WO2019097498A1

WO2019097498A1 - Methods and apparatus for handover or redirection

Info

Publication number: WO2019097498A1
Application number: PCT/IB2018/059137
Authority: WO
Inventors: Ralf Keller; Peter Hedman; Paul Schliwa-Bertling
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2017-11-20
Filing date: 2018-11-20
Publication date: 2019-05-23

Abstract

Methods and apparatus are provided to handover or redirect a wireless device between a source network and a target network. In response to determining that a communication by the wireless device (100) is to be commenced, moving a first connection from a NG-RAN (350) to a E-UTRAN (250), and commencing the communication over the E-UTRAN (250) using the first connection. In response to determining that the communication has been terminated, moving the first connection or a second connection to the NG-RAN (350) from the E-UTRAN (250).

Description

METHODS AND APPARATUS FOR HANDOVER OR REDIRECTION

TECHNICAL FIELD

The present disclosure relates generally to interworking between Long Term Evolution (LTE) and New Radio (NR) networks and, more particularly, to handover and/or redirections procedures in mixed LTE/NR networks

BACKGROUND

The Third Generation Partnership Project (3GPP) standards for Fifth Generation (5G) networks, also know a New Radio (NR) networks, are currently under development. During the initial roll-out of NR networks, service providers are likely to phase in NR systems gradually and leverage existing LTE networks to provide service in areas where NR networks do not provide coverage. Therefore, interworking protocols are needed to enable interworking between NR and LTE networks to provide services (e.g., voice communication) not supported by the NR network in the area where the UE is located.

Several solutions are specified in 3GPP to enable interworking between NR and LTE networks. One approach to interworking is known as Evolved Packet System (EPS) fallback. EPS fallback is a procedure for triggering handover or redirect towards an Evolved Universal Terrestrial Radio Access (E-UTRA) node connected to the EPS in scenarios where a communication is not supported by the 5G Core (5GC). Another approach to interworking is known as Radio Access Technology (RAT) fallback. RAT fallback is a procedure for triggering handover/redirect towards an E-UTRA node connected a 5G Core (5GC) in scenarios where the communication is not supported by NR.

While procedures have been defined to support fallback from a NR network to a 4G network to provide services not supported by the NR network in the area where the UE is located, no procedure currently exists for moving the UE back from the 4G network to the NR network or NG RAN when a communication that precipitated an EPS fallback or RAT fallback ends.

SUMMARY

Certain aspects of the present disclosure and their embodiments may provide solutions to these or other challenges. For example, the source RAT (e.g., NG-RAN) may provide a target RAT (e.g., E-UTRAN) an indication that a handover or redirection of a UE or wireless device from the source RAT to the target RAT is or was triggered because of Quality of Service (QoS) flow establishment or request for a communication unsupported by the NG-RAN, and not due to other conditions. The indication may be provided before, during or after handover or redirection. In some examples, this may help the target RAT to move the UE or wireless device back to NG- RAN once the QoS flow (e.g., in case of RAT fallback) or QCI=1 bearer (e.g., in case of EPS fallback) have been released (e.g., the communication has been terminated) or redirected back to the source RAT. In addition or alternatively, in some embodiments, the indication(s) (e.g., indicator(s)) can be used to differentiate failure cases and hence provide key performance indicators (KPIs).

There are, proposed herein, various embodiments which address one or more of the issues disclosed herein. For example, in one aspect, this disclosure provides a method performed by a wireless device for handover or redirection. The method comprises, in response to determining that a communication by the wireless device is to be commenced, moving a first connection to an Access Point Names (APN), such as the Internet Protocol (IP) Multimedia Subsystem (IMS), from a NG-RAN to a E-UTRAN, and commencing the communication over the E-UTRAN using the first connection.

In another aspect, this disclosure provides a method performed by a network node for handover or redirection of a wireless device. The method comprises determining that a wireless device connected to an E-UTRAN was previously connected to a NG-RAN and, in response to a determination that the wireless device has completed a communication through the E-UTRAN, causing the wireless device to handover or be redirected to the NG-RAN.

In some embodiments, for example, an indication that a wireless device is handed over or redirected from a NG-RAN to a E-UTRAN (e.g., due to fallback) is provided to the E-UTRAN (e.g., by the NG-RAN). The fallback or redirection may occur because, for example, the wireless device wishes to make a communication that is unsupported by the NG-RAN (e.g., voice call). Providing the indication may allow the E-UTRAN to quickly redirect or handover the wireless device back to the NG RAN upon termination of the communication. An indication may also be provided to the E-UTRAN of a PLMN ID of the NG-RAN node (e.g., gNB) to which the wireless device is connected before redirection or handover.

The handover/redirection procedures herein described enable the UE or wireless device to quickly move back to the source RAN after an EPS fallback or RAT fallback, or a redirection, to a target RAN has been performed. This may allow the wireless device to be quickly redirected or handed over back to, for example, the same PLMN in the NG-RAN upon termination of the communication. Additionally or alternatively, at least some embodiments may enable differentiation between failure cases and fallback.

One aspect of the disclosure comprises a method for handover or redirection implemented by a wireless device. The wireless device, in response to determining that a communication by the wireless device is to be commenced, moves a first connection from a NG- RAN to a E-UTRAN. After moving the first connection, the wireless device commences the communication over the E-UTRAN using the first connection, and, in response to determining that the communication has been terminated, moves the first connection or a second connection to the NG-RAN from the E-UTRAN. Another aspect of the disclosure comprises a wireless device configured to perform the method of the preceding paragraph.

Another aspect of the disclosure comprises computer program for a wireless device containing executable program instructions, that when executed by a processing circuit in a wireless device in a wireless communication network, causes the wireless device to perform the method described above.

Another aspect of the disclosure comprises a method for handover or redirection implemented by a network node. The network node determines that a wireless device connected to a E-UTRAN was previously connected to a NG-RAN. In response to a determination that the wireless device has completed a communication through the E-UTRAN), the network node causes the wireless device to handover or be redirected to the NG-RAN.

Another aspect of the disclosure comprises a network node configured to perform the method of the preceding paragraph.

Another aspect of the disclosure comprises computer program for a wireless device containing executable program instructions, that when executed by a processing circuit in a network node in a wireless communication network, causes the network node to perform the method described above.

The handover and redirection techniques as herein described enable the UE to quickly move back to source RAN after EPS fallback or RAT fallback has been performed. Further, the techniques enable differentiation between failure cases.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates an exemplary communication network 10 according to an embodiment.

Figure 2 is a reference architecture for an EPC.

Figure 3 is reference architecture for a 5GC.

Figures 4A and 4B are a call flow diagram for an EPS fallback procedure.

Figure 5 is a call flow diagram for a RAT fallback procedure.

Figure 6 is a call flow diagram for a handover from E-UTRAN to a NG-RAN.

Figure 7A is a flow chart of an exemplary method implemented by a UE.

Figure 7B illustrates an exemplary method implemented by UE for handover or redirection.

Figure 8 is a flow chart of an exemplary method implemented by a base station.

Figure 9 illustrates a UE according to an embodiment. Figure 10 illustrates a network node according to an embodiment.

Figure 1 1 is a functional block diagram of a UE according to an embodiment.

Figure 12 is a functional block diagram of a network node according to an embodiment.

Figure 13 illustrates a wireless network in accordance with some embodiments

Figure 14 illustrates a user Equipment in accordance with some embodiments

Figure 15 illustrates a virtualization environment in accordance with some embodiments

Figure 16 illustrates a telecommunication network connected via an intermediate network to a host computer in accordance with some embodiments

Figure 17 illustrates a host computer communicating via a base station with a user equipment over a partially wireless connection in accordance with some embodiments

Figures 18 - 21 illustrate methods implemented in a communication system including a host computer, a base station and a user equipment in accordance with some embodiments

DETAILED DESCRIPTION

Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art. Additional information may also be found in the document(s) provided in the Appendix.

The examples provided below are in the context of fallback and handover between networks. However, these are merely illustrative examples and the examples may also be applied to redirection of a wireless device between networks.

Figure 1 illustrates a mixed 4G/5G communication network 10 according to one embodiment. The communication network 10 comprises a LTE network 200, also known as an Evolved Packet System (EPS), and a NR network 300, also known as a 5G System (5GS). The LTE network 200 comprises an Evolved Packet Core (EPC) 210 and a LTE radio access network (RAN), also known as an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) 250. The E-UTRAN 250 comprises a plurality of LTE base stations, also known as Evolved NodeBs (eNBs) 260 serving respective cells within the coverage area of the LTE network 200. The eNBs 260 provide UEs 100 within the coverage connection to the EPC 210 and communicate with the UEs 200 according to the LTE standards. Similarly, the NR network 300 comprises a 5G Core (5GC) 310 and a Next Generation (NG) RAN (NG-RAN) 350. The NG-RAN comprises a plurality of NR base stations 360, also known as gNodeBs (gNBs), serving respective cells in the coverage area of the NR network 300. The gNBs 360 provide UEs 100 in the coverage area of the NR network 300 connection to the 5GC 300 and communicate with the UEs 100 according to the NR standard. In some implementations, the NG-RAN 350 may further comprise one or more LTE/NR base stations, also known as Next Generation eNBs (ng-eNBs) 370 providing the UEs 100 connection to the 5GC 310. The ng-eNBs 370 implement LTE for communication over the air interface with the UEs 100. Those skilled in the art will appreciate that while eNBs 260, gNBs 360 and ng-eNBS 370 are logically distinct, they can be co-located and/or share components.

The UEs 100 shown in Figures 1 comprise dual mode wireless devices capable of communicating with the eNBs 260 in the E-UTRAN 250 and the gNBs 360 or ng-eNBs 370 in the NG-RAN 350. For example, the UEs 100 may comprise cellular telephones, smart phones, laptop computers, notebook computers, tablets, machine-to-machine (M2M) devices (also known as machine type communication (MTC) devices), embedded devices, wireless sensors, or other types of wireless end user devices capable of communicating over wireless communication networks 10.

Figure 2 is a reference architecture for the EPC 210 in an LTE network 200. The EPC 210 comprises a serving gateway (SGW) 215, a packet data network gateway (PGW) 220, a mobility management entity (MME) 225, a Home Subscriber Server (HSS) 230 and a Policy and Charging Rules Function (PCRF) 235. The PGW 220 includes a control plane part PGW-C and a user plane part PGW-U.

Figure 3 is a reference architecture for a 5GC 310 in a NR network 300. The 5GC 310 comprises a plurality of network functions (NFs), such as a user plane function (UPF) 315, an access and mobility management function (AMF) 320, a session management function (SMF) 325, a policy control function (PCF) 330, a unified data management (UDM) function 335, a authentication server function (AUSF) 340 and a network exposure function (NEF) 345. These NFs comprise logical entities that reside in one or more core network nodes, which may be implemented by one or more processors, hardware, firmware, or a combination thereof. The functions may reside in a single core network node, or may be distributed among two or more core network nodes.

In conventional wireless communication network, the various NFs (e.g., SMF 325, AMF 320, etc.) in the 5GC 310 communicate with one another over predefined interfaces. In the service-based architecture shown in Figure 3, instead of predefined interfaces between the control plane functions, the wireless communication network 10 uses a services model in which the NFs query a NF repository function (NRF) 348 or other NF discovery node to discover and communicate with each other.

During the initial roll-out of NR networks 300, service providers are likely to phase in NR systems gradually and leverage existing LTE networks 200 to provide service in areas where NR networks 300 do not provide coverage. Therefore, interworking protocols are needed to enable interworking between NR networks 300 and LTE networks 200 to provide services (e.g., voice communication) not supported by the NR network 300 in the area where the UE 100 is located. For example, the service provider may not implement voice communications in the NR network 300 in some areas, so the UE 100 may need to switch to the LTE network 200 to accept or make a voice call. Also, a UE 100 may be configured for data communications over NR networks 300, but may not support voice communications over the NR network 300. In these scenarios, the UE 100 may need to fallback to an LTE network 200 in order to make or accept a voice call or other communication.

One approach to interworking is known as Evolved Packet System (EPS) fallback. EPS fallback is a procedure for triggering handover or redirect from a NR network to an LTE network towards an E-UTRA node connected to the EPS in scenarios where a LTE radio access network (RAN) is connected to an Evolved Packet Core (EPC) a communication is not supported by the 5G Core (5GC). For EPS fallback, a Next Generation RAN (NG RAN), is configured to handover/redirect the UE to the LTE RAN. Another approach to interworking is known as Radio Access Technology (RAT) fallback. RAT fallback is a procedure for triggering handover/redirect from a NR network to an LTE network towards an E-UTRA node connected a 5G Core (5GC) in scenarios where the LTE RAN is connected to communication is not supported by NR.

