The Secret of the 5G Bandwagon: SDN Is the Engine

The excitement around 5G is understandable. Not simply a next-generation mobile service, 5G is emerging as an end-to-end system that will enable a fully mobile, connected society and support a wide range of use cases, including:

  • High-capacity, high-performance outdoor and indoor broadband access in dense urban areas, with mobile broadband everywhere;
  • Ultra-reliable and lifeline communication;
  • Extreme real-time communication to support delay-sensitive applications, including video, Internet of Things (IoT), machine-type communication, vehicle-to-X communications, e-health applications (such as remote surgery), hyperscale sensor networks, and industrial control and safety mechanisms, including control of electrical grids, traffic, self-driving cars, and "smart city" management; and
  • Entertainment, virtual reality and other new user experiences.

Just as high-speed Internet connectivity and smartphones have caused disruptive changes -- for example, in content production and consumption -- 5G will disrupt various industries, including telecom, automotive, healthcare, government, utilities, manufacturing and transportation.

5G will launch a new ecosystem of providers and open up opportunities to create completely new business models. It will also change the way carrier networks are designed. Technologies such as compute virtualization, SDN and NFV are fundamental to 5G. Indeed, without SDN the promise of 5G would remain unfulfilled.

A variety of organizations, not just carriers, need to educate themselves about this emerging technology and, if possible, contribute to its development through organizations such as the Open Networking Foundation (ONF) and Next Generation Mobile Networks (NGMN) alliance. Otherwise, they risk being left behind.

Implications of 5G's aggressive performance goals
To accommodate its many use cases, 5G must meet stringent performance requirements with regard to throughput, latency, reliability, resiliency, power efficiency and scalability. For example:

Speed and density: NGMN is looking for 50Mbit/s user throughput, with a goal of providing urban cores with downlink speeds of 300 Mbit/s and uplinks of 50 Mbit/s. Another goal is to support densities of 100 users/square kilometer in rural areas and 400 in suburban areas, with 10 and 20 Gbit/s per square km capacity, respectively. To achieve these speeds and densities, 5G will integrate new and existing radio-access technologies along with massive antennas, expanded spectrum and improved basestation coordination.

Latency: The target latency for 5G is 10ms end-to-end, with 1ms for special use cases requiring low latency (such as control functions). Latency is affected by distance, so hitting these targets will require operators to host the applications or content that a user wants within 1,000km -- that is, 10ms -- of that user. Providers that host content closer to the download point will have a competitive advantage over those that don't. Increasingly, cache means cash.

To achieve this, 5G network architectures must be much more decentralized and intelligent than today's. Network and cloud operators will need technology that can predict what type of content the user wants, which means understanding more about big data, analytics and software than ever before.

Why SDN is key to 5G
5G isn't just about bandwidth or low latency. It's also about flexibility, agility, manageability and being able to create new services. 5G operators will want their infrastructure to provide services they had not even thought of when it was installed. SDN is the foundation for these capabilities. SDN also means the end of single-purpose infrastructures.

SDN's separation of the control and data planes, open switch model, and network resource abstractions are key. They give operators dynamic control over a variety of functions, including the packet data network connection, variable QoS, downlink buffering, online charging, packet transcoding, legal intercept and selective chaining. Some of the SDN abstractions needed for 5G are currently being explored in ONF's Mobile Networks working group.

Already, numerous SDN-based architectures have been proposed for 5G. For example, NGMN envisions an architecture that leverages the separation of hardware and software, as well as the programmability offered by SDN and NFV. This native SDN/NFV architecture will cover 5G aspects ranging from devices, mobile/fixed infrastructure, network functions, value-enabling capabilities and all the management functions to orchestrate the 5G system.

SDN's well-defined resource model is fundamental to supporting the heterogeneous use cases envisioned under 5G, each of which has specific bandwidth, latency, etc. demands. To support new services and applications concurrently, operators can use SDN to easily program network resources into virtually isolated, end-to-end "slices" (or partitions) of the 5G network. These slices will encompass radio, backhaul, core and management domains, not simply switch resources.

An SDN-based architecture will enable operators to offer networks as-a-service and manage resources efficiently while running services continuously. Within the central office/data center, SDN will also help operators control resources for highly scalable packet processing and forwarding in the fast path (in the order of end-user session time). Providing flexibility and optimization in an operator's network, SDN will lower capex and opex, freeing funds to create innovative new services needed to remain competitive in a 5G world.

Be disruptive, not disrupted
5G will have a transformative effect, disrupting value chains while enabling opportunities for numerous industries as well as telecom and cloud operators. Partnerships will be established on multiple layers, ranging from sharing the infrastructure to exposing specific network capabilities as an end-to-end service and integrating partners' services into the 5G system through software.

The infrastructure for 5G will be defined by traditional standards bodies. However, 5G services and added value will come from an operator's unique software capabilities that leverage the open source community and de facto standards based on software practices. Consequently, it's important for operators to collaborate with the open source community and participate in organizations such as ONF that are defining these software interfaces and services.

For example, ONF's Mobile Networks group is applying SDN- and OpenFlow-based technology to mobile networks and defining extensions to the OpenFlow protocol to support wireless and mobile use cases. ONF's definition and coding of important northbound interfaces frees application developers from the specifics of the network implementation; likewise, ONF's leadership in developing common information models makes it easy to comparison shop and procure best-of-breed technology.

Organizations that help shape 5G will be better positioned to take advantage of the opportunities and new business models this next-generation mobility system presents. We encourage everyone to join us in this effort to build the SDN engine that propels 5G.

— Dan Pitt, Executive Director, Open Networking Foundation

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