A mobile communication system sub-network comprising a macrocell base station (DgNB) and a plurality of small cell base stations (SC1; SC2.1-SC3.3), the plurality of small cell base stations being in wireless communication with the macrocell base station, wherein each small cell base station is either in direct connection with the macrocell base station or is in connection with the macrocell base station via one or more other small cell base stations, wherein the macrocell base station is arranged to configure a user equipment, UE, device (UE1-UE5) having a radio resource control, RRC, connection to the macrocell base station to perform autonomous switching between small cell base stations using candidate small cell base station information, and wherein each of the small cell base stations is arranged to receive configuration information from the macrocell base station and to configure the small cell base station using the configuration information to receive data from the UE device on a radio bearer, to determine a radio bearer identifier uniquely identifying the radio bearer using the small cell base station configuration information, and to forward the data together with the determined radio bearer identifier to another small cell base station or to the macrocell base station via a wireless backhaul link, the small cell base station configuration information received from the macrocell base station comprising a UE device identifier identifying a UE device configured by the macrocell base station with candidate small cell base station information relating to the small cell base stations, and one or more radio bearer identifiers uniquely identifying one or more radio bearers of the UE device. wherein the macrocell base station is arranged to configure a user equipment, UE, device (UE1-UE5) having a radio resource control, RRC, connection to the macrocell base station to perform autonomous switching between small cell base stations using candidate small cell base station information, and wherein each of the small cell base stations is arranged to receive configuration information from the macrocell base station and to configure the small cell base station using the configuration information to receive data from the UE device on a radio bearer, to determine a radio bearer identifier uniquely identifying the radio bearer using the small cell base station configuration information, and to forward the data together with the determined radio bearer identifier to another small cell base station or to the macrocell base station via a wireless backhaul link, the small cell base station configuration information received from the macrocell base station comprising a UE device identifier identifying a UE device configured by the macrocell base station with candidate small cell base station information relating to the small cell base stations, and one or more radio bearer identifiers uniquely identifying one or more radio bearers of the UE device. a UE device identifier identifying a UE device configured by the macrocell base station with candidate small cell base station information relating to the small cell base stations, and one or more radio bearer identifiers uniquely identifying one or more radio bearers of the UE device.