8
MIMO
8.1 MIMO Channel Model
8.1.1 Fading in Narrowband Channels
In this chapter we consider the transmission via the channels for which the classical model of channel with additive white Gaussian noise (AWGN), with statistically independent errors, mainly caused by the thermal noise at the receiver, is found inadequate and not very useful, since it does not take into account the basic types of errors, arising in such channels, and mainly influencing the receiving quality. Primarily, these are wireless radio channels, in which the effect of interference is more significant than the effect of thermal noise at the receiver. The main reason for communication quality degradation in such channels is the multipath propagation, where, because of reflections from obstacles’ and objects’ motions, the transmitted signal reaches the receiver as a set of interfered responses differing in amplitude, phase, angle of arrival, delay, and so on, that leads to such channel effects as fading and dispersion [3, 7, 31, 35, 43].
The main reasons for multipath propagation effects, as well as the main parameters characterizing such channels are described in Chapter 1, sections 1.3 and 1.4.
In this chapter, the methods for overcoming the dispersion effects in the channel are not considered in detail, so we will mainly consider the effect of fading in the transmission ...
