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HFC to FTTx - How Far Can Fiber Go?

You know why fiber needs to be closer to subscribers. ARRIS experts can help you decide how, when, and where

Service Providers have multiple architectural approaches to evolve their access networks, migrating Hybrid Fiber Coax (HFC) networks to extend fiber deeper into the network. Deploying multiple architectures, at different times, in a single network is common.

They need the ability to support multiple paths, without constantly investing in new platforms, as they move towards enabling 100s of Gigabits of IP bandwidth for video and broadband services.

With our access network evolution framework, ARRIS can help create a flexible migration plan that meets current and future network requirements, while extending the value of investments in existing HFC networks.

Why are networks evolving?

  • Bandwidth requirements
    Based upon current projections of bandwidth required to deliver video (QAM, SDV and IP) and data services, Service Providers will reach full capacity on their networks in about 10 to 12 years. Some may see it sooner in specific areas of their network. Demand for bandwidth in the access network infrastructure continues to grow, driven by 'billboard speeds' and data consumption.
  • Network complexity
    Service Providers are looking to simplify their network infrastructure for all services including high speed data, voice, program channels, Video on Demand (VOD) and new services. They have the opportunity to reduce network complexity and operating expenditure and are able to adopt lower cost systems used by web based video services for common video distribution.
  • Network reliability
    These changes enable improved network reliability and Quality of Service (QoS).

Fiber Deep - Bandwidth trends
60 Years of Bandwidth Trends (Modified Nielsen)

Decision drivers for Service Providers

  • Headend capacity
    Space, power, or other facility constraints may prevent the addition of further headend equipment. Network evolution solutions include the ability to increase density in the headend while using power more efficiently, or distributing capabilities at the headend to the outside plant.
  • Economics
    Capital and operating costs, as well as the need to continue leveraging existing investments, are always important considerations for Service Providers with network evolution implications for inside plant, outside plant and CPE.
  • Residential greenfield
    Installing fiber for new home construction costs less than replacing coaxial cable with fiber later. For multi dwelling units, where fiber passes a high density of subscribers, PON may be more efficient than other approaches.
  • Environment
    Real estate costs, zoning regulations, power distribution, plant configuration, and other factors may dictate different allocations of indoor vs outdoor equipment.
  • Timing and availability
    The feasibility of some network evolution paths depend on when products are available in the market, when specifications are finalized, and other factors outside the control of Service Providers.

Architectural approaches for migrating HFC networks to FTTx

  • Fiber to the Home (FTTH) with analog modulation
    Radio Frequency over Glass (RFoG) is an analog optics technology that provides a logical migration path to Passive Optical Network (PON) architectures. By replacing the coax portion of an HFC network with a single-optical fiber and extending the analog QAM signals to home to an RFoG-ONU, operators can continue to use existing back-office infrastructure.
  • Fiber to the Node with digital modulation
    A cost-effective migration strategy toward FTTx that moves the fiber closer to each subscriber’s home, often called Distributed Access Architecture (DAA). DAA reduces the number of active devices, replaces analog optics from the headend to the Node and creates additional space in the headend.
  • Fiber to the Home (FTTH) with digital modulation
    For links up to 20 km, or 60 km with extender,  PON offers a cost effective, low maintenance approach for adding higher data rates for video and other Internet services, without having to deploy individual fiber to each subscriber.

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Radio Frequency over Glass (RFoG) is an analog optics technology that provides a migration path to FTTx or xPON architectures by replacing the coax portion of a HFC network with a single-fiber passive optical network to increase capacity, while continuing to use existing back-office infrastructure. RFoG eliminates RF actives (amplifiers and line extenders) from the network, reducing failures, maintenance, and power requirements.

An RFoG network is capable of seamlessly delivering functionality and services to subscribers in a manner that is comparable to current HFC systems. RFoG provides an FTTH PON like architecture for Service Providers without having to select or deploy a PON technology.

