Several mobile station identifiers are allocated to one mobile station, one for each of a plurality of possible signalling channel structures, parameters, or both. When receiving the signalling channels, the mobile station searches for all identifiers allocated for it in the received signalling channels. When it finds one that matches, it may for instance check a mapping table (agreed at the connection setup between mobile station and the network by RRC signalling) to determine what this identifier means. The signalling channel structure, parameters, or both, used in the transmission may be implicitly or explicitly indicated by the identifier. The mobile station (User Equipment) should monitor the signalling channels in the normal way. Instead of looking for only one identifier, however, the mobile station should monitor several identifiers belonging to it.