Following a EPS fallback or RAT fallback, the UE 100 is able to accept or make a voice call or other communication not otherwise supported by the NR network 300 or NR-capable UE 100. When the communication terminates, it may be desirable for the UE 100 to return to the NR network 300. However, there are currently no mechanisms in place to ensure that the UE 100 returns to the NR network 300 when a communication that precipitated the EPS fallback or RAT fallback terminates. The present disclosure provides both a UE-based solution and network- based solutions to enable the UE 100 to return to the NR network 300 once the communication that precipitated the EPS fallback or RAT fallback terminates.

UE-Based Solution

In this case, the UE 100 supports dual-registration in EPS/MME and 5GS/AMF (e.g., the UE 100 is simultaneously connected to a node such as a gNB 360 of ng-eNB 370 in the NG-RAN 350 and a node such as an eNB 260 in the E-UTRAN 250) and the communication network 10 supports common user plane and Internet Protocol (IP) address preservation. As a fallback-like procedure (e.g., when the UE 100 wishes to make a communication such as a voice call that is unsupported by the NG-RAN 350), the UE 100 decides to move a Packet Data Network (PDN) connection from an LTE network 200 to a NR network 300 and a Packet Data Unit (PDU) session from the NR network 300 to the LTE network 200. If the UE 100 has moved the PDU session supporting a IP Multimedia Subsystem (IMS) APN to the LTE network 200 for the purpose of originating or terminating a communication such as a voice call, the UE 100 moves the PDN connection supporting the IP Multimedia Subsystem (IMS) Access Point Name (APN) to 5GS after the last communication has been cleared, possibly after a certain time to avoid too frequent access changes.

Network-Based Solution - Overview

Two network-based solutions are provided for EPS fallback and RAT fallback respectively.

In the case of EPS fallback, the NG-RAN 350 indicates to the AMF 320 that handover is due to EPS fallback (e.g., because a QoS flow is being setup for a voice communication and not due to bad radio conditions). The AMF 320 indicates to MME 225 that the handover to E-UTRAN 250 was performed as a result of EPS fallback. The MME 225 indicates to E-UTRAN 250 that the handover to E-UTRAN 250 was performed as a result of EPS fallback. E-UTRAN 250 may use the indication to determine which of the existing mechanisms should be used to move the UE 100 to NG-RAN 350 once the QoS Class Identifer (QCI) =1 bearer has been released. If different Public Land Mobile Networks (PLMNs) are used by NG-RAN 350 and E-UTRAN 250, the MME 225 may get the PLMN Identifer (PLMN ID) for the last used NG RAN 350 from AMF 320 and the MME 225 may indicate the last used NG-RAN 350 PLMN ID to the E-UTRAN 250. The E UTRAN 250 shall take the last used NG-RAN 350 into account when selecting the target cell in packet-switched (PS) handover to the NG-RAN 350, or when selecting the dedicated target frequency list for idle mode mobility to the NG-RAN 350.

In the case of RAT fallback, the gNB 360 or other NR node indicates to the AMF 320 that the handover is due to RAT fallback (e.g., because a QoS flow is being setup and not due to bad radio conditions). The AMF 320 should indicate to NG-RAN 350 E-UTRA node (ng-eNB 260) that the handover to E-UTRA was performed as a result of RAT fallback. The NG-RAN Evolved Universal Terrestrial Radio Access (E-UTRA) node (ng-eNB 260) may use the indication to determine which of the existing mechanisms should be used to move the UE 100 to the NG-RAN 350 once the QoS flow has been released. If different PLMNs are used by NG-RAN 350 and E- UTRAN 250, the AMF 320 may indicate the PLMN ID for the last used NG-RAN 350 to E-UTRAN 250. The E-UTRAN 250 shall take the last used NG-RAN 350 into account when selecting the target cell in PS handover to NG-RAN 350, or when selecting the dedicated target frequency list for idle mode mobility to NG-RAN 350.

In addition to determining that the UE 100 should be moved back to NG-RAN 350 after the call has been completed (e.g., the QCI=1 bearer has been released), the involved nodes can use both the RAT fallback and the EPS fallback indicators for KPI, e.g., to differentiate, normal handover (HO) failure from EPS/RAT fallback, and call setup failure on E-UTRAN 250 from EPS/RAT fallback. The fallback indicator can in some examples disclosed herein used to inform the target MME 225 and RAN (e.g., E-UTRAN 250) that the UE 100 has been moved to the target RAN, not because of bad radio conditions in the source or overload in the source, but due to the need to establish a communication such as a voice call. The target MME 225/RAN can use this information to decide that the UE 100 should be moved back to NG-RAN 350 once the communication has been terminated.

In addition, in some embodiments, the fallback indicator can be used as KPI to differentiate the fallback case from other mobility cases, and to differentiate error or failure cases. In some examples, the indicator is only of relevance during the fallback from NG-RAN 350 to E- UTRAN 250 and when the UE 100 is actually on E-UTRAN 250.

EPS Fallback Scenario

Figures 4A and 4B illustrate an exemplary call flow for EPS fallback. The procedure, illustrated in Figures 4A and 4B involves a handover to EPC 210 and setup of default EPS bearer and dedicated bearers for guaranteed bit rate (GBR) QoS flows in EPC 310 in steps 1 -16 and reactivation, if required, of dedicated EPS bearers for non-GBR QoS flows in step 17. This procedure can be triggered, for example, due to new radio conditions, load balancing or due to specific service, e.g., in the presence of QoS flow for voice, the source NG-RAN 350 may trigger handover to EPC.

UE 100 (or, in other embodiments, wireless device) has one or more ongoing PDU sessions each including one or more QoS flows. During PDU session establishment and GBR QoS flow establishment, PGW-C+SMF performs EPS QoS mappings and allocates TFT with the Policy Control and Charging (PCC) rules obtained from the PCF+PCRF if PCC is deployed, otherwise EPS QoS mappings and Traffic Flow Template (TFT) allocation are executed by the PGW-C+SMF locally. EPS bearer identification (Bearer IDs) are allocated by the serving AMF 320 requested by the SMF 325 if the SMF 325 determines that EPS bearer ID(s) needs to be assigned to the QoS flow(s). For each PDU Session, EPS bearer ID(s) are allocated to the default EPS bearer which non GRB flows are mapped to, and allocated to dedicated bearers which the GBR flows that are mapped to in EPC. The EPS Bearer ID(s) for these bearer are provided to the UE 100 and PGW-C+SMF by AMF 320. The UE 100 is also provided with the mapped QoS parameters. The mapped EPS QoS parameters may be provided to PGW-C+SMF by the PCF+PCRF, if PCC is deployed. Steps of the example handover process are described below:

1. The NG-RAN 350 decides that the UE 100 should be handed over to the E- UTRAN 250. The NG-RAN 350 sends a Handover Required (Target eNB Identifier (ID), Source- To-Target transparent container, EPS fallback indicator) message to the AMF 320. That is, the Handover Required message contains, is accompanied by, or is associated with indicators that indicate a Target eNB ID, Source-To-Target transparent container, and EPS fallback indicator. The EPS fallback indicator may indicate, for example, that the handover is required because of fallback instead of, for example, any other condition such as poor radio conditions.

2. The AMF 320 determines from the 'target eNB identifier' information element (IE) that the type of handover is a handover to E-UTRAN 250. The AMF 320 requests the PGW- C+SMF to provide session management (SM) context that also includes the mapped EPS bearer contexts. This step is performed with all PGW-C+SMFs allocated to the UE 100. In a roaming scenario, the UE 100's SM EPS contexts are obtained from the Virtual SMF (v-SMF).

3. The AMF 320 selects an MME 225 and sends a Relocation Request (Target E- UTRAN Node ID, Source-to-Target transparent container, mapped MM and SM EPS UE 100 context (default and dedicated GBR bearers), EPS fallback indicator, NG-RAN 350 PLMN ID) message. The NG-RAN 350 PLMN ID may be, for example, the ID of the PLMN in the NG-RAN 350 to which the UE 100 is connected before handover to the E-UTRAN 250. The SGW 215 address and TEID for both the control plane or EPS bearers in the message are such that the target MME 225 selects a new SGW 215.

4. The MME 225 selects the SGW 215 and sends a Create Session Request message for each PDN connection to the SGW 215.

5. The SGW 215 allocates its local resources and returns them in a Create Session Response message to the MME 225.

6. The MME 225 requests the target eNodeB 260 to establish the bearer(s) by sending the message Handover Request message. This message also contains a list of EPS Bearer IDs that need to be setup and EPS fallback indicator and PLMN ID for the NG-RAN 350.

7. The target eNB 260 allocates the requested resources and returns the applicable parameters to the target MME 225 in the message Handover Request Acknowledge (Target-to- Source transparent container, EPS Bearers setup list, EPS Bearers failed to setup list).

8. If the MME 225 decides that indirect forwarding applies, it sends a Create Indirect Data Forwarding Tunnel Request message (Target eNB Address, TEID(s) for downlink (DL) data forwarding) to the SGW 215. The SGW 215 returns a Create Indirect Data Forwarding Tunnel Response (Cause, SGW 215 Address(es) and SGW DL TEID(s) for data forwarding) message to the target MME 225.

9. The MME 225 sends the message Relocation Response (Cause, List of Set Up Radio Access Bearers (RABs), EPS Bearers setup list, MME Tunnel Endpoint Identifier (TEID) for Control Plane, RAN Cause, MME Address for Control Plane, Target-to-Source transparent container, Address(es) and TEID(s) for data forwarding). 10. If indirect forwarding applies, the AMF 320 forwards to the PGW-C+SMF the information related to data forwarding to the SGW 215. The PGW-C+SMF returns a Create Indirect Data Forwarding Tunnel Response.

1 1 . The AMF 320 sends the Handover Command to the source NG-RAN 350. The source NG-RAN 350 commands the UE 100 to handover to the target access network by sending the HO Command. This message includes a transparent container including radio aspect parameters that the target eNB 260 has set-up in the preparation phase. The UE 100 correlates the ongoing QoS flows with the indicated EPS Bearer IDs to be setup in the HO command. UE 100 locally deletes the QoS flows that do not have an EPS bearer ID assigned.

12. When the UE 100 has successfully accessed the target eNodeB 260, the target eNodeB 260 informs the target MME 225 by sending the message Handover Notify.

13. The target MME 225 informs the SGW 215 that the MME 225 is responsible for all the bearers the UE 100 have established by sending the Modify Bearer Request message for each PDN connection.

The target MME 225 releases the non-accepted EPS Bearer contexts by triggering the Bearer context deactivation procedure. If the SGW 215 receives a DL packet for a non- accepted bearer, the SGW 215 drops the DL packet and does not send a Downlink Data Notification to the SGSN.

14. The SGW 215 informs the PGW-C+SMF of the relocation by sending the Modify Bearer Request message for each PDN connection. The PGW locally deletes the QoS flows that do not have an EPS bearer ID assigned. Due to the "match all" filter in the default QoS flow, the PGW maps the IP flows of the deleted QoS flows to the default QoS flow.

15. The PGW-C+SMF acknowledges the Modify Bearer Request. At this stage the User Plane path is established for the default bearer and the dedicated GBR bearers between the UE 100, target eNodeB 260, SGW 215 and the PGW+SMF.

16. The SGW 215 acknowledges the User Plane switch to the MME 225 via the message Modify Bearer Response.

17. The PGW-C+SMF initiates dedicated bearer activation procedure for non-GBR QoS flows by mapping the parameters of the non-GBR flows to EPC QoS parameters. This setup may be triggered by the PCRF+PCF which may also provide the mapped QoS parameters, if PCC is deployed. This procedure is specified in TS 23.401 [13], clause 5.4.1 . RAT fallback Scenario

Figure 5 illustrates an exemplary call flow for RAT fallback.

1. The Source RAN (S-RAN) 350 to Source AMF (S-AMF) 320: Handover Required (Target ID, Source-to-Target transparent container, SM N2 info list, PDU Session IDs, RAT fallback indicator).

The RAT fallback indicator may also be included in one of the existing lEs). The Source- to-Target transparent container includes RAN information created by S-RAN to be used by T- RAN, and is transparent to 5GC 310.

