WO2023105073A1

WO2023105073A1 - Inter-network-node admission control for a sidelink relay ue

Info

Publication number: WO2023105073A1
Application number: PCT/EP2022/085253
Authority: WO
Inventors: Antonino ORSINO; Liwei QIU
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2021-12-10
Filing date: 2022-12-09
Publication date: 2023-06-15
Anticipated expiration: 2024-06-10

Abstract

Systems and methods are disclosed for enabling inter-network node admission control for a sidelink relay User Equipment (UE). In one embodiment, a method performed by a candidate target relay UE comprises receiving, from a target network node for a handover of a remote UE in association with a path switch procedure in which the candidate target relay UE is a candidate target relay UE for the path switch procedure, a message that enquires as to whether the candidate target relay UE acknowledges to act as a relay UE. The method further comprises sending, to the target network node, a response that comprises information that indicates whether the candidate target relay UE acknowledges to act as a relay UE. In this manner, during direct to indirect path switch for inter-network-node scenario, the target network node and ultimately the source network node can know whether the selected target relay UE is suitable.

Description

INTER-NETWORK-NODE ADMISSION CONTROL FOR A SIDELINK RELA 1 UE

Related Applications

This application claims the benefit of provisional patent application serial number 63/288,275, filed December 10, 2021, the disclosure of which is hereby incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates to a cellular communications system and, more specifically, to User Equipment (UE) to Network (U2N) relay via a sidelink in a cellular communications system.

Background

/ Sidelink Transmissions in New Radio (NR)

From Releases 12 to Release 15, Sidelink transmissions are designed based on the air interface of Long Term Evolution (LTE) Advanced (LTE-A). In Release 16, New Radio (NR) Sidelink transmissions are specified by inheriting some parts of concepts from LTE-A. A new introduction to the physical layer structure of NR is provided. Furthermore, enhancements to public safety, relay, etc. are planned in the Third Generation Partnership Project (3 GPP).

2 Layer 2 (L2) UE-to-Network Relay

In 3GPP Technical Report (TR) 23.752 V17.0.0 clause 6.7, the layer-2 based User Equipment (UE)-to-Network relay is described.

2.1 General Information

In clause 6.7 of 3GPP TR 23.752, the protocol architecture supporting a Layer 2 (L2) UE- to-Network Relay UE is provided. The L2 UE-to-Network Relay UE provides forwarding functionality that can relay any type of traffic over the sidelink, which is referred to as the PC5 link (i.e., the direct link between two UEs).

The L2 UE-to-Network Relay UE provides the functionality to support connectivity to the Fifth Generation System (5GS) for Remote User Equipments (UEs). A UE is considered to be a Remote UE if it has successfully established a PC5 link to the L2 UE-to-Network Relay UE. A Remote UE can be located within Next Generation Radio Access Network (NG-RAN) coverage or outside of NG-RAN coverage. Figure 1 illustrates the protocol stack for the user plane transport, related to a Protocol Data Unit (PDU) Session, including a Layer 2 UE-to-Network Relay UE. The PDU layer corresponds to the PDU carried between the Remote UE and the Data Network (DN) over the PDU session. It is important to note that the two endpoints of the Packet Data Convergence Protocol (PDCP) link are the Remote UE and the NR base station (gNB). The relay function is performed below PDCP. This means that data security is ensured between the Remote UE and the gNB without exposing raw data at the UE-to-Network Relay UE.

The adaptation relay layer within the UE-to-Network Relay UE can differentiate between Signaling Radio Bearers (SRBs) and Data Radio Bearers (DRBs) for a particular Remote UE. The adaption relay layer is also responsible for mapping PC5 traffic to one or more DRBs of the Uu (i.e., the interface between the NG-RAN and the L2 UE-to-Network Relay UE). The definition of the adaptation relay layer is under the responsibility of Radio Access Network (RAN) Working Group 2 (WG2) in 3GPP.

Figure 2 illustrates the protocol stack of the Non-Access Stratum (NAS) connection for the Remote UE to the NAS Mobility Management (NAS-MM) and NAS Session Management (NAS-SM) components. The NAS messages are transparently transferred between the Remote UE and 5G-Access Network (AN) (i.e., the NG-RAN) over the Layer 2 UE-to-Network Relay UE using:

• PDCP end-to-end connection where the role of the UE-to-Network Relay UE is to relay the PDUs over the SRB without any modifications.

• N2 connection between the 5G-AN (i.e., the NG-RAN) and Access and Mobility Management Function (AMF) over N2.

• N3 connection AMF and Session Management Function (SMF) over Ni l.

The role of the UE-to-Network Relay UE is to relay the PDUs from the SRB without any modifications.

3 Service Continuity

3.1 General

L2 UE-to-Network Relay uses the RAN2 principle of the Rel-15 NR handover procedure as the baseline Access Stratum (AS) layer solution to guarantee service continuity, i.e., gNB hands over the Remote UE to a target cell or target Relay UE, including:

1) Handover preparation type of procedure between gNB and Relay UE (if needed);

2) Radio Resource Control (RRC) Reconfiguration to Remote UE, Remote UE switching to the target, and; 3) Handover complete message, similar to the legacy procedure.

Exact content of the messages (e.g., handover command) will be discussed in the Work Item (WI) phase. This does not imply that inter-node message(s) will be sent over Uu.

Below, the common parts of intra-gNB cases and inter-gNB cases are described. For the inter-gNB cases, compared to the intra-gNB cases, potential different parts on RAN2 Uu interface will be discussed in detail in the WI phase.

3.2 Switching from Indirect to Direct Path

For service continuity of L2 UE-to-Network (U2N) relay, the following baseline procedure illustrated in Figure 3 is used, in case of Remote UE switching to direct Uu cell.

Figure 3 illustrates a procedure for Remote UE switching to direct Uu cell. The process of Figure 3 includes the following steps:

1. The Uu measurement configuration and measurement report signaling procedures is performed to evaluate both relay link measurement and Uu link measurement. The measurement results from U2N Remote UE are reported when configured reporting criteria is met. The Sidelink (SL) relay measurement report includes at least U2N Relay UE Identity (ID), serving cell ID, and SL Reference Signal Received Power (SL-RSRP) information.

2. The gNB decides to switch the Remote UE onto direct Uu path.

3. The gNB sends RRCReconfiguration message to the U2N Remote UE. The U2N Remote UE stops user plane (UP) and control plane (CP) transmission via U2N Relay UE after reception of RRCReconfiguration message from the gNB.

4. The U2N Remote UE synchronizes with the gNB and performs Random Access.

5. The UE (i.e., previous U2N Remote UE) sends the RRCReconfigurationComplete to the gNB via target path, using the configuration provided in the RRCReconfiguration message. From this step, the U2N Remote UE moves the RRC connection to the gNB

6. The gNB sends RRCReconfiguration message to the U2N Relay UE to reconfigure the connection between the U2N Relay UE and the gNB. The RRCReconfiguration message to the U2N Relay UE can be sent any time after step 3 based on gNB implementation (e g., to release Uu and PC5 Radio Link Control (RLC) configuration for relaying, and bearer mapping configuration between PC5 RLC and Uu RLC).

7. Either U2N Relay UE or U2N Remote UE can initiate the PC5 unicast link release (PC5-S). The timing to execute link release is up to UE implementation. The U2N Relay UE can execute PC5 connection reconfiguration to release PC5 RLC for relaying upon reception of RRC Reconfiguration by gNB in Step 6, or the UE (i.e., previous U2N Remote UE) can execute PC5 connection reconfiguration to release PC5 RLC for relaying upon reception of RRC Reconfiguration by gNB in Step 3.

8. The data path is switched from indirect path to direct path between the UE (i.e., previous U2N Remote UE) and the gNB. Step 8 can be executed in parallel or after step 5, which is independent of step 6 and step 7. The DL/UL lossless delivery during the path switch is done according to PDCP data recovery procedure.

3.3 Switching from Direct to Indirect Path

For service continuity of L2 UE-to-Network Relay, the following baseline procedure illustrated in Figure 4 is used, in case of Remote UE switching to indirect Relay UE:

Figure 4 illustrates a procedure for Remote UE switching to indirect Relay UE. The process of Figure 4 includes the following steps:

1. The U2N Remote UE reports one or multiple candidate U2N Relay UE(s) and legacy Uu measurements, after it measures/discovers the candidate U2N Relay UE(s).

The UE may filter the appropriate U2N Relay UE(s) according to Relay selection criteria before reporting. The UE shall report only the U2N Relay UE candidate(s) that fulfil the higher layer criteria.

The reporting can include at least U2N Relay UE ID, U2N Relay UE’ s serving cell ID, and SD-RSRP information.

2. The gNB decides to switch the U2N Remote UE to a target U2N Relay UE. Then the gNB sends an RRCReconfiguration message to the target U2N Relay UE, which can include at least Uu and PC5 RLC configuration for relaying, and bearer mapping configuration.

Note: At step 2, the gNB may decide to perform a normal handover rather than a path switch to an indirect path.

3. The gNB sends the RRCReconfiguration message to the U2N Remote UE. The contents in the RRCReconfiguration message can include at least U2N Relay UE ID, PC5 RLC configuration for relay traffic and the associated end-to-end radio bearer(s). The U2N Remote UE stops User Plane (UP) and Control Plane (CP) transmission over Uu after reception of RRCReconfiguration message from the gNB.

4. The U2N Remote UE establishes PC5 connection with target U2N Relay UE

5. The U2N Remote UE completes the path switch procedure by sending the RRCReconfigurationComplete message to the gNB via the Relay UE. 6. The data path is switched from direct path to indirect path between the U2N Remote UE and the gNB.

Note: FFS in case the target relay UE is in IDLE/INACTIVE, if supported.

Summary

Systems and methods are disclosed for enabling inter-network node admission control for a sidelink relay User Equipment (UE). In one embodiment, a method performed by a candidate target relay UE comprises receiving, from a target network node for a handover of a remote UE in association with a path switch procedure in which the candidate target relay UE is a candidate target relay UE for the path switch procedure, a message that enquires as to whether the candidate target relay UE acknowledges to act as a relay UE. The method further comprises sending, to the target network node, a response that comprises information that indicates whether the candidate target relay UE acknowledges to act as a relay UE. In this manner, during direct to indirect path switch for inter-network-node scenario, the target network node and ultimately the source network node can know whether the selected target relay UE is a suitable target relay UE when triggering the sidelink relay path switch. This will avoid unnecessary signaling overhead for potential failure of admission control.

In one embodiment, a serving cell of the candidate target relay UE is controlled by a source network node for the handover and is different than a serving cell of the target relay UE which is controlled by the target network node.

In one embodiment, the steps of receiving and sending are performed prior to triggering of the handover of the remote UE from the source network node to the target network node.

In one embodiment, the steps of receiving and sending are performed after triggering of the handover of the remote UE from the source network node to the target network node but before the target network node sends a handover request acknowledgement to the source network node.

