Communications of the ACM
SkyCore: Moving Core to the Edge for Untethered and Reliable UAV-Based LTE Networks
The advances in unmanned aerial vehicle (UAV) technology have empowered mobile operators to deploy LTE (long-term evolution) base stations (BSs) on UAVs and provide on-demand, adaptive connectivity to hotspot venues as well as emergency scenarios. However, today's evolved packet core (EPC) that orchestrates LTE's radio access network (RAN) faces fundamental limitations in catering to such a challenging, wireless, and mobile UAV environment, particularly in the presence of multiple BSs (UAVs). In this work, we argue for and propose an alternate, radical edge EPC design, called SkyCore that pushes the EPC functionality to the extreme edge of the core network—collapses the EPC into a single, lightweight, self-contained entity that is colocated with each of the UAV BS. SkyCore incorporates elements that are designed to address the unique challenges facing such a distributed design in the UAV environment, namely the resource constraints of UAV platforms, and the distributed management of pronounced UAV and UE mobility. We build and deploy a fully functional version of SkyCore on a two-UAV LTE network and showcase its (i) ability to interoperate with commercial LTE BSs as well as smartphones, (ii) support for both hotspot and stand-alone multi-UAV deployments, and (iii) superior control and data plane performance compared to other EPC variants in this environment.
1. Introduction
Mobile LTE (long-term evolution) networks that are ubiquitous today are deployed after sufficient RF planning in a region. However, the static nature of LTE base station (BS) deployments limits their ability to cater to certain key 5G use cases—surging traffic demands in hotspots (e.g., stadiums and event centers), as well as their availability in emergency situations (e.g., natural disasters), where the infrastructure could itself be compromised. Providing an additional degree of freedom for base stations, namely mobility, allows them to break away from such limitations.
UAV driven mobile networks. Advances in unmanned aerial vehicle (UAV) technology have empowered operators to take on-demand, outdoor connectivity to another level, by allowing their base stations to be deployed aerially on UAVs (Figure 1), thereby offering complete flexibility in their deployment and optimization. Mobile operators such as AT&T and Verizon have both conducted trials with LTE base stations mounted on UAVs9,8 (helicopter and fixed-wing aircraft, respectively). AT&T also provided LTE network services from its UAV in the aftermath of hurricane Maria in Puerto Rico last year.3 Further, with the availability of shared access spectrum such as CBRS2 in 3.5 GHz, this also opens the door for smaller, greenfield operators to deploy and provide on-demand, private LTE connectivity services without the heavy cost associated with spectrum and deployment.
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