The technology in this application identifies a relay cell serviced by a relay radio node in a radio access network (RAN) of a cellular communications system in which there is a radio connection between the relay radio node and a donor radio base station. The donor radio base station is identified by a RAN donor radio base station cell identifier. A RAN relay cell identifier is determined that uniquely identifies the relay cell within the RAN, the RAN relay cell identifier including a relay cell identifier and a donor base station identifier. The RAN relay cell identifier is then provided or used as needed so that the relay radio node can transmit the RAN relay cell identifier to uniquely identify the relay cell to one or more radio terminals in the RAN.