An upper bound on for affine-invariant codes with fixed (Corresp.)

An upper bound on the transmission ratio for binary cyclic codes whose extended codes are invariant under the affine group of permutations, is presented. As a consequence, the transmission ratio of any affine-invariant code with a fixed (minimum weight)/ is shown to approach zero as the code length n increases. This is an extension of the Lin and Weldon result for primitive BCH codes.