RF over Glass (RFoG) Solutions: Bridge HFC to All-Optical Networks
RF over Glass (RFoG) is a complex deep-fiber network that uses Passive Optical Network (PON) technology to take the place of coaxial trunks in traditional HFC networks. Premlink offers SCTE-compliant RFoG solutions designed for higher bandwidth, carrier-grade reliability, and easy migration. Our technology allows operators keep existing DOCSIS services while moving to full-fiber future.
What is RF over Glass (RFoG)？
Core Architecture & Wavelength Plan of RFoG
In telecommunications, radio frequency over glass is a deep-fiber network design in which the coax portion of the hybrid fiber coax (HFC) network is replaced by a single-fiber passive optical network (PON). Downstream and return-path transmission use different wavelengths to share the same fiber (typically 1550nm downstream, and 1310 nm or 1590/1610nm upstream).
Return-Path Standard & Coexistence with xPON
The return-path wavelength standard is expected to be 1610 nm, but early deployments have used 1590nm, somewhere CWDM wavelength ( e.g, 1510, 1530, 1570…) in us. Using 1590/1610nm for the return path allows the fiber infrastructure to support both RFoG and a standards-based PON simultaneously, operating with 1490 nm downstream and 1310 nm return-path wavelengths. The RFoG system ends at the subscriber side interface of an RFoG Optical Network Unit (R-ONU) at the home.
The Technology Background & SCTE Standardization
Origins and Initial Development of RFoG Technology
RFoG technology is an HFC access network solution based on a cable TV fiber optic network with RF transmission as the primary business. In 2007, the US company called Alloptic (all-optical network) was the first to develop RFoG technology and related products, and it promoted this technical solution to several cable TV operators in North America.
Standardization and Early Adoption by SCTE
So currently, a lot countries throughout the world have adopted this technology. In 2007, the Society of Cable Television Engineers (SCTE) accepted RFoG’s standard development plan.
The Interface Practice Subcommittee of SCTE began developing a series of interface standards in March 2008, enabling the newly added passive FTTH network to interconnect with existing HFC networks and front-end devices, and ensuring that traditional digital TV set-top boxes and DOCSIS compliant modems are compatible with passive FTTH networks. Users just need to install an optoelectronic converter at home to view high-definition TV, while also enabling value-added services such as VOD video playback and broadband internet access.
Release of the RFoG Standard
In 2010, the SCTE organization formally released the RFOG FTTH technical definition, “ANSI/SCTE174-2010 Radio Frequency over Glass Fiber to the Home Specification”.
Advanced RFoG Architectures
Distance vs. Split Ratio Flexibility
Customers located beyond of the 20 km radius can also be served by lowering the split ratio (up to 48 km). Alternatively, if the distance is reduced, the split ratio can be raised.
RFoG (RF over Glass) regularly gets deployed with two architecture types:
Passive RFoG Architecture
Passive: 32 split over 20 km that comply with the requirements for PON; no active devices in the facility.
Hybrid RFoG Architecture
RFoG (RF over Glass) regularly gets deployed with two architecture types:
Passive: 32 split over 20 km that comply with the requirements for PON; no active devices in the facility.
Hybrid: active field optics (EDFA, return Rx/Tx) are used to conserve or expand the reach of the fiber.
Customers located beyond of the 20 km radius can also be served by lowering the split ratio (up to 48 km). Alternatively, if the distance is reduced, the split ratio can be raised.
Premlink Specialized Advantage:
Premlink’s RFoG solutions are engineered for high reliability and full compliance with SCTE-174 standards. Our PL10/PL20 series RFoG ONUs feature high-sensitivity receivers and precision burst-mode transmitters to ensure stable return-path performance across diverse fiber distances. By offering integrated WDM filters for XGSPON/GPON pass-through, Premlink enables MSOs to overlay 10G data services alongside traditional RF video. Our hardware is optimized for low-noise 1550nm downstream and supports flexible return-path wavelengths (1610nm, 1590nm, 1570nm, other CWDM wavelengths), providing a cost-effective migration path from HFC to all-optical FTTx network.
What is RFoG Combined with xPON ?
The RFoG (RF over Glass) combined xPON (GPON or XGSPON & GPON co-exsitence) can be deployed as an extension of the installed HFC network. Cable operators can also adopt a GPON or XGSPON design that includes the RFoG return path, allowing them to continue to use existing premises equipment.