All PDU Sessions handled by S-RAN 350 (i.e. all existing PDU Sessions with active UP connections) shall be included in the Handover Required message, indicating which of those PDU Session(s) are requested by S-RAN 350 to handover. The SM N2 info also includes Direct Forwarding Path Availability, and which QoS flows are subject to data forwarding.

Direct Forwarding Path Availability indicates whether direct forwarding is available from the S-RAN 350 to the Target RAN (T-RAN). This indication from S-RAN 350 can be based on e.g., the presence of IP connectivity and security association (s) between the S-RAN 350 and the T-RAN.

2. [Conditional] S-AMF 320 to Target AMF (T-AMF) 320: Forward Relocation Request (SUPI, Target ID, Source-to-Target transparent container, SM N2 info list, PDU Session IDs, RAT fallback indicator).

The RAT fallback indicator may be, for example, an indication that the handover is required because of fallback and not some other condition, such as for example poor radio conditions. When the S-AMF 320 can't serve the serve the UE 100 anymore, the S-AMF 320 selects the T-AMF 320 as described in clause 6.4.5 on "AMF 320 Selection Function" in TS 23.501. The S-AMF 320 initiates Handover resource allocation procedure by sending a Forward Relocation Request message to the T-AMF 320. When the S-AMF 320 can still serve the UE 100, this step and step 12 are not needed.

3. [Conditional] T-AMF 320 to SMF 325: PDU Handover Request (PDU Session ID, Target ID). For each PDU Session indicated by S-RAN 350 as an N2 Handover candidate, the AMF 320 sends PDU Handover Request per PDU Session to the associated SMF. The PDU Session ID indicates a PDU Session candidate for N2 Handover.

4. [Conditional] Based on the new location info, SMF 325 checks if N2 Handover for the indicated PDU Session can be accepted. The SMF 325 checks also the UPF Selection Criteria according to clause 6.3.3 of TS 23.501. If UE 100 has moved out of the service area of the UPF 315 connecting to RAN, SMF 325 selects a new intermediate UPF 315. If the PDU Session corresponds to a Local Area Data Network (LADN) and the UE 100 is outside the area of availability of the LADN, then the SMF 325 moves to step 5c.

5a. [Conditional] SMF 325 to T-UPF (intermediate) 315: N4 Session Establishment Request

If the SMF 325 selects a new intermediate UPF 315, target UPF (T-UPF) 315, for the PDU Session and if CN Tunnel Info is allocated by the T-UPF 315, an N4 Session Establishment Request message is sent to the T-UPF 315, providing packet detection, enforcement and reporting rules to be installed on the T-UPF 315. The PDU Session anchor tunnel info for this PDU Session is also provided to the T-UPF 315.

5b. T-UPF (intermediate) 315 to SMF 325: N4 Session Establishment Response.

The T-UPF 315 sends an N4 Session Establishment Response message to the SMF 325 with CN DL tunnel info and UL Tunnel info (i.e. N3 tunnel info). The SMF 325 starts a timer. If steps 5a and 5b are performed for a PDU Session, steps 5c and 5d are skipped.

5c, d. [Conditional] SMF 325 to S-UPF 315: N4 Session Modification Request/Response.

If the PDU Session corresponds to a LADN and the UE 100 is outside the area of availability of the LADN, the SMF 325 updates the N4 session of the UPF 315(s) corresponding to the PDU Session to deactivate the corresponding UP connection. The SMF 325 may notify the UPF 315 that originated the Data Notification to discard downlink data for the PDU Sessions and/or to not provide further Data Notification messages.

6. SMF 325 to T-AMF 320: PDU Handover Response (PDU Session ID, SM N2 info).

If N2 handover for the PDU Session is accepted, the SMF 325 includes the result in SM N2 info sent, transparently for the AMF 320, to the T-RAN including in the SM N2 info the PDU Session ID, N3 UP address and Tunnel ID of UPF 315, and QoS parameters.

If N2 handover for the PDU Session is not accepted as described in step 3, the SMF 325 does not include an SM N2 info regarding the PDU Session to avoid establishment of radio resources at the target RAN.

The SMF 325 sends an Nsmf_PDUSession_UpdateSMcontext response without including the CN tunnel information to the AMF 320 for the PDU Session(s) which is to be released, and then release the PDU Session(s) in a separate procedure as defined in clause 4.3.4.

7. AMF 320 supervises the PDU Handover Response messages from the involved SMF 325s. The lowest value of the Max delay indications for the PDU Sessions that are candidates for handover gives the maximum time AMF 320 may wait for PDU Handover Response messages before continuing with the N2 Handover procedure. At expiry of the maximum wait time or when all PDU Handover Response messages are received, AMF 320 continues with the N2 Handover procedure (Handover Request message in step 8). The delay value for each PDU Session is locally configured in the AMF 320 and implementation specific.

8. T-AMF 320 to T-RAN 350: Handover Request (Source-to-Target transparent container, MM N2 info, SM N2 info list, RAT fallback indicator).

T-AMF 320 determines T-RAN based on Target ID. T-AMF 320 may allocate a 5G-GUTI valid for the UE 100 in the AMF 320 and target TAI.

Source-to-Target transparent container is forwarded as received from S-RAN 350. Mobility Management (MM) N2 info includes e.g., security information and Handover Restriction List.

SM N2 info list includes SM N2 info received from SMF 325s in the PDU Handover Response messages received within allowed max delay supervised by the T-AMF 320 mentioned in step 7. SM N2 info also indicates which QoS flows are subject to data forwarding.

9. T-RAN 350 to T-AMF 320: Handover Request Acknowledge (Target to Source transparent container, SM N2 response list, PDU Sessions failed to be setup list, T-RAN SM N3 forwarding info list).

Target to Source transparent container includes a UE 100 container with an access stratum part and a NAS part. The UE 100 container is sent transparently via T-AMF 320, S-AMF 320 and S-RAN 350 to the UE 100.

The information provided to the S-RAN 350 also contains a list of PDU Session IDs indicating PDU Sessions failed to be setup and reason for failure (SMF 325 decision, SMF 325 response too late, or T-RAN decision).

The SM N2 response list includes, per each received SM N2 info and by SMF 325 accepted PDU Session for N2 Handover, a PDU Session ID and an SM N2 response indicating the PDU Session ID and if T-RAN accepted the N2 Handover request for the PDU Session. For each by T-RAN accepted PDU Session for N2 Handover, the SM N2 response includes N3 UP address and Tunnel ID of T-RAN.

The T-RAN SM N3 forwarding info list includes, per each PDU Session accepted by T- RAN and has at least one QoS flow subject for data forwarding, N3 UP address and Tunnel ID of T-RAN for receiving forwarded data if necessary.

10. [Conditional] T-AMF 320 to SMF 325: PDU Handover Cancel (PDU Session ID).

When a PDU Handover Response message arriving too late (see step 7) , or the PDU Session with SMF 325 involvement is not accepted by T-RAN, this message is indicated to the corresponding SMF 325 allowing the SMF 325 to deallocate a possibly allocated N3 UP address and Tunnel ID of the selected UPF 315. A PDU Session handled by that SMF 325 is considered deactivated and handover attempt is terminated for that PDU Session.

l l a. AMF 320 to SMF 325: Modify PDU Request (PDU Session ID, SM N2 response, T-RAN SM N3 forwarding info list).

For each SM N2 response received from the T-RAN (included in SM N2 response list), AMF 320 sends the received SM N2 response to the SMF 325 indicated by the respective PDU Session ID.

If no new T-UPF 315 is selected, SMF 325 stores the N3 tunnel info of T-RAN from the SM N2 response if N2 handover is accepted by T-RAN.

l l b. [Conditional] SMF 325 to T-UPF 315: N4 Session Modification Request (T-RAN SM N3 forwarding info list)

If indirect forwarding applies and the UPF 315 is relocated the SMF 325 selects a T-UPF 315 and sends an N4 Session Modification Request message to the T-UPF 315. If the UPF 315 is not relocated, indirect forwarding may be set up in step 1 1 d and 11 e below.

Indirect forwarding may be performed via a UPF 315 which is different from the T-UPF

315.

11 c. [Conditional] T-UPF 315 to SMF 325: N4 Session Modification Response (T-UPF SM N3 forwarding info list)

The T-UPF 315 allocates tunnel information and returns an N4 Session Modification Response message to the SMF 325. The T-UPF 315 SM N3 forwarding info list includes T-UPF 315 N3 address, T-UPF 315 N3 Tunnel identifiers for forwarding data

11 d . [Conditional] SMF to S-UPF: N4 Session Modification Request (T-RAN SM N3 forwarding info list)

If indirect forwarding applies the SMF 325 sends an N4 Session Establishment Request message to the S-UPF 315. If the UPF 315 is relocated, this message includes the T-UPF 315 SM N3 forwarding info list. If the UPF 315 is not relocated, this message includes the T-RAN SM N3 forwarding info list. Indirect forwarding may be performed via a UPF 315 which is different from the S-UPF 315.

11 e. [Conditional] S-UPF315 to SMF 325: N4 Session Modification Response (S-UPF 315 SM N3 forwarding info list)

The S-UPF 315 allocates tunnel information and returns an N4 Session establishment Response message to the SMF 325. The S-UPF SM N3 forwarding info list includes S-UPF N3 address, S-UPF 315 N3 Tunnel identifiers for forwarding data 11 f . SMF 325 to T-AMF 320: Modify PDU Response (S-UPF SM N3 forwarding info list)

The SMF 325 sends Modify PDU Response message per PDU Session to T-AMF 320. The SMF 325 starts an indirect data forwarding timer, to be used to release the resource of indirect data forwarding tunnel.

12. [Conditional] T-AMF 320 to S-AMF 320: Forward Relocation Response (Target to Source transparent container, PDU Sessions failed to be setup list, S-UPF SM N3 forwarding info list)

AMF 320 supervises the Modify PDU Response message from the involved SMF 325s. At expiry of the maximum wait time or when all Modify PDU Response messages are received, T-AMF 320 sends Forward Relocation Response to S-AMF 320. The Target to Source transport container is received from the T-RAN. The S-UPF 315 SM N3 forwarding info list is received from S-UPF 315.

Return to NG-RAN

One example to move the UE 100 back from E-UTRAN 250 to NG-RAN 350 is to trigger the handover procedure once the QoS flow for voice has been released (or, in other embodiments, when a communication carried out by the UE 100/wireless device that is unsupported by the NG-RAN 350 has been terminated).

The following example call flow illustrated in Figure 6 below shows the preparation phase:

This procedure applies to the Non-Roaming (TS 23.501 [2] Figure 4.3.1-1), Home-routed roaming (TS 23.501 [2] Figure 4.3.2-1) and Local Breakout roaming Local Breakout (TS 23.501 [2] Figure 4.3.2-2) cases. For non-roaming scenario, v-SMF, v-UPF and v-PCF+v- PCRF are not present. For home-routed roaming scenario, the SMF+PGW-C and UPF+PGW-U are in the HPLMN. v-PCF+v-PCRF are not present. For local breakout roaming scenario, v-SMF and v-UPF are not present. SMF+PGW-C and UPF+PGW-U are in the VPLMN. In local-breakout roaming case, the v-PCF+v-PCRF forwards messages between the SMF+PGW-C and the h- PCF+h-PCRF.

1. The source E-UTRAN 250 decides that the UE 100 should be handed over to the NG-RAN 350, e.g., if the source E-UTRAN 250 has received the EPS fallback indicator and the QCI=1 bearer was released.

2. The E-UTRAN 250 sends a Handover Required (Target NG-RAN 350 Node ID, Source-to-Target transparent container) message to the MME 225.

3. The MME 225 selects the target AMF 320 and sends a Forward Relocation Request (Target NG-RAN 350 Node ID, Source-to-Target transparent container, EPS MM context, EPS Bearer context(s)) message to the selected AMF 320. The AMF 320 converts the received EPS MM context into the 5GS MM context. The MME 225 UE 100 context includes IMSI, ME Identity, UE 100 security context, UE 100 Network Capability, and EPS Bearer context(s). An EPS Bearer context includes the common SMF + PGW-C address and V-CN Tunnel Info at the UPF + PGW-U for uplink traffic, and APN.

4. The AMF 320 sends a PDU Handover Request (PDN Connection, AMF 320 ID) message to the selected SMF. The PDN Connection provides the common SMF + PGW-C address. For home-routed roaming scenario, the v-SMF selects the SMF + PGW-C using the PDN Connection.

