device ue 1 ue 2 ue 3 belongs are shown with a solid line while the transport channels trch 1 trch 2 trch 3 of the multicast groups mc 1 mc 2 mc 3 to which a mobile radio device does not belong are shown with a broken line the transport channels trch 1 trch 2 trch 3 of the multicast groups mc 1 mc 2 mc 3 on which data is transmitted within a considered time interval tti are shown with solid bold lines allocation of the downlink shared channel dsch resource that is when data for a specific multicast group mc 1 mc 2 mc 3 is transmitted on the dsch and the parameters for said transmission is effected according to the present invention in particular via a common channel associated with the dsch channel type to which all mobile radio devices ue 1 ue 2 ue 3 registered with one of the multicast groups listen when data of a specific multicast group mc 1 mc 2 mc 3 is transmitted a transport format combination indicator tfci value is transmitted on this common channel providing information about the physical channel via which the dsch is transmitted and about the transport format combination tfc to be used for this purpose the transport format combination indicator tfci value identifies a calculated transport format combination ctfc value in a table configured beforehand according to the inventive method the transport format combination tfc to be used then may be calculated back from this calculated transport format combination ctfc value the tables in fig2 to 4 show the assignment of transport format.