Lossless path switching involving sidelink relays

Abstract

Responsive to triggering of inter-gNB path switching for a remote UE having an indirect connection to a gNB (56) via a relay UE, a CU-UP entity (72) of the gNB (56) receives an indication from a CU-CP entity (72) of the gNB (56). Responsive to the indication, the CU-UP entity (72) buffers packets for the remote UE.

Description

[0001] LOSSLESS PATH SWITCHING INVOLVING SIDELINK RELAYS

[0002] Technical Field

[0003] The present disclosure relates to methods for controlling operation of a wireless communication network and to corresponding devices, systems, and computer programs.

[0004] Background

[0005] In wireless communication networks, such as specified by 3GPP (3rd Generation Partnership Project), it is known to provide modes of direct wireless communication between user equipments (UEs). For example, such direct communication modes are supported for the 4G (4th Generation) LTE (Long Term Evolution) technology and for the 5G (5th Generation) NR (New Radio) technology.

[0006] Sidelink

[0007] 3GPP specified the LTE D2D (device-to-device) technology, also known as sidelink (SL) or the PC5 interface as part of Release 12 (Rel-12). The target use cases (UC) were the Proximity Services (communication and discovery). Support for such services was enhanced in Rel-13 and in Rel-14, the LTE sidelink was extensively redesigned to support vehicular communications, commonly referred to as V2X (“Vehicle-to-Anything” or V2V (Vehicle-to- Vehicle). Further enhancements were made in Release 15 (Rel-15), from the point of view of the lower radio layers. LTE SL uses broadcast communication i.e., transmission from a UE targets any receiver that is in range.

[0008] In Release 16 (Rel-16), 3GPP introduced the sidelink for the 5G NR. The driving use-case being vehicular communications with more stringent requirements than those that typically could be served by LTE SL. To meet these stringent requirements, NR SL can perform broadcast, groupcast, and unicast communications. In groupcast communication, the intended receivers of a message are typically a subset of the vehicles near the transmitter, whereas in unicast communication, there is a single intended receiver.

[0009] Both the LTE SL and the NR SL can operate with and without network coverage and with varying degrees of interaction between the UEs and the NW (network), including support for standalone, network-less operation. In 3GPP Release 17 (Rel-17), public safety was one of the most important use cases, which can benefit from the already developed NR sidelink features in Rel.16. Therefore, 3GPP specified enhancements related to public safety use cases taking the NR Rel-16 SL as the baseline. Besides, in some scenarios public safety services need to operate with partial or w / o NW coverage, such as during indoor firefighting, forest firefighting, earthquake rescue, sea rescue, etc. where the infrastructure is (partially) destroyed or not available, therefore, coverage extension is a crucial enabler for public safety, for both services communicated between UE and cellular NW and that communicated between UEs over SL.

[0010] In Rel-17, a Study Item Description (SID) on NR sidelink relay (see 3GPP document RP- 193253) was introduced which aims to further explore coverage extension for sidelink-based communication, including both UE to NW relay for cellular coverage extension and UE to UE relay for sidelink coverage extension. Now In a related Work Item Description (WID) (see 3GPP document RP-213585, 3GPP meeting RAN#94-e), only UE to NW relay was considered for Rel-17. In addition to public safety use-cases, the NR sidelink relay Wl is also designed to support other commercial use-cases which would also greatly benefit from the coverage extension. Two solutions for UE to NW relaying were specified namely Layer-2 (L2) UE-to-NW (U2N) relaying and Layer-3 (L3) U2N relaying.

[0011] As can be seen from 3GPP document R-213585, discussions were initiated in RAN#94 to identify the detailed motivations and work areas for the evolution of NR SL and NR SL relays in Rel-18. For NR SL relays, the leftover topics for service continuity of L2 relays were agreed where support for indirect-to-indirect path switch is to be introduced. In addition, the restriction in Rel-17 about service continuity being limited to intra-gNB scenarios is removed in Rel-18. In Rel-18, the support should also be introduced for the inter-gNB scenarios of path switch between direct and indirect path.

[0012] 3GPP TR 23.752 V17.0.0 (2021-03) and 3GPP TS 38.300 V17.5.0 (2023-06) further describe L2 based UE-to-Network (U2N) relaying.

[0013] Figure 1 illustrates the protocol stack for the user plane transport, related to a 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. 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 PDCP link are the Remote UE and the gNB (i.e., a base station of the NR technology). 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.

[0014] The adaptation 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.

[0015] Figure 2 illustrates the protocol stack of the NAS (Non-Access Stratum) connection for the Remote UE to the NAS-MM (NAS Mobility Management) and NAS-SM (NAS Session Management) components. The NAS messages are transparently transferred between the Remote UE and 5G-AN over the Layer 2 UE-to-Network Relay UE. The role of the UE-to- Network Relay UE is to relay the PDUs from the signaling radio bearer without any modifications.

[0016] Path Switch Procedure

[0017] Only intra-gNB path switching between indirect path and direct path is supported in Rel-17.

[0018] Figure 3 shows the intra-gNB path switching procedure from indirect path to direct path, including related RRC (Radio Resource Control) signalling:

[0019] Step 1 : Measurement configuration and reporting

[0020] Step 2: Decision of switching to a direct path by gNB

[0021] Step 3: RRC Reconfiguration message to Remote UE

[0022] Step 4: Remote UE performs Random Access to the gNB

[0023] Step 5: Remote UE feedback the RRCReconfigurationComplete to gNB via target path, using the target configuration provided in the RRC Reconfiguration message.

[0024] Step 6: RRC Reconfiguration to Relay UE

[0025] Step 7: The PC5 link is released between Remote UE and the Relay UE, if needed.

[0026] Step 8: The data path is switched.

[0027] Here, it is to be noted that the order of step 6 / 7 / 8 is not restricted.

[0028] Issues further discussed in Wl (Work Item) phase include:

[0029] - Whether Remote UE suspends data transmission via relay link after step 3;

[0030] - Whether Step 6 can be before or after step 3 and its necessity; - Whether Step 7 can be after step 3 or step 5, and its necessity / replaced by PC5 reconfiguration;

[0031] - Whether Step 8 can be after step 5.

[0032] Figure 4 shows the intra-gNB path switching procedure from direct path to indirect path:

[0033] Step 1 : Remote UE reports one or multiple candidate Relay UE(s), after Remote UE measures / discoveries the candidate Relay UE(s).

[0034] Remote UE may filter the appropriate Relay UE(s) meeting higher layer criteria when reporting, in step 1.

[0035] The reporting may include the Relay UE's ID (identity) and SL RSRP (Reference Signal Received Power) information, where the measurement on PC5 details can be left to Wl phase, in step 1 .

[0036] Step 2: Decision of switching to a target Relay UE by gNB, and target (re)configuration is sent to Relay UE optionally (like preparation).

[0037] Step 3: RRC Reconfiguration message to Remote UE. Following information may be included: 1) Identity of the target Relay UE; 2) Target Uu and PC5 configuration.

[0038] Step 4: Remote UE establishes PC5 connection with target Relay UE, if the connection has not been setup yet.

[0039] Step 5: Remote UE feedback the RRCReconfigurationComplete to gNB via target path, using the target configuration provided in RRCReconfiguration.

[0040] Step 6: The data path is switched.

[0041] Issues further discussed in the Wl phase include:

[0042] -Whether Step 2 should be after Relay UE connects to the gNB (e.g., after step 4), if not yet before;

[0043] -Whether Step 4 can be before step 2 / 3.

