Modern Communications A Systematic Introduction

In this chapter we discuss the use of multiple antennas by radios. While the radio links that we discussed up to this point in the text have assumed single-input single-output (SISO) channels, we now consider the use of multiple antennas at both the transmitter (source) and receiver (destination), as indicated in Figure 11.1. We introduce the channel model for a multiple-antenna receiver. We discuss channel estimation and spatial receive beamforming techniques. We introduce the multiple-input multiple-output (MIMO) channel model, define the capacity of this system under the assumptions that the transmitter is uninformed and the transmitter is informed of the channel matrix. Finally, we discuss the concept of space–time coding and present various approaches, including Alamouti’s space–time block code.