Performance Assessment of QoS-Aware LTE Sessions Offloading Onto LAA/WiFi Systems

Fifth-generation (5G) cellular systems are expected to orchestrate a variety of air interfaces. In this heterogeneous setting 4G, LTE systems will remain of special importance providing service over a relatively large area not covered with the 3GPP new radio technology. However, the scarcity of radio resources below 6 GHz as well as constantly increasing user traffic demands call for efficient offloading strategy from the LTE network. In this paper, we consider and compare two LTE session offloading strategies, including LAA and WiFi offloading. Although by design, the LAA system supports quality-of-service (QoS) guarantees in terms of minimum throughput, the assured performance might still be violated by resource reallocations when satisfying the compulsory fairness criteria. To assess and compare the performance of these schemes, we develop an analytical framework that takes into account specifics of duty-cycle schedule-based Licensed Assisted LTE Access (LAA) system with connection admission control (CAC), resource reallocation mechanism, and realistic elastic traffic nature. As a special case of the developed framework, we also address the offloading of QoS-aware LTE sessions into conventional WiFi. Our numerical results indicate that WiFi offloading is characterized by a significantly greater number of offloaded sessions. However, this advantage comes at the expense of severe performance degradation in terms of minimum throughput guarantees. Implementing CAC procedures, LAA efficiently addresses this problem. We conclude that WiFi offloading of QoS-aware LTE sessions can be used in light traffic conditions only. On the other hand, offloading to the schedule-based LAA system allows preserving QoS over a wide range of arrival traffic statistics.