Reliable data transmission through noisy media ¿ A systems approach

Error control techniques are becoming increasingly important in data transmission systems, since they allow reliable communications over media where the interference is high. Transmission errors can be corrected either by adding redundancy bits to the information to generate an error correcting code, or by automatically retransmitting the message when erroneously received. The relative merits of the two techniques are discussed in terms of both error control and systems compatibility. A class of powerful and easily implemented cyclic error detection and correction codes was recently developed which, in combination with automatic retransmission, should give effective error protection. Once the system reliability requirements are realistically gauged, and the characteristics of the channel interference are known, it is possible to determine a cyclic code best suited to that interference, and to determine a message length for the maximum transfer of information.