Communication Systems is a comprehensive book for undergraduate students of Electronics and Communications and Computer Science Engineering. The book comprises chapters on representation of signals and systems, continuous-wave modulation, pulse modulation, baseband pulse transmission, digital passband transmission, spread-spectrum modulation, and error control catalog. In addition, the book consists of plenty of examples, computer-based questions, and chapterwise questions to understand the concepts better. The book also features eight computer experiments using MATLAB. This book is essential for engineering students preparing for competitive examinations like GATE and IES.