Corresponding embodiment of a target relay UE are also disclosed. In one embodiment, a target relay UE is adapted to receive, from a target network node for a handover of a remote UE in association with a path switch procedure in which the candidate target relay UE is a candidate target relay UE for the path switch procedure, a message that enquires as to whether the candidate target relay UE acknowledges to act as a relay UE. The target relay UE is further adapted to send, to the target network node, a response that comprises information that indicates whether the candidate target relay UE acknowledges to act as a relay UE. In one embodiment, a target relay UE comprises a communication interface comprising a transmitter and a receiver, and processing circuitry associated with the communication interface. The processing circuitry is configured to cause the candidate target relay UE to receive, from a target network node for a handover of a remote UE in association with a path switch procedure in which the candidate target relay UE is a candidate target relay UE for the path switch procedure, a message that enquires as to whether the candidate target relay UE acknowledges to act as a relay UE. The processing circuitry is further configured to cause the candidate target relay UE to send, to the target network node, a response that comprises information that indicates whether the candidate target relay UE acknowledges to act as a relay UE.

Embodiments of a method performed by a source network node are also disclosed. In one embodiment, a method performed by a source network node comprises selecting one or more candidate target relay UEs for a path switch procedure for a remote UE, the one or more candidate target relay UEs each having a serving cell that is: (a) different than a serving cell of the remote UE and (b) controlled by a target network node, the target network node being a network node other than the source network node. The method further comprises sending, to the target network node, a message comprising information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE and receiving, from the target network node, a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

In one embodiment, the method further comprises receiving, from the remote UE, a report comprising a list of candidate relay UEs, wherein selecting the one or more candidate target relay UEs for the path switch procedure for the remote UE comprises selecting the one or more candidate target relay UEs for the path switch procedure for the remote UE from the list of candidate relay UEs. In one embodiment, the report received from the remote UE further comprises for each candidate relay UE in the list, information that indicates a serving cell of the candidate relay UE.

In one embodiment, the response received from the target network node comprises information that indicates that at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE, and the method further comprises, responsive to the response comprising the information that indicates that the at least one of the one or more candidate target relay UEs acknowledge to act as a relay UE, performing one or more actions to complete handover of the remote UE to the target network node and a path switch for the remote UE such that the remote UE communicates with the target network node via a relay UE, the relay UE being one of the at least one of the one or more candidate target relay UEs that acknowledge to act as a relay UE.

In one embodiment, sending, to the target network node, the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE comprises sending the message to the target network node prior to triggering a handover procedure for handover of the remote UE from the source network node to the target network node. In one embodiment, receiving, from the target network node, the response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE comprises receiving the response from the target network node prior to triggering a handover procedure for handover of the remote UE from the source network node to the target network node. In one embodiment, the response received from the target network node comprises information that indicates that at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE, and the method further comprises, responsive to the response comprising the information that indicates that the at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE, sending a handover request to the target network node to initiate a handover procedure for handover of the remote UE from the source network node to the target network node.

In one embodiment, sending, to the target network node, the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE comprises sending the message to the target network node at the time of or after triggering a handover procedure for handover of the remote UE from the source network node to the target network node but before the target network node responds with a handover acknowledgment. In one embodiment, the message sent to the target network node is a handover request. In one embodiment, receiving, from the target network node, the response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE comprises receiving a handover request acknowledgment from the target network node, the handover request acknowledgment comprising the information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE. In one embodiment, the response received from the target network node comprises information that indicates that at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE, and the method further comprises, responsive to the response comprising the information that indicates that the at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE, performing one or more actions for a path switch procedure for the remote UE such that the remote UE communicates with the target network node via a relay UE, the relay UE being one of the at least one of the one or more candidate target relay UEs that acknowledges to act as a relay UE.

Corresponding embodiments of a source network node are also disclosed. In one embodiment, a source network node is adapted to select one or more candidate target relay UEs for a path switch procedure for a remote UE, the one or more candidate target relay UEs each having a serving cell that is: (a) different than a serving cell of the remote UE and (b) controlled by a target network node, the target network node being a network node other than the source network node. The source network node is further adapted to send, to the target network node, a message comprising information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE and receive, from the target network node, a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

In one embodiment, a source network node comprises a communication interface and processing circuitry associated with the communication interface. The processing circuitry is configured to cause the source network node to select one or more candidate target relay UEs for a path switch procedure for a remote UE, the one or more candidate target relay UEs each having a serving cell that is: (a) different than a serving cell of the remote UE and (b) controlled by a target network node, the target network node being a network node other than the source network node. The processing circuitry is further configured to cause the source network node to send, to the target network node, a message comprising information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE and receive, from the target network node, a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

Embodiments of a method performed by a target network node are also disclosed. In one embodiment, a method performed by a target network node comprises receiving, from a source network node, a message comprising information that indicates one or more candidate target relay UEs for a path switch procedure for a remote UE), the one or more candidate target relay UEs each having a serving cell that is controlled by the target network node. The method further comprises, for each candidate target relay UE from the one or more candidate target relay UEs indicated in the message received from the source network node, sending, to the candidate target relay UE, a message that enquires as to whether the candidate target relay UE acknowledges to act as a relay UE and receiving, from the candidate target relay UE, a response that comprises information that indicates whether the candidate target relay UE acknowledges to act as a relay UE. The method further comprises sending, to the source network node, a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE, based on the response(s) received from the one or more candidate target relay UEs.

In one embodiment, receiving, from the source network node, the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE comprises receiving the message from the source network node prior to receiving a message that triggers a handover procedure for handover of the remote UE from the source network node to the target network node. In one embodiment, sending, to the source network node, the response comprising information that indicates whether the one or more candidate target relay UEs acknowledge to act as a relay UE comprises sending the response to the source network node prior to receiving a message that triggers a handover procedure for handover of the remote UE from the source network node to the target network node. In one embodiment, the response sent to the source network node comprises information that indicates that at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE, and the method further comprises receiving a handover request from the source network node to initiate a handover procedure for handover of the remote UE from the source network node (504) to the target network node.

In one embodiment, receiving, from the source network node, the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE comprises receiving the message from the source network node at the time of or after triggering of a handover procedure for handover of the remote UE from the source network node to the target network node but before the target network node responds to the source network node with a handover acknowledgment. In one embodiment, the message received from the source network node is a handover request. In one embodiment, sending, to the source network node, the response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE comprises sending a handover request acknowledgment to the source network node, the handover request acknowledgment comprising the information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

Corresponding embodiments of a target network node are also disclosed. In one embodiment, a target network node is adapted to receive, from a source network node, a message comprising information that indicates one or more candidate target relay UEs for a path switch procedure for a remote UE, the one or more candidate target relay UEs each having a serving cell that is controlled by the target network node. The target network node is further adapted to, for each candidate target relay UE from the one or more candidate target relay UEs indicated in the message received from the source network node, send, to the candidate target relay UE, a message that enquires as to whether the candidate target relay UE acknowledges to act as a relay UE and receive, from the candidate target relay UE, a response that comprises information that indicates whether the candidate target relay UE acknowledges to act as a relay UE. The target network node is further adapted to send, to the source network node, a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE, based on the response(s) received from the one or more candidate target relay UEs.

In one embodiment, a target network node comprises a communication interface and processing circuitry associated with the communication interface. The processing circuitry is configured to cause the target network node to receive, from a source network node, a message comprising information that indicates one or more candidate target relay UEs for a path switch procedure for a remote UE, the one or more candidate target relay UEs each having a serving cell that is controlled by the target network node. The processing circuitry is further configured to cause the target network node to, for each candidate target relay UE from the one or more candidate target relay UEs indicated in the message received from the source network node, send, to the candidate target relay UE, a message that enquires as to whether the candidate target relay UE acknowledges to act as a relay UE and receive, from the candidate target relay UE, a response that comprises information that indicates whether the candidate target relay UE acknowledges to act as a relay UE. The processing circuitry is further configured to cause the target network node to send, to the source network node, a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE, based on the response(s) received from the one or more candidate target relay UEs.

Brief Description of the Drawings

The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

Figure 1 illustrates the protocol stack for the user plane transport, related to a Protocol Data Unit (PDU) Session, including a Layer 2 User Equipment (UE)-to-Network Relay UE;

Figure 2 illustrates the protocol stack of the Non-Access Stratum (NAS) connection for the Remote UE to the NAS Mobility Management (NAS-MM) and NAS Session Management (NAS-SM) components; Figure 3 illustrates a baseline procedure for Remote UE switching to a direct Uu cell;

Figure 4 illustrates a baseline procedure for Remote UE switching to indirectly Relay UE;

Figure 5 illustrates one example of an inter-base station path switch procedure for a sidelink relay UE in accordance with a first embodiment of the present disclosure;

Figure 6 illustrates one example of an inter-base station path switch procedure for a sidelink relay UE in accordance with a second embodiment of the present disclosure;

Figure 7 shows an example of a communication system in accordance with some embodiments;

Figure 8 shows a UE in accordance with some embodiments;

Figure 9 shows a network node in accordance with some embodiments;

Figure 10 is a block diagram of a host, which may be an embodiment of the host of Figure 7, in accordance with various aspects described herein;

Figure 11 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments may be virtualized; and

Figure 12 shows a communication diagram of a host communicating via a network node with a UE over a partially wireless connection in accordance with some embodiments.

Detailed Description

The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

There currently exist certain challenge(s). During the path switch between remote User Equipment(s) (UE(s)) and relay UE(s) belonging to different Next Generation Radio Access Network (NG-RAN) nodes, one potential issue is that the target NG-RAN node (e.g., target New Radio base station (gNB)) may not be able to execute admission control properly without knowing the willingness of the candidate relay UE(s) to act as a relay UE. Also, since the relay UE is a mobile UE, from the time when it has been discovered by a remote UE to the time when the relay UE is selected by the source NG-RAN node (e.g., source gNB) for the path switch, the relay UE may no longer be in a favorable channel condition to be a relay UE. In this case, if no admission control is done by the target NG-RAN node before sending a positive acknowledgement (for the handover) to the source NG-RAN node, there is a possibility that the candidate relay UE may reject the request thereby causing a failure of the path switch procedure.

Also, in Third Generation Partnership Project (3 GPP) Release (Rel-) 17, the inter-gNB scenario was not supported and thus there currently is no signaling between gNBs in case a path switch is performed at a remote UE to a relay UE that is camping in a different serving cell.

Certain aspects of the disclosure and their embodiments may provide solutions to the aforementioned or other challenges. With embodiments of the systems and methods disclosed herein, the mobility of a target relay UE (e.g., the target relay UE for a Remote UE switching to indirect Relay UE procedure) is taken into account during the path switch procedure for a remote UE that is camping in a serving cell that is different from a serving cell of the target relay UE. In one embodiment, one or more of the following actions are performed:

1. The remote UE sends to a source network node (e.g., a source NG-RAN node such as, e.g., a source gNB) a measurement report including a list of candidate cells and candidate relay UEs. For each candidate relay UE, the remote UE includes a serving cell Identity (ID) so that the correct target network node (e.g., a target NG-RAN node such as, e.g., a target gNB) for the relay UE can be identified.

