TECHNOLOGY TO THE RESCUE - OPTICAL ARCHITECTURES FOR INCREASED BANDWIDTH PER USER

摘要

The requirements for segmentation levels (or segmentation granularity) have been continuously evolving and have changed significantly since the first HFC networks were deployed. At that time, the main reasons for building HFC networks were amplifier cascade reduction for improved reliability, better EOL performance and improved network level stability. In the second half of the 1990s, a majority of HFC networks were upgraded to 550 MHz and higher badnwdith. However, after the first fiber deployments, the demand for increased interactive bandwdith per user grew significantly due the success of high-bandwidth interactive services. This paper describes recent progress in some areas of optical and digital technologies that allow a significant increase in interactive bandwidth per user. These technologies enrich the toolbox available to HFC network engineers to increase available bandwidth per user by providing several segmentation alternatives that eliminate the need for additional optical cable construction while reusing existing fibers. Further, we describe some of the optical components that permit significant reduction in the cost of segmentation, the components having been developed for these applications with emphasis on their robustness and flexibility. This paper also presents segmentation alternatives that take advantage of these new technologies. Several scenarios are possible. Nodes in areas previously upgraded can be segmented to allow independent forward and upstream paths without the need for upgrade in the fiber and RF coax part of the network. Hence, the capacity per user can be increased without significant capital expenditures. In areas where nodes with a large number of homes per node were deployed earlier, or in new communities growing outside of the existing boundaries, the capacity per user can be readily increased by adding new nodes without adding new fibers on the existing fiber routes and without costly bandwidth upgrades in the RF coax part of the network. Yet in other areas when the network is newly built or rebuilt for the reasons of inadequate cable, bandwidth or components, and in some areas of extensive upgrades, a node architecture with superior capacity per user can be deployed. This paper presents capital cost savings realized by deploying these solutions with real life examples. Finally, we describe some feedback from field deployments of the segmentation alternatives and the enabling features of the node technology that allow easy alignment and maintenance.