LTE-WiFi Carrier Aggregation for Future 5G Systems: A Feasibility Study and Research Challenges

Multi-Radio Access Technology (multi-RATs) carrier aggregation (CA), also known as multi-Flow CA, is an envisioned future technique that allows channels from different RATs to be aggregated and allocated to the end user. This technique allows for an efficient utilization of the fragmented and crowded spectrum, as well as for coordination and load balancing between the different RATs. The concept of CA was introduced in 3GPP's Release 10 for the Long Term Evolution (LTE) systems, and the feasibility of LTE-LTE CA scenarios has been studied. In this work, we conducted a preliminary study of the feasibility of LTE-WiFi CA. We assume a CA mode where the LTE system borrows from the WiFi spectrum. Our study shows that this CA mode is compatible with the LTE-Advanced physical layer specifications, and is therefore theoretically achievable. For practical deployments, we show that the current advances in cellular technologies form good grounds for actual deployment of integrated LTE-WiFi systems. We also highlight the main research challenges and suggestions for future work. (C) 2014 Elsevier B.V.