WO2021111414A1 - Rétroaction d'ue epsfb au niveau d'un vowlan en vue d'un transfert de session 3gpp - Google Patents

Rétroaction d'ue epsfb au niveau d'un vowlan en vue d'un transfert de session 3gpp Download PDF

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Publication number
WO2021111414A1
WO2021111414A1 PCT/IB2020/061543 IB2020061543W WO2021111414A1 WO 2021111414 A1 WO2021111414 A1 WO 2021111414A1 IB 2020061543 W IB2020061543 W IB 2020061543W WO 2021111414 A1 WO2021111414 A1 WO 2021111414A1
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WIPO (PCT)
Prior art keywords
cellular
access network
wireless device
ims
cellular system
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PCT/IB2020/061543
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English (en)
Inventor
George Foti
Ralf Keller
Juying GAN
Chunbo Wang
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Telefonaktiebolaget Lm Ericsson (Publ)
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Publication of WO2021111414A1 publication Critical patent/WO2021111414A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/14—Reselecting a network or an air interface
    • H04W36/144—Reselecting a network or an air interface over a different radio air interface technology
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H04W36/0022—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies
    • H04W36/00224—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB]
    • H04W36/00226—Control or signalling for completing the hand-off for data sessions of end-to-end connection for transferring data sessions between adjacent core network technologies between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB] wherein the core network technologies comprise IP multimedia system [IMS], e.g. single radio voice call continuity [SRVCC]

Definitions

  • the present disclosure relates to handover of a voice over non-cellular access (e.g., a Voice over Wireless Local Area Network (VoWLAN)) established Internet Protocol (IP) Multimedia Subsystem (IMS) session to a cellular radio access network (e.g., a Third Generation Partnership Project (3GPP) Next Generation Radio Access Network (NG-RAN)).
  • VoIP Voice over Wireless Local Area Network
  • IP Internet Protocol
  • IMS Internet Multimedia Subsystem
  • NG-RAN Next Generation Radio Access Network
  • IP Internet Protocol
  • IMS Internet Multimedia Subsystem
  • WLAN Wireless Local Area Network
  • EPC Evolved Packet Core
  • ePDG evolved Packet Data Gateway
  • UE User Equipment
  • 5GS Fifth Generation System
  • NR Fifth Generation
  • PDU Protocol Data Unit
  • EPS Evolved Packet System
  • FB Voice over NR
  • FIG. 4.13.6.X-1 Transfer of PDU session used for IMS voice from non-3GPP access to 5GS
  • the UE has an ongoing IMS voice session via non-3GPP access using ePDG or N3IWF, and the session is transferred to NG-RAN, depending on the selected RAT in 5GS (NR or E-UTRA), and the support of EPS/inter- RAT fallback in NG-RAN, either the IMS voice session continues over NG-RAN (E-UTRA) or EPS/inter-RAT fallback is triggered.
  • 5GS NR or E-UTRA
  • Steps 1, 2 and 3 apply to either of the above two cases.
  • UE has ongoing IMS voice session via non-3GPP access using ePDG or N3IWF. UE is triggered to move to 3GPP access and camps in NG-RAN.
  • the UE shall initiate Registration procedure as defined in clause
  • UE initiates PDU session establishment for the PDU session used for IMS voice service in order to initiatehandover from EPC/ePDG to 5GS as defined in clause 4.11.4.1 step 2 or to initiate handover from N3IWF to 3GPP access in 5GC in step 2 of clauses 4.9.2.1 and 4.9.2.3.
  • the SMF accepts the successful PDU session transfer to the UE in NAS.
  • NG-RAN may decide to trigger EPS or inter-RAT fallback, taking into account UE capabilities, indication from AMF that "Redirection for EPS fallback for voice is possible" (received as part of initial context setup as defined in TS 38.413 [10]), network configuration (e.g. N26 availability configuration) and radio conditions.
  • NG-RAN may initiate measurement report solicitation from the UE including E-UTRA as target.
  • NG-RAN responds indicating rejection to set up the QoS flow for IMS voice received in step 3 towards the PGW-C+SMF (or H-SMF+PGW-C via V-SMF, in case of roaming scenario) via AMF with and indication that mobility due to fallback for IMS voice is ongoing.
  • the PGW-C+SMF executes the release of resources in non-3GPP AN as specified in clause 4.11.4.1 and clauses 4.9.2.1 and 4.9.2.3.
  • the UE can be informed of whether IMS voice over Packet Switched (PS) session is supported only through EPS-fallback or Radio Access Technology (RAT)- fallback from Fifth Generation Core (5GC) to UE. More specifically, the UE can be told at 5G System (5GS) registration that native voice over NR is not supported. This is documented in 3GPP CR S2-1911903, an excerpt of which is reproduced below (additions made in the CR are underlined).
  • PS Packet Switched
  • RAT Radio Access Technology
  • the serving PLMN AMF shall send an indication toward the UE during the Registration procedure over 3GPP access to indicate if an IMS voice over PS session is supported or not supported in 3GPP access and non-3GPP access.
  • a UE with "IMS voice over PS" voice capability over 3GPP access should take this indication into account when performing voice domain selection, as described in clause 5.16.3.5.
  • the serving PLMN AMF may only indicate IMS voice over PS session supported over 3GPP access in one of the following cases:
  • the network or the UE are not able to support IMS voice over PS session over NR connected to 5GC, but is able for one of the following:
  • the network and the UE are able to support IMS voice over PS session over E-UTRA connected to 5GC, and the NG-RAN supports a handover or redirection to E-UTRA connected to 5GC for this UE at QoS Flow establishment for IMS voice;
  • the UE supports handover to EPS
  • the EPS supports IMS voice
  • the NG-RAN supports a handover to EPS for this UE at QoS Flow establishment for IMS voice
  • the UE supports redirection to EPS
  • the EPS supports IMS voice
  • the NG-RAN supports redirection to EPS for this UE at QoS Flow establishment for IMS voice.
  • the network is not able to provide a successful IMS voice over PS session over E-UTRA connected to 5GC, but is able for one of the following:
  • the UE supports handover to EPS
  • the EPS supports IMS voice
  • the NG-RAN supports a handover to EPS for this UE at QoS Flow establishment for IMS voice
  • the UE supports redirection to EPS
  • the EPS supports IMS voice
  • the NG-RAN supports redirection to EPS for this UE at QoS Flow establishment for IMS voice.
