A spectrum management server, comprising: a communications interface over which communications with a hub radio device are made, wherein spectrum access requests for a spoke radio device are received at the spectrum management server by way of the hub radio device; and a processor characterised in that the processor is adapted to execute logical instructions to generate generic channel access credentials used by the spoke radio device to wirelessly communicate with the hub radio device before specific channel access credentials are supplied to the spoke radio device, the logical instructions configure the spectrum management server to: determine a coverage area of the hub radio device and determine sub-regions of the coverage area; logically overlap the coverage area with pixels of known geographic location and size; determine, for each pixel, a maximum transmit power level; identify a lowest maximum transmit power level for all pixels overlapping the sub-region of the coverage area; determine a generic access transmit power limit for each sub-region of the coverage area based at least in part on the identifying a lowest maximum transmit power level, wherein the generic access transmit power is determined for one or more channels on which the hub radio device has specific channel access credentials to engage in wireless communications; and transmit the generic access transmit power limit for each sub-region and channel combination to the hub radio device. a communications interface over which communications with a hub radio device are made, wherein spectrum access requests for a spoke radio device are received at the spectrum management server by way of the hub radio device; and a processor characterised in that the processor is adapted to execute logical instructions to generate generic channel access credentials used by the spoke radio device to wirelessly communicate with the hub radio device before specific channel access credentials are supplied to the spoke radio device, the logical instructions configure the spectrum management server to: determine a coverage area of the hub radio device and determine sub-regions of the coverage area; logically overlap the coverage area with pixels of known geographic location and size; determine, for each pixel, a maximum transmit power level; identify a lowest maximum transmit power level for all pixels overlapping the sub-region of the coverage area; determine a generic access transmit power limit for each sub-region of the coverage area based at least in part on the identifying a lowest maximum transmit power level, wherein the generic access transmit power is determined for one or more channels on which the hub radio device has specific channel access credentials to engage in wireless communications; and transmit the generic access transmit power limit for each sub-region and channel combination to the hub radio device. determine a coverage area of the hub radio device and determine sub-regions of the coverage area; logically overlap the coverage area with pixels of known geographic location and size; determine, for each pixel, a maximum transmit power level; identify a lowest maximum transmit power level for all pixels overlapping the sub-region of the coverage area; determine a generic access transmit power limit for each sub-region of the coverage area based at least in part on the identifying a lowest maximum transmit power level, wherein the generic access transmit power is determined for one or more channels on which the hub radio device has specific channel access credentials to engage in wireless communications; and transmit the generic access transmit power limit for each sub-region and channel combination to the hub radio device.