2. The source network node selects, from the candidate relay UEs, a target relay UE that is camping on a serving cell that is different from a serving cell for the remote UE.

3. The source network node sends a handover request to the target network node. The target network node is the network node controlling the serving cell of the target relay UE.

4. Before sending an acknowledgement for the handover, the target network node sends a signaling to the target relay UE for informing the target relay UE that it has been selected as the target relay UE and asking whether the target relay UE accepts or rejects the handover (i.e., accepts or rejects the path switch).

5. After the target relay UE responds to the target network node (with a positive or negative acknowledgment), the target network node can either send to the source network node a handover acknowledgment (to indicate that the handover can be done) or a handover rejection (eventually with a failure cause explaining why the handover has failed).

6. If the source network node receives a positive acknowledgement from the target relay

UE, the source network node continues performing the path switch procedure. However, if the source network node receives a negative acknowledgement from the target relay UE, the source network node can either abort the path switch procedure and send the remote UE to Radio Resource Control (RRC) Idle mode (RRC IDLE) / RRC Inactive mode (RRC IN ACTIVE) or select another target relay UE (and repeat steps 1 to 6) or select a candidate cell instead of a target relay UE (this basically means legacy handover procedure).

Certain embodiments may provide one or more of the following technical advantage(s). During direct to indirect path switch for inter-network-node (e.g., inter-NG-RAN-node or inter- gNB) scenario, the source network node can know whether the selected target relay UE is still a suitable target relay UE for when triggering the sidelink relay path switch. This will avoid unnecessary signaling overhead in the PC5 or Uu, and Xn interfaces for potential failure of admission control. Further, long connection interruption is avoided, and power consumption of the relay UE is also decreased.

Embodiments of the systems and methods disclosed herein refer to the 3GPP New Radio (NR) Radio Access Technology (RAT) but can be applied also to the Long Term Evolution (LTE) RAT and any other RAT enabling direct communication between two (or more) nearby devices without any loss of meaning.

Further, as used herein, a remote UE, or RM UE, is a UE that is able to transmit/receive packets from/to a NR base station (gNB) via an intermediate UE, which is referred to herein as a relay UE or RL UE. Note that a relay UE is preferably a mobile device.

The link or radio link over which the signals are transmitted between at least two UEs for Device-to-Device (D2D) operation is referred to herein as the sidelink (SL). The signals transmitted between the UEs for D2D operation are referred to herein as SL signals. The term sidelink or SL may also interchangeably be referred to as a D2D link, a Vehicle to Anything (V2X) link, prose link, peer-to-peer link, PC5 link, etc. The SL signals may also interchangeably be referred to as V2X signals, D2D signals, prose signals, PC5 signals, peer-to-peer signals, etc.

With embodiments of the systems and methods disclosed herein, the mobility of a target relay UE (e.g., the target relay UE for a Remote UE switching to indirect Relay UE procedure) is taken into account during the path switch procedure for a remote UE that is camping in a serving cell that is different from a serving cell of the target relay UE. In this regard, Figure 5 illustrates one example of an inter-gNB path switch procedure for a sidelink relay UE in accordance with a first embodiment of the present disclosure. As illustrated, the procedure of Figure 5 involves a remote UE 500, a relay UE 502, a source gNB 504, and a target gNB 506. In this embodiment, relay UE admission control is done before the source gNB 504 triggers the handover. As illustrated, the example procedure of Figure 5 includes the following steps:

• Step 508: The remote UE 500 sends a measurement report to the source gNB 504 (i.e., its serving gNB), and the source gNB 504 receives this measurement report from the remote UE 500. The measurement report includes a list of candidate relay UEs and, for each candidate relay UE, information (e.g., a serving cell ID of a serving cell of the candidate relay UE) that is used by the source gNB 504 to identify the gNB to which the candidate relay UE is connected.

• Step 510: The source gNB 504 selects a target relay UE for the path switch from the list of candidate relay UEs included in the measurement report received in step 508. In this example, the selected target relay UE is the relay UE 502. In this example, the serving cell of the selected target relay UE (i.e., the relay UE 502) is different from the serving cell of the remote UE 500. Further, the serving cell of the selected target relay UE (i.e., the relay UE 502) is controlled by, or belongs to, a different gNB, which in this example is the target gNB 506.

• Step 512: The source gNB 504, before triggering the handover procedure at the target gNB 506, sends a signaling (i.e., called a “Relay UE Enquiry” in this example) to the target gNB 506 that controls the serving cell of the selected target relay UE 502. In this signaling, the source gNB 504 may include information about the target relay UE 502 that has been selected for the path switch. Alternatively, this signaling may include a list of possible target relay UEs that are connected to the target gNB 508 (e.g., a subset of the candidate relay UEs included in the list contained in the measurement report of step 508 having serving cell(s) controlled by the target gNB 508).

• Step 514: The target gNB 506 receives the signaling (i.e., the Relay UE Enquiry) from the source gNB 504 in step 512, which indicates that a path switch procedure needs to be triggered together with the target relay UE 502 or a list of candidate relay UEs, or both. Upon receiving this signaling from the source gNB 504 in step 512, the target gNB 506 sends a signaling to the (candidate) target relay UE(s) 502. In this example, only one (candidate) target relay UE 502 is shown. This signaling is also referred to in this example as a “Relay UE Enquiry”. This signaling includes information that indicates that there is a path switch procedure that needs to be triggered (e.g., the cause of the signaling is a path switch) and/or information that indicates the remote UE 500 for which this path switch procedure is needed. This signaling is to check with the (candidate) target relay UE 502 about whether it is willing to act as relay UE (e.g., for the remote UE 500) or not. In other words, the signaling is to check with the (candidate) target relay UE 502 about whether it acknowledges to act as a relay UE (e.g., for the remote UE 500) or not.

• Step 516: The (candidate) target relay UE 502 receives the signaling from the target gNB 506 in step 514. Upon receiving the signaling from the target gNB 506 in step 514, the (candidate) target relay UE 502 replies back with a response that indicates whether or not the (candidate) target relay UE 502 acknowledges to act as a relay UE (e.g., for the remote UE 500). This response is sometimes referred to as indicating either a (positive) acknowledgment (in the case that the candidate target relay UE 502 acknowledges to act as a relay UE) or a negative acknowledgment (in the case that the candidate target relay UE 502 is not willing to act as a relay UE, i.e., the candidate target relay UE 502 does not acknowledge to act as a relay UE). In case of a negative acknowledgement, the (candidate) target relay UE 502 may also indicate a failure cause on why it is not willing to act as a relay UE.

• Step 518: Upon reception of the signaling back from the (candidate) target relay UE 502 in step 516, the target gNB 506 may perform at least one of the following actions:

(a) In case of a successful acknowledgement by the candidate target relay UE(s) 502, the target gNB 506 sends to the source gNB 504 a signaling (referred to in this example as a “Relay UE Enquiry Response”) that informs the source gNB 504 that the candidate target relay UE 502 acknowledges to act as a relay UE and that the path switch procedure can be triggered. This can be done via a simple indicator or via a new message itself, or both (new indicator in a new message).

(b) In case of a negative acknowledgement from the candidate relay UE 502, the target gNB 506 sends to the source gNB 504 a signaling (referred to in this example as the “Relay UE Enquiry Response”) that informs the source gNB 504 that the candidate target relay UE 502 is not willing to act as a relay UE and that the path switch procedure cannot be triggered (or should be aborted). This can be done via a simple indicator or via a new message itself, or both (new indicator in a new message).

(c) In case of negative acknowledgment from the candidate relay UE 502, when the target gNB 506 sends the signaling (referred to in this example as the “Relay UE Enquiry Response”) to the source gNB 504, it may also include a failure cause for describing why the path switch procedure cannot continue. In this case, what to do next is decided by the source gNB 504. In this case, the source gNB 504 can either abort the current path switch procedure or select a new target relay UE or a new target candidate cell, or simply send the remote UE to RRC IDLE/INACTIVE.

• Step 520: After receiving the signaling back from the target gNB 506 in step 518 (i.e., on whether the selected (candidate) target relay UE 502 is able to act as a relay UE, or which one of the relay UEs in the list are able to act as relay UEs), the source gNB 504 makes a decision on whether the handover procedure is to continue and, if so, which candidate relay UE is to be the target relay UE 502. In this example, the decision to continue the handover procedure to the target relay UE 502 is made and, as such, the source gNB 504 starts the handover procedure with the target gNB 506 by sending a handover request message for admission control of the target relay UE 502 to the target gNB 506.

• Step 522: After informing the source gNB 504 on whether the target relay UE 502 is able or not to act as a relay UE (i.e., the path switch procedure can be triggered), the target gNB 506 receives the handover request message from the source gNB 504 in step 520 and proceeds with admission control of the target relay UE 502.

• Step 524: After the admission control, the target gNB 506 sends a handover request acknowledgement message to the source gNB 504.

• Steps 526 - 534: The handover procedure continues, e.g., in the conventional manner. Figure 6 illustrates another example of an inter-gNB path switch procedure for a sidelink relay UE in accordance with a second embodiment of the present disclosure. As illustrated, the procedure of Figure 6 involves a remote UE 600, a relay UE 602, a source gNB 604, and a target gNB 606. In this embodiment, relay UE admission control is done after the source gNB 604 triggers the handover and before the target gNB 606 sends the acknowledgement. The steps of the procedure of Figure 6 are as follows:

• Step 608: The remote UE 600 sends a measurement report to the source gNB 604 (i.e., its serving gNB), and the source gNB 604 receives this measurement report from the remote UE 600. The measurement report includes a list of candidate relay UEs and, for each candidate relay UE, information (e.g., a serving cell ID of a serving cell of the candidate relay UE) that is used by the source gNB 604 to identify the gNB to which the candidate relay UE is connected.

• Step 610: The source gNB 604 selects a target relay UE for the path switch from the list of candidate relay UEs included in the measurement report received in step 608. In this example, the selected target relay UE is the relay UE 602. In this example, the serving cell of the selected target relay UE (i.e., the relay UE 602) is different from the serving cell of the remote UE 600. Further, the serving cell of the selected target relay UE (i.e., the relay UE 602) is controlled by, or belongs to, a different gNB, which in this example is the target gNB 606.

• Step 612: The source gNB 604 sends a handover request message for admission control of the target relay UE 602 to the target gNB 606. In this request, the source gNB 604 includes information that indicates the target relay UE 602 chosen for the path switch procedure or, alternatively, a list of candidate target relay UEs that are under the coverage of the target gNB 606 and that are potentially suitable for the path switch procedure.

• Step 614: The target gNB 606 receives the handover request message from the source gNB 604 in step 612. Upon the reception of this signaling from the source gNB 604, the target gNB 606 sends a signaling (referred to herein as a “Relay UE Enquiry”) to the candidate target relay UE(s) 602. In this example, only one candidate target relay UE 602 is shown. In such a signaling, it is indicated that there is a path switch procedure that needs to be triggered and which remote UE 600 is interested in this procedure. Also, this signaling is to check with the candidate target relay UE 602 on whether it acknowledges to act as a relay UE or not.