  • the serving PLMN provides this indication based e.g. on local policy, UE capabilities, HPLMN, whether IP address preservation is possible, whether NG-RAN to UTRAN SRVCC is supported and how extended NG-RAN coverage is, and the Voice Support Match Indicator from the NG-RAN (see TS 23.502 [3] clause 4.2.8a).
  • the AMF in serving PLMN shall indicate that IMS voice over PS is supported only if the serving PLMN has a roaming agreement that covers support of IMS voice with the HPLMN. This indication is per Registration Area.
  • the serving PLMN AMF shall also send an indication to the UE during the Registration procedure over 3GPP access to indicate if an IMS voice over PS session is only supported through EPS-fallback or RAT-fallback.
  • the UE can also be told at 5GS registration that EPS or RAT Fallback is supported. This is not documented, but has been discussed already in 3GPP.
  • the IMS layer (application layer) in the UE may prematurely tear down the IMS session during the EPS FB procedure.
  • systems and methods for preventing such premature tear down of the IMS session during the EPS FB procedure are disclosed.
  • a method of operation of a wireless device to perform handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network comprises detecting a trigger for handover of an IMS session used for IMS voice from a non- cellular access network to a cellular access network. The method further comprises, upon detecting the trigger, initiating handover of the IMS session used for IMS voice from the non-cellular access network to a cellular access network for a first cellular system.
  • IP Internet Protocol
  • IMS Internet Multimedia Subsystem
  • the method further comprises receiving, from the cellular access network, information that informs the wireless device that fallback from the first cellular system to a second cellular system is ongoing for the IMS session.
  • the method further comprises storing information that indicates that fallback from the first cellular system to the second cellular system is supported in a registration area in which the wireless device is currently located within the cellular access network.
  • the cellular access network is a Next Generation Radio Access Network (NG-RAN).
  • the first cellular system is a Fifth Generation (5G) System (5GS).
  • the second cellular system is an Evolved Packet System (EPS).
  • NG-RAN Next Generation Radio Access Network
  • EPS Evolved Packet System
  • the method further comprises communicating with the cellular access network for fallback from the first cellular system to the second cellular system.
  • the method further comprises, at a subsequent time, in order to perform handover of a second IMS session used for IMS voice from a non- cellular access network to a cellular access network while the wireless device is in the same registration area within the cellular access network, detecting a trigger for handover of the second IMS session used for IMS voice from a non-cellular access network to the cellular access network.
  • the method further comprises, upon detecting the trigger for handover of the second IMS session, determining, based on the stored information, that the wireless device is aware that fallback from the first cellular system to the second cellular system is supported in the registration area in which the wireless device is located at the subsequent time.
  • the method further comprises, upon determining that the wireless device is aware that fallback from the first cellular system to the second cellular system is supported in the registration area, initiating a handover of the IMS session used for IMS voice from the non-cellular access network to the second cellular system.
  • the first cellular communications system comprises one or more base stations in the cellular access network that support a first Radio Access Technology (RAT) and a first core network of the first cellular system
  • the second cellular system comprises one or more base stations in the cellular access network that support a second RAT and a core network of the second cellular system.
  • RAT Radio Access Technology
  • Corresponding embodiments of a wireless device are also disclosed.
  • a wireless device for performing handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network is adapted to detect a trigger for handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network.
  • the wireless device is further adapted to, upon detecting the trigger, initiate handover of the IMS session used for IMS voice from the non-cellular access network to a cellular access network for a first cellular system.
  • the wireless device is further adapted to receive, from the cellular access network, information that informs the wireless device that fallback from the first cellular system to a second cellular system is ongoing for the IMS session.
  • the wireless device is further adapted to store information that indicates that fallback from the first cellular system to the second cellular system is supported in a registration area in which the wireless device is currently located within the cellular access network.
  • a wireless device for performing handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network comprises one or more transmitters, one or more receivers, and processing circuitry associated with the one or more transmitters and the one or more receivers.
  • the processing circuitry is configured to cause the wireless device to detect a trigger for handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network.
  • the processing circuitry is further configured to cause the wireless device to, upon detecting the trigger, initiate handover of the IMS session used for IMS voice from the non-cellular access network to a cellular access network for a first cellular system.
  • the processing circuitry is further configured to cause the wireless device to receive, from the cellular access network, information that informs the wireless device that fallback from the first cellular system to a second cellular system is ongoing for the IMS session.
  • the processing circuitry is further configured to cause the wireless device to store information that indicates that fallback from the first cellular system to the second cellular system is supported in a registration area in which the wireless device is currently located within the cellular access network.
  • a method of operation of a wireless device to perform handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network comprises detecting a trigger for handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network. The method further comprises, upon detecting the trigger, determining that fallback from a first cellular system to a second cellular system is supported in a current registration area of the wireless device within the cellular access network.
  • the method further comprises, upon determining that the wireless device is aware that fallback from the first cellular system to the second cellular system is supported in the current registration area of the wireless device within the cellular access network, initiating a handover of the IMS session used for IMS voice from the non-cellular access network to the second cellular system.
  • the first cellular communications system comprises one or more base stations in the cellular access network that support a first RAT and a first core network of the first cellular system
  • the second cellular system comprises one or more base stations in the cellular access network that support a second RAT and a second core network of the second cellular system.
  • the cellular access network is a NG-RAN.
  • the first cellular system is a 5GS.
  • the second cellular system is an EPS.
  • a wireless device for performing handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network is adapted to detect a trigger for handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network.
  • the wireless device is further adapted to, upon detecting the trigger, determine that fallback from a first cellular system to a second cellular system is supported in a current registration area of the wireless device within the cellular access network.
  • a wireless device for performing handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network comprises one or more transmitters, one or more receivers, and processing circuitry associated with the one or more transmitters and the one or more receivers.
  • the processing circuitry is configured to cause the wireless device to detect a trigger for handover of an IMS session used for IMS voice from a non-cellular access network to a cellular access network.
  • the processing circuitry is further configured to cause the wireless device to, upon detecting the trigger, determine that fallback from a first cellular system to a second cellular system is supported in a current registration area of the wireless device within the cellular access network.
  • the processing circuitry is further configured to cause the wireless device to, upon determining that the wireless device is aware that fallback from the first cellular system to the second cellular system is supported in the current registration area of the wireless device within the cellular access network, initiate a handover of the IMS session used for IMS voice from the non- cellular access network to the second cellular system.
