More than 60% of residential broadband subscribers in the US received their services via cable modems by the end of the third quarter of 2018, according to Ovum research. With increased FTTH competition across the country, cable operators continue to upgrade their bandwidth speed tiers, as well as enhance their service offerings. Several cable operators have even announced plans to take an FTTH approach to compete. Yet most cable operators continue to use their existing hybrid fiber-coaxial (HFC) infrastructure to deliver higher speeds, and even gigabit services.
But, in order to remain competitive with growing FTTH offerings, cable operators must go beyond platform upgrades like DOCSIS 3.1. To future-proof their networks, cablecos need to look to a distributed access architecture (DAA) -- a collection of technologies -- accompanied by a "fiber-deep" framework to transform their headends/hubs and outside plant. While there are philosophical debates over the best technical approach, the objective is to produce more bandwidth per subscriber while realizing reduced opex.
DAA is a key transformation in next-generation cable-access networks. The shift to placing the intelligence in the field is a relatively new concept in cable access -- HFC networks were designed like bookends, with key functions at either end, in the headend/hub and at the customer premises. As intelligence is pushed out of the headend and into the outside plant, more efficiencies are realized: lower real estate, power and cooling costs. Further, DAA can be adopted in stages while ensuring that the customer premises side remains the same, thereby avoiding expensive upgrade costs to subscriber homes.
As functions are moved out of the headend/hub and into the field, outside plant equipment and operations will increase, leading to more complex routine testing and maintenance programs, all of which need to be assessed in the planning stage. This is where SDN/NFV plays a key role in DAA, not just to keep opex lower but also to automate, monitor and control quality of service. A larger outside plant is not without risks: the potential for theft, as well as the potential damage from humans, animals or environmental factors/disasters, increase with more intelligence in the field.
Considerations for DAA upgrade paths vary from operator to operator and within each operator's network. They include current space constraints in the headend/hub, rising power/cooling/real estate costs, the availability of capex for network investment, current network capacity and future growth plans/onboarding new service groups.
It's hard to talk about DAA without bringing up "fiber deep," a term that has become enshrined in the discussions about next-gen cable networks. Fundamentally, fiber deep is the act of pulling fiber in the network closer to the end user. In a fiber-deep scenario, amplifiers between the headend and the end user are reduced, with the eventual goal of elimination. In a perfect scenario, the only active device left in this portion of the network is the fiber node, connected to the headend via digital optics, sometimes referred to as Node+0.
Pulling fiber closer to a customer while still utilizing existing HFC network infrastructure enables cable operators to support new services and increased bandwidth for both residential and business customers. One example of cable operators pulling fiber all the way is 10G-EPON, accompanied by DOCSIS provisioning over EPON (DPoE). DPoE utilizes digital optics from the headend to support a remote OLT out in the field without any major upgrades to the headend.
The introduction of digital optics and a fiber-deep approach enable the aforementioned capabilities of SDN and NFV, allowing easier provisioning and scaling, as well as orchestration and automation features to manage the newly decentralized networks.
Several traditional CMTS/CCAP vendors have introduced DAA solutions. Arris and Cisco, consistently the two cable-market leaders in CMTS/CCAP equipment shipments and revenues, have both introduced Remote PHY devices and shelves. Recently, Cisco announced the introduction of its Cloud-Native Broadband Router to enable virtualized CCAP and is placing increased emphasis on analytics, automation and optimization.
But both vendors must continue to innovate, given the growing competition in the DAA space. Casa Systems has garnered decent market share and has developed a vCCAP. Several other equipment vendors have moved into the cable access equipment market because of the DAA opportunity, including Harmonic, Huawei and Nokia (through its acquisition of Gainspeed).
The transformation of cable-access networks from analog to digital optics is also attracting vendors from outside the CMTS/CCAP vendor market, with fiber-deep products and solutions. Capitalizing on their strengths as optical-transport vendors, Ciena and Infinera have been aggressively promoting their product portfolios to cable operators. Nokia, Adtran and Calix all have portfolios of 10G EPON and accompanying software platforms to support cablecos.
The goal for any operator is to pull fiber closer to the end user. Eventually, all broadband access networks will be full fiber, but there is a long way to go before that happens. Cable operators will transform their networks and service offerings, just as they always have, to stay competitive with their telco rivals.
Further iterations of DOCSIS will enable symmetrical, multi-gigabit services for customers. But ultimately next-gen technology paired with DAA is what will make the future business case work for cable.
— Jaimie Lenderman, Senior Analyst, Ovum