Is 5G challenging optical network infrastructure?

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“Fiber optics are elementary for 5G.” That’s a statement made in many blogs and articles over the past twelve months. Seen as a key enabling technology for successful initial 5G rollouts, major upgrades to optical network infrastructure have been widely predicted, fueling the optical transport network market in the near term.

Recently, though, popular industry news outlets, analyst opinions and presentations from industry insiders have created the impression of a much more conservative approach. Cignal AI states that, despite early claims that the optical network must be upgraded to realize the capabilities of 5G, network operators are instead building the radio network first and updating the optical network only when needed. A recent post on Light Reading summarizing an OFC panel discussion titled “5G Applications and Networks: Real World Operator Case Studies” revealed that operators are not giving vendors too much to be excited about.

Is it really the case that 5G is going to matter that little to the optical transport network over the next few years? Despite all the excitement about 5G and early deployments already happening across the globe?

As in many cases, this is a matter of perspective. Clearly, mobile network operators must invest a significant amount of their budgets to acquire new spectrum and rollout the 5G RAN. There is obviously little money left for a complete overhaul of their RAN connectivity. This challenge is amplified by the fact that there is no real new revenue and little need for additional bandwidth resulting from initial installations. At best, we will see upgrades and additions to the optical network triggered by RAN extensions already happening on a regular basis with 4G.

Having said that, 5G RAN technology is challenging optical transport in quite a few areas from a solution perspective. The most obvious challenge is capacity when moving from a traditional backhaul to a fronthaul- or midhaul-centric architecture. Industry sources have revealed a sharp increase in demand for 10Gbit/s and 25Gbit/s eCPRI pluggables consumed by SK Telecom’s 5G rollout in South Korea – clear evidence that today’s optical networks can’t cope with the new traffic volumes. And this transition will happen globally at some point.

But there’s more than the need for bandwidth. To enable the service innovations that are expected in the future, optical connectivity must have much more demanding latency and jitter profiles. Real-time services, location-based services, mission-critical services, the internet of things – a wide portfolio of ideas for new applications that will not only demand better performance from the RAN but will also have a substantial impact on the underlying optical network. Service innovations might not be the initial target of many 5G rollouts, which are more likely to focus on improved coverage and relief for other weaknesses in today’s mobile network infrastructure, but they certainly do feature in every mobile network operator’s plans.

Presumably the biggest challenge for optical transport in 5G RAN connectivity applications is cost. RAN connectivity is a very cost-sensitive application. The demand for substantially more capacity, the need for better performance to enable future mobile applications and the tremendous amount of connections needed to interconnect cell towers and small cells call for new technology concepts. Passive optical network technology combined with superior operational simplicity is considered as one of the prime candidates. 

It may be that the initial phase of 5G rollouts around the world takes place without substantial impact on optical networks. What’s coming with the second phase, after mobile network operators have addressed the shortcomings of today’s networks with 5G technology, will however create a major technology shift in optical RAN connectivity networks. 

Operators will need to be ready. The time to prepare is now.


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