An ARRIS RFoG network provides distinct performance advantages over current HFC networks

  • Expand upstream and downstream bandwidth and significantly extend network reach by eliminating the RF noise and ingress inherent in coax deployments.
  • Significantly lower operating and maintenance costs by eliminating the need for HFC nodes and RF amplifiers.
  • Lower energy costs to provide a greener alternative to coaxial delivery, with the added benefit of less network downtime due to power outages.
  • Efficiently bridge between HFC and FTTx architectures and provides the infrastructure needed to transition to all-fiber, high-bandwidth 10G PON networks.
  • Immunity to environmental factors that can cause coaxial cabling to degrade physically over time.
  • A more economical choice for Multi-Dweller Unit (MDU) and rural deployments.
  • Multiple options to eliminate Optical Beat Interface (OBI) in the network.
  • Comparable to HFC performance in greenfield suburban residential deployments.

Fiber Deep - HFC to RFoG

Not all RFoG solutions are the same

ARRIS offers a wide range of innovative solutions that eliminate OBI in RFoG networks and supports the transition to DOCSIS 3.1 services:

  • AgileMax® Family of Fiber Distribution Devices
    By replacing the optical splitters found in traditional RFoG architectures, AgileMax's active optical distribution technology eliminates OBI from the network — even if it deploys multiple, active upstream lasers — achieving Service Groups of up to 1024 homes served on a single headend optical receiver port. AgileMax supports less-expensive 'non-tunable' R-ONUs and may be used with VHub technology to extend the reach of your network to over 20 km.
  • OBI-free R-ONUs
    ARRIS OBI-free R-ONUs allow Service Providers to select one of sixteen upstream wavelengths for each unit via an internal rotary switch, providing enough wavelength separation to avoid OBI. This wavelength management approach allows multiple OBI-free R-ONUs to transmit simultaneously into a single upstream optical receiver with no chance of OBI.

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Distributed Access Architecture (DAA) extends the digital portion of the headend to the node or PHY shelf), and places the digital to RF interface at the optical to coax boundary within the node (Remote PHY). Replacing the analog optics from the headend converts the fiber link to a digital fiber Ethernet link, increasing the available bandwidth improving fiber efficiencies (wavelengths and distance), and directional alignment with NFV/SDN/FTTx systems of the future.

DAA can be implemented gradually in concert with normal plant and service upgrades, at first leaving legacy services untouched, then gradually migrating RF functionality to the node.

Fiber Deep - Distributed Access Architecture

Advantages of a DAA approach

  • Network efficiency
    • Increased network capacity and simpler outside plant maintenance
    • Node evolution with Remote PHY, Remote MAC-PHY and Remote 10G EPON OLT
    • Better end-of-line signal quality, higher modulation rates, higher bit-rates
    • Better spectral efficiency, more wavelengths per fiber
  • Operational and capital expenditure benefits
    • Reduced head-end power, space and cooling requirements
    • Hub consolidation
    • Add QAMs without changing the RF combining network
    • Partitions scope of change on a node-by-node basis
    • Digital fiber “set and forget”
  • IP convergence
    • Extend IP network to the node
    • Alignment with FTTx build-out
    • Leverage standards-based interconnectivity and economies of scale

ARRIS DAA solutions

  • E6000® Converged Edge Router eCORE (Gen2) for data services – an upgradeable platform supporting HFC, DAA and PON
  • Flexible node platforms with the ability to support evolution from HFC, DAA and PON
  • Video Unified Edge (VUE) virtualized Video Core and video headend software which supports all DAA modes and IP or MPEG-2 Transport Stream backbones
  • ICX optical Ethernet switches for Remote OLT aggregation
  • Orchestration , Intelligence and Management services and application solutions for system deployment, automation and performance
  • Planning and Modelling consulting, and Network Evolution Services

Remote MAC-PHY is another distributed access architecture option, which moves the MAC (video and data) and PHY functionality to the remote node or shelf. Most signal processing and modulation occurs in the access network, not in the headend.

The ARRIS roadmap includes both Remote PHY and Remote MAC-PHY architectures as part of the access network evolution framework, which provides modular solutions for multiple network upgrade paths. This approach extends the value of HFC network investments, while enabling a seamless and profitable future transition to a completely IP network for all current and future services.

