Retransmission Error Control

This paper discusses a simple, easily implemented form of retransmission error control; namely, the use of vertical and horizontal block parity checks. The method discussed provides a level of error rate performance which is far better than that which can be expected from the equipment into which it must operate. For instance, for a random bit error probability of 10⁴, a 22 × 22 bit block yields an output error rate of , with an efficiency of 87 per cent. This form of retransmission error control, therefore, represents the basic method against which other methods can be compared and evaluated. An analysis is presented which determines the parameters for optimum performance for both random and bunched errors.