By Huang Haifeng

In the digital era, fifth-generation fixed networks (F5G) represented by all-optical technologies such as 10G passive optical network (PON) have built a foundation for digital economy development.

Looking into the next two to five years, the time has come for access networks to move from gigabit to 10Gbps. Booming new applications, such as generative AI, metaverse, AR/VR, and industrial Internet, require networks that feature higher bandwidth, lower latency, and higher reliability. This not only poses new requirements on the bandwidth and latency of access networks, but also requires operators to upgrade their networks from gigabit to 10G.

How to build all-optical access networks for the 10Gpbs era has become a key concern of operators. Nowadays, China plays an important role in the development of the optical access industry. According to opinions of major operators on all-optical access development, 50G PON has stood out as a key technology recognized by the industry to support all-optical access in the 10Gbps era. The space is huge, and the time is now to roll out 50G PON.

Huge Space: 50G PON Becomes the Cornerstone of the 10Gbps Era

Why do we need 50G PON in the 10G era? This is because 50G PON has the following advantages:

First, 50G PON is more advanced in technology. 50G PON uses single-fiber bidirectional transmission and can be upgraded from and deployed based on existing PONs. It is a next-generation PON technology standard chosen by ITU-T. According to industry experts, compared with 10G PON, 50G PON provides five times higher access bandwidth, lower latency and jitter, higher network protection and security, and smooth evolution from GPON and 10G PON. In addition, it is compatible with existing optical distribution networks (ODNs) to protect operators’ investment to the maximum.

Second, 50G PON supports more diversified service scenarios. According to ETSI’s vision of Fiber to Everywhere, 50G PON not only improves bandwidth, but also supports full-service bearing, low latency, and intelligence. It can serve diversified service scenarios such as home, government and enterprise, campus, industrial Internet, and cloud access. For example, in the campus Wi-Fi 7 access and aggregation scenario, the backhaul capability must exceed 10 Gbps to better utilize the rate and coverage advantages of Wi-Fi 7. A single 3D CT machine in a hospital requires 1–10 Gbps bandwidth to upload massive scanning data in real time for diagnosis. At the same time, immersive XR will provide virtual digital interaction for home entertainment and online enterprise collaboration. These scenarios have much higher requirements on bandwidth and latency. 50G PON is the right choice to meet these new service requirements.

Finally, 50G PON is widely recognized in the industry. In the past, it was disputed regarding whether 10G PON will evolve to 25G PON or 50G PON. LightCounting, a market research institute in the optical communications industry, believes that driven by the Chinese market, 50G PON will become an obvious winner compared with 25G PON in terms of total shipment from the early stage of large-scale deployment of next-generation PON. At the 2022 China Optical Network Seminar, Mao Qian, Honorary Director of the Optical Communication Committee of the China Institute of Communications and Chairman of the China FTTH Forum, pointed out that 25G PON transition is time-consuming and costly, and cannot support too many 10G users in the future. 50G PON is a better choice.

The Time Is Now: Mature Industry Chain and Wide Recognition from Operators

Since 50G PON has become the cornerstone of the 10Gbps era, is it the right time now to roll it out? In this regard, we need to consider the industry chain and operator recognition of 50G PON.

On the one hand, the 50G PON industry chain is mature in standard, optical modules, and commercial solutions.

First, the 50G PON standard is mature. In September 2021, ITU-T officially released the 50G PON standard as the only standard for next-generation PON after 10G PON, laying the foundation for the evolution of broadband services from gigabit to 10Gbps.

Second, commercial 50G PON optical modules are available. Accelink and Hisense Broadband have launched 50G PON optical modules fully compatible with the existing PON architecture.

Third, Huawei, as an industry leader, is dedicated to promoting 50G PON. During Mobile World Congress 2019, Huawei released the world’s first single-wavelength 50G PON prototype and cooperated with multiple major operators to complete verification tests. At Mobile World Congress 2023, Huawei released the world’s first 50G PON commercial solution.

On the other hand, 50G PON has been widely recognized by global operators.

First, we can see this from the 50G PON publicity by China’s three major operators.

China Telecom has been deeply engaged in 50G PON for many years and regards optical access as an important part of China Telecom’s cloud-network synergy. In 2016, China Telecom started the pre-research of the next-generation PON technology, jointly initiated the 50G PON standard in ITU-T, and led the architecture and requirement standard G.9804.1 as well as the G.9805 standard for multi-generation PON coexistence. China Telecom also proposed the solution for the coexistence of 2–3 generations of PONs. In March 2021 and August 2022, China Telecom and Huawei jointly completed 50G PON prototype verification by phase on key features such as power budget, rate, and wavelength. The results showed that Huawei’s prototype support smooth evolution from different PON systems on operators’ live networks to 50G PON. China Telecom plans to carry out technical research and live-network experiments in the next two to three years, actively explore applications in campus and backhaul fields, explore the business value of 50G PON in various industries, and work with partners to promote the development and application of 50G PON technologies and prosper the ecosystem.

China Mobile believes that the core technical architecture of the next-generation optical access network is the 50G PON+FTTR intelligent collaboration architecture, and proposes three technical development concepts: improving all-optical access performance, enhancing all-optical gigabit seamless coverage, and introducing intelligent collaboration. China Mobile pointed out that the low latency and network slicing features of 50G PON will support more service scenarios, including home and enterprise broadband services, integrated 5G small cell backhaul, and vertical industry applications. At the 2022 China Mobile Partner Conference, China Mobile Research Institute and industry partners released the NGOAN Technology Development White Paper. In addition, China Mobile is the editor of the core standards of the 50G PON physical layer. It has made many technical breakthroughs and innovations in fields such as receiving and sending with a high power budget, low latency, and multi-rate equalization. In addition, China Mobile takes the lead in completing live-network prototype experiments with industry partners.

China Unicom believes that after 10G PON, the PON industry will be converged in the 50G PON defined by ITU-T. 50G PON can meet the development requirements of innovative 10G services. In 2021, China Unicom released the CUBE-Net 3.0 network architecture and listed 50G PON as a key technology for ultra-broadband premium fiber access. In October 2022, China Unicom and industry partners jointly released the F5G Advanced Industry White Paper, which states that 50G PON is a key technology that supports 10Gbps access. Currently, China Unicom focuses on 50G PON compatibility and live network verification, FTTR fiber extension, edge computing capabilities, intelligent O&M to ensure service quality, and new intelligent computing access networks. In addition, China Unicom actively participates in standard activities to draft and release the related standards. According to China Unicom’s evaluation, more new services require intelligent operation, and ubiquitous access. 50G PON supports smooth upgrade from gigabit to 10Gbps based on live ODNs, and can serve as the foundation for ubiquitous all-optical access.

Second, leading operators outside China are also optimistic about the future of 50G PON. Emir Halilovic, Research Director of GlobalData’s Telecom Technology and Software Dept, believes that 50G PON is designed with key features that support operators’ broadband service development and meet application requirements in various scenarios. In addition, global top operators, such as Swisscom, Orange, and Telefonica, have clearly chosen 50G PON as the next-generation PON.

Conclusion: 50G PON Is Clearly the Right Choice for Next-Generation PON

Based on the preceding analysis, we find that 50G PON is ready in terms of standard research and formulation, industry chain development, and operator support. 50G PON is the direction of future PON technologies. Now it is the time for global equipment vendors, operators, and partners in the industry chain to team up and join hands, to build an all-optical base for intelligent IoT, for a more prosperous digital economy, and for a better life using 50G PON.