Overview

Since the telephone was invented in the late nineteenth century, there has been a steady development of telephone services, and the number of subscribers has continuously increased. One of the most revolutionary developments in telephone service in the late twentieth century was the introduction of the cellular variety of mobile phone services. As the number of subscribers has explosively grown in the wireless communication systems, provision of the mobility in telephone service was made possible by the technique of wireless cellular communication. As the bandwidth over the wireless link is a scarce resource, one of the essential functions of wireless communication systems is multiple access technique for a large number of users to share the resource.

Conceptually, there are mainly three conventional multiple access techniques: FDMA, time division multiple access (TDMA), and CDMA, as illustrated in Figure 1.1. The multiple access technique implemented in a practical wireless communication system is one of the main distinguishing characteristics of the system, as it determines how the common transmission medium is shared among users. FDMA divides a given frequency band into many frequency channels and assigns a separate frequency channel on demand to each user. It has been used for analog wireless communication systems. The representative FDMA wireless cellular standards include Advanced Mobile Phone System (AMPS) in the United States, Nordic Mobile Telephones (NMT) in Europe, and Total Access Communications System (TACS) in the United Kingdom ^[1]. TDMA is another multiple access technique employed in the digital wireless communication systems. It...