A scheme for resource allocation for variable rate users in a packet-based radio communication system such as a UMTS TDD system is based on a representation (200) of the resource space organised orthogonally in 3 dimensions by codes, timeslots and frames. The representation (200) is searched to identify new resources that may be allocated and updated when new resources have been allocated. This scheme provides an efficient method for placing allocated resources into the system resource space while maintaining efficient packing, and provides the following advantages: allocations that result in different overall throughput rates can be made to users; efficient packing of allocated resources means that wasted resources is minimised; since the representation of the system resource space is bounded, the stored information at the resource allocator function (in the radio access network) can be minimized; allocations are only made based on the most current frame in the representation of the system resource space this reduces required complexity; and the maximum number of frames into the future over which resources can be allocated can be used to modify the shape of allocations.