• Step 616: The candidate target relay UE 602 receives the signaling from the target gNB 606 in step 614. In this signaling, it can be indicated that the cause of this signaling is because of a path switch procedure and it can also be indicated who is the remote UE that need to be accommodated by the candidate target relay UE 602. Upon receiving this signaling from the target gNB 606, the candidate target relay UE 602 replies back with a response (referred to herein as a “Relay UE Enquiry Response”) that indicates whether or not the target relay UE 602 acknowledges to act as a relay UE. This response is sometimes referred to as indicating either a (positive) acknowledgment (in the case that the candidate target relay UE 602 acknowledges to act as a relay UE) or a negative acknowledgment (in the case that the candidate target relay UE 602 is not willing to act as a relay UE, i.e., in the case that the candidate target relay UE 602 does not acknowledge to act as a relay UE). In case of a negative acknowledgement, the candidate target relay UE 602 may also indicate a failure cause on why it is not willing to be a relay UE.

• Step 618: Upon a reception of the signaling back from the candidate target relay UE 602 in step 616, the target gNB 606 may perform at least one of the following actions: (a) In case of a successful acknowledgement by the candidate target relay UE(s) 602, the target gNB 606 sends to the source gNB 604 a signaling (i.e., the Handover Request Ack in this example) including information that informs the source gNB 604 that the candidate target relay UE 602 acknowledges to act as relay UE and that the path switch procedure can be triggered. This can be done via a simple indicator or via a new message itself, or both (new indicator in a new message). (b) In case of a negative acknowledgement from the candidate target relay UE 602, the target gNB sends to the source gNB 604 a signaling (i.e., the Handover Request Ack in this example) including information that informs the source gNB 604 that the candidate target relay UE 602 is not willing to act as a relay UE and that the path switch procedure cannot be triggered (or should be aborted). This can be done via a simple indicator or via a new message itself, or both (new indicator in a new message).

(c) In case of negative acknowledgment from the candidate target relay UE 602, when the target gNB 606 sends the signaling to the source gNB 604 in step 618, the target gNB 606 may also include a failure cause for describing why the path switch procedure cannot continue. In this case, what to do next is decided by the source gNB 604. In this case, the source gNB 604 can either abort the current path switch procedure or select a new target relay UE or a new target candidate cell, or simply send the remote UE to RRC IDLE/INACTIVE.

• After receiving the response signaling for the candidate relay UE(s) and after performing the admission control, the target gNB will send a handover request acknowledgement message to the source gNB by indicating whether the path switch can be executed or has failure. Eventually, if the path switch has failed (e.g., because the candidate target relay UE cannot act as relay UE in that moment), the target gNB indicates to the source gNB also a failure cause. Also, if there is more than one candidate relay UE that has given a positive acknowledgement to the target gNB, the target gNB may either send the full list to the source gNB and then is the source gNB who take the final decision on which candidate target relay UE to use or the target gNB can simply select the target relay UE and then inform the source gNB.

• Steps 620 - 630: After receiving a signaling back from the target gNB 606 (i.e., on whether the selected (candidate) target relay UE 602 is able to act as relay UE, or which one of the relay UEs in the list are able to act as relay UEs), the source gNB 604 makes a decision on whether to continue handover procedure and, if so, which candidate relay UE is to be the target relay UE 602. In this example, the decision to continue the handover procedure to the target relay UE 602 is made and, as such, the source gNB 604 continues the handover procedure, e.g., in the conventional manner.

A non-limiting example is provided below for the possible specification change over XnAP (3GPP TS 38.423). This non-limiting example is applicable to both the embodiment of Figure 5 and the embodiment of Figure 6. ***** START POSSIBLE SPECIFICATION CHANGE *****

9.1.1.x Relay UE Enquiry (TS 38.423)

This message is sent by the source NG-RAN node to the target NG-RAN node to enquiry the relay UE for sidelink transmission.

Direction: source NG-RAN node

target NG-RAN node.

9.1.1.y Relay UE Enquiry Result (TS 38.423) This message is sent by the target NG-RAN node to the source NG-RAN node to report the enquiry result of the candidate relay UE for sidelink transmission.

Direction: target NG-RAN node

source NG-RAN node.

***** END POSSIBLE SPECIFICATION CHANGE *****

In one embodiment, the signaling between the remote UE 500 or 600 and the relay UE

502 or 602 and the network (e.g., the source gNB 504 or 604 or the target gNB 506 or 606) and the signaling between two the source gNB 504 or 604 and the target gNB 506 or 606 can be done according to the following cases.

For signalins between remote/relay UE:

• Option a-1: Dedicated higher layer signaling (e.g., dedicated Radio Resource Control (RRC) signaling), which may be an existing signaling (e.g., existing RRC signaling) or a new signaling (e.g., new RRC signaling).

• Option a-2: Medium Access Control (MAC) Control Element (CE) based signaling, which may be an existing MAC CE or a new MAC CE for carrying the signaling.

• Option a-3: The UE initiates a Random Access Channel (RACH) procedure to carry the signaling. The signaling could be a RACH-scheduling request (SR) message.

In one embodiment, a 4-step Random Access (RA) can be triggered to carry the signaling. In an example, Msgl of the 4-step RA procedure is used to carry the signaling. A dedicated preamble or dedicated RACH occasions may be allocated to the UE for indicating the above signaling information. The allocation may be pre-defined, determined based on a pre-defined rule, or configured by another node. In another example, Msg3 of the 4-step RA procedure is extended to carry the signaling information. In Msg3, the UE MAC entity adds an indicator indicating the above signaling information. The indicator may be a field in the MAC subheader or carried in a MAC CE.

In another embodiment, a 2-step RA can be triggered to carry the signaling. A dedicated preamble or dedicated RACH occasions or dedicated Physical Uplink Shared Channel (PUSCH) occasions/resources may be allocated to the UE for indicating the signaling information. Alternatively, indicators can be included in MsgA payload. The indicator may be a field in the MAC subheader or carried in a MAC CE.

Alternatively, an RRC message (partly or fully) may be included in a RACH message, which includes the above signaling information from the UE.

• Option a-4: the UE initiates a Physical Uplink Control Channel (PUCCH) transmission for indicting the signaling information. Separate dedicated PUCCH resources may be configured to the UE accordingly. The signaling could be a PUCCH-scheduling request (SR) message.

• Option a-5: the UE initiates a configured grant-based transmission for carrying the signaling. Separate dedicated configured grant resources may be configured accordingly. Alternatively, the signaling information may be included in the Configured Grant Uplink Control Information (CG-UCI). Specifically, as an additional example to Option a-4 and Option a-5, the UE can transmit the signaling in the PUCCH-Uplink Control Information (UCI) which can be carried in the PUCCH or multiplexed with PUSCH.

In an example, the UE may transmit an SR or Buffer Status Report (BSR) on the direct path to the gNB for indicating that the UE prefers to perform transmission or reception using the direct path from now on.

For signaling from remote UE to the network via the relay UE:

• Option b-1: Dedicated Uu RRC signaling, which may be an existing RRC signaling or a new RRC signaling. The UE maintains an End-to-End (E2E) connection to the gNB via a L2 relay UE; therefore, the UE can send a Uu RRC signaling to the gNB via the relay UE.

• Option b-2: two-hop signaling o The UE first sends the signaling to the relay UE via PC5 interface using one of the following signaling

■ RRC signaling (i.e., PC5 RRC)

■ PC5-S signaling

■ Discovery message

■ Control PDU of a protocol layer such as PDCP, RLC, or an adaptation layer

■ MAC CE

■ LI signaling on physical channels including PSSCH, PSCCH, PSFCH, or a new physical channel

• Scheduling request (SR) may be introduced on SL. A SR may be transmitted on one of the above physical channels or a new physical channel. The UE can therefore transmit an SR to the relay UE for indicating that the UE prefers to perform transmission or reception using the indirect path from now on. o After the relay UE receives the signaling from the UE, the relay UE forwards the signaling to the gNB via Uu interface using one of the following signaling

■ dedicated RRC signaling.

■ Control PDU of a protocol layer such as PDCP, RLC, or an adaptation layer

■ MAC CE based signaling.

■ a RACH procedure to carry the signaling, e.g., RACH-SR signaling. ■ a PUCCH transmission for indicting the signaling information, e.g., PUCCH-SR signaling.

■ a configured grant-based transmission for carrying the signaling.

• Inter-node RRC signaling

• X2/Xn signaling

• Fl signaling

Figure 7 shows an example of a communication system 700 in accordance with some embodiments.

In the example, the communication system 700 includes a telecommunication network 702 that includes an access network 704, such as a Radio Access Network (RAN), and a core network 706, which includes one or more core network nodes 708. The access network 704 includes one or more access network nodes, such as network nodes 710A and 710B (one or more of which may be generally referred to as network nodes 710), or any other similar Third Generation Partnership Project (3GPP) access node or non-3GPP Access Point (AP). The network nodes 710 facilitate direct or indirect connection of User Equipment (UE), such as by connecting UEs 712A, 712B, 712C, and 712D (one or more of which may be generally referred to as UEs 712) to the core network 706 over one or more wireless connections.

Example wireless communications over a wireless connection include transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 700 may include any number of wired or wireless networks, network nodes, UEs, 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. The communication system 700 may include and/or interface with any type of communication, telecommunication, data, cellular, radio network, and/or other similar type of system.

The UEs 712 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and/or operable to communicate wirelessly with the network nodes 710 and other communication devices. Similarly, the network nodes 710 are arranged, capable, configured, and/or operable to communicate directly or indirectly with the UEs 712 and/or with other network nodes or equipment in the telecommunication network 702 to enable and/or provide network access, such as wireless network access, and/or to perform other functions, such as administration in the telecommunication network 702. In the depicted example, the core network 706 connects the network nodes 710 to one or more hosts, such as host 716. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 706 includes one more core network nodes (e g., core network node 708) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and/or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 708. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-Concealing Function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and/or a User Plane Function (UPF).

The host 716 may be under the ownership or control of a service provider other than an operator or provider of the access network 704 and/or the telecommunication network 702 and may be operated by the service provider or on behalf of the service provider. The host 716 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio/video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

As a whole, the communication system 700 of Figure 7 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system 700 may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and/or other suitable Second, Third, Fourth, or Fifth Generation (2G, 3G, 4G, or 5G) standards, or any applicable future generation standard (e.g., Sixth Generation (6G)); Wireless Local Area Network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and/or any Low Power Wide Area Network (LPWAN) standards such as LoRa and Sigfox. In some examples, the telecommunication network 702 is a cellular network that implements 3 GPP standardized features. Accordingly, the telecommunication network 702 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 702. For example, the telecommunication network 702 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing enhanced Mobile Broadband (eMBB) services to other UEs, and/or massive Machine Type Communication (mMTC)/massive Internet of Things (loT) services to yet further UEs.

