A simple algorithm is presented for finding rate 1/n random-error-correcting convolutional codes. Good codes considerably longer than any now known are obtained. A discussion of a new distance measure for convolutional codes, called the free distance, is included. Free distance is particularly useful when considering decoding schemes, such as sequential decoding, which are not restricted to a fixed constraint length. It is shown how the above algorithm can be modified slightly to produce codes with known free distance. A comparison of probability of error with sequential decoding is made among the best known constructive codes of constraint length 36.
No takes yet. Share an insight, caveat, or question.
Daniel J. Costello (1969) studied this question.