50G PON: Next-Generation Universal Broadband

A guest post from Emir Halilovic, Research Director of Telecom Technology & Software Group at GlobalData.

About the author

Emir focuses on optical transport layer products and technology, including WDM, OTN switching, OADMs, packet optical networking, and converged IP/optical platforms. He has a particular interest in how deep changes in networks, like 5G, NFV, and SDN, affect the evolution of transport products and technologies.

Operators’ broadband infrastructures have proven to be a critical lifeline over the past decade – so much so that numerous governments and private investors around the world started to significantly accelerate investment into broadband network development and deployment.

Overwhelmingly, the center of this increased focus on broadband converges on fiber access infrastructure. More precisely, the vast majority of all new broadband deployments and overbuilds are focusing on passive optical networking (PON), because it combines excellent performance in terms of bandwidth and connection quality, cost efficiency, and support for a future technology roadmap.

But even as the great majority of global operators continue to deploy and densify their PON footprints – today predominantly XG(S)-PON – the needs stemming from upcoming applications in the residential, SME, enterprise, and wholesale market segments are starting to define the future capabilities of next-generation PON technology as a foundation of operators’ broadband business well into the 2030s.

The requirements stemming from next-generation broadband use cases and applications roughly define the following characteristics for future PON:

• Ample and symmetrical bandwidth: Broadband usage in most markets is evolving. Beyond already the traditional growth in sheer volume of data transferred, applications like the metaverse, VR, AR, ultra-high-definition video streaming, game streaming, cloud gaming, and two-way video communication require operators to increase the downstream and upstream bandwidth of their broadband products in line with customer perception of connection bandwidth as a guarantee of a high-quality experience. When the needs of SME, enterprise, or wholesale users are considered, it quickly becomes evident that current mainstream products offering around 1-Gbit/s speeds may become insufficient to satisfy growing bandwidth demand in the foreseeable future.
• Controlled latency, timing, and synchronization: Another common trait of consumer and enterprise use cases and applications that drive forward bandwidth requirements are their need for precisely control connection quality parameters, like latency. Along with the demand for increased and controlled connection quality, wholesale use cases that operators increasingly use to justify next-gen broadband investment, like mobile transport, require precise timing and synchronization.

• Advanced QoE control mechanisms: Next-generation PON technologies need to provide operators with real-time visibility into all connection parameters and ways of tightly controlling them. This is primarily given by the increasing complexity of broadband use cases spanning different use segments. In some cases – like households which also serve as home offices – per-application control of QoE may be needed.

Faced with this set of requirements, the telecoms industry – operators and their ecosystem of equipment and component vendors – have reached a consensus on 50G PON as the next-generation platform for broadband development. The technology, standardized by ITU-T in September 2021, brings a set of features closely aligned with evolving requirements of telecoms operators and their clients:

• Significantly increased bandwidth and options for symmetrical access: 50G PON, as defined in the ITU standard, offers options for broadband access of up to 50 Gbit/s symmetrical bandwidth on OLT ports, providing operators with significantly higher capabilities than today’s mainstream XG(S)-PON, which provides a maximum of 10 Gbit/s. In practice, 50G PON can be used to provide multiple types of broadband services from the same node, tiered by bandwidth and symmetricity, to satisfy different types of customers and applications.
• Low latency, timing, and synchronization: 50G PON has been designed to provide significantly lower system latency than legacy and currently mainstream PON technologies, making it suitable for use cases where low latency is a key feature. Chief among those is the use of PON for small-cell mobile (predominantly 5G) transport, but other applications – like cloud gaming in the residential segment or enterprise cloud applications can benefit from this feature. Implementation of timing and synchronization mechanisms for mobile transport have also been demonstrated on 50G PON platforms, which makes the technology suitable for 5G (and possibly 6G) small cell deployments.
• Legacy service coexistence: The importance of legacy service coexistence has led to 50G PON design options allowing for deployment of the new technology concurrently with existing GPON or XGS-PON. Most operators will likely choose the path of XGS-PON and 50G PON coexistence, however for some coexistence with GPON may be an option.
• Re-use of existing passive infrastructure: 50G PON has been trialed over already deployed ODN (optical distribution network) infrastructure and should provide around a 20-km reach, which is in line with currently used PON technologies.

Taken together, this new set of capabilities can enable operators to significantly expand their broadband business with support for multiple different use cases over the same infrastructure, continuing the trend already visible with mature technologies like XGS-PON. However, 50G PON capabilities, especially in terms of low-latency and latency-differentiated traffic, are more advanced, making it much more capable in mobile transport roles and opening new ways for operators to monetize broadband infrastructures. The same can be said for enterprise use cases or select consumer application types where low latency can be of special interest to clients, like with cloud gaming or the metaverse in the future.

Related: The Role of Connectivity in Building the Metaverse

Although 50G PON is currently in its infancy, the industry support behind it is already formidable. Operators in China, the world’s largest FTTx market, consider 50G PON to be their future broadband platform, while several global operators like Orange, Swisscom, and others, have voiced their support for 50G PON. Beyond ITU-T standardization, the 50G PON ecosystem of solutions is growing, which is especially important considering the technology still needs to evolve to achieve its full potential. This relates to the development and commercialization of key solution components, like DSPs, LDPC encoding, and transceiver components. These are likely to benefit from development in adjacent fields, like radio access, high-speed optical transport, and data center networking, respectively.

Considering the key features of 50G PON systems as designed and demonstrated, the capabilities it brings can be viewed as a key component of operators’ efforts to expand their broadband business and ensure its growth in the foreseeable future. Unlike its predecessor technologies, it is designed to support multiple use cases, and the design envisions operators deploying 50G PON to satisfy the needs of multiple customer types. With already established customer support, ITU backing, an expanding component and supplier vendor ecosystem, and early commercial deployments planned for 2024, the mass introduction of 50G PON will mark the transformation of FTTx into next-generation universal broadband infrastructure.

It will bolster operators’ fixed and mobile access business and customers to enjoy qualitatively better broadband experience.

More on 50G PON

• 50G PON’s Major Role in Driving Society Forward [blog post]
• Why 50G PON Looks Like a Clear Winner vs 25G [blog post]

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Disclaimer: Any views and/or opinions expressed in this post by individual authors or contributors are their personal views and/or opinions and do not necessarily reflect the views and/or opinions of Huawei Technologies.