  • a method of operation of a radio access node in a cellular radio access network to perform handover of an IMS session used for IMS voice for a wireless device from a non-cellular access network to a cellular access network comprises receiving, from the wireless device, a message that initiates handover of an IMS session used for IMS voice for the wireless device from a non-cellular access network to a cellular access network and sending, to the wireless device, information that informs the wireless device that fallback from a first cellular system to a second cellular system or from a first RAT (to a second RAT is ongoing for the IMS session.
  • the method further comprises communicating with the wireless device and one or more other network nodes to provide fallback for the IMS session from the first cellular system to the second cellular system or from the first RAT to the second RAT.
  • the cellular access network is a NG-RAN.
  • the first RAT is 5G NR.
  • the first cellular system is a 5GS.
  • the second cellular system is an EPS.
  • the second RAT is LTE.
  • a radio access node for a cellular radio access network for performing handover of an IMS session used for IMS voice for a wireless device from a non-cellular access network to a cellular access network is adapted to ... receive, from the wireless device, a message that initiates handover of an IMS session used for IMS voice for the wireless device from a non-cellular access network to a cellular access network and send, to the wireless device, information that informs the wireless device that fallback from a first cellular system to a second cellular system or from a first RAT to a second RAT is ongoing for the IMS session.
  • a radio access node for a cellular radio access network for performing handover of an IMS session used for IMS voice for a wireless device from a non-cellular access network to a cellular access network comprises processing circuitry configured to cause the radio access node to receive, from the wireless device, a message that initiates handover of an IMS session used for IMS voice for the wireless device from a non-cellular access network to a cellular access network and send, to the wireless device, information that informs the wireless device that fallback from a first cellular system to a second cellular system or from a first RAT to a second RAT is ongoing for the IMS session.
  • Figure 1 illustrates one example of a wireless communication system in which a User Equipment (UE) has the capability to utilize both a cellular access network, which is shown as a Third Generation Partnership Project (3GPP) (Radio) Access Network ((R)AN) and a Wireless Local Area Network (WLAN), which is shown as a Non-3GPP (N3GPP) AN;
  • 3GPP Third Generation Partnership Project
  • R Radio
  • WLAN Wireless Local Area Network
  • Figure 2 illustrates an example of the wireless communication system of Figure 1 in which the 3GPP core network is a Fifth Generation Core (5GC);
  • 5GC Fifth Generation Core
  • FIG 3 illustrates an example of the wireless communication system of Figure 1 in which the 3GPP core network is an Evolved Packet Core (EPC);
  • EPC Evolved Packet Core
  • FIG. 4 illustrates a procedure for handover of an Internet Protocol (IP) Multimedia Subsystem (IMS) session used for IMS voice from a non-cellular access network to a cellular system in accordance with one example embodiment of the present disclosure
  • IP Internet Protocol
  • IMS Internet Multimedia Subsystem
  • FIGS. 5 and 6 are flow charts that illustrates the operation of a wireless device (e.g., a User Equipment (UE)) in accordance with some embodiments of the present disclosure
  • UE User Equipment
  • Figure 7 is a schematic block diagram of a network node according to some embodiments of the present disclosure.
  • Figure 8 is a schematic block diagram that illustrates a virtualized embodiment of the network node of Figure 7 according to some embodiments of the present disclosure
  • Figure 9 is a schematic block diagram of the network node of Figure 7 according to some other embodiments of the present disclosure.
  • FIG. 10 is a schematic block diagram of a User Equipment device (UE) according to some embodiments of the present disclosure
  • Figure 11 is a schematic block diagram of the UE of Figure 10 according to some other embodiments of the present disclosure.
  • Figure 12 is a reproduction of Figure 4.13.6.X-1 from Third 3GPP Change Request (CR) S2-1912644.
  • Radio Node As used herein, a "radio node” is either a radio access node or a wireless communication device.
  • Radio Access Node As used herein, a “radio access node” or “radio network node” or “radio access network node” is any node in a Radio Access Network (RAN) of a cellular communications network that operates to wirelessly transmit and/or receive signals.
  • RAN Radio Access Network
  • a radio access node examples include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), a relay node, a network node that implements part of the functionality of a base station or a network node that implements a gNB Distributed Unit (gNB-DU)) or a network node that implements part of the functionality of some other type of radio access node.
  • a base station e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B
  • Core Network Node is any type of node in a core network or any node that implements a core network function.
  • Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Flome Subscriber Server (HSS), or the like.
  • MME Mobility Management Entity
  • P-GW Packet Data Network Gateway
  • SCEF Service Capability Exposure Function
  • HSS Flome Subscriber Server
  • a core network node examples include a node implementing a Access and Mobility Function (AMF), a UPF, a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.
  • AMF Access and Mobility Function
  • UPF User Planet Control Function
  • UPF Unified Data Management
  • a "communication device” is any type of device that has access to an access network.
  • Some examples of a communication device include, but are not limited to: mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or Personal Computer (PC).
  • the communication device may be a portable, hand-held, computer-comprised, or vehicle- mounted mobile device, enabled to communicate voice and/or data via a wireless or wireline connection.
  • Wireless Communication Device One type of communication device is a wireless communication device, which may be any type of wireless device that has access to (i.e., is served by) a wireless network (e.g., a cellular network).
  • a wireless communication device include, but are not limited to: a User Equipment device (UE) in a 3GPP network, a Machine Type Communication (MTC) device, and an Internet of Things (IoT) device.
  • UE User Equipment
  • MTC Machine Type Communication
  • IoT Internet of Things
  • Such wireless communication devices may be, or may be integrated into, a mobile phone, smart phone, sensor device, meter, vehicle, household appliance, medical appliance, media player, camera, or any type of consumer electronic, for instance, but not limited to, a television, radio, lighting arrangement, tablet computer, laptop, or PC.
  • the wireless communication device may be a portable, hand-held, computer-comprised, or vehicle-mounted mobile device, enabled to communicate voice and/or data via a wireless connection.
  • Network Node As used herein, a "network node” is any node that is either part of the radio access network or the core network of a cellular communications network/ system.
  • RRC Radio Resource Control
  • NR New Radio
  • SIP Session Initiation Protocol
  • the UE is not told why the audio 5QI-1 is not established.
