Automatic retransmission rather than automatic repeat request

The standard HDLC family of protocols has been designed for low to moderate BERs. But as BER increases frequent losses or corruptions of certain frames will cause extensive timeout recovery. Too many timeouts means low throughput. A new retransmission scheme is presented which depends on the transmitter to automatically initiate retransmission instead of the conventional way where the receiver automatically requests retransmission. The retransmission strategy is based on two ideas: the receiver can report without any restriction its buffer status by using a multiple acknowledgement frame and the transmitter keeps a record of the transmission order in which frames were sent. This new approach significantly reduces the use of timeout recoveries, and hence it gives a higher throughput efficiency than the standard and extended HDLC protocols. >