Rapid changes in quality imply the need for highly adaptive applications that can possibly even support disconnected operation, implying a level of autonomy.
Wireless links are less secure.
Because of mobility, location dependent information can exist - resource discovery, privacy, and the migration of locality become import issues. This paper attacks mobile computing from a computer science perspective, focusing on the impact of wireless communications on network properties, systems properties, and properties visible to the end-user. As promised by the title of the paper, challenges are presented, not solutions. Data services are overemphasized and voice services largely ignored. This is, however, consistent with the computer-science perspective put on the paper.