A method of conveying an allocation of radio resources on a radio channel for communicating data between a base station and a terminal device in a wireless telecommunications system, wherein the radiochannel spans a channel frequency bandwidth divided into frequency resource units which may be selectively allocated for communicating data between the base station and the terminal device. The method comprises, at the base station, selecting a combination of resource units for communicating the data between the base station and the terminal device from among a predefined set of allowable combinations of resource units, wherein the allowable combinations of resource units include non-contiguous combinations of resource units and the number of allowable combinations of resource units is smaller than the total number of combinations of resource units; and conveying, to the terminal device, an indication of the selected combination of resource units.