# Congestion Analysis of Transport Layer in a Multicell 5G DL Communication System
## 4 Discussion
As shown in Figure 15, data volume steadily increases up to approximately 90% PRB utilization. As the number of UE devices increases, the amount of data that needs to be sent by the gNB increases, but since there are no available PRBs, more  
Figure 11: DL user throughput vs. number of users. Figure 5.0 DL delay vs. PRB utilization. Figure 5.1 PRB utilization vs. number of users. Figure 5.2 DL delay vs. number of users. Figure 5.3 DL data volume vs. PRB utilization. The relationship between the utilization of PRBs and the number of users working in the cell is illustrated in Figure 16, which depicts how cell throughput shifts over time. Cell throughput increases linearly until there are 100 UE devices in the cell, reaching a maximum of approximately 800 Mbps. The variation in cell edge user throughput that results from an increase in PRB utilization is illustrated in Figure 5.4 Cell edge user throughput drops with the increase in PRB utilization since there are more UE devices in the cell. This causes a decrease in overall cell throughput. It is possible to sustain an average throughput of 20 Mbps at the cell edge with PRB utilization of approximately 38%. Figures 18 and 19 show how the PRB utilization and number of users influence the throughput experienced at the edge of a cell, respectively. When there are around 42 UE devices at the cell edge, a throughput of 20 Mbps is achieved on average. The decrease in cell edge throughput has a substantial impact on the communication link when the number of users exceeds that threshold. Figures 20 and 21 illustrate how user throughput shifts when the percentage of PRBs being utilized and the total number of users in the cells rise, respectively. User throughput drops as the number of UE devices and the PRB utilization increase. The decrease follows a linear pattern, and it becomes more noticeable when the cell is loaded to between 60 and 100% of its capacity. Figure 5.5 DL cell throughput vs. PRB utilization. Figure 5.6 DL cell throughput vs. number of users. Figure 5.7 DL cell edge user throughput vs. number of users. Figure 5.8 DL user throughput vs. DL PRB utilization. In Figure 20, we can observe a maximum user throughput of 700 Mbps when there are 20 UE devices. This value drastically falls to half (i.e., 350 Mbps) when there are 80 UE devices. From 120 UE devices onward, the user throughput is at its lowest. Figures 22 and 23 illustrate how the downlink latency shifts when the percentage of PRBs being used and the number of UE devices increase. The delay steadily increases up to around 93% PRB utilization, at which point it is approximately 20 ms. After that, it begins to rise at a faster rate as the buffer reaches its 100% capacity, leading to an increasing number of packets that need to wait in the buffer before being broadcast. The load becomes close to 100% PRB utilization when there are 80 or more UE devices, which explains why delay begins to grow at that time. The average latency decreases to 10 ms once there are 70 UE devices or less. Figure 5.9 DL user throughput vs. number of users. Figure 4:0 DL delay vs. PRB utilization. Table 4 provides a comparison of the metrics and results obtained using the single-cell and multicell environments. The results obtained in both environments simulated are of great importance and provide insightful information on how the 5G network behaves when dealing with congestion. The simulations showed that DL data volume was stable up to 80-90% PRB usage and the maximum throughput was about 1.2 Gbps in a single-cell scenario and 800 Mbps