RF over Glass (RFoG) holds the promise of enabling Multiple System Operators (MSOs) to economically beef up their broadband fibre access capabilities. However, RFoG take-up has been somewhat constrained by Optical Beat Interference (OBI), the signal degradation phenomenon triggered by multiple optical transmitters communicating with closely spaced wavelengths at the same time over the same fibre.
Two new RFoG solutions claim to significantly alleviate the problem.
EMCORE Corporation has introduced a new RFoG Optical Networking Unit (ONU) transceiver that mitigates OBI with the use of the contractor’s Linear Externally Modulated Laser (L-EMLTM), and proprietary upstream laser wavelength management.
EMCORE’s RFoG ONU transceiver is designed to support standard CATV downstream and upstream transmission bands for triple-play voice, video and data signals in single family and multiple-dwelling unit applications. Downstream it receives a 1550 nm forward path optical signal carrying an RF cable television spectrum up to 1.2 GHz, making it compatible with the cable industry’s DOCSIS 3.1 standard. For the return path, it supports digital upstream transmission utilising an L-EML transmitter operating at 1610 nm that supports a 5 to 85 MHz spectrum. The ONU is compliant with the Society of Cable Telecommunications Engineers (SCTE) RF over Glass specification.
EMCORE President and CEO Jeffrey Rittichier reckons the product will significantly improve RFoG network performance in high-density customer environments by virtually eliminating the effects of OBI. “Units will begin to ship soon to select cable MSOs with production expected to ramp-up over the coming months,” says Rittichier.
Also on the OBI case is ADTRAN. That company’s RFoG OBI mitigation solution is designed to accelerate an MSO’s FTTH initiatives by supporting the reuse of existing CATV assets within both the headend and home. The ADTRAN OBI mitigation MicroNode does not require new centralised cabinet construction which, says the company, can often be delayed by right of way and power sourcing issues.
“By deploying our MicroNodes, ADTRAN cable MSO customers are afforded a more simplified approach to OBI mitigation and FTTH expansion, one that is compatible with both 1G and 10G EPON and transparent to the existing CATV assets like in-home set top boxes,” claims Hossam Salib, VP of Cable and Wireless strategy at ADTRAN. “MSOs are not only looking for these critical RFoG advantages, but demand an OBI mitigation that avoids constructing centralised cabinets that delay time-to-market and require a large amount of up front capital.”