Introduction

This chapter presents a case for the 5G and motivation for writing the book. It summarizes a few of the key developments in 3rd Generation Partnership Project long‐term evolution. The chapter introduces the capacity regions of multiuser cellular network by defining three basic channels in the multiuser network, namely: multiple access channel, broadcast channel, and interference channel. It also presents a brief overview of the different types of fading channels, which are most commonly used in practical mobile communications. The chapter discusses an important issue associated with mobile communications, that is the impact of CO
₂
emissions by active mobile networks. It describes a base‐station power consumption model that includes contribution from power amplifier, small signal radio frequency transceivers, baseband units, power supply, and system active cooling. The chapter considers the carbon emissions due to cellular networks and examines the possibilities of green heterogeneous network.