  • the IMS layer (application layer) in the UE is not aware of what is happening and may assume that the IMS session has to be terminated and hence prematurely tear down the IMS session during the EPS FB procedure.
  • the UE when the UE transfers the Voice over Wireless Local Area Network (VoWLAN) session to 5GS, and Evolved Packet System (EPS) Fallback (FB) is initiated, the Next Generation Radio Access Network (NG- RAN) indicates EPS FB in the Radio Resource Control (RRC) layer to the UE.
  • the UE may also remember that EPS FB is supported for the current Public Land Mobile Network (PLMN) and registration area for future use (i.e., the UE may store information that indicates that EPS FB is supported for the current PLMN and registration area).
  • PLMN Public Land Mobile Network
  • registration area for future use
  • Embodiments of the present disclosure may provide one or more of the following advantages:
  • embodiments of the proposed solution can ensure the voice call is not terminated at WLAN handover to 5GS subjected to EPS FB, as well as reduce the duration of voice interruption.
  • embodiments of the solution provide a Radio Access Technology (RAT) / EPS Fallback indication from the NG-RAN to the UE, which avoids looping this information via the AMF to the UE.
  • RAT Radio Access Technology
  • FIG. 1 illustrates one example of a wireless communication system 100 in which embodiments of the present disclosure may be implemented.
  • a UE 102 has the capability to utilize both a cellular access network, which is shown as a 3GPP (Radio) Access Network ((R)AN) 104, and a Wireless Local Area Network (WLAN) access network, which is shown as a Non-3GPP (N3GPP) AN 106.
  • 3GPP Radio
  • WLAN Wireless Local Area Network
  • the 3GPP (R)AN 104 is, in this example, a Next Generation RAN (NG- RAN) including both Next Generation eNBs (ng-eNBs) providing LTE/E-UTRAN services towards the UE 102 and 5G NR base stations (gNBs) providing NR user plane and control plane services towards the UE 112.
  • NG-RAN Next Generation RAN
  • ng-eNBs Next Generation eNBs
  • gNBs 5G NR base stations
  • the 3GPP (R)AN 104 is connected to a 3GPP core network 108.
  • the 3GPP core network(s) 108 include a 5G Core (5GC) (see, e.g., Figure 2 where the 5GC 200 is shown) and an Evolved Packet Core (EPC) (see, e.g., Figure 3 where the EPC 300 is shown).
  • 5GC 5G Core
  • EPC Evolved Packet Core
  • NG-RAN 5G system
  • 5GS 5G system
  • eNBs in an E-UTRAN and the EPC 300 form an Evolved Packet System (EPS).
  • EPS Evolved Packet System
  • the N3GPP AN 106 is connected to the 3GPP core network 108 via a gateway or interworking function, which is shown as an evolved Packet Data Gateway (ePDG) / N3GPP Inter-Working Function (N3IWF) 110.
  • ePDG evolved Packet Data Gateway
  • N3IWF N3GPP Inter-Working Function
  • the term “ePDG” is used for 4G, and the term “N3IWF” is used for 5G.
  • the ePDG can also be connected to SMF+PGW-C in 5GC.
  • the 3GPP core network(s) 108 is(are) connected to an Internet Protocol (IP) Multimedia Subsystem (IMS) 112, as will be appreciated by one of skill in the art.
  • IP Internet Protocol
  • IMS Internet Multimedia Subsystem
  • a WLAN access network i.e., the incoming access network
  • 3GPP access network the present disclosure is not limited thereto.
  • the incoming access network is not limited to being a WLAN access network.
  • Other types of incoming access networks may be used.
  • Embodiments of the present disclosure apply to any handover where it is performed through a registration or attach procedure. For NR and LTE, if there is no N26 interface and the NG RAN and LTE access network also do not support Xn or X2, embodiments of the present disclosure could apply as well if the UE has to "handover" when moving from NG-RAN to LTE or vice versa.
  • Figures 2 and 3 illustrate two specific examples of cellular communication systems.
  • Figure 2 illustrates a 5GS, which may be formed by the 3GPP RAN 104 and 3GPP core network 108 of Figure 1 where the 3GPP RAN 104 in the 5GS is a NG-RAN and the 3GPP core network 108 in the 5GS is the 5GC 200.
  • Figure 3 illustrates an EPS which is formed by the EPC 300 and E-UTRAN 301.
  • the E-UTRAN may include eNBs that are separate from the NG-RAN 104 and/or include ng-eNBs included in the NG-RAN 104.
  • the 5GC 200 includes a number of Network Functions (NFs) connected by service-based interfaces in the control plane.
  • An NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.
  • the 5GC 200 includes a UPF 202, an SMF 204, an AMF 206, an AUSF 208, a NSSF 210, a NEF 212, a NRF 214, a PCF 216, a UDM 218, and an Application Function (AF) 220.
  • AF Application Function
  • Figure 2 illustrates the 5GC 200 as a service-based architecture
  • a reference point representation may alternatively be used.
  • Reference point representations of the 5G network architecture are used to develop detailed call flows in the normative standardization.
  • the 5GC 200 aims at separating a user plane and a control plane.
  • the user plane carries user traffic while the control plane carries signaling in the network.
  • the UPF 202 is in the user plane and all other NFs, i.e., the SMF 204, AMF 206, AUSF 208, NSSF 210, NEF 212, NRF 214, PCF 216, UDM 218, and AF 220, are in the control plane. Separating the user and control planes guarantees each plane resource to be scaled independently. It also allows UPFs 202 to be deployed separately from control plane functions in a distributed fashion. In this architecture, the UPFs 202 may be deployed very close to UEs 102 to shorten the Round Trip Time (RTT) between the UEs 102 and the data network for some applications requiring low latency.
  • RTT Round Trip Time
  • the core 5G network architecture is composed of modularized functions.
  • the AMF 206 and SMF 204 are independent functions in the control plane. Separating the AMF 206 and SMF 204 allows for independent evolution and scaling.
  • Other control plane functions like the PCF 216 and AUSF 208 can be separated as shown in Figure 2.
  • Modularized function design enables the 5G core network to support various services flexibly.
  • Each NF interacts with another NF directly. It is possible to use intermediate functions to route messages from one NF to another NF.
  • a set of interactions between two NFs is defined as a service so that its reuse is possible. This service enables support for modularity.
  • the user plane supports interactions such as forwarding operations between different UPFs 202.