Both Remote PHY and Remote MAC-PHY have their advantages. Remote PHY is an excellent way to serve smaller hubs and sparsely loaded nodes with less headend equipment and fewer changes to provisioning and management infrastructure, while Remote MAC-PHY is better suited to pinpoint deployments or nodes with long fiber runs. An additional benefit of Remote PHY is that CableLabs® specification activities enable standards-based, multi-vendor system integration.

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For Service Providers where capacity or competition from other Fiber services is such that multi gigabit symmetrical (upstream and downstream) services are required, Fiber to the Home (FTTH) via an Ethernet Passive Optical Network (EPON) is the answer.

This enables Service Providers to:

  • Drive fiber into the last mile for commercial and residential customers using common network facilities
  • Increase revenue with high value commercial services customers
  • Maximize investment in DOCSIS® provisioning systems with DPoE provisioning solutions for PON gateway devices
  • Lower operational costs without the need for active outside plant
  • Offer symmetrical and multi Gigabit downstream services to residential customers

Primary deployment architectures for FTTH

  • Centralized
    The OLT (Optical Line Terminal) is housed in the headend or hub building, with all the services being distributed using digital signaling to ONUs (Optical Node Units) at each household. The distance limitation typical for EPON designs such as this of 20 km can be extended to as much as 80 km with active PON extenders in network based nodes or hubs.
  • Distributed
    Where the OLT is a Remote OLT (sometimes called Node PON or R-OLT) module housed in the node or cabinet location. The typical EPON distance limitation of 20kms still holds but from the node to home and not headend to home.
Fiber Deep - HFC to PON

For both approaches, the CableLabs® DOCSIS Provisioning of EPON (DPoE™) standards developed in conjunction with cable operators, enables integration with existing DOCSIS provisioning and monitoring systems. To the DOCSIS Operational Support System (OSS), an EPON OLT behaves like a CMTS, and an EPON ONU operates and provisions just like any other cable modem, leveraging long standing Service Provider investments in OSS and Business Support System (BSS) assets and processes

The ARRIS E6000 CER 10G EPON OLT platform uses the existing chassis to support Gen 2 RSM-2 module and EPFM (EPON Fiber Module) cards, supporting up to 16 10G –EPON optics modules per module, which replace D-CAM and U-CAM modules.

For typical greenfield networks, centralized EPON simplifies the deployment where Node OLT provides a migration strategy for Service Provider deployments in brownfield networks.

Summary Assessment of CAA and DAA DPoE System
Area10G EPON OLT with Standard WavelengthsRemote OLT (R-OLT)
Location of DPoE Subsystem Hardware Facility only 90% in the field
SDN Future Architecture Support Yes Yes
Plant Actives None  High 
Plant Space None High
Fiber Utilization 1 (Poor) 16
Serving Area Distance 10km - 20km No limit to node
20km to ONUs
Facility Consolidatation Limit to 20km No limit to node
20km to ONUs
Cost Per Customer 64 subs competitive vs. 128 PON Ext. Lowest cost with over subscription

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Solution Products

NC2000 Series Optical Nodes
NC2000 Series Optical Nodes
1.2 GHz 1x1, 1x2 and 2x2 Segmentable Nodes - Fiber Deep or HFC
NC4000 Series Optical Nodes
NC4000 Series Optical Nodes
1.2 GHz 4x4 Segmentable Nodes - Fiber Deep or HFC
OM6000 Opti Max Optical Nodes
OM6000 Opti Max Optical Nodes
1.2 GHz 4x4 Segmentable Nodes - Fiber Deep or HFC
AgileMax 1RU
AgileMax 1RU
Complete OBI Elimination RFoG Distribution Platform
E6000 Converged Edge Router
E6000 Converged Edge Router
Flexible, Upgradeable CCAP™ for Integrated, DAA, and 10G EPON Deployments
E6000n Remote PHY
E6000n Remote PHY
Distributed Access Modules for DOCSIS® and QAM video
ICX IP Switches for DAA
ICX IP Switches for DAA
Ethernet switches for Remote PHY and Remote OLT CIN