Communication Systems introduces Fourier transform, convolution and definitions of autocorrelation and power spectral density. It also introduces concepts of probability, random variables, and stochastic processes and their applications to the analysis of linear systems. In addition, the book covers speech coding, amplitude modulation, quadrature modulation, angle modulation, mobile cellular systems, propagation channels and more. The book also includes five appendices which cover topics such as Fourier series and transforms, Hilbert transform, formulas used in the text, GSM cellular system and others.