A communication system is disclosed in which communication devices communicate with a base station using radio frames made up of a sequence of subframes and a frequency band made up of frequency subbands. The base station identifies a subframe in which a broadcast message, carrying information for at least one communication device, is to be broadcast; transmits, in a control channel, in a frequency subband in a current subframe that precedes the identified subframe, control information to identify said subframe in which said broadcast message is to be broadcast; and transmits the broadcast message in the identified subframe.