In some examples, the UEs 712 are configured to transmit and/or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 704 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 704. Additionally, a UE may be configured for operating in single- or multi -Radio Access Technology (RAT) or multi-standard mode. For example, a UE may operate with any one or combination of WiFi, New Radio (NR), and LTE, i.e., be configured for Multi-Radio Dual Connectivity (MR-DC), such as Evolved UMTS Terrestrial RAN (E-UTRAN) NR - Dual Connectivity (EN-DC)

In the example, a hub 714 communicates with the access network 704 to facilitate indirect communication between one or more UEs (e g., UE 712C and/or 712D) and network nodes (e.g., network node 710B). In some examples, the hub 714 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 714 may be a broadband router enabling access to the core network 706 for the UEs. As another example, the hub 714 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 710, or by executable code, script, process, or other instructions in the hub 714. As another example, the hub 714 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 714 may be a content source. For example, for a UE that is a Virtual Reality (VR) headset, display, loudspeaker or other media delivery device, the hub 714 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 714 then provides to the UE either directly, after performing local processing, and/or after adding additional local content. In still another example, the hub 714 acts as a proxy server or orchestrator for the UEs, in particular in if one or more of the UEs are low energy loT devices. The hub 714 may have a constant/persistent or intermittent connection to the network node 710B. The hub 714 may also allow for a different communication scheme and/or schedule between the hub 714 and UEs (e.g., UE 712C and/or 712D), and between the hub 714 and the core network 706. In other examples, the hub 714 is connected to the core network 706 and/or one or more UEs via a wired connection. Moreover, the hub 714 may be configured to connect to a Machine-to-Machine (M2M) service provider over the access network 704 and/or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 710 while still connected via the hub 714 via a wired or wireless connection. In some embodiments, the hub 714 may be a dedicated hub - that is, a hub whose primary function is to route communications to/from the UEs from/to the network node 710B. In other embodiments, the hub 714 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and the network node 710B, but which is additionally capable of operating as a communication start and/or end point for certain data channels.

Figure 8 shows a UE 800 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged, and/or operable to communicate wirelessly with network nodes and/or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, Voice over Internet Protocol (VoIP) phone, wireless local loop phone, desktop computer, Personal Digital Assistant (PDA), wireless camera, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, Laptop Embedded Equipment (LEE), Laptop Mounted Equipment (LME), smart device, wireless Customer Premise Equipment (CPE), vehicle-mounted or vehicle embedded/integrated wireless device, etc. Other examples include any UE identified by the 3GPP, including a Narrowband Internet of Things (NB-IoT) UE, a Machine Type Communication (MTC) UE, and/or an enhanced MTC (eMTC) UE.

A UE may support Device-to-Device (D2D) communication, for example by implementing a 3 GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I), or Vehicle- to-Everything (V2X). In other examples, a 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).

The UE 800 includes processing circuitry 802 that is operatively coupled via a bus 804 to an input/output interface 806, a power source 808, memory 810, a communication interface 812, and/or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 8. 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.

The processing circuitry 802 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 810. The processing circuitry 802 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, 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 802 may include multiple Central Processing Units (CPUs).

In the example, the input/output interface 806 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and/or output devices Examples of an output device include 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. An input device may allow a user to capture information into the UE 800. Examples of an input device 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, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

In some embodiments, the power source 808 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 808 may further include power circuitry for delivering power from the power source 808 itself, and/or an external power source, to the various parts of the UE 800 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging the power source 808. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 808 to make the power suitable for the respective components of the UE 800 to which power is supplied.

The memory 810 may be or be configured to include memory such as Random Access Memory (RAM), Read Only Memory (ROM), Programmable ROM (PROM), Erasable PROM (EPROM), Electrically EPROM (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 810 includes one or more application programs 814, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 816. The memory 810 may store, for use by the UE 800, any of a variety of various operating systems or combinations of operating systems.

The memory 810 may be configured to include a number of physical drive units, such as Redundant Array of Independent Disks (RAID), 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 disk drive, Blu-Ray optical disc drive, Holographic Digital Data Storage (HDDS) optical disc drive, external mini Dual In-line Memory Module (DIMM), Synchronous Dynamic RAM (SDRAM), external micro-DIMM SDRAM, smartcard memory such as a tamper resistant module in the form of a Universal Integrated Circuit Card (UICC) including one or more Subscriber Identity Modules (SIMs), such as a Universal SIM (USIM) and/or Internet Protocol Multimedia Services Identity Module (ISIM), other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as a ‘SIM card.’ The memory 810 may allow the UE 800 to access instructions, application programs, and 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 as or in the memory 810, which may be or comprise a device-readable storage medium.

The processing circuitry 802 may be configured to communicate with an access network or other network using the communication interface 812. The communication interface 812 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 822. The communication interface 812 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 818 and/or a receiver 820 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 818 and receiver 820 may be coupled to one or more antennas (e.g., the antenna 822) and may share circuit components, software, or firmware, or alternatively be implemented separately.

In the illustrated embodiment, communication functions of the communication interface 812 may include cellular communication, WiFi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, NFC, 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. Communications may be implemented according to one or more communication protocols and/or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband CDMA (WCDMA), GSM, LTE, NR, UMTS, WiMax, Ethernet, Transmission Control Protocol/Internet Protocol (TCP/IP), Synchronous Optical Networking (SONET), Asynchronous Transfer Mode (ATM), Quick User Datagram Protocol Internet Connection (QUIC), Hypertext Transfer Protocol (HTTP), and so forth.

Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 812, or via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected, an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

As another example, a UE comprises an actuator, a motor, or a switch related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

A UE, when in the form of an loT device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application, and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a television, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door/window sensor, a flood/moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or VR, a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or itemtracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and/or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE 800 shown in Figure 8.

As yet another specific example, in an loT scenario, a UE 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 UE and/or a network node. The UE may in this case be an M2M device, which may in a 3 GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3 GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship, an airplane, or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g., by controlling an actuator) to increase or decrease the drone’s speed. The first and/or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator and handle communication of data for both the speed sensor and the actuators.

Figure 9 shows a network node 900 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged, and/or operable to communicate directly or indirectly with a UE and/or with other network nodes or equipment in a telecommunication network. Examples of network nodes include, but are not limited to, APs (e.g., radio APs), Base Stations (BSs) (e.g., radio BSs, Node Bs, evolved Node Bs (eNBs), and NR Node Bs (gNBs)). BSs may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto BSs, pico BSs, micro BSs, or macro BSs. A BS 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 BS such as centralized digital units and/or Remote Radio Units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such RRUs may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio BS may also be referred to as nodes in a Distributed Antenna System (DAS).

Other examples of network nodes include multiple Transmission Point (multi-TRP) 5G access nodes, Multi -Standard Radio (MSR) equipment such as MSR BSs, network controllers such as Radio Network Controllers (RNCs) or BS Controllers (BSCs), Base Transceiver Stations (BTSs), transmission points, transmission nodes, Multi-Cell/Multicast Coordination Entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and/or Minimization of Drive Tests (MDTs).

The network node 900 includes processing circuitry 902, memory 904, a communication interface 906, and a power source 908. The network node 900 may be composed of multiple physically separate components (e.g., a Node B component and an RNC component, or a BTS component and a BSC component, etc ), which may each have their own respective components. In certain scenarios in which the network node 900 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 Node Bs. In such a scenario, each unique Node B and RNC pair may in some instances be considered a single separate network node. In some embodiments, the network node 900 may be configured to support multiple RATs. In such embodiments, some components may be duplicated (e.g., separate memory 904 for different RATs) and some components may be reused (e.g., an antenna 910 may be shared by different RATs). The network node 900 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 900, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, Long Range Wide Area Network (LoRaWAN), Radio Frequency Identification (RFID), or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within the network node 900.

The processing circuitry 902 may comprise a combination of one or more of a microprocessor, controller, microcontroller, CPU, DSP, ASIC, FPGA, 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 900 components, such as the memory 904, to provide network node 900 functionality.

In some embodiments, the processing circuitry 902 includes a System on a Chip (SOC). In some embodiments, the processing circuitry 902 includes one or more of Radio Frequency (RF) transceiver circuitry 912 and baseband processing circuitry 914. In some embodiments, the RF transceiver circuitry 912 and the baseband processing circuitry 914 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 the RF transceiver circuitry 912 and the baseband processing circuitry 914 may be on the same chip or set of chips, boards, or units.

The memory 904 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, RAM, 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 the processing circuitry 902. The memory 904 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and/or other instructions capable of being executed by the processing circuitry 902 and utilized by the network node 900. The memory 904 may be used to store any calculations made by the processing circuitry 902 and/or any data received via the communication interface 906. In some embodiments, the processing circuitry 902 and the memory 904 are integrated.

The communication interface 906 is used in wired or wireless communication of signaling and/or data between a network node, access network, and/or UE. As illustrated, the communication interface 906 comprises port(s)/terminal(s) 916 to send and receive data, for example to and from a network over a wired connection. The communication interface 906 also includes radio front-end circuitry 918 that may be coupled to, or in certain embodiments a part of, the antenna 910. The radio front-end circuitry 918 comprises filters 920 and amplifiers 922. The radio front-end circuitry 918 may be connected to the antenna 910 and the processing circuitry 902. The radio front-end circuitry 918 may be configured to condition signals communicated between the antenna 910 and the processing circuitry 902. The radio front-end circuitry 918 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 918 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of the filters 920 and/or the amplifiers 922. The radio signal may then be transmitted via the antenna 910. Similarly, when receiving data, the antenna 910 may collect radio signals which are then converted into digital data by the radio front-end circuitry 918. The digital data may be passed to the processing circuitry 902. In other embodiments, the communication interface 906 may comprise different components and/or different combinations of components.

In certain alternative embodiments, the network node 900 does not include separate radio front-end circuitry 918; instead, the processing circuitry 902 includes radio front-end circuitry and is connected to the antenna 910. Similarly, in some embodiments, all or some of the RF transceiver circuitry 912 is part of the communication interface 906. In still other embodiments, the communication interface 906 includes the one or more ports or terminals 916, the radio frontend circuitry 918, and the RF transceiver circuitry 912 as part of a radio unit (not shown), and the communication interface 906 communicates with the baseband processing circuitry 914, which is part of a digital unit (not shown).

The antenna 910 may include one or more antennas, or antenna arrays, configured to send and/or receive wireless signals. The antenna 910 may be coupled to the radio front-end circuitry 918 and may be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. In certain embodiments, the antenna 910 is separate from the network node 900 and connectable to the network node 900 through an interface or port.

The antenna 910, the communication interface 906, and/or the processing circuitry 902 may be configured to perform any receiving operations and/or certain obtaining operations described herein as being performed by the network node 900. Any information, data, and/or signals may be received from a UE, another network node, and/or any other network equipment. Similarly, the antenna 910, the communication interface 906, and/or the processing circuitry 902 may be configured to perform any transmitting operations described herein as being performed by the network node 900. Any information, data, and/or signals may be transmitted to a UE, another network node, and/or any other network equipment.

