A macro base station of a wireless telecommunications network, wherein said macro base station defines a macro cell, said macro base station being provisioned to execute a method comprising: determining whether or not the macro base station is congested; determining whether or not a metro base station (22a, 22b, 22c) is uncongested, wherein said metro base station (22a, 22b, 22c) defines a metro cell located at least partially within the macro cell; and, if it is determined the macro base station is congested and that the metro base station is uncongested, then the method further includes: determining that an attempt to apply Cell Association Bias, CAB, to the metro cell may benefit network throughput and / or performance; determining an initial bias amount for use in connection with the CAB; determining whether to apply the CAB for the metro cell based on the initial bias amount, wherein if the initial bias amount exceeds a maximum bias amount then CAB is not applied by the macro base station, otherwise if the initial bias amount does not exceed the maximum bias amount then CAB is applied by the macro base station for the metro cell using the initial bias amount; wherein the initial amount is determined from the Radio Resource Control measurements reported to the macro base station from all the user equipments in a border condition with respect to the metro cell; and wherein the maximum bias amount which can be supported is taken as the difference between the transmission power of the macro cell and the transmission power of the metro cell. determining whether or not the macro base station is congested; determining whether or not a metro base station (22a, 22b, 22c) is uncongested, wherein said metro base station (22a, 22b, 22c) defines a metro cell located at least partially within the macro cell; and, if it is determined the macro base station is congested and that the metro base station is uncongested, then the method further includes: determining that an attempt to apply Cell Association Bias, CAB, to the metro cell may benefit network throughput and / or performance; determining an initial bias amount for use in connection with the CAB; determining whether to apply the CAB for the metro cell based on the initial bias amount, wherein if the initial bias amount exceeds a maximum bias amount then CAB is not applied by the macro base station, otherwise if the initial bias amount does not exceed the maximum bias amount then CAB is applied by the macro base station for the metro cell using the initial bias amount; determining that an attempt to apply Cell Association Bias, CAB, to the metro cell may benefit network throughput and / or performance; determining an initial bias amount for use in connection with the CAB; determining whether to apply the CAB for the metro cell based on the initial bias amount, wherein if the initial bias amount exceeds a maximum bias amount then CAB is not applied by the macro base station, otherwise if the initial bias amount does not exceed the maximum bias amount then CAB is applied by the macro base station for the metro cell using the initial bias amount; wherein the initial amount is determined from the Radio Resource Control measurements reported to the macro base station from all the user equipments in a border condition with respect to the metro cell; and wherein the maximum bias amount which can be supported is taken as the difference between the transmission power of the macro cell and the transmission power of the metro cell.