Designing Wireless Information Services

Wireless technology is gaining popularity very rapidly. Many predict a new emerging market where millions of mobile users will carry small, hand-heldterminals, capable of communicating over a wireless connection. Mobile users will mostly need location dependent information such as local yellow pages, traffic reports, shopping information, local directions, etc. Mobility, bandwidth and energy limitations are the main new factors which have to be taken under consideration in the design of wireless information services. Three basic modes of wireless information dissemination are defined: (1) publishing, (2) delta publishing, and (3) on demand. The publishing mode is the most energy efficient scheme as it does not require the clients to submit uplink requests to the Mobile Support Station (MSS) but just listen to the downlink stream of data periodically broadcast by the MSS on its downlink channel. However, data which is published has to be very carefully organized and multiplexed with the directory information. Tradeoffs between different dissemination modes are investigated, with the goal of developi ng energy efficient access methods from battery powered clients. Different caching strategies in the context of frequent client disconnections are also investigated. Finally, the implementation of the above methods in the form of prototypical wireless information server (kiosk) is provided.