  • the service(s) that an NF provides to other authorized NFs can be exposed to the authorized NFs through the service-based interface.
  • the service-based interfaces are sometimes indicated by the letter "N" followed by the name of the NF (e.g., Namf for the service based interface of the AMF 206 and Nsmf for the service based interface of the SMF 204, etc.).
  • N service based interfaces
  • Nl service based interfaces
  • the AMF 206 provides UE-based authentication, authorization, mobility management, etc.
  • a UE 102 even using multiple access technologies is basically connected to a single AMF 206 because the AMF 206 is independent of the access technologies.
  • the SMF 204 is responsible for session management and allocates IP addresses to UEs 102. It also selects and controls the UPF 202 for data transfer. If a UE 102 has multiple sessions, different SMFs 204 may be allocated to each session to manage them individually and possibly provide different functionalities per session.
  • the AF 220 provides information on the packet flow to the PCF 216 responsible for policy control in order to support Quality of Service (QoS).
  • QoS Quality of Service
  • the PCF 216 determines policies about mobility and session management to make the AMF 206 and SMF 204 operate properly.
  • the AUSF 208 supports an authentication function for the UEs 102 or similar and thus stores data for authentication of the UEs 102 or similar while the UDM 218 stores subscription data of the UE 102.
  • the 5GC 200 includes a N3IWF 222 that provides an interface between the N3GPP AN 106 and the 5GC 200. While not necessary for understanding the present disclosure, for additional details regarding the N3IWF 222, the interested reader is directed to 3GPP TS 23.501 and 23.502.
  • the IMS 112 includes various IMS entities such as, for example, a Proxy Call Session Control Function (P-CSCF) 224, an Interrogating Call Session Control Function (I-CSCF) 226, a Serving Call Session Control Function (S-CSCF) 228, an Access Transfer Control Function (ATCF) 230, and an Access Gateway (AGW) 232.
  • P-CSCF Proxy Call Session Control Function
  • I-CSCF Interrogating Call Session Control Function
  • S-CSCF Serving Call Session Control Function
  • ATCF Access Transfer Control Function
  • AGW Access Gateway
  • the EPC 300 includes a number of core network entities such as, e.g., a Serving Gateway (S-GW) 302, a P-GW 304, an MME 306, a FISS 308, and a Policy and Charging Rules Function (PCRF) 310.
  • S-GW Serving Gateway
  • P-GW Packet Control Function
  • MME Mobility Management Entity
  • FISS 308 Policy and Charging Rules Function
  • PCRF Policy and Charging Rules Function
  • the EPC 300 includes an ePDG 312 that provides an interface between the EPC 300 and the N3GPP AN 106. While not necessary for understanding the present disclosure, for additional details regarding the ePDG 312, the interested reader is directed to 3GPP TS 23.402. [0065] Now, some specific embodiments of the present disclosure will be described.
  • the 3GPP RAN 104 is a 3GPP NG-RAN; however, the embodiments disclosed herein are not limited thereto.
  • the NG-RAN indicates (e.g., in the RRC layer) to the UE that EPS FB is ongoing e.g., so that the IMS layer / stack in the UE is informed that EPS Fallback is taking place so the bearer for voice media will be established soon and there is no need to take any further action.
  • the UE may also remember that EPS FB is supported for the current PLMN and registration area for future use. The next time that the UE is in this registration area, the UE may decide to transfer a VoWLAN session directly to EPS (i.e., without going to 5GS first) to expedite the session transfer and avoid delays.
  • EPS Protocol Data Unit
  • Figure 4 illustrates a procedure for transfer of a Protocol Data Unit (PDU) session used for IMS voice from non-3GPP access to 5GS in accordance with at least some aspects of the embodiments described herein.
  • PDU Protocol Data Unit
  • the UE 102 When the UE 102 has an ongoing IMS voice session via non-3GPP access 106 using ePDG or N3IWF 110 and the session is transferred to the NG-RAN 104, depending on the selected RAT in 5GS (NR or E-UTRA) and the support of EPS/inter-RAT fallback in the NG-RAN 104, either the IMS voice session continues over NG-RAN (E-UTRA) or EPS/inter-RAT fallback is triggered.
  • 5GS NR or E-UTRA
  • Steps 400, 402, and 404 apply to either of the above two cases.
  • Step 400 The UE 102 has an ongoing IMS voice session via the non-3GPP access 106 using the ePDG or N3IWF 110.
  • the UE 112 is triggered to move to 3GPP access and camps in the NG-RAN 104.
  • Step 402 If the UE 102 is not registered via 3GPP access, the UE 112 initiates the Registration procedure as defined in clause 4.2.2.2.2 of 3GPP 23.502 (e.g., V16.2.0).
  • Step 404 If the UE 112 is not aware that that voice over NR is not supported in the current Registration area, the UE 112 initiates PDU session establishment for the PDU session used for IMS voice service in order to initiate handover from EPC/ePDG to 5GS as defined in clause 4.11.4.1 step 2 of 3GPP TS 23.502 (e.g., V16.2.0) or to initiate handover from N3IWF to 3GPP access in 5GC in step 2 of clauses 4.9.2.1 and 4.9.2.3 of 3GPP 23.502 (e.g., V16.2.0).
  • the SMF 204 accepts the successful PDU session transfer to the UE 112 in NAS.
  • the NG-RAN e.g., a gNB in the NG-RAN 104) informs the UE 112 (e.g., in RRC) that EPS/RAT FB is ongoing.
  • the UE 112 If the UE 112 is aware that voice over NR may not be natively supported in the current Registration area, the UE 112 performs handover to EPS as described in 3GPP TS 23.402 (e.g., V16.0.0). The remaining steps are not executed. o NOTE: If the UE 112 is not aware that EPS-FB is ongoing, the IMS session will possibly be torn down given that the 5QI-1 QoS flow is not established over NR.
  • the UE 112 may be aware that voice over NR may not be natively supported in the current Registration area based on stored information (e.g., from a prior performance of the procedure of Figure 4 within the same Registration area during which the UE 112 was informed that 5GI-1 has not been accepted because of an EPS-FB (or RAT FB)). Note, however, that other mechanisms may be used by which the UE 112 becomes aware that voice over NR may not be natively supported in the current Registration area.
