Optimization of Fiber/Coax Upgrades for FITL Systems with Analog and Digital Video Transmission

摘要

This report focuses on identifying key factors which influence the choice of an optimalvideo node size, for a fiber/coax system delivering analog and digital video as an overlay to aFiber-in-the-Loop (FITL) network. The analysis is performed in detail for a 550 MHz networkproviding 37 AM and 100 digital (16-QAM) broadcast channels in addition to fully switcheddigital video. Installed first costs (IFCs) are calculated for a wide range of video node sizes,serving from 32 to 384 homes in a suburban neighborhood. The geographic model, economicassumptions (including 1995 deployment) and most service assumptions are identical to thoseemployed in previous studies of digital baseband and all-digital fiber/coax video networks.The optimal node size under these conditions is found to lie in the range of roughly 100 to300 homes. This differs from earlier studies of all-digital fiber/coax overlays with passive coaxdistribution, which were found to achieve their lowest cost for optical nodes serving about 64homes. Several key parameters affecting the optimal node size are identified, including the costof the analog optical equipment, the level of demand for switched video, the size of the total areabeing served, and the video service penetration. The sensitivity of the per-subscriber cost to theseparameters is explored. The model explains why networks built today for purely broadcast videocan benefit from larger node sizes than are optimal for the network described above. The effectsof going to higher bandwidths and more complicated digital modulation techniques are alsodiscussed.Finally, the per-subscriber cost of the optimized analog/digital network is compared to anall-digital fiber/coax system providing the same services. Despite the more expensiveinfrastructure required for the analog/digital system the total cost, including set-top converters,can be substantially lower than for the digital system, depending on the nature of the servicedemand.