User plane setup during 5g system to evolved packet system handover

Abstract

System comprising a mobility management entity, MME, a first Radio Access node, RAN (eNB) offering Long Term Evolution, LTE, access, and a second radio access node, RAN (gNB) offering New Radio, NR, access; a user entity, UE, supporting both Long Term Evolution, LTE, and New Radio, NR, Radio Access Technology, RAT.

1 . A Method for a Long-Term Evolution Radio Access Node, LTE RAN, E-UTRAN, (eNB) adapted for:
 engaging in a handover from a Next Generation RAN, denoted source RAN to said LTE RAN, denoted target RAN,   receiving a Handover Request message from a Mobility Management Entity, MME, and   allocating resources or bearers requested by a Mobility Management Entity, MME, even though said resources or said bearers are not included in a transparent container from the source RAN.   
     
     
         2 . A Method for a system comprising:
 a Long-Term Evolution Radio Access Node, LTE RAN, E-UTRAN (eNB),   a Next Generation Radio Access Node, RAN, denoted target RAN   an Access and Mobility Management Function, AMF,   a Mobility Management Entity, MME,   a Serving Gateway, SGW, and   a Visited User Plane Function, V-UPF,   the system being adapted for:
 the NG RAN NG, denoted source RAN, deciding that the UE should be handed over to the LTE RAN, denoted target RAN, and sending a Handover Required to the AMF, 
 the AMF determining from a ‘Target eNB Identifier’ IE that the type of handover is Handover to E-UTRAN, the AMF selecting an MME, and sending Nsmf_PDU Session_Context Request requests the V-SMF for each PDU Session associated with 3GPP access to provide SM Context that also includes mapped EPS Bearer Contexts, 
 the AMF receiving a Nsmf_PDU Session_Context Request response, 
 the AMF issuing a relocation request to the MME, 
 the MME and SGW engaging in create session request and response messaging, 
 the MME issuing a handover request to the LTE RAN, and 
 the LTE RAN allocating resources or bearers requested by MME even though said resources or said bearers are not included in a transparent container from the source RAN. 
   
     
     
         3 . The Method according to  claim 2 , wherein:
 the LTE RAN moreover
 not allocating a forwarding tunnel for the bearers not part of the source to target transparent container, and 
 including in target to source transparent container the bearers requested by source RAN and requested by core network. 
   
     
     
         4 . The Method according to  claim 2 , wherein:
 the Access and Mobility Management Function, AMF, adapted to perform issuing a Nmsf Packet Data Unit, PDU, Session Context request to a SMF, even for PDU sessions without user plane currently, that is, also for PDU sessions not included in a Handover Re-quired message from Next Generation, NG-Radio Access Node, RAN.   
     
     
         5 . A Method for an Access and Mobility Management Function, AMF, adapted to perform issuing a Nmsf Packet Data Unit, PDU, Session Context request to a SMF, even for PDU sessions without user plane currently, that is, also for PDU sessions not included in a Handover Required message from Next Generation, NG,—Radio Access Node, RAN. 
     
     
         6 . A Method for an AMF adapted for not applying indirect data forwarding for the PDU sessions that does not have user plane in Next Generation, NG-Radio Access Node, RAN previously. 
     
     
         7 . A Method for a next Generation—Radio Access Node, NG RAN (gNB) adapted to accept a handover command from an Access and Mobility Management Function, AMF even when a transparent container from a target RAN, such as eNB, includes more user plane for bearers than NG-RAN required, the NG-RAN moreover adapted for delivering the handover command to UE. 
     
     
         8 . A Method for a UE being adapted for correlating QoS flows that does not have user plane resource currently with EPS bearer IDs to be setup in the HO command. 
     
     
         9 . A Long-Term Evolution Radio Access Node, LTE RAN, EUTRAN, (eNB) having a radio interface (IF_M) and processing circuitry (PCU_M), the base station's pro-cessing circuitry adapted for:
 engaging in a handover from a Next Generation RAN, denoted source RAN to said LTE RAN, denoted target RAN,   receiving a Handover Request message from a Mobility Management Entity, MME, and   allocating resources or bearers requested by a Mobility Management Entity, MME, even though said resources or said bearers are not included in a transparent container from the source RAN.   
     
     
         10 . A System comprising
 a Long-Term Evolution Radio Access Node, LTE RAN, E-UTRAN (eNB),   a Next Generation Radio Access Node, RAN, denoted target RAN   an Access and Mobility Management Function, AMF,   a Mobility Management Entity, MME,   a Serving Gateway, SGW, and   a Visited User Plane Function, V-UPF,   the system being adapted for   the NG RAN NG, denoted source RAN, deciding that the UE should be handed over to the LTE RAN, denoted target RAN, and sending a Handover Required to the AMF,   the AMF determining from a ‘Target eNB Identifier’ IE that the type of handover is Handover to E-UTRAN, the AMF selecting an MME, and sending Nsmf_PDU Ses-sion_Context Request requests the V-SMF for each PDU Session associated with 3GPP access to provide SM Context that also includes mapped EPS Bearer Contexts,   the AMF receiving a Nsmf_PDU Session_Context Request response,   the AMF issuing a relocation request to the MME,   the MME and SGW engaging in create session request and response messaging,   the MME issuing a handover request to the LTE RAN, and   the LTE RAN allocating resources or bearers requested by MME even though said re-sources or said bearers are not included in a transparent container from the source RAN.   
     
     
         11 . An Access and Mobility Management Function, AMF, adapted to perform issuing a Nmsf Packet Data Unit, PDU, Session Context request to a SMF, even for PDU sessions without user plane currently, that is, also for PDU sessions not included in a Handover Required message from Next Generation, NG-Radio Access Node, RAN. 
     
     
         12 . A Next Generation Radio Access Node, RAN, NG-RAN (gNB) adapted to accept a handover command from an AMF even when a transparent container from a target RAN, such as an LTE RAN (eNB), includes more user plane for bearers than NG-RAN required, the NG-RAN moreover adapted for delivering the handover command to UE. 
     
     
         13 . A UE being adapted for correlating QoS flows that does not have user plane resource currently with EPS bearer IDs to be setup in the HO command.