A RANDOM CODING BOUND FOR FIXED CONVOLUTIONAL-CODES OF RATE 1 N/

We show that the ensemble average of the block error probability for t he ensemble of terminated rate 1/n fixed convolutional codes, used on the binary symmetric channel with a maximum likelihood decoder, is bou nded by exp(2) - NE(r)(1 - K/N), where N = (L + m)n is the block lengt h, L being the message length, K the constraint length, and E(r)() is the random coding exponent for block codes. Hence, E(r)(1 - K/N) > 0 f or H(p) < K/N less than or equal to 1, where H() is the binary entropy function and p is the cross-over probability of the binary symmetric channel.