Azure Private Multi-access Edge Compute (MEC) combines Azure management, edge computing capability, and networking functionality into a unified platform for modern edge computing. Azure Private 5G Core (now in public preview) builds on this platform to offer high-speed, low-latency connectivity, well suited for enterprises building private cellular networks in domains such as energy, manufacturing, and defense. Azure Private 5G Core is a standards-compliant 5G packet core that authenticates and authorizes 5G devices to connect to the network. It applies policies to network traffic, allowing devices to reach application services, hosted either locally or in upstream locations from the enterprise site, such as in an Azure region or on the public Internet.
Our customers and partners are building modern, “5G SA” or “5G standalone” networks, bringing the advantages of 5G to their enterprise networks, such as improved energy efficiency, superior coverage, higher speeds, and lower latency. With over 100 trials executed or in progress, enterprise 5G networks have a bright future.
However, not all customers are ready for 5G. Some enterprises have large investments in older 4G LTE devices, or, perhaps due to supply chain issues or local regulations, they are unable to source 5G devices and radio in the near term. These enterprises can take advantage of the features of Azure Private 5G Core, such as the ability to remotely provision and monitor sites, and the simple consumption-based pricing model without having to deploy a separate, legacy 4G system to serve devices for a limited time.
Today, Azure Private 5G Core supports both 4G LTE and 5G SA deployments, solving this problem for our customers.
Our approach to 4G is simple and customer-centric: customers can deploy Azure Private 5G Core to serve 4G devices and radio, or 5G. Azure Private 5G Core shields the customer from complexity, with the user experience and management interaction being the same. In the remainder of this blog post we provide more detail to explain how we accomplish this.
Under the hood – the 4G Interworking Function
In the 4G world, the element that connects devices and radio access network (RAN) to the rest of the network is known as an EPC (Evolved Packet Core). In the 5G world, the analogous function is known as a 5GCore. The modes of communication for 4G and 5G are very different, including the protocols used, and the content of the messages that flow between devices, RAN and cores.
Azure’s Private 5G Core approach to support 4G is to communicate like an EPC when talking to 4G devices and a 5G Core when talking to 5G devices. This means that no changes are required on the devices or RAN. Customers can preserve their existing investments in 4G equipment, or they can purchase 4G devices now while waiting for 5G devices to be available in market.
The software element inside the Azure Private 5G Core that enables this capability is called a 4G Inter-working Function (4G IWF) and is unique to Microsoft. At a detailed technical level, the Microsoft 4G IWF element:
Exposes 4G NAS functionality with built in MME and HSS elements
Adds interworking functions which present S11 and S1-U interfaces to existing 4G elements
Handles protocol interworking and enrichment between GTPv2C (4G-facing) and the JSON/HTTP2 Service Based Interfaces (5G-facing).
Microsoft IWF and UPF solution supporting both 4G and 5G RAN
Azure Private 5G Core remains a 5G SA packet core. All provisioning operations, network policy capability, management and monitoring remain the same whether the customer is building a 4G network or a 5G network. When the customer is ready to pivot to 5G, a simple reconfiguration and software refresh turns down the 4G IWF function and positions the service for 5G clients.