Block transitive codes attaining the Tsfasman-Vladut-Zink bound

Abstract

We study the asymptotic behaviour of a class of algebraic geometry codes, which we call block-transitive, that generalizes the classes of transitive and quasi-transitive codes. We prove by using towers of algebraic function fields with either wild or tame ramification, that there are sequences of codes in this family attaining the Tsfasman–Vladut–Zink bound over finite fields of square cardinality. We give the exact length of each code in these sequences as well as explicit lower bounds for their parameters.