2.1 Introduction

Since the late 1990s, the cellular industry and the business press have promoted wireless Internet as "the next big thing" in information technology. The idea was compelling in view of the huge public appetite for cellular telephones and the Web in the 1990s. The enthusiastic predictions of the growth of the wireless Internet were linked to two emerging technologies:

Third-generation (3G) cellular systems that would overcome the bit rate bottleneck of existing technology.
Internet-enabled cell phones that within a few years would be more numerous than personal computers.

As we write this chapter three years later, we are drawn to the adage "the future isn't what it used to be." Instead of cellular modems, the preferred mode of wireless access to the Internet in 2002 is a WLAN (wireless local area network) plug-in card or a WLAN modem built into a notebook computer. In limited coverage areas, WLANs give stationary (or slowly moving) users of notebook computers access to the two "killer apps" (mass-market applications) of the Internet: the Web and e-mail. In wide coverage areas (metropolitan and national), specialized wireless data networks and cellular networks transfer e-mail to and from PDAs (personal digital assistants) and specialized e-mail terminals. The most popular PDAs use the Palm operating system. Blackberry is a popular specialized e-mail terminal.

Simultaneous with the rapid growth of WLAN usage, the cellular industry is cautiously inaugurating 3G networks in Europe and Asia, and upgrading second-generation systems with "2.5G" (enhanced digital cellular) technology in many countries. In parallel with the cellular and WLAN radio developments, there is a high volume of activity in the Internet community focused on extending existing Internet protocols and introducing new ones with the aim of accommodating mobility and the characteristics of radio communications.

This chapter focuses on trends in wireless communications aimed at promoting a wireless Internet. The following section introduces a framework for comparing different wireless Internet radio technologies and describes the evolution of cellular systems and WLANs. The emerging technologies will overcome some of the deficiencies of mobile wireless communications relative to the transmission technologies of the wired Internet. However, even after these evolutionary measures mature, many gaps will remain between expectations for a wireless Internet and what can be achieved in practice. The remainder of the chapter describes work in progress to overcome these gaps and create a wireless Internet that is more than the present Internet with some of the wires eliminated. Section 2.3 suggests an approach to advancing beyond the technologies emerging in 2002, and Section 2.4 describes research in progress that follows this approach.