  • the NG-RAN may decide to trigger EPS or inter-RAT fallback, taking into account UE capabilities of the UE 112, indication from AMF 206 that "Redirection for EPS fallback for voice is possible" (received as part of initial context setup as defined in 3GPP TS 38.413 (e.g., V15.5.0)), network configuration (e.g. N26 availability configuration), and radio conditions.
  • the NG-RAN e.g., the gNB in the NG-RAN
  • Step 408 The NG-RAN (e.g., the gNB in the NG-RAN) responds indicating rejection to set up the Quality of Service (QoS) flow for IMS voice received in step 404 towards the PGW-C (control plane portion of the PGW 304) + SMF 204 (or FI-SMF+ PGW-C via V-SMF, in case of roaming scenario) via AMF 206 with an indication that mobility due to fallback for IMS voice is ongoing.
  • the PGW- C+SMF executes the release of resources in non-3GPP AN 106 as specified in clause 4.11.4.1 and clauses 4.9.2.1 and 4.9.2.3 (of 3GPP TS 23.502 (e.g., V16.2.0).
  • the timing of executing the release of resources in non-3GPP AN 106 will depend on whether the NG-RAN 104 decides to trigger EPS or inter-RAT fallback but will take place at least after step 408.
  • Step 410 If EPS fallback is triggered, steps 5-7 from clause 4.13.6.1(of 3GPP TS 23.502 (e.g., V16.2.0) are executed. If inter-RAT Fallback for IMS voice is triggered, steps 5-6 from clause 4.13.6.2 (of 3GPP TS 23.502 (e.g., V16.2.0) are executed.
  • FIG. 5 is a flow chart that illustrates the operation of the UE 112 in accordance with at least some aspects of the embodiments described above. Optional steps are represented by dashed lines/boxes.
  • the UE 112 detects a trigger for handover of an IMS session used for IMS voice from a non-cellular access network (e.g., the N3GPP RAN 106 such as, e.g., a WLAN) to a cellular access network (e.g., the 3GPP RAN 104 such as, e.g., a NG-RAN), as described above (step 500).
  • the UE 112 initiates a registration procedure for registration with the cellular access network (step 502).
  • the UE 112 Upon detecting the trigger and optionally registering with the cellular access network, the UE 112 initiates handover of the IMS session used for IMS voice from the non-cellular access network to the cellular access network, as described above (step 504).
  • This handover initiation may be made with respect to a first cellular system (e.g., a 5GS).
  • a first cellular system e.g., a 5GS
  • fallback for the IMS session is ongoing from the first cellular system (e.g., 5GS) associated with the cellular access network to a second cellular system (e.g., EPS) associated with the cellular access network.
  • the UE 112 receives, from the cellular access network, information that indicates that such a fallback is ongoing, as described above (step 506).
  • the UE 112 Based on the received information, the UE 112 stores information that indicates that fallback from the first cellular system (e.g., 5GS) to the second cellular system (e.g., EPS) is supported (e.g., that EPS fallback is supported) in a current registration area of the UE 112 within the cellular access network (step 508).
  • the UE 112 communicates with the cellular access network for the aforementioned fallback of the IMS session, as described above (step 510).
  • Figure 6 is a flow chart that illustrates the operation of the UE 112 in accordance with at least some aspects of the embodiments described above. Optional steps are represented by dashed lines/boxes.
  • the processes of Figures 5 and 6 may be performed by the UE 112 for two separate IMS sessions while in the same registration area of the cellular access network.
  • the UE 112 detects a trigger for handover of an IMS session used for IMS voice from a non-cellular access network (e.g., the N3GPP RAN 106 such as, e.g., a WLAN) to a cellular access network (e.g., the 3GPP RAN 104 such as, e.g., a NG-RAN), as described above (step 600).
  • the UE 112 initiates a registration procedure for registration with the cellular access network (step 602).
  • the UE 112 Upon detecting the trigger and optionally registering with the cellular access network, the UE 112 determines that it is aware that fallback from a first cellular system (e.g., 5GS) to a second cellular system (e.g., EPS) is supported in a current registration area of the UE 112 within the cellular access network (step 604). For example, the UE 112 may determine that it has stored information (from a prior performance of the process of Figure 5 for the same registration area) that indicates that fallback from a first cellular system (e.g., 5GS) to a second cellular system (e.g., EPS) is supported in the current registration area of the UE 112 within the cellular access network (step 604).
  • a first cellular system e.g., 5GS
  • EPS second cellular system
  • the UE 112 Upon making the determination of step 604, the UE 112 initiates handover of the IMS session from the non-cellular access network to the second cellular system (e.g., EPS), as described above (step 606). This is instead of initiating handover of the IMS session to the first cellular system (e.g., 5GS) associated with the cellular access network, as was done in step 504 of Figure 5. In this manner, the UE 112 is able to initiate handover directly to the second cellular system, rather than first initiating handover to the first cellular system and then falling back to the second cellular system.
  • the second cellular system e.g., EPS
  • FIG. 7 is a schematic block diagram of a network node 700 according to some embodiments of the present disclosure.
  • the network node 700 may be, for example, a radio access node (e.g., a base station such as a gNB or ng-eNB in the NG-RAN or an eNB in a E-UTRAN), a core network node (e.g., a node that implements all or part of the functionality of a core network entity or core network function such as, e.g., a N3IWF, ePDG, AMF, MME,
  • a radio access node e.g., a base station such as a gNB or ng-eNB in the NG-RAN or an eNB in a E-UTRAN
  • a core network node e.g., a node that implements all or part of the functionality of a core network entity or core network function such as, e.g., a N3IWF,
  • the network node 700 includes a control system 702 that includes one or more processors 704 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory 706, and a network interface 708.
  • processors 704 e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like
  • the one or more processors 704 are also referred to herein as processing circuitry.
  • the network node 700 may also include one or more radio units 710 that each includes one or more transmitters 712 and one or more receivers 714 coupled to one or more antennas 716.
  • the radio units 710 may be referred to or be part of radio interface circuitry.
  • the radio unit(s) 710 is external to the control system 702 and connected to the control system 702 via, e.g., a wired connection (e.g., an optical cable).
  • a wired connection e.g., an optical cable
  • the radio unit(s) 710 and potentially the antenna(s) 716 are integrated together with the control system 702.
  • the one or more processors 704 operate to provide one or more functions of the network node 700 as described herein (e.g., one or more functions of a radio access node, core network node, or IMS node as described herein, e.g., with respect to Figure 4).
