The Automatic Repeat Request (ARQ) is an acknowledgement operation for the data block transmission, which knows several procedures for the error message
. Inaddition to the continuous operation, there is also stop-and-wait ARQ, the Selective Repeat (SR) and the Hybrid Automatic
With the Selective Repeat, the receiver reports faulty blocks to the transmitter, which then retransmits them. After the transmission of the faulty data block, the transmitter continues to transmit in the original sequence.