The course covers the properties and functions of digital communication systems. The first part provides a recap on signal description in the time-domain and frequency domain, stochastic and deterministic signals, and digital signal processing. Based on these foundations, various aspects of modern digital communication are considered. The concept of noise is introduced. System components of communication systems (mixers, filters, etc.) are discussed. Spread spectrum and channel access technologies are introduced (OFDM, CDMA, ...). Basics of information theory and coding are considered as well as challenges of communication over wireless transmission channels.