The power source 908 provides power to the various components of the network node 900 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 908 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 900 with power for performing the functionality described herein. For example, the network node 900 may be connectable to an external power source (e.g., the power grid or an electricity outlet) via input circuitry or an interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 908. As a further example, the power source 908 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

Embodiments of the network node 900 may include additional components beyond those shown in Figure 9 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, the network node 900 may include user interface equipment to allow input of information into the network node 900 and to allow output of information from the network node 900. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 900.

Figure 10 is a block diagram of a host 1000, which may be an embodiment of the host 716 of Figure 7, in accordance with various aspects described herein. As used herein, the host 1000 may be or comprise various combinations of hardware and/or software including a standalone server, a blade server, a cloud-implemented server, a distributed server, a virtual machine, container, or processing resources in a server farm. The host 1000 may provide one or more services to one or more UEs.

The host 1000 includes processing circuitry 1002 that is operatively coupled via a bus 1004 to an input/output interface 1006, a network interface 1008, a power source 1010, and memory 1012. Other components may be included in other embodiments. Features of these components may be substantially similar to those described with respect to the devices of previous figures, such as Figures 8 and 9, such that the descriptions thereof are generally applicable to the corresponding components of the host 1000.

The memory 1012 may include one or more computer programs including one or more host application programs 1014 and data 1016, which may include user data, e.g., data generated by a UE for the host 1000 or data generated by the host 1000 for a UE. Embodiments of the host 1000 may utilize only a subset or all of the components shown. The host application programs 1014 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (VVC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), Moving Picture Experts Group (MPEG), VP9) and audio codecs (e.g., Free Lossless Audio Codec (FLAG), Advanced Audio Coding (AAC), MPEG, G.711), including transcoding for multiple different classes, types, or implementations of UEs (e.g., handsets, desktop computers, wearable display systems, and heads-up display systems). The host application programs 1014 may also provide for user authentication and licensing checks and may periodically report health, routes, and content availability to a central node, such as a device in or on the edge of a core network. Accordingly, the host 1000 may select and/or indicate a different host for Over-The-Top (OTT) services for a UE. The host application programs 1014 may support various protocols, such as the HTTP Live Streaming (HLS) protocol, Real-Time Messaging Protocol (RTMP), Real-Time Streaming Protocol (RTSP), Dynamic Adaptive Streaming over HTTP (DASH or MPEG-DASH), etc.

Figure 11 is a block diagram illustrating a virtualization environment 1100 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 any device described herein, 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. Some or all of the functions described herein may be implemented as virtual components executed by one or more Virtual Machines (VMs) implemented in one or more virtual environments 1100 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized.

Applications 1102 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and/or benefits of some of the embodiments disclosed herein.

Hardware 1104 includes processing circuitry, memory that stores software and/or instructions executable by hardware processing circuitry, and/or other hardware devices as described herein, such as a network interface, input/output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1106 (also referred to as hypervisors or VM Monitors (VMMs)), provide VMs 1108A and 1108B (one or more of which may be generally referred to as VMs 1108), and/or perform any of the functions, features, and/or benefits described in relation with some embodiments described herein. The virtualization layer 1106 may present a virtual operating platform that appears like networking hardware to the VMs 1108.

The VMs 1108 comprise virtual processing, virtual memory, virtual networking, or interface and virtual storage, and may be run by a corresponding virtualization layer 1106. Different embodiments of the instance of a virtual appliance 1102 may be implemented on one or more of the VMs 1108, and the implementations may be made in different ways. 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, a VM 1108 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 the VMs 1108, and that part of the hardware 1104 that executes that VM, be it hardware dedicated to that VM and/or hardware shared by that VM with others of the VMs 1108, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1108 on top of the hardware 1104 and corresponds to the application 1102.

The hardware 1104 may be implemented in a standalone network node with generic or specific components. The hardware 1104 may implement some functions via virtualization. Alternatively, the hardware 1104 may be part of a larger cluster of hardware (e.g., such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1110, which, among others, oversees lifecycle management of the applications 1102. In some embodiments, the hardware 1104 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes 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 RAN or a BS. In some embodiments, some signaling can be provided with the use of a control system 1112 which may alternatively be used for communication between hardware nodes and radio units.

Figure 12 shows a communication diagram of a host 1202 communicating via a network node 1204 with a UE 1206 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as the UE 712A of Figure 7 and/or the UE 800 of Figure 8), the network node (such as the network node 710A of Figure 7 and/or the network node 900 of Figure 9), and the host (such as the host 716 of Figure 7 and/or the host 1000 of Figure 10) discussed in the preceding paragraphs will now be described with reference to Figure 12.

Like the host 1000, embodiments of the host 1202 include hardware, such as a communication interface, processing circuitry, and memory. The host 1202 also includes software, which is stored in or is accessible by the host 1202 and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as the UE 1206 connecting via an OTT connection 1250 extending between the UE 1206 and the host 1202. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection 1250.

The network node 1204 includes hardware enabling it to communicate with the host 1202 and the UE 1206 via a connection 1260. The connection 1260 may be direct or pass through a core network (like the core network 706 of Figure 7) and/or one or more other intermediate networks, such as one or more public, private, or hosted networks. For example, an intermediate network may be a backbone network or the Internet.

The UE 1206 includes hardware and software, which is stored in or accessible by the UE 1206 and executable by the UE’s processing circuitry. The software includes a client application, such as a web browser or operator-specific “app” that may be operable to provide a service to a human or non-human user via the UE 1206 with the support of the host 1202. In the host 1202, an executing host application may communicate with the executing client application via the OTT connection 1250 terminating at the UE 1206 and the host 1202. In providing the service to the user, the UE's client application may receive request data from the host's host application and provide user data in response to the request data. The OTT connection 1250 may transfer both the request data and the user data. The UE's client application may interact with the user to generate the user data that it provides to the host application through the OTT connection 1250.

The OTT connection 1250 may extend via the connection 1260 between the host 1202 and the network node 1204 and via a wireless connection 1270 between the network node 1204 and the UE 1206 to provide the connection between the host 1202 and the UE 1206. The connection 1260 and the wireless connection 1270, over which the OTT connection 1250 may be provided, have been drawn abstractly to illustrate the communication between the host 1202 and the UE 1206 via the network node 1204, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

As an example of transmitting data via the OTT connection 1250, in step 1208, the host 1202 provides user data, which may be performed by executing a host application. In some embodiments, the user data is associated with a particular human user interacting with the UE 1206. In other embodiments, the user data is associated with a UE 1206 that shares data with the host 1202 without explicit human interaction. In step 1210, the host 1202 initiates a transmission carrying the user data towards the UE 1206. The host 1202 may initiate the transmission responsive to a request transmitted by the UE 1206. The request may be caused by human interaction with the UE 1206 or by operation of the client application executing on the UE 1206. The transmission may pass via the network node 1204 in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step 1212, the network node 1204 transmits to the UE 1206 the user data that was carried in the transmission that the host 1202 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1214, the UE 1206 receives the user data carried in the transmission, which may be performed by a client application executed on the UE 1206 associated with the host application executed by the host 1202.

In some examples, the UE 1206 executes a client application which provides user data to the host 1202. The user data may be provided in reaction or response to the data received from the host 1202. Accordingly, in step 1216, the UE 1206 may provide user data, which may be performed by executing the client application. In providing the user data, the client application may further consider user input received from the user via an input/output interface of the UE 1206. Regardless of the specific manner in which the user data was provided, the UE 1206 initiates, in step 1218, transmission of the user data towards the host 1202 via the network node 1204. In step 1220, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 1204 receives user data from the UE 1206 and initiates transmission of the received user data towards the host 1202. In step 1222, the host 1202 receives the user data carried in the transmission initiated by the UE 1206.

One or more of the various embodiments improve the performance of OTT services provided to the UE 1206 using the OTT connection 1250, in which the wireless connection 1270 forms the last segment.

In an example scenario, factory status information may be collected and analyzed by the host 1202. As another example, the host 1202 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host 1202 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, the host 1202 may store surveillance video uploaded by a UE. As another example, the host 1202 may store or control access to media content such as video, audio, VR, or AR which it can broadcast, multicast, or unicast to UEs. As other examples, the host 1202 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing, and/or transmitting data.

In some examples, 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 the OTT connection 1250 between the host 1202 and the UE 1206 in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 1250 may be implemented in software and hardware of the host 1202 and/or the UE 1206. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection 1250 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or by supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 1250 may include message format, retransmission settings, preferred routing, etc.; the reconfiguring need not directly alter the operation of the network node 1204. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency, and the like by the host 1202. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 1250 while monitoring propagation times, errors, etc.

Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components It is to be understood that these computing devices may comprise any suitable combination of hardware and/or software needed to perform the tasks, features, functions, and methods disclosed herein. Determining, calculating, obtaining, or similar operations described herein may be performed by processing circuitry, which may process information 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. Moreover, while components are depicted as single boxes located within a larger box or nested within multiple boxes, in practice computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and/or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device- readable storage medium, such as in a hardwired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device but are enjoyed by the computing device as a whole and/or by end users and a wireless network generally.

Some example embodiments of the present disclosure are as follows:

Group A Embodiments

Embodiment 1 : A method performed by a candidate target relay User Equipment, UE, (502; 602), the method comprising:

• receiving (514; 614), from a target network node (506; 606) for a handover of a remote UE (500; 600) in association with a path switch procedure in which the candidate target relay UE (502; 602) is a candidate target relay UE for the path switch procedure, a message that enquires as to whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and

• sending (516; 616), to the target network node (506; 606), a response that comprises information that indicates whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE.

Embodiment 2: The method of embodiment 1 wherein a serving cell of the candidate target relay UE (502; 602) is controlled by a source network node (504; 604) for the handover and is different than a serving cell of the target relay UE (502; 604) which is controlled by the target network node (506; 606).

Embodiment 3 : The method of embodiment 1 or 2 wherein the steps of receiving and sending are performed prior to triggering of the handover of the remote UE (500; 600) from the source network node (504; 604) to the target network node (506; 606). Embodiment 4: The method of embodiment 1 or 2 wherein the steps of receiving and sending are performed after triggering of the handover of the remote UE (500; 600) from the source network node (504; 604) to the target network node (506; 606) but before the target network node (506; 606) sends a handover request acknowledgement to the source network node (504; 604).

Embodiment 5: The method of any of the previous embodiments, further comprising: providing user data; and forwarding the user data to a host via the transmission to the network node.

