How Much Bandwidth is Enough In the Access Network?

Abstract

When Bell shouted, "Watson, come here!" He probably wanted to debate the design of the 'last mile' of his planned telephone network. Ever since then, telephone engineers and executives have been debating the design of the last mile. The debate continues now with the various FTTX schemes for bringing fiber to within various distances of the customer. In some ways the debate really hasn't changed much - it is still about the economics of each approach - but in a very real way the debate is different now. In the past, this debate was always about POTS, and the economics of various way of providing it. Now it is still about economics, but it is also about - maybe even more so - alternative ways to meet requirements for some very exotic services.

The question is not just, "Which is cheaper?" But also involved are questions such as, "What services will I provide? "How many of each service will the customer need?" "How much bandwidth do I provide for these requirements?" "How will compression advances impact my choices?" The answers to these questions guide the technology choices for the last mile now, at least, as much as economics. This report addresses these issues in light of the activities of the largest telecommunication companies in the US - AT&T, Verizon, and BellSouth. This report starts with a forecast for demand by end users for bandwidth, based on forecasting bandwidth demand of those end users (watching TV, using the Internet, etc.) It then proceeds to review the available designs to provide bandwidth to the access customer, and finally evaluates each provisioning technology against the demand. The results of this analysis are compared to the activities of the large telecom companies and changes in their strategies are forecast.

While this was never a simple debate, the addition of the new unknowns about service requirements makes it a much more complex consideration. To see how complex, one just needs to note that the three (soon to be two) major telcos - Verizon, AT&T and BellSouth - have studied this issue with all of their great resources and come up with three completely different answers!