RF over Glass

In telecommunications, radio frequency over glass (RFoG) 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 1,550 nm downstream, and 1,310 nm or 1,590/1,610 nm upstream). The return-path wavelength standard is expected to be 1,610 nm, but early deployments have used 1,590 nm. Using 1,590/1,610 nm for the return path allows the fiber infrastructure to support both RFoG and a standards-based PON simultaneously, operating with 1,490 nm downstream and 1,310 nm return-path wavelengths.

RFoG delivers the same services as an RF/DOCSIS/HFC network, with the added benefit of improved noise performance and increased usable RF spectrum in both the downstream and return-path directions. Both RFoG and HFC systems can concurrently operate out of the same headend/hub, making RFoG a good solution for node-splitting and capacity increases on an existing network.

RFoG allows service providers to continue to leverage traditional HFC equipment and back-office applications with the new FTTP deployments. Cable operators can continue to rely on the existing provision and billing systems, Cable modem termination system (CMTS) platforms, headend equipment, set-top boxes, conditional access technology and cable modems while gaining benefits inherent with RFoG and FTTx.

(From Wikipedia)