400G: Building Bandwidth for the Next Lap

Anticipating an Explosion of Bandwidth Demand

Global bandwidth demand is on an unprecedented rise. In 2022 alone, the International Telecommunications Union (ITU) recorded 25% growth in international bandwidth usage, adding to a 33% compounded average growth rate that’s been steadily rising since 2017. 

For individual consumers, 1Gbps connectivity is now a norm while high-definition video has become ubiquitous in everything, from entertainment to security. The proliferation of fibre connectivity has also enabled exponential growth in the number of connected devices.

At the enterprise level, 10G ultra-broadband connectivity is becoming standard for enterprise campuses. More notably, cloud-first strategies and Artificial Intelligence (AI) and Machine Learning (ML) have become integral parts of the business landscape: according to Foundry research, 65% of IT decision-makers say their organisations are defaulting to cloud-based services when upgrading or acquiring new systems, with 57% of organisations surveyed are actively researching or piloting AI and ML technologies.

This proliferation of bandwidth-hungry technologies is expected to lead to rapid consumption of ports and leased fibre resources, driving the growth of metro and backbone networks as well as data centre interconnection for greater bandwidth.

Bandwidth Bottlenecks: Facing the Shannon Limit

However, meeting this demand in a cost-efficient way is getting tougher. Over the past decade, the preferred method to reduce network construction costs was through focusing on coherent transmission costs per bit. Innovation and improvements in phase modulation and coherent reception increased spectral efficiency by about 20% yearly, effectively reducing costs by enhancing single-fibre capacity. 

Now, the industry is facing development bottlenecks as capacity approaches the Shannon limit, the theoretical maximum rate of data transfer over a single channel. To achieve further significant reduction of costs, single-fibre capacity must be improved, to further maximise bandwidth without shortening transmission distance.

Within the enterprise market, organisations facing these limitations are turning to 100G and 200G as established solutions to meet current demand. Recent upgrades have seen 100G solutions deployed for metro networks and public services networks, but these are likely to reach their limits sooner rather than later. 

At the next level, 400G solutions are employed in backbone networks such as national information networks, Internet service provider (ISP) backbone networks and data centre interconnection. 

“For enterprises, deploying a 400G solution offers future-proofing as well as promoting the transition from Internet of Everything to Intelligent Connectivity of Everything,” says Chen Zeyu, Huawei’s Director of the Optical Product Marketing & Solutions Sales. “This will ultimately present more possibilities for the digital transformation of industries.” 

But to fulfil this potential, a 400G solution must fulfil two key criteria to be effective and cost-efficient:

• In terms of transmission performance, a 400G solution must be as stable and coherent as 100G and 200G networks, to fulfil long-haul and ultra-long-haul backbone transmission requirements. 

• In terms of cost management, the solution must be able to reuse existing fibre infrastructure and offer the potential for further reduction of per-bit costs.

Innovating for a next generation 400G solution 

With these requirements in mind, Huawei has developed its Next-Generation 400G solution based on three game-changing technological innovations:

The first innovation comes from employing the industry’s first GSC-FEC and Kerr non-linear compensation algorithm to achieve ultra-powerful transmission performance. Huawei’s 400G networks can achieve transmission distances 1000 kilometres further than the industry average, with 20% better performance. With overall transmission performance increased by more than 1 dB, the enhanced transmission capability approaches close to the theoretical Shannon limit.

Huawei’s second innovation is ultra-high component integration. In another industry first, a five-in-one coherent optical subassembly (COSA) integrates five components, including the optical amplifier, into a single optical component smaller than a fingernail. The resulting subassembly is a third of the industry-average size, consumes 50% less power, and offers a 90% reduction in connection loss compared to conventional solutions. 

The third innovation is the ultra-broadband optical amplifier. Huawei’s R&D engineers undertook more than ten thousand trials of chemical doping elements to stimulate L-band transmission capability and expand the spectrum. The innovative Super C+L solution offers double the attainable spectral resources and supports transmission of up to 240 wavelengths, 25% more than the industry average.

“Through these innovations, we are able to develop 400G solutions with optimal per-bit costs. Network construction costs can be reduced by up to 32% per bit, while achieving exceptional transmission performance,” explains Chen.