# Performance Modeling and Analysis of LTE/Wi-Fi Coexistence
## 2 Related Work  
In wireless communication technology, Wi-Fi stands for \"wireless fidelity\"; it is the name of a wireless technology protocol that allows us to communicate data wirelessly. LTE stands for \"long-term evolution\", which is the fourth generation wireless broadband technology standard. LTE is a very reliable technology with high speed and top security for smart devices and smart phones. Although Wi-Fi is the preferred technology of different enterprises, the LTE/Wi-Fi debate took place between different enterprises, concerning which form of technology should be used. Following the technological developments and because of the need for Internet connection that is reliable with excellent performance, maximum capacity and Internet of Things (IoT) applications, many enterprises recognized the need for cellular networks, such as LTE. Both LTE and Wi-Fi provide data access over the Internet and both use the wireless spectrum, however, they are varied in terms of performance, speed, security, coverage, and capacity. Nevertheless, in our daily life activities, we rely on both technologies in communication, news, entertainment, health, education, and other activities. Evidently, when LTE is presented to share an unlicensed spectrum with other technologies, such as Wi-Fi, some issues appear since LTE needs to have full control of the spectrum during its data transmission [7]. Therefore, the interoperability model that provides us with the integration between both technologies has a significant advantage on the wireless technology, as LTE technology with a licensed spectrum incorporates Wi-Fi technology that provides an unlicensed spectrum. 3 GPP considered and adopted LTE and LTE-Advanced as leading cellular mobile communication services, and they are intensively studying the different coexistence scenarios with other technologies [8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21]. The research [8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21] focused on improving the network performance, while both technologies coexisted, rather than the individual performance of each technology. Some other research [22; 23] focused on the effect of the coexistence principle on both technologies. Our research combines both objectives, as we are interested in studying the effect of coexistence on each technology, however, our primary focus is to balance the traffic load among both technologies so that the overall network performance and capacity are maximized. Regarding the first group of research, in [8], the coexistence of Wi-Fi and LTE is studied based on a human-centric approach, for which human satisfaction is the major concern in this research work. User satisfaction is not preserved by the coexistence of both technologies, however, by performance modeling and simulation under semi-adaptive partitioning, this level of satisfaction is facilitated and, therefore, the authors conclude that there is no advantage to the coexistence between Wi-Fi and LTE when the unlicensed spectrum is partitioned. This means there is a possibility of deploying Wi-Fi without LTE in the unlicensed spectrum. Forming a coexistence gap in the time and space domain was the idea in [9], where the authors provide a flexible collaboration among LTE and Wi-Fi networks. The integration between both technologies is presented in the demonstrated simulation results. It dramatically improved network throughput and channel delay, taking into consideration that the achieved improvement in performance depends on some network configurations, such as the assumed distance between LTE and Wi-Fi networks. In [10], the authors proposed a new model of fair coexistence for LTE and Wi-Fi, so that the Carrier Sensing Adaptive Transmission mechanism can be optimized. Additionally, the authors presented a throughput Optimal Channel Selection algorithm for LTE and, according to the demonstrated numerical results, it is shown that the system throughput is dramatically improved.