Underlay network node and macro base station and methods therein for enabling avoidance of interference in a cell extension area associated with an uplink/downlink imbalance. The underlay network node is assumed to be associated with a cell area A, and a cell extension area B, where the cell extension area B has an uplink/downlink imbalance in relation to a neighboring base station and the network node. The method in the underlay network node involves serving a UE in both uplink and downlink when the UE is located in cell area A. The method further involves serving a UE only in the uplink when the UE is located in cell extension area B, thus enabling avoidance of interference related to communication of a UE located in said cell extension area B.