Radio communication system, base station apparatus, and radio terminal

A base station apparatus comprising:

• a memory;
• and
• at least one hardware processer coupled to the memory and configured to execute modules comprising a communication controller configured to control dual connectivity involving a bearer split in which a network bearer between a radio terminal and a core network is split over the base station apparatus and a neighbor base station, wherein
• the communication controller is further configured to transmit, to the radio terminal, first control information that relates to an access stratum,
• the first control information includes Layer-2 configuration information applied to a procedure for generating, in the radio terminal, a first Medium Access Control Protocol Data Unit (MAC PDU) for uplink transmission in a first cell managed by the base station apparatus and a second MAC PDU for uplink transmission in a second cell managed by the neighbor base station, and
• the Layer-2 configuration information includes information indicating that the generation of the second MAC PDU is prioritized higher than the generation of the first MAC PDU to transmit uplink data for a logical channel of the network bearer.

A radio terminal comprising:

• a memory;
• and
• at least one hardware processor coupled to the memory and configured to execute modules including a communication controller configured to control dual connectivity involving a bearer split in which a network bearer between the radio terminal and a core network is split over a first base station and a second base station, wherein
• the communication controller is further configured to receive, from the first or second base station, first control information that relates to an access stratum and is necessary for the dual connectivity involving the bearer split, determine whether the bearer split is required based on the first control information, and control communication employing the dual connectivity in accordance with the first control information,
• the first control information includes Layer-2 configuration information applied to a procedure for generating, in the radio terminal, a first Medium Access Control Protocol Data Unit (MAC PDU) for uplink transmission in a first cell managed by the first base station and a second MAC PDU for uplink transmission in a second cell managed by the second base station, and
• the Layer-2 configuration information includes information indicating that the generation of the second MAC PDU is prioritized higher than the generation of the first MAC PDU to transmit uplink data for a logical channel of the network bearer.

A control method that is performed in a radio terminal, the control method comprising:

• receiving, from a first base station or a second base station, first control information that relates to an access stratum and is necessary for dual connectivity involving a bearer split in which a network bearer between the radio terminal and a core network is split over the first base station and the second base station;
• and
• determining whether the bearer split is required based on the first control information and controlling communication employing the dual connectivity in accordance with the first control information, wherein
• the first control information includes Layer-2 configuration information applied to a procedure for generating, in the radio terminal, a first Medium Access Control Protocol Data Unit (MAC PDU) for uplink transmission in a first cell managed by the first base station and a second MAC PDU for uplink transmission in a second cell managed by the second base station, and
• the Layer-2 configuration information includes information indicating that the generation of the second MAC PDU is prioritized higher than the generation of the first MAC PDU to transmit uplink data for a logical channel of the network bearer.