A method for configuring a reference signal performed by a first node in a radio relay system, the radio relay system including a base station, a first user equipment, UE, served by the base station, relay nodes, and second UEs served by the relay nodes, o wherein: ▪ the first node is the base station, the first node is connected to the first UE by an access link, ▪ a second node, being a relay node among the relay nodes, is connected to the first node by a wireless backhaul link and to one of the second UEs by an access link, and ▪ a third node, being a further relay node among the relay nodes, is connected to the second node by a wireless backhaul link and to another one of the second UEs by an access link, o wherein the first node is an upper-level node of the second node, wherein an upper level node of a node provides a service to said node, wherein the method comprises the steps of: a.) receiving (step 401) first information from the second node, wherein the first information comprises beam information of beams used by the backhaul link between the second node and the third node; and b.) sending (step 402) configuration information to the second node, wherein the configuration information is used to indicate configuration information of a reference signal received or sent by the second node on a target beam, and the target beam is at least one of those beams used by the backhaul link between the second node and the third node, wherein the first information further comprises information about a further reference signal of at least one beam among those beams used by the backhaul link between the second node and the third node, wherein the configuration information of the reference signal received or sent by the second node on the target beam comprises information indicating that there is a quasi co-location, QCL, relationship between the reference signal received or sent by the second node on the target beam and the further reference signal of the at least one beam. o wherein: ▪ the first node is the base station, the first node is connected to the first UE by an access link, ▪ a second node, being a relay node among the relay nodes, is connected to the first node by a wireless backhaul link and to one of the second UEs by an access link, and ▪ a third node, being a further relay node among the relay nodes, is connected to the second node by a wireless backhaul link and to another one of the second UEs by an access link, ▪ the first node is the base station, the first node is connected to the first UE by an access link, ▪ a second node, being a relay node among the relay nodes, is connected to the first node by a wireless backhaul link and to one of the second UEs by an access link, and ▪ a third node, being a further relay node among the relay nodes, is connected to the second node by a wireless backhaul link and to another one of the second UEs by an access link, o wherein the first node is an upper-level node of the second node, wherein an upper level node of a node provides a service to said node, a.) receiving (step 401) first information from the second node, wherein the first information comprises beam information of beams used by the backhaul link between the second node and the third node; and b.) sending (step 402) configuration information to the second node, wherein the configuration information is used to indicate configuration information of a reference signal received or sent by the second node on a target beam, and the target beam is at least one of those beams used by the backhaul link between the second node and the third node, wherein the first information further comprises information about a further reference signal of at least one beam among those beams used by the backhaul link between the second node and the third node, wherein the configuration information of the reference signal received or sent by the second node on the target beam comprises information indicating that there is a quasi co-location, QCL, relationship between the reference signal received or sent by the second node on the target beam and the further reference signal of the at least one beam.