Generation of ray class fields of imaginary quadratic fields

Let K be an imaginary quadratic field other than Q(sqrt(-1)) and Q(sqrt(-3)), and let O_k be its ring of integers. Let N be a positive integer such that N=5 or N≥7. In this paper, we generate the ray class field modulo NO_K over K by using a single x-coordinate of an elliptic curve with complex multiplication by O_K.