Multipath u2n link failure report

Abstract

A remote terminal configured with a non-split SRB1 transmits an uplink (UL) PC5-RRC message with an encapsulated failure report to a relay terminal providing the relay communication link during U2N multipath operation between the network and the remote terminal device. The failure report is generated and the PC5-RRC message is sent in response to the remote terminal determining that the direct communication link to the network has experienced an RLF. The relay terminal, using its own SRB1 configuration, sends an uplink (UL) RRC message to the network where the UL RRC message includes the encapsulated failure report. The relay terminal receives a downlink (DL) RRC message from the network where the DL RRC message includes information for reconfiguring the remote terminal. The relay terminal sends a downlink (DL) PC5-RRC message with the information to the remote terminal.

Description

MULTIPATH U2N LINK FAILURE REPORTCLAIM OF PRIORITY

[0001] The present application claims priority to Provisional Application No. 63 / 531 ,872, entitled “Failure Report Under Multipath U2N Relay”, docket number TPRO 00395 US, filed August 10, 2023, assigned to the assignee hereof and hereby expressly incorporated by reference in its entirety.FIELD

[0002] This invention generally relates to wireless communications and more particularly to failure reports for multipath with a U2N relay terminal.BACKGROUND

[0003] Many wireless communication systems that employ several base stations that provide wireless service to user equipment (UE) devices enable sidelink communication between two or more UE devices where the UE devices can communicate directly with other UE devices. In addition, one or more UE devices can be used as relay devices between a source UE device and a destination UE device where the relay devices forward data received from the source UE device to the destination UE device. Some conventional systems support multipath communication using a relay UE (relay terminal), where a remote UE device (remote terminal) is connected to the network via direct communication link (direct path) and a relay communication link (indirect path). Such techniques have the potential to improve the reliability / robustness as well as throughput of communications. In some situations, the remote terminal initially connects to a base station via the indirect path since the remote terminal may be out-of- coverage (OoC). When the remote terminal moves in-coverage, it may additionally connect to the base station via the direct path, while keeping the indirect path for better robustness. When one path fails, with multipath techniques, the other path may work sufficiently well to maintain communication between the remote terminal and thenetwork. In particular, if the direct path experiences RLF (Radio Link Failure) the indirect path may be kept to maintain ongoing communication.SUMMARY

[0004] A remote terminal configured with a non-split SRB1 transmits an uplink (UL) PC5-RRC message with an encapsulated failure report to a relay terminal providing the relay communication link during U2N multipath operation between the network and the remote terminal device. The failure report is generated and the PC5-RRC message is sent in response to the remote terminal determining that the direct communication link to the network has experienced an RLF. The relay terminal, using its own SRB1 configuration, sends an uplink (UL) RRC message to the network where the UL RRC message includes the encapsulated failure report. The relay terminal receives a downlink (DL) RRC message from the network where the DL RRC message includes information for reconfiguring the remote terminal. The relay terminal sends a downlink (DL) PC5-RRC message with the information to the remote terminal.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 A is a block diagram of a system for an example of direct link failure reporting for a remote terminal device during U2N multipath operation between a network and the remote terminal device where the remote terminal device is configured with non-split SRB1.

[0006] FIG. 1 B is a block diagram of the system for an example of terminal reconfiguration in response to the failure report.

[0007] FIG. 1 C is a block diagram of the system for an example of failure reporting where a remote terminal serving cell provides the direct communication link and a relay terminal serving cell provides the indirect communication link.

[0008] FIG. 1 D is a block diagram of the system for an example of terminal reconfiguration in response to the failure report where a remote terminal serving cellprovides the direct communication link and a relay terminal serving cell provides the indirect communication link.

[0009] FIG. 1 E is a block diagram of the system for an example of failure reporting where the remote terminal serving cell and the relay terminal serving cell are provided by different network nodes (e.g., different gNBs).

[0010] FIG. 1 F is a block diagram of the system for an example of terminal reconfiguration in response to the failure report where the remote terminal serving cell is provided by the first network node and the relay terminal serving cell is provided by the second network node.

[0011] FIG. 2 is a block diagram of an example of a base station suitable for use as the network node.

[0012] FIG. 3 is a block diagram of an example of a UE device suitable for use as each of the terminal devices.

[0013] FIG. 4 is a block diagram of an example of a UL PC5-RRC message suitable for use as the UL PC5-RRC message.

[0014] FIG. 5 is a block diagram of an example of a UL RRC message suitable for use as the UL RRC message.

[0015] FIG. 6 is a block diagram of an example of a DL RRC message suitable for use as the DL RRC message.

[0016] FIG. 7 is a flow chart of an example of a method of multipath U2N link failure reporting.

