The Digital Communications Point of View

When detailing how to dimension a transceiver, it can seem natural to first clarify what is expected from such a system. This chapter focuses on the consequences for transceiver architectures of the signal processing associated with the digital communications. The concept of the complex envelope is of particular importance as the lowpass signal embeds all the statistical characteristics of interest of the modulated bandpass RF signal it represents. The chapter points out that such complex envelopes have additional practical advantages over the use of real bandpass signal representations when performing analytical derivations. It also discusses the bandpass concept for noise signals as classically encountered in practical transceivers. Finally, the chapter reviews some digital modulation schemes that are representative of the different statistics that can be encountered in classical wireless standards.