A network node and a method performed thereby for controlling operation of a low power node are provided. The network node and the low power node are operable in a wireless communication network, wherein the low power node has at least two modes of operation, an active mode where the low power node is in full operation, and a passive mode where the low power node is discoverable by wireless devices in the network but not available for initial access or incoming handovers. The method comprises receiving (210) a measurement report from at least one wireless device, the measurement report comprising a measurement related to the low power node; and determining (220) the operation mode of the low power node based on the received measurement report. The method further comprises when the current operation mode of the low power node is passive and the determined operation mode is active, changing (230) the operation mode of the low power node to active mode.