  • the function(s) are implemented in software that is stored, e.g., in the memory 706 and executed by the one or more processors 704.
  • Figure 8 is a schematic block diagram that illustrates a virtualized embodiment of the network node 700 according to some embodiments of the present disclosure. Again, optional features are represented by dashed boxes.
  • a "virtualized" network node is an implementation of the network node 700 in which at least a portion of the functionality of the network node 700 is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)).
  • the network node 700 includes one or more processing nodes 800 coupled to or included as part of a network(s) 802.
  • Each processing node 800 includes one or more processors 804 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 806, and a network interface 808.
  • the network node 700 may also include the control system 702 and/or the one or more radio units 710, as described above. If present, the control system 702 or the radio unit(s) is connected to the processing node(s) 800 via the network 802.
  • functions 810 of the network node 700 described herein are implemented at the one or more processing nodes 800 or distributed across the one or more processing nodes 800 and the control system 702 and/or the radio unit(s) 710 in any desired manner.
  • some or all of the functions 810 of the network node 700 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) 800.
  • a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the network node 700 or a node (e.g., a processing node 800) implementing one or more of the functions 810 of the network node 700 in a virtual environment according to any of the embodiments described herein (e.g., one or more functions of a radio access node, core network node, or IMS node as described herein, e.g., with respect to Figure 4) is provided.
  • a carrier comprising the aforementioned computer program product is provided.
  • the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).
  • FIG 9 is a schematic block diagram of the network node 700 according to some other embodiments of the present disclosure.
  • the network node 700 includes one or more modules 900, each of which is implemented in software.
  • the module(s) 900 provide the functionality of the network node 700 described herein (e.g., one or more functions of a radio access node, core network node, or IMS node as described herein, e.g., with respect to Figure 4).
  • This discussion is equally applicable to the processing node 800 of Figure 8 where the modules 900 may be implemented at one of the processing nodes 800 or distributed across multiple processing nodes 800 and/or distributed across the processing node(s) 800 and the control system 702.
  • FIG 10 is a schematic block diagram of a wireless communication device 1000 (e.g., UE such as UE 102) according to some embodiments of the present disclosure.
  • the wireless communication device 1000 includes one or more processors 1002 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory 1004, and one or more transceivers 1006 each including one or more transmitters 1008 and one or more receivers 1010 coupled to one or more antennas 1012.
  • the transceiver(s) 1006 includes radio-front end circuitry connected to the antenna(s) 1012 that is configured to condition signals communicated between the antenna(s) 1012 and the processor(s) 1002, as will be appreciated by on of ordinary skill in the art.
  • the processors 1002 are also referred to herein as processing circuitry.
  • the transceivers 1006 are also referred to herein as radio circuitry.
  • the functionality of the wireless communication device 1000 described above may be fully or partially implemented in software that is, e.g., stored in the memory 1004 and executed by the processor(s) 1002.
  • the wireless communication device 1000 may include additional components not illustrated in Figure 10 such as, e.g., one or more user interface components (e.g., an input/output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and/or the like and/or any other components for allowing input of information into the wireless communication device 1000 and/or allowing output of information from the wireless communication device 1000), a power supply (e.g., a battery and associated power circuitry), etc.
  • user interface components e.g., an input/output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and/or the like and/or any other components for allowing input of information into the wireless communication device 1000 and/or allowing output of information from the wireless communication device 1000
  • a power supply e.g., a battery and associated power circuitry
  • a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of the wireless communication device 1000 according to any of the embodiments described herein is provided.
  • a carrier comprising the aforementioned computer program product is provided.
  • the carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).
  • FIG 11 is a schematic block diagram of the wireless communication device 1000 according to some other embodiments of the present disclosure.
  • the wireless communication device 1000 includes one or more modules 1100, each of which is implemented in software.
  • the module(s) 1100 provide the functionality of the wireless communication device 1000 described herein.
  • any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses.
  • Each virtual apparatus may comprise a number of these functional units.
  • These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include DSPs, special-purpose digital logic, and the like.
  • the processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as ROM, RAM, cache memory, flash memory devices, optical storage devices, etc.
  • Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein.
  • the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure.
  • Embodiment 1 A method of operation of a wireless device (112) to perform handover of an Internet Protocol Multimedia Subsystem, IMS, session used for IMS voice from a non-cellular access network (106) to a cellular access network (104), comprising:
  • Embodiment 2 The method of claim 1 wherein the cellular access network (104) is a Next Generation Radio Access Network, NG-RAN.
  • the cellular access network (104) is a Next Generation Radio Access Network, NG-RAN.
  • Embodiment 3 The method of claim 2 wherein the first cellular system is a Fifth Generation System, 5GS.
  • Embodiment 4 The method of claim 3 wherein the second cellular system is an Evolved Packet System, EPS.
  • EPS Evolved Packet System
  • Embodiment 5 The method of any of claims 1 to 4 further comprising communicating (410; 510) with the cellular access network (104) for fallback from the first cellular system (e.g., 5GS) to the second cellular system (e.g., EPS).
  • first cellular system e.g., 5GS
  • second cellular system e.g., EPS
  • Embodiment 6 The method of any of claims 1 to 5 further comprising, at a subsequent time, in order to perform handover of a second IMS session used for IMS voice from a non-cellular access network (106) to the cellular access network (104) while the wireless device (112) is in the same registration area within the cellular access network (104):
  • 5GS to the second cellular system (e.g., EPS) is supported in the registration area in which the wireless device (112) is currently located (at the subsequent time) within the cellular access network (104); and o upon determining (404; 604) that the wireless device (112) is aware that fallback from the first cellular system (e.g., 5GS) to the second cellular system (e.g., EPS) is supported in the registration area, initiating (606) a handover of the IMS session used for IMS voice from the non-cellular access network (106) to the second cellular system (e.g., EPS).
  • the first cellular system e.g., 5GS
  • the second cellular system e.g., EPS
  • Embodiment 7 The method of claim 6 wherein the second cellular system (e.g., EPS) comprises one or more base stations (e.g., ng-eNBs) in the cellular access network (104) that support a second RAT (e.g., LTE) and a core network (e.g., EPC) of the second cellular system (e.g., EPS).
