Data Transmission over a Self-Contained Error Detection and Retransmission Channel

Studies during the last few years have shown that in the transmission of digital data over telephone lines, high accuracy can be achieved when the message is encoded in an error detecting code. Correction can then be accomplished by a repeat transmission of the portion of the information containing the errors. These so-called "feedback" techniques have been shown to be very effective in controlling errors. 1,2,3,4 For some sources of data it is inconvenient or impossible to have the source wait while previous data are being retransmitted. There are also cases where it is required that the output from the receiver be at a uniform rate. This memorandum describes a self-contained error detection and retransmission channel capable of accepting data from the source at a steady rate, or at any rate less than a specified maximum, and of delivering it to the sink at this same rate. The channel is "self-contained," meaning that the channel itself provides enough storage of in375 376 T H E BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1964