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5G Transport Gets Real with Time-Sensitive Networking

Jon Baldry

November 19, 2019
By Jon Baldry
Director, Metro Networking

“Good things come to those who wait,” so the famous saying tells us. 5G certainly holds the promise of great changes, but we are just as certainly going to have to wait to see them as the technology evolves. As we’ve discussed previously here on the Infinera blog as well as in the media, 5G will ultimately bring great advances to almost every aspect of our lives, but will take time to evolve as we move through its various phases.

We’ve discussed how the initial phase of 5G services focuses on the enhanced mobile broadband (eMBB) use case, where the technology focus is on enhancing radio access networks (RANs) to support new higher-bandwidth 5G devices, and also how the later phases start to introduce more advanced 5G services, with a corresponding impact on the rest of the mobile network.

From a mobile transport perspective, phase 1 has little impact. Most mobile operators are able to carry these first 5G services over their existing infrastructures as transport performance requirements are essentially the same as 4G, and even though 5G customers typically use more bandwidth, overall network traffic is still dominated by video traffic to 4G users. So, any 5G-related upgrades often just require a small increase in backhaul capacity in the network. From a mobile transport point of view, all the exciting action comes with phase 2 of 5G rollouts, where the core is upgraded to support new ultra-reliable low-latency communications (uRLLC) services. Many of these new services will require the backhaul network to be rearchitected into an X-haul network capable of supporting 5G fronthaul, midhaul, and backhaul traffic with lower latency and better synchronization support, while also introducing multi-access edge compute capabilities and network slicing. All this will take some time.

But mobile operators aren’t sitting back and waiting for phase 2 services to materialize – many are preparing their networks now, as the transport network needs to be in place before the first of these phase 2 services can be enabled. This week Infinera took an important step toward enabling these advanced 5G networks with the announcement of the availability of the company’s new EMXP-XH800 in the first quarter of 2020. Importantly to this discussion, the new device supports Time-Sensitive Networking (TSN), which is a key enabling technology for 5G X-haul networks. Earlier this year Infinera worked with Mobile World Live to conduct a survey on 5G Network Architectures, and the resulting report highlighted the importance of X-haul in network operator strategies.

TSN, and specifically its strict traffic prioritization and “preemption” capabilities, is important for X-haul networks as they allow more deterministic traffic paths through the network and allow devices to prioritize eCPRI fronthaul traffic. It does this by essentially pausing the transmission of a lower-priority frame that has already begun transmission when a higher-priority eCPRI frame arrives, which can help considerably with 10 GbE and 25 GbE interfaces.  A non-TSN switch would usually make a priority decision on which frame to switch next once it has completely finished switching the current frame, which would have a large latency impact on fronthaul traffic, especially when waiting for jumbo frames to finish transmission. TSN enables the device to switch and aggregate Ethernet and eCPRI traffic together, enabling operators to deploy X-haul networks capable of supporting parallel fronthaul, midhaul, and backhaul traffic.

While this device is getting a lot of interest from mobile operators and wholesalers, it is also getting good traction outside of the mobile space due to other new advantages the device has. Many other network operators are also pushing fiber and DWDM deeper into access networks to support higher capacity to the end user and better network/service performance. This means pushing high-capacity packet optical aggregation into locations that are space- and power-constrained, many of which are just street cabinets rather than the usual temperature-controlled environments needed for optical transport equipment. The EMXP-XH800 brings a step change improvement in density and low power consumption in a hardened device specifically designed to support 100G/200G coherent DWDM in street cabinet deployments with the front access, right-to-left cooling, and low noise that they require. As the EMXP-XH800 is an addition to the widely deployed range of EMXP units within the XTM Series, the device comes with a feature-rich software and full interworking with the rest of the range, enabling a vast array of deployment scenarios in many applications.

So, to close, we’ll be busy with 5G and other fiber deep aggregation applications for many years to come as new end-user services become available and the underlying transport networks need to evolve to support ever-tougher transport requirements. With the availability of the EMXP-XH800, we are making an important step to help network operators evolve their networks for those all-important phase 2 5G services. Throughout this year we’ve been heavily engaged with customers on the EMXP-XH800, so 2020 looks to be an exciting year as we start to roll this out in some of the most advanced optical networks on the planet.