W Advances in Wireless Terminals

networks have historically been designed primarily to extend the domain of circuit-switched telephone service over a wireless last hop (i.e., cellular telephony). However, wireless networks that support data in addition to voice have now begun to appear. Initially, this has taken the form of circuit-switched and packet-switched data services overlaid on top of existing wireless networks , such as Cellular Digital Packet Data (CDPD) [3] and General Packet Radio Service (GPRS) [4] on top of the Advanced Mobile Phone Service (AMPS) and the Global System for Mobile Communications (GSM), respectively. Emerging third-and fourth-generation wireless networking technologies are now being designed to natively support packet data and multimedia services in addition to voice. These data-and multimedia-capable wireless networks, bootstrap-ping on the success of the Internet and the Web, in turn drive novel networked applications and services for use over the wireless networks. Already, even with the limited data capabilities of the paging network, services such as stock quotes and sports score updates via pager are becoming popular. And this is just the tip of the iceberg. Current wireless terminals, however, are incapable of fully exploiting these emerging integrated service wireless networks. At the present time the choice of wireless terminals is largely limited to simple wireless phones on the one hand, and to complex and bulky laptops or personal digital assistants (PDAs) with built-in or plugged-in wireless cellular and LAN modems on the other. While these devices serve their purposes , they are neither the most integrated nor the most general of solutions, their functionality is often insufficient, and they are generally not unobtrusive enough (i.e., they focus the user's attention too much on the device itself rather than on the task at hand). The search for new wireless devices goes on, as is evidenced by the numerous commercial and research efforts in wireless devices. The natural question, then, is what will the wireless terminals of the future look like? One answer, based on the trendy notion of the " convergence " of the phone and the personal computer (PC), is to marry a palmtop computer or PDA with a phone in the same package. This amounts to an integration effort, albeit a nontrivial one. Early examples include the Nokia 9000 communicator [1] and Bell Laboratories' wireless handset [2]. We believe that such complex one-size-fits-all voice-data integrated wireless terminals are, at best, a partial answer, and will remain point solutions for …