[0044] SDU Discard

[0045] In accordance with 3GPP TS 38.323 V17.5.0 (2023-06) discarding of SDUs (Service Data Units) on the PDCP (Packet Data Convergence Protocol) layer is organized as follows:

[0046] When a timer denoted as discardTimer expires for a PDCP SDU, or the successful delivery of a PDCP SDU is confirmed by PDCP status report, the transmitting PDCP entity shall discard the PDCP SDU along with the corresponding PDCP Data PDU. If the corresponding PDCP Data PDU has already been submitted to lower layers, the discard is indicated to lower layers. For SRBs, when upper layers request a PDCP SDU discard, the PDCP entity shall discard all stored PDCP SDUs and PDCP PDUs.

[0047] Here, it is noted that discarding a PDCP SDU already associated with a PDCP SN causes a SN gap in the transmitted PDCP Data PDUs, which increases PDCP reordering delay in the receiving PDCP entity. It is up to UE implementation how to minimize SN gap after SDU discard.

[0048] E1AP

[0049] In current 3GPP networks, a distributed architecture may be utilized for the NW nodes. For example, a gNB may be implemented on the basis of a CU (Central Unit or Centralized Unit) and one or more DUs (Distributed Units). Further, functionalities of CP (Control Plane) and UP (User Plane) may be distributed to different network nodes.

[0050] The E1 Application protocol (E1AP) as specified in 3GPP 37.483 V17.6.0 (2023-09) provides the signalling service between the gNB-CU-CP and the gNB-CU-UP of a gNB within an NG- RAN in the split architecture, or between the gNB-CU-CP and the gNB-CU-UP of an en-gNB within an E-UTRAN (Evolved UMTS Terrestrial Radio Access Network). The services provided by the E1AP are divided to UE-associated and non-UE associated.

[0051] Figure 5 shows the interface protocol structure for E1. The TNL is based on IP transport, comprising the SCTP on top of IP. The application layer signalling protocol corresponds to the E1AP.

[0052] Downlink Data Delivery Status

[0053] Downlink Data Delivery Status (DDDS) is a procedure over to convey information about the successful or unsuccessful delivery of data from the network to the UE. It is to provide feedback from the corresponding node to the node hosting the NR PDCP entity to allow the node hosting the NR PDCP entity to control the downlink (DL) user data flow via the corresponding node for the respective data radio bearer. The corresponding node may also transfer uplink (UL) user data for the concerned data radio bearer to the node hosting the NR PDCP entity together with a DL DATA DELIVERY STATUS frame within the same GTP-U PDU (GPRS Tunnelling Protocol Packet Data Unit). The DDDS procedure is also used to provide feedback from the corresponding node to the node hosting the NR PDCP entity to allow the node hosting the NR PDCP entity to control the successful delivery of DL control data to the corresponding node. Figure 6 illustrates an example of successful DDDS.

[0054] There currently exist certain challenge(s). In Rel-17, as mentioned in the above section, the support for L2 U2N relaying was introduced where the remote UE can enlist the help of a neighboring relay UE to access the network, this is called the indirect path. The aspect of service continuity was also introduced where the remote UE can continue the service it was running when switching between the direct (Uu) path and indirect path via a relay UE. The protocol stack for Rel-17 L2 U2N relaying has an end-to-end PDCP termination i.e., between the remote UE and network (gNB) and a hop-by-hop RLC (Radio Link Control) termination.

[0055] As a result, in DL transmissions, successful transmission of the packets from the gNB to the relay UE over the Uu-link does not guarantee successful transmission of the packet over the PC5-link between the relay UE and remote UE. The same is applicable to UL transmissions, where the successful transmission over the PC5-link does not guarantee successful transmission over the Uu-link. From the protocol stack, although the PDCP is E2E (end-to- end), there is no feedback mechanism at the PDCP-layer. Only the lower layers, e.g., RLC, have a feedback / retransmission mechanism. Thus, the feedback mechanism is hop-by-hop.

[0056] In a non-relaying scenario i.e., when the UE is connected to the network via the direct (Uu) link, in DL, the packet handling behaviour at the PDCP layer is that if lower layer ACK (acknowledgement) is received, then the corresponding packet is discarded. Similarly, in the UL, the packet handling behaviour is when either the discardtimer expires or a PDCP status report confirms the successful delivery of the packets or successful lower layer acknowledgement, the corresponding packets are discarded. Hence, no issues are foreseen for the non-relaying scenario. The PDCP status of the packets is based on an assigned sequence number and buffer window, which is to be aligned between the transmitter and receiver i.e., gNB and UE.

[0057] However, in a relaying scenario, as there is no E2E feedback, it is possible that packets can be discarded too early (for example, based on successful transmission over the first hop, although the packets might have failed over the second hop) or stored for a time longer than necessary (could lead to buffer overload). This is exacerbated during a path switch scenario where the path is switched from an indirect path to a direct / another indirect path. In such scenarios, misalignment in the UE and gNB PDCP status can lead to data loss and interruptions in service during the path switch procedure.

[0058] In Rel-17, this data loss was considered a corner case and since only intra-gNB scenario was supported, the PDCP status can be easily maintained when the path switch is within the same gNB. However, in Rel-18, the inter-gNB scenario should also supported and this problem of data loss is more pronounced when switching between two different gNBs.

[0059] To prevent data loss due to early discarding of the packet, the network can set a longer discardtimer or wait for the PDCP status report before discarding. However, in both of these approaches, the packet will be buffered for a timer longer than necessary, even where the E2E transmission was successful. In addition, while there exist indicators, such as the DDDS, to help the network know the status of a downlink data delivery, such indicators do not provide E2E status. Thus, although a packet transmission may be successful over the first hop, the associated DDDS does not give the network any information about the transmission over the second hop.

[0060] Accordingly, there is a need for techniques that allows for efficiently handling path-switching in U2N relaying scenarios.

[0061] Summary

[0062] Certain aspects of the disclosure and example embodiments may provide solutions to these or other challenges. One aspect is a solution for preventing data loss during a path switch scenario by preventing early discard. In addition, the solution also may help to prevent packets from being stored too long.

[0063] According to an embodiment, a method performed by a gNB operating as a network node of a wireless communications network is provided. According to the method, responsive to triggering of inter-gNB path switching for a remote UE, having an indirect connection to the gNB via a relay UE, a CU-UP entity of the gNB receives an indication from a CU-CP entity of the gNB. Responsive to the indication, the CU-UP entity buffers packets for the remote UE.

[0064] According to a further embodiment, a method performed by a gNB operating as a network node of a wireless communications network is provided. According to the method, responsive to triggering of inter-gNB path switching for a remote UE having an indirect connection to the gNB via a relay UE, a CU-CP entity of the gNB provides an indication to a CU-UP entity of the gNB. The indication causes buffering of packets for the remote UE by the CU-UP entity.

[0065] According to a further embodiment, a network node is provided. The network node is configured to perform operations of a gNB of a wireless communications network. These operations comprise, responsive to triggering of inter-gNB path switching for a remote UE having an indirect connection to the gNB via a relay UE, a CU-UP entity of the gNB receiving an indication from a CU-CP entity of the gNB. Further, these operations comprise, responsive to the indication, the CU-UP entity buffering packets for the remote UE.

[0066] According to a further embodiment, a network node is provided. The network node comprises processing circuitry and power supply circuitry configured to supply power to the processing circuitry. The processing circuitry is configured to perform operations of a gNB of a wireless communications network. These operations comprise, responsive to triggering of inter-gNB path switching for a remote UE having an indirect connection to the gNB via a relay UE, a CU- UP entity of the gNB receiving an indication from a CU-CP entity of the gNB. Further, these operations comprise, responsive to the indication, the CU-UP entity buffering packets for the remote UE.

