Defining High Capacity: A Discussion of Cable Manufacturers

As published in the July Issue of SubTel Forum Magazine

By Stephen Nielsen
July 20, 2022

Given that the submarine telecoms industry has a history of more than 170 years of continuous development, it can be surprising how vague many concepts are as their actual definition doesn’t span the industry. What constitutes “Deep Water?” How long does a cable need to be to be “Long Haul?” For the purposes of this High Capacity Issue of Submarine Telecoms Forum, we asked the question “What is a High Capacity cable,” and discovered that the answer wasn’t so clear.

“The definition of high capacity is constantly changing,” said a representative of HMN Tech.

Along with HMN Tech, Hexatronic, Prysmian and NEC responded to a Q&A regarding the current state and future of the High Capacity cable manufacturing industry. All four are notable cable manufacturers in the submarine telecoms industry. There are currently seven primary cable manufacturers supplying the submarine telecoms industry: ASN, Prysmian, Hexatronic, HMN Tech, NEC, Nexans, and SubCom.

“Currently, one could argue that any repeatered cable containing 16 fiber pairs could be regarded as high capacity, but that’s a pretty arbitrary number, and doesn’t take into account the capacity of each fiber pair,” said NEC’s response. “Also, at the current growth rate of traffic demand, today’s notion of ‘high capacity’ will become more and more mainstream.” Similarly, Prysmian defines high-capacity as 48 fiber pairs for unrepeatered cables, and 16 for repeatered.

Alternately, the response by Hexatronic argues that a truly high-capacity cable would be “a submarine cable of 96 fibers or more.” This definition, however, could only be applied to the unrepeatered cables, given that current repeater technology can only handle roughly 24 fiber pairs.

This highlights a current large disparity in what could be considered high-capacity cable in unrepeatered vs. repeatered cables. HMN Tech can claim a maximum of up to 1000 fiber pairs in their unrepeatered cables while their repeatered maxes out at up to 32 fiber pairs. NEC currently has cables with 24 fiber pairs in production, and state that “further improvements to this number are very close to market.” Hexatronic cables can go up to 192 fibers for their unrepeatered systems.

“A high-capacity cable means the cable can meet customers’ current capacity requirements and support capacity expansion to meet increasing bandwidth requirements to the greatest extent in the future 25-year lifespan of cable,” said HMN Tech’s response. “Technically, the recent demands are well satisfied by the advanced technologies, like SDM wet plant solution, and optical fibers with large effective area and low loss.”


Planned capacity worldwide is expected to increase by 110% over the next five years according to public information included in the Subtel Forum Database. Alongside new cable builds, older systems are implementing upgrades to expand capacity and extend system lifespan. All of which highlights that innovation and continued development of cable technology will be key to keeping up with ever-increasing demand for capacity and the eventual failure of older systems.

“There doesn’t seem to be any slow-down in the subsea capacity demanded by the market.,” responded NEC. “Real-time services like AR, VR and the metaverse in general are set to continue to drive end user demand, supported by rollouts of 5G and gigabit fiber access. Experimental trials of 6G are planned, which will further fuel higher subsea capacity needs.”

In that light, companies were asked about the future of high-capacity cable development. According to Hexatronic, an invention coming down the line will be a new type of fiber that will increase capacity without any major change to the size of the cable. Prysmian predicts the advancement of higher fiber densities within cables.

HMN Tech sees that and more coming, as the industry may need to change along with the innovation of new technologies. “First, 32fps high fiber count SDM solution will open the Petabits era and can meet the higher capacity requirement with 5G, Data center and stream media flourishing.” Additionally, they expect that single-mode fibers will be reduced in size and cladding diameter of fibers will also be minimized to increase the amount of fiber pairs without increased cable size.

An increase in automated computer monitoring will be another major step in how standard cable systems are run. “Intelligent analysis and management NMS is desired to use AI algorithms to predict network performance fault trends and carry out intelligent fault location functions to help customers predict network faults and prevent faults in advance, ensure the quality of communication services, and realize AI-based predictive maintenance.”

This would be in conjunction with the more flexible network topology and maintenance management: “A variety of optical switch BU, hot switching function, and WSS ROADM enhance the flexibility and robustness of network. Power efficiency is critical for power-constraint HFC SDM [high fiber count] system, which requires stronger power supply of PFE and higher work voltage of wet plants, thus, cable capacity and power efficiency should be balanced to obtain the optimal solution,” responded HMN Tech.

Finally, HMN Tech predicts further developments in SMART cables: DAS technology which uses fibers as “sensors” to detect vibrations. “With the forward development of technology, various types of real sensors, such as acceleration sensor, temperature sensor and pressure sensor can be added inside or outside RPT to collect more comprehensive information and help us explore the situation of the ocean better.”

Beyond the topic of developing technologies to support capacity demand, the subject of sustainability has been a significant one in all parts of the submarine telecoms industry, including cable manufacturers. “For the ICT industry, sustainability means a communication system is designed, manufactured, managed, and used in a way that minimizes environmental impact and meets the aims of sustainable development,” responded HMN Tech. Hexatronic’s response agreed that for cable manufacturers, sustainability means a low climate impact, sustainable supply chain, and strong business ethics.

That said, according to HMN Tech, cable manufacturers, don’t really need to go out of their way to support sustainability: “Compared with other ICT equipment (like data center), subsea cable transporting 99% of internet data is one of the most environment-friendly digital infrastructures with negligible carbon emission, according to the relative research,” responded HMN Tech. “This is good news for the world that the significant internet trunk meets sustainable development. Submarine cable is supposed to become a major communication system to be recommended based on its green advantages.”

So, to ask again: What is a High Capacity cable? Well I guess that all depends.

About the Author

Stephen Nielsen is Editor at Submarine Telecoms Forum and possesses more than 10 years’ experience in examining submarine cable systems. He has previously supported blogging and streaming at various PTC and SubOptic conferences. He is also a 6th Grade English Teacher and a former Finalist for Society of Professional Journalism’s Mark of Excellence Award.

He was previously employed by Winchester Star newspaper and Capital News Services, and is an American citizen based in Sterling, Virginia USA.

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