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Indian Networks and Super C – A Perfect Match?

Suman Prasad

October 25, 2023
By Suman Prasad
Senior Director Sales and Business Development

Indian telecom operators are undergoing major transformation. Investment in optical transport networks is on the rise, driven by insatiable demand from consumers and internet content providers (ICPs) as more data centers are built and more content, compute, and storage are regionalized in and around India. We see this transformation in subsea networks, where traffic is brought onshore from the United States and the rest of the world. Publicly announced subsea cables that will land in India in the next few years include 2Africa Pearls, SEA-ME-WE 6, India-Asia-Xpress (IAX), India-Europe-Xpress (IEX), and Trans Europe Asia System (TEAS).

We also see transformation in terrestrial networks, where we need to increase capacity between existing data centers and cost-effectively deliver day-one connectivity for new ones. Earlier this year, Equinix announced a $42 million investment to launch its fourth data center, MB4, in Mumbai by the end of the year. Also in 2023, Reliance announced a $122 million collaboration with Brookfield to build new data centers in India. Although data centers are increasingly distributed throughout India, with nearby submarine cable landing stations, Chennai and Mumbai are home to the largest data center investments in the country.

So, how can telecom operators deliver cost-effective high-capacity, scalable optical transmission solutions for terrestrial networks that span hundreds and thousands of kilometers between cities and data centers across India?

To answer this question, we need to start with some common attributes of Indian telecom networks. First, Indian networks in many cases utilize leased fiber. With strong capacity demand outpacing new fiber builds, some service providers are now collaborating with Indian utility companies to lease extra fiber pairs that were previously installed for their private networks along their rights of way. The second attribute of Indian fiber networks is that they tend to have high fiber repair margins to accommodate frequent splicing.

So, with frequent use of leased fiber and higher fiber repair margins, what’s the best way for telecom operators to meet the growing capacity demands of consumers and data center operators alike? We believe it’s time to introduce Indian terrestrial networks to Super C optical line systems and the latest generation of coherent optical engines. This combination may just be a perfect match.

For years, the optical industry has been able to rely upon evolutions in coherent optical engines to increase spectral efficiency – that is, to transmit more bits per usable spectrum on each fiber pair. However, today’s 800 Gb/s-per-wave optical engines like Infinera’s dual-wave ICE6 and the upcoming 1.2 Tb/s-per-wave ICE7, announced earlier this year, are inching ever closer to the Shannon limit, or the upper bound for maximum spectral efficiency. In addition, higher fiber repair margins work against maximizing spectral efficiency as optical engine modulation rates need to be reduced to close link budgets and maintain the targeted optical signal-to-noise ratio (OSNR) for error-free transmission throughout the transmission lifecycle.

Infinera CHM6 and CHM7This brings us to Super C. Super C of course refers to the transmission spectrum where coherent DWDM wavelengths operate on the fiber. Expanding the transmission spectrum is not new. The extended C-band that operators use today was expanded to 4.8 THz from 4 THz, and before that from the original 3.2 THz C-band almost 20 years ago. Just like a highway, increased spectrum means more lanes for more traffic, or put another way, increased transmission capacity per fiber pair. Super C expands the usable spectrum to 6.1 THz – a 27% increase. But why haven’t we done this sooner? Super C has not been broadly pursued until now for two reasons – non-uniform performance or amplifier gain across the entire band and increased costs. However, with today’s advanced technology and some creative engineering, we can achieve cost-effective uniform performance across the Super C-band – as seen with Infinera’s GX Series compact modular platform. Overall the Infinera solution including Super C can make an extremely attractive alternative to 9.6 THz C+L solutions, thereby resulting in better total cost of ownership for service providers.

Super-C and Super-L spectrum expansion

By increasing the capacity on each fiber pair, telecom operators can deliver more transport services while avoiding the incremental cost of leasing additional fibers – which translates directly to reduced costs for their transport networks.

Infinera is also applying a similar engineering approach to the L-band. The L-band is an adjacent portion of the fiber spectrum that was traditionally deployed by Japanese operators but is now deployed as part of the combined C+L-band in networks predominately serving ICPs. Just like Super C, Super L extends the L-band from 4.8 THz to between 5.5 THz and 6.1 THz. With a feature-rich optical line system and advanced coherent optical engines, telecom operators can cost-effectively deploy across Super C, and once that spectrum is exhausted, they can virtually double their fiber capacity by seamlessly upgrading to Super C +  Super L – all while avoiding the increased cost associated with leasing incremental fiber pairs.

Indian telecom networks are on the move – driven by insatiable consumer demand and the increasing presence of internet content providers and data centers. Considering some of the common attributes of Indian networks, we think the time is right to introduce Indian networks to Super C and Super L optical line systems and coherent optical engines. We welcome the opportunity to further explore if this match is right for you.