A device for distributing a transmission power budget amongst a plurality of sub-bands in a transmission system, said device being adapted to: select one said sub-band for consideration, determine every possible combination of users assignable to said sub-band under consideration; assess each said possible combination of users assignable to the sub-band under consideration to select the channel gain value of the user in that combination having the highest channel gain, to determine a sub-band attenuation value proportional to the reciprocal of the square of said selected channel gain value; to apply a water filling algorithm across said selected sub-band and every sub-band selected previously using a floor for each said sub-band defined by the respective said sub-band attenuation value, to calculate a provisional power allocation from said water filling algorithm for said selected sub-band, and to calculate a performance metric with said provisional power attribution; and to attribute to said selected sub-band whichever said combination of users optimises said performance metric; said device being further adapted to then select a further said sub-band and to repeat said operations of: assess each said possible combination of users assignable to said sub-band under consideration; and attributing to said sub-band whichever said combination of users optimises said performance metric; until all said sub-bands have been considered, and to calculate a final power allocation for each said sub-band from the last iteration of the water filling algorithm corresponding to the combination of users selected for each said sub-band. select one said sub-band for consideration, determine every possible combination of users assignable to said sub-band under consideration; assess each said possible combination of users assignable to the sub-band under consideration to select the channel gain value of the user in that combination having the highest channel gain, to determine a sub-band attenuation value proportional to the reciprocal of the square of said selected channel gain value; to apply a water filling algorithm across said selected sub-band and every sub-band selected previously using a floor for each said sub-band defined by the respective said sub-band attenuation value, to calculate a provisional power allocation from said water filling algorithm for said selected sub-band, and to calculate a performance metric with said provisional power attribution; and to attribute to said selected sub-band whichever said combination of users optimises said performance metric; said device being further adapted to then select a further said sub-band and to repeat said operations of: assess each said possible combination of users assignable to said sub-band under consideration; and attributing to said sub-band whichever said combination of users optimises said performance metric; until all said sub-bands have been considered, and to calculate a final power allocation for each said sub-band from the last iteration of the water filling algorithm corresponding to the combination of users selected for each said sub-band. assess each said possible combination of users assignable to said sub-band under consideration; and attributing to said sub-band whichever said combination of users optimises said performance metric; until all said sub-bands have been considered, and to calculate a final power allocation for each said sub-band from the last iteration of the water filling algorithm corresponding to the combination of users selected for each said sub-band.