Telecommunications apparatus and methods for handling split radio bearers

A terminal device for use in a wireless telecommunications network which comprises a core network;

• base stations supported by the core network and each providing wireless connectivity within at least one base station cell where the cells are arranged into a master cell group under control of a master base station and a secondary cell group under control of a secondary base station;
• and the terminal device, wherein the terminal device comprises:
• circuitry configured to:
• communicate wirelessly with the base stations including by the use of a split radio bearer receivable at the secondary base station for splitting between the secondary base station and the master base station before delivery to the terminal device;
• and
• effect an alteration in data handling resources of the terminal device which are allocated for handling split ratio radio bearers received from the secondary base station in response to a reconfiguration message sent by the master base station to the terminal device in response to receipt by the master base station of a notification sent by the secondary base station following exhaustion of a supply of unique parameter sets used by the secondary base station in security ciphering of received split radio bearers, the notification requiring the master base station to alter data handling resources allocated for handling split radio bearers received from the secondary base station in one or both of the master base station and the terminal device.

A method for use in a wireless telecommunications network including a core network;

• base stations supported by the core network and each providing wireless connectivity within at least one base station cell where the cells are arranged into a master cell group under control of a master base station and a secondary cell group under control of a secondary base station, wherein in the secondary cell group one cell is designated as a primary secondary cell with responsibility for uplink control signalling in the secondary cell group;
• and a terminal device configured to communicate wirelessly with the base stations including by the use of a split radio bearer receivable at the secondary cell group via the primary secondary cell for splitting between the secondary base station and the roaster base station before delivery to the terminal device, the method comprising:
• in the event of a need to change the designation of the primary secondary cell to a different cell in the secondary cell group, the secondary base station sending a notification to the master base station of a requirement to alter data handling resources allocated for handling split radio bearers received from the secondary base station in one or both of the master base station and the terminal device;
• and
• the master base station, in response to the notification, operating to effect an alteration in the said data handling resources.

A terminal device for use in a wireless telecommunications network which comprises a core network;

• base stations supported by the core network and each providing wireless connectivity within at least one base station cell where the cells are arranged into a master cell group under control of a master base station and a secondary cell group under control of a secondary base station wherein in the secondary cell group one cell is designated as a primary secondary cell;
• and the terminal device, wherein the terminal device comprises:
• circuitry configured to:
• communicate wirelessly with the base stations including by the use of a split radio bearer receivable at the secondary cell group for splitting between the secondary base station and the master base station before delivery to the terminal device;
• and
• effect an alteration in data handling resources of the terminal device which are allocated for handling split ratio radio bearers received from the secondary base station in response to a reconfiguration message sent by the master base station to the terminal device in response to receipt by the master base station of a notification sent by the secondary base station when a need arises to change the designation of the primary secondary cell to a different cell in the secondary cell group, the notification requiring the master base station to alter data handling resources allocated for handling split radio bearers received from the secondary base station in one or both of the master base station and the terminal device.