Terminology (1) Data transmission occurs between transmitter and receiver over some transmission medium Signal: electromagnetic waves -Can propagate along the transmission medium Transmission medium -Guided medium: the signals are guided along a physical path e.g, twisted pair, coaxial cable, optical fiber -Unguided medium: wireless e.g., air, water, vacuum6 Terminology (1) • Data transmission occurs between transmitter and receiver over some transmission medium. • Signal: electromagnetic waves —Can propagate along the transmission medium • Transmission Medium —Guided medium: the signals are guided along a physical path • e.g., twisted pair, coaxial cable, optical fiber —Unguided medium: wireless • e.g., air, water, vacuum