[0067] According to a further embodiment, a network node is provided. The network node is configured to perform operations of a gNB of a wireless communications network. These operations comprise, responsive to triggering of inter-gNB path switching for a remote UE having an indirect connection to the gNB via a relay UE, a CU-CP entity of the gNB providing an indication to a CU-UP entity of the gNB. The indication causes buffering of packets for the remote UE by the CU-UP entity.

[0068] According to a further embodiment, a network node is provided. The network node comprises processing circuitry and power supply circuitry configured to supply power to the processing circuitry. The processing circuitry is configured to perform operations of a gNB of a wireless communications network. These operations comprise, responsive to triggering of inter-gNB path switching for a remote UE having an indirect connection to the gNB via a relay UE, a CU- CP entity of the gNB providing an indication to a CU-UP entity of the gNB. The indication causes buffering of packets for the remote UE by the CU-UP entity.

[0069] According to a further embodiment, a computer program or computer program product is provided, e.g., in the form of a non-transitory storage medium, which comprises program code to be executed by processing circuitry of a network node for a communication network. The program code may be stored in a memory of the network node. Execution of the program code causes the network node to perform operations of a gNB of a wireless communications network. These operations comprise, responsive to triggering of inter-gNB path switching for a remote UE having an indirect connection to the gNB via a relay UE, a CU-UP entity of the gNB receiving an indication from a CU-CP entity of the gNB. Further, these operations comprise, responsive to the indication, the CU-UP entity buffering packets for the remote UE.

[0070] According to a further embodiment, a computer program or computer program product is provided, e.g., in the form of a non-transitory storage medium, which comprises program code to be executed by processing circuitry of a network node for a communication network. The program code may be stored in a memory of the network node. Execution of the program code causes the network node to perform operations of a gNB of a wireless communications network. These operations comprise, responsive to triggering of inter-gNB path switching for a remote UE having an indirect connection to the gNB via a relay UE, a CU-CP entity of the gNB providing an indication to a CU-UP entity of the gNB. The indication causes buffering of packets for the remote UE by the CU-UP entity.

[0071] Details of such embodiments and further embodiments will be apparent from the following detailed description of embodiments.

[0072] Brief Description of the Drawings

[0073] Figure 1 shows a UP stack for L2 U2N relaying.

[0074] Figure 2 shows a CP stack for L2 U2N relaying.

[0075] Figure 3 illustrates an intra-gNB path switch procedure involving switching from an indirect connection to a direct connection of a UE.

[0076] Figure 4 illustrates an intra-gNB path switch procedure involving switching from a direct connection to an indirect connection of a UE.

[0077] Figure 5 illustrates the interface protocol structure of the E1 interface.

[0078] Figure 6 illustrates an example of a successful DDDS procedure. Figure 7 schematically illustrates an example of a U2N relaying scenario in accordance with an embodiment.

[0079] Figure 8 schematically illustrates details of a network node in accordance with an embodiment.

[0080] Figure 9 schematically illustrates details of processing circuitry of a network node in accordance with an embodiment.

[0081] Figure 10 schematically illustrates an example of a wireless communication network architecture in accordance with an embodiment.

[0082] Figure 11 schematically illustrates an example of a gNB architecture in accordance with an embodiment.

[0083] Figure 12 shows a flowchart for illustrating a method in accordance with an embodiment.

[0084] Figure 13 shows a flowchart for illustrating a method in accordance with an embodiment.

[0085] Figure 14 schematically illustrates an example of a communication system in accordance with an embodiment.

[0086] Figure 15 schematically illustrates an example of a UE in accordance with an embodiment.

[0087] Figure 16 schematically illustrates an example of a network node in accordance with an embodiment.

[0088] Figure 17 schematically illustrates an example of a host in accordance with an embodiment.

[0089] Figure 18 schematically illustrates an example of a virtualization environment in accordance with an embodiment.

[0090] Detailed Description

[0091] In the following, concepts in accordance with exemplary embodiments of the invention will be explained in more detail and with reference to the accompanying drawings. The illustrated embodiments relate to handling of path switching in U2N relaying scenarios. One or more solution embodiments introduce a new indication from the gNB-CU-CP to the gNB-CU-UP, such as may be sent over the E1 interface, to indicate the triggering of the path switch procedure for the UE. In addition, using this new indication, the gNB-CU-UP can start buffering packets at the source gNB. Then, forward all the packets to the target gNB or by exchanging the PDCP status reports, the source gNB can forward only those packets not successfully received at the UE.

[0092] Certain embodiments may provide one or more of the following technical advantage(s). The indication mentioned immediately above helps the source gNB to buffer packets only when necessary, which helps prevent buffer overload. The indication also helps to prevent early discard of the packets which would lead to data loss and cause interruptions during a path switch scenario.

[0093] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0094] The embodiments are described in the context of NR, i.e., two or more SL UEs are deployed in a same or different NR cell. However, the same principle may be applied to LTE or any other technology that enables the direct connection of two (or more) nearby devices. The embodiments are also applicable to relay scenarios including UE to network relaying and / or UE to UE relaying where the remote UE and the relay UE may be based on LTE sidelink or NR sidelink, the Uu connection between the relay UE and the base station may be LTE Uu or NR Uu. The embodiments are applicable to L2 based U2N relaying scenarios.

[0095] In the description below, the term direct link / connection refers to a link / connection between a (remote) UE and base station (gNB) over the Uu (NR / LTE) interface. The term indirect link / connection refers to a link / connection between a (remote) UE and base station (gNB) via a relay UE, i.e., the connection / link between the (remote) UE and relay UE is over the PC5 interface and that between the relay UE and base station (gNB) is over the Uu interface.

[0096] The embodiments reflect the perspectives of a (remote) UE, a relay UE, a source gNB, and a target gNB. The (remote) UE is initially under the coverage of a source gNB and subsequently performs a path switch to a target gNB.

[0097] The source / target gNB can consist of multiple cells that the (remote) UE can see. For simplicity, the description below is written such that the (remote) UE performs a handover (HO) or path switch from a cell in the source gNB to a cell in the target gNB. As a result, in the description below, the terms “cell(s)” and ”gNB(s)” are used interchangeably but no restrictions on the disclosed techniques are implied by this interchangeability of terms.

[0098] In a first embodiment, upon receiving from the remote UE a measurement report containing the measurement results for initiating a path switch procedure, the control plane (CP) of the gNB, e.g., CU-CP, sends an indication to the corresponding user plane (UP), e.g., CU-UP, about the initiation of a path switch procedure for the remote UE. The interface between the CP of the gNB or gNB-CU and UP of the gNB or gNB-CU can be over E1 , i.e., E1-interface.

[0099] In a second embodiment, which may be an extension of operations in the first embodiment, the UP of the gNB or gNB-CU, upon receiving this indication, begins buffering even those packets which have been successfully transmitted over the first hop (i.e., the Uu-link).

[0100] In a third embodiment, which may be a further extension of the above operations, the UP of the gNB or gNB-CU, upon receiving this indication, would not consider the successful acknowledgement received either from the lower layers of the UP-protocol stack or the Downlink Data Delivery Status (DDDS) to discard the packets from the buffer.

[0101] In a fourth embodiment, the UP of the gNB or gNB-CU continues to buffer the packets based on the indication from the CP of the gNB or gNB-CU until it: receives another indication from the CP of the gNB or gNB-CU -CU to stop buffering; receives an instruction to forward all the packets buffered so farto the UP of another gNB; or receives the PDCP status report from the UP of another gNB.

[0102] In a fifth embodiment, the indication from the CP of the gNB or gNB-CU includes a timer that informs the UP of the gNB for how long the packets need to be buffered.