  • a second RAT e.g., LTE
  • EPC core network of the second cellular system
  • Embodiment 8 A method of operation of a wireless device (112) to perform handover of an Internet Protocol Multimedia Subsystem, IMS, session used for IMS voice from a non-cellular access network (106) to a cellular access network (104), comprising: • detecting (400; 600) a trigger for handover of an IMS session used for IMS voice from a non-cellular access network (106) to a cellular access network (104);
  • the trigger o determining (404; 604) that the wireless device (112) is aware that fallback from a first cellular system (e.g., 5GS) to a second cellular system (e.g., EPS) is supported in a current registration area of the wireless device (112) within the cellular access network (104); and o upon determining (404; 604) that the wireless device (112) is aware that fallback from the first cellular system (e.g., 5GS) to the second cellular system (e.g., EPS) is supported in the current registration area of the wireless device (112) within the cellular access network (104), initiating (606) a handover of the IMS session used for IMS voice from the non- cellular access network (106) to the second cellular system (e.g., EPS).
  • a first cellular system e.g., 5GS
  • EPS e.g., EPS
  • Embodiment 9 The method of claim 8 wherein the second cellular system comprises one or more base stations (e.g., ng-eNBs) in the cellular access network (104) that support a second RAT (e.g., LTE) and a core network (e.g., EPC) of the second cellular system (e.g., EPS).
  • a second RAT e.g., LTE
  • a core network e.g., EPC
  • Embodiment 10 The method of claim 8 or 9 wherein the cellular access network (104) is a Next Generation Radio Access Network, NG-RAN.
  • the cellular access network (104) is a Next Generation Radio Access Network, NG-RAN.
  • Embodiment 11 The method of claim 10 wherein the first cellular system is a Fifth Generation System, 5GS.
  • Embodiment 12 The method of claim 10 wherein the second cellular system is an Evolved Packet System, EPS.
  • EPS Evolved Packet System
  • Embodiment 13 A wireless device (112) for performing handover of an Internet Protocol Multimedia Subsystem, IMS, session used for IMS voice from a non- cellular access network (106) to a cellular access network (104), the wireless device (112) adapted to perform the method of any of claims 1 to 12.
  • IMS Internet Protocol Multimedia Subsystem
  • Embodiment 14 The wireless device (112) of claim 13 wherein the wireless device (112) comprises: one or more transmitters (QQ508); one or more receivers (QQ510); and processing circuitry (QQ502) associated with the one or more transmitters (QQ508) and the one or more receivers (QQ510), the processing circuitry (QQ502) configured to cause the wireless device (112) to perform the method of any of claims 1 to 12.
  • the wireless device (112) comprises: one or more transmitters (QQ508); one or more receivers (QQ510); and processing circuitry (QQ502) associated with the one or more transmitters (QQ508) and the one or more receivers (QQ510), the processing circuitry (QQ502) configured to cause the wireless device (112) to perform the method of any of claims 1 to 12.
  • Embodiment 15 A method of operation of a radio access node (e.g., gNB or ng-eNB) in a cellular radio access network (104) to perform handover of an Internet Protocol Multimedia Subsystem, IMS, session used for IMS voice for a wireless device (112) from a non-cellular access network (106) to a cellular access network (104), comprising:
  • a radio access node e.g., gNB or ng-eNB
  • IMS Internet Protocol Multimedia Subsystem
  • Embodiment 16 The method of claim 15 further comprising communicating with the wireless device (112) and one or more other network nodes to provide fallback for the IMS session from the first cellular system (e.g., 5GS) to the second cellular system (e.g., EPS) or from the first radio access technology, RAT, (e.g., 5G NR) to the second RAT (e.g., LTE).
  • first cellular system e.g., 5GS
  • RAT e.g., 5G NR
  • LTE second RAT
  • Embodiment 17 The method of claim 15 or 16 wherein the cellular access network (104) is a Next Generation Radio Access Network, NG-RAN.
  • the cellular access network (104) is a Next Generation Radio Access Network, NG-RAN.
  • Embodiment 18 The method of claim 17 wherein the first RAT is 5G NR.
  • Embodiment 19 The method of claim 17 or 18 wherein the first cellular system is a Fifth Generation System, 5GS.
  • Embodiment 20 The method of claim 19 wherein the second cellular system is an Evolved Packet System, EPS.
  • EPS Evolved Packet System
  • Embodiment 21 The method of any of claims 18 to 20 wherein the second RAT is LTE.
  • Embodiment 22 A radio access node (e.g., gNB or ng-eNB) in a cellular radio access network (104) to perform handover of an Internet Protocol Multimedia Subsystem, IMS, session used for IMS voice for a wireless device (112) from a non- cellular access network (106) to a cellular access network (104), the radio access node adapted to perform the method of any of claims 15 to 21.
  • IMS Internet Protocol Multimedia Subsystem
  • Embodiment 23 The radio access node (QQ200) of claim 22 wherein the radio access node (QQ200) comprises: processing circuitry (QQ204, QQ304) configured to cause the radio access node (QQ200) to perform the method of any of claims 15 to

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Abstract

L'invention concerne des systèmes et des procédés de transfert d'une session de sous-système multimédia (IMS) à protocole Internet (IP) depuis un réseau d'accès non cellulaire vers un réseau d'accès cellulaire. Dans certains modes de réalisation, un procédé de fonctionnement d'un dispositif sans fil comprend la détection d'un déclencheur pour le transfert d'une session IMS utilisée pour une session vocale IMS d'un réseau d'accès non cellulaire à un réseau d'accès cellulaire et l'initiation d'un transfert de la session IMS depuis le réseau d'accès non cellulaire vers un réseau d'accès cellulaire pour un premier système cellulaire. Le procédé comprend en outre la réception, en provenance du réseau d'accès cellulaire, d'informations qui indiquent au dispositif sans fil que le repli du premier système cellulaire vers un second système cellulaire est en cours pour la session IMS et la mémorisation des informations qui indiquent que le repli du premier système cellulaire vers le second système cellulaire est pris en charge dans une zone d'enregistrement dans laquelle le dispositif sans fil est actuellement situé.
PCT/IB2020/061543 2019-12-05 2020-12-04 Rétroaction d'ue epsfb au niveau d'un vowlan en vue d'un transfert de session 3gpp WO2021111414A1 (fr)

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Publication number Priority date Publication date Assignee Title
US12004019B2 (en) 2021-10-05 2024-06-04 Qualcomm Incorporated Techniques for improvement of voice over Wi-Fi to voice over cellular handovers

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