Error-control techniques for data communication

A review of available techniques for increasing reliability in data communication links is presented. The methods all include error correction and retransmission (ARQ), and attention is focused on redundancy of transmission being activated only after errors have been detected. ARQ is currently performed in stop-and-wait or continuous modes. The continuous mode consists of blocks of data transmission followed by responses, both numerically defined so that data blocks can be transmitted in bursts while a response to an initial transmission is being sent. Negatively acknowledged (NACKed) blocks with errors are transmitted a second time, while error-free acknowledgements (ACKs) are transmitted only once. Data blocks are stored in a buffer memory, which will reject even correct blocks if filled. A data link, transmitter, receiver, and algorithm are described for optimized data transmission.