[0103] In a sixth embodiment, the CU-UP starts a timer after it receives DDDS and decides for how long the packets need to be buffered. After the timer expires, the CU-UP discards all the buffered packets.

[0104] In a seventh embodiment, in case of an unsuccessful path switch procedure, the CP of the gNB indicates to the UP of the gNB to discard all the buffered packets. Thus, in an example scenario, a remote UE operates in a L2 based U2N relaying scenario where it has an indirect connection to a first gNB. A relay UE supports the indirect connection, with a first connection hop going between the gNB and the relay UE and with a second connection hop going between the relay UE and the remote UE. For a path switch procedure of the remote UE to a second gNB (a handover), the first gNB may be referred to as the “source” gNB and the second gNB may be referred to as the “target” gNB.

[0105] In an example embodiment of the solution(s) discussed herein, the Central Unit - Control Plane (CU-CP) of the source gNB provides an indication of the initiation of the path switch procedure to the CU User Plane (CU-UP) of the source gNB. As a particular example, the source gNB CU-CP sends a path-switch indication to the source gNB CU-UP via the E1 interface between the source gNB CU-CP and the source gNB CU-UP.

[0106] The source gNB CU-UP responds to the indication by buffering even those packets which have been successfully transmitted over the first hop (i.e., over the Uu link between the source gNB and the relay UE). Thus, the path-switch indication sent by the CU-CP to the CU-UP also may be understood as a buffering-initiation indication.

[0107] In at least one embodiment, the source gNB CU-UP modifies its normal packet discard behavior responsive to its reception of the indication. For example, it does not discard corresponding packets from its buffer despite receiving transmission ACKs or DDDS from the lower layers of its protocol stack.

[0108] In one or more embodiments, the source gNB CU-UP continues to buffer packets for the UE until it receives any one or more of: (a) a stop-buffering indication from the source gNB CU- CP; (b) an instruction to forward all packets buffered forthe UE to another gNB (e.g., the target gNB); or (c) a PDCP status report from the CU-CP of another gNB (e.g., the target gNB).

[0109] In at least one embodiment, the path-switch indication provided to the source gNB CU-UP by the source gNB CU-CP includes a timer that indicates for how long the source gNB CU-UP should buffer the packets. Here, saying that the path-switch indication includes a timer means, for example, that the indication includes a value or other data item that indicates a timer expiry period, with the CU-UP configuring and starting a timer / counter with the indicated expiry period. Alternatively, the CU-UP decides the buffering duration and configures an expiry timer accordingly. In either approach, the CU-UP discards the buffered packets upon timer expiry, with this behavior being an example of the advantageous prevention or reduction of buffer overflow issues at the CU-CP. Still further, in at least one embodiment, the source gNB CU-CP is configured to provide an indication to the source gNB CU-UP that the path switch procedure for the UE was unsuccessful, with the CU-UP being configured to discard the buffered packets responsive to this indication.

[0110] Figure 7 illustrates an example scenario where a network node 12 is communicatively coupled with a remote UE 14 via a connection 16.

[0111] The connection 16 includes a first-hop link 18 going between the network node 12 and a relay UE 20, and a second-hop link 22 going between the relay UE 20 and the remote UE 14. The remote UE 14 operates in an L2 based U2N relaying scenario with respect to the network node 12, where the network node 12 comprises, for example, an access point of a cellular network. In a particular example, the network node 12 is an eNB of a LTE network; in another example, the network node 12 is a gNB of a NR 5G network.

[0112] An example embodiment cast in the context of Figure 7 relates to a path switching scenario, where the connection path of the remote UE 14 is switched from the network node 12 as a first or source node, to another network node 24, as a second or target node. The network node 24 may be of the same type as the network node 12, or it may be of a different type. In at least one example, the network node 12 is a first or source gNB of a wireless communications network operating according to the 5G specifications promulgated by the 3GPP, and the network node 24 is a second or target gNB.

[0113] Figure 8 illustrates example details for a network node 12 or 24.

[0114] The depicted node includes processing circuitry 30, radio communications circuitry 32, and network (NW) interface circuitry 34. The processing circuitry 30 is configured to carry out overall control of the node and perform communications processing for downlink (DL) and uplink (DL) data, while the radio communications circuitry 32 includes one or more radio transmitters and receivers (radiofrequency (RF) transceiver circuitry) configured for transmitting DL data and control signals according to defined air interface protocols, and for receiving UL data and control signals according to such protocols.

[0115] The network node 12 or 24 uses the radio communications circuitry 32, for example, to provide communications service coverage in one or more cells, while it uses the network interface circuitry 34 for communicatively coupling to other nodes in the cellular network, e.g., other Radio Access Network (RAN) nodes or nodes in a Core Network (CN) of the cellular network. In this regard, the network interface circuitry 34 may comprise more than one interface, or may support multiple signaling schemes or types, and it provides wired or wireless physical-layer connectivity and any associated timing and protocol processing for anchoring network connections to other nodes.

[0116] The processing circuitry 30 comprises fixed circuitry or programmatically configured circuitry, or a mix of both. Figure 9 illustrates one example where the processing circuitry 30 comprises one or more microprocessors 40 that are specially adapted to carry output operations implementing the one or more of the solution(s) described herein, based on the execution of computer program instructions 42 held in storage 44 that is included in the microprocessor(s) 40 or otherwise connected with the microprocessor(s) 40. Here, “microprocessor” has broad meaning, and includes microcontrollers, digital signal processors, etc.

[0117] The storage 44 may further contain one or more types of data 46, such as dynamic data created and processed during live operations and / or persistent data, such as provisioning information and configuration parameters. The storage 44 comprises one or more types of computer-readable media and may include a mix of working memory for live operation and program memory for longer term storage of instructions and persistent data. Examples include any one or more DRAM, SRAM, FLASH, EEPROM, Solid State Disk (SSD), etc.

[0118] Figure 10 illustrates an example wireless communication network 50, with the network 50 diagrammed in the example context of 5G New Radio (NR). In this example, then, the network 50 includes a 5G Core Network (5GC) 52 and a Next Generation (NG) Radio Access Network (RAN) 54. The RAN 54 includes one or more gNBs 56 as examples of the network node 12 discussed above. Here, two gNBs 56-1 and 56-2 are shown by way of example, with the two gNBs 56-1 and 56-2 being configured to carry out operations described in the context of path switching for a L2 based U2N relaying scenario, as described above.

[0119] As an example, each gNB 56 includes a gNB Central Unit (gNB-CU) 60 and one or more gNB Distributed Units (gNB-DUs) 62, which are connected to the CU via a F1 interface.

[0120] The gNB-CU 60 provides overall processing and control and network interfacing, while the gNB-DUs 62 include the radio interface. The gNB-CU 60 supports an Xn-C interface for inter- gNB communications.

[0121] Figure 11 illustrates functional or logical entities within a gNB 56, where such entities are realized, for example, via underlying processing circuitry and memory. A gNB-CU-CP 70 is configured to handle Control Plane (CP) operations, while one or more instantiations of a gNB-CU-UP 72 handle User Plane (UP) operations. gNB-DUs 62 have a F1-C interface to the CU-CP 70 and have a F1-U interface with the CU-UP(s) 72. The CU-CP 70 has an E1 interface with the CU-UPs 72, which it uses in one or more example embodiments to provide the path-switching indication and related information described above, for advantageous buffering control for packets associates with a L2-relay-connected UE undergoing inter-gNB path switching.

