1. Introduction to Radio Systems

In this chapter, an overview of wireless communication systems is presented. We begin with a definition of the fundamental wireless communications problem and motivate approaches to its solution. Following definitions of carrier, baseband, and modulation, the simplified block diagram of a transmitter, together with a description of its typical building block elements, is presented. We then focus on the mathematical description and corresponding spectral properties of amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). This is followed by a study of differences among modulation schemes, their bandwidth, and their vectorial representation. In particular, the separate cases of narrow- and wideband FM, and phase modulation (PM) are addressed.