TABLE OF CONTENTS Adaptive antennas have been used for decades in areas such as radars, satellite communications, remote sensing, and direction finding, to name a few. For instance, radar and secure communications systems take advantage of the ability of these antennas to adapt to the operating environment to combat jamming. Satellite communications systems have used multiple beam and spot beam antennas for years to tailor their coverage to specific geographic locations. Each of these applications is associated with its own unique set of challenges, such as the channel in which the system operates, the propagation environment, sources of interference, and noise or jamming. In addition, the end goal for which the adaptive antenna is used affects the selection of the type of array, size, adaptive algorithms, and integration with other system components. In this chapter we provide a summary of the status of current mobile cellular communications systems, their various evolution paths, mobile systems growth potentials, as well as an introductory discussion of the benefits and use of smart antennas in 3G cellular communications systems.
In the 1980s and 1990s, wireless cellular and personal communications systems (PCS) began to flourish with the advent of second generation mobile communications systems, or simply 2G, to cope with increasing demands. Early mobile communications systems were based on analog technologies that used frequency division multiple access (FDMA). In multiple access, a number of users access or share the resources of a common source. In FDMA systems, the available spectrum is divided into...