[0122] Such operations can be understood as a gNB or other network node providing for lossless path switching in the downlink direction, for UEs that are indirectly connected to the network via sidelink relay connections. That is, the advantageous buffering prevents the loss of downlink packets for the remote UE by buffering packets for the remote UE at the source network node, including packets indicated as having been successfully transmitted on the first hop of the remote UE’s relay-based indirect connection. Moreover, by providing timer- controlled retention of these buffered packets and / or providing for other discard triggers at the source network node, the buffered packets are not indefinitely or needlessly retained at the source network node, thus decreasing buffer overflows that might otherwise arise with such retention.

[0123] Figure 12 shows a flowchart for illustrating a method, which may be utilized for implementing the illustrated concepts in a network node which performs operations of a gNB, specifically operations of a CU-UP entity of the gNB, e.g., one of the above-mentioned CU-UP entities 72. The method may be used to implement the above-mentioned functionalities applied in connection with path switching in a U2N relaying scenario.

[0124] If a processor-based implementation of the network node is used, at least some of the steps of the method of Figure 12 may be performed and / or controlled by one or more processors of the network node. Such one or more processors may implement processing circuitry of the network node. Such network node may also include a memory storing program code for implementing at least some of the below described functionalities or steps of the method of Figure 12.

[0125] At step 1210, responsive to triggering of inter-gNB path switching for a remote UE having an indirect connection to the gNB via a relay UE, the CU-UP entity of the gNB receives an indication from a CU-CP entity of the gNB, e.g., the above-mentioned CU-CP entities 70. In some scenarios, the CU-UP entity may receive the indication via an E1 interface. The inter- gNB path switching may involve a target gNB. The remote UE may correspond to the above- mentioned remote UE 14, the relay UE may correspond to the above-mentioned relay UE 20, and the gNB may correspond to the above-mentioned network node 12. The gNB may be implemented based on a distributed architecture, e.g., as explained in connection with Figures 10 and 11.

[0126] In some scenarios, the CU-UP entity may start a timer in response to receiving the indication. The indication may include a setting of the timer, e.g., a start value of the timer.

[0127] At step 1220, responsive to the indication of step 1210, the CU-UP entity buffers packets for the remote UE.

[0128] The buffering packets for the remote UE at step 1220 may involve modifying a packet discard behavior of the CU-UP entity such that the CU-UP entity does not discard packets being held in its buffer for the remote UE in response to indications of successful transmission of those packets to the relay UE. These indications of successful transmission could for example be provided via DDDS information and / or could include acknowledgements from lower protocol levels of the CU-UP entity.

[0129] In some scenarios, the buffering packets for the remote UE at step 1220 may include retaining packets for which the gNB obtained indications of successful transmission to the relay UE.

[0130] In some scenarios, the CU-UP entity may discard the packets buffered for the remote UE responsive to expiry of the timer started in response to receiving the indication.

[0131] In some scenarios, the CU-UP entity may decide the duration of buffering.

[0132] In some scenarios, the CU-UP entity may discard the packets buffered for the remote UE responsive to the earlier of the following events: expiry of the timer or occurrence of a discard trigger.

[0133] In some scenarios, the discard trigger may be one or more of: receiving a discard instruction from the CU-CP entity, or receiving a PDCP status report from the target gNB for the remote UE. In some scenarios, the CU-UP entity may discard the packets buffered for the remote UE in response to either having forwarded them to another gNB or in response to receiving a PDCP report from another gNB, e.g., from a target gNB of the path switching.

[0134] In some scenarios, the CU-UP entity may discard the packets buffered for the remote UE in response to reaching a defined time limit for said buffering.

[0135] If the inter-gNB path switching involves a target gNB, the method may continue to step 1230, which involves subsequently forwarding the packets buffered for the remote UE to the target gNB.

[0136] Figure 13 shows a flowchart for illustrating a method, which may be utilized for implementing the illustrated concepts in a network node which performs operations of a gNB, specifically operations of a CU-CP entity of the gNB, e.g., the above-mentioned CU-CP entity 70. The method may be used to implement the above-mentioned functionalities applied in connection with path switching in a U2N relaying scenario.

[0137] If a processor-based implementation of the network node is used, at least some of the steps of the method of Figure 13 may be performed and / or controlled by one or more processors of the network node. Such one or more processors may implement processing circuitry of the network node. Such network node may also include a memory storing program code for implementing at least some of the below described functionalities or steps of the method of Figure 13.

[0138] At step 1310, triggering of inter-gNB path switching occurs for a remote UE having an indirect connection to the gNB via a relay UE. The triggering of the inter-gNB path switching may be initiated by the CU-CP entity of the gNB, orthe CU-CP entity of the gNB may otherwise become aware of the triggering of the path switching.

[0139] At step 1320, responsive to the triggering of inter-gNB path switching for the remote UE, the CU-CP entity of the gNB provides an indication to a CU-UP entity of the gNB, e.g., to one or more of the above-mentioned CU-UP entities 72. The remote UE may correspond to the above-mentioned remote UE 14, the relay UE may correspond to the above-mentioned relay UE 20, and the gNB may correspond to the above-mentioned network node 12. The gNB may be implemented based on a distributed architecture, e.g., as explained in connection with Figures 10 and 11. The indication causes buffering of packets for the remote UE by the CU-UP entity. The CU- CP entity may provide the indication via an E1 interface.

[0140] The buffering of packets for the remote UE may involve modifying a packet discard behavior ofthe CU-UP entity such that the CU-UP entity does not discard packets being held in its buffer for the remote UE in response to indications of successful transmission of those packets to the relay UE. The indications of successful transmission may be provided via DDDS information or may include acknowledgements from lower protocol levels of the CU-UP entity. The buffering packets for the remote UE may include retaining packets for which the gNB obtained indications of successful transmission to the relay UE. If the inter-gNB path switching involves a target gNB, the buffering may involve or be followed by subsequently forwarding the packets buffered for the remote UE to the target gNB.

[0141] Figure 14 shows an example of a communication system 1400 in accordance with some embodiments.

[0142] In the example, the communication system 1400 includes a telecommunication network 1402 that includes an access network 1404, such as a radio access network (RAN), and a core network 1406, which includes one or more core network nodes 1408. The access network 1404 includes one or more access network nodes, such as network nodes 1410a and 1410b (one or more of which may be generally referred to as network nodes 1410), or any other similar 3rdGeneration Partnership Project (3GPP) access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 1402 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 1402 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 1402, including one or more network nodes 1410 and / or core network nodes 1408.

[0143] One or more of the network nodes 1410 may be configured as described above for a network node 12 I gNB 56. That is, one or more of the network nodes 1410 are configured to support advantageous buffering of packets for a L2-relay-connected UE undergoing inter-NW-node path switching. For example, the UE 1412A or 1412B has an indirect path / connection with the network node 1410 via a relay UE, and its path is switched over to the network node 141 OB. The network node 1410A in this example scenario performs the advantageous packet buffering.

[0144] Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU-CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., rApp), or any combination thereof (the adjective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an A1 , F1 , W1 , E1 , E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes 1410 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 1412a, 1412b, 1412c, and 1412d (one or more of which may be generally referred to as UEs 1412) to the core network 1406 over one or more wireless connections.

[0145] 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 1400 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 1400 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0146] The UEs 1412 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 1410 and other communication devices. Similarly, the network nodes 1410 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 1412 and / or with other network nodes or equipment in the telecommunication network 1402 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 1402.

[0147] In the depicted example, the core network 1406 connects the network nodes 1410 to one or more hosts, such as host 1416. 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 1406 includes one more core network nodes (e.g., core network node 1408) 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 1408. 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).

[0148] The host 1416 may be under the ownership or control of a service provider other than an operator or provider of the access network 1404 and / or the telecommunication network 1402, and may be operated by the service provider or on behalf of the service provider. The host 1416 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.

