Abstract: A method of operating a mobile telecommunications system having a base station, a plurality of users and a plurality of spectral resource blocks, some of which are not allocated to users. The method includes, (a) for each user, assigning a score to each resource block based on the energy efficiency with which the user can use the resource block, and determining which of the plurality of resource blocks is favored, i.e. has a score indicating that it will be the most energy efficient for the user. For each user, either (b) if the user's favored resource block is not allocated, and is not favored by any other user, that resource block is allocated to that user; or (c) in the event that the same resource block is favored by more than one user, it is allocated to the user who will use it with the greatest energy efficiency.