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Nokia Pushes Optical to the LimitNokia Pushes Optical to the Limit

The Shannon limit, that is, claiming its Photonic Service Engine 3 (PSE-3) chipset takes optical channels close to the maximum theoretical capacity.

March 6, 2018

4 Min Read
Nokia Pushes Optical to the Limit

Nokia has lit the annual optical speeds-and-feeds touch-paper ahead of next week's OFC event in San Diego with the unveiling of its Photonic Service Engine 3 (PSE-3) chipset, which, it claims, can take optical channels very close to the maximum theoretical capacity.

The vendor says the PSE-3 is capable of "maximizing the capacity and performance of every link" in optical networks run by communications service providers and web-scale giants, and those are capabilities that all data transport network operators are going to want as they seek to manage rapidly increasing volumes of traffic with greater efficiency (more automation) without incurring crippling costs.

Nokia claims its new digital signal processor (DSP) "enables maximum capacity over any distance and on any fiber," whether it's a metro, long-distance or even subsea route, and can achieve "optical fiber transmission capacity to very near the Shannon limit," which, based on bandwidth and "noise" characteristics, defines the maximum rate at which data can be sent over a communications channel without any errors. (For more on that topic, see this deep dive into the subject.)

They key to achieving such spectral efficiency is a modulation technique known as probabilistic constellation shaping, which is really hard to say even when sober. In a nutshell, probabilistic constellation shaping (PCS) automatically shapes signals (based on pre-defined policies) to best suit the characteristics of the installed fiber, resulting in optical wavelengths that have less interference and impairments and so enabling significant increases in the potential capacity of the fiber.

Nokia says its PSE-3 is the first chipset to implement PCS, which has been developed at Bell Labs, part of the Nokia empire. "It's been shown in labs, in tests, for years but this is the first time it has been put into silicon," says Kyle Hollasch, head of marketing for Nokia's optical business.

In fact, Nokia has already teamed up with Facebook to test PCS, this time last year, to quite dramatic effect. (See Nokia & Facebook Push Undersea Fiber to 32 Tbit/s.)

Now Nokia's getting closer to getting a commercial product out to market: Hollasch says the PSE-3 will be available for trials in the second half of this year and be commercially available in early 2019.

But now's the time to be shouting about it, obviously. "This is the final major breakthrough" in terms of spectral efficiency, reckons Hollasch of the chip that provides adjustable wavelength capacity from 100G to 600G. "I'm not saying there won't be incremental gains in the future but this will be the last big leap" in terms of performance advances, Nokia believes. "I hate to use the term Holy Grail, but…" adds the marketing man, whilst using the term Holy Grail.

It's more than just the capacity that the Nokia team is stressing, though: The flexibility afforded by the DSP's ability to figure out the best settings and the increased simplicity from the chip's inherent programmability are key selling points too. "Operations, planning, design -- these are all made easier. The chip has a lot of telemetry capabilities, so it can gather a lot of information about the network around it," notes Manish Gulyani, head of marketing for Nokia's IP and optical business.

And what about price? That's a bit more fuzzy: Gulyani talked about a lower total cost of ownership and a reduced cost per bit but, as with all advances, it will come with a price tag (at least initially) that will no doubt leave the vendor's current PSE-2 chipset looking like a bargain.

Nokia has a set of percentage-gain claims to attach to the PSE-3 too, such as: increasing capacity up to 65% compared with "currently deployed networks"; reducing power per bit by 60%; and the need for 35% fewer transponders in networks built with systems using the new chipset.

The exact figures used for such calculations weren't included in Nokia's official announcement but will, the company says, be examined and discussed during a session at OFC (Session W4A.6 on Deployable Transport Networks -- Wednesday March 14, Room 1A, 16:30 to 18:30).

So, is this as big a deal as Nokia is making out?

Don Frey, principal analyst for transport and routing at research house Ovum Ltd. , believes Nokia is "pushing the technology boundary, especially on the overall capacity by distance due to the probabilistic constellation shaping capability," and that the chipset will give the vendor "a leading position on getting the most bandwidth over long distance."

The development is "advancing the ability to get the highest capacity over a fiber cable. Where a carrier or a data center is fiber poor, this technology helps them to get more out of their fiber," adds Frey.

But the vendor should not rest on its laurels and will face a significant challenge in some use cases, notes the analyst. "I think for Internet content providers, Nokia is providing the leading solution that meets web-scale backbone and submarine needs. For metro and regional, I think the Acacia pico solutions may offer more density in a 1RU platform. Nokia needs to deliver it on time, as Acacia's solution is delivering prototypes now to system vendors."

Now, there's a talking point for OFC…

— Ray Le Maistre, Editor-in-Chief, Light Reading

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