[0149] As a whole, the communication system 1400 of Figure 14 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system 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 2G, 3G, 4G, 5G standards, or any applicable future generation standard, e.g., 6G (6th Generation); 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.

[0150] In some examples, the telecommunication network 1402 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network 1402 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 1402. For example, the telecommunications network 1402 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)ZMassive loT services to yet further UEs.

[0151] In some examples, the UEs 1412 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 1404 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 1404. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

[0152] In the example, the hub 1414 communicates with the access network 1404 to facilitate indirect communication between one or more UEs (e.g., UE 1412c and / or 1412d) and network nodes (e.g., network node 1410b). In some examples, the hub 1414 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 1414 may be a broadband router enabling access to the core network 1406 for the UEs. As another example, the hub 1414 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 1410, or by executable code, script, process, or other instructions in the hub 1414. As another example, the hub 1414 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 1414 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 1414 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 1414 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 1414 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices. The hub 1414 may have a constant / persistent or intermittent connection to the network node 1410b. The hub 1414 may also allow for a different communication scheme and / or schedule between the hub 1414 and UEs (e.g., UE 1412c and / or 1412d), and between the hub 1414 and the core network 1406. In other examples, the hub 1414 is connected to the core network 1406 and / or one or more UEs via a wired connection. Moreover, the hub 1414 may be configured to connect to an M2M service provider over the access network 1404 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 1410 while still connected via the hub 1414 via a wired or wireless connection. In some embodiments, the hub 1414 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 1410b. In other embodiments, the hub 1414 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 1410b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0153] Figure 15 shows a UE 1500 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 IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, 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, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-loT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0154] A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), orvehicle-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).

[0155] The UE 1500 includes processing circuitry 1502 that is operatively coupled via a bus 1504 to an input / output interface 1506, a power source 1508, a memory 1510, a communication interface 1512, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 15. 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.

[0156] The processing circuitry 1502 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 1510. The processing circuitry 1502 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 1502 may include multiple central processing units (CPUs).

[0157] In the example, the input / output interface 1506 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 1500. 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 1508 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 1508 may further include power circuitry for delivering power from the power source 1508 itself, and / or an external power source, to the various parts of the UE 1500 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1508. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1508 to make the power suitable for the respective components of the UE 1500 to which power is supplied.

[0158] The memory 1510 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 1510 includes one or more application programs 1514, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1516. The memory 1510 may store, for use by the UE 1500, any of a variety of various operating systems or combinations of operating systems.

[0159] The memory 1510 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 random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUlCC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 1510 may allow the UE 1500 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 1510, which may be or comprise a device-readable storage medium. The processing circuitry 1502 may be configured to communicate with an access network or other network using the communication interface 1512. The communication interface 1512 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1522. The communication interface 1512 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 1518 and / or a receiver 1520 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1518 and receiver 1520 may be coupled to one or more antennas (e.g., antenna 1522) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0160] In the illustrated embodiment, communication functions of the communication interface 1512 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and / or standards, such as IEEE 802.11 , Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / internet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0161] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1512, 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).

[0162] 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.

[0163] A UE, when in the form of an Internet of Things (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 TV, 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 Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking 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 1500 shown in Figure 15.

[0164] 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 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-loT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0165] 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.

[0166] Figure 16 shows a network node 1600 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, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU). The network node 1600 may for example implement a CU-CP entity of a gNB, such as the CU-CP entity 70 of Figure 11 , or the network node 1600 may implement a CU-UP entity of a gNB, such as one of the CU-UP entities 72 of Figure 11.

[0167] Base stations 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 base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0168] 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 base station 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).

[0169] The network node 1600 includes a processing circuitry 1602, a memory 1604, a communication interface 1606, and a power source 1608. The network node 1600 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 1600 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 NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 1600 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1604 for different RATs) and some components may be reused (e.g., a same antenna 1610 may be shared by different RATs). The network node 1600 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1600, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, 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 network node 1600.

[0170] The processing circuitry 1602 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 1600 components, such as the memory 1604, to provide network node 1600 functionality.

[0171] In some embodiments, the processing circuitry 1602 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1602 includes one or more of radio frequency (RF) transceiver circuitry 1612 and baseband processing circuitry 1614. In some embodiments, the radio frequency (RF) transceiver circuitry 1612 and the baseband processing circuitry 1614 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1612 and baseband processing circuitry 1614 may be on the same chip or set of chips, boards, or units.

[0172] The memory 1604 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1602. The memory 1604 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 1602 and utilized by the network node 1600. The memory 1604 may be used to store any calculations made by the processing circuitry 1602 and / or any data received via the communication interface 1606. In some embodiments, the processing circuitry 1602 and memory 1604 is integrated.

[0173] The communication interface 1606 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 1606 comprises port(s) / terminal(s) 1616 to send and receive data, for example to and from a network over a wired connection. The communication interface 1606 also includes radio front-end circuitry 1618 that may be coupled to, or in certain embodiments a part of, the antenna 1610. Radio front-end circuitry 1618 comprises filters 1620 and amplifiers 1622. The radio front-end circuitry 1618 may be connected to an antenna 1610 and processing circuitry 1602. The radio front-end circuitry may be configured to condition signals communicated between antenna 1610 and processing circuitry 1602. The radio front-end circuitry 1618 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 1618 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1620 and / or amplifiers 1622. The radio signal may then be transmitted via the antenna 1610. Similarly, when receiving data, the antenna 1610 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1618. The digital data may be passed to the processing circuitry 1602. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0174] In certain alternative embodiments, the network node 1600 does not include separate radio front-end circuitry 1618, instead, the processing circuitry 1602 includes radio front-end circuitry and is connected to the antenna 1610. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1612 is part of the communication interface 1606. In still other embodiments, the communication interface 1606 includes one or more ports or terminals 1616, the radio front-end circuitry 1618, and the RF transceiver circuitry 1612, as part of a radio unit (not shown), and the communication interface 1606 communicates with the baseband processing circuitry 1614, which is part of a digital unit (not shown). The antenna 1610 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1610 may be coupled to the radio front-end circuitry 1618 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1610 is separate from the network node 1600 and connectable to the network node 1600 through an interface or port.

[0175] The antenna 1610, communication interface 1606, and / or the processing circuitry 1602 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna 1610, the communication interface 1606, and / or the processing circuitry 1602 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0176] The power source 1608 provides power to the various components of network node 1600 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1608 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1600 with power for performing the functionality described herein. For example, the network node 1600 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1608. As a further example, the power source 1608 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.

[0177] Embodiments of the network node 1600 may include additional components beyond those shown in Figure 16 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 1600 may include user interface equipment to allow input of information into the network node 1600 and to allow output of information from the network node 1600. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1600.

[0178] Figure 17 is a block diagram of a host 1700, which may be an embodiment of the host 1416 of Figure 14, in accordance with various aspects described herein. As used herein, the host 1700 may be or comprise various combinations 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 1700 may provide one or more services to one or more UEs.

[0179] The host 1700 includes processing circuitry 1702 that is operatively coupled via a bus 1704 to an input / output interface 1706, a network interface 1708, a power source 1710, and a memory 1712. 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 15 and 16, such that the descriptions thereof are generally applicable to the corresponding components of host 1700.

[0180] The memory 1712 may include one or more computer programs including one or more host application programs 1714 and data 1716, which may include user data, e.g., data generated by a UE for the host 1700 or data generated by the host 1700 for a UE. Embodiments of the host 1700 may utilize only a subset or all of the components shown. The host application programs 1714 may be implemented in a container-based architecture and may provide support for video codecs (e.g., Versatile Video Coding (WC), High Efficiency Video Coding (HEVC), Advanced Video Coding (AVC), MPEG, VP9) and audio codecs (e.g., FLAC, 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, heads-up display systems). The host application programs 1714 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 1700 may select and / or indicate a different host for over-the-top services for a UE. The host application programs 1714 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 (MPEG-DASH), etc.

