Method and communication device

Abstract

This method includes determining that the link quality of an indirect communication link can no longer support the communication of a data unit, and transmitting, via a direct communication link, a indication that the indirect communication link can no longer support the communication of the data unit and a status report of the transmission or reception of a data unit for recovering any of the lost data units, or determining that the link quality of a direct communication link can no longer support the communication of a data unit, and transmitting, via an indirect communication link, an indication that the direct communication link cannot support the communication of the data unit and a status report of the transmission or reception of a data unit for recovering any of the lost data units.

Description

Technical Field

[0001] The present disclosure relates to a method and a communication device (user equipment or radio transceiver unit) configured to transmit or receive using multi-path communication including a direct communication link with infrastructure equipment and an indirect communication link with a relay device via a sidelink communication link. The present disclosure claims the Paris Convention priority of European Patent Application EP22184827.8 filed on July 13, 2022, the content of which is incorporated herein by reference in its entirety.

Background Art

[0002] The "Background" description provided herein is for the purpose of generally presenting the context of the present disclosure. The achievements of the currently named inventors within the scope described in this background section, and aspects of this specification that may not be eligible as prior art at the time of filing, are not admitted as prior art to the present invention, either expressly or implicitly.

[0003] Wireless communication networks currently support communication with a wider range of communication devices and user equipment for various application and data traffic profiles and types. For example, communication is currently supported by devices including devices with reduced complexity, machine type communication (MTC) devices, high-resolution video displays, virtual reality headsets, etc. Among these different types of devices, some are deployed in very large quantities, such as devices with reduced complexity for supporting the "Internet of Things", and are typically associated with relatively high latency tolerance and relatively small amounts of data transmission. Other types of devices, such as devices supporting high-resolution video streaming, may be associated with relatively low latency tolerance and relatively large amounts of data transmission.

[0004] To provide coverage for increasing devices such as IoT, 5G radio access technology (RAT), also known as new radio (NR) system, includes aspects and functions designed to support connections in a wide range of environments. For example, in order to improve the coverage of communication devices (such as user equipment), a technology that utilizes an ad-hoc relay device formed by other communication devices may be adopted. The radio access interface to the relay device is called a sidelink. In an example of 3GPP (registered trademark), the sidelink interface is called the PC5 interface, and the direct communication interface with the infrastructure equipment of the wireless communication network is called the Uu interface. Utilizing both direct communication links and indirect communication links may cause technical problems. Summary of the Invention Means for Solving the Problems

[0005] This disclosure may help to address or mitigate at least some of the problems described above.

[0006] Embodiments of the present technology are methods performed by a communication device for transmitting data to, or receiving data from, a wireless communication network, the method comprising establishing multi-path communication with wireless network infrastructure equipment of the wireless communication network, the multi-path communication comprising a first direct communication link with the wireless network infrastructure equipment and an indirect communication link via a relay communication device comprising a sidelink communication link with the relay communication device providing a second direct communication link with the wireless network infrastructure equipment; transmitting a data unit to the wireless network infrastructure equipment using the multi-path communication, or receiving a data unit from the wireless network infrastructure equipment using the multi-path communication. The direct communication link with the infrastructure equipment may be a Uu interface, and the sidelink communication link with the relay may use a PC5 interface. The method comprises determining that the link quality of the indirect communication link can no longer support communication of the data unit; transmitting, via the direct communication link, an indication that the indirect communication link can no longer support communication of the data unit and a status report of transmission or reception of a data unit for recovering any of the lost data units; or determining that the link quality of the direct communication link can no longer support communication of the data unit; transmitting, via the indirect communication link, an indication that the direct communication link can no longer support communication of the data unit and a status report of transmission or reception of a data unit for recovering any of the lost data units.

[0007] Exemplary embodiments can provide efficient recovery of multi - path communication between a communication device and infrastructure equipment, which detects when one of a direct communication link via the Uu interface to the infrastructure equipment (gNB), or a side - link, or an indirect communication link using a relay via the PC5 interface stops supporting communication of data units, transmits an indication via the other of the direct or indirect communication links that are not impaired, and transmits an indication of the data units that have been successfully communicated or the last data unit to be communicated, so that the network can identify the data units lost as a result of a failure of the direct or indirect communication link. In one example, the data unit is a packet data unit (PDU) of the packet data convergence protocol (PDCP).

[0008] Another aspect of the exemplary embodiments also relates to a technique for recovering data units when one or more of the indirect and direct communication links of multi - path communication fail, in which case the cell formed by the infrastructure equipment providing the direct communication link and the cell ID of the relay are communicated as part of the re - establishment procedure.

[0009] Each aspect and feature of the present disclosure is defined in the appended claims and includes a communication device (UE), infrastructure equipment, and a method for operating them.

[0010] It should be understood that both the foregoing general description and the following detailed description are exemplary and not restrictive. The described embodiments will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings, which will be described hereinafter, together with further advantages.

[0011] A more complete understanding of the present disclosure and its attendant advantages will be more readily obtained as the following detailed description is considered in connection with the accompanying drawings, in which like reference numerals designate the same or corresponding parts throughout the several views.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0013] New radio access technology (5G) FIG. 1 shows a configuration example of a wireless communication network using some of the terms proposed and used in NR and 5G. In FIG. 1, a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 41, 42 by a connection interface represented as line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a radio access interface within the radio frequency bandwidth available in the wireless communication network. Thus, within the range for performing wireless communication via the radio access interface, each of the TRPs 10 forms a cell of the wireless communication network as represented by circle 12. In this way, a wireless communication device 14 within the wireless communication range provided by cell 12 can transmit and receive signals to and from the TRP 10 via the radio access interface. Each of the distributed units 41, 42 is connected to a central unit (CU) 40 (which may also be called a control node) via an interface 46. And the central unit 40 is connected to a core network 20 that may include all other functions necessary for data transmission for communicating with the wireless communication device, and the core network 20 may be connected to another network 30.

[0014] As will be understood by those skilled in a wireless communication network compliant with the 5G standard as shown in FIG. 1, CU40, DU42, and TRP10 collectively refer to the functions conventionally performed by a network base station, or a gNodeB (gNB) according to 5G terminology. In terms of broad top-level functionality, the term network infrastructure device / access node may be used to encompass these elements and the elements of a conventional base station type of a wireless communication system. Depending on the application at hand, the scheduling responsibility for transmissions scheduled on the radio interface between each DU and the communication device may lie with the control node / central unit and / or the distributed unit / TRP.

[0015] FIG. 1 shows a communication device 14 within the coverage area of a first communication cell 12. This communication device 14 may thus exchange signals with a first CU40 within the first communication cell 12 via one of the distributed units / TRPs 10 associated with the first communication cell 12. The communication device 14 may be referred to as a mobile terminal, terminal, or user equipment (UE) that includes a chipset and has functions corresponding to a UE device known for operation in a wireless communication network.

[0016] As shown above, the exemplary embodiments can provide arrangements for improving reliability and communication quality for examples where a remote UE is transmitting or receiving data directly with a wireless communication network, i.e., for example, an example where data is being transmitted and / or received between a gNodeB, such as the TRP of FIG. 1, and a wireless infrastructure device, and an example where data is being transmitted and / or received indirectly via a relay UE. The relay UE operates to receive data from the remote UE, transmit data to the remote UE, transmit that data to a gNB within the wireless communication network, or receive data from the gNB. Thus, the exemplary embodiments relate to a multi-path scenario where a remote UE directly uses a communication path with the wireless communication network and indirectly uses a communication path with the wireless communication network via a relay UE.

[0017] It has already been considered that service continuity can be enhanced for network relaying from a single-hop layer to a UE by switching between direct communication and indirect communication. For example, the following scenarios are assumed.

[0018] A. Inter-gNB indirect-direct path switching, i.e., switching from UE1 <-> Relay UEA <-> gNBX to UE1 <-> gNBY; B. Inter-gNB direct-indirect path switching, i.e., switching from UE1 <-> gNBX to UE1 <-> Relay UEA <-> gNBY; C. Intra-gNB indirect-indirect path switching, i.e., switching from UE1 <-> Relay UEA <-> gNBX to UE1 <-> Relay UEB <-> gNBX; D. Inter-gNB indirect-indirect path switching, i.e., switching from UE1 <-> Relay UEA <-> gNBX to UE1 <-> Relay UEB <-> gNBY;

[0019] In addition, to enhance reliability in different scenarios and overall, multi-path communication may exist where Layer 2 and Layer 3 communications are provided via both direct and indirect paths. That is, in a multi-path scenario, a remote UE is connected to a gNB via a direct link and an indirect link, and the indirect link is connected to a radio communication network via a relay UE. According to multi-path communication, a UE can simultaneously activate both the Uu link and the PC5 link and split / integrate user traffic at the PDCP layer (Uu PDCP) between the gNB and the UE. The advantage of this approach is that Uu PDCP security between the gNB and the UE can be used even for traffic passing through a network relay from the UE. Therefore, user data for downlink communication can be encrypted by a PDCP entity in the gNB-CU, and traffic can be switched between the Uu link and another link via a relay UE. Both the link between the remote UE and the relay UE are Uu links and are transmitted on the radio link control, RLC channel. That is, data is split between direct communication and indirect communication. An example of multi-path communication is shown in FIG. 2.

[0020] As shown in FIG. 2, the remote UE 200 communicates data via a radio communication network in which the gNB 100 forms part of the radio network infrastructure equipment of the radio communication network and is connected to the core network 400. As shown in FIG. 2, the remote UE 200 communicates data using the PDCP protocol layers 201a, 201b via a data link with the gNB 100. The PDCP layers 201a, 201b form part of the protocol stack 202 represented as two protocol stacks 102a, 102b for the direct communication link 102a and the indirect communication link 102b, and as tables on the remote UE 200 and the gNB 100. The remote UE 200 can perform data communication with the gNB 100 using the PDCP layers 201a, 201b via the direct communication link 250 with the gNB 100 and the indirect communication links 350, 450 via the relay UE 300. The communication link 350 with the relay UE 300 is formed from the PC5 interface. Thus, the protocol stack 202 is within the remote UE 200 and includes the radio link control layer SL-RLC, the media access layer SL-MAC, and the physical layer SL-PHY for the sidelink. Through these, data from the PDCP is communicated to the relay UE via the sidelink 350 and then communicated to the gNB 100 via the second direct communication link 450 from the relay UE 300. As shown for the protocol stack 202 within the remote UE 200, the PDCP data is also communicated via the direct communication link 250 formed from the Uu interface using the radio link control layer RLC, the media access layer MAC, the physical layer PHY within the protocol stack 102a of the gNB 100, and the corresponding layers. Thus, according to the arrangement shown in FIG. 2, the PDCP data is communicated as protocol data units (PDUs) transmitted or received between the gNB 100 using the protocol stacks 202, 102a, 102b in accordance with the currently proposed technology. That is, according to the arrangement shown in FIG. 2, the relay UE 300 maps the remote UE traffic received from the gNB to the sidelink 350. The remote UE 200 has PDCP PDUs received from both the Uu and SL interfaces.The PDCP entity of the UE combines traffic at the PDCP layer 201a. Further, between the relay UE and the remote UE, there are SL-SDAP and SL-PDCP entities, which are not shown here for simplicity. Similarly, in the uplink direction, the remote UE PDCP entity splits the traffic and transmits this as PDCP PDUs directly via 250 and indirectly via communication paths 350, 450, and receives them at the gNB directly or via the relay UE 300. The splitting of traffic is one example, and redundant traffic is another example. The splitting of traffic in the downlink can be a network decision. For uplink traffic splitting, the network must set rules for the UE to split the data, e.g., a splitting ratio of 50:50 or 60:40 based on traffic volume and / or radio conditions. However, embodiments of the present technology are useful for addressing the problem of radio link failures where multi-path communication of PDCP data is repeated on the indirect communication paths 350, 450 or switched between the indirect communication paths 350, 450 and the direct communication path 250. This will be described in the following paragraphs.

