modes of channel operation - Simplex, Half-Duplex and Full Duplex
Simplex Data in a simplex channel is always one way. Simplex channels are not often used because it is not possible to send back error or control signals to the transmit end. It's like a one way street. An example of simplex is Television, or Radio. The simplex channel also corresponds directly to Shannon's model of communication discussed earlier. Half Duplex A half-duplex channel can send and receive, but not at the same time. It's like a one-lane bridge where two way traffic must give way in order to cross. Only one end transmits at a time, the other end receives. In addition, it is possible to perform error detection and request the sender to retransmit information that arrived corrupted. In some aspects, you can think of Internet surfing as being half-duplex, as a user issues a request for a web document, then that document is downloaded and displayed before the user issues another request. Another example of half-duplex is talk-