5. If dynamic PCC is deployed, the SMF may initiate PDU Session Modification towards the h-PCF + h-PCRF to obtain the 5GS PCC Rules for the PDU Session. The h-PCF + h-PCRF does not apply the 5GS PCC Rules for the PDU Session.

6. The SMF+PGW-C modifies the PGW-U+UPF.

7. The SMF + PGW-C sends a PDU Session Modification Response (PDU Session ID, QoS Rules, EPS Bearer Setup List, SSC Mode, H-CN Tunnel-Info) to the AMF 320.

8. For home-routed roaming scenario only: The v-SMF selects a v-UPF and initiates an N4 Session Establishment procedure with the selected v-UPF. The v-SMF provides the v- UPF with packet detection, enforcement and reporting rules to be installed on the UPF for this PDU Session, including H-CN Tunnel Info. If CN Tunnel Info is allocated by the SMF, the V-CN Tunnel Info is provided to the v-UPF in this step. The v-UPF acknowledges by sending an N4 Session Establishment Response message. If CN Tunnel Info is allocated by the UPF, the V-CN Tunnel info is provided to the v-SMF in this step.

9. The AMF 320 sends a Handover Request (Source-to-Target transparent container, N2 SM Information (PDU Session ID, QoS Profile(s), V-CN Tunnel Info)) message to the NG-RAN 350.

10. The NG-RAN 350 sends a Handover Request Acknowledge (Target to Source transparent container, N2 SM response (PDU Session ID, list of accepted QoS flows and (R)AN Tunnel Info), N2 SM Information for PDU Forwarding (PDU Session ID, N3 Tunnel Info for PDU Forwarding)) message to the AMF 320.

1 1 . The AMF 320 sends a Modify PDU Session Request (PDU Session ID, N2 SM response (list of accepted QoS flows and (R)AN Tunnel Info), (N2 SM Information for PDU Forwarding (PDU Session ID, N3 Tunnel Info for PDU Forwarding)) message to the SMF for updating N3 tunnel information.

12. SMF+PGW-C to AMF 320: Modify PDU Response (PDU Session ID, EPS Bearer Setup List). This message is sent for each received Modify PDU Request message. SMF+PGW- C performs preparations for N2 Handover by indicating N3 UP address and Tunnel ID of NG- RAN 350 to the UPF if N2 Handover is accepted by NG-RAN 350. If N2 Handover is not accepted by NG-RAN 350, SMF+PGW-C deallocates N3 UP address and Tunnel ID of the selected UPF. The EPS Bearer Setup list is a list of EPS bearer Identifiers successfully handover to 5GC, which is generated based on the list of accepted QoS flows.

13. If indirect forwarding applies, the MME 225 sends the Create Indirect Data Forwarding Tunnel Request/Response.

14. The AMF 320 sends the message Forward Relocation Response (Cause, Target to Source transparent container, SGW 215 change indication, EPS Bearer Setup List, AMF 320 Tunnel Endpoint Identifier for Control Plane, Addresses and TEIDs). The EPS Bearer Setup list is the combination of EPS Bearer Setup list from different SMF+PGW-C(s).

In other examples, where a wireless device (e.g., UE 100) is redirected to network such as E-UTRAN 250 from a NG-RAN 350, instead of being handed over, a redirection indicator (similar or identical to the fallback indicator in form and/or use in some examples) can be used to indicate to the target RAN that the redirection was due to e.g., the NG-RAN 350 not supporting a communication that the wireless device wishes to be involved with. In some examples, the redirection indicator can be used to determine that the wireless device should be redirected back to the NG-RAN 350 upon completion or termination of the communication.

Figure 7A illustrates an exemplary method 400 implemented by UE 100 or other wireless device for handing over or redirecting from an E-UTRAN 250 or NG-RAN 350 to a NG-RAN 350 following termination of a voice call or other communication the precipitated by an EPS fallback or RAT fallback. The UE 100 with a first connection to an APN over a source RAN (e.g., NG- RAN 350) optionally determines that a communication by the UE 100 is to be commenced (block 410). In response to determining that a communication is to be commenced, the UE 100 moves the first connection from a source RAN to a target RAN (e.g., E-UTRAN 250 or NG-RAN 350) (block 420). The communication may comprise, for example, a voice communication or other communication that is not supported by NR network 300. After moving the first connection to the target RAN, the UE 100 commences the communication over the target RAN (block 430). In response to termination of the communication, the UE 100 moves the first connection or a second connection from the target RAN to the source RAN (block 440).

Some embodiments of the method 400 further comprise, in response to determining that a communication by the wireless device is to be commenced, moving a second connection from the target RAN to the source RAN.

In some embodiments of the method 400, the second connection comprises a PDN connection on a E-UTRAN 250 and/or a PDU session on a NG-RAN 350.

In some embodiments of the method 400, the first connection comprises a PDU session on a NG-RAN 350 and/or a PDN connection on the E-UTRAN 250. In some embodiments of the method 400, the communication comprises a voice call

In some embodiments of the method 400, the communication is unsupported by the source RAN 350.

In some embodiments of the method 400, the wireless device is connected simultaneously to the source RAN and the target RAN.

Some embodiments of the method 400 further comprise, in response to determining that the communication has been terminated, moving the first connection to the source RAN from the target RAN.

Some embodiments of the method 400 further comprise moving the first connection to the source RAN from the target RAN after a predetermined time period following commencement of the communication or moving the first connection to the target RAN.

Figure 7B illustrates an exemplary method 450 implemented by UE 100 for handover or redirection. The UE 100 with a first connection to an APN over a source RAN (e.g., NG-RAN 350) optionally determines that a communication by the UE 100 is to be commenced (block 460). In response to determining that a communication is to be commenced, the UE 100 moves the first connection from the source RAN to a target RAN (e.g., E-UTRAN 250 or NG RAN 350) on which the communication is supported (block 470). The communication may comprise, for example, a voice communication or other communication that is not supported by NR network 300. In response to moving the first connection, the UE 100 moves a second connection from the target RAN to the source RAN.

Figure 8 illustrates a method 500 implemented by a network node for handover or redirection of a wireless device. The network node determines that a UE 100 or other wireless device connected to a second RAN (e.g., E-UTRAN 250 or NG-RAN 350) was previously connected to a first RAN (e.g., NG-RAN 350)(block 510). In response to determining that the wireless device has completed a communication through the second RAN, the network node causes the wireless device to handover or be redirected to the NG-RAN 350 (block 520).

In some embodiments of the method 500, determining that a wireless device connected to a second RAN was previously connected to a first RAN comprises determining that the wireless device is connected to the E-UTRAN following a fallback or redirect procedure from the NG-RAN.

In some embodiments of the method 500, the fallback or redirect procedure comprises a RAT fallback procedure or an EPS fallback procedure.

In some embodiments of the method 500, determining that a wireless device connected to a second RAN was previously connected to a first RAN comprises receiving information that the wireless device was previously connected to the first RAN. In some embodiments of the method 500, the information is received from the first RAN, a gNB or eNB in the first RAN, an AMF in the first RAN, a MME in an EPC, a node in the first RAN or a node in the second RAN.

In some embodiments of the method 500, the information comprises a fallback indicator or redirection indicator.

In some embodiments of the method 500, the fallback indicator or redirection indicator is received in a Relocation Request message or a handover request message.

In some embodiments of the method 500, determining that a wireless device connected to a second RAN was previously connected to a first RAN comprises determining an identifier of a network or a network node in the first RAN to which the wireless device was previously connected.

In some embodiments of the method 500, causing the wireless device to handover or be redirected to the first RAN comprises causing the handover or redirection based on the identifier.

In some embodiments of the method 500, selecting a handover or redirect target cell based on the indicator or selecting a dedicated handover or redirect target frequency list based on the identifier.

In some embodiments of the method 500, the identifier comprises a PLMN ID.

In some embodiments of the method 500, causing the wireless device to handover or be redirected to the first RAN comprises causing handover or redirection to the network or the network node in the first RAN to which the wireless device was previously connected.

In some embodiments of the method 500, the identifier is received in a Relocation Request message or a handover request message.

Some embodiments of the method 500 further comprise determining that the wireless device has completed the communication through the second RAN.

In some embodiments of the method 500, wherein the second RAN comprises an E- UTRAN 250 and wherein determining that the wireless device has completed the communication through the second RAN comprises determining the absence of a radio access bearer or bearer with QCI=1.

In some embodiments of the method 500, causing the wireless device to handover or be redirected to the first RAN comprises causing handover or redirection to the same network or node in the first RAN to which the wireless device was previously connected.

In some embodiments of the method 500, causing the wireless device to handover or be redirected to the first RAN causing handover to a PLMN to which the wireless device was previously connected. In some embodiments of the method 500, the communication through the second RAN comprises a voice call.

In some embodiments of the method 500, the network node comprises a base station in the second RAN of first RAN. For example, the base station may comprise second RAN node (e.g., eNB 260 or ng-eNB 370) or first RAN node.

In some embodiments of the method 500, the network node comprises a AMF, MME or other core network node.

In some embodiments of the method 500, determining that a wireless device connected to a second RAN was previously connected to a first RAN comprises determining that the wireless device was handed over to the second RAN to begin the communication.

In some embodiments of the method 500, determining that the wireless device was handed over or redirected to the second RAN to begin the communication comprises receiving an indication from the first RAN.

In some embodiments of the method 500, causing the wireless device to handover or be redirected to the first RAN comprises indicating to a node in the second RAN that the wireless device was connected to a node in the first RAN.

Figure 9 illustrates an exemplary UE 100 in accordance with an embodiment configured to perform the method of Figured 7A, the method of Figure 7B, or both. The UE 100 comprises one or more antennas 1 10, an interworking module 120, a first communication module 130, and a second communication module 140. The modules 120 - 140 can be implemented by hardware and/or by software code that is executed by a processor or processing circuit. The interworking module 120 is configured move a first connection from a source RAN (e.g., NG-RAN 350) to a target RAN (e.g, E-UTRAN 250 or NG-RAN 350) in response to determining that a communication is to be commenced. In some embodiments, the interworking module 120 is further configured move the first connection or a second connection from the target RAN to the source RAN in response to determining that the communication is terminated as shown in Figure 7A. In other embodiments, the interworking module is configured to move a second connection from the target RAN to the source RAN in response to moving the first connection as shown in Figure 7B. The first communication module 130 is configured for communication over the NG- RAN 350. The second communication module 140 is configured for communication over the E- UTRAN 250.

Figure 10 illustrates an exemplary network node 150 in accordance with an embodiment. Network node 150 is configured to perform the method 500 shown in Figure 8. The network node 150 comprises an interworking module 160, and a communication module 170. The modules 160 and 170 can be implemented by hardware and/or by software code that is executed by a processor or processing circuit. In some embodiments, the network node 150 may comprise a virtual network function (VNF) implemented in a virtual machine (VM). The interworking module 160 is configured to determine that a UE 100 or other wireless device connected to a second RAN (e.g., E-UTRAN 250 or NG-RAN 350) was previously connected to a first RAN (e.g., NG- RAN 350). The interworking module 160 is further configured to cause the wireless device to handover or be redirected to the first RAN in response to determining that the wireless device has completed a communication through the first RAN. For example, the interworking module 160 may be configured to signal to the second RAN that a handover to the first RAN should be performed. The communication module 170 enables the interworking module 160 to communicate with interworking modules in other network nodes. In some implementations, the network node 150 may comprises an LTE base station or NR base station. In other embodiments, the network node may comprise a core network node.

Figure 1 1 illustrates the main functional components of a UE 600 configured to implement the method 400 of Figure 7. The UE 600 comprises one or more antennas 610, an interface circuit 620, a processing circuit 650, and memory 680.

The interface circuit 620 comprises RF circuitry for communicating over a wireless channel with the base station 30. The RF circuitry comprises a transmitter 625 and receiver 630 coupled to the antennas 610. The transmitter 625 and receiver 630 are configured to communicate with eNBs 260 or ng-eNBs 370 according to the LTE standard and with gNBs 360 according to the NR standards.

The processing circuit 640 controls the overall operation of the UE 600 and processes the signals transmitted to or received by the UE 600. Such processing includes transmit signal processing, receive signal processing, and signaling of control information. The processing circuit 640 may comprise one or more microprocessors, hardware, firmware, or a combination thereof. The processing circuit 640 can be configured to perform the method 500 shown in Figure 7.