[0021] Radio link failure When a remote UE is providing a service supported by a multi-path communication link, there are technical problems in dealing with situations where a failure occurs in one or both of the direct (Uu) and indirect (PC5) communication links of the multi-path communication. In the scenario of multi-path communication, when a failure occurs in both the link Uu and the SL, the UE can declare a radio link failure (RLF). When a failure occurs in one of the links, it is necessary to enable reporting of the RLF from the remaining link, which in principle has the same behavior as the RLF reporting in the case of being configured with dual connectivity. Some possible scenarios are shown in FIGS. 3A, 3B, and 3C, which are labeled with the same numbers as the parts shown in FIG. 2. As shown in FIG. 3A, the remote UE 200 is served by multi-path communication including a direct communication link 250 and an indirect communication path via a relay UE using communication links 350 and 450 corresponding to the arrangement shown in FIG. 2. As shown in FIG. 3A, the black cross mark 460 indicates that a failure has occurred in the Uu communication link between the relay UE 300 and the gNB 100, and as shown in FIG. 3B, the black cross mark 360 indicates that a failure has occurred in the sidelink communication link 350 between the remote UE 200 and the relay 300. Finally, in FIG. 3C, the occurrence of a failure in the direct communication link 250 between the remote UE 200 and the gNB 100 is indicated by the black cross mark 260.

[0022] In a scenario where a UE can switch between a direct communication path and an indirect communication path, radio link failure (RLF) in the side link and operation when a failure occurs in the direct communication path on the Uu interface are considered in TS38.300. This disclosure, together with TS38.331, provides for the re-establishment procedure initiation of the indirect communication link via the PC5 interface, the direct communication link via the Uu interface, and radio resource control operations for radio beam failure or physical layer failure. Operations during handover where the UE can provide a configured side link that permits handover are also considered. The scenario of this disclosure defines a process based on the assumption that the UE can perform side link communication in RRC connected mode and report a failure on the side link using the Uu link. This procedure can be used when the Uu is configured with multi-path communication. However, there remain technical problems regarding the general handling of radio link failure (RLF) in multi-path communication, and more specifically, handling and reporting RLF in the direct communication link with radio network infrastructure equipment via the Uu interface using an indirect communication path with infrastructure equipment using a relay node via the PC5 interface. In other embodiments, the technical problem relates to the handling of side link (SL) RLF, i.e., a failure on the SL via the PC5 interface on an indirect communication path with radio network infrastructure equipment via a relay device. In some exemplary embodiments, the UE may have two or more SLs for two or more relay devices to communicate on an indirect communication path to radio network infrastructure equipment, and the RLF may occur on one of those SLs for one of those relay devices. In response, the UE may transmit a message via the direct communication link of the multi-path communication link via the Uu interface to identify which relay device and which SL communication link the RLF occurred on. This may include an indication of which SL survived, although it may be implicit since the remaining links survived.

[0023] In other exemplary embodiments, the UE may establish a multi-path communication link, and since a direct communication path is established using a plurality of carriers, i.e., a Uu interface with carrier aggregation or dual connectivity, communication can continue even if a failure occurs in communication on one carrier, and RLF can be reported via any of the surviving carriers or the surviving SLs.

[0024] Embodiments of the present technology can provide a method executed by a communication device for transmitting data to a wireless communication network or receiving data from a wireless communication network. This method includes establishing multi-path communication with a wireless network infrastructure device of a wireless communication network, including a first direct communication link with a wireless network infrastructure device and an indirect communication link via a relay communication device including a sidelink communication link with a relay communication device that provides a second direct communication link with the wireless network infrastructure device, and transmitting a data unit to the wireless network infrastructure device using the multi-path communication, or receiving a data unit from the wireless network infrastructure device using the multi-path communication. The method includes determining that the link quality of the direct communication link cannot support communication of the data unit, determining that the direct communication link cannot support communication of the data unit, and transmitting a status report of transmission or reception of the data unit for recovering the lost data unit via the indirect communication link.

[0025] According to another exemplary embodiment, after establishing a multi-path communication link, the communication device determines that the link quality of the indirect communication link can no longer support the communication of data units by transmitting data units to the radio network infrastructure device or receiving data units from the radio network infrastructure device via the sidelink communication link, and indicates via the direct communication link that the indirect communication link can no longer support the communication of data units, along with an indication that the indirect communication path has been released and a status report of the transmission or reception of data units used to recover any of the lost data units. This indication is transmitted, for example, as a Uu message.

[0026] Embodiments provide techniques for addressing the following examples. 1. When RLF occurs on both the direct communication link and the indirect communication link and the UE attempts to perform RRC reestablishment, it may take a long time for the reestablishment. Therefore, the UE may be able to discover the sidelink relay UE before the reestablishment procedure succeeds. If the discovery of the sidelink is successful and the PC5 interface can be established, the RLF can be reported via the SL including the new relay or the old relay. 2. When RLF occurs on the SL / PC-5 interface, the PC-5 RRC connection is released and reported to the gNB using the SL information via a Uu message, and involves procedures for managing data loss including, for example, a new PDCP status report included in the SL information Uu message or the last successfully received PDCP serial number SN.

[0027] A more detailed view of the components shown in FIGS. 1 and 2 is provided in FIG. 4. In FIG. 4, a TRP 120 that approximately corresponds to the TRP 10 in FIG. 1, as a simplified representation, includes a transmitter 126, a receiver 124, and a controller or control processor 122 that controls the transmitter 126 and the receiver 124 to transmit and receive radio signals to and from one or more UEs within a cell (not shown in FIG. 3 for clarity) provided by the TRP 120.

[0028] As shown in FIG. 4, the TRP 120 is connected to the DU 140 via a physical interface 130 that may be, for example, an optical fiber cable. Accordingly, the physical interface 130 provides a communication link for data and signaling traffic from the TRP 210 to the core network 400 via the DU 140 and the CU 160. The interface 150 between the DU 140 and the CU 160 is known as the F1 interface, which can be a physical or logical interface. The F1 interface 150 between the DU 140 and the CU 160 operates according to the specifications 3GPP TS 38.470 and 3GPP TS 38.473 and may be formed from an optical fiber or other wired or wireless high-bandwidth connection. The connection between the TRP 210 and the core network 400 can generally be referred to as a backhaul and includes the physical interface 130 from the TRP 120 to the DU 140 and the F1 interface 150 from the DU 140 to the CU 160.

[0029] As shown in FIG. 2, TRP120 may be configured to transmit a downlink radio signal and receive an uplink radio signal from the remote UE200 via a direct radio communication link 250 from the remote UE200 to the remote UE200. The direct radio communication link 250 may be, in one example, a Uu interface. The remote UE200 includes a transmitter 226, a receiver 224, and a controller 222 configured to control the transmitter 226 and the receiver 224 to transmit an uplink signal to the TRP120 via the radio communication link 250 formed between the remote UE200 and the TRP120 and receive a downlink signal from the TRP120. When the remote UE200 communicates with the TRP120 / gNB100 via the direct radio communication link 250 between the remote UE200 and the TRP120 / gNB100, it can be said that the remote UE200 communicates with the TRP120 / gNB100 via a "direct path". The direct radio communication link of a communication device (such as a UE) is interpreted as a radio communication link to the infrastructure device (such as a gNB) of a radio communication network that does not pass through an intermediate radio communication link (such as a sidelink radio communication link).

[0030] As shown in FIG. 4, TRP120 may be configured to transmit a downlink radio signal via a direct radio communication link 450 and receive an uplink radio signal from the relay UE200. The direct radio communication link 450 may be, in one example, a Uu interface. The relay UE300 includes a transmitter 326, a receiver 324, and a controller 322 configured to control the transmitter 326 and the receiver 324 to transmit an uplink signal to the TRP120 via the direct radio communication link 450 formed between the relay UE300 and the TRP120 and receive a downlink signal from the TRP120.

[0031] As shown in FIG. 4, the controller 322 of the relay UE 300 may be configured to control the transmitter 326 to transmit a downlink signal to the remote UE 200 via the sidelink wireless communication link 350, and control the receiver 324 to receive an uplink signal from the remote UE 200 via the sidelink wireless communication link 350. Similarly, the controller of the remote UE 200 may be configured to control the receiver 224 to receive a downlink signal from the relay UE 300, and control the transmitter 226 to transmit an uplink signal to the relay UE 300. The sidelink wireless communication link 350 between the relay UE 300 and the remote UE 200 is a sidelink wireless communication link such as a PC-5 interface. Therefore, the relay UE 300 may be configured to relay signals between the remote UE 200 and the TRP 120. When the remote UE 200 communicates with the TRP 120 / gNB 100 via the relay UE 300 (i.e., via the sidelink wireless communication link 350 between the remote UE 200 and the relay UE 300 and the direct wireless communication link 450 between the relay UE 300 and the TRP 120 / gNB 100), it can be said that the remote UE 200 communicates with the gNB 100 via an "indirect path". Although not shown in FIG. 4, the indirect path may further include one or more additional relay UEs.

[0032] In the example shown in FIG. 4, since the relay UE 300 relays signals between the remote UE 200 and the infrastructure device of the wireless communication network (i.e., the gNB 100), the relay UE 300 may be referred to as "UE-network (U2N)" relay. As will be understood by those skilled in the art, one or more other relay UEs may relay signals between the remote UE 200 and the relay UE 300 along the indirect path to the gNB 100, thereby functioning as "UE-UE (U2U)" relay.

