Multiaccess medium

A multiaccess medium is one used for digital communications, to which more than two devices can connect and operate concurrently, with appropriate mechanisms to prevent interferences. Such media are used both for computer networks and telephony, although the communications mechanisms are converging such that there is less and less difference.

There are two types of multiaccess media:

• broadcast (or multicast) capable, in which a participant can send a message to all or part of the other participants, or to any single participant
• nonbroadcast (i.e., nonbroadcast multiple access (NBMA)), in which only one of the participants, or sometimes a small number, can transmit directly to one another.

Multiaccess media include wireless domains divided by radio frequency or other mechanism, as well as physical media such as coaxial cable, optical fiber, or "logical multiaccess" in which the devices connect to one or more interconnection points.