One method for controlling operation of a repeater in radio communication system comprises determination whether operation of a node in the radio communication system benefits from assistance of a repeater and transmitting, from the node in the radio communication system, a radio signal to the repeater being indicative of an order to promptly activate the repeater if the benefit exists. One complementary method for controlling operation of a repeater in radio communication system comprises detection (252), in the repeater, of a radio signal being indicative of an order to activate the repeater. Amplification in the repeater is activated (254) as a response to such a detected radio signal and uplink traffic from a user terminal being located in a vicinity of the repeater and/or downlink traffic to the user terminal is amplified (256). A repeater, a node, a user terminal and a system operating according to the method are presented.