[0033] Transmitters 126, 226, 326 and receivers 124, 224, 324 (and other transmitters, receivers and transceivers described in connection with the examples and embodiments of the present disclosure) may include, for example, radio frequency filters and amplifiers as well as signal processing components and devices for transmitting and receiving wireless signals according to, for example, the 5G / NR standard. Controllers 122, 222, 322 (and other controllers described in connection with the examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU, or an application-specific chipset, etc., and are configured to execute instructions stored in a computer-readable medium such as non-volatile memory. The processing steps described herein can be executed, for example, by a microprocessor in conjunction with a random access memory operating according to instructions stored in a computer-readable medium. Transmitters, receivers, and controllers are schematically shown as separate elements in FIG. 3 for ease of representation. However, it will be understood that the functions of these elements can be provided in a variety of different ways, such as using, for example, one or more appropriately programmed programmable computers or one or more appropriately configured application-specific integrated circuits / circuits / chips / chip sets.

[0034] As shown in FIG. 4, the TRP 120, the DU 140, and the CU 160 may collectively form a gNB 100, which is an example of infrastructure equipment of a wireless communication network. Accordingly, references to the remote UE 200 or the relay UE 300 communicating with the TRP 120 can alternatively be considered as references to the remote UE 200 or the relay UE 300 communicating with the gNB 100. Furthermore, it will be understood that the remote UE 200 and the relay UE 300 are examples of communication devices. As will be appreciated, infrastructure equipment / TRP / base station / gNB, like the UE / communication device, is generally composed of various other elements related to its operating functions.

[0035] Therefore, as described above, the remote UE 200 can communicate with the gNB 100 either directly (i.e., via the direct wireless communication link 250 between the remote UE 200 and the gNB 100) or indirectly (i.e., via the sidelink wireless communication link 350 between the remote UE 200 and the relay UE 300 and the direct wireless communication link 450 between the relay UE 300 and the gNB 100). Conventionally, the remote UE 200 is configured to communicate via either the direct path or the indirect path at any given time, but cannot communicate via both simultaneously. For example, when the remote UE 200 is within the cell provided by the gNB 100, the remote UE 200 may be configured to communicate via the direct path. Alternatively, when the remote UE 200 is outside the cell provided by the TRP 120 but the relay UE 300 is within the cell provided by the TRP 120, the remote UE 200 may be configured to communicate via the indirect path. Thus, the relay UE 300 can provide coverage for the remote UE 200.

[0036] Uu Link Failure and Reporting to gNB via Relay UE According to an exemplary embodiment, when the UE detects that a failure has occurred in the Uu link or the Uu link quality has fallen below a threshold, the UE notifies the relay UE that the Uu link can no longer support communication via the direct communication link. This example is shown in FIG. 5. As shown during the first stage of FIG. 5, the remote UE 200 is supported by multi-path communication using a direct communication link via the Uu interface with the gNB 100 and an indirect communication path via the remote UE 300 that uses the side link (SL) PC5 interface with the relay UE 300 that has established a communication link with the gNB 100 via the Uu interface. As shown, in the initial stage 500, the remote UE receives downlink data in the form of PDUs from the gNB 100 and transmits the uplink data as PDUs to the gNB 100 via multi-path communication via the direct link (via the Uu interface) and the indirect communication link via the relay UE 300 (via the PC5 interface). However, at a certain point 502, since the link quality of the Uu interface with the gNB 100 has fallen below a predetermined threshold, the Uu interface can no longer be used for the direct communication link with the gNB 100.

[0037] To determine that the communication link with gNB100 via the Uu interface is below the level supporting the communication of PDCP PDUs, a threshold may be configured by a network that can reuse the existing event A2 of the established handover procedure. The radio communication network can set multiple thresholds for event A2, i.e., one threshold when traffic is split, and a lower threshold when the same traffic is transmitted via both direct and indirect communication paths (Uu and SL), or based on the implementation of the network or UE. Thus, according to an exemplary embodiment, when the remote UE200 determines that a failure has occurred in the direct communication link with gNB100 via the Uu interface or has fallen below a predetermined threshold, the remote UE200 transmits an indication that the direct communication path can no longer support the communication of PDUs with gNB100 via the indirect communication path, i.e., via relay UEs 504a, 504b. According to an exemplary embodiment, based on this indication, the radio communication network can indicate to the remote UE200 to establish and communicate traffic (PDUs) via another communication link. The other communication link may be established with another gNB as part of a handover or via another relay UE (side link), or maintain a single link for a while. Further, the remote UE200 may report the status of the normally transmitted and received PDCP PDUs to identify the PDUs that were not normally transmitted and received. Because PDCP within gNB-CU can adjust for data loss and already has a framework for performing PDCP status reporting, it is good to report PDCP PDUs (performed in RLF and handover, and the UE reports the lost PDCP SN. This is known and is implemented in 38.300 / 38.323 and set by RRC38.331). However, it can also be done at the RLC layer.

[0038] Therefore, according to an exemplary embodiment, when the remote UE 200 detects that a failure has occurred in the Uu link or the Uu link quality has fallen below a threshold, it can notify the relay UE that the direct communication link via the Uu interface is no longer available to support data communication. The event that the Uu link quality has fallen below the threshold can be defined as event A2. When a failure occurs in the Uu link, the indication of this failure is sent to the gNB 100 via the sidelink (PC5), which is an indirect communication link, and the relay UE 300. According to an exemplary embodiment, the remote UE 200 then reports the status of the PDCP PDUs that have been successfully received or transmitted, so that the corresponding entity in the gNB 100 can identify the PDUs that have not been successfully transmitted or received.

[0039] SL Link Failure and Reporting to gNB Other exemplary embodiments are shown in FIG. 6, which corresponds to the exemplary embodiment of FIG. 5 and shows an example where a failure occurs in the indirect communication link to the relay UE 300 or the link quality falls below a predetermined threshold established for acceptable efficient communication integrity. In the example shown in FIG. 6, similar to the example of FIG. 5, during the initial stage 500, the remote UE 200 receives downlink data in the form of PDUs from the gNB 100 and transmits uplink data as PDUs to the gNB 100 using multi-path communication via a direct link (via the Uu interface) and an indirect communication link via the relay UE 300 (using the PC5 interface). However, at point 602, since the link quality of the PC5 interface with the relay UE 300 falls below a predetermined threshold or is considered to have failed, the communication path via the relay UE 300 is no longer available for the indirect communication link with the gNB 100. In this example, there already exists a procedure for the remote UE 200 to report a sidelink failure (SL-RLF) to the radio communication network via a direct communication link, i.e., via the Uu interface to the gNB 100. The reporting of the sidelink failure 604 is shown after detecting the sidelink failure or a degradation of the link quality below a predetermined threshold. Currently, the serving L2 U2N relay UE can use an existing event X2 (which has been conventionally used to trigger a handover) that becomes worse than an absolute threshold to send a message indicating that the link quality of the SL has fallen below a predetermined threshold or has failed. Next, the remote UE 200 reports the PDCP status to the gNB 100 via the direct communication link Uu interface as represented by the arrow 606.

[0040] According to this exemplary embodiment, event X2 is reported by the remote UE, whereby when a failure occurs in the direct communication link via the Uu interface, the PDCP status reporting procedure is triggered in a manner corresponding to the remote UE reporting the PDCP status report. According to some exemplary embodiments, event X2 used to trigger the identification that a failure or link quality is not sufficient to support efficient communication may be determined by comparing the link quality with different thresholds when multi-path communication is used for either redundancy or splitting between the direct communication path and the indirect communication path.

[0041] In some exemplary embodiments, the format and procedure of the PDCP status report triggered after event X2 may be configured by the radio communication network.

[0042] According to another exemplary embodiment represented by FIG. 6, the UE may have two or more SLs for two or more relay UEs 300 to communicate on an indirect communication path to the radio network infrastructure device. An RLF occurring in one or more of those SLs for one or more of those relay devices, such as in step 602, may in response cause the UE to transmit a Uu message via the Uu interface via the direct communication link of the multi-path communication link in step 604, which identifies the SL communication link for which the relay device is the affected RLF and may include, although it may be implicit, an indication of which of the SLs survived. For example, if there are only two SLs for two relay devices and one is affected by RLF, it is implicit that the other survived. However, generally, if there are N indirect or SLs between the UE and L relay devices and M of those SLs experience RLF, then N - M will have survived. The N - M surviving links may be implicitly indicated by indicating the M links that experienced RLF to the radio communication network, or the N - M surviving links may be explicitly indicated in the Uu message.

[0043] According to another exemplary embodiment, after establishing a multi-path communication link, the UE determines that the link quality of the indirect communication link can no longer support the communication of data units by transmitting data units to the radio network infrastructure device or by receiving data units from the radio network infrastructure device via the sidelink communication link, and via the direct communication link, indicates that the indirect communication link can no longer support the communication of data units, together with an indication that the indirect communication path has been released, and is configured to operate by transmitting, together with a status report of the transmission or reception of data units used to recover any of the lost data units. This indication is transmitted, for example, as a Uu message.

[0044] Both link failure and recovery via another relay UE Exemplary embodiments can also provide improvements when a failure occurs in both communication links of multi-path communication. FIG. 7 shows an exemplary embodiment showing procedures for recovering communication when failures occur in both the direct communication link and the indirect communication link. As shown in FIG. 7 and corresponding to other embodiments of FIGS. 5 and 6, at an initial stage 500, the remote UE 200 receives downlink data in the form of PDUs from the gNB 100, via the direct communication link (via the Uu interface), and via an indirect communication link via the relay UE 300 using the sidelink (PC5) interface, and transmits uplink data as PDUs to the gNB 100 using multi-path communication. However, at point 700, the link quality of both links of the PC5 interface with the gNB 100 falls below a predetermined threshold and is considered unable to support PDU communication or a failure has occurred, and the link quality of communication via the direct communication link of the Uu interface is also considered unable to support PDU communication or a failure has occurred, so the communication path via the gNB 100 directly via the remote UE 300 is no longer available. In this example, the remote UE 200 may discover another relay UE 702 in a discovery process 704 and indicate to re-establish a communication link with either the gNB 100 or another gNB, or to hand over to another gNB, before performing the RRC re-establishment procedure. When the remote UE 200 discovers the new relay UE 702, the remote UE 200 establishes a new sidelink connection 707 with the other remote UE 702. Thereafter, the remote UE 200 transmits a report 708 indicating a radio link failure of the Uu interface and the sidelink interface. The cell ID of the cell formed by the gNB 100 that has experienced a radio link failure in the Uu interface, and the identifier of the relay UE 300 (relay UE ID) for identifying the sidelink relay UE 300 where a radio link failure has also occurred, are included in the information transmitted to the other relay UE 702.This information can be included in either Message 1, Message 3, or Message 5, which is transmitted to the other remote UE 702 either before the activation of security as part of the random access procedure or after PDCP security is activated on the sidelink. That is, Uu PDCP security and SL PDCP security are established. SL security is peer-to-peer, and since this information is sent to the gNB, PDCP security is reasonable.