[0017] FIG. 8 is a flow chart of an example of method of multipath U2N link failure reporting from a remote terminal device over a relay communication link.DETAILED DESCRIPTION

[0018] As discussed above, the indirect path may be maintained when the direct path suffers an RLF. In order to ensure proper control from the network, it is desirable for the remote terminal (remote user equipment (UE)) to provide a failure report to thenetwork. For the case when the direct path fails, a failure report may be sent to the network via the relay terminal (relay UE). An example of the direct path failure report in conventional systems is the MCGFailurelnformation which is a Radio Resource Control (RRC) message.

[0019] The base station (gNB) of the network configures the remote terminal with a Signaling Radio Bearer 1 (SRB1 ) which is used to transmit RRC messages from the remote terminal. For conventional systems, the SRB1 configuration may be 1 ) a nonsplit SRB1 where the remote terminal can only send RRC message to the network over the direct path, 2) a split SRB1 where the remote terminal can send RRC messages to the network over either the direct path or the indirect path, and 3) split SRB1 with duplication where the remote terminal is instructed to send RRC messages to the network over both the direct path and the indirect path.

[0020] Where the direct path experiences an RLF, a failure report is reported through the PC5-RRC connected relay terminal. In conventional systems, however, the failure report can only be reported through the indirect path with split SRB1 configurations. An RRC message is delivered to the network via the PC5-RRC connected relay terminal, but the content of the message is transparent to the relay terminal. More specifically, the RRC message is mapped to the Sidelink Radio Link Control 1 (SL-RLC1 ) in the Sidelink Relay Adaptation Protocol (SRAP) in the sidelink. The relay terminal further maps this to the corresponding RLC channel for the Uu link.

[0021] In conventional systems, therefore, the remote terminal is not be able to send the direct path failure report over the indirect path if configured with non-split SRB1 . In this situation, the remote terminal must declare RLF and attempt to reestablish an RRC connection to the network even though the indirect path is still useable. In accordance with the techniques discussed herein, however, a failure report can be provided from a non-split SRB1 configured remote terminal via the relay terminal.

[0022] As discussed below, a remote terminal configured with a non-split SRB1 transmits an uplink (UL) PC5-RRC message with an encapsulated failure report to the relay terminal providing the relay communication link during U2N multipath operation between the network and the remote terminal device. The failure report is generated and the PC5-RRC message is sent in response to the remote terminal determining thatthe direct communication link to the network has experienced an RLF. The relay terminal, using its own SRB1 configuration, sends an uplink (UL) RRC message to the network where the UL RRC message includes the encapsulated failure report. The relay terminal receives a downlink (DL) RRC message from the network where the DL RRC message includes information for reconfiguring the remote terminal. The relay terminal sends a downlink (DL) PC5-RRC message with the information to the remote terminal.

[0023] In general, a network node such as a gNB can have multiple cells, whereby the cells may support the same or different portion of the gNB coverage. Additionally, the cells may operate in different frequencies. The indirect communication link and the direct communication link may be through the same cell of a single network node (gNB), may be through two different cells of the same network node, or may be through two different cells where each cell is provided by a different network node. Where the cells providing the direct communication link and the indirect communication link are different, information is routed between the remote terminal and the cell providing the direct path based on entity identification information. A communication interface, such as the Xn interface or via Inter-Node Message (INM) which is used to send RRC message across various difference NW interfaces, is used where the cells are provided by different network nodes. For the examples discussed herein, the UL PC5-RRC message and the UL RRC message include a cell identifier and a remote terminal identifier. Also, the DL RRC message includes the remote terminal identifier, allowing the relay terminal to transmit the DL PC5-RRC message to the appropriate terminal device.

[0024] FIG. 1 A is a block diagram of a system 100 for an example of direct link failure reporting for a remote terminal device 102 during U2N multipath operation between a network 104 and the remote terminal device 102 where the remote terminal device 102 is configured with non-split SRB1. For the example, the remote terminal device 102 is connected through a direct communication link 106 to a cell provided by a network node in the network 104 and is also connected through an indirect communication link (relay communication link) 108 via a relay terminal device 110 to a cell provided by a network node in the network 104. As discussed above and in the examples below, a single cell may facilitate both links 106, 108 or different cells mayfacilitate the two links 106, 108, where both cells may be provided by a single network node or each of the two cells is provided by a different network node.

