Transmission Modes

• Transmissions can occur only in one direction. Sometimes called one-

  way-only, receive-only, or transmit-only.

  Simplex
• Transmissions can occur in both directions, but not at the same time.

  Sometimes called two-way-alternate, either-way, or over-and-out

  systems.

  Half-Duplex
• Transmissions can occur in both directions at the same time.

  Sometimes called two-way-simultaneous, duplex, or both-way line.

  Full Duplex
• Possible to transmit and receive simultaneously, but not necessary

  between the same two locations (i.e. one station can transmit to a

  second station and receive from a third station at the same time).

  Full/Full Duplex
• Echoplex - it is more than half duplex but less than full duplex