Bridging the gap between copper-based and fiber-based gigabit service deployments

Bridging the gap between copper-based and fiber-based gigabit service deployments

By Herman Verbueken, Director of Broadband Forum’s Physical Layer Transmission Work Area

The deployment of fiber deeper and deeper into broadband networks is restricted by cost and logistical issues, rather than the technology itself. Installing fiber to every household can involve significant labor costs, be disruptive to customers and can often be delayed due to the lengthy process of approvals from building owners or local authorities.

To reduce expense and complexity of deploying fiber networks, industry players are considering options of leveraging existing copper infrastructure and reusing existing network operators’ assets, while still providing Fiber to the home (FTTH)-like broadband connectivity. This can be achieved by extending the fiber network with copper-based infrastructure to provide multi-gigabit access into the home/ business. Such architecture is called the Fiber to the extension point (FTTep).

FTTep vs FTTdp

The main objective of the FTTep is to extend fiber-based gigabit services by re-using existing copper infrastructure, which can be Point-to-Point (P2P) or Point-to-Multipoint (P2MP). In many areas, the cost and complexity of deploying this architecture may be lower than for the fiber-only FTTH architecture, thus providing a simpler, faster and more economic deployment.

Over the last few years, FTTdp or Fiber to the distribution point garnered a lot of attention among providers as a possibility for offering high-speed services especially for users who are directly connected to the CO/exchange and are unable to get Fiber to the cabinet (FTTC)/VDSL2. Or users who are in an FTTC deployment area, but their cabinet is too small to commercially justify a full digital subscriber line access multiplexer (DSLAM), or who are within an Multi Dwelling Unit (MDU).

FTTdp using G.fast, as described in TR-301, is considered a subset of FTTep. Both provide gigabit services to the end user. The difference is that in the case of FTTdp, the equipment is managed as two separate networks: the part up to the distribution point (dp) as a fiber network, the dp and parts after as a copper network, often managed by different service teams with each sometimes having their own objectives.  By integrating both networks into one, the FTTep architecture enables the seamless management of one single fiber network, simplifying the rollout of gigabit services.

MR-419 and TR-419

The Broadband Forum’s Physical Layer Transmission (PHYtx) Work Area has published two reports about FTTep. MR-419 “Utilizing Existing Copper Infrastructure for Deployment of Fiber-grade Services” provides the reader a top-level insight to the benefits and reasons why Fiber to the extension point is a viable architecture to deploy fiber services cost-effectively. The document references some FTTep use case scenarios that are described in Broadband Forum’s Technical Report TR-419.

TR-419 “Fiber Access Extension over Existing Copper Infrastructure” describes different ways of providing fiber-based access to customers by employing existing copper infrastructure without causing significant degradation in Quality of Experience (QoE) compared to the FTTH. This Technical Report describes several use cases for operators choosing to implement a FTTep solution. The focus is on the following aspects of the FTTep solution:

Architectural aspects:

• Support of PON fiber access extension over P2P and P2MP topologies
• Definition of interfaces (northbound and southbound) and functionalities to be implemented to comply with the requirements of the use cases.

Management aspects:

• Definition of the management infrastructure focused on Netconf/ YANG.

Operational aspects:

• Security, powering and maintenance, and parametrization of the FTTep solution to best fit the use case.

TR-419 defines the overall architecture of a FTTep network and describes the main location features and principals as well as various deployment and migration options. Key points from the large number of use cases brought forward by different operators and vendors, describing the detailed functional requirements, are also provided. In the appendixes, this Technical Report provides implementation guidelines for FTTep deployments with a focus on technology specific aspects of using different underlying technologies such as Multimedia over Coax Alliance (MoCA) Access, ITU-T G.fast and ITU-T G.hn Access.

What’s next?

FTTep provides additional ways to address the barriers to broadband access in some brownfield PON deployments by reusing the existing infrastructure for multi-gigabit services. A next issue of TR-419 should further refine the FTTep architecture and also address representative use cases from the Broadband Forum Wireless-Wireline Convergence (WWC) Work Area on 5G Fixed Mobile Convergence (FMC) and Fixed Wireless Access (FWA), and wholesale. It should also address technology specific aspects of PON fiber access extension over P2MP topologies and add details on FFTep using other copper technologies, such as ITU-T G.mgfast.

Interested to contribute to the future work and direction of FTTep? Do you want to gain further insight into what the Physical Layer Transmission (PHYtx) Work Area is doing? Visit: https://wiki.broadband-forum.org/display/BBF/Physical+Layer+Transmission.

Read the Broadband Forum’s latest release on TR-419 detailing how fiber-based access can be provided to customers by utilizing existing copper infrastructure as opposed to the installation of fiber to end-users’ premises, which may not be economically or physically viable.