Digital libraries bring about the integration, management, and
communication of gigabytes of multimedia data in a distributed
environment.  Digital library systems currently envision users as
being static when they access information.  But it is expected in the
near future that tens of millions of users will have access to a
digital library through wireless access.  Providing digital library
services to users whose location is constantly changing, whose network
connections are through a wireless medium, and whose computing power
is low necessitates modifications to existing digital library systems.
In this paper, we identify the issues that arise when users are
mobile, classify queries that are specific to mobile users and
introduce an architecture that supports flexible and transparent
access to digital libraries for mobile users.  The main features of
the architecture include a layered data representation, support of
adaptability, dual broadcast and on demand querying, caching, and
mobile-specific user interfaces.