Downstream Signal Path: From OLT to Customer Premises
Downstream GPON/XGSPON & GPON co-exsitence traffic travels from operator’s data network to an OLT, which routes it to a WDM device with 1310nm and 1490nm or 1277nm and 1570nm wavelengths. The CMTS converts DOCSIS and video communication to optical traffic, which is then sent to a WDM platform via an EDFA amplifier ( The EDFA combined WDM device into one unit called EDFA PON Combiner) for longer distances. The WDM device distributes traffic through a splitter to a mini node at the customer’s premises. The mini node then transfers video, voice, and data traffic over coax.
Upstream Signal Path: Return Traffic to Headend
All return path traffic is converted to optical by the mini node and sent over a 1590 nm or 1610nm (CWDM) wavelength to the headend, where an optical receiver converts it and sends it through a CMTS for access to voice, data, and video network resources. This solution allows cable operators to implement a “mixed system” supporting both GPON/XGSPON & GPON co-exsitence and DOCSIS services.
Coexistence Deployment and Migration Strategy
Cable providers can operate RFoG and GPON/XGSPON & GPON co-exsitence solutions in the same area with advanced design considerations, allowing for neighbors to receive services from both. A WDM platform separates RFoG and GPON/XGSPON & GPON co-exsitence, and cable operators can gradually transition subscribers to a GPON/XGSPON solution based on market demands.
Implementation: RFoG Mini Node with xPON Expansion
Initially, the cable operator would set up an RFoG mini node with a xPON optical expansion connection. The xPON-specific wavelengths, 1490 and 1310 nm or 1277 and 1570nm, are routed to the expansion port. If a cable operator needs to provide more Ultra-Broadband services to a specific residence, such as higher-speed symmetrical data service or IPTV, a GPON/XGSPON ONT can be connected to the expansion port. The RFoG small node can continue to provide standard video services and manage legacy return signals as needed.
What is the Standard for RFoG Technology?
The Society of Cable Telecommunications Engineers (SCTE) has a set of rules and standards that define and govern RFoG technology. These standards make sure that different systems can work together, perform well, and connect easily to existing HFC networks. The ANSI/SCTE 174 series is the most important specification. It has the following major releases:
ANSI/SCTE 174-2010: The first standard that clearly defined the RF over Glass Fiber-to-the-Home specification.
ANSI/SCTE 174-2018: A major update that includes new technology and lessons learned from the field.
SCTE 174 2018 (R2024) ：This is the most recent version that has been reaffirmed, showing that the standard is still valid and useful.
RFoG Network Application
RF over Glass (RFoG) is used in important situations like moving deep-fiber networks to HFC, building new FTTH networks that need RF video support, and providing access to high-density MDUs. This architecture gives cable companies a smooth and affordable way to upgrade their infrastructure while using their current customer equipment and moving toward a full-fiber future.
Frequently Asked Questions About RF over Glass
RF over Glass (RFoG) is a technology that uses fiber optics instead of coaxial cables in traditional TV networks. It sends TV, internet, and phone services through a Passive Optical Network (PON). It's like upgrading the road from copper wires to fiber highways. It's faster, more reliable, and ready for the future. Its main benefit is allowing cable operators to deploy fiber networks while continuing to use existing DOCSIS cable modems, set-top boxes, and headend CMTS equipment.
es. Using the SCTE-174 standard wavelength plan, like the 1610nm return path, RFoG can work at the same time as GPON (1490nm/1310nm) and XGSPON (1577nm/1270nm) with a WDM combiner, like Premlink's PON EDFA Combiner.
Our RFoG ONUs have high-performance burst-mode transmitters that only turn on when they get a return signal. When used with precise wavelength management (1610nm/1590nm), this cuts down on noise and makes sure that communication between the subscriber's home and the headend CMTS is always reliable.
Passive RFoG doesn't use any active devices between the headend and the subscriber, which is usually up to 20 km. Hybrid RFoG uses active optics like EDFAs and return-path receivers to make the signal reach farther (up to 48 km) or to split it more for high-density MDUs.
This is a special device, like the Premlink PL10-3A or PL10-6A, that receives RF video at 1550nm and has a WDM pass-through port just for that. This lets you connect a GPON or XGSPON ONT later without having to change the wiring in the house.