[0045] Therefore, according to an exemplary embodiment, the cell ID of the cell formed by the gNB that was providing services to the remote UE 200 where a radio link failure occurred, and the identifier of the relay UE where a radio link failure also occurred for identifying the sidelink relay UE, are included in the message transmitted from the remote UE to the new relay UE. Since the cell ID and the identifier of the relay UE that were used to provide multi-path communication are received, the wireless communication network can identify the UE context, and as a result, can re-establish the connection more quickly.

[0046] According to another exemplary embodiment, the sidelink communication link forming part of the multi-path communication may use a configured grant resource, for example, a sidelink configured grant type 1 (SL CG type 1 resource). When a radio link failure occurs on the direct communication link (Uu interface) and re-establishment is triggered, the configured grant resource for sidelink relay may still be valid even if the remote UE loses its connection to the master cell group (MCG) or cell. In this way, the remote UE can continue to use the configured grant type 1 resource for sidelink via the sidelink relay, so when an MCG radio link failure occurs, there is no need to stop using this type 1 resource and perform RRC re-establishment for sidelink communication. According to this exemplary embodiment, even if a radio link failure occurs on the direct communication link via the Uu interface, the configured grant resource for sidelink relay of the indirect communication link is maintained.

[0047] According to another exemplary embodiment, if the remote UE is supported by multi-path communication, the remote UE may be configured to prioritize the transmission of uplink data via either a sidelink or an uplink (direct communication link) to the gNB. This is because in some examples, the remote UE cannot perform simultaneous transmissions via the uplink Uu interface and the sidelink PC5 interface, for example, in the time domain. According to this exemplary embodiment, the transmission of data via the uplink or the sidelink is performed based on priorities and thresholds set by the radio communication network, i.e., the radio access network, or is pre-set. When the UE cannot perform both V2X sidelink transmission and uplink transmission simultaneously in the time domain, the prioritization between the two transmissions is performed based on priorities. According to this exemplary embodiment example, in multi-path communication, the remote UE notifies the gNB of the selected priority between the unicast transmission of the Uu interface and the sidelink of PC5. Therefore, since the remote UE notifies the gNB of the selected priority between the unicast of the UU interface and the PC-5 using the selected link, the network can invalidate or deactivate the multi-path configuration.

[0048] Establishment of multiple direct and / or indirect communication links by the UE In other exemplary embodiments, the UE may establish a multi-path communication link, and since a direct communication path is established using multiple carriers, i.e., a Uu interface with carrier aggregation or dual connectivity, communication can continue even if a failure occurs in communication on one carrier, and the RLF can be reported on any of the surviving carriers or via the surviving SL.

[0049] According to another exemplary embodiment, the UE may establish multi-path communication with a radio network infrastructure device of a wireless communication network including a plurality of direct communication links with the radio network infrastructure device and a plurality of indirect communication links via a plurality of relay communication devices each including an SL communication link with a relay device, and the plurality of relay communication devices provide a direct communication link with the radio network infrastructure device. The UE may be configured to transmit a data unit to the radio network infrastructure device using multi-path communication or to receive a data unit from the radio network infrastructure device using multi-path communication. And the UE is configured to determine that the link quality of one or more of the plurality of indirect communication links can no longer support the communication of the data unit by transmitting the data unit to the radio network infrastructure device or receiving the data unit from the radio network infrastructure device, or that the link quality of one or more of the plurality of direct communication links can no longer support the communication of the data unit by transmitting the data unit to the radio network infrastructure device or receiving the data unit from the radio network infrastructure device. The UE is also configured to identify the survival of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links, and transmit a display indicating that one or more of the plurality of direct communication links or one or more of the plurality of indirect communication links can no longer support the communication of the data unit via at least one surviving communication link. When at least one surviving communication link is an indirect communication link, the UE is configured to transmit a display of a cell identifier of a cell formed by the radio network infrastructure device and an identifier of the relay communication device forming the indirect communication link, which may be used by the wireless communication network to recover any of the lost data units.If at least one surviving communication link is a direct communication link that transmits a display of a cell identifier of a cell formed by a wireless network infrastructure device that forms the direct communication link, this can be used by the wireless communication network to recover any of the lost data units.

