Using the World Wide Web at 28.8 Kbps (or less) can be a frustrating experience: a multimedia page that takes a fraction of a second to download at Ethernet speeds takes many seconds at modem rates. Two enhancements to existing infrastructure have the potential to deliver more satisfactory residential Internet access: ISDN telephone service, and upgraded cable TV networks.
While ISDN dedicates bandwidth to each user, cable networks support a shared bandwidth approach similar to that used in computer Local Area Networks (LANs). This report describes the technologies and evaluates qualitative differences between the two approaches. It presents quantitative results of capital cost models based on case studies of the PSICable deployment in Cambridge, MA, and the Internet over ISDN service offered by Internex, Inc. in the San Francisco, CA area.
The report finds that cable's shared-bandwidth approach has superior economic characteristics. For example, 500 Kbps Internet access over cable can provide the same average bandwidth and four times the peak bandwidth of ISDN access for less than half the capital cost per subscriber. The economy of the shared bandwidth approach is most evident when comparing the per-subscriber cost per bit of peak bandwidth: $0.60 for the 500 Kbps cable service versus close to $16 for ISDN. Cable-based access also has better service characteristics: it can support both full-time Internet connections and higher peak bandwidths, such as a 4 Mbps cable service that provides thirty-two times the peak bandwidth of ISDN.
The report concludes with an analysis of the barriers to diffusion of cable and ISDN Internet access, including business and policy factors. It finds that the closed market structure for cable subscriber equipment has not been as effective as the open market for ISDN equipment at fostering the development of needed technology. Furthermore, monopoly control of residential communications infrastructure--whether manifest as high ISDN tariffs or simple lack of interest from cable operators--limits business opportunities for Internet service providers.
This research was funded by ARPA's "Interface Technologies for Networked Computing" project, number N00174-93-C-0036, ARPA's "Design and Development of Distributed Video Systems" project, number F30602-92-C-0019, and a grant from Siemens Corporation.
Caveat: this report is 197 pages long and includes many figures. Binhex (.hqx) appears to be the most universally successful format for downloading; postscript often causes problems, but the adventurous are welcome to try. If you have difficulty downloading or would prefer to leave the large printing job to someone else, you can order a bound copy from pubs@lcs.mit.edu (available mid-to-late June, 1995). It will be available to you at cost, probably somewhere between $20 and $30 (international orders cost more because of mailing). Copies of the original thesis are also available now, again at cost, from the MIT Research Program on Communications Policy.
