 to eliminate a significant number of the ampli- fiers responsible for the failures the network experienced due to power problems in the field. Second, the fiber makes it possible to provision sig- nificantly more bandwidth than coaxial systems allow. Third, because the system is digital, it suffers less from noise-related errors than its analog predecessor did. Finally, an upstream return channel was provi- sioned (see Figure 6-9), which makes possible the delivery of true inter- active services such as voice, Web surfing, and videoconferencing. The third phase of the conversion had to do with the equipment pro- visioned at the user's premises. The analog set-top box has now been replaced with a digital device that has the ability to take advantage of the capabilities of the network, including access to the upstream chan- nel. It decompresses digital content, performs content ("stuff") separa- tion, and provides the network interface point for data and voice devices. The final phase is business conversion. Cable providers look forward to the day when their networks will compete on equal footing with the twisted-pair networks of the telephone company and customers will see them as viable competitors. In order for this to happen, they must demonstrate that their network is capable of delivering a broad variety of competitive services, that the network is robust, that they have oper- Figure 6-9 Upstream and downstream Small channels in Upstream Channel modern cable systems Large (But shared) Downstream Channel Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Access Technologies Access Technologies ations support systems (OSSs) that will guarantee the robustness of the infrastructure, and that they are cost competitive with incumbent providers. They must also create a presence for themselves in the busi- ness centers of the world. Today they are