Now that the telecommunication industry is increasingly adopting Distributed Access Architecture (DAA) technology to move key functions and equipment from the cable facility to the access network, one particular instantiation of DAA, the Distributed CCAP Architecture (DCA), specifically addresses the HFC network and DOCSIS technology. The burning question is whether or not this new solution is having a positive impact for cable operators. Let’s take a look at telecommunication’s growing DCA deployments and the operator benefits of DCA.
Why DCA?
Operators are evolving their access network architectures to keep pace with the demand from residential, commercial, and mobile customers. Following years of technology development and trials, the shift to DCA is expanding the network's capacity to deliver new, more advanced services and operate more efficiently and effectively.
DCA will enable increases in the amount of traffic on a telecommunication network. There are a couple of DCA solutions available to operators for delivering services to consumers over a coaxial medium. Now, thanks to CableLabs' new Flexible MAC Architecture (FMA) specifications, industry technologists can freely choose among Remote PHY (R-PHY) and Remote MACPHY (R-MACPHY) variants to meet their customers’ needs today and in the future.
These two solutions move the physical layer (aka PHY layer), as well as the media access control (MAC) in the case of Remote MACPHY, out of the facility and into the fiber access node. There is also an option to separate the layers within the facility to provide digital connectivity called Remote PHY shelf. With the PHY layer (or MAC and PHY layers) moved into the node, fiber connections transition from analog optics technology to digital optics technology, thereby leveraging the ubiquity of optical IP/Ethernet transport between the facility and the optical node. Since the PHY layer is closer to the premises, operators can leverage the lower signal-to-noise ratio (SNR) to provide higher modulation efficiency, more capacity, and overall faster service tiers and improved network performance.
Among the benefits for operators, significant rack units (RUs) are freed up in the facilities, decreasing space, power, and HVAC costs. Additionally, operational expenses (opex) associated with alignment and maintenance are reduced, while network visibility is improved due to the remote device intelligence.
SCTE Generic Access Platform (GAP)
Historically, large network operators may have managed a supply chain of over 40 different node enclosures and their related internal electronics in their network. Operators need to procure the components, keep sufficient quantities in their warehouses and trucks, and educate technicians to work with all these variants. Historically, none of these enclosures, transmitters, receivers, amplifiers, and power supplies are interchangeable. Standardizing the node enclosure eliminates this logistical supply chain pain point and allows equipment vendors to focus on innovating and developing specific modules within the enclosure. In addition to providing operational efficiency by standardizing the node enclosure, GAP will also support mobility by including LTE and 5G wireless modules.
SCTE has released two GAP standards. SCTE 273-1 outlines the specifications for the GAP enclosure, while SCTE 273-2 details the requirements for interchangeable modules within that GAP enclosure. Use cases envisioned for GAP include cable access, fiber access, wireless access, multiaccess edge computing (MEC), and future applications.
Improved digital optics of DCA
DCA enables operators to leverage the efficiency and capacity of digital optics in the access network. Operators are now separating the layers of the telecommunication network within the facility or moving the layers into the access network. As mentioned, in DCA, operators can relocate PHY layer and MAC layer components within the access network, pushing the edge closer to the premises; R-PHY relocates the PHY layer of the CCAP while R-MACPHY relocates both the MAC and PHY layers of the CCAP. But DCA has additional benefits, as it uses dense multiplexed digital fiber and a roadmap to virtualize the layers of the network.
DCA networks may provide 10G connections over a digital multiplexed fiber or potentially, in the near future, via a coherent digital fiber link.
CableLabs' specifications related to DCA define the interface specifications required for the deployment of a scalable and cost-effective distributed hybrid fiber/coax (HFC) access network. The architecture enables operators to take full advantage of the gigabit capabilities of DOCSIS 3.1 technology as well as support the developing DOCSIS 4.0 technology. This upgrade pathway will provide enough peak capacity to support customer demand far into the future.
Automation
DCA is compatible to the increased automation sought by telecommunication operators to meet the needs of the aggressive business services market. Essentially a programmable and application program interface (API)-driven network architecture, DCA diverts from more rigidly engineered solutions. For a programmable network, a software-based automation engine is may be a logical next step.
DCA also aligns with cloud computing, where functions can be virtualized and distributed, and its framework also aligns with mobile edge computing (MEC), bringing low-latency processing closer to the customer. As a modular technology that does not require an entire process and infrastructure for automating a single service, DAA enables automation that can be repeatable and adaptable for a wide variety of processes and services.
For automation to be effective, it needs to adapt to evolving software requirements and coordinate activity in all directions and with multiple vendors.
Is your network ready for the DCA transformation? Since DCA enables the evolution of telecommunication networks by decentralizing and virtualizing facility and network functions, the need for ongoing DCA deployment to address consumer demand is no longer in question.
Deployment strategies may differ substantially, but DCA replaces analog fiber with Ethernet/IP connections (digital fiber) and creates a software-defined network (SDN) that supports:
- Node evolution with R-PHY and R-MACPHY
- Transition to digital optics, removing analog lasers
- Digital fiber closer to the premises
- Migration to centralized data centers
- Flexible advertising, channel lineups, and bandwidth management.
- Improvements to both cost and capacity are driving factors to deploy DCA, including:
- Increased HFC fidelity
- Greater facility density.
Future benefits for cable operators who upgrade networks with DCA include low-latency functionality for gaming and 5G backhaul, better performance to optimize the DOCSIS network for more capacity and speed, and software features for operational simplicity and support.
Dig Into DAA
The Distributed Access Architecture (DAA) Essentials online course available from SCTE covers the evolution of the HFC access network to accommodate higher bandwidth. The course provides the essential knowledge for learners in R-PHY and R-MACPHY architectures along with new service offerings like PON and wireless. Upgrades at the optical node and modifications in the facility are examined throughout the course.
Steven H. Harris is executive director, education and technical sales, L&D for SCTE® a subsidiary of CableLabs®.