## Appendix B Probability Distributions In Communications

### B.1 Uniform Distribution

A random variable uniformly distributed between *a* and *b*, where *a < b*, has a probability density function (PDF) given by

The mean is given by

and the variance is given by

### B.2 Gaussian Distribution

The Gaussian distribution is ubiquitous throughout science and engineering. The Gaussain distribution is also called the *normal* distribution. A Gaussian random variable has a PDF given by

where μ is the mean and *a*^{2} is the variance. For zero mean and unity variance, the ...