A cellular radio access network is provided by a high altitude platform (HAP). The HAP has an antenna system defining a plurality of beams, such that the beams provide separate geographical coverage areas. The radio access network comprises a plurality of cells, each cell being associated with at least one of the plurality of beams. For each of the plurality of cells and/or each of the plurality of beams, a respective load is identified. A configuration is set, based on the loads for the plurality of cells and/or the loads for the plurality of beams, for one or more of: a total number of the plurality of cells; the associations between the plurality of cells and the plurality of beams; and a bandwidth and/or a power for each of the plurality of cells.