On the dimension of SSRS codes

A subspace subcode of Reed-Solomon (SSRS) code (Hattori et al. 1998) is a subcode of a Reed-Solomon (RS) code (called the parent code) over F/sub p/m consisting of codewords whose components all lie in a fixed v-dimensional (over F/sub p/; p- a prime) vector subspace V of F/sub p/m. In this paper we present a formula for the cardinality of an SSRS code by viewing V as an [m,v] linear code over F/sub p/ with parity check matrix H. Our formula is in terms of H and counting the endomorphisms of F/sub p/m satisfying certain conditions resulting from the DFT domain characterization of SSRS codes.