Any communications link can be modeled as shown in Figure 1.1, the model having three major components: (1) the source, usually referred to as the transmitter; (2) the transmission channel; and (3) the sink, usually referred to as the receiver, or the destination of the transmitted signals.
Department of Systems and Computer Engineering

Bultitude, R.J.C. (2017). Propagation measurement-based wireless channel characterization and modeling. In New Directions in Wireless Communications Systems: From Mobile to 5G (pp. 1–46). doi:10.1201/b21300