service classes of the f-MC-SC model and the corresponding analytical TC probabilities results for the f-SC-SC model. In the case of the f-SC-SC model, the first point in Figure 5 expresses the value of \(\alpha_{2}=5\) erl, while the last point (i.e., point 31) expresses the value of \(\alpha_{2}=35\) erl. Finally, in Figure 6, the third RRH is considered and we present the simulation and analytical TC probabilities results of \(B_{\text{r,3,S}}^{\text{TC}}\) for the two service classes of the f-MC-SC model and the corresponding analytical TC probabilities results for the f-SC-SC model. In the case of the f-SC-SC model, the first point in the x-axis of Figure 6 expresses the value of \(\alpha_{3}=4\) erl while the last point (i.e., point 31) expresses the value of \(\alpha_{3}=28\) erl. Based on Figures 4-6, we observe that (a) simulation and analytical TC probabilities results are almost identical in the f-MC-SC model which is expected as the proposed model has a PFS, (b) the TC probabilities results obtained via the f-SC-SC model cannot capture the behaviour of the f-MC-SC model, and (c) the TC probabilities results (because of the RRUs unavailability) increase as the offered traffic load increases but after a point (which is not easy to know it in advance) they decrease. This behaviour is justified by observing that the TC probabilities results due to the unavailability of CRUs (see Figure 3), increase when the traffic load becomes higher and thus more RRUs remain intact in the corresponding RRHs. A similar behaviour (a decrease in congestion probabilities, after a certain point, when the offered traffic load increases) has been observed in the past when studying classical multi-rate loss models under the complete sharing policy and the bandwidth reservation policy, particularly when two service classes are considered and the required RUs of each service class have a high difference [58; 59]. Under these conditions, congestion probabilities oscillations may occur and therefore it remains an open issue to study if such type of oscillations may occur in a multiservice C-RAN environment. Figure 4: TC probabilities due to RRUs unavailability (1 st RRH). In Figures 7-9, we study again the 1 st, 2 nd, and 3 rd RRH, respectively, and present the total TC probabilities (computed via (5) as well as (14), (15)). Based on Figures 7-9, we conclude that (a) simulation and analytical results are again almost identical, (b) the increase of offered traffic-load increases the corresponding total TC probabilities, and (c) the f-SC-SC model cannot behave similar to the proposed model. Figure 5: TC probabilities as the result of RRUs unavailability (2 nd RRH). Figure 6: TC probabilities as the result of RRUs unavailability (3 rd RRH). Figure 8: Total TC probabilities (2 nd RRH—all service classes). Figure 7: Total TC probabilities (1 st RRH—all service classes).