A method performed by a base station for selecting a secondary carrier sector (B_x, B_y, B_z) of a second radio cell (Cell B) to be used by a user equipment when employing carrier aggregation, wherein the base station is serving a first radio cell (Cell A) as well as a second radio cell (Cell B), which second radio cell (Cell B) overlaps the first radio cell (Cell A), and wherein the base station is controlling multiple radio units each of which is serving a respective primary carrier sector (A_1, A_2, A_3, A_n) of the first radio cell (Cell A) and wherein the base station is also controlling multiple radio units each of which is serving a respective secondary carrier sector (B_x, B_y, B_z) of the second radio cell (Cell B), the method comprising: collecting information related to powers of all primary carrier sectors (A_1, A_2, A_3, A_n); based thereon comparing the powers of all primary carrier sectors (A_1, A_2, A_3, A_n) and determining which one of the primary carrier sectors (A_1, A2, A_3, A_n) has the highest power and which one of the primary carrier sectors (A_1, A_2, A_3, A_n) has the next highest power; comparing the highest power with a first threshold value; comparing a difference between the highest power and the next highest power with a second threshold value; responsive to the highest power being above the first threshold as well as the difference between the highest power and the next highest power being above the second threshold value ordering at least one selected user equipment to perform a Inter-Frequency Handover from a primary carrier (Carrier A) to a secondary carrier (Carrier B); in response thereto collecting information related to powers of all secondary carrier sectors (B_x, B_y, B_z) of the second radio cell (Cell B); based thereon comparing the powers of all secondary carrier sectors (B_x, B_y, B_z) and determining which one of the secondary carrier sectors (B_x, B_y, B_z) has the highest power; and selecting the secondary carrier sector with the highest power to become the secondary carrier sector (B_x, B_y, B_z) to be used. collecting information related to powers of all primary carrier sectors (A_1, A_2, A_3, A_n); based thereon comparing the powers of all primary carrier sectors (A_1, A_2, A_3, A_n) and determining which one of the primary carrier sectors (A_1, A2, A_3, A_n) has the highest power and which one of the primary carrier sectors (A_1, A_2, A_3, A_n) has the next highest power; comparing the highest power with a first threshold value; comparing a difference between the highest power and the next highest power with a second threshold value; responsive to the highest power being above the first threshold as well as the difference between the highest power and the next highest power being above the second threshold value ordering at least one selected user equipment to perform a Inter-Frequency Handover from a primary carrier (Carrier A) to a secondary carrier (Carrier B); in response thereto collecting information related to powers of all secondary carrier sectors (B_x, B_y, B_z) of the second radio cell (Cell B); based thereon comparing the powers of all secondary carrier sectors (B_x, B_y, B_z) and determining which one of the secondary carrier sectors (B_x, B_y, B_z) has the highest power; and selecting the secondary carrier sector with the highest power to become the secondary carrier sector (B_x, B_y, B_z) to be used.