Communication uni-directional communication. is a two-way directional communication but one at a time. is a two-way directional communication simultaneously. Sender And Receiver In simplex mode, Sender can send the data but the sender can’t receive the data. In Half-duplex mode, Sender can send the data and also can receive the data one at a time. In Full-duplex mode, Sender can send the data and also can receive the data simultaneously. Channel Usage Usage of one channel for the transmission