A CLASS OF CONSTACYCLIC BCH CODES WITH LENGTH qm+1 2

As a generalization of BCH codes, constacyclic BCH codes have become a good source for constructing optimal codes. However, the param-eters of these codes are not easy to determine in general. In this paper, we investigate the parameters of a class of q-ary constacyclic BCH codes with length qm+1 2 and compute their exact dimensions in some ranges of designed distance. In particular, we study the parameters of constacyclic BCH codes with the designed distance in a larger range than known results.