Memory 690 comprises both volatile and non-volatile memory for storing computer program code and data needed by the processing circuit 640 for operation. Memory 690 may comprise any tangible, non-transitory computer-readable storage medium for storing data including electronic, magnetic, optical, electromagnetic, or semiconductor data storage. Memory 690 stores a computer program 695 comprising executable instructions that configure the processing circuit 640 to implement the method 400 shown in Figure 7. A computer program 690 in this regard may comprise one or more code modules corresponding to the means or units described above. In general, computer program instructions and configuration information are stored in a non-volatile memory, such as a ROM, erasable programmable read only memory (EPROM) or flash memory. Temporary data generated during operation may be stored in a volatile memory, such as a random access memory (RAM). In some embodiments, computer program 695 for configuring the processing circuit 640 as herein described may be stored in a removable memory, such as a portable compact disc, portable digital video disc, or other removable media. The computer program 695 may also be embodied in a carrier such as an electronic signal, optical signal, radio signal, or computer readable storage medium.

Figure 12 illustrates the main functional elements of a network node 700 configured implement the handover/redirection procedures as herein described. The network node 700 may comprise a core network node or, in some embodiments, a base station, such as a gNB. The network node 700 comprises an interface circuit 720, a processing circuit 730, and memory 790.

The interface circuit 720 comprises circuitry for coupling the network node 700 to a communication network 10 and enables the network node 700 to communicate over the communication network 10 with the base stations 30, 40 and other network nodes. In some embodiments, the interface circuit 720 also include RF circuitry for enabling communication with UEs 100.

The processing circuit 730 controls the overall operation of the network node 700 and processes the signals transmitted to or received by the network node 700. The processing circuit 730 may comprise one or more microprocessors, hardware, firmware, or a combination thereof. The processing circuit 730 can be configured to perform the method 500 shown in Figure 8.

Memory 790 comprises both volatile and non-volatile memory for storing computer program code and data needed by the processing circuit 730 for operation. Memory 790 may comprise any tangible, non-transitory computer-readable storage medium for storing data including electronic, magnetic, optical, electromagnetic, or semiconductor data storage. Memory 790 stores a computer program 795 comprising executable instructions that configure the processing circuit 730 to implement the method 500 shown in Figure 8. A computer program 790 in this regard may comprise one or more code modules corresponding to the means or units described above. In general, computer program instructions and configuration information are stored in a non-volatile memory, such as a ROM, erasable programmable read only memory (EPROM) or flash memory. Temporary data generated during operation may be stored in a volatile memory, such as a random access memory (RAM). In some embodiments, computer program 730 for configuring the processing circuit 730 as herein described may be stored in a removable memory, such as a portable compact disc, portable digital video disc, or other removable media. The computer program 795 may also be embodied in a carrier such as an electronic signal, optical signal, radio signal, or computer readable storage medium.

The handover and redirection techniques as herein described enable the UE to quickly move back to source RAN after EPS fallback or RAT fallback has been performed. Further, the techniques enable differentiation between handover for the purpose of enabling a communication from other failure cases. Although the subject matter described herein may be implemented in any appropriate type of system using any suitable components, the embodiments disclosed herein are described in relation to a wireless network, such as the example wireless network illustrated in Figure 13. For simplicity, the wireless network of Figure 13 only depicts network 1 106, network nodes 1160 and 1160b, and WDs 1110, 11 10b, and 1110c. In practice, a wireless network may further include any additional elements suitable to support communication between wireless devices or between a wireless device and another communication device, such as a landline telephone, a service provider, or any other network node or end device. Of the illustrated components, network node 1160 and wireless device (WD) 1 110 are depicted with additional detail. The wireless network may provide communication and other types of services to one or more wireless devices to facilitate the wireless devices’ access to and/or use of the services provided by, or via, the wireless network.

The wireless network may comprise and/or interface with any type of communication, telecommunication, data, cellular, and/or radio network or other similar type of system. In some embodiments, the wireless network may be configured to operate according to specific standards or other types of predefined rules or procedures. Thus, particular embodiments of the wireless network may implement communication standards, such as Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), and/or other suitable 2G, 3G, 4G, or 5G standards; wireless local area network (WLAN) standards, such as the IEEE 802.1 1 standards; and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave and/or ZigBee standards.

Network 1106 may comprise one or more backhaul networks, core networks, IP networks, public switched telephone networks (PSTNs), packet data networks, optical networks, wide-area networks (WANs), local area networks (LANs), wireless local area networks (WLANs), wired networks, wireless networks, metropolitan area networks, and other networks to enable communication between devices.

Network node 1160 and WD 1110 comprise various components described in more detail below. These components work together in order to provide network node and/or wireless device functionality, such as providing wireless connections in a wireless network. In different embodiments, the wireless network may comprise any number of wired or wireless networks, network nodes, base stations, controllers, wireless devices, relay stations, and/or any other components or systems that may facilitate or participate in the communication of data and/or signals whether via wired or wireless connections.

As used herein, network node refers to equipment capable, configured, arranged and/or operable to communicate directly or indirectly with a wireless device and/or with other network nodes or equipment in the wireless network to enable and/or provide wireless access to the wireless device and/or to perform other functions (e.g., administration) in the wireless network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)). Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and may then also be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units and/or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS). Yet further examples of network nodes include multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell/multicast coordination entities (MCEs), core network nodes (e.g., MSCs, MMEs), O&M nodes, OSS nodes, SON nodes, positioning nodes (e.g., E-SMLCs), and/or MDTs. As another example, a network node may be a virtual network node as described in more detail below. More generally, however, network nodes may represent any suitable device (or group of devices) capable, configured, arranged, and/or operable to enable and/or provide a wireless device with access to the wireless network or to provide some service to a wireless device that has accessed the wireless network.

In Figure 13, network node 1 160 includes processing circuitry 1 170, device readable medium 1 180, interface 1 190, auxiliary equipment 1 184, power source 1 186, power circuitry 1 187, and antenna 1 162. Although network node 1 160 illustrated in the example wireless network of Figure 13 may represent a device that includes the illustrated combination of hardware components, other embodiments may comprise network nodes with different combinations of components. It is to be understood that a network node comprises any suitable combination of hardware and/or software needed to perform the tasks, features, functions and methods disclosed herein. Moreover, while the components of network node 1 160 are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, a network node may comprise multiple different physical components that make up a single illustrated component (e.g., device readable medium 1 180 may comprise multiple separate hard drives as well as multiple RAM modules).

Similarly, network node 1 160 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which network node 1 160 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeB’s. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, network node 1 160 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate device readable medium 1 180 for the different RATs) and some components may be reused (e.g., the same antenna 1 162 may be shared by the RATs). Network node 1 160 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1 160, such as, for example, GSM, WCDMA, LTE, NR, WiFi, or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1 160.

Processing circuitry 1 170 is configured to perform any determining, calculating, or similar operations (e.g., certain obtaining operations) described herein as being provided by a network node. These operations performed by processing circuitry 1 170 may include processing information obtained by processing circuitry 1 170 by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination.

Processing circuitry 1 170 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other network node 1 160 components, such as device readable medium 1 180, network node 1 160 functionality. For example, processing circuitry 1 170 may execute instructions stored in device readable medium 1 180 or in memory within processing circuitry 1 170. Such functionality may include providing any of the various wireless features, functions, or benefits discussed herein. In some embodiments, processing circuitry 1 170 may include a system on a chip (SOC).

In some embodiments, processing circuitry 1 170 may include one or more of radio frequency (RF) transceiver circuitry 1 172 and baseband processing circuitry 1 174. In some embodiments, radio frequency (RF) transceiver circuitry 1 172 and baseband processing circuitry 1 174 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1 172 and baseband processing circuitry 1 174 may be on the same chip or set of chips, boards, or units

In certain embodiments, some or all of the functionality described herein as being provided by a network node, base station, eNB or other such network device may be performed by processing circuitry 1 170 executing instructions stored on device readable medium 1 180 or memory within processing circuitry 1 170. In alternative embodiments, some or all of the functionality may be provided by processing circuitry 1 170 without executing instructions stored on a separate or discrete device readable medium, such as in a hard-wired manner. In any of those embodiments, whether executing instructions stored on a device readable storage medium or not, processing circuitry 1 170 can be configured to perform the described functionality. The benefits provided by such functionality are not limited to processing circuitry 1 170 alone or to other components of network node 1 160, but are enjoyed by network node 1 160 as a whole, and/or by end users and the wireless network generally.

Device readable medium 1 180 may comprise any form of volatile or non-volatile computer readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device readable and/or computer-executable memory devices that store information, data, and/or instructions that may be used by processing circuitry 1 170. Device readable medium 1 180 may store any suitable instructions, data or information, including a computer program, software, an application including one or more of logic, rules, code, tables, etc. and/or other instructions capable of being executed by processing circuitry 1 170 and, utilized by network node 1 160. Device readable medium 1 180 may be used to store any calculations made by processing circuitry 1 170 and/or any data received via interface 1 190. In some embodiments, processing circuitry 1 170 and device readable medium 1 180 may be considered to be integrated.

Interface 1 190 is used in the wired or wireless communication of signalling and/or data between network node 1 160, network 1 106, and/or WDs 1 1 10. As illustrated, interface 1 190 comprises port(s)/terminal(s) 1 194 to send and receive data, for example to and from network 1 106 over a wired connection. Interface 1 190 also includes radio front end circuitry 1 192 that may be coupled to, or in certain embodiments a part of, antenna 1 162. Radio front end circuitry 1 192 comprises filters 1 198 and amplifiers 1 196. Radio front end circuitry 1 192 may be connected to antenna 1 162 and processing circuitry 1 170. Radio front end circuitry may be configured to condition signals communicated between antenna 1 162 and processing circuitry 1 170. Radio front end circuitry 1 192 may receive digital data that is to be sent out to other network nodes or WDs via a wireless connection. Radio front end circuitry 1 192 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1 198 and/or amplifiers 1 196. The radio signal may then be transmitted via antenna 1 162. Similarly, when receiving data, antenna 1 162 may collect radio signals which are then converted into digital data by radio front end circuitry 1 192. The digital data may be passed to processing circuitry 1170. In other embodiments, the interface may comprise different components and/or different combinations of components.

In certain alternative embodiments, network node 1160 may not include separate radio front end circuitry 1192, instead, processing circuitry 1170 may comprise radio front end circuitry and may be connected to antenna 1162 without separate radio front end circuitry 1192. Similarly, in some embodiments, all or some of RF transceiver circuitry 1172 may be considered a part of interface 1190. In still other embodiments, interface 1190 may include one or more ports or terminals 1194, radio front end circuitry 1192, and RF transceiver circuitry 1172, as part of a radio unit (not shown), and interface 1190 may communicate with baseband processing circuitry 1 174, which is part of a digital unit (not shown).

Antenna 1162 may include one or more antennas, or antenna arrays, configured to send and/or receive wireless signals. Antenna 1162 may be coupled to radio front end circuitry 1190 and may be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. In some embodiments, antenna 1 162 may comprise one or more omni-directional, sector or panel antennas operable to transmit/receive radio signals between, for example, 2 GHz and 66 GHz. An omni-directional antenna may be used to transmit/receive radio signals in any direction, a sector antenna may be used to transmit/receive radio signals from devices within a particular area, and a panel antenna may be a line of sight antenna used to transmit/receive radio signals in a relatively straight line. In some instances, the use of more than one antenna may be referred to as MIMO. In certain embodiments, antenna 1162 may be separate from network node 1160 and may be connectable to network node 1160 through an interface or port.

Antenna 1162, interface 1190, and/or processing circuitry 1 170 may be configured to perform any receiving operations and/or certain obtaining operations described herein as being performed by a network node. Any information, data and/or signals may be received from a wireless device, another network node and/or any other network equipment. Similarly, antenna 1162, interface 1190, and/or processing circuitry 1170 may be configured to perform any transmitting operations described herein as being performed by a network node. Any information, data and/or signals may be transmitted to a wireless device, another network node and/or any other network equipment.

