Simplex and Duplex Channels
In a simplex transmission, one device acts as the transmitter and a second device acts as the receiver. Data flows in one direction only, whereas in a duplex channel, the communication is bi-directional. Full-duplex transmission uses two separate communication channels so that two communicating devices can transmit and receive data at the same time. Data can flow in both directions simultaneously. Half-duplex transmission is a compromise between simplex and full-duplex transmission. A single channel is shared between the devices wishing to communicate, and the devices must take turns to transmit data. Data can flow in both directions, but not simultaneously.