Wireless Transceiver Architecture

2 The Electromagnetism Point of View

Given that a wireless system relies on the propagation of electromagnetic waves for the transmission of information, we discuss the minimum set of functions to be implemented in a transceiver, as derived in Chapter 1, by considering the theory of electromagnetism. This theory highlights why electrical power has to be delivered to the radiating element on the transmit side, whereas the processing of either voltage only or current only waves remains sufficient for recovering the information on the receive side. It also allows us to detail some constraints to be considered for dimensioning a receive line-up due to the dynamic behavior of the propagation channel in a mobile environment. This review of results from the electromagnetic theory also allows us to understand the effective behavior of a wireless link, i.e. how information propagates up to the receive side through the modulation of the electromagnetic field. Our interest in considering such theoretical aspects is thus twofold.

2.1 Free Space Radiation

Let us begin by focusing on free space radiation. Our interest in this comes not only from the guidelines that can be derived for transceivers, but also from the fact that it illustrates how a wireless system behaves in general. We detailed in Chapter 1 the signal processing functions that allow us either to generate an RF bandpass waveform that embeds the information to be transmitted from a given modulating waveform, or to recover ...