Methods and apparatus for optimized inter-system handover
Transport information of a second communication system is allocated to at least one radio access bearer between a terminal device and a first packet core serving device of a first communication system. Information about the at least one allocated tunnel endpoint is signalled to a network access device of the first communication system, and data received from the first packet core serving device of the first communication system at one of the at least one allocated tunnel endpoints and data received from a second packet core serving device of the second communication system is forwarded to the terminal device during an inter-system handover.
1 . An target base station of a communication system, the target base station comprising:
at least one processor; and
at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the target base station to perform:
allocating transport information of the communication system to at least one radio access bearer between a terminal device and a first packet core serving device of a source communication system;
signalling the allocated transport information to a network access device of the source communication system;
forwarding (a) first data received from the first packet core serving device of the source communication system in accordance with the allocated transport information and (b) second data received from a second packet core serving device of the communication system to the terminal device during an inter-system handover; and
determining a dual-connectivity capability required for the inter-system handover based on a response received from the network access device of the source communication system.
2 . The target base station of claim 1 , wherein the at least one memory and computer program code are further configured to with the at least one processor, cause the target base station to infer the dual-connectivity capability from at least one of the transport information or a continuation flag provided in the response received from the network access device of the source communication system.
3 . The target base station of claim 1 , wherein the response is an addition request message of an addition or modification procedure for adding a secondary network access device to the terminal device.
4 . The target base station of claim 1 , wherein the response is a handover request message.
5 . The target base station of claim 1 where the at least one memory and computer program code are configured to, with the at least one processor, cause the target base station to signal the transport information in a handover request message.
6 . The target base station of claim 1 where the at least one memory and computer program code are configured to, with the at least one processor, cause the target base station to signal the transport information in a response to an addition request message of an addition or modification procedure for adding a secondary network access device to the terminal device, the addition request message comprising information about the at least one radio access bearer between the terminal device and the first packet core serving device of the source communication system.
7 . The target base station of claim 1 where the at least one memory and computer program code are further configured to, with the at least one processor, cause the target base station to manage a transition from old data coming from the first packet core serving device of the source communication system to new data coming from the second packet core serving device of the communication system.
8 . The target base station of claim 1 where the at least one memory and computer program code are further configured to, with the at least one processor, cause the target base station to set a network access device of the communication system into a state of a secondary network access device for the terminal device, wherein the network access device of the source communication system is a master network access device of the terminal device.
9 . An apparatus comprising:
at least one processor; and
at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform:
receiving transport information from a network access device of a communication system of a target base station;
signalling the received transport information to a packet core serving device of a source communication system for use in an inter-system handover from the source communication system to the communication system of the target base station; and
signalling an indication about a dual-connectivity status towards the network access device of the communication system of the target base station.
10 . The target base station according to claim 1 , wherein the first data is forwarded without forwarding the first data between a source base station and the target base station.
11 . The apparatus of claim 9 where the at least one memory and computer program code are configured to, with the at least one processor, cause the apparatus to receive the transport information from the network access device of the communication system of the target base station in a handover request message, and to signal the indication about the dual-connectivity status to the network access device of the communication system of the target base station by an addition request message of an addition or modification procedure for adding the network access device of the communication system as a secondary network access device to a terminal device.
12 . The apparatus of claim 9 where the at least one memory and computer program code are configured to, with the at least one processor, cause the apparatus to receive the transport information from the network access device of the communication system of the target base station in a response to an addition request message of an addition or modification procedure for adding the network access device of the communication system of the target base station as a secondary network access device to a terminal device, and to signal the indication about the dual-connectivity status to the network access device of the communication system of the target base station in a handover required message.
13 . The apparatus of claim 11 where the at least one memory and computer program code are configured to, with the at least one processor, cause the apparatus to signal the indication about the dual-connectivity status by adding at least one of the transport information or a continuation flag.
14 . The apparatus of claim 9 where the at least one memory and computer program code are configured to, with the at least one processor, cause the apparatus to signal the received transport information to the packet core serving device of the source communication system in a radio access bearer modification indication message.
15 . The apparatus of claim 9 where the at least one memory and computer program code are configured to, with the at least one processor, cause the apparatus to signal the received transport information to the packet core serving device of the source communication system in a handover request acknowledge message.
16 . The apparatus of claim 9 where the source communication system is an evolved packet system and the communication system of the target base station is a 5th generation system.
17 . The apparatus of claim 9 where the transport information comprises information about a transport address and a tunnel endpoint.
18 . The apparatus of claim 9 where the transport information is signalled in a transparent container.
19 . A method comprising:
allocating transport information of a communication system of a target base station to at least one radio access bearer between a terminal device and a first packet core serving device of a source communication system;
signalling the allocated transport information to a network access device of the source communication system;
forwarding (a) first data received from the first packet core serving device of the source communication system in accordance with the allocated transport information and (b) second data received from a second packet core serving device of the communication system of a target base station to the terminal device during an inter-system handover; and
determining a dual-connectivity capability required for the inter-system handover based on a response received from the network access device of the source communication system.
20 . A method comprising:
receiving transport information from a network access device of a communication system of a target base station;
signalling the received transport information to a packet core serving device of a source communication system for use in an inter-system handover from the source communication system to the communication system of the target base station; and
signaling an indication about a dual-connectivity status towards the network access device of the communication system of the target base station.
21 . The method according to claim 19 , wherein the first data is forwarded without forwarding the first data between a source base station and a target base station.