Power circuitry 1187 may comprise, or be coupled to, power management circuitry and is configured to supply the components of network node 1160 with power for performing the functionality described herein. Power circuitry 1187 may receive power from power source 1 186. Power source 1186 and/or power circuitry 1 187 may be configured to provide power to the various components of network node 1160 in a form suitable forthe respective components (e.g., at a voltage and current level needed for each respective component). Power source 1 186 may either be included in, or external to, power circuitry 1187 and/or network node 1 160. For example, network node 1 160 may be connectable to an external power source (e.g., an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry 1 187. As a further example, power source 1 186 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry 1 187. The battery may provide backup power should the external power source fail. Other types of power sources, such as photovoltaic devices, may also be used.

Alternative embodiments of network node 1 160 may include additional components beyond those shown in Figure 13 that may be responsible for providing certain aspects of the network node’s functionality, including any of the functionality described herein and/or any functionality necessary to support the subject matter described herein. For example, network node 1 160 may include user interface equipment to allow input of information into network node 1 160 and to allow output of information from network node 1 160. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for network node 1 160.

As used herein, wireless device (WD) refers to a device capable, configured, arranged and/or operable to communicate wirelessly with network nodes and/or other wireless devices. Unless otherwise noted, the term WD may be used interchangeably herein with user equipment (UE). Communicating wirelessly may involve transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information through air. In some embodiments, a WD may be configured to transmit and/or receive information without direct human interaction. For instance, a WD may be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the network. Examples of a WD include, but are not limited to, a smart phone, a mobile phone, a cell phone, a voice over IP (VoIP) phone, a wireless local loop phone, a desktop computer, a personal digital assistant (PDA), a wireless cameras, a gaming console or device, a music storage device, a playback appliance, a wearable terminal device, a wireless endpoint, a mobile station, a tablet, a laptop, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a smart device, a wireless customer- premise equipment (CPE), a vehicle-mounted wireless terminal device, etc. A WD may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to- everything (V2X) and may in this case be referred to as a D2D communication device. As yet another specific example, in an Internet of Things (loT) scenario, a WD may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another WD and/or a network node. The WD may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the WD may be a UE implementing the 3GPP narrow band internet of things (NB-loT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances (e.g. refrigerators, televisions, etc.) personal wearables (e.g., watches, fitness trackers, etc.). In other scenarios, a WD may represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation. A WD as described above may represent the endpoint of a wireless connection, in which case the device may be referred to as a wireless terminal. Furthermore, a WD as described above may be mobile, in which case it may also be referred to as a mobile device or a mobile terminal.

As illustrated, wireless device 1110 includes antenna 1111, interface 1114, processing circuitry 1120, device readable medium 1130, user interface equipment 1132, auxiliary equipment 1134, power source 1136 and power circuitry 1137. WD 1110 may include multiple sets of one or more of the illustrated components for different wireless technologies supported by WD 1110, such as, for example, GSM, WCDMA, LTE, NR, WiFi, WiMAX, or Bluetooth wireless technologies, just to mention a few. These wireless technologies may be integrated into the same or different chips or set of chips as other components within WD 1110.

Antenna 1111 may include one or more antennas or antenna arrays, configured to send and/or receive wireless signals, and is connected to interface 1114. In certain alternative embodiments, antenna 1111 may be separate from WD 1110 and be connectable to WD 1110 through an interface or port. Antenna 1111, interface 1114, and/or processing circuitry 1120 may be configured to perform any receiving or transmitting operations described herein as being performed by a WD. Any information, data and/or signals may be received from a network node and/or another WD. In some embodiments, radio front end circuitry and/or antenna 1111 may be considered an interface.

As illustrated, interface 1114 comprises radio front end circuitry 1112 and antenna 1111. Radio front end circuitry 1112 comprise one or more filters 1118 and amplifiers 1116. Radio front end circuitry 1114 is connected to antenna 1111 and processing circuitry 1120, and is configured to condition signals communicated between antenna 1111 and processing circuitry 1120. Radio front end circuitry 1112 may be coupled to or a part of antenna 1111. In some embodiments, WD 1110 may not include separate radio front end circuitry 1112; rather, processing circuitry 1120 may comprise radio front end circuitry and may be connected to antenna 1111. Similarly, in some embodiments, some or all of RF transceiver circuitry 1122 may be considered a part of interface 1114. Radio front end circuitry 1112 may receive digital data that is to be sent out to other network nodes or WDs via a wireless connection. Radio front end circuitry 1112 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1118 and/or amplifiers 1116. The radio signal may then be transmitted via antenna 1111. Similarly, when receiving data, antenna 1111 may collect radio signals which are then converted into digital data by radio front end circuitry 1112. The digital data may be passed to processing circuitry 1120. In other embodiments, the interface may comprise different components and/or different combinations of components.

Processing circuitry 1120 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software, and/or encoded logic operable to provide, either alone or in conjunction with other WD 1110 components, such as device readable medium 1130, WD 1 110 functionality. Such functionality may include providing any of the various wireless features or benefits discussed herein. For example, processing circuitry 1120 may execute instructions stored in device readable medium 1130 or in memory within processing circuitry 1 120 to provide the functionality disclosed herein.

As illustrated, processing circuitry 1 120 includes one or more of RF transceiver circuitry 1122, baseband processing circuitry 1 124, and application processing circuitry 1 126. In other embodiments, the processing circuitry may comprise different components and/or different combinations of components. In certain embodiments processing circuitry 1 120 of WD 11 10 may comprise a SOC. In some embodiments, RF transceiver circuitry 1122, baseband processing circuitry 1 124, and application processing circuitry 1126 may be on separate chips or sets of chips. In alternative embodiments, part or all of baseband processing circuitry 1124 and application processing circuitry 1126 may be combined into one chip or set of chips, and RF transceiver circuitry 1122 may be on a separate chip or set of chips. In still alternative embodiments, part or all of RF transceiver circuitry 1122 and baseband processing circuitry 1124 may be on the same chip or set of chips, and application processing circuitry 1 126 may be on a separate chip or set of chips. In yet other alternative embodiments, part or all of RF transceiver circuitry 1122, baseband processing circuitry 1124, and application processing circuitry 1 126 may be combined in the same chip or set of chips. In some embodiments, RF transceiver circuitry 1122 may be a part of interface 1114. RF transceiver circuitry 1 122 may condition RF signals for processing circuitry 1 120.

In certain embodiments, some or all of the functionality described herein as being performed by a WD may be provided by processing circuitry 1120 executing instructions stored on device readable medium 1130, which in certain embodiments may be a computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by processing circuitry 1120 without executing instructions stored on a separate or discrete device readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a device readable storage medium or not, processing circuitry 1 120 can be configured to perform the described functionality. The benefits provided by such functionality are not limited to processing circuitry 1 120 alone or to other components of WD 1110, but are enjoyed by WD 1110 as a whole, and/or by end users and the wireless network generally.

Processing circuitry 1120 may be configured to perform any determining, calculating, or similar operations (e.g., certain obtaining operations) described herein as being performed by a WD. These operations, as performed by processing circuitry 1 120, may include processing information obtained by processing circuitry 1120 by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored by WD 11 10, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination.

Device readable medium 1130 may be operable to store a computer program, software, an application including one or more of logic, rules, code, tables, etc. and/or other instructions capable of being executed by processing circuitry 1120. Device readable medium 1130 may include computer memory (e.g., Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (e.g., a hard disk), removable storage media (e.g., a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device readable and/or computer executable memory devices that store information, data, and/or instructions that may be used by processing circuitry 1120. In some embodiments, processing circuitry 1120 and device readable medium 1130 may be considered to be integrated.

User interface equipment 1132 may provide components that allow for a human user to interact with WD 11 10. Such interaction may be of many forms, such as visual, audial, tactile, etc. User interface equipment 1132 may be operable to produce output to the user and to allow the user to provide input to WD 1110. The type of interaction may vary depending on the type of user interface equipment 1 132 installed in WD 1 110. For example, if WD 1 110 is a smart phone, the interaction may be via a touch screen; if WD 1 110 is a smart meter, the interaction may be through a screen that provides usage (e.g., the number of gallons used) or a speaker that provides an audible alert (e.g., if smoke is detected). User interface equipment 1 132 may include input interfaces, devices and circuits, and output interfaces, devices and circuits. User interface equipment 1 132 is configured to allow input of information into WD 11 10, and is connected to processing circuitry 1120 to allow processing circuitry 1120 to process the input information. User interface equipment 1132 may include, for example, a microphone, a proximity or other sensor, keys/buttons, a touch display, one or more cameras, a USB port, or other input circuitry. User interface equipment 1132 is also configured to allow output of information from WD 11 10, and to allow processing circuitry 1120 to output information from WD 11 10. User interface equipment 1132 may include, for example, a speaker, a display, vibrating circuitry, a USB port, a headphone interface, or other output circuitry. Using one or more input and output interfaces, devices, and circuits, of user interface equipment 1 132, WD 1 1 10 may communicate with end users and/or the wireless network, and allow them to benefit from the functionality described herein.

Auxiliary equipment 1 134 is operable to provide more specific functionality which may not be generally performed by WDs. This may comprise specialized sensors for doing measurements for various purposes, interfaces for additional types of communication such as wired communications etc. The inclusion and type of components of auxiliary equipment 1 134 may vary depending on the embodiment and/or scenario.

Power source 1 136 may, in some embodiments, be in the form of a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic devices or power cells, may also be used. WD 1 1 10 may further comprise power circuitry 1 137 for delivering power from power source 1 136 to the various parts of WD 1 1 10 which need power from power source 1 136 to carry out any functionality described or indicated herein. Power circuitry 1 137 may in certain embodiments comprise power management circuitry. Power circuitry 1 137 may additionally or alternatively be operable to receive power from an external power source; in which case WD 1 1 10 may be connectable to the external power source (such as an electricity outlet) via input circuitry or an interface such as an electrical power cable. Power circuitry 1 137 may also in certain embodiments be operable to deliver power from an external power source to power source 1 136. This may be, for example, for the charging of power source 1 136. Power circuitry 1 137 may perform any formatting, converting, or other modification to the power from power source 1 136 to make the power suitable for the respective components of WD 1 1 10 to which power is supplied.

Figure 14 illustrates one embodiment of a UE in accordance with various aspects described herein. As used herein, a user equipment or UE may not necessarily have a user in the sense of a human user who owns and/or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter). UE 12200 may be any UE identified by the 3rd Generation Partnership Project (3GPP), including a NB-loT UE, a machine type communication (MTC) UE, and/or an enhanced MTC (eMTC) UE. UE 1200, as illustrated in Figure 14, is one example of a WD configured for communication in accordance with one or more communication standards promulgated by the 3rd Generation Partnership Project (3GPP), such as 3GPP’s GSM, UMTS, LTE, and/or 5G standards. As mentioned previously, the term WD and UE may be used interchangeable. Accordingly, although Figure 14 is a UE, the components discussed herein are equally applicable to a WD, and vice-versa. In Figure 14, UE 1200 includes processing circuitry 1201 that is operatively coupled to input/output interface 1205, radio frequency (RF) interface 1209, network connection interface 121 1 , memory 1215 including random access memory (RAM) 1217, read-only memory (ROM) 1219, and storage medium 1221 orthe like, communication subsystem 1231 , power source 1233, and/or any other component, or any combination thereof. Storage medium 1221 includes operating system 1223, application program 1225, and data 1227. In other embodiments, storage medium 1221 may include other similar types of information. Certain UEs may utilize all of the components shown in Figure 14, or only a subset of the components. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

In Figure 14, processing circuitry 1201 may be configured to process computer instructions and data. Processing circuitry 1201 may be configured to implement any sequential state machine operative to execute machine instructions stored as machine-readable computer programs in the memory, such as one or more hardware-implemented state machines (e.g., in discrete logic, FPGA, ASIC, etc.); programmable logic together with appropriate firmware; one or more stored program, general-purpose processors, such as a microprocessor or Digital Signal Processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 1201 may include two central processing units (CPUs). Data may be information in a form suitable for use by a computer.

