Chapter 1. Introduction to Wireless

Wireless networks use radio waves to move data without wires and they have been around in one form or another for decades. Teletype , or telex, systems were established worldwide in the early 1920s. These systems used copper lines to connect two or more teletype machines. Government investments in military radios lead to innovations in radio; teletype over radio (TOR), or radioteletype , replaced many teletype systems, particularly in third-world countries that lacked copper-wire infrastructures . In many parts of the world, TOR is still used as the primary communications medium for governments . TOR uses the high frequency (HF) radio band . We'll cover the types of radio bands later in this chapter.

In 1970, Norm Abramson, a professor of engineering at the University of Hawaii, developed a radio-based communications system known as ALOHANET. This was the world's first wireless packet-switched network, which allows multiple devices to transmit and receive data simultaneously . The research behind ALOHANET was used by Bob Metcalfe to develop the Ethernet standard for wired networking.

Presently, there are many types of wireless networks in use around the world. The 802.11 protocol set, popularly known as Wi-Fi, includes wireless network standards that allow data transmission up to a theoretical 54 Mbps. The Global Positioning System (GPS) uses a wireless connection from a receiver to a series of satellites to fix a location precisely on the planet. There are several wireless networking standards in the mobile-phone world, including General Packet Radio Service (GPRS) and Code Division Multiple Access (CDMA) 1xRTT (1x Radio Transmission Technology). Subsequent chapters will discuss all of these in detail.