Interworking between networks operating according to different radio access technologies

A network node for use in a first network that is operating according to a first radio access technology (RAT), the network node supporting a network interworking feature that enables and controls interworking between the first network and a network operating according to a second RAT, the network node controlling a first cell in the first network, the network node comprising:

• interface circuitry;
• and
• a processing circuit configured to:
• receive a handover message for a terminal device, the handover message indicating a request to handover the terminal device from a source base station to the network node;
• obtain access network selection information for use by the terminal device in performing one or both of access network selection and traffic steering after receiving the handover message for the terminal device, wherein the access network selection information was provided to the terminal device from the source base station or another base station;
• determine whether or not the terminal device should continue to use the access network selection information while the terminal device is being served by the target base station;
• and
• provide to the terminal device an indication that indicates one of:
• 1) that the target base station has determined that the terminal device should continue to use the access network selection information while the terminal device is being served by the target base station and 2) that the target base station has determined that the terminal device should not continue to use the access network selection information while the terminal device is being served by the target base station, wherein
• the source base station is configured to operate according to the first RAT, and
• the network node is configured to operate according to the first RAT.

A method in a source base station in a first network that is operating according to a first radio access technology (RAT), the method comprising:

• the source base station determining whether a handover message for a terminal served by the source base station should be sent to a target base station;
• the source base station, after determining that the handover message for the terminal should be sent to the target base station, providing to the target base station access network selection information for use by the terminal in performing one or both of access network selection and traffic steering;
• and
• as a result of determining that the handover message for the terminal should be sent to the target base station, the source base station sending to the target base station the handover message, wherein the handover message indicates a request to handover the terminal device from the source base station to the target base station, wherein
• the source base station is operating according to the first RAT, and
• the target base station is operating according to the first RAT.

A source base station for use in a first network that is operating according to a first radio access technology (RAT), the source base station supporting a network interworking feature that enables and controls interworking between the first network and a network operating according to a second RAT, the source base station comprising:

• interface circuitry;
• and
• a processing circuit configured to:
• determine whether a handover message for a terminal served by the source base station should be sent to a target base station;
• after determining that the handover message for the terminal should be sent to the target base station, provide to the target base station access network selection information for use by the terminal in performing one or both of access network selection and traffic steering;
• and
• send to the target base station the handover message as a result of determining that the handover message for the terminal should be sent to the target base station, wherein the handover message indicates a request to handover the terminal device from the source base station to the target base station, wherein
• the source base station is configured to operate according to the first RAT, and
• the target base station is configured to operate according to the first RAT.

A terminal device for use in a first network that is operating according to a first radio access technology (RAT), the terminal device supporting and operating according to a network interworking feature that enables and controls interworking between the first network and a network operating according to a second RAT, the terminal device comprising:

• transceiver circuitry;
• and
• a processing circuit configured to:
• employ the transceiver circuitry to send access network selection information for the terminal device to a network node controlling a first cell in the first network, the access network selection information having been previously used by the terminal device in another cell in the first network in performing one or both of access network selection and traffic steering;
• and
• determine whether the network node has provided to the terminal device an indication of the suitability of the access network selection information.