[0050] The following numbered paragraphs provide further illustrative aspects and features of the present technology. Paragraph 1 A method performed by a communication device to transmit data to or receive data from a wireless communication network, comprising: establishing multi-path communication with a wireless network infrastructure device of the wireless communication network, the multi-path communication including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a relay communication device that provides a second direct communication link with the wireless network infrastructure device and a sidelink communication link with the relay communication device; transmitting a data unit to the wireless network infrastructure device using the multi-path communication or receiving a data unit from the wireless network infrastructure device using the multi-path communication, the method comprising: determining that the link quality of the indirect communication link can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit via the sidelink communication link from the wireless network infrastructure device; transmitting, via the direct communication link, a display that the indirect communication link can no longer support communication of the data unit, together with a display that the indirect communication path has been released and a status report of the transmission or reception of the data unit, which is used to recover any of the lost data units. Paragraph 2 When it is determined that the link quality of the indirect communication link no longer supports the communication of the data unit, the status report transmitted to the radio network infrastructure device via the direct communication link is the data unit transmitted via the indirect communication link before it is determined that the indirect communication link no longer supports the communication of the data unit, or the data unit received from the indirect communication link before it is determined that the indirect communication link no longer supports the communication of the data unit, including the method described in Paragraph 1. Paragraph 3 When it is determined that the link quality of the indirect communication link does not no longer support the communication of the data unit, the status report is the data unit not transmitted via the indirect communication link as a result of determining that the indirect communication link can no longer support the communication of the data unit, or the last display of the data unit received from the indirect communication link before it is determined that the indirect communication link no longer supports the communication of the data unit, including the method described in Paragraph 1. Paragraph 4 The indication that the indirect communication link can no longer support the communication of the data unit, together with the indication that the indirect communication path has been released and the status report of the transmission or reception of the data unit, is transmitted to the radio network infrastructure device using a Uu message, including the method described in Paragraphs 1, 2 or 3. Paragraph 5 A method performed by a communication device for transmitting data to or receiving data from a wireless communication network, establishing multi-path communication with a radio network infrastructure device of the wireless communication network, the multi-path communication including a first direct communication link with the radio network infrastructure device and a plurality of indirect communication links via a plurality of relay communication devices including a plurality of sidelink communication links, each of the plurality of relay communication devices being capable of providing another direct communication link to the radio network infrastructure device; Transmitting a data unit to the wireless network infrastructure device using the multi-path communication, or receiving a data unit from the wireless network infrastructure device using the multi-path communication, the method comprising: Determining that at least one link quality of at least one of the indirect communication links with at least one of the plurality of relay devices can no longer support communication of the data unit, either by transmitting the data unit to the wireless network infrastructure device or by receiving the data unit via at least one of the sidelink communication links from the wireless network infrastructure device; Transmitting a display via the direct communication link of the one or more of the plurality of indirect communication links so determined that can no longer support communication of the data unit, along with a status report of the transmission or reception of the data unit, which is used for recovery of any of the lost data units and is released for use in recovery of any of the lost data units. Paragraph 6 A method performed by a communication device for transmitting data to, or receiving data from, a wireless communication network, the method comprising: Establishing multi-path communication with a wireless network infrastructure device of the wireless communication network, the multi-path communication including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a relay communication device including a sidelink communication link, the relay communication device providing a second direct communication link to the wireless network infrastructure device; Transmitting a data unit to the wireless network infrastructure device using the multi-path communication, or receiving a data unit from the wireless network infrastructure device using the multi-path communication, the method comprising: Determining that the link quality of the indirect communication link can no longer support communication of the data unit by transmitting the data unit to the radio network infrastructure device or receiving the data unit from the radio network infrastructure device; A method including transmitting, via the indirect communication link, an indication that the direct communication link can no longer support communication of the data unit. The method according to paragraph 6, comprising a status report of the transmission or reception of the data unit used for recovery of any of the lost data units in paragraph 7. Paragraph 8 If the link quality of the direct communication link is determined to no longer support communication of the data unit, the status report includes the data unit transmitted via the direct communication link before it is determined that the direct communication link no longer supports communication of the data unit, or the data unit received from the direct communication link before it is determined that the direct communication link no longer supports communication of the data unit. The method according to paragraph 6. Paragraph 9 If the link quality of the direct communication link is determined to no longer support communication of the data unit, the status report includes the data unit not transmitted via the direct communication link as a result of being determined that the direct communication link can no longer support communication of the data unit, or the last indication of the data unit received from the direct communication link before it is determined that the direct communication link no longer supports communication of the data unit. The method according to paragraph 6. Paragraph 10 The data unit is a packet data convergence protocol, PDCP, packet data unit, PDU, and the transmission and reception of the PDU are controlled by a PDCP layer connection with a PDCP layer in the radio network infrastructure device. The method according to any of paragraphs 1 to 9. Paragraph 11. The method according to any one of paragraphs 1 to 10, comprising the step of monitoring the link quality of one or both of the indirect communication link and the direct communication link, or receiving, from the radio network infrastructure device, a display of the link quality of one or both of the indirect communication link and the direct communication link, wherein determining that the link quality of the indirect communication link can no longer support the communication of the data unit includes determining that the link quality has fallen below a first predetermined threshold, and determining that the link quality of the direct communication link can no longer support the communication of the data unit includes determining that the link quality has fallen below a second predetermined threshold. Paragraph 12. The method according to paragraph 11, wherein the first predetermined threshold is the same as the second predetermined threshold. Paragraph 13. The method according to paragraph 11, wherein monitoring the link quality of the indirect communication link includes monitoring the link quality of the sidelink communication link with the relay communication device or receiving, from the radio network infrastructure device, a display of the link quality of the sidelink communication link with the relay communication device, and determining that the link quality of the indirect communication link can no longer support the communication of the data unit includes determining that the link quality of the sidelink communication link with the relay communication device has fallen below the second predetermined threshold. Paragraph 14. The method according to paragraph 11, wherein determining that the link quality of the indirect communication link can no longer support the communication of the data unit includes detecting that a radio link failure has occurred in the indirect communication link, and determining that the link quality of the direct communication link can no longer support the communication of the data unit includes detecting that a radio link failure has occurred in the direct communication link. Paragraph 15. The multi-path communication includes switching the data unit between the direct communication link and the indirect communication link to transmit the data unit, or replicating the data unit and transmitting the data unit to both the direct and the indirect communication links, or receiving the data unit transmitted between the direct communication link and the indirect communication link or replicated and transmitted on both the direct communication link and the indirect communication link by the wireless network infrastructure device switching, the method according to any one of paragraphs 1 to 14. Paragraph 16. A method performed by a communication device for transmitting data to or receiving data from a wireless communication network, comprising: establishing multi-path communication with a wireless network infrastructure device of the wireless communication network, the multi-path communication including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a first relay communication device including a sidelink communication link, the first relay communication device providing a second direct link to the wireless network infrastructure device; transmitting a data unit to the wireless network infrastructure device using the multi-path communication, or receiving a data unit from the wireless network infrastructure device using the multi-path communication; determining that the link quality of the indirect communication link can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device; determining that the link quality of the direct communication link can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device; discovering another communication device that can operate as a relay communication device; Establishing a new sidelink communication link with the discovered relay communication device that provides a third direct communication link with the wireless network infrastructure device or another wireless network infrastructure device; Transmitting, via the new sidelink communication link, an indication that the direct communication link and the indirect communication link can no longer support communication of the data unit; Transmitting a cell identifier of a cell formed by the wireless network infrastructure device and an identifier of the first relay communication device that can be used by the wireless communication network to recover any of the lost data units. A method comprising: Paragraph 17 A method performed by a communication device to transmit data to or receive data from a wireless communication network, the method comprising: Establishing multi-path communication with a wireless network infrastructure device of the wireless communication network, the multi-path communication including a plurality of direct communication links with the wireless network infrastructure device and a plurality of indirect communication links via a plurality of relay communication devices each including a sidelink communication link with the communication device, the plurality of relay communication devices being capable of providing a direct communication link to the wireless network infrastructure device; Transmitting a data unit to the wireless network infrastructure device using the multi-path communication, or receiving a data unit from the wireless network infrastructure device using the multi-path communication; Determining that the communication of the data unit can no longer be supported due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device by one or more link qualities of the plurality of indirect communication links, or Determining that the link quality of one or more of the plurality of direct communication links can no longer support communication of the data unit due to transmission of the data unit to the radio network infrastructure device or reception of the data unit from the radio network infrastructure device; Identifying at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links; and Transmitting an indication that communication of the data unit can no longer be supported via the at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links; If the at least one surviving communication link is an indirect communication link, transmitting a cell identifier of a cell formed by the radio network infrastructure device and an identifier of a relay communication device forming the indirect communication link that can be used by the wireless communication network to recover any of the lost data units; or If the at least one surviving communication link is a direct communication link, transmitting a cell identifier of a cell formed by the radio network infrastructure device forming the direct communication link that can be used by the wireless communication network to recover any of the lost data units, a method comprising. The method according to paragraph 17, comprising transmitting a status report via a new sidelink communication link, the status report indicating the status of the transmission or reception of the data unit, which is used to recover any of the data units lost as a result that the direct and indirect communication links can no longer support communication of the data unit. Paragraph 19 If the link quality of the indirect communication link and the direct communication link is determined to no longer support the communication of the data unit, the status report is the data unit transmitted via the indirect and direct communication links before it is determined that the communication of the data unit is no longer supported, or the display of the data unit received from the indirect and direct communication links before it is determined that the communication of the data unit is no longer supported, in the method described in Paragraph 18. Paragraph 20 If the link quality of the indirect communication link and the direct communication link is determined to no longer support the communication of the data unit, the status report is the method described in Paragraph 18, including the data unit not transmitted as a result of the determination that the indirect and direct communication links can no longer support the communication of the data unit, or the last display of the data unit received from the indirect and direct communication links before it is determined that the communication of the data unit is no longer supported. Paragraph 21 The data unit is a packet data convergence protocol, PDCP, packet data unit, PDU, and the transmission and reception of the PDU is controlled by a PDCP layer connection with the PDCP layer in the radio network infrastructure device, in the method described in any of Paragraphs 18, 19, or 20. Paragraph 22 includes the step of monitoring the link quality of the indirect communication link and the direct communication link, or receiving a display of the link quality of the indirect communication link and the direct communication link from the radio network infrastructure device, and determining that the link quality of the indirect communication link can no longer support the communication of the data unit includes determining that the link quality is below a first predetermined threshold, and determining that the link quality of the direct communication link can no longer support the communication of the data unit includes determining that the link quality is below a second predetermined threshold, in the method described in any of Paragraphs 17 to 21. Paragraph 23 The method described in Paragraph 22, where the first predetermined threshold is the same as the second predetermined threshold. Paragraph 24 The multi-path communication includes transmitting the data unit by splitting it between the direct communication link and the indirect communication link, or by duplicating the data unit and transmitting the data unit to both the direct and the indirect communication links, or receiving the data unit transmitted by the wireless network infrastructure device switched between the direct communication link and the indirect communication link, or duplicated and transmitted on both the direct and the indirect communication links, the method according to any one of paragraphs 16 to 23. Paragraph 25 A method executed by a communication device for transmitting data to or receiving data from a wireless communication network, comprising: establishing multi-path communication with a wireless network infrastructure device of the wireless communication network, the multi-path communication including a plurality of direct communication links with the wireless network infrastructure device and a plurality of indirect communication links via a plurality of relay communication devices each including a sidelink communication link with the communication device, the plurality of relay communication devices being capable of providing a direct communication link to the wireless network infrastructure device; transmitting a data unit to the wireless network infrastructure device using the multi-path communication, or receiving a data unit from the wireless network infrastructure device using the multi-path communication; determining that the communication of the data unit can no longer be supported due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device, for one or more link qualities of the plurality of indirect communication links, or determining that the communication of the data unit can no longer be supported due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device, for one or more link qualities of the plurality of direct communication links; identifying at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links; and transmitting an indication that communication of the data unit can no longer be supported via at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links; and when the at least one surviving communication link is an indirect communication link, transmitting a cell identifier of a cell formed by the radio network infrastructure device and an identifier of a relay communication device forming the indirect communication link that can be used by the radio communication network to recover any of the lost data units; when the at least one surviving communication link is a direct communication link, transmitting a cell identifier of a cell formed by the radio network infrastructure device forming the direct communication link that can be used by the radio communication network to recover any of the lost data units, the method comprising: Paragraph 26. A method according to paragraph 25, comprising transmitting a status report via a surviving communication link, the status report indicating a status of the transmission or reception of the data unit, which is used to recover any of the data units lost as a result of the direct and indirect communication links no longer being able to support communication of the data unit. Paragraph 27. The method according to any of paragraphs 25 or 26, wherein the data unit is a packet data convergence protocol, PDCP, packet data unit, PDU, and the transmission and reception of the PDU is controlled by a PDCP layer connection with a PDCP layer within the radio network infrastructure device. Paragraph 28. The method according to any one of paragraphs 25 to 27, comprising the step of monitoring the link quality of the indirect communication link and the direct communication link, or receiving, from the radio network infrastructure device, a display of the link quality of the indirect communication link and the direct communication link, wherein determining that the link quality of one or more of the plurality of indirect communication links can no longer support the communication of the data unit includes determining that the link quality has fallen below a first predetermined threshold, and determining that the link quality of one or more of the plurality of direct communication links can no longer support the communication of the data unit includes determining that the link quality has fallen below a second predetermined threshold. Paragraph 29. The method according to paragraph 28, wherein the first predetermined threshold is the same as the second predetermined threshold. Paragraph 30. The method according to any one of paragraphs 25 to 29, wherein the multi-path communication includes dividing the data unit between the plurality of direct communication links and the plurality of indirect communication links and transmitting the data unit, or replicating the data unit and transmitting the data unit to the plurality of direct communication links and the plurality of indirect communication links, or receiving the data unit transmitted by the radio network infrastructure device switched between the plurality of direct communication links and the plurality of indirect communication links, or replicated and transmitted over both the direct and indirect communication links. Paragraph 31. A method performed by a communication device for transmitting data to, or receiving data from, a wireless communication network, comprising: establishing multi-path communication with a radio network infrastructure device of the wireless communication network, the multi-path communication including a first direct communication link with the radio network infrastructure device and an indirect communication link via a relay communication device including a sidelink communication link with a second direct communication link with the radio network infrastructure device; The step of transmitting a data unit to the wireless network infrastructure device using the multi-path communication, or the step of receiving a data unit from the wireless network infrastructure device using the multi-path communication, wherein the sidelink communication link with the relay communication device is formed from the set grant resources of the sidelink radio interface, and the method comprises: Determining that the link quality of the direct communication link can no longer support the communication of the data unit due to the transmission of the data unit to the wireless network infrastructure device or the reception of the data unit from the wireless network infrastructure device; Executing a re-establishment procedure to re-establish the direct communication link with the wireless network infrastructure device; Transmitting the data unit to the wireless network infrastructure device using the re-established direct communication link according to the multi-path communication, or receiving the data unit from the wireless network infrastructure device using the re-established direct communication link, and transmitting the data unit to the wireless network infrastructure device using the set grant resources already established for the sidelink communication link, or receiving the data unit from the wireless network infrastructure device using the set grant resources already established for the sidelink communication link. A method comprising the steps of. Paragraph 32 A method performed by a communication device for transmitting data to or receiving data from a wireless communication network, comprising: Establishing multi-path communication with a wireless network infrastructure device of the wireless communication network, the multi-path communication comprising a first direct communication link with the wireless network infrastructure device and an indirect communication link via a relay communication device comprising a sidelink communication link with the relay communication device providing a second direct communication link with the wireless network infrastructure device; Transmitting or receiving a data unit to / from the wireless network infrastructure device using the multi-path communication, wherein the step of transmitting a data unit to the wireless network infrastructure device using the multi-path communication comprises Determining, using the indirect communication link and the direct communication link, that the data unit of the uplink cannot be simultaneously transmitted to the wireless network infrastructure device; Prioritizing the transmission of the uplink data unit by selecting either the indirect communication link via the sidelink communication link or the direct communication link; Transmitting the data unit to the wireless network infrastructure device using the selected sidelink communication link or the selected direct communication link. A method comprising the above steps. The method according to paragraph 32, comprising transmitting, to the wireless network infrastructure device, an indication of one selected from the indirect communication link or the direct communication link via the sidelink communication link, wherein the multi-path communication is disabled for the uplink. A communication device for transmitting data to or receiving data from a wireless communication network, comprising A transceiver circuit configured to transmit or receive signals to / from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device; Controlling the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a relay communication device providing a second direct communication link to the wireless network infrastructure device, the indirect communication link including a sidelink communication link; A controller circuit configured to transmit a data unit to the wireless network infrastructure device using the multi-path communication or to receive a data unit from the wireless network infrastructure device using the multi-path communication, the controller circuit determines that the link quality of the indirect communication link can no longer support the communication of the data unit due to the transmission of the data unit to the wireless network infrastructure device or the reception of the data unit from the wireless network infrastructure device, and is configured to control the transmitter circuit to transmit, via the direct communication link, an indication that the indirect communication link can no longer support the communication of the data unit, together with an indication that the indirect communication path has been released and a status report of the transmission or reception of the data unit used for the recovery of any lost data unit, to the wireless network infrastructure device. Paragraph 35 A communication device for transmitting data to or receiving data from a wireless communication network, comprising a transceiver circuit configured to transmit or receive signals to or from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device, controls the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a first direct communication link with the wireless network infrastructure device and a plurality of indirect communication links via a plurality of relay communication devices each providing another direct communication link to the wireless network infrastructure device, a controller circuit configured to transmit a data unit to the wireless network infrastructure device using the multi-path communication or to receive a data unit from the wireless network infrastructure device using the multi-path communication, the controller circuit At least one link quality of at least one of the plurality of relay devices for the indirect communication link is determined to no longer support communication of the data unit by transmission of the data unit to the wireless network infrastructure device or by reception of the data unit from the wireless network infrastructure device via at least one of the sidelink communication links, and A communication device configured to transmit a display via a direct communication link of one or more of the plurality of indirect communication links that are determined to no longer support communication of the data unit, which is used for recovery of any of the lost data units and is released together with a status report of the transmission or reception of the data unit for recovery of any of the lost data units. Paragraph 36 A communication device for transmitting data to or receiving data from a wireless communication network, A transceiver circuit configured to transmit or receive a signal to or from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device, The transceiver circuit is controlled to establish multi-path communication with the wireless network infrastructure device of the wireless communication network including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a relay communication device that provides a second direct communication link to the wireless network infrastructure device, A controller circuit configured to transmit a data unit to the wireless network infrastructure device using the multi-path communication or to receive a data unit from the wireless network infrastructure device using the multi-path communication, and the controller circuit The link quality of the direct communication link is determined to no longer support the communication of the data unit by transmitting the data unit to the wireless network infrastructure device or by receiving the data unit from the wireless network infrastructure device, and A communication device configured to control the transmitter circuit to transmit, via the indirect communication link, an indication that the direct communication link can no longer support the communication of the data unit, together with a status report of the transmission or reception of the data unit used for the recovery of any of the lost data units. Paragraph 37 A communication device for transmitting data to or receiving data from a wireless communication network, comprising A transceiver circuit configured to transmit or receive signals to or from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device, A controller circuit configured to control the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a first relay communication device that provides a second direct communication link to the wireless network infrastructure device, The controller circuit is configured to transmit a data unit to the wireless network infrastructure device using the multi-path communication or to receive a data unit from the wireless network infrastructure device using the multi-path communication, and The link quality of the indirect communication link is determined to no longer support the communication of the data unit by transmitting the data unit to the wireless network infrastructure device or by receiving the data unit from the wireless network infrastructure device, and It is determined that the link quality of the direct communication link can no longer support the communication of the data unit due to the transmission of the data unit to the wireless network infrastructure device or the reception of the data unit from the wireless network infrastructure device. Discover other communication devices that can operate as relay communication devices. Establish a new sidelink communication link with the discovered relay communication device that provides a third direct communication link with the wireless network infrastructure device or another wireless network infrastructure device. Control the transmitter circuit to transmit an indication that the direct communication link and the indirect communication link can no longer support the communication of the data unit via the new sidelink communication link, and A communication device configured to control the transmitter circuit to transmit an indication of a cell identifier of a cell formed by the wireless network infrastructure device and an identifier of the first relay communication device that can be used by the wireless communication network to recover any of the lost data units. Paragraph 38 A communication device for transmitting data to or receiving data from a wireless communication network, A transceiver circuit configured to transmit or receive signals to or from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device, Control the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a plurality of direct communication links with the wireless network infrastructure device and a plurality of indirect communication links via a plurality of relay communication devices that each provide a direct communication link to the wireless network infrastructure device and include a sidelink communication link with the communication device. A controller circuit configured to transmit a data unit to the wireless network infrastructure device using the multi-path communication or to receive a data unit from the wireless network infrastructure device using the multi-path communication, the controller circuit wherein at least one link quality of the plurality of indirect communication links is determined to no longer support communication of the data unit by transmitting the data unit to the wireless network infrastructure device or by receiving the data unit from the wireless network infrastructure device, or wherein at least one link quality of the plurality of direct communication links is determined to no longer support communication of the data unit by transmitting the data unit to the wireless network infrastructure device or by receiving the data unit from the wireless network infrastructure device, identifying at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links, and controlling the transceiver circuit to transmit an indication that communication of the data unit can no longer be supported via at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links, and when the at least one surviving communication link is an indirect communication link, controlling the transceiver circuit to transmit a cell identifier of a cell formed by the wireless network infrastructure device and an identifier of a relay communication device forming the indirect communication link that can be used by the wireless communication network to recover any of the lost data units, or when the at least one surviving communication link is a direct communication link, a communication device configured to control the transceiver circuit to transmit a cell identifier of a cell formed by the wireless network infrastructure device forming the direct communication link that can be used by the wireless communication network to recover any of the lost data units. A communication device for transmitting data to or receiving data from a wireless communication network, a transceiver circuit configured to transmit or receive signals to or from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device; controlling the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a first direct communication link with the wireless network infrastructure device, providing a second direct communication link to the wireless network infrastructure device, and an indirect communication link via a relay communication device including a side-link communication link with the relay communication device; transmitting a data unit to the wireless network infrastructure device using the multi-path communication or receiving a data unit from the wireless network infrastructure device using the multi-path communication, the side-link communication link with the relay communication device including a controller circuit configured to be formed from a set grant resource of a side-link radio interface, the controller circuit determining that the link quality of the direct communication link can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device; performing a re-establishment procedure to re-establish the direct communication link with the wireless network infrastructure device; The communication device is configured to control the transceiver circuit to transmit the data unit to the wireless network infrastructure device using the re-established direct communication link according to multi-path communication, or to receive the data unit from the wireless network infrastructure device using the re-established direct communication link, and to transmit the data unit to the wireless network infrastructure device using the set grant resource already established for the sidelink communication link, or to receive the data unit from the wireless network infrastructure device using the set grant resource already established for the sidelink communication link. Paragraph 40 A communication device for transmitting data to or receiving data from a wireless communication network, comprising: a transceiver circuit configured to transmit or receive signals to or from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device; control the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a relay communication device including a second direct communication link to the wireless network infrastructure device and a sidelink communication link with the relay communication device; a controller circuit configured to control the transceiver unit to transmit a data unit to the wireless network infrastructure device or receive a data unit from the wireless network infrastructure device using the multi-path communication, the controller circuit using the indirect communication link and the direct communication link, determines that the data unit of the uplink cannot be simultaneously transmitted to the wireless network infrastructure device; By selecting either the indirect communication link or the direct communication link via the sidelink communication link, the transmission of uplink data units is prioritized, and A communication device configured to control the transceiver circuit to transmit a data unit to a radio network infrastructure device using multi-path communication by transmitting the data unit to the radio network infrastructure device using either the selected sidelink communication link or the selected direct communication link.

