selective repeat (SR)

The Automatic Repeat Request(ARQ) is an acknowledgement operation for the data block transmission, which knows several procedures for the error message. In addition to the continuous operation, there is also stop-and-wait ARQ, the Selective Repeat( SR) and the Hybrid Automatic Repeat Request( HARQ).

In Selective Repeat, the receiver reports erroneous blocks to the transmitter, which then retransmits them. After the transmission of the erroneous data block, the transmitter continues to transmit in the original sequence.