Short unit-memory byte-oriented binary convolutional codes having maximal free distance (Corresp.)
Lin‐Nan Lee · IEEE Transactions on Information Theory · 1976
It is shown that(n_{o},k_{o})convolutional codes with unit memory always achieve the largest free distance among all codes of the same ratek_{o}/n_{o}and same number2^{Mk_{o}of encoder states, whereMis the encoder memory. A unit-memory code with maximal free distance is given at each place where this free distance exceeds that of the best code withk_{o}andn_{o}relatively prime, for allMk_{o} \leq 6and forR = l/2, 1/3, 1/4, 2/3. It is shown that the unit-memory codes are byte oriented in such a way as to be attractive for use in concatenated coding systems.