Further results on binary convolutional codes with an optimum distance profile (Corresp.)

Fixed binary convolutional codes are considered which are simultaneously optimal or near-optimal according to three criteria: namely, distance profile , free distance , and minimum number of weight paths. It is shown how the optimum distance profile criterion can be used to limit the search for codes with a large value of . We present extensive lists of such robustly optimal codes containing rate nonsystematic codes, several with superior to that of any previously known code of the same rate and memory; rate systematic codes; and rate nonsystematic codes. As a counterpart to quick-look-in (QLI) codes which are not "transparent," we introduce rate easy-look-in-transparent (ELIT) codes with a feedforward inverse . In general, ELIT codes have superior to that of QLI codes.