By Brian O'Neill, CommScope VP, Access Network Solutions

Today and in the near term, service providers (SPs) find themselves with an unusual technology landscape, both diverse and flexible, when considering the evolution of their hybrid fiber/coaxial (HFC) networks. Historically, SPs' access networks have advanced along at a regular, orderly upgrade cadence in step with evolving standards. DOCSIS® 1.0 was published in 1997, 2.0 in 2002, 3.0 in 2006 and 3.1 in 2013. These advances have come at regular intervals and involved specific upgrades to support them along a single technological path.

However, with DOCSIS 4.0, published in 2019, that once straight and narrow path splits, diverges and reconnects in ways that other standards have not. For SPs, this is actually good news, as this diversification offers greater flexibility in how they migrate their networks to (ultimately) unified DOCSIS 4.0. The most likely destination for SPs in this cycle, unified DOCSIS 4.0 integrates both ESD and FDx DOCSIS 4.0 technologies-meaning SPs can adopt either as an intermediate step without worrying about being frozen out of the ecosystem.

First, we need to summarize the different standards involved. ESD, or extended spectrum DOCSIS, uses orthogonal frequency division multiplexing (OFDM) to provide 10 Gbps downstream and 6 Gbps upstream and low network latency. FDx, or full duplex DOCSIS, delivers symmetrical multigigabit upstream and downstream speeds which is ideal for video conferencing and other applications that require a wide pipe in both directions, with a particular dependence on fiber connectivity. Both ESD and FDx are part of the overall DOCSIS 4.0 standard, but their specifications prevent them from interfacing directly-meaning SPs must select deployments that best meet their requirements.

From this, one may expect this divergence to be a problem, like choosing between VHS and Beta videotape standards. Fortunately, unified DOCSIS 4.0 incorporates both, so no SP will find itself stuck in an infrastructure dead end-and this is what makes the unusual diversity of current options such a boon for SPs in 2025 and the years following. It empowers early adoption of DOCSIS 4.0's immense spectrum without forcing a wholesale network upgrade all at the same time, a particularly worthwhile benefit for Tier 2 and Tier 3 SPs who prefer not to absorb the cost and inventory requirements up front.

In addition to ESD and FDx, D3.1Enhanced, (D3.1E), offers an even more economical way for SPs to leverage a substantial portion of DOCSIS 4.0's downstream speeds right away, via CMTS software upgrades and field deployments of next-generation CPE devices, by adding additional OFDM channels to mid-split and high-split DOCSIS 3.1 infrastructure to deliver up to 8 Gbps downstream performance. For SPs operating on a longer upgrade cycle to DOCSIS 4.0, this option provides an economical steppingstone to DOCSIS 4.0-like speeds from updated modems.

RF is in the spotlight again

HFC networks see a lot of attention paid to the fiber portion, simply because extending SP services further out into the network depends on high-performance fiber. National infrastructure projects devoted to pushing fiber into underserved and rural communities has also been a primary driver of network growth over the last few years.

But to enable DOCSIS 4.0 bands and deliver 10G network speeds, SPs are once again focusing more attention on the RF side of the network, thanks primarily to new amplifiers that can support the 1.8 GHz DOCSIS 4.0 spectrum. These amplifiers are essential to extend the reach of the coaxial network further from fiber nodes without degrading network performance. Here also, SPs are finding an unusually rich range of options available, as a number of smaller and newer manufacturers offer 10G-capable amplifiers. In a highly commoditized and competitive market, SPs must leverage every economy available to them, and a broader range of solutions providers can only serve to drive down costs. While Tier 1 SPs are able to leverage favorable terms by scale, smaller SPs will continue to take advantage of the benefits afforded by multiple DOCSIS 4.0 technologies, as well as multiple fiber and RF solutions providers.

HFC networks vs. fixed wireless access

SPs are not merely in competition with each other; in recent years, fixed wireless access (FWA) has emerged as a lucrative business for 5G and 4G cellular networks. Using surplus spectrum to carry broadband traffic, mobile network operators (MNOs) are able to broaden established customer relationships and preserve loyalty by bundling cellular and broadband services over their airwaves. In some markets, FWA has emerged as a strong competitor in the race to connect rural communities where cable and fiber are not yet fully established.

Like DOCSIS networks, FWA can deliver high speed connectivity and-where 5G is used-extremely low latency, important for supporting many networked activities from streaming video to competitive gaming. Connected via an on-premises base station and integrated Wi-Fi®, FWA networks are potentially able to reach a large number of consumer and commercial subscribers. Even so, FWA positions itself as a complement to, rather than a replacement for, HFC networks. This is because of HFC networks' main advantage-one that will only expand with the ongoing rollouts of various flavors of DOCSIS 4.0-which is in the width of the pipe. FWA's upstream and downstream are limited based on the bands available to the specific deployment, and performance can vary based on other network demands being managed from minute to minute.

Unified DOCSIS 4.0's symmetrical upstream and downstream speeds are simply in an entirely different category than those possible with FWA at this time. While FWA does enjoy a pricing advantage for the customer in most cases, that advantage is limited by its current 100 Mbps speeds and is likely to erode as time goes on due to the upgradable nature of fiber networks. To add spectrum to a cell site generally requires the addition or replacement of antennas, radios, connectors and cabling, while DOCSIS 4.0 networks can often add spectrum via a split upgrade, or via virtual cable modem termination system (CMTS) or distributed access architecture (DAA) operation.

Many roads, one destination: Unified DOCSIS 4.0

In 2025, SPs will chart different paths forward. Some will bridge to DOCSIS 4.0 downstream performance via DOCSIS 3.1E, others will deploy ESD and FDx infrastructure according to their specific network needs. They will also have an expanded universe of solutions providers to work with. However those first steps are taken, the only real destination in the short to medium term is unified DOCSIS 4.0, incorporating both ESD and FDx technologies into a truly game-changing HFC network.

##