Question about fading
Consider two random variables $x \sim N(0, \sigma^2)$  and $ y \sim N(0, \sigma^2)$. 
Then $h = \sqrt{x^2 + y^2}$ is Raylegh-distributed with parameter $\sigma$, whose p.d.f is

$$
f(h) = \frac{h}{\sigma^2} \exp(-h^2/2\sigma^2)
$$ 

According to Wikipedia,

$$
\Omega = E[h] = \sigma \sqrt{\frac{\pi}{2}}  \implies  \Omega \propto \sigma
$$

Hence, the range of $\Omega$ depends on the variance of your input signals $x$ and $y$. If you think of $x$ and $y$ as "signal + AWGN", then $\sigma$ is essentially the signal-to-noise ratio. So, whether $\Omega &lt; 1$ or $\Omega &gt; 1$ depends on whether you are modelling low SNR conditions or high SNR conditions, respectively.