FINDING AN ASYMPTOTICALLY BAD FAMILY OF q-TH POWER RESIDUE CODES
In coding theory, we are often interested in finding codes with a "good" relative minimum distance. To create a code that transmits information efficiently, we would like to see the ratio of bits containing information to total codeword length be large. In particular, for families of codes this means that as the codeword length increases, we do not significantly decrease the amount of information transmitted; for each fixed prime q we can construct a family of q-ary codes with lengths p and minimal distances d(p) with the property that as the length of these codes approaches infinity, the ration of their minimal distance to their total length tends towards epsilon > 0. In this paper, we examine families of generalized binary quadratic residue codes, named q-th power residue codes, where q is a fixed odd prime, and find an asymptotically bad subfamily of these codes. For each prime l we will construct a q-th power residue code of length p (determined by our choice of l) and minimal distance d(p), with the property that as l approaches infinity, p also tends towards infinity, and lim(l ->infinity) d(p)/p = 0.
coding theory quadratic residue codes chebotarev's density theorem