Handover of terminal between nodes supporting two rats

A source network infrastructure equipment in a wireless telecommunications system, the source network infrastructure equipment comprising:

• controller circuitry and transceiver circuitry configured to operate together to:
• establish that a terminal device should be handed over from the source network infrastructure equipment to a target network infrastructure equipment in the wireless telecommunications system, wherein
• the source network infrastructure equipment is operable to communicate with the terminal device in accordance with a first radio access technology and a second radio access technology different from the first radio access technology, and
• the target network infrastructure equipment is operable to communicate with the terminal device in accordance with the first radio access technology and is not operable to communicate with the terminal device in accordance with the second radio access technology;
• transmit, to the target network infrastructure equipment, a handover request message comprising an indication of a source radio resource configuration for communication between the source network infrastructure equipment and the terminal device, wherein the source radio resource configuration includes a first configuration of the first radio access technology for the terminal device with respect to the source network infrastructure equipment and a second configuration of the second radio access technology for the terminal device with respect to the source network infrastructure equipment;
• receive from the target network infrastructure equipment a handover request acknowledgement message comprising an indication of a target radio resource configuration for communications between the target network infrastructure equipment and the terminal device in accordance with only the first radio access technology;
• and
• transmit to the terminal device in response to reception of the handover request acknowledgement message, a radio resource configuration command message including the indication of the target radio resource configuration and an indication to release an entirety of the second configuration of the second radio access technology, wherein
• the source network infrastructure equipment is operable to communicate with the terminal device using a radio bearer supported by a first layer 2-protocol stack for communications in accordance with the first radio access technology and a second layer 2-protocol stack for communications in accordance with the second radio access technology,
• the first radio access technology is long term evolution (LTE) technology and the first configuration is an LTE configuration, and
• the second radio access technology is new radio (NR) technology and the second configuration is an NR configuration.

A terminal device, comprising:

• controller circuitry and transceiver circuitry configured to operate together to:
• establish that the terminal device is to be handed over from a source network infrastructure equipment in a wireless telecommunications system to a target network infrastructure equipment in the wireless telecommunications system, wherein
• the source network infrastructure equipment is operable to communicate with the terminal device in accordance with a first radio access technology and a second radio access technology different from the first radio access technology, and
• the target network infrastructure equipment is operable to communicate with the terminal device in accordance with the first radio access technology and is not operable to communicate with the terminal device in accordance with the second radio access technology;
• receive, from the source network infrastructure equipment, a radio resource configuration command message including an indication of a target radio resource configuration for communications between the target network infrastructure equipment and the terminal device in accordance with the first radio access technology, and an indication to release;
• and
• communicate with the at least one of the source network infrastructure equipment and the target network infrastructure equipment using a radio bearer supported by a first layer 2-protocol stack for communications in accordance with the first radio access technology and a second layer 2-protocol stack for communications in accordance with the second radio access technology, wherein
• the indication of the target radio resource configuration is based on the source network infrastructure equipment having sent a handover request message to the target network infrastructure equipment, the handover request message comprising an indication of a source radio resource configuration for communications between the source network infrastructure equipment and the terminal device,
• the source radio resource configuration includes a first configuration of the first radio access technology for the terminal device with respect to the source network infrastructure equipment, and a second configuration of the second radio access technology for the terminal device with respect to the source network infrastructure equipment,
• the indication to release indicates to release an entirety of the second configuration of the second radio access technology,
• the first radio access technology is long term evolution (LTE) technology and the first configuration is an LTE configuration, and
• the second radio access technology is new radio (NR) technology and the second configuration is an NR configuration.

A method of operating a target network infrastructure equipment in a wireless telecommunications system, the method comprising:

• receiving a handover request message from a source network infrastructure equipment in the wireless telecommunications system, wherein
• the source network infrastructure equipment is operable to communicate with the terminal device in accordance with a first radio access technology and a second radio access technology different from the first radio access technology,
• the target network infrastructure equipment is operable to communicate with the terminal device in accordance with the first radio access technology and is not operable to communicate with the terminal device in accordance with the second radio access technology,
• the handover request message comprises an indication of a source radio resource configuration for communications between the source network infrastructure equipment and the terminal device, and
• the source radio resource configuration includes a first configuration of the first radio access technology for the terminal device with respect to the source network infrastructure equipment and a second configuration of the second radio access technology for the terminal device with respect to the source network infrastructure equipment;
• and
• transmitting, to the source network infrastructure equipment, a handover request acknowledgement message comprising an indication of a target radio resource configuration for communications between the target network infrastructure equipment and the terminal device in accordance with only the first radio access technology, wherein
• the target network infrastructure equipment is operable to communicate with the terminal device using a radio bearer supported by a first layer 2-protocol stack for communications in accordance with the first radio access technology and a second layer 2-protocol stack for communications in accordance with the second radio access technology, wherein
• a radio resource configuration command message is transmitted from the source network infrastructure equipment transmits to the terminal device and in response to reception of the handover request acknowledge message, the radio resource configuration command message including the indication of the target radio resource configuration and an indication to release an entirety of the second configuration of the second radio access technology,
• the first radio access technology is long term evolution (LTE) technology and the first configuration is an LTE configuration, and
• the second radio access technology is new radio (NR) technology and the second configuration is an NR configuration.