Communication apparatus for a communication system, wherein the communication apparatus comprises: a transceiver configured to communicate with a plurality of communication devices (3-1, 3-2); a controller for operating a cell having a cell bandwidth; wherein the controller is operable to: treat said cell bandwidth as a plurality of non-overlapping band portions, each band portion comprising a respective set of resource blocks that occupy a narrower frequency bandwidth than said cell bandwidth, and each band portion having a respective index for identifying that band portion; obtain: i) an index of a band portion for use by at least one communication device (3-1, 3-2) of the plurality of communication devices (3-1, 3-2); and ii) information for identifying an allocation of at least one resource block within the band portion for use by the at least one communication device (3-1, 3-2); and generate, from said obtained index and said information for identifying an allocation, control data for uniquely identifying a position of the allocation of at least one resource block, within said cell bandwidth; and wherein the transceiver is operable to signal the control data to the at least one communication device (3-1, 3-2), wherein the plurality of non-overlapping band portions comprises a plurality of equally sized band portions, wherein when the obtained index is an index of one of the equally sized band portions, the controller is further configured to generate the control data for uniquely identifying a position of the allocation of at least one resource block by jointly encoding the obtained index and the information for identifying an allocation to form jointly encoded control data, wherein the jointly encoded control data is derived using the following formula: JESRIV = RIV + 21 ∗ k where JESRIV is the jointly encoded control data; k is the obtained index; and RIV is the information for identifying an allocation and comprises a unique value representing an allocation of at least one resource block within band portion k. a transceiver configured to communicate with a plurality of communication devices (3-1, 3-2); a controller for operating a cell having a cell bandwidth; wherein the controller is operable to: treat said cell bandwidth as a plurality of non-overlapping band portions, each band portion comprising a respective set of resource blocks that occupy a narrower frequency bandwidth than said cell bandwidth, and each band portion having a respective index for identifying that band portion; obtain: i) an index of a band portion for use by at least one communication device (3-1, 3-2) of the plurality of communication devices (3-1, 3-2); and ii) information for identifying an allocation of at least one resource block within the band portion for use by the at least one communication device (3-1, 3-2); and generate, from said obtained index and said information for identifying an allocation, control data for uniquely identifying a position of the allocation of at least one resource block, within said cell bandwidth; and treat said cell bandwidth as a plurality of non-overlapping band portions, each band portion comprising a respective set of resource blocks that occupy a narrower frequency bandwidth than said cell bandwidth, and each band portion having a respective index for identifying that band portion; obtain: i) an index of a band portion for use by at least one communication device (3-1, 3-2) of the plurality of communication devices (3-1, 3-2); and ii) information for identifying an allocation of at least one resource block within the band portion for use by the at least one communication device (3-1, 3-2); and generate, from said obtained index and said information for identifying an allocation, control data for uniquely identifying a position of the allocation of at least one resource block, within said cell bandwidth; and wherein the transceiver is operable to signal the control data to the at least one communication device (3-1, 3-2), wherein the plurality of non-overlapping band portions comprises a plurality of equally sized band portions, wherein when the obtained index is an index of one of the equally sized band portions, the controller is further configured to generate the control data for uniquely identifying a position of the allocation of at least one resource block by jointly encoding the obtained index and the information for identifying an allocation to form jointly encoded control data, wherein the jointly encoded control data is derived using the following formula: JESRIV = RIV + 21 ∗ k where JESRIV is the jointly encoded control data; k is the obtained index; and RIV is the information for identifying an allocation and comprises a unique value representing an allocation of at least one resource block within band portion k.