A system, method, and devices for communicating from a primary station to a plurality of secondary station are disclosed. The method includes the step of allocating a resource to the secondary stations over time on the basis of a hash function such that for a particular subframe the control channel elements to be searched in the search space are assigned at an equal probability for different secondary stations, and such that for any pair of subframes, the number of secondary station identifiers which can generate output values i and j is approximately the same for any values of i and j.