In the depicted embodiment, input/output interface 1205 may be configured to provide a communication interface to an input device, output device, or input and output device. UE 1200 may be configured to use an output device via input/output interface 1205. An output device may use the same type of interface port as an input device. For example, a USB port may be used to provide input to and output from UE 1200. The output device may be a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. UE 1200 may be configured to use an input device via input/output interface 1205 to allow a user to capture information into UE 1200. The input device may include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, another like sensor, or any combination thereof. For example, the input device may be an accelerometer, a magnetometer, a digital camera, a microphone, and an optical sensor. In Figure 14, RF interface 1209 may be configured to provide a communication interface to RF components such as a transmitter, a receiver, and an antenna. Network connection interface 1211 may be configured to provide a communication interface to network 1243a. Network 1243a may encompass wired and/or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, network 1243a may comprise a Wi-Fi network. Network connection interface 121 1 may be configured to include a receiver and a transmitter interface used to communicate with one or more other devices over a communication network according to one or more communication protocols, such as Ethernet, TCP/IP, SONET, ATM, or the like. Network connection interface 121 1 may implement receiver and transmitter functionality appropriate to the communication network links (e.g., optical, electrical, and the like). The transmitter and receiver functions may share circuit components, software or firmware, or alternatively may be implemented separately.

RAM 1217 may be configured to interface via bus 1202 to processing circuitry 1201 to provide storage or caching of data or computer instructions during the execution of software programs such as the operating system, application programs, and device drivers. ROM 1219 may be configured to provide computer instructions or data to processing circuitry 1201. For example, ROM 1219 may be configured to store invariant low-level system code or data for basic system functions such as basic input and output (I/O), startup, or reception of keystrokes from a keyboard that are stored in a non-volatile memory. Storage medium 1221 may be configured to include memory such as RAM, ROM, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, floppy disks, hard disks, removable cartridges, or flash drives. In one example, storage medium 1221 may be configured to include operating system 1223, application program 1225 such as a web browser application, a widget or gadget engine or another application, and data file 1227. Storage medium 1221 may store, for use by UE 1200, any of a variety of various operating systems or combinations of operating systems.

Storage medium 1221 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), floppy disk drive, flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard diskdrive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as a subscriber identity module or a removable user identity (SIM/RUIM) module, other memory, or any combination thereof. Storage medium 1221 may allow UE 1200 to access computer-executable instructions, application programs or the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied in storage medium 1221 , which may comprise a device readable medium.

In Figure 14, processing circuitry 1201 may be configured to communicate with network 1243b using communication subsystem 1231 . Network 1243a and network 1243b may be the same network or networks or different network or networks. Communication subsystem 1231 may be configured to include one or more transceivers used to communicate with network 1243b. For example, communication subsystem 1231 may be configured to include one or more transceivers used to communicate with one or more remote transceivers of another device capable of wireless communication such as another WD, UE, or base station of a radio access network (RAN) according to one or more communication protocols, such as IEEE 802.11 , CDMA, WCDMA, GSM, LTE, UTRAN, WiMax, orthe like. Each transceiver may include transmitter 1233 and/or receiver 1235 to implement transmitter or receiver functionality, respectively, appropriate to the RAN links (e.g., frequency allocations and the like). Further, transmitter 1233 and receiver 1235 of each transceiver may share circuit components, software or firmware, or alternatively may be implemented separately.

In the illustrated embodiment, the communication functions of communication subsystem 1231 may include data communication, voice communication, multimedia communication, short- range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. For example, communication subsystem 1231 may include cellular communication, Wi-Fi communication, Bluetooth communication, and GPS communication. Network 1243b may encompass wired and/or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, network 1243b may be a cellular network, a Wi-Fi network, and/or a nearfield network. Power source 1213 may be configured to provide alternating current (AC) or direct current (DC) power to components of UE 1200.

The features, benefits and/or functions described herein may be implemented in one of the components of UE 1200 or partitioned across multiple components of UE 1200. Further, the features, benefits, and/or functions described herein may be implemented in any combination of hardware, software or firmware. In one example, communication subsystem 1231 may be configured to include any of the components described herein. Further, processing circuitry 1201 may be configured to communicate with any of such components over bus 1202. In another example, any of such components may be represented by program instructions stored in memory that when executed by processing circuitry 1201 perform the corresponding functions described herein. In another example, the functionality of any of such components may be partitioned between processing circuitry 1201 and communication subsystem 1231. In another example, the non-computationally intensive functions of any of such components may be implemented in software or firmware and the computationally intensive functions may be implemented in hardware.

Figure 15 is a schematic block diagram illustrating a virtualization environment 1300 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to a node (e.g., a virtualized base station or a virtualized radio access node) or to a device (e.g., a UE, a wireless device or any other type of communication device) or components thereof and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components (e.g., via one or more applications, components, functions, virtual machines or containers executing on one or more physical processing nodes in one or more networks).

In some embodiments, some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines implemented in one or more virtual environments 1300 hosted by one or more of hardware nodes 1330. Further, in embodiments in which the virtual node is not a radio access node or does not require radio connectivity (e.g., a core network node), then the network node may be entirely virtualized.

The functions may be implemented by one or more applications 1320 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) operative to implement some of the features, functions, and/or benefits of some of the embodiments disclosed herein. Applications 1320 are run in virtualization environment 1300 which provides hardware 1330 comprising processing circuitry 1360 and memory 1390. Memory 1390 contains instructions 1395 executable by processing circuitry 1360 whereby application 1320 is operative to provide one or more of the features, benefits, and/or functions disclosed herein.

Virtualization environment 1300, comprises general-purpose or special-purpose network hardware devices 1330 comprising a set of one or more processors or processing circuitry 1360, which may be commercial off-the-shelf (COTS) processors, dedicated Application Specific Integrated Circuits (ASICs), or any other type of processing circuitry including digital or analog hardware components or special purpose processors. Each hardware device may comprise memory 1390-1 which may be non-persistent memory for temporarily storing instructions 1395 or software executed by processing circuitry 1360. Each hardware device may comprise one or more network interface controllers (NICs) 1370, also known as network interface cards, which include physical network interface 1380. Each hardware device may also include non-transitory, persistent, machine-readable storage media 1390-2 having stored therein software 1395 and/or instructions executable by processing circuitry 1360. Software 1395 may include any type of software including software for instantiating one or more virtualization layers 1350 (also referred to as hypervisors), software to execute virtual machines 1340 as well as software allowing it to execute functions, features and/or benefits described in relation with some embodiments described herein.

Virtual machines 1340, comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1350 or hypervisor. Different embodiments of the instance of virtual appliance 1320 may be implemented on one or more of virtual machines 1340, and the implementations may be made in different ways.

During operation, processing circuitry 1360 executes software 1395 to instantiate the hypervisor or virtualization layer 1350, which may sometimes be referred to as a virtual machine monitor (VMM). Virtualization layer 1350 may present a virtual operating platform that appears like networking hardware to virtual machine 1340.

As shown in Figure 15, hardware 1330 may be a standalone network node with generic or specific components. Hardware 1330 may comprise antenna 13225 and may implement some functions via virtualization. Alternatively, hardware 1330 may be part of a larger cluster of hardware (e.g. such as in a data center or customer premise equipment (CPE)) where many hardware nodes work together and are managed via management and orchestration (MANO) 13100, which, among others, oversees lifecycle management of applications 1320.

Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

In the context of NFV, virtual machine 1340 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of virtual machines 1340, and that part of hardware 1330 that executes that virtual machine, be it hardware dedicated to that virtual machine and/or hardware shared by that virtual machine with others of the virtual machines 1340, forms a separate virtual network elements (VNE).

Still in the context of NFV, Virtual Network Function (VNF) is responsible for handling specific network functions that run in one or more virtual machines 1340 on top of hardware networking infrastructure 1330 and corresponds to application 1320 in Figure 15.

In some embodiments, one or more radio units 13200 that each include one or more transmitters 13220 and one or more receivers 13210 may be coupled to one or more antennas 13225. Radio units 13200 may communicate directly with hardware nodes 1330 via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station.

In some embodiments, some signaling can be effected with the use of control system 13230 which may alternatively be used for communication between the hardware nodes 1330 and radio units 13200.

With reference to Figure 14, in accordance with an embodiment, a communication system includes telecommunication network 1410, such as a 3GPP-type cellular network, which comprises access network 1411 , such as a radio access network, and core network 1414. Access network 141 1 comprises a plurality of base stations 1412a, 1412b, 1412c, such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 1413a, 1413b, 1413c. Each base station 1412a, 1412b, 1412c is connectable to core network 1414 over a wired or wireless connection 1415. A first UE 1491 located in coverage area 1413c is configured to wirelessly connect to, or be paged by, the corresponding base station 1412c. A second UE 1492 in coverage area 1413a is wirelessly connectable to the corresponding base station 1412a. While a plurality of UEs 1491 , 1492 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 1412.

Telecommunication network 1410 is itself connected to host computer 1430, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. Host computer 1430 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. Connections 1421 and 1422 between telecommunication network 1410 and host computer 1430 may extend directly from core network 1414 to host computer 1430 or may go via an optional intermediate network 1420. Intermediate network 1420 may be one of, or a combination of more than one of, a public, private or hosted network; intermediate network 1420, if any, may be a backbone network or the Internet; in particular, intermediate network 1420 may comprise two or more sub-networks (not shown).

The communication system of Figure 16 as a whole enables connectivity between the connected UEs 1491 , 1492 and host computer 1430. The connectivity may be described as an over-the-top (OTT) connection 1450. Host computer 1430 and the connected UEs 1491 , 1492 are configured to communicate data and/or signaling via OTT connection 1450, using access network 141 1 , core network 1414, any intermediate network 1420 and possible further infrastructure (not shown) as intermediaries. OTT connection 1450 may be transparent in the sense that the participating communication devices through which OTT connection 1450 passes are unaware of routing of uplink and downlink communications. For example, base station 1412 may not or need not be informed about the past routing of an incoming downlink communication with data originating from host computer 1430 to be forwarded (e.g., handed over) to a connected UE 1491 . Similarly, base station 1412 need not be aware of the future routing of an outgoing uplink communication originating from the UE 1491 towards the host computer 1430.

Example implementations, in accordance with an embodiment, of the UE, base station and host computer discussed in the preceding paragraphs will now be described with reference to Figure 17. In communication system 1500, host computer 1510 comprises hardware 1515 including communication interface 1516 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of communication system 1500. Host computer 1510 further comprises processing circuitry 1518, which may have storage and/or processing capabilities. In particular, processing circuitry 1518 may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. Host computer 1510 further comprises software 151 1 , which is stored in or accessible by host computer 1510 and executable by processing circuitry 1518. Software 151 1 includes host application 1512. Host application 1512 may be operable to provide a service to a remote user, such as UE 1530 connecting via OTT connection 1550 terminating at UE 1530 and host computer 1510. In providing the service to the remote user, host application 1512 may provide user data which is transmitted using OTT connection 1550.

Communication system 1500 further includes base station 1520 provided in a telecommunication system and comprising hardware 1525 enabling it to communicate with host computer 1510 and with UE 1530. Hardware 1525 may include communication interface 1526 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of communication system 1500, as well as radio interface 1527 for setting up and maintaining at least wireless connection 1570 with UE 1530 located in a coverage area (not shown in Figure 17) served by base station 1520. Communication interface 1526 may be configured to facilitate connection 1560 to host computer 1510. Connection 1560 may be direct or it may pass through a core network (not shown in Figure 17) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, hardware 1525 of base station 1520 further includes processing circuitry 1528, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. Base station 1520 further has software 1521 stored internally or accessible via an external connection.

Communication system 1500 further includes UE 1530 already referred to. Its hardware 1535 may include radio interface 1537 configured to set up and maintain wireless connection 1570 with a base station serving a coverage area in which UE 1530 is currently located. Hardware 1535 of UE 1530 further includes processing circuitry 1538, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. UE 1530 further comprises software 1531 , which is stored in or accessible by UE 1530 and executable by processing circuitry 1538. Software 1531 includes client application 1532. Client application 1532 may be operable to provide a service to a human or non-human user via UE 1530, with the support of host computer 1510. In host computer 1510, an executing host application 1512 may communicate with the executing client application 1532 via OTT connection 1550 terminating at UE 1530 and host computer 1510. In providing the service to the user, client application 1532 may receive request data from host application 1512 and provide user data in response to the request data. OTT connection 1550 may transfer both the request data and the user data. Client application 1532 may interact with the user to generate the user data that it provides.

It is noted that host computer 1510, base station 1520 and UE 1530 illustrated in Figure 17 may be similar or identical to host computer 1430, one of base stations 1412a, 1412b, 1412c and one of UEs 1491 , 1492 of Figure 16, respectively. This is to say, the inner workings of these entities may be as shown in Figure 17 and independently, the surrounding network topology may be that of Figure 16.

In Figure 17, OTT connection 1550 has been drawn abstractly to illustrate the communication between host computer 1510 and UE 1530 via base station 1520, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure may determine the routing, which it may be configured to hide from UE 1530 or from the service provider operating host computer 1510, or both. While OTT connection 1550 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).