[0051] Although the present disclosure has been described in connection with several embodiments, it is not intended to be limited to the specific forms defined herein. Further, although a feature may appear to be described in connection with a particular embodiment, one of ordinary skill in the art will recognize that the various features of the described embodiments can be combined in any manner suitable for implementing the technology.

[0052] Reference [1] TS 38.470 [2] TS 38.423 [3] TS 38.300 [4] TS 38.323 [5] TS 38.331

Claims

1. A method performed by a communication device for transmitting data to or receiving data from a wireless communication network, comprising: establishing multi-path communication with wireless network infrastructure equipment of the wireless communication network, the multi-path communication including a first direct communication link with the wireless network infrastructure equipment and an indirect communication link via a relay communication device that provides a second direct communication link with the wireless network infrastructure equipment and a sidelink communication link with the relay communication device; transmitting a data unit to the wireless network infrastructure equipment using the multi-path communication, or receiving a data unit from the wireless network infrastructure equipment using the multi-path communication, the method further comprising determining that the link quality of the indirect communication link no longer supports communication of the data unit due to transmission of the data unit to the wireless network infrastructure equipment or reception of the data unit via the sidelink communication link from the wireless network infrastructure equipment; transmitting, via the direct communication link, an indication that the indirect communication link no longer supports communication of the data unit, together with an indication that the indirect communication path has been released and a status report of the transmission or reception of the data unit, for use in recovering any lost data units.

2. The method according to claim 1, wherein when it is determined that the link quality of the indirect communication link no longer supports communication of the data unit, the status report transmitted to the wireless network infrastructure equipment via the direct communication link includes an indication of the data unit transmitted via the indirect communication link or received from the indirect communication link before it is determined that the indirect communication link no longer supports communication of the data unit.

3. If it is determined that the link quality of the indirect communication link does not no longer support the communication of the data unit, the status report is, as a result of determining that the indirect communication link can no longer support the communication of the data unit, a data unit not transmitted via the indirect communication link, or the last indication of the data unit received from the indirect communication link before it is determined that the indirect communication link can no longer support the communication of the data unit, the method according to claim 1.

4. The indication that the indirect communication link can no longer support the communication of the data unit is transmitted to the radio network infrastructure device using a Uu message, together with the indication that the indirect communication path has been released and the status report of the transmission or reception of the data unit, according to the method of claim 1, 2 or 3.

5. A method performed by a communication device for transmitting data to or receiving data from a wireless communication network, comprising: establishing multi-path communication with a radio network infrastructure device of the wireless communication network, the multi-path communication including a first direct communication link with the radio network infrastructure device and a plurality of indirect communication links via a plurality of relay communication devices including a plurality of sidelink communication links, each of the plurality of relay communication devices being capable of providing another direct communication link to the radio network infrastructure device; transmitting a data unit to the radio network infrastructure device using the multi-path communication, or receiving a data unit from the radio network infrastructure device using the multi-path communication, the method comprising: determining that at least one link quality of at least one of the indirect communication links with at least one of the plurality of relay devices no longer supports the communication of the data unit due to the transmission of the data unit to the radio network infrastructure device or the reception of the data unit via at least one of the sidelink communication links from the radio network infrastructure device; A method comprising: transmitting a display via the direct communication link of the determined one or more of the plurality of indirect communication links that cannot support communication of the data unit any longer and are released together with a status report of the transmission or reception of the data unit used for recovery of any of the lost data units for recovery of any of the lost data units.

