by Don Reckles, Fixed Networks, Nokia
Cable operators are facing pivotal decisions: whether to continue investing in their legacy hybrid fiber-coaxial (HFC) DOCSIS networks, and what technology to deploy in new builds. Nearly all are building out greenfield areas with fiber-to-the-home (FTTH), and many are thoughtfully overbuilding themselves in brownfield areas, typically with XGS-PON. But the most strategic will go further, incorporating 25G-PON in their upgrade.
25G-PON offers more than just bandwidth. It provides an immediate path to differentiated services, higher average revenue per user (ARPU), and long-term network flexibility. For cable operators feeling pressure from fiber overbuilders, telcos, municipalities, and fixed wireless providers, 25G-PON can help reclaim a competitive advantage.
The Limits of DOCSIS and HFC
Cable’s HFC networks, and generations of DOCSIS that extracted more performance from coax, have served well. But the limits are becoming evident. Cable subscriber growth has slowed since 2021, turning negative with consistent net losses since late 2023 (MoffettNathanson). Consumers are increasingly opting for higher-performing FTTH or lower-cost fixed wireless services.
Cable operators are now evaluating options for their existing plant: incremental upgrades with DOCSIS 3.1 Plus, DOCSIS 4.0 (Extended Spectrum or Full Duplex), or a full migration to FTTH.
A convincing case exists for FTTH based on the technological merits of fiber and Passive Optical Networking (PON). But an even stronger case lies in the business opportunities and competitive advantages that come from converging higher ARPU services—such as premium-tier residential and enterprise services—on the same fiber as standard residential offerings.
XGS-PON is the foundation, but not the finish line
The PON technology being most widely deployed today is XGS-PON, which delivers symmetrical 10 Gbps capacity. XGS-PON is ideal for meeting the growing demand for gigabit and multi-gigabit residential services. It is also well suited for supporting business services, mobile transport, smart cities, and more.
One of the greatest advantages of XGS-PON is that it can be easily extended to 25G PON, unlocking even more opportunities.
Why 25G-PON should be in the plan
1. Leapfrogging Competitors
In overbuilt markets, 25G-PON helps cable operators regain performance dominance, leapfrogging XGS-PON-based rivals. In areas not yet overbuilt, cable operators can send a deterrent signal, claiming the high ground with a top-tier offering, discouraging future encroachment.
2. Delivering True 10G Services
Although XGS-PON delivers 10 Gbps in theory, real-world throughput is about 8.3 Gbps due to network overhead, Forward Error Correction (FEC), and other factors. In contrast, 25G-PON delivers around 21.5 Gbps, enabling operators to cost-effectively offer true 10G services and realize monetization in enterprise, mobile transport, super-premium residential, and wholesaling.
3. Creating a New Differentiator
Cable operators have historically differentiated with bundled video, a service in sharp decline. U.S. cable video subscriptions have dropped approximately 25% since 2018, driven by streaming alternatives. 25G-PON offers a new differentiation: performance leadership. Higher-tier symmetrical services offer the new “stickiness” bundles once provided.
But what about 50G PON?
With early 50G PON products being introduced, cable operators may wonder whether they should wait instead of deploying 25G. The decision will depend heavily on the business case – what is the cost to deploy the technology and how much revenue will it generate?
25G PON is a mature technology and has dropped to a price point suitable for mass market deployment. It reached this point quickly because 25G leverages components widely used in the massive data center ecosystem for years. 50G PON requires new technology, and that comes at higher cost. Excluding China, 50G will be 3x more expensive than 25G for 2x more bandwidth, and remain more than twice as expensive until at least 2030 (Omdia).
While 25G is being deployed commercially today, initial 50G solutions are best suited for trials and early tactical implementations. 50G PON technology will need to mature and be optimized before it is ready for mass deployment, and that will take a few years.
Summing up, for high multi-gigabit services up to 20 Gbps, 25G PON is optimal in terms of bandwidth, cost, power efficiency, and ease of deployment. Operators with a business case for services greater than 20 Gbps before 2030 can rely on 50G, and evolve to 100G PON after 2030.
Coexistence makes 25G a smart step and paves the way to 50G
Perhaps most importantly, operators don’t have to choose between 25G and 50G. XGS-PON, 25G-PON, and 50G PON were designed for coexistence. They operate on different wavelengths, allowing multiple generations of PON to share the same fiber. Operators can deploy XGS and 25G today and add 50G later when the technology matures and the business case aligns.
The Path forward
25G-PON offers a low-risk, high-reward path to performance leadership. It complements XGS-PON, expands service potential, and sets the stage for 50G. As cable operators weigh their next moves, they should not just ask what is technically possible, but what is strategically wise. The future is fiber. The edge goes to those who make the most of it now.