Universal access and management of information has been one of the driving forces in the evolution of computer technology. Central computing gave the ability to perform large and complex computations and advanced information manipulation. Advances in networking connected computers together and led to distributed computing. Web technology and the Internet went even further to provide hyper-linked information access and global computing. However, restricting access stations to physical locations limits the boundary of the vision. The real global network can be achieved only via the ability to compute and access information from anywhere and anytime. This is the fundamental wish that motivates mobile computing. This evolution is the cumulative result of both hardware and software advances at various levels motivated by tangible application needs. Infrastructure research on communications and networking is essential for realizing wireless systems.