A Short Answer

Take a look at your iPhone, Android phone, or a smartphone running on some other operating system. It embodies a remarkable story of technology innovations. The rise of wireless networks, the Internet, and the web over the last five decades, coupled with advances in chip design, touchscreen material, battery packaging, software systems, business models… led to this amazing device you are holding in your hand. It symbolizes our age of networked life.

These phones have become the mobile, lightweight, smart centers of focus in our lives. They are used not just for voice calls, but also for data applications: texting, emailing, browsing the web, streaming videos, downloading books, uploading photos, playing games, or video-conferencing friends. The throughputs of these applications are measured in bits per second (bps). These data fly through a cellular network and the Internet. The cellular network in turn consists of the radio air-interface and the core network. We focus on the air-interface part in this chapter, and turn to the cellular core network in Chapter 19.

Terrestrial wireless communication started back in the 1940s, and cellular networks have gone through generations of evolution since the 1970s, moving into what we hear as 4G these days. Back in the 1980s, some estimated that there would be 1 million cellular users in the USA by 2000. That turned out to be one of those way-off under-estimates that did not even get close to the actual impact of networking technologies.