Group B Embodiments

Embodiment 6: A method performed by a source network node (504; 604), the method comprising:

• selecting (510; 610) one or more candidate target relay UEs for a path switch procedure for a remote User Equipment, UE, (500; 600), the one or more candidate target relay UEs each having a serving cell that is: (a) different than a serving cell of the remote UE (500) and (b) controlled by a target network node (506; 606), the target network node (506; 606) being a network node other than the source network node (504; 604);

• sending (512; 612), to the target network node (506; 606), a message comprising information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (500; 600); and

• receiving (518; 618), from the target network node (506; 606), a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

Embodiment 7: The method of embodiment 6 further comprising:

• receiving (508; 608), from the remote UE (500; 600), a report comprising a list of candidate relay UEs;

• wherein selecting (510; 610) the one or more candidate target relay UEs for the path switch procedure for the remote UE (500; 600) comprises selecting (510; 610) the one or more candidate target relay UEs for the path switch procedure for the remote UE (500; 600) from the list of candidate relay UEs.

Embodiment 8: The method of embodiment 7 wherein the report received from the remote UE (500; 600) further comprises for each candidate relay UE in the list, information that indicates a serving cell of the candidate relay UE. Embodiment 9: The method of any of embodiments 6 to 8 wherein:

• the response received from the target network node comprises information that indicates that the one or more candidate target relay UEs acknowledge to act as a relay UE; and

• the method further comprises, responsive to the response comprising the information that indicates that the one or more candidate target relay UEs acknowledge to act as a relay UE, performing one or more actions (520, 526, 528; 620-624) to complete handover of the remote UE (500; 600) to the target gNB (506; 606) and a path switch for the remote UE (500; 600) such that the remote UE (500; 600) communicates with the target gNB (506; 606) via a relay UE (502; 602), the relay UE (502; 602) being one of the one or more candidate target relay UEs.

Embodiment 10: The method of any of embodiments 6 to 9 wherein sending (512), to the target network node (506), the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (500) comprises sending (512) the message to the target network node (506) prior to triggering a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

Embodiment 11 : The method of embodiment 10 wherein receiving (518), from the target network node (506), the response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE comprises receiving (518) the response from the target network node (506) prior to triggering a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

Embodiment 12: The method of embodiment 11 wherein:

• the method further comprises, responsive to the response comprising the information that indicates that the one or more candidate target relay UEs acknowledge to act as a relay UE, sending (520) a handover request to the target network node (506) to initiate a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

Embodiment 13 : The method of any of embodiments 6 to 9 wherein sending (612), to the target network node (606), the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (600) comprises sending (612) the message to the target network node (606) at the time of or after triggering a handover procedure for handover of the remote UE (600) from the source network node (604) to the target network node (606) but before the target network node (606) responds with a handover acknowledgment.

Embodiment 14: The method of embodiment 13 wherein the message sent to the target network node (606) is a handover request.

Embodiment 15: The method of embodiment 13 or 14 wherein receiving (618), from the target network node (606), the response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE comprises receiving (618) a handover request acknowledgment from the target network node (606), the handover request acknowledgment comprising the information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

Embodiment 16: The method of any of embodiments 13 to 15 wherein:

• the method further comprises, responsive to the response comprising the information that indicates that the one or more candidate target relay UEs acknowledge to act as a relay UE, performing one or more actions (620-24) for a path switch procedure for the remote UE (600) such that the remote UE (600) communicates with the target gNB (606) via a relay UE (602), the relay UE (602) being one of the one or more candidate target relay UEs.

Embodiment 17: A method performed by a target network node (506; 606), the method comprising:

• receiving (512; 612), from a source network node (504; 604), a message comprising information that indicates one or more candidate target relay User Equipments, UEs, for a path switch procedure for a remote UE (500; 600);

• for each candidate target relay UE (502; 602) from the one or more candidate target relay UEs indicated in the message received from the source network node (504;

604): o sending (514; 614), to the candidate target relay UE (502; 602), a message that enquires as to whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and o receiving (516; 616), from the candidate target relay UE (502; 602), a response that comprises information that indicates whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and

• sending (518; 618), to the source network node (504; 604), a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE, based on the response(s) received from the one or more candidate target relay UEs.

Embodiment 18: The method of embodiment 17 wherein receiving (512), from the source network node (504), the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (500) comprises receiving (512) the message from the source network node (504) prior to receiving a message that triggers a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

Embodiment 19: The method of embodiment 18 wherein sending (518), to the source network node (504), the response comprising information that indicates whether the one or more candidate target relay UEs acknowledge to act as a relay UE comprises sending (518) the response to the source network node (504) prior to receiving a message that triggers a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

Embodiment 20: The method of embodiment 18 or 19 wherein:

• the response sent to the source network node comprises information that indicates that the one or more candidate target relay UEs acknowledge to act as a relay UE; and

• the method further comprises receiving (520) a handover request from the source network node (504) to initiate a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

Embodiment 21 : The method of embodiment 17 wherein receiving (612), from the source network node (604), the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (600) comprises receiving (612) the message from the source network node (604) at the time of or after triggering of a handover procedure for handover of the remote UE (600) from the source network node (604) to the target network node (606) but before the target network node (606) responds to the source network node (604) with a handover acknowledgment.

Embodiment 22: The method of embodiment 21 wherein the message received from the source network node (606) is a handover request. Embodiment 23 : The method of embodiment 21 or 22 wherein sending (618), to the source network node (604), the response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE comprises sending (618) a handover request acknowledgment to the source network node (604), the handover request acknowledgment comprising the information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

Embodiment 24: The method of any of the previous embodiments, further comprising: obtaining user data; and forwarding the user data to a host or a user equipment.

Group C Embodiments

Embodiment 25 : A user equipment comprising:

• processing circuitry configured to perform any of the steps of any of the Group A embodiments; and

• power supply circuitry configured to supply power to the processing circuitry.

Embodiment 26: A network node comprising:

• processing circuitry configured to perform any of the steps of any of the Group B embodiments;

Embodiment 27 : A user equipment (UE) comprising:

• an antenna configured to send and receive wireless signals;

• radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry;

• the processing circuitry being configured to perform any of the steps of any of the Group A embodiments;

• an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry;

• an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and

• a battery connected to the processing circuitry and configured to supply power to the UE.

Embodiment 28: A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising:

• processing circuitry configured to provide user data; and • a network interface configured to initiate transmission of the user data to a cellular network for transmission to a user equipment (UE),

• wherein the UE comprises a communication interface and processing circuitry, the communication interface and processing circuitry of the UE being configured to perform any of the steps of any of the Group A embodiments to receive the user data from the host.

Embodiment 29: The host of the previous embodiment, wherein the cellular network further includes a network node configured to communicate with the UE to transmit the user data to the UE from the host.

Embodiment 30: The host of the previous 2 embodiments, wherein:

• the processing circuitry of the host is configured to execute a host application, thereby providing the user data; and

• the host application is configured to interact with a client application executing on the UE, the client application being associated with the host application.

Embodiment 31 : A method implemented by a host operating in a communication system that further includes a network node and a user equipment (UE), the method comprising: providing user data for the UE; and

• initiating a transmission carrying the user data to the UE via a cellular network comprising the network node, wherein the UE performs any of the operations of any of the Group A embodiments to receive the user data from the host.

Embodiment 32: The method of the previous embodiment, further comprising:

• at the host, executing a host application associated with a client application executing on the UE to receive the user data from the UE.

Embodiment 33 : The method of the previous embodiment, further comprising:

• at the host, transmitting input data to the client application executing on the UE, the input data being provided by executing the host application,

• wherein the user data is provided by the client application in response to the input data from the host application.

Embodiment 34: A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising:

• processing circuitry configured to provide user data; and

• a network interface configured to initiate transmission of the user data to a cellular network for transmission to a user equipment (UE),

• wherein the UE comprises a communication interface and processing circuitry, the communication interface and processing circuitry of the UE being configured to perform any of the steps of any of the Group A embodiments to transmit the user data to the host.

Embodiment 35: The host of the previous embodiment, wherein the cellular network further includes a network node configured to communicate with the UE to transmit the user data from the UE to the host.

Embodiment 36: The host of the previous 2 embodiments, wherein:

Embodiment 37: A method implemented by a host configured to operate in a communication system that further includes a network node and a user equipment (UE), the method comprising: at the host, receiving user data transmitted to the host via the network node by the UE, wherein the UE performs any of the steps of any of the Group A embodiments to transmit the user data to the host.

Embodiment 38: The method of the previous embodiment, further comprising:

Embodiment 39: The method of the previous embodiment, further comprising:

Embodiment 40: A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising:

• processing circuitry configured to provide user data; and

• a network interface configured to initiate transmission of the user data to a network node in a cellular network for transmission to a user equipment (UE), the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform any of the operations of any of the Group B embodiments to transmit the user data from the host to the UE.

Embodiment 41 : The host of the previous embodiment, wherein: • the processing circuitry of the host is configured to execute a host application that provides the user data; and

• the UE comprises processing circuitry configured to execute a client application associated with the host application to receive the transmission of user data from the host.

Embodiment 42: A method implemented in a host configured to operate in a communication system that further includes a network node and a user equipment (UE), the method comprising:

• providing user data for the UE; and

• initiating a transmission carrying the user data to the UE via a cellular network comprising the network node, wherein the network node performs any of the operations of any of the Group B embodiments to transmit the user data from the host to the UE.

Embodiment 43 : The method of the previous embodiment, further comprising, at the network node, transmitting the user data provided by the host for the UE.

Embodiment 44: The method of any of the previous 2 embodiments, wherein the user data is provided at the host by executing a host application that interacts with a client application executing on the UE, the client application being associated with the host application.

Embodiment 45: A communication system configured to provide an over-the-top service, the communication system comprising:

• a host comprising:

• processing circuitry configured to provide user data for a user equipment (UE), the user data being associated with the over-the-top service; and

• a network interface configured to initiate transmission of the user data toward a cellular network node for transmission to the UE, the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform any of the operations of any of the Group B embodiments to transmit the user data from the host to the UE.

Embodiment 46: The communication system of the previous embodiment, further comprising:

• the network node; and/or

• the user equipment.

Embodiment 47: A host configured to operate in a communication system to provide an over-the-top (OTT) service, the host comprising: • processing circuitry configured to initiate receipt of user data; and

• a network interface configured to receive the user data from a network node in a cellular network, the network node having a communication interface and processing circuitry, the processing circuitry of the network node configured to perform any of the operations of any of the Group B embodiments to receive the user data from a user equipment (UE) for the host.

Embodiment 48: The host of the previous 2 embodiments, wherein:

Embodiment 49: The host of the any of the previous 2 embodiments, wherein the initiating receipt of the user data comprises requesting the user data.

Embodiment 50: A method implemented by a host configured to operate in a communication system that further includes a network node and a user equipment (UE), the method comprising:

• at the host, initiating receipt of user data from the UE, the user data originating from a transmission which the network node has received from the UE, wherein the network node performs any of the steps of any of the Group B embodiments to receive the user data from the UE for the host.

Embodiment 51 : The method of the previous embodiment, further comprising at the network node, transmitting the received user data to the host.

Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims

1. A method performed by a candidate target relay User Equipment, UE, (502; 602), the method comprising: receiving (514; 614), from a target network node (506; 606) for a handover of a remote UE (500; 600) in association with a path switch procedure in which the candidate target relay UE (502; 602) is a candidate target relay UE for the path switch procedure, a message that enquires as to whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and sending (516; 616), to the target network node (506; 606), a response that comprises information that indicates whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE.