[0181] Figure 18 is a block diagram illustrating a virtualization environment 1800 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 1800 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. In some embodiments, the virtualization environment 1800 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface.

[0182] Applications 1802 (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.

[0183] Hardware 1804 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 1806 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1808a and 1808b (one or more of which may be generally referred to as VMs 1808), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1806 may present a virtual operating platform that appears like networking hardware to the VMs 1808.

[0184] The VMs 1808 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1806. Different embodiments of the instance of a virtual appliance 1802 may be implemented on one or more of VMs 1808, 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.

[0185] In the context of NFV, a VM 1808 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 1808, and that part of hardware 1804 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, 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 1808 on top of the hardware 1804 and corresponds to the application 1802.

[0186] Hardware 1804 may be implemented in a standalone network node with generic or specific components. Hardware 1804 may implement some functions via virtualization. Alternatively, hardware 1804 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 1810, which, among others, oversees lifecycle management of applications 1802. In some embodiments, hardware 1804 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 radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1812 which may alternatively be used for communication between hardware nodes and radio units.

[0187] As can be seen, the concepts as described above may be used for efficient handling of path switch in U2N relaying scenarios. In particular, loss of data can be avoided without resorting to an E2D feedback mechanism.

[0188] It is to be understood that the examples and embodiments as explained above are merely illustrative and susceptible to various modifications. For example, the illustrated concepts may be applied in connection with various kinds of communication technologies, not necessarily limited to wireless communication. Moreover, it is to be understood that the above concepts may be implemented by using correspondingly designed software to be executed by one or more processors of an existing device or apparatus, or by using dedicated device hardware. Further, it should be noted that the illustrated apparatuses or devices may each be implemented as a single device or as a system of multiple interacting devices or modules.

[0189] 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.

[0190] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on 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 hard-wired 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.

[0191] In view of the above, examples covered by the present disclosure include, without limitation:

[0192] 1 . A method performed by a user equipment (UE), the method comprising communicating with a network node of a wireless communications network via a relay UE, where the UE operates as a remote UE having a sidelink connection to the relay UE, and where the relay UE has a connection to the network node.

[0193] 2. The method according to Example 1 , further comprising: providing user data; and forwarding the user data to a host via the transmission to the relay UE, for relaying to the network node.

[0194] Group B Examples

[0195] 3. A method performed by a network node of a wireless communications network, the method comprising: buffering packets for a remote user equipment (UE) having an indirect connection to the network node through a relay UE operating as a Layer 2 (L2) relay, responsive to triggering of a path switch procedure for the remote UE, the path switch procedure being an inter-node switchover of the remote UE from the network node as a source node to another network node as a target node.

[0196] 4. The method according to Example 3, wherein buffering the packets for the remote UE comprises buffering rather than discarding one or more packets which are indicated as having been successfully transmitted from the network node to the relay UE.

[0197] 5. A method performed by a network node of a wireless communications network, wherein the network node operates as a source node with respect to a remote user equipment (UE) that is connected to the network node via a relay UE, the method comprising: modifying a packet discard behavior of the source node with respect to packets for the remote UE, by not discarding buffered packets for the remote UE which are indicated as having been transmitted to the relay UE.

[0198] 6. A method performed by a gNB operating as a network node of a wireless communications network, the method comprising: a Central Unit - Control Plane (CU-CP) entity of the gNB providing an indication to a CU - User Plane (CU-UP) entity of the gNB, the indication provided responsive to triggering of inter-gNB path switching for a remote UE having an indirect connection to the gNB via a relay UE; and the CU-UP entity buffering packets for the remote UE, responsive to the indication.

[0199] 7. The method according to Example 6, wherein buffering packets for the remote UE includes retaining packets for the UE in a buffer of the gNB, for which the gNB obtains indications of successful transmission to the relay UE.

[0200] 8. The method according to Example 6 or 7, wherein the CU-CP entity sends the indication to the CU-UP entity via an E1 interface between the respective entities. 9. The method according to any one of Examples 6-8, wherein the inter-gNB path switching involves a target gNB, and wherein the method includes subsequently forwarding the packets buffered for the remote UE to the target gNB.

[0201] 10. The method according to any one of Examples 6-9, wherein, in response to receiving the indication, the CU-UP entity starts a timer and discards the packets buffered for the remote UE responsive to expiry of the timer.

[0202] 11. The method according to Example 10, wherein the indication provided by the CU-CP includes the timer, such that the CU-CP decides the duration of buffering.

[0203] 12. The method according to Example 10, wherein the CU-UP decides the duration of buffering.

[0204] 13. The method according to any one of Examples 10-12, wherein the CU-UP discards the packets buffered for the remote UE responsive to the earlier of expiry of the timer or occurrence of a discard trigger.

[0205] 14. The method according to Example 13, wherein the discard trigger is any one or more of: receiving a discard instruction from the CU-CP entity, or receiving a Packet Data Convergence Protocol (PDCP) status report from the target gNB for the remote UE.

[0206] 15. The method according to Example 6, further comprising the CU-UP discarding the packets buffered for the remote UE in response to either having forwarded them to another gNB, or receiving a Packet Data Convergence Protocol (PDCP) report from another gNB.

[0207] 16. The method according to Example 6, further comprising the CU-UP discarding the packets buffered for the remote UE in response to reaching a defined time limit for buffering them, the time limit decided for said buffering.

[0208] 17. The method according to Example 6, wherein buffering packets for the remote UE includes temporarily modifying a packet discard behavior of the CU-UP entity such that it does not discard packets being held in its buffer for the remote UE in response to indications of successful transmission of those packets to the relay UE. 18. The method according to Example 17, wherein the indications comprise ACKs from lower protocol levels of the CU-UP entity, or are provided via Downlink Data Delivery Status (DDDS) information.

[0209] 19. The method of any of the previous Examples 6-18, further comprising: obtaining user data; and forwarding the user data to a host or the remote UE.

[0210] Group C Examples

[0211] 20. A user equipment comprising: processing circuitry configured to perform any of the steps of any of the Group A Examples; and power supply circuitry configured to supply power to the processing circuitry.

[0212] 21. A network node comprising: processing circuitry configured to perform any of the steps of any of the Group B Examples; power supply circuitry configured to supply power to the processing circuitry.

[0213] 22. 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 Examples; 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.

[0214] 23. 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 Examples to transmit the user data from the host to the UE.

[0215] 24. The host of the previous Example, 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.

[0216] 25. 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 Examples to transmit the user data from the host to the UE.

[0217] 26. The method of the previous Example, further comprising, at the network node, transmitting the user data provided by the host for the UE.

[0218] 27. The method of any of the previous 2 Examples, 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.

[0219] 28. A communication system configured to provide an over-the-top (OTT) 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 Examples to transmit the user data from the host to the UE.

[0220] 29. The communication system of the previous Example, further comprising: the network node; and / or the UE. 30. 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 Examples to receive the user data from a user equipment (UE) for the host.

[0221] 31 . The host of the previous 2 Examples, wherein: the processing circuitry of the host is configured to execute a host application that receives 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.

[0222] 32. The host of the any of the previous 2 Examples, wherein the initiating receipt of the user data comprises requesting the user data.

[0223] 33. 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 Examples to receive the user data from the UE for the host.

[0224] 34. The method of the previous Example, further comprising at the network node, transmitting the received user data to the host.

[0225] 35. 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 operations of any of the Group A Examples to receive the user data from the host. 36. The host of the previous Example, 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.

