In a radio communication system including a plurality of subscriber stations and at least one radio access device, useful information of a group of subscriber stations is transmitted by radio. A number of subscriber stations of the group is located in the radio coverage area of the at least one radio access device. The at least one radio access device notifies the subscriber stations of the number of subscriber stations of the group before the useful information is transmitted, using a radio resource. The notification contains information relating to at least one signal in the transmission of the useful information transmitted via another radio resource.