Wireless connection 1570 between UE 1530 and base station 1520 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to UE 1530 using OTT connection 1550, in which wireless connection 1570 forms the last segment. More precisely, the teachings of these embodiments may improve the handover process following fallback, and thereby provide benefits such as speeding up this process.

A measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring OTT connection 1550 between host computer 1510 and UE 1530, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring OTT connection 1550 may be implemented in software 151 1 and hardware 1515 of host computer 1510 or in software 1531 and hardware 1535 of UE 1530, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which OTT connection 1550 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 151 1 , 1531 may compute or estimate the monitored quantities. The reconfiguring of OTT connection 1550 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect base station 1520, and it may be unknown or imperceptible to base station 1520. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating host computer 1510’s measurements of throughput, propagation times, latency and the like. The measurements may be implemented in that software 151 1 and 1531 causes messages to be transmitted, in particular empty or‘dummy’ messages, using OTT connection 1550 while it monitors propagation times, errors etc.

Figure 18 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Figures 14 and 15. For simplicity of the present disclosure, only drawing references to Figure 18 will be included in this section. In step 1610, the host computer provides user data. In substep 161 1 (which may be optional) of step 1610, the host computer provides the user data by executing a host application. In step 1620, the host computer initiates a transmission carrying the user data to the UE. In step 1630 (which may be optional), the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1640 (which may also be optional), the UE executes a client application associated with the host application executed by the host computer.

Figure 19 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Figures 14 and 15. For simplicity of the present disclosure, only drawing references to Figure 19 will be included in this section. In step 1710 of the method, the host computer provides user data. In an optional substep (not shown) the host computer provides the user data by executing a host application. In step 1720, the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1730 (which may be optional), the UE receives the user data carried in the transmission.

Figure 20 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Figures 14 and 15. For simplicity of the present disclosure, only drawing references to Figure 20 will be included in this section. In step 1810 (which may be optional), the UE receives input data provided by the host computer. Additionally or alternatively, in step 1820, the UE provides user data. In substep 1821 (which may be optional) of step 1820, the UE provides the user data by executing a client application. In substep 181 1 (which may be optional) of step 1810, the UE executes a client application which provides the user data in reaction to the received input data provided by the host computer. In providing the user data, the executed client application may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the UE initiates, in substep 1830 (which may be optional), transmission of the user data to the host computer. In step 1840 of the method, the host computer receives the user data transmitted from the UE, in accordance with the teachings of the embodiments described throughout this disclosure.

Figure 21 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Figures 14 and 15. For simplicity of the present disclosure, only drawing references to Figure 21 will be included in this section. In step 1910 (which may be optional), in accordance with the teachings of the embodiments described throughout this disclosure, the base station receives user data from the UE. In step 1920 (which may be optional), the base station initiates transmission of the received user data to the host computer. In step 1930 (which may be optional), the host computer receives the user data carried in the transmission initiated by the base station.

Claims

1. A method (400) performed by a wireless device (100, 600) in a wireless communication network (10) for handover or redirection, the method comprising:

in response to determining (410) that a communication by the wireless device (100, 600) is to be commenced, moving (420) a first connection from a source radio access network (RAN) (350) to a target RAN (250, 350);

commencing (430) the communication over the target RAN (250, 350) using the first connection; and

in response to determining that the communication has been terminated, moving (440) the first connection or a second connection to the source RAN (350) from the target RAN (250, 350).

2. The method (400) of embodiment 1 , further comprising, in response to determining that a communication by the wireless device (100, 600) is to be commenced, moving a second connection from the target RAN (250, 350) to the source RAN (350).

3. The method (400) of embodiment 2, wherein the second connection comprises a PDN connection on an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) (250) and/or a PDU session on a Next Generation Radio Access Network (NG-RAN) (350).

4. The method (400) of any of embodiments 1 to 3, wherein the first connection comprises a PDU session on a NG-RAN (350) and/or a PDN connection on a E-UTRAN (250).

5. The method (400) of any of embodiments 1 to 4, wherein the communication comprises a voice call

6. The method (400) of any of embodiments 1 to 5, wherein the communication is unsupported by the source RAN (350), or is unsupported by a core network to which the source RAN (350) is connected.

7. The method (400) of any of embodiments 1 to 6, wherein the wireless device (100, 600) is connected simultaneously to the source RAN (350) and the target RAN (250, 350).

8. The method (400) of any of embodiments 1 to 7, further comprising, in response to determining that the communication has been terminated, moving the first connection to the source RAN (350) from the target RAN (250, 350).

9. The method (400) of embodiment 8, comprising moving the first connection to the source RAN (350) from the target RAN (250) after a predetermined time period following commencement of the communication or moving the first connection to the target RAN (250).

10. The method of any one of claims 1 - 9 wherein the source RAN comprises a NG-RAN and the target RAN comprises an E-U-TRAN.

11. The method of any one of claims 1 - 9 wherein the source RAN comprises a first NG- RAN and the target RAN comprises a second NG-RAN.

12. The method (400) of any of the previous embodiments, further comprising:

providing user data; and

forwarding the user data to a host computer via transmission to a base station.

13. A method (500) performed by a network node (150, 700) in a wireless communication network (10) for handover or redirection of a wireless device (100, 600), the method (500) comprising:

determining (510) that a wireless device (100, 600) connected to a second RAN (250, 350) was previously connected to a first RAN (350); and

in response to a determination that the wireless device (100, 600) has completed a communication through the second RAN (250, 350), causing (520) the wireless device (100, 600) to handover or be redirected to the first RAN (350).

14. The method (500) of claim 13, wherein determining that a wireless device (100, 600) connected to a second RAN (250, 350) was previously connected to a first RAN (350) comprises determining that the wireless device (100, 600) is connected to the E-UTRAN (250) following a fallback or redirect procedure from the NG-RAN (350).

15. The method (500) of claim 14, wherein the fallback or redirect procedure comprises a RAT fallback procedure or an EPS fallback procedure.

16. The method (500) of claim 15, wherein determining that a wireless device (100, 600) connected to a second RAN (250, 350) was previously connected to a first RAN (350) comprises receiving information that the wireless device (100, 600) was previously connected to the first RAN (350).

17. The method (500) of claim 16, wherein the information is received from the first RAN (350), a gNB (360) or eNB (260) in the first RAN (350), an AMF in the first RAN (350), a MME in an EPC, a node in the first RAN (350) or a node in the second RAN (250, 350).

18. The method (500) of claim 16 or 17, wherein the information comprises a fallback indicator or redirection indicator.

19. The method (500) of claim 18, wherein the fallback indicator or redirection indicator is received in a Relocation Request message or a handover request message.

20. The method (500) of any of claims 13 to 19, wherein determining that a wireless device (100, 600) connected to a second RAN (250, 350) was previously connected to a first RAN (350) comprises determining an identifier of a network or a network node (150, 700) in the first RAN (350) to which the wireless device (100, 600) was previously connected.

21. The method (500) of claim 20, wherein causing the wireless device (100, 600) to handover or be redirected to the first RAN (350) comprises causing the handover or redirection based on the identifier.

22. The method (500) of claim 21 , comprising selecting a handover or redirect target cell based on the indicator or selecting a dedicated handover or redirect target frequency list based on the identifier.

23. The method (500) of any of claims 20 to 22, wherein the identifier comprises a PLMN ID.

24. The method (500) of any of claims 20 to 23, wherein causing the wireless device (100, 600) to handover or be redirected to the first RAN (350) comprises causing handover or redirection to the network or the network node (150, 700) in the first RAN (350) to which the wireless device (100, 600) was previously connected.

25. The method (500) of any of claims 20 to 24, wherein the identifier is received in a Relocation Request message or a handover request message.

26. The method (500) of any of claims 13 to 25, comprising determining that the wireless device (100, 600) has completed the communication through the second RAN (250, 350).

27. The method (500) of claim 26, wherein the second RAN comprises a E-UTRAN (250) and wherein determining that the wireless device (100, 600) has completed the communication through the E-UTRAN (250) comprises determining the absence of a radio access bearer or bearer with QCI=1 .

28. The method (500) of any of claims 1 1 to 25, wherein causing the wireless device (100, 600) to handover or be redirected to the first RAN (350) comprises causing handover or redirection to the same network or node in the first RAN (350) to which the wireless device (100, 600) was previously connected.

29. The method (500) of any of claims 1 1 to 26, wherein causing the wireless device (100, 600) to handover or be redirected to the first RAN (350) causing handover to a PLMN to which the wireless device (100, 600) was previously connected.

30. The method (500) of any of claims 1 1 to 27, wherein the communication through the second RAN (250, 350) comprises a voice call.

31 . The method (500) of any of claims 1 1 to 28, wherein the network node (150, 700) comprises a base station.

32. The method (500) of any of claims 1 1 to 28, wherein the network node (150, 700) comprises a node in the E-UTRAN (250).

33. The method (500) of claim 30, wherein the network node (150, 700) comprises an eNB (260) or ng-eNB (370).

34. The method (500) of any of claims 1 1 to 28, wherein the network node (150, 700) comprises a node in the NG-RAN (350).

35. The method (500) of claim 32, wherein the network node (150, 700) comprises a gNB (360), eNB (260) or AMF (320).

36. The method (500) of any of claims 1 1 to 28, wherein the network node (150, 700) comprises a MME (225).

37. The method (500) of any of claims 13 to 36, wherein determining that a wireless device (100, 600) connected to a second RAN 250, 350) was previously connected to a first RAN (350) comprises determining that the wireless device (100, 600) was handed over to the second RAN (250, 350) to begin the communication.

38. The method (500) of claim 37, wherein determining that the wireless device (100, 600) was handed over or redirected to the second RAN 250, 350) to begin the communication comprises receiving an indication from the first RAN (350).

39. The method (500) of any of claims 13 to 38, wherein causing the wireless device (100, 600) to handover or be redirected to the first RAN (350) comprises indicating to a node in the second RAN (250, 350) that the wireless device (100, 600) was connected to a node in the first RAN (350).

40. The method (500) of claim 39, wherein the node in the second RAN (250, 350) is a eNB (260) or ng-eNB (370).

41. The method (500) of any of claims 13 to 40, wherein the communication is of a type that is unsupported by the first RAN (350).

42. The method (500) of any of any one of claim 13 - 41 , further comprising:

obtaining user data; and

forwarding the user data to a host computer or a wireless device (100, 600).

43. A wireless device (100, 600) in a wireless communication network (10) configured to: in response to determining (410) that a communication by the wireless device (100, 600) is to be commenced, move (420) a first connection from a source RAN (350) to a target RAN (250, 350);

commence (430) the communication over the target RAN (250, 350) using the first connection; and

in response to determining that the communication has been terminated, move (440) the first connection or a second connection to the source RAN (350) from the target RAN (250, 350).

44. The wireless device (100, 600) of claim 43 further configured to perform any one of the methods of claims 2 - 12.

45. A computer program (695) comprising executable instructions that, when executed by a processing circuit in a wireless device (100) in a wireless communication network, causes the wireless device (100) to perform any one of the methods of claims 1 - 12.

46. A carrier containing a computer program (695) of claim 45, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

47. A non-transitory computer-readable storage medium (690) containing a computer program (695) comprising executable instructions that, when executed by a processing circuit (640) in a wireless device (100) in a wireless communication network causes the wireless device (100) to perform any one of the methods of claims 1 - 12.

48. A network node (150, 700) in a wireless communication network (10) configured to: determine (510) that a wireless device (100, 600) connected to a second RAN (250, 350) was previously connected to a first RAN (350); and

in response to a determination that the wireless device (100, 600) has completed a communication through the second RAN (250, 350), cause (520) the wireless device (100, 600) to handover or be redirected to the first RAN (350).

49. The network node (150, 700) of claim 48 further configured to perform any one of the methods of claims 13 - 42.

50. A computer program (695) comprising executable instructions that, when executed by a processing circuit (730) in a network node (700) in a wireless communication network, causes the network node (700) to perform any one of the methods of claims 13 - 42.

51 . A carrier containing a computer program (795) of claim 48, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

52. A non-transitory computer-readable storage medium (790) containing a computer program (795) comprising executable instructions that, when executed by a processing circuit (730) in a network node (700)in a wireless communication network causes the network node (700) to perform any one of the methods of claims 13 - 42.