The existing mobile network architecture was designed to meet requirements for voice and conventional MBB services. However, this previous organization has proven to be insufficiently flexible to support diversified 5G services due to multiple 3GPP version upgrades, a large number of NEs, complex interfaces.
The driving force behind the network architecture transformation includes the following aspects:
- Complex networks incorporating multiple services, standards, and site types – 5G networks must be able to provide diversified services of different KPIs, support co-existent accesses of multiple standards (5G, LTE, and Wi-Fi), and coordinate different site types (macro, micro, and pico base stations). The design challenge to create a network architecture capable of supporting such flexibility whilst meeting differentiated access demands is a brave endeavor to satisfy.
- Coordination of multi-connectivity technologies – 5G is expected to co-exist with LTE and Wi-Fi for an extended period of time incorporating multi-connectivity technologies and the new 5G air interface. Multi-connectivity technologies must be coordinated based on traffic and mobility requirements of user equipment to provide sufficient transmission throughput and mobile continuity.
- On-demand deployment of service anchors – 5G network architecture will be designed based on access sites and three-layer DCs. According to different service requirements, fiber/optic cable availability and network resource allocations, RAN real time and non-real time resources can be deployed on the site or on the access cloud side. This further requires that the service gateway location may also be deployed on the access cloud or on the core network side.
- Flexible orchestration of network functions – Service requirements vary with different network functions. eMBB requires a large throughput for scheduling. uRLLC requires ultra-low latency and high reliability. Networks must flexibly orchestrate network capabilities considering service characteristics, which significantly simplify network functions and increase network efficiency.
- Shorter period of service deployment – Various services have expanded the mobile network ecosystem and increased network deployment complexity. Rapidly deploying new services requires an improved set of life-cycle management processes involving network design, service deployment, and O&M.
The Service-Driven 5G Architecture
The service-driven 5G network architecture aims to flexibly and efficiently meet diversified mobile service requirements. With software-defined networking (SDN) and Network Functions Virtualization (NFV) supporting the underlying physical infrastructure, 5G comprehensively cloudifies access, transport, and core networks.
Cloud adoption allows for better support for diversified 5G services, and enables the key technologies of E2E network slicing, on-demand deployment of service anchors, and component-based network functions.
CloudRAN consists of sites and mobile cloud engines. This facility coordinates multiple services, operating on different standards, in various site types for RAN real time resources that require a number of computing resources. Multi-connectivity is introduced to allow on-demand network deployment for RAN non-real time resources.
Networks implement policy control using dynamic policy, semi-static user, and static network data stored in the unified database on the core network side.
Component-based control planes and programmable user planes allow for network function orchestration to ensure that networks can select corresponding control-plane or user-plane functions according to different service requirements.
The transport network consists of SDN controllers and underlying forwarding nodes. SDN controllers generate a series of specific data forwarding paths based on network topology and service requirements.
The enabling plane abstracts and analyzes network capabilities to implement network optimization or open network capabilities in the form of API. The top layer of the network architecture implements E2E automatic slicing and network resource management.