Building Resiliency Into 5G Open-source and Disaggregated Architecture

Today in the Internet era, communication service providers face tremendous constraints on increasing capital expenditures and operating expenses compared to the much less income growth. Cloud Radio Access Network (C-RAN) architecture has emerged as a potential candidate for the future wireless network that highlights the notion of service cloud, service-oriented resource scheduling, and management, thereby facilitating the utilization of both Network Functions Virtualization and Software-Defined Networking (NFV-SDN) technologies. The transport network reliability of the disaggregated C-RAN components is paramount to ensure reliable data communication. Our first contribution focuses on providing transport network resiliency support for the C-RAN architecture using a programmable optical software-defined network testbed. The testbed supports C-RAN functionalities by offering fronthaul, midhaul, and backhaul transport capabilities with increased reliability. The C-RAN components are further disaggregated and run as either virtual machines (VMs) or containers in a virtualized environment. To ensure load-balancing and fault-tolerance of the C-RAN components, our Optical programmable testbed with SDN capabilities supports live migration of C-RAN functions among data centers. OS container-based virtualization enables faster application instantiation than the hypervisor-based VM because of its smaller footprint size. However, in the context of the mobile network protocol stack, the open- source container migration software has yet to be developed to the full extent. Our second and third contributions focus on the live migration of containerized core network and RAN central unit virtual functions. The live migration is made feasible through our proof-of- concept implementation of the open-source container migration software. In the C-RAN architecture, the Next Generation NodeB (gNB) functions are decoupled into three entities, namely Radio Unit (RU), Distributed Unit (DU), and Central Unit (CU). These entities will likely be virtualized and distributed in micro and macro data centers. The virtualized CUs (vCUs) are decoupled further into virtualized CU Control-Plane (vCU- CP) and virtualized CU User-Plane (vCU-UP) to optimize the location of the RAN functions for 5G vertical use case scenarios and performance requirements. The vCU-CP handles the signaling functionality, such as connection establishment and hand-over. All the 5G Core Network control plane modules have a single point of contact with vCU-CP. Therefore, a study on resiliency on vCU-CP is important to avoid the single point of failure, which comes under our fourth contribution. Our proof-of-concept guaranteed the fronthaul network reliability of the 5G transport network and during VNF live migration, it ensured end-user service continuity without permanent UE interruption. In addition, the temporary downtime experienced during the live-migration is significantly lowered by more than 50% when using our container migration prototype compared to traditional VM solutions.