2. The method of claim 1 wherein a serving cell of the candidate target relay UE (502; 602) is controlled by a source network node (504; 604) for the handover and is different than a serving cell of the target relay UE (502; 604) which is controlled by the target network node (506; 606).

3. The method of claim 1 or 2 wherein the steps of receiving and sending are performed prior to triggering of the handover of the remote UE (500; 600) from the source network node (504; 604) to the target network node (506; 606).

4. The method of claim 1 or 2 wherein the steps of receiving and sending are performed after triggering of the handover of the remote UE (500; 600) from the source network node (504; 604) to the target network node (506; 606) but before the target network node (506; 606) sends an handover request acknowledgement to the source network node (504; 604).

5. A candidate target relay User Equipment, UE, (502; 602) adapted to: receive (514; 614), from a target network node (506; 606) for a handover of a remote UE (500; 600) in association with a path switch procedure in which the candidate target relay UE (502; 602) is a candidate target relay UE for the path switch procedure, a message that enquires as to whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and send (516; 616), to the target network node (506; 606), a response that comprises information that indicates whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE.

6. The candidate target relay UE (502; 602) of claim 5 further adapted to perform the method of any of claims 2 to 4.

7. A candidate target relay User Equipment, UE, (502; 602; 800) comprising: a communication interface (812) comprising a transmitter (818) and a receiver (820); and processing circuitry (802) associated with the communication interface (812), the processing circuitry (812) configured to cause the candidate target relay UE (502; 602; 800) to: receive (514; 614), from a target network node (506; 606) for a handover of a remote UE (500; 600) in association with a path switch procedure in which the candidate target relay UE (502; 602) is a candidate target relay UE for the path switch procedure, a message that enquires as to whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and send (516; 616), to the target network node (506; 606), a response that comprises information that indicates whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE.

8. The candidate target relay UE (502, 602) of claim 7 wherein the processing circuitry (812) is further configured to cause the candidate target relay UE (502; 602; 800) to perform the method of any of claims 2 to 4.

9. A method performed by a source network node (504; 604), the method comprising: selecting (510; 610) one or more candidate target relay UEs for a path switch procedure for a remote User Equipment, UE, (500; 600), the one or more candidate target relay UEs each having a serving cell that is: (a) different than a serving cell of the remote UE (500) and (b) controlled by a target network node (506; 606), the target network node (506; 606) being a network node other than the source network node (504; 604); sending (512; 612), to the target network node (506; 606), a message comprising information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (500; 600); and receiving (518; 618), from the target network node (506; 606), a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

10. The method of claim 9 further comprising: receiving (508; 608), from the remote UE (500; 600), a report comprising a list of candidate relay UEs; wherein selecting (510; 610) the one or more candidate target relay UEs for the path switch procedure for the remote UE (500; 600) comprises selecting (510; 610) the one or more candidate target relay UEs for the path switch procedure for the remote UE (500; 600) from the list of candidate relay UEs.

11. The method of claim 10 wherein the report received from the remote UE (500; 600) further comprises for each candidate relay UE in the list, information that indicates a serving cell of the candidate relay UE.

12. The method of any of claims 9 to 11 wherein: the response received from the target network node comprises information that indicates that at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE; and the method further comprises, responsive to the response comprising the information that indicates that the at least one of the one or more candidate target relay UEs acknowledge to act as a relay UE, performing one or more actions (520, 526, 528; 620-624) to complete handover of the remote UE (500; 600) to the target network node (506; 606) and a path switch for the remote UE (500; 600) such that the remote UE (500; 600) communicates with the target network node (506; 606) via a relay UE (502; 602), the relay UE (502; 602) being one of the at least one of the one or more candidate target relay UEs that acknowledge to act as a relay UE.

13. The method of any of claims 9 to 12 wherein sending (512), to the target network node (506), the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (500) comprises sending (512) the message to the target network node (506) prior to triggering a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

14. The method of claim 13 wherein receiving (518), from the target network node (506), the response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE comprises receiving (518) the response from the target network node (506) prior to triggering a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

15. The method of claim 14 wherein: the response received from the target network node comprises information that indicates that at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE; and the method further comprises, responsive to the response comprising the information that indicates that the at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE, sending (520) a handover request to the target network node (506) to initiate a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

16. The method of any of claims 9 to 12 wherein sending (612), to the target network node (606), the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (600) comprises sending (612) the message to the target network node (606) at the time of or after triggering a handover procedure for handover of the remote UE (600) from the source network node (604) to the target network node (606) but before the target network node (606) responds with a handover acknowledgment.

17. The method of claim 16 wherein the message sent to the target network node (606) is a handover request.

18. The method of claim 16 or 17 wherein receiving (618), from the target network node (606), the response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE comprises receiving (618) a handover request acknowledgment from the target network node (606), the handover request acknowledgment comprising the information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

19. The method of any of claims 16 to 18 wherein: the response received from the target network node comprises information that indicates that at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE; and the method further comprises, responsive to the response comprising the information that indicates that the at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE, performing one or more actions (620-24) for a path switch procedure for the remote UE (600) such that the remote UE (600) communicates with the target network node (606) via a relay UE (602), the relay UE (602) being one of the at least one of the one or more candidate target relay UEs that acknowledges to act as a relay UE.

20. A source network node (504; 604) adapted to: select (510; 610) one or more candidate target relay UEs for a path switch procedure for a remote User Equipment, UE, (500; 600), the one or more candidate target relay UEs each having a serving cell that is: (a) different than a serving cell of the remote UE (500) and (b) controlled by a target network node (506; 606), the target network node (506; 606) being a network node other than the source network node (504; 604); send (512; 612), to the target network node (506; 606), a message comprising information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (500; 600); and receive (518; 618), from the target network node (506; 606), a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

21. The source network node (504; 604) of claim 20 further adapted to perform the method of any of claims 10 to 19.

22. A source network node (504; 604; 900) comprising: a communication interface (906); and processing circuitry (902) associated with the communication interface (906), the processing circuitry (902) configured to cause the source network node (504; 604; 900) to: select (510; 610) one or more candidate target relay UEs for a path switch procedure for a remote User Equipment, UE, (500; 600), the one or more candidate target relay UEs each having a serving cell that is: (a) different than a serving cell of the remote UE (500) and (b) controlled by a target network node (506; 606), the target network node (506; 606) being a network node other than the source network node (504; 604); send (512; 612), to the target network node (506; 606), a message comprising information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (500; 600); and receive (518; 618), from the target network node (506; 606), a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

23. The source network node (504; 604; 900) of claim 22 wherein the processing circuitry (902) is further configured to cause the source network node (504; 604; 900) to perform the method of any of claims 10 to 19.

24. A method performed by a target network node (506; 606), the method comprising: receiving (512; 612), from a source network node (504; 604), a message comprising information that indicates one or more candidate target relay User Equipments, UEs, for a path switch procedure for a remote UE (500; 600), the one or more candidate target relay UEs each having a serving cell that is controlled by the target network node (506; 606); for each candidate target relay UE (502; 602) from the one or more candidate target relay UEs indicated in the message received from the source network node (504; 604): sending (514; 614), to the candidate target relay UE (502; 602), a message that enquires as to whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and receiving (516; 616), from the candidate target relay UE (502; 602), a response that comprises information that indicates whether the candidate target relay UE (502;

602) acknowledges to act as a relay UE; and sending (518; 618), to the source network node (504; 604), a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE, based on the response(s) received from the one or more candidate target relay UEs.

25. The method of claim 24 wherein receiving (512), from the source network node (504), the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (500) comprises receiving (512) the message from the source network node (504) prior to receiving a message that triggers a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

26. The method of claim 25 wherein sending (518), to the source network node (504), the response comprising information that indicates whether the one or more candidate target relay UEs acknowledge to act as a relay UE comprises sending (518) the response to the source network node (504) prior to receiving a message that triggers a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

27. The method of claim 25 or 26 wherein: the response sent to the source network node comprises information that indicates that at least one of the one or more candidate target relay UEs acknowledges to act as a relay UE; and the method further comprises receiving (520) a handover request from the source network node (504) to initiate a handover procedure for handover of the remote UE (500) from the source network node (504) to the target network node (506).

28. The method of claim 24 wherein receiving (612), from the source network node (604), the message comprising the information that indicates the one or more candidate target relay UEs for the path switch procedure for the remote UE (600) comprises receiving (612) the message from the source network node (604) at the time of or after triggering of a handover procedure for handover of the remote UE (600) from the source network node (604) to the target network node (606) but before the target network node (606) responds to the source network node (604) with a handover acknowledgment.

29. The method of claim 28 wherein the message received from the source network node (606) is a handover request.

30. The method of claim 28 or 29 wherein sending (618), to the source network node (604), the response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE comprises sending (618) a handover request acknowledgment to the source network node (604), the handover request acknowledgment comprising the information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE.

31. A target network node (506; 606) adapted to: receive (512; 612), from a source network node (504; 604), a message comprising information that indicates one or more candidate target relay User Equipments, UEs, for a path switch procedure for a remote UE (500; 600), the one or more candidate target relay UEs each having a serving cell that is controlled by the target network node (506; 606); for each candidate target relay UE (502; 602) from the one or more candidate target relay UEs indicated in the message received from the source network node (504; 604): send (514; 614), to the candidate target relay UE (502; 602), a message that enquires as to whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and receive (516; 616), from the candidate target relay UE (502; 602), a response that comprises information that indicates whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and send (518; 618), to the source network node (504; 604), a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE, based on the response(s) received from the one or more candidate target relay UEs.

32. The target network node (506; 606) of claim 31 further adapted to perform the method of any of claims 25 to 30.

33. A target network node (506; 606; 900) comprising: a communication interface (906); and processing circuitry (902) associated with the communication interface (906), the processing circuitry (902) configured to cause the target network node (506; 606; 900) to: receive (512; 612), from a source network node (504; 604), a message comprising information that indicates one or more candidate target relay User Equipments, UEs, for a path switch procedure for a remote UE (500; 600), the one or more candidate target relay UEs each having a serving cell that is controlled by the target network node (506; 606); for each candidate target relay UE (502; 602) from the one or more candidate target relay UEs indicated in the message received from the source network node (504; 604): send (514; 614), to the candidate target relay UE (502; 602), a message that enquires as to whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and receive (516; 616), from the candidate target relay UE (502; 602), a response that comprises information that indicates whether the candidate target relay UE (502; 602) acknowledges to act as a relay UE; and send (518; 618), to the source network node (504; 604), a response comprising information that indicates whether the one or more candidate target relay UEs acknowledges to act as a relay UE, based on the response(s) received from the one or more candidate target relay UEs.

34. The target network node (506; 606; 900) of claim 33 wherein the processing circuitry (902) is further configured to cause the target network node (506; 606; 900) to perform the method of any of claims 25 to 30.