Communication Systems is as an introductory textbook, presenting Fourier transform, convolution, and definitions of auorrelation and power spectral density. It also introduces concepts of probability, random variables, and shastic processes and their applications to the analysis of linear systems. Innovatively, the text treats the modulation process using shastic processes as well as covers amplitude modulation, quadrature modulation, angle modulation, mobile cellular systems, propagation channels and more. Quantization and coding of analog signals is also treated, as well as speech coding. Channel modeling, including channel characteristics and propagation, is covered with an emphasis on simple models. Transmission and reception of modulated carriers is included as well as the required transmitting and receiving equipment. Mobile communication is also covered and considers both analog and digital systems. The authors provide five appendices which cover topics such as Fourier series and transforms, Hilbert transform, important formulae, and cellular systems including CDMA and GSM standards. Many examples are provided as well as problems at the end of each chapter to allow the reader to practice his acquired knowledge.