DATA TRANSMISSION SYSTEM WITH SLIDING-WINDOW DATA FLOW CONTROL

摘要

The invention relates to a digital data transmission system with a non-transparent circuit-switched data connection (V.110) between a transmitting (A) and a receiving party (B), whose nominal data transmission rate may vary during a call. The data connection uses a sliding-window data flow control protocol involving transmission of data frames in a preset order, checking the order of received data frames based on this order information, acknowledgement of properly received data frames and retransmission of incorrect or missing data frames. The transmissing party (A) may temporarily group the data frames, whereby the resulting "wrong" order of frames inside the group or between groups may cause unnecessary retransmissions. In the invention this is eliminated so that the receiving party (B), upon detection of a missing data frame, delays the transmission of a retransmission request for a period of time that will ensure that the missing frame has not been sent later.