Inserting virtual carrier in conventional ofdm host carrier in communications system

A base station for communicating data to and from a plurality of mobile terminals over a plurality of OFDM sub-carriers within a coverage area provided by the base station, the base station arranged to allocate transmission resources provided by a first group of the plurality of OFDM sub-carriers within a first frequency band to mobile terminals of a first type and to allocate transmission resources provided by a second group of the plurality of OFDM sub-carriers within a second frequency band to terminals of a second type, the second group being smaller than the first group and the second frequency band being selected from within the first frequency band, and

• to transmit control information comprising resource allocation information for terminals of the first type over a first bandwidth corresponding to the combined first and second groups of OFDM sub-carriers and to transmit control information comprising resource allocation information for terminals of the second type over a second bandwidth corresponding to the second group of OFDM sub-carriers.