What is RFoG | RF over Glass basics | RFoG Architecture

This page describes RFoG (RF over Glass) basics and RFoG architecture. RFoG is the short form of RF over Glass Fiber.

The RFoG technology replaces coaxial part of HFC network by single mono-mode fibre. It is known as PON (Passive Optical Network). SCTE (Society of Cable Telecommunications Engineers) has published specifications for RF over glass fiber in the document ANSI/SCTE 174 2010. RFoG has advantages of transmitting RF over glass fiber due to its enormous bandwidth and less interference compare to radio frequency transmission. Moreover it travels distance of about 50 Km. This has become essential due to increasing demand of support for higher number of subscribers in a single cellular base station. This RFoG technology extends range of glass fiber based networks to the buildings and in the living rooms.

Following are the silent features of RFoG technology.
• Uses existing fiber optic network to couple RF (with AM/FM modulation).
• It uses 1550 nm for upstream transmission and 1310 nm or 1610 nm for downstream transmission.
• Provides downstream bandwidth upto 1 GHz.
• Enables FTTH and FTTB networks using DOCSIS standard.
• Seamlessly integrated into existing HFC network.
• RFoG transmitter and receiver modules provide distance coverage of about 50 Km.
Refer RF over fiber transmitter and receiver block diagram.

RFoG Architecture | RF over Glass Architecture

RFoG, RF over Glass

Figure-1 depicts RFoG architecture. As shown the architecture consists of optical Hub, ODN (Optical Distribution Network) and subscriber home premises. The main part in RFoG architecture is ONU (Optical Network Unit). The ONU is located between RF and optical domain. Depending upon AM or FM, RF modulation part will vary.

Like RF, optical system uses one wavelength for transmission (1550 nm) and the other wavelength for reception (1310 nm /1610 nm). Like diplexer is used to separate/combine transmit and receive bands in the RF, optical system uses WDM (Wavelength Division MUX/DEMUX) for optical signals. This is shown in the figure above.
Refer basic definitions of the Optical Components >>.

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