Article history: Received 11 April 2011 Revised 13 September 2011 Accepted 14 September 2011 Available online 28 September 2011 Communicated by Jacques Wolfmann

We recall a classic lower bound on the minimum Hamming distance of constacyclic codes over finite fields, analogous to well-known BCH for cyclic codes. This BCH-like serves as foundation proposing some minimum-distance bounds single-generator quasi-twisted (QT) Associating each QT code with an extension field, we obtain first bound. is analogue result in literature quasi-cyclic point out weakne...

In previous works we considered codes defined as ideals of quotients of non commutative polynomial rings, so called Ore rings of automorphism type. In this paper we consider codes defined as modules over non commutative polynomial rings, removing therefore some of the constraints on the length of the codes defined as ideals. The notion of BCH codes can be extended to this new approach and the c...