6. A method performed by a communication device for transmitting data to or receiving data from a wireless communication network, the method comprising: establishing multi-path communication with wireless network infrastructure equipment of the wireless communication network, the multi-path communication including a first direct communication link with the wireless network infrastructure equipment and an indirect communication link via a relay communication device including a sidelink communication link, the relay communication device providing a second direct communication link to the wireless network infrastructure equipment; transmitting a data unit to the wireless network infrastructure equipment using the multi-path communication or receiving a data unit from the wireless network infrastructure equipment using the multi-path communication, the method further comprising: determining that link quality of the indirect communication link can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure equipment or reception of the data unit from the wireless network infrastructure equipment; transmitting, via the indirect communication link, a display that the direct communication link can no longer support communication of the data unit.

7. The method according to claim 6, further comprising a status report of the transmission or reception of the data unit used for recovery of any of the lost data units.

8. The method according to claim 6, wherein when it is determined that the link quality of the direct communication link no longer supports the communication of the data unit, the status report is the data unit transmitted via the direct communication link before it is determined that the direct communication link no longer supports the communication of the data unit, or the display of the data unit received from the direct communication link before it is determined that the direct communication link no longer supports the communication of the data unit.

9. The method according to claim 6, wherein when it is determined that the link quality of the direct communication link no longer supports the communication of the data unit, the status report is the data unit not transmitted via the direct communication link as a result of being determined that the direct communication link can no longer support the communication of the data unit, or the last display of the data unit received from the direct communication link before it is determined that the direct communication link no longer supports the communication of the data unit.

10. The method according to any one of claims 1 to 9, wherein the data unit is a Packet Data Convergence Protocol, PDCP, packet data unit, PDU, and the transmission and reception of the PDU are controlled by a PDCP layer connection with a PDCP layer in the radio network infrastructure device.

11. The method according to any one of claims 1 to 10, comprising the step of monitoring the link quality of one or both of the indirect communication link and the direct communication link, or the step of receiving a display of the link quality of one or both of the indirect communication link and the direct communication link from the radio network infrastructure device, wherein determining that the link quality of the indirect communication link can no longer support the communication of the data unit includes determining that the link quality has fallen below a first predetermined threshold, and determining that the link quality of the direct communication link can no longer support the communication of the data unit includes determining that the link quality has fallen below a second predetermined threshold.

12. The method according to claim 11, wherein the first predetermined threshold is the same as the second predetermined threshold.

13. Monitoring the link quality of the indirect communication link includes monitoring the link quality of the sidelink communication link with the relay communication device or receiving an indication of the link quality of the sidelink communication link with the relay communication device from the wireless network infrastructure device. Determining that the link quality of the indirect communication link can no longer support communication of the data unit includes determining that the link quality of the sidelink communication link with the relay communication device has fallen below a second predetermined threshold. The method according to claim 11.

14. Determining that the link quality of the indirect communication link can no longer support communication of the data unit includes detecting that a wireless link failure has occurred on the indirect communication link. Determining that the link quality of the direct communication link can no longer support communication of the data unit includes detecting that a wireless link failure has occurred on the direct communication link. The method according to claim 11.

15. The multi-path communication includes switching the data unit between the direct communication link and the indirect communication link to transmit the data unit, or replicating the data unit and transmitting the data unit to both the direct and the indirect communication links, or receiving the data unit transmitted between the direct communication link and the indirect communication link or replicated and transmitted on both the direct communication link and the indirect communication link by switching of the wireless network infrastructure device. The method according to any one of claims 1 to 14.

16. A method performed by a communication device for transmitting data to or receiving data from a wireless communication network, comprising: Establishing multi-path communication with a wireless network infrastructure device of the wireless communication network, the multi-path communication including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a first relay communication device including a sidelink communication link, the first relay communication device providing a second direct link to the wireless network infrastructure device. The step of transmitting a data unit to the wireless network infrastructure device using the multi-path communication, or the step of receiving a data unit from the wireless network infrastructure device using the multi-path communication; The step of determining that the link quality of the indirect communication link can no longer support the communication of the data unit due to the transmission of the data unit to the wireless network infrastructure device or the reception of the data unit from the wireless network infrastructure device; The step of determining that the link quality of the direct communication link can no longer support the communication of the data unit due to the transmission of the data unit to the wireless network infrastructure device or the reception of the data unit from the wireless network infrastructure device; The step of discovering another communication device that can operate as a relay communication device; The step of establishing a new side-link communication link with the discovered relay communication device that provides a third direct communication link with the wireless network infrastructure device or another wireless network infrastructure device; The step of transmitting, via the new side-link communication link, an indication that the direct communication link and the indirect communication link can no longer support the communication of the data unit; The step of transmitting an identifier of a cell formed by the wireless network infrastructure device and an identifier of the first relay communication device, which can be used by the wireless communication network to recover any of the lost data units, including a method.

17. A method performed by a communication device for transmitting data to a wireless communication network or receiving data from a wireless communication network, comprising: A step of establishing multi-path communication with a wireless network infrastructure device of the wireless communication network, wherein the multi-path communication includes a plurality of direct communication links with the wireless network infrastructure device and a plurality of indirect communication links via a plurality of relay communication devices each including a sidelink communication link with the communication device, and the plurality of relay communication devices can provide a direct communication link to the wireless network infrastructure device; A step of transmitting a data unit to the wireless network infrastructure device using the multi-path communication, or a step of receiving a data unit from the wireless network infrastructure device using the multi-path communication; A step of determining that the communication of the data unit can no longer be supported due to the transmission of the data unit to the wireless network infrastructure device or the reception of the data unit from the wireless network infrastructure device for one or more link qualities of the plurality of indirect communication links, or A step of determining that the communication of the data unit can no longer be supported due to the transmission of the data unit to the wireless network infrastructure device or the reception of the data unit from the wireless network infrastructure device for one or more link qualities of the plurality of direct communication links; A step of identifying at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links; and A step of transmitting a indication that the communication of the data unit can no longer be supported via at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links; When the at least one surviving communication link is an indirect communication link, transmitting an identifier of a cell formed by the wireless network infrastructure device and an identifier of a relay communication device forming the indirect communication link, which can be used by the wireless communication network to recover any of the lost data units; or when the at least one surviving communication link is a direct communication link, transmitting an identifier of a cell formed by the wireless network infrastructure device forming the direct communication link, which can be used by the wireless communication network to recover any of the lost data units, the method comprising the steps of.

18. The method according to claim 17, comprising the step of transmitting a status report via a new sidelink communication link, the status report indicating the status of the transmission or reception of the data unit, which is used to recover any of the data units lost as a result of the direct and indirect communication links no longer being able to support the communication of the data unit.

19. If the link quality of the indirect communication link and the direct communication link is determined to no longer support the communication of the data unit, the status report includes the data units transmitted via the indirect and direct communication links before it was determined that the indirect and direct communication links no longer support the communication of the data unit, or the representation of the data units received from the indirect and direct communication links before it was determined that the indirect and direct communication links no longer support the communication of the data unit, the method according to claim 18.

20. If the link quality of the indirect communication link and the direct communication link is determined to no longer support the communication of the data unit, the status report is The method according to claim 18, including data units not transmitted as a result of the indirect and direct communication links being determined to no longer support the communication of the data unit, or the last representation of the data units received from the indirect and direct communication links before it was determined that the indirect and direct communication links no longer support the communication of the data unit.

21. The data unit is a Packet Data Convergence Protocol, PDCP, packet data unit, PDU, and transmission and reception of the PDU are controlled by a PDCP layer connection with a PDCP layer in the wireless network infrastructure device, the method according to any one of claims 18, 19 or 20.

22. The method according to any one of claims 17 to 21, comprising monitoring the link quality of the indirect communication link and the direct communication link, or receiving, from the wireless network infrastructure device, a display of the link quality of the indirect communication link and the direct communication link, wherein determining that the link quality of the indirect communication link can no longer support communication of the data unit includes determining that the link quality has fallen below a first predetermined threshold, and determining that the link quality of the direct communication link can no longer support communication of the data unit includes determining that the link quality has fallen below a second predetermined threshold.

23. The method according to claim 22, wherein the first predetermined threshold is the same as the second predetermined threshold.

24. The method according to any one of claims 16 to 23, wherein the multi-path communication includes splitting and transmitting the data unit between the direct communication link and the indirect communication link, or replicating the data unit and transmitting the data unit to both the direct and the indirect communication links, or receiving the data unit transmitted by the wireless network infrastructure device switched between the direct communication link and the indirect communication link, or replicated and transmitted over both the direct and the indirect communication links.

25. A method performed by a communication device for transmitting data to, or receiving data from, a wireless communication network, comprising: Establishing multi-path communication with the wireless network infrastructure equipment of the wireless communication network, wherein the multi-path communication includes a plurality of direct communication links with the wireless network infrastructure equipment and a plurality of indirect communication links via a plurality of relay communication devices each including a side-link communication link with the communication device, and the plurality of relay communication devices can provide a direct communication link to the wireless network infrastructure equipment; Transmitting a data unit to the wireless network infrastructure equipment using the multi-path communication, or receiving a data unit from the wireless network infrastructure equipment using the multi-path communication; Determining that the communication of the data unit can no longer be supported due to the transmission of the data unit to the wireless network infrastructure equipment or the reception of the data unit from the wireless network infrastructure equipment for one or more link qualities of the plurality of indirect communication links, or Determining that the communication of the data unit can no longer be supported due to the transmission of the data unit to the wireless network infrastructure equipment or the reception of the data unit from the wireless network infrastructure equipment for one or more link qualities of the plurality of direct communication links; Identifying at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links; and Transmitting an indication that the communication of the data unit can no longer be supported via at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links; and When the at least one surviving communication link is an indirect communication link, transmitting the cell identifier of the cell formed by the wireless network infrastructure equipment and the identifier of the relay communication device forming the indirect communication link that can be used by the wireless communication network to recover any of the lost data units; When the at least one surviving communication link is a direct communication link, transmitting a cell identifier of a cell formed by the wireless network infrastructure device forming the direct communication link, which can be used by the wireless communication network to recover any of the lost data units. A method comprising the steps of.

26. Including the step of transmitting a status report via a surviving communication link, the status report being used to recover any of the data units lost as a result of the direct and indirect communication links no longer being able to support the communication of the data units, indicating the status of the transmission or reception of the data units. The method according to claim 25.

27. The data unit is a Packet Data Convergence Protocol, PDCP, packet data unit, PDU, and the transmission and reception of the PDU are controlled by a PDCP layer connection with a PDCP layer within the wireless network infrastructure device. The method according to any one of claims 25 or 26.

