BT’s Open RAN trial: A mix of excitement and pragmatism

“We in telecoms, we don’t do complexity very well.” So says Neil McRae, BT’s managing director and chief architect.

He was talking about the trend of making network architectures open and in particular the Open Radio Access Network (Open RAN), an approach that BT is trialling.

“In networking, we are naturally sceptical because these networks are very important and every day become more important,” says McRae

Whether it is Open RAN or any other technology, it is key for BT to understand its aims and how it helps. “And most importantly, what it means for customers,” says McRae. “I would argue we don’t do enough of that in our industry.”

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OFC highlights a burgeoning coherent pluggable market

A trend evident at the OFC show earlier this month was the growing variety of coherent pluggable modules on display.

Whereas a coherent module maker would offer a product based on a coherent digital signal processor (DSP) and a basic design and then add a few minor tweaks, now the variety of modules offered reflects the growing needs of the network operators.

Tom WilliamsAcacia, part of Cisco, announced two coherent pluggable to coincide with OFC.

The Bright 400ZR+ QSFP-DD pluggable form factor is based on Acacia’s existing 400ZR+ offering. It has a higher transmit power of up to 5dBm and includes a tunable filter to improve the optical signal-to-noise ratio (OSNR) performance.

Acacia’s second coherent module is the fixed wavelength 400-gigabit 400G ER1 module designed for point-to-point applications.

“I can understand it being a little bit confusing,” says Tom Williams, vice president of marketing at Acacia. “We have maybe five or six configurations of modules based on the same underlying DSP and optical technology.”

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Building an AI supercomputer using silicon photonics

•  Luminous Computing is betting its future on silicon photonics as an enabler for an artificial intelligence (AI) supercomputer 

Silicon photonics is now mature enough to be used to design complete systems.

So says Michael Hochberg (pictured), who has been behind four start-ups including Luxtera and Elenion whose products used the technology. Hochberg has also co-authored a book along with Lukas Chrostowski on silicon photonics design.

In the first phase of silicon photonics, from 2000 to 2010, people wondered whether they could even do a design using the technology.

“Almost everything that was being done had to fit into an existing socket that could be served by some other material system,” says Hochberg.

A decade later it was more the case that sockets couldn’t be served without using silicon photonics. “Silicon photonics had dominated every one of the transceiver verticals that matter: intra data centre, data centre interconnect, metro and long haul,” he says.

Now people have started betting their systems using silicon photonics, says Hochberg, citing the examples as lidar, quantum optics, co-packaged optics and biosensing.

Several months ago Hochberg joined as president of Luminous Computing, a start-up that recently came out of stealth mode after raising $105 million in Series A funding.

Luminous is betting its future on silicon photonics as an enabler for an artificial intelligence (AI) supercomputer that it believes will significantly outperform existing platforms.

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Can a think tank tackle telecoms innovation deficit?

The Telecom Ecosystem Group (TEG) will publish shortly its final paper that concludes two years of industry discussion on ways to spur innovation in telecommunications.

The paper, entitled Addressing the Telecom Innovation Deficit, says telcos have lost much of their influence in shaping the technologies on which they depend.

Source: Telecom Ecosystem Group

“They have become ageing monocultures; disruptive innovators have left the industry and innovation is outsourced,” says the report.

The TEG has held three colloquiums and numerous discussion groups soliciting views from experienced individuals across the industry during the two years.

The latest paper names eight authors but many more contributed to the document and its recommendations.

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The various paths to co-packaged optics

Near package optics has emerged as companies have encountered the complexities of co-packaged optics. It should not be viewed as an alternative to co-packaged optics but rather a pragmatic approach for its implementation.

Co-packaged optics will be one of several hot topics at the upcoming OFC show in March.

Placing optics next to silicon is seen as the only way to meet the future input-output (I/O) requirements of ICs such as Ethernet switches and high-end processors.

Brad Booth

For now, pluggable optics do the job of routing traffic between Ethernet switch chips in the data centre. The pluggable modules sit on the switch platform’s front panel at the edge of the printed circuit board (PCB) hosting the switch chip.

But with switch silicon capacity doubling every two years, engineers are being challenged to get data into and out of the chip while ensuring power consumption does not rise.

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Infinera’s ICE6 crosses the 100-gigabaud threshold

Coherent discourse 3

• The ICE6 Turbo can send two 800-gigabit wavelengths over network spans of 1,100-1,200km using a 100.4 gigabaud (GBd) symbol rate.
• The enhanced reach can reduce the optical transport equipment needed in a network by 25 to 30 per cent.

Infinera has enhanced the optical performance of its ICE6 coherent engine, increasing by up to 30 per cent the reach of its highest-capacity wavelength transmissions.

Ron JohnsonThe ICE6 Turbo coherent optical engine can send 800-gigabit optical wavelengths over 1,100-1,200km compared to the ICE6’s reach of 700-800km.

ICE6 Turbo uses the same coherent digital signal processor (DSP) and optics as the ICE6 but operates at a higher symbol rate of 100.4GBd.

“This is the first time 800 gigabits can hit long-haul distances,” says Ron Johnson, general manager of Infinera’s optical systems & network solutions group.

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Building the data rate out of smaller baud rates

In the second article addressing the challenges of increasing the symbol rate of coherent optical transport systems, Professor Andrew Lord, BT’s head of optical network research, argues that the time is fast approaching to consider alternative approaches.

Coherent discourse 2

Coherent optical transport systems have advanced considerably in the last decade to cope with the relentless growth of internet traffic.

Professor Andrew Lord

One-hundred-gigabit wavelengths, long the networking standard, have been replaced by 400-gigabit ones while state-of-the-art networks now use 800 gigabits.

Increasing the data carried by a single wavelength requires advancing the coherent digital signal processor (DSP), electronics and optics.

It also requires faster symbol rates.

Moving from 32 to 64 to 96 gigabaud (GBd) has increased the capacity of coherent transceivers from 100 to 800 gigabits.

Last year, Acacia, now part of Cisco, announced the first 1-terabit-plus wavelength coherent modem that uses a 128GBd symbol rate.

Other vendors will also be detailing their terabit coherent designs, perhaps as soon as the OFC show, to be held in San Diego in March.

The industry consensus is that 240GBd systems will be possible towards the end of this decade although all admit that achieving this target is a huge challenge.

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