In an ever-changing broadband world, cable operators are inaugurating a new era of connectivity with DOCSIS 4.0’s multi-gig symmetrical speeds and much-improved network performance. This isn’t just incremental. Amidst rising competition from fiber and wireless competitors, DOCSIS 4.0 is a new paradigm that will help operators retain and win customers demanding high-speed, low-latency services.
The DOCSIS 4.0 Journey: ESD and FDX
DOCSIS 4.0 gives multiple system operators (MSOs) two primary paths to the 10 Gbps (G) goal: Extended Spectrum DOCSIS (ESD) and Full Duplex (FDX) DOCSIS, each designed to maximize both upstream and downstream capacity.
The preferred approach of Charter Communications, ESD increases the network’s entire frequency range to 1.8 GHz and, potentially, up to 3 GHz in the future. Upstream frequencies go up to an ultra-high split at 684 MHz. Downstream/upstream throughputs can reach 10G/6G. ESD is ideal for operators with a large legacy infrastructure as it builds on traditional cable technologies and extends network life with manageable upgrades.
FDX DOCSIS, on the other hand, allows for symmetrical speeds by having concurrent upstream and downstream transmissions in the same frequency range. Tapping spectrum up to 1.2 GHz, FDX has potential throughputs similar to ESD. While technically challenging, FDX is ideal for dense areas where symmetrical speed is key, particularly for services that require real-time interactivity. Comcast is the leading champion of FDX.
Both ESD and FDX are big steps up from DOCSIS 3.1, going beyond the 10:1 downstream-to-upstream ratio and giving operators more flexibility in serving urban, suburban and rural markets.
What DOCSIS 4.0 Changes on the Road to 10G
Upgrading to DOCSIS 4.0 isn’t without its challenges. It requires a top-to-bottom review of existing infrastructure and significant changes to accommodate the new technology’s requirements.
For MSOs deploying DOCSIS 4.0, migration to Distributed Access Architecture (DAA) – commonly realized through a virtual CMTS and remote PHY nodes – is a pre-requisite for FDX and ESD. Both may require additional upgrades of CMTS hardware or firmware, fiber optic nodes, and (especially for ESD) amplifiers. When spectrum of up to 1.8 GHz or higher is involved, operators also need to deploy passive network elements (taps and splitters) that can handle the higher frequencies.
Beyond the network upgrades, operators need a few operational tweaks. Those include updated management software and monitoring systems, updated tools for spectrum management and troubleshooting, and relevant training for network operations teams. Subscribers also need DOCSIS 4.0 modems.
What’s the cost of this road to 10G? One early estimate in 2022 from Comcast for an FDX network upgrade was less than $200 per home passed (HP). More recent comments from operators indicate higher costs for FDX and ESD, though still less than the $1,000-$2,000/HP for fiber to the home (FTTH). The final bill for DOCSIS 4.0 will depend on the current state of one’s network, the specific upgrade path and related requirements.
What DOCSIS 4.0 Means for the Network
While the costs vary, DOCSIS 4.0 brings a number of definite benefits that will shape the cable network’s 10G future:
- Symmetrical High-Speed Access
The ability to deliver multi-gig symmetrical broadband strengthens the industry’s core service. It overcomes the traditional asymmetric disadvantage and gives cable operators an option other than PON for customers who want both fast downstream and extra high-speed upstream. - Lower Latency
Improved queue management and scheduling, better traffic prioritization and other techniques, along with more spectrum in ESD and lower switching time in FDX bring latency down to levels acceptable to applications demanding that data travel nearly instantaneously from source to destination. - Better Security
New encryption and security features in DOCSIS 4.0 – support for multiple versions of the Baseline Privacy Interface (BPI) protocol, advanced authentication between devices and the network, and more – give cable operators and their customers more peace of mind in a connected world. - Competitive Advantage
Fiber-like speeds over HFC gives MSOs a big advantage, especially in areas where fiber is too expensive to deploy. DOCSIS 4.0 allows them to compete with fiber overbuilders without having to build entirely new infrastructure.
Flexibly Scaling to 10G and Beyond
Both ESD and FDX are big steps forward, but industry leaders have already blazed some trails. Moreover, migrations can be more flexibly managed today. New technologies such as direction-neutral amplifiers, pluggable diplexers and other hardware and software allow operators to upgrade their network in phases, minimizing upfront investment and allowing them to add capacity as subscriber demand grows.
Meanwhile, even as DOCSIS 4.0 begins rolling out, major players are anticipating the need for greater capacity. To the extent that operators pull fiber deeper by reducing amplifier cascades, which is one possible outcome in FDX, they further reduce the cost of strategic transitions to all-fiber solutions. That includes the possibility of deploying 25G PON, already available from several suppliers.
On the other hand, as revealed at TechExpo in Atlanta, Comcast, Charter Communications and Broadcom are looking to deliver 25G over the HFC plant by leveraging 3GHz of spectrum and silicon, reportedly already developed, that supports both FDX and ESD. This plan could become the basis of DOCSIS 5.0.
Safe Bet for the Future
DOCSIS 4.0 is a big deal for the cable network. Not every consumer or business is looking for the high-speed, symmetrical broadband it can deliver, but there is enough interest to matter. Moreover, competition over “billboard” speeds is real, with some ISPs already advertising 10G services or higher. Finally, never in the history of high-speed data has it been a smart move to bet against continued growth in bandwidth-intensive applications.
By planning ahead and investing in the infrastructure for DOCSIS 4.0, operators are not just meeting current needs; they are also future readying for the long term. For those with that mindset, DOCSIS 4.0 is not just an upgrade, it’s an investment in 10G – and beyond.
To learn more about DOCSIS 4.0, see our eBook.