[0226] 37. The host of the previous 2 Examples, 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.

[0227] 38. 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 Examples to receive the user data from the host.

[0228] 39. The method of the previous Example, 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 host application.

[0229] 40. The method of the previous Example, 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.

[0230] 41. 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 Examples to transmit the user data to the host. 42. The host of the previous Example, 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.

[0231] 43. The host of the previous 2 Examples, 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.

[0232] 44. 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 Examples to transmit the user data to the host.

[0233] 45. The method of the previous Example, 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.

[0234] 46. The method of the previous 2 Examples, 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.

Claims

Claims1. A method performed by a gNB (12; 56-1 , 56-2; 56) of a wireless communications network, the method comprising: responsive to triggering of inter-gNB path switching for a remote user equipment, UE, (14) having an indirect connection to the gNB (12; 56-1 , 56-2; 56) via a relay UE (20), a Central- Unit - User Plane, CU-UP, entity (72) of the gNB (12; 56-1 , 56-2; 56) receiving an indication from a Central Unit - Control Plane, CU-CP, entity (70) of the gNB (12; 56-1 , 56-2; 56); and responsive to the indication, the CU-UP entity (72) buffering packets for the remote UE (14).

2. The method according to claim 1 , wherein said buffering packets for the remote UE (14) comprises modifying a packet discard behavior of the CU-UP entity (72) such that the CU- UP entity (72) does not discard packets being held in its buffer for the remote UE (14) in response to indications of successful transmission of those packets to the relay UE (20).

3. The method according to claim 2, wherein the indications of successful transmission are provided via Downlink Data Delivery Status, DDDS, information.

4. The method according to claim 2 or 3, wherein the indications of successful transmission comprise acknowledgements from lower protocol levels of the CU-UP entity (72).

5. The method according to any of the preceding claims, wherein said buffering packets for the remote UE (14) includes retaining packets for which the gNB (12; 56-1 , 56-2; 56) obtained indications of successful transmission to the relay UE (20).

6. The method according to any of the preceding claims, wherein the CU-UP entity (72) receives the indication via an E1 interface.

7. The method according to any of the preceding claims, wherein the inter-gNB path switching involves a target gNB (24), and wherein the method includes subsequently forwarding the packets buffered for the remote UE (14) to the target gNB (24).

8. The method according to any of the preceding claims, wherein, in response to receiving the indication, the CU-UP entity (72) starts a timer and discards the packets buffered for the remote UE (14) responsive to expiry of the timer.

9. The method according to claim 8, wherein the indication includes a setting of the timer.

10. The method according to claim 8 or 9, wherein the CU-UP entity (72) discards the packets buffered for the remote UE (14) responsive to the earlier of: expiry of the timer or occurrence of a discard trigger.

11. The method according to claim 10, wherein the discard trigger is one or more of: receiving a discard instruction from the CU-CP entity, or receiving a Packet Data Convergence Protocol, PDCP, status report from the target gNB (24) for the remote UE (14).

12. The method according to any of the preceding claims, wherein the CU-UP entity (72) decides the duration of buffering.

13. The method according to any of the preceding claims, further comprising the CU-UP entity (72) discarding the packets buffered for the remote UE (14) in response to either having forwarded them to another gNB (24), or receiving a PDCP report from another gNB (24).

14. The method according to any of the preceding claims, further comprising the CU-UP entity (72) discarding the packets buffered for the remote UE (14) in response to reaching a defined time limit for said buffering.

15. A method performed by a gNB (12; 56-1 , 56-2; 56) of a wireless communications network, the method comprising: responsive to triggering of inter-gNB path switching for a remote user equipment, UE, (14) having an indirect connection to the gNB (12; 56-1 , 56-2; 56) via a relay UE (20), a Central Unit - Control Plane, CU-CP, entity (70) of the gNB (12; 56-1 , 56-2; 56) providing an indication to a Central Unit - User Plane, CU-UP, entity (72) of the gNB (12; 56-1 , 56-2; 56), wherein the indication causes buffering of packets for the remote UE by the CU-UP entity.

16. The method according to claim 15, wherein said buffering packets for the remote UE (14) comprises modifying a packet discard behavior of the CU-UP entity (72) such that the CU- UP entity (72) does not discard packets being held in its buffer for the remote UE (14) in response to indications of successful transmission of those packets to the relay UE (20).

17. The method according to claim 16, wherein the indications of successful transmission are provided via Downlink Data Delivery Status, DDDS, information.

18. The method according to claim 16 or 17, wherein the indications of successful transmission comprise acknowledgements from lower protocol levels of the CU-UP entity (72).

19. The method according to any of claims 15 to 18, wherein said buffering packets for the remote UE (14) includes retaining packets for which the gNB (12; 56-1 , 56-2; 56) obtained indications of successful transmission to the relay UE (14).

20. The method according to any of claims 15 to 19, wherein the CU-CP entity (70) provides the indication via an E1 interface.21 . The method according to any of claims 15 to 20, wherein the inter-gNB path switching involves a target gNB (24), and said buffering comprises subsequently forwarding the packets buffered for the remote UE (14) to the target gNB (24).

22. A network node (1410A, 1410B; 1600), the network node (1410A, 1410B; 1600) being configured to perform operations of a gNB (12; 56-1 , 56-2; 56) of a wireless communications network, said operations comprising: responsive to triggering of inter-gNB path switching for a remote user equipment, UE, (14) having an indirect connection to the gNB (12; 56-1 , 56-2; 56) via a relay UE (20), a Central Unit - User Plane, CU-UP, entity (72) of the gNB (12; 56-1 , 56-2; 56) receiving an indication from a Central Unit - Control Plane, CU-CP, entity (70) of the gNB (12; 56-1 , 56-2; 56); and responsive to the indication, the CU-UP entity (72) buffering packets for the remote UE (14).

23. The network node (1410A, 1410B; 1600) of claim 22, further configured to perform operations according to the method of any of claims 2 to 14.

24. The network node (1410A, 1410B; 1600) according to claim 22 or 23, comprising: processing circuitry (30; 1602) configured to perform the method of any of claims 1 to 14; and power supply circuitry (1608) configured to supply power to the processing circuitry (30; 1602).

25. A network node (1410A, 1410B; 1600), the network node (1410A, 1410B; 1600) being configured to perform operations of a gNB (12; 56-1 , 56-2; 56) of a wireless communications network, said operations comprising: responsive to triggering of inter-gNB path switching for a remote user equipment, UE, (14) having an indirect connection to the gNB (12; 56-1 , 56-2; 56) via a relay UE (20), a Central Unit - Control Plane, CU-CP, entity (70) of the gNB (12; 56-1 , 56-2; 56) providing an indication to a Central Unit - User Plane, CU-UP, entity (72) of the gNB (12; 56-1 , 56-2; 56),wherein the indication causes buffering of packets for the remote UE (14) by the CU-UP entity (72).

26. The network node (1410A, 141 OB; 1600) of claim 25, further configured to perform operations according to the method of any of claims 16 to 21 .

27. The network node (1410A, 141 OB; 1600) according to claim 25 or 26, comprising: processing circuitry (30; 1602) configured to perform the method of any of claims 15 to 21 ; and power supply circuitry (1608) configured to supply power to the processing circuitry (30; 1602).

28. A computer program or computer program product comprising program code to be executed by processing circuitry of a network node for a communication network, wherein execution of the program code by the processing circuitry causes the network node to perform a method according to any of claims 1 to 14.

29. A computer program or computer program product comprising program code to be executed by processing circuitry of a network node for a communication network, wherein execution of the program code by the processing circuitry causes the network node to perform a method according to any of claims 15 to 21 .

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