Support for Internet Information Services on Digital Audio Broadcast Networks

Duncan McPherson, School of Computer Science, University of St Andrews, Scotland

Dr Dirk Husemann, IBM Research, Zurich, Switzerland

Extended Abstract

This paper investigates the use of Digital Audio Broadcast (DAB) radio technology 
for the efficient distribution of World Wide Web Internet content to mobile wireless 
clients. Many popular web sites remain static for a day or longer, which makes them 
particularly suitable for this type of broadcast distribution. The design and 
development of a complete working reference system - DABWeb - is described. 
DAB is a unidirectional broadcast standard so the usual Internet protocols which 
facilitate reliable transmission and user navigation on the Web are not available. 
These requirements are addressed by client-side caching and server-side scheduling 
schemes. The concept of pseudo-interactive Web surfing is introduced. Transmissions 
are encrypted and customers are supplied with smart cards which decrypt information 
being received, allowing DABWeb service providers to charge. In contrast to the Public 
Key style of cryptography, a symmetrical Remote Key algorithm - BEAST RK - is adopted. 
Bounds on the time needed for decryption operations to complete in order to cope with 
broadcast transmission data rates are derived.

The choice of web content to be broadcast is made by the DABWeb service provider. 
It is anticipated that Internet content providers (e.g. newspapers) would enter 
into distribution agreements with the owners of DAB networks. Some bandwidth might 
also be made available to educational institutions and the encryption feature of 
DABWeb used to target broadcasts to specific student groups. It is also hoped that 
users of encrypted DABWeb services could benefit by the increased quality of content 
available since they are paying for the service.

A DABWeb client enhances the availability of web content to the user by downloading 
whenever possible and it is anticipated that DABWeb clients will have large multi 
megabyte caches available to them. Present DABWeb clients makes use of a simple 'cache 
as much as possible' algorithm, with files being cached for a fixed time period, or 
until they are overwritten by a broadcast containing a more recent web site version. 
Since web sites distributed using DABWeb may contain hyperlinks to sites not being 
broadcast, wireless DABWeb clients could also make use of another duplex wireless 
technology to allow users to surf outwith the DABWeb cache. In this way a low cost 
DABWeb system could be complimentary to other forms of more expensive wireless 
Internet access - with the added bonus of allowing users to receive DAB radio 
programs.

The DABWeb system presented here represents a laboratory scale prototype, which is 
still under development. In the near future it is hoped to hold a much larger scale 
trial to better evaluate the use of the system in some of the scenarios described 
above.

Speaker Biography

Duncan McPherson is currently finishing his BSc(hons) and MPhil degrees at St Andrews 
University in Scotland. He recently spent ten months working in Switzerland for IBM 
Research on the DABWeb project, and has written his Master's thesis on this topic. 
Previously he has also worked for Philips Research, and as a freelance writer for 
newsstand computer magazines.