In a half-duplex system, there are still two clearly defined paths/channels, and each party can communicate with the other but not simultaneously
Are the "two clearly defined paths/channels" physical channels?
The multiplexed signal is transmitted over a communication channel, such as a cable. The multiplexing divides the capacity of the communication channel into several logical channels, one for each message signal or data stream to be transferred.
Is "a communication channel" a physical channel?
Is it correct that
- a physical channel can only allow at most one transmission at a time?
- a medium can have multiple physical channels? E.g. a duplex medium has two channels for opposite directional transmissions (see the quote in part 1)?