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Transport Matters

June 1, 2020
Radio Is NOT the Only Key Ingredient in 5G — The radio tends to get all the attention in 5G discussions, but the underpinning transport networks that support next-gen mobile […]

Radio Is NOT the Only Key Ingredient in 5G —

The radio tends to get all the attention in 5G discussions, but the underpinning transport networks that support next-gen mobile are a major focus for our customers and a major driver of our work with NEMs. This is being driven by:

Densification of networks. The high volume of small cells that will be required in urban and city environments will be 200%-300% more than what is needed today, demanding substantial fiber deployments.

Need to feed the bandwidth beast. Once 5G networks are fulfilling heavy demand, data consumption will be off the charts and networks need to be prepped for this. In places like Korea, there is already double to triple data consumption versus 4G.

Networks need an edge. As edge computing architectures are planned, the network is being disaggregated, with more components and functions hosted at varying edge locations. These edge sites must deliver reliability and high performance, and transport networks are a major part of assuring them.

Network Preparation

5G discussions typically focus on what’s happening in the air, but it’s the transport networks that will ultimately bear the heaviest burden of new 5G services. Network slicing, IoT, autonomous vehicles — take your pick. Each arrives with 5G performance requirements that typically need to be addressed by the same network architecture. All these ultra-fast speed, ultra-low latency, massive capacity, and high reliability, requirements demand a herculean effort to support.

Assuring the performance of 5G requires the complex transmission of video, data, and voice, from the core network to end devices. 5G services will not work as expected if the underlying transport network can’t provide connectivity that meets the requirements of each service.

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Given that 5G networks are highly distributed and denser than any previous generation, they will have to bear unprecedented loads. Operators and network equipment vendors are being challenged to meet the significant 5G performance demands on the transport network, which are more challenging because of 5G’s high performance requirements, dynamic services, and flexible architectures.

An added complexity is that not all transport standards have been finalized, and new, competing standards are being proposed. With global markets eyeing more near-term commercial deployments, the crunch is on.

Much must be done to prep transport networks for 5G. Network equipment manufacturers (NEMs) are fast-tracking product development, while operators evaluate 5G standards and the vendors best prepared to meet their next-gen architecture vision.

As a result, we are seeing a sizable uptick in demand for solutions to test transport networks. In fact, today it comprises well over one-third of our business — more than 5G infrastructure or application testing. Given the complexity involved and the high stakes at hand, NEMs are requesting urgent assistance with transport testing as they expedite offerings that must be ready for full-scale deployment in just 12-24 months.

Because transport technologies are being developed at the same time standards are being defined, testing assistance is being requested in areas that span functionality, scalability, and interoperability. While industry players are working in parallel, overall stability and a clear direction forward remain elusive.

Further adding to the complexity are requests to create test solutions not just for existing and evolving standards, but new technologies for delivering 5G transport, such as slicing packet network testing.

Transport Testing Takeaways

With transport-focused engagements comprising nearly half of Spirent’s 5G work, we are actively engaged with a range of customers globally. Following are key takeaways from these engagements based on our efforts in the field over the past year:

We can report with confidence that both vendors and operators are deeply engaged in projects to validate equipment and detailed strategies against new standards with plans for early interoperability testing. In particular, operators are leveraging end-to-end test solutions capable of emulating billions of devices to stress-test the transport infrastructure, since it is not feasible to do this on a live network.

Operators are building out data centers to support Cloud RAN and NFV, as well as network slicing test capabilities to help ensure the diverse bandwidth, latency, security and time synchronization required by 5G applications. This includes network slicing transport standards testing and validation for mission-critical 5G applications, as well as fronthaul and backhaul protocol testing. This work is being done to help operators prepare the transport network and data center architecture for mass market deployments.

In 2020, the industry must put more focus on higher speeds (100/400G), throughput testing and network emulation to overcome interoperability and scalability challenges and help address competing 5G standards.