28. Monitoring the link quality of the indirect communication link and the direct communication link, or receiving a display of the link quality of the indirect communication link and the direct communication link from the wireless network infrastructure device, wherein determining that the link quality of one or more of the plurality of indirect communication links can no longer support the communication of the data unit includes determining that the link quality has fallen below a first predetermined threshold, and determining that the link quality of one or more of the plurality of direct communication links can no longer support the communication of the data unit includes determining that the link quality has fallen below a second predetermined threshold. The method according to any one of claims 25 to 27.

29. The method according to claim 28, wherein the first predetermined threshold is the same as the second predetermined threshold.

30. The multi-path communication according to any one of claims 25 to 29 includes dividing the data unit between the plurality of direct communication links and the plurality of indirect communication links and transmitting the data unit, or replicating the data unit and transmitting the data unit to the plurality of direct communication links and the plurality of indirect communication links, or receiving the data unit transmitted by the wireless network infrastructure device switched between the plurality of direct communication links and the plurality of indirect communication links, or replicated and transmitted over both the direct and indirect communication links.

31. A method performed by a communication device for transmitting data to or receiving data from a wireless communication network, the method comprising: establishing multi-path communication with a wireless network infrastructure device of the wireless communication network, the multi-path communication including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a relay communication device including a sidelink communication link with the relay communication device providing a second direct communication link with the wireless network infrastructure device; transmitting a data unit to the wireless network infrastructure device using the multi-path communication, or receiving a data unit from the wireless network infrastructure device using the multi-path communication, wherein the sidelink communication link with the relay communication device is formed from configured grant resources of a sidelink radio interface, and the method further comprises: determining that the link quality of the direct communication link no longer supports communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device; performing a re-establishment procedure to re-establish the direct communication link with the wireless network infrastructure device. A method comprising: transmitting the data unit to the wireless network infrastructure device using the re-established direct communication link according to multi-path communication, or receiving the data unit from the wireless network infrastructure device using the re-established direct communication link; and transmitting the data unit to the wireless network infrastructure device using a configured grant resource already established for the sidelink communication link, or receiving the data unit from the wireless network infrastructure device using a configured grant resource already established for the sidelink communication link.

32. A method performed by a communication device for transmitting data to, or receiving data from, a wireless communication network, the method comprising: establishing multi-path communication with a wireless network infrastructure device of the wireless communication network, the multi-path communication including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a relay communication device including a sidelink communication link with the relay communication device providing a second direct communication link with the wireless network infrastructure device; transmitting or receiving a data unit to or from the wireless network infrastructure device using the multi-path communication, the step of transmitting a data unit to the wireless network infrastructure device using the multi-path communication comprising: determining that the data unit of the uplink cannot be simultaneously transmitted to the wireless network infrastructure device using the indirect communication link and the direct communication link; prioritizing transmission of an uplink data unit by selecting either the indirect communication link via the sidelink communication link or the direct communication link; transmitting the data unit to the wireless network infrastructure device using either the selected sidelink communication link or the selected direct communication link.

33. including the step of transmitting a selected one of the indirect communication link or the direct communication link via the sidelink communication link to the wireless network infrastructure device, wherein the multi-path communication is disabled for the uplink, the method according to claim 32.

34. A communication device for transmitting data to or receiving data from a wireless communication network, comprising: a transceiver circuit configured to transmit or receive signals to or from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device; controlling the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a relay communication device providing a second direct communication link to the wireless network infrastructure device; a controller circuit configured to transmit a data unit to the wireless network infrastructure device using the multi-path communication or to receive a data unit from the wireless network infrastructure device using the multi-path communication, the controller circuit being: determining that the link quality of the indirect communication link can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device; and configured to control the transmitter circuit to transmit, via the direct communication link, a indication that the indirect communication link can no longer support communication of the data unit, together with an indication that the indirect communication path has been released and a status report of the transmission or reception of the data unit for use in recovering any of the lost data units, a communication device.

35. A communication device for transmitting data to or receiving data from a wireless communication network, comprising: A transceiver circuit configured to transmit a signal to, or receive a signal from, one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device; A controller circuit configured to control the transceiver circuit to establish multi-path communication with a wireless network infrastructure device of the wireless communication network, including a first direct communication link with the wireless network infrastructure device and a plurality of indirect communication links via the plurality of relay communication devices each providing another direct communication link to the wireless network infrastructure device; A controller circuit configured to transmit a data unit to the wireless network infrastructure device using the multi-path communication or receive a data unit from the wireless network infrastructure device using the multi-path communication, the controller circuit comprising: Determining that at least one link quality of at least one of the indirect communication links with at least one of the plurality of relay devices can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device via at least one of the side-link communication links; and A communication device configured to transmit a display via the direct communication link of the one or more of the plurality of indirect communication links determined to no longer support communication of the data unit, along with a status report of the transmission or reception of the data unit, for use in recovery of any of the lost data units, released for use in recovery of any of the lost data units;

36. A communication device for transmitting data to, or receiving data from, a wireless communication network, comprising: A transceiver circuit configured to transmit a signal to, or receive a signal from, one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device; Controlling the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a first direct communication link with the wireless network infrastructure device and an indirect communication link via the relay communication device including a side-link communication link with a relay communication device that provides a second direct communication link to the wireless network infrastructure device, including a controller circuit configured to transmit a data unit to the wireless network infrastructure device using the multi-path communication or receive a data unit from the wireless network infrastructure device using the multi-path communication, the controller circuit determines that the link quality of the direct communication link can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device, and is configured to control the transmitter circuit to transmit, via the indirect communication link, an indication that the direct communication link can no longer support communication of the data unit, along with a status report of the transmission or reception of the data unit used for recovery of any of the lost data units, a communication device.

37. A communication device for transmitting data to or receiving data from a wireless communication network, a transceiver circuit configured to transmit or receive signals to or from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device, controlling the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a first relay communication device including a side-link communication link with a first relay communication device that provides a second direct communication link to the wireless network infrastructure device, A controller circuit configured to transmit a data unit to the wireless network infrastructure device using the multi-path communication or to receive a data unit from the wireless network infrastructure device using the multi-path communication, the controller circuit determines that the link quality of the indirect communication link can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device, and determines that the link quality of the direct communication link can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device, discovers another communication device that can operate as a relay communication device, establishes a new side-link communication link with the discovered relay communication device that provides a third direct communication link with the wireless network infrastructure device or another wireless network infrastructure device, controls the transmitter circuit to transmit an indication that the direct communication link and the indirect communication link can no longer support communication of the data unit via the new side-link communication link, and controls the transmitter circuit to transmit an indication of a cell identifier of a cell formed by the wireless network infrastructure device and an identifier of the first relay communication device that can be used by the wireless communication network to recover any of the lost data units. **Claim 38** A communication device for transmitting data to a wireless communication network or receiving data from a wireless communication network, a transceiver circuit configured to transmit a signal to or receive a signal from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device, Control the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a plurality of direct communication links with the wireless network infrastructure device and a plurality of indirect communication links via a plurality of relay communication devices that provide a direct communication link to the wireless network infrastructure device and each include a sidelink communication link with the communication device. Include a controller circuit configured to transmit a data unit to the wireless network infrastructure device using the multi-path communication or receive a data unit from the wireless network infrastructure device using the multi-path communication. The controller circuit Determine that at least one link quality of the plurality of indirect communication links can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device, or Determine that at least one link quality of the plurality of direct communication links can no longer support communication of the data unit due to transmission of the data unit to the wireless network infrastructure device or reception of the data unit from the wireless network infrastructure device. Identify at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links, and Control the transceiver circuit to transmit an indication that communication of the data unit can no longer be supported via at least one survivor of at least one of the plurality of indirect communication links or at least one of the plurality of direct communication links, and If the at least one surviving communication link is an indirect communication link, control the transceiver circuit to transmit a cell identifier of a cell formed by the wireless network infrastructure device and an identifier of the relay communication device forming the indirect communication link that can be used by the wireless communication network to recover any of the lost data units. When the at least one surviving communication link is a direct communication link, the communication device is configured to transmit a cell identifier of a cell formed by the wireless network infrastructure device that forms the direct communication link, which can be used by the wireless communication network to control the transceiver circuit to recover any of the lost data units.

39. A communication device for transmitting data to or receiving data from a wireless communication network, comprising: a transceiver circuit configured to transmit or receive signals to or from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device; controlling the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network, including a first direct communication link with the wireless network infrastructure device and an indirect communication link via a relay communication device including a second direct communication link with the wireless network infrastructure device and a side-link communication link with the relay communication device; using the multi-path communication to transmit a data unit to the wireless network infrastructure device or receive a data unit from the wireless network infrastructure device, and the side-link communication link with the relay communication device includes a controller circuit configured to be formed from a set grant resource of a side-link radio interface, and the controller circuit is determining that the link quality of the direct communication link can no longer support the communication of the data unit due to the transmission of the data unit to the wireless network infrastructure device or the reception of the data unit from the wireless network infrastructure device; executing a re-establishment procedure to re-establish the direct communication link with the wireless network infrastructure device. Control the transceiver circuit to transmit the data unit to the wireless network infrastructure device using the re-established direct communication link according to multi-path communication, or receive the data unit from the wireless network infrastructure device using the re-established direct communication link, and transmit the data unit to the wireless network infrastructure device using the set grant resources already established for the sidelink communication link, or receive the data unit from the wireless network infrastructure device using the set grant resources already established for the sidelink communication link, and is configured to be a communication device.

40. A communication device for transmitting data to a wireless communication network or receiving data from a wireless communication network, A transceiver circuit configured to transmit or receive signals to or from one or more wireless network infrastructure devices of the wireless communication network or another communication device functioning as a relay communication device; Control the transceiver circuit to establish multi-path communication with the wireless network infrastructure device of the wireless communication network including a first direct communication link with the wireless network infrastructure device and a second direct communication link provided to the wireless network infrastructure device, and an indirect communication link via a relay communication device including a sidelink communication link with the relay communication device, Including a controller circuit configured to control the transceiver unit to transmit a data unit to the wireless network infrastructure device or receive a data unit from the wireless network infrastructure device using the multi-path communication, and the controller circuit Using the indirect communication link and the direct communication link, determine that the data unit of the uplink cannot be simultaneously transmitted to the wireless network infrastructure device, Give priority to the transmission of the uplink data unit by selecting either the indirect communication link or the direct communication link via the sidelink communication link, and A communication device configured to control the transceiver circuit to transmit a data unit to a wireless network infrastructure device using the multi-path communication by transmitting the data unit to the wireless network infrastructure device using either the selected sidelink communication link or the selected direct communication link.

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