A base station includes a controller configured to configure an MRS resource set comprising a group of MRS resources, each MRS resource comprising a set of MRS antenna ports. If at least two MRS antenna ports belong to a same MRS resource, then the at least two MRS antenna ports are quasi co-located with respect to a first set of QCL parameters, else if the at least two MRS antenna ports belong to a same MRS resource set, then the at least two MRS antenna ports are quasi co-located with respect to a second set of QCL parameters, and else the at least two MRS antenna ports are not quasi co-located with respect to either the first set or the second set of QCL parameters. The MRS is a CSI-RS for estimating a CSI and at least one of the first set and the second set of QCL parameters.