A mobile node comprising: circuitry, which, in operation, configured to: connect to a master base station and to a secondary base station via a split bearer that is split between the master base station and the secondary base station in a Packet Data Convergence Protocol, PDCP, layer; determine whether a total buffer occupancy of the PDCP layer in the mobile node exceeds a threshold; and responsive to the total buffer occupancy exceeding the threshold, split the total buffer occupancy of the PDCP layer into both a first PDCP buffer occupancy value which is a first split ratio of data to be transmitted to the master base station and a second PDCP buffer occupancy value which is a second split ratio of data to be transmitted to the secondary base station; and a transmitter, which is coupled to the circuitry and which, in operation, is configured to transmit a first buffer status report based on the first PDCP buffer occupancy value to the master base station, and a second buffer status report based on the second PDCP buffer occupancy value to the secondary base station, characterized in that, the circuitry, responsive to the total buffer occupancy not exceeding the threshold, splits the total buffer occupancy of the PDCP layer based on a defined split ratio into a third PDCP buffer occupancy value of data to be transmitted to the master base station and a fourth PDCP buffer occupancy value of data to be transmitted to the secondary base station, the defined split ratio is configured such that one of the third and fourth PDCP buffer occupancy values is equal to the total buffer occupancy of the PDCP layer in the mobile node for the split bearer, and the other one of the third and fourth PDCP buffer occupancy values is equal to zero. circuitry, which, in operation, configured to: connect to a master base station and to a secondary base station via a split bearer that is split between the master base station and the secondary base station in a Packet Data Convergence Protocol, PDCP, layer; determine whether a total buffer occupancy of the PDCP layer in the mobile node exceeds a threshold; and responsive to the total buffer occupancy exceeding the threshold, split the total buffer occupancy of the PDCP layer into both a first PDCP buffer occupancy value which is a first split ratio of data to be transmitted to the master base station and a second PDCP buffer occupancy value which is a second split ratio of data to be transmitted to the secondary base station; and a transmitter, which is coupled to the circuitry and which, in operation, is configured to transmit a first buffer status report based on the first PDCP buffer occupancy value to the master base station, and a second buffer status report based on the second PDCP buffer occupancy value to the secondary base station, characterized in that, the circuitry, responsive to the total buffer occupancy not exceeding the threshold, splits the total buffer occupancy of the PDCP layer based on a defined split ratio into a third PDCP buffer occupancy value of data to be transmitted to the master base station and a fourth PDCP buffer occupancy value of data to be transmitted to the secondary base station, the defined split ratio is configured such that one of the third and fourth PDCP buffer occupancy values is equal to the total buffer occupancy of the PDCP layer in the mobile node for the split bearer, and the other one of the third and fourth PDCP buffer occupancy values is equal to zero.