As networks prepared for 5G, the levels of synchronization accuracy required to enable new 5G distributed fronthaul applications increased exponentially. The associated standards are evolving to support these next-generation accuracy requirements for PTP (Precision Time Protocol) and SynchE (Synchronous Ethernet). Our own test equipment already supports transport equipment manufacturers as they seek to accelerate validation of 5G equipment with the highest accuracy testing to sub nano-second.

Transport 2020: A Look Ahead and What to Expect

A major industry shift is underway as an increasing number of top-tier operators begin to embrace open and virtual network infrastructure, including for radio. In late 2019, Vodafone went as far as to announce that it is putting its entire European footprint, which spans 100,000 mobile sites, up for a redesign based on open radio access network (ORAN) technology. The significance of this cannot be understated as the move has the potential to shake up the infrastructure market as we know it.

Manufacturers and operators will continue to be interested in highly scalable, open interfaces such as eCPRI and ORAN for 5G fronthaul, as well as SDN and network slicing for 5G transport. All of these will need to be tested to ensure they will meet performance, scalability, interoperability and high availability expectations.

As a result, we anticipate eCPRI and cRAN fronthaul protocols will become critically important throughout the remainder of 2020. For backhaul, we expect EVPN and Segment Routing, especially SRv6 adoption, to further increase, truly powering 5G network services and transport. We see SPN (Slicing Packet Network) playing a major role in enabling network slicing to meet the most demanding requirements of 5G applications.

However, these advancements won’t happen overnight. We are seeing 5G initially being deployed in dense urban centers. Upgrades will be implemented gradually: radio tower upgrades to 5G, followed by fronthaul network upgrades, backhaul network upgrades, then cloud edge upgrades.

Assurance and Automation

The race to expand 5G deployments and the NFV infrastructure that supports them is shifting more of the network to the cloud. Functions that used to sit in well-defined network locations are now being virtualized and deployed in any number of locations — from centralized data centers to the customer premises.

In previous network generations, operators were happy to put off assurance strategies until problems started showing up in the network. But too much is riding on 5G to follow the same timelines, especially with lucrative enterprise revenues on the table. Of course, testing every last aspect of configurations in advance of deployment would delay rollouts, given the complexity of these live, dynamic networks. Network slices, in particular, will change so often that manual troubleshooting won’t be able to keep up.

This means that while many aspects of networks must be assured prior to deployment, automated assurance technology that remains active in the live network is not a luxury, but a necessity. Operators and network equipment manufacturers will continue to work on verifying VNF functionality and performance in the lab, as well as making sure emergency and other services will work properly. Testing how well 5G VNFs interoperate with existing technologies like 4G and Wi-Fi will also continue to be on the radar.

For the 5G NSA operational network, service providers are in the early stages of assuring services, validating the NSA network’s operational performance, and ensuring the NSA network co-exists properly with LTE networks.

With an onslaught of new and modified network slices, new devices, and frequent software updates, the 5G network is changing continually. It is changing so fast that the changes can’t be validated using traditional manual methods. An active assurance framework can automate the validation and management of all these dynamic changes. The new active assurance playbook sees operators evaluating service performance at turn up, checking critical services and links that have variable or no usage, seeing end-to-end views, and isolating problems anywhere in the network. This active assurance approach emulates real network functions, devices, and users, constantly testing networks to uncover issues by injecting highly realistic, synthetic traffic into the network.

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Spirent is seeing customers embrace end-to-end, automated assurance to meet customer expectations for quality experiences. They are specifically focusing on network slicing, service quality monitoring, change management, and fault isolation.


This article is an excerpt from the new report 5G: What To Expect In 2020. For more information and to download the report, please visit

About the Author

Stephen Douglas

Stephen Douglas is Head of 5G Strategy, Spirent. With over 24 years of experience in telecommunications, Stephen has been at the cutting edge of next-generation technologies, and has worked across the industry with service providers, network equipment manufacturers, and start-ups, helping them drive innovation and transformation. Stephen currently head’s Spirent’s 5G strategy and represents Spirent on a number of national advisory boards. For more information, please contact or visit