Prerequisites

This chapter builds on linear algebra (Chapter 1), probability (Chapter 2), signals and systems (Chapter 4), and large-scale propagation (Chapter 5).

Complex random variables and distributions(Review ch02)
Self-check: Can you compute the PDF of $|Z|$ where $Z = X + jY$ with $X, Y \sim \mathcal{N}(0, \sigma^2)$ i.i.d.?
Fourier transforms and LTI systems(Review ch04)
Self-check: Can you compute the output PSD given the input PSD and the system transfer function $H(f)$ ?
LTV systems and Doppler spread (Section 4.5)(Review ch04)
Self-check: Do you understand how a time-varying impulse response $h(\tau; t)$ relates to the Doppler spread function?
Large-scale path loss and shadowing(Review ch05)
Self-check: Can you distinguish between large-scale fading (path loss + shadowing) and the small-scale fading covered in this chapter?

Key symbols introduced or heavily used in this chapter.

Symbol	Meaning	Introduced
$h(\tau; t)$	Time-variant channel impulse response	s02
$H(f; t)$	Time-variant transfer function	s06
$S_H(\tau; \nu)$	Delay-Doppler spread function (scattering function)	s06
$K$	Ricean K-factor (LOS-to-scattered power ratio)	s03
$f_D$	Maximum Doppler shift $= v/\lambda = vf_0/c$	s04
$T_c$	Coherence time	s04
$\sigma_\tau$	RMS delay spread	s05
$B_c$	Coherence bandwidth	s05
$r(t)$	Fading envelope	s03
$\Omega$	Mean received power $= E[r^2]$	s03