what is the difference between transmission medium and communication channel?
A transmission medium (plural transmission media) is a material substance (solid, liquid or gas) which can propagate energy waves. For example, the transmission medium for sound received by the ears is usually air, but solids and liquids may also act as transmission media for sound. Channel, in communications (sometimes called communications channel), refers to the medium used to convey information from a sender (or transmitter) to a receiver. A channel can take many forms, including ones suitable for storage which can communicate a message over time as well as space. Examples of communications channels include: 1. A connection between initiating and terminating nodes of a circuit. 2. A buffer from which messages can be put and gotten. See Actor model and process calculi for discussion on the use of channels. 3. A single path provided by a transmission medium via either * physical separation, such as by multipair cable or * electrical separation, such as by frequency-division or time-d
