# Performance Modeling and Analysis of LTE/Wi-Fi Coexistence
## 4 Simulation Results and Discussion
Below the offered bit rate of 16.7 Mbit/s, the AABR results are accomplished for all services; however, the VOLTE with the highest priority still has better results among the other services. Because most of the requests are served by the inner zone, above a 16.7 Mbit/s offered bit rate, all service performances reach a stable state. As the traffic increases, the performance reaches zero Mbit/s. In Figure 6, not only is the performance of LTE and Wi-Fi with coexistence shown, but the overall cell performance is also demonstrated to explain the effect of coexistence on cell performance as well. LTE performance is degraded compared to Wi-Fi performance at different offered bit rates. Nevertheless, the main idea of the proposed integration and interoperability of both technologies is to provide better performance for the whole cell and the whole network, by distributing the load between both technologies so that the capacity of the network is maximized. Because of this achievement, it can be noticed from Figure 6 for the blocking probability results that the performance of the whole cell is maximized at different offered bit rates. Therefore, the main objective of the proposed model is achieved. In Figure 7, the packet delay budget is given in milliseconds (ms). Agreeing with Table 3, one can notice that analogous delay budgets are attained for LTE and Wi-Fi, and, at higher total offered bit rates, it reaches the value of zero ms. Moreover, in the same figure, while both technologies coexist, the cell overall delay budget is also attained. For example, at the lower offered bit rate, the delay budget in the whole cell is around 340 ms; it reaches around 120 ms at the higher offered bit rate. On the other hand, an excellent performance or the delay budget is attained when both technologies coexist. It reaches around 160 ms for a low value of the offered bit rate and 0 ms at the maximum offered bit rate. It should be noticed here that, with this integration between both technologies, the best effort requests are served by the Wi-Fi zone, while requests that are more sensitive are left to be served by the LTE zone. Thinking about real-life examples, assume you are walking in the mall while you are using your smartphone. Now, your smartphone automatically switches to the strongest signal, which is most probably the signal of Wi-Fi. However, when you need to access some sensitive information, then your smartphone switches to the signal of mobile data, which is LTE or 4G. This is why the throughput results of the Wi-Fi zone outperform the LTE zone at diverse offered bit rates, as shown in Figure 8. A similar manner can be observed for the utilization results shown in Figure 9. Since only high quality and sensitive data requests are served by the LTE zone, the Wi-Fi zone, which is responsible for most of the requests, outperforms LTE performance concerning utilization measures. The comparative results with and without coexistence are demonstrated as the second group of results (Figures 10-12). These results are to compare the performance of both technologies with and without coexistence. Additionally, the figures show that LTE performance degrades while coexisting with Wi-Fi. Looking at Figure 10, one can notice that the LTE average bit rate is improved while functioning on its own. When coexisting with Wi-Fi, the performance dramatically degrades. On the other hand, some other figures prove the opposite. Figure 11 demonstrates the blocking probability, where better results are attained for LTE while coexisting with Wi-Fi. Moreover, wonderful results are shown in Figure 12, where a better delay budget can be achieved for LTE while coexisting with Wi-Fi. This status can be explained as follows: through coexistence, the traffic is divided between LTE and Wi-Fi; however, LTE still needs to serve some high-quality and sensitive requests while functioning on its own. Figure 11: Blocking probability comparison. Figure 12: Delay comparison. Figure 4:0 Average bit-rate comparison.