[0025] A network node is any apparatus, equipment, device, or combination of devices, on the network side of the communication system that is connected to the communication network or is part of communication network. Some examples of a network node include a base station, a node B, an E-UTRA Node B, Evolved Node B, eNodeB, eNB, a New Generation eNB (ng-eNB), a gNodeB (also known as a gNB) in new radio (NR) technology, a macro station, pico station, and a femto station. The network node may form, or be a part of, the radio access network (RAN) that provides a connection between the core network and terminal communication devices. A RAN may be organized into three functional blocks including a Radio Unit (RU), a Distributed Unit (DU) and a Centralized Unit (CU). The RU transmits, receives, amplifies, and digitizes radio frequency signals and typically located near, or integrated into, the antenna. The DU and CU perform computations and / or processing to send and receive digitalized radio signals to and from the core network. The DU is typically located at or near the RU and the CU may be closer to the core network. The infrastructure or connection between the RU and the DU is often referred to as fronthaul and the infrastructure or connection between the DU and the CU is often referred to as a midhaul. The communication node, therefore, may perform the functions of one or more of the RU, DU and / or CU depending on the particular implementation.

[0026] A terminal communication device, such as the remote terminal device 102 and the relay terminal device 110, is a communication device on the terminal side of the communication system and is sometimes referred to as user equipment (UE), a UE device, a terminal device, wireless mobile device, wireless communication device and other terms. Some examples of a terminal communication device include a mobile phone, a smart phone, a personal digital assistant (PDA), tablet, and laptop computer. In some situations, the terminal communication device is a machine type communication (MTC) communication device or Internet-of-Things (IOT) device. In addition, the terminal communication device may be, or may be a part of, a wearable device or a vehicle where the vehicle may be terrestrial vehicle, watercraft, or aircraft(including unmanned aerial vehicles). The terminal communication device, therefore, is any fixed, mobile, or portable equipment that performs the functions of the terminal device described herein.

[0027] During U2N multipath operation, the remote terminal device 102 determines that the direct communication link 106 has experienced an RLF 112 and, in response, generates a direct radio link failure report 114 for transmission to the network 104 over the indirect communication link 108. The remote terminal device 102 generates and transmits a UL direct communications interface (PC5) radio resource control (RRC) message (UL PC5-RRC message) 116 including an encapsulated version of the direct radio link failure report 114. The relay terminal device 110 receives the UL PC5-RRC message 116 with the failure report 114 over the PC5 connection and generates a UL RRC message 118 that includes the encapsulated failure report 114. The relay terminal device 110 is configured with an SRB1 (relay terminal SRB1 ) different from the non-split SRB1 configuration (remote terminal SRB1 ) of the remote terminal device 102. Using the relay terminal SRB1 , the relay terminal device transmits the UL RRC message 118 with the encapsulated failure report 114 to the network 104. Where the relay serving cell is different from the remote terminal direct link serving cell, the information in the UL RRC message is forwarded to the remote terminal direct link serving cell. As discussed below in further detail, the UL PC5-RRC message 116 and the UL RRC message 118 each include a remote terminal identifier and a cell identifier of the remote terminal direct link serving cell for the examples herein. The failure report 114 includes a sidelink quality indicator in the examples. An example of suitable indicator is a Sidelink Reference Signal Received Power (SL-RSRP) measurement of the sidelink communication link between one or more candidate relay terminals and the remote terminal 102. The sidelink quality measurement may also include a measurement of the PC5 link between the relay terminal 110 and the remote terminal device 102. In some situations, the failure report 114 may also include RSRP measurements for nearby cells.

[0028] FIG. 1 B is a block diagram of the system 100 for an example of terminal reconfiguration in response to the failure report 114. After receiving the failure report information, the remote terminal direct link serving cell determines a preferred action forthe remote terminal device 102. An example of a preferred action includes reconfiguring the remote terminal device 102 with a single path where the single path may include the current indirect communication link 108 or may be a new indirect path including another relay terminal device. Another example includes reconfiguring the remote terminal device 102 with a new direct communication link to a new cell (e.g., handover). After the handover is complete, the remote terminal device may establish a U2N multipath connection with the addition of an indirect communication link. In another example, the direct link serving cell may reconfigure the remote terminal device with split SRB1. Where available indirect paths have poor quality or no alternative paths are available, the preferred action may include sending the remote terminal device to RRCJDLE or RRCJNACTIVE. For example, where the SL-RSRP measurements included in the failure report indicates that the available indirect paths have a channel quality below a threshold, the direct link serving cell may send an RRC Release message to transition the remote terminal device to IDLE or INACTIVE.

[0029] The remote terminal direct link serving cell generates a dedicated control channel (DCCH) message 120 for reconfiguring the remote terminal device 102. The network 104 transmits a DL RRC message 122 including an encapsulated version of the DCCH message 120. In addition to the DCCH message 120, the DL RRC message includes a device identifier of the remote terminal device 102. The relay terminal device 110 receives the DL RRC message 122 and transmits a DL PC5-RRC message to the remote terminal device 102 that includes the DCCH message 120.

[0030] FIG. 1 C is a block diagram of the system 100 for an example of failure reporting where a remote terminal serving cell 126 provides the direct communication link 106 and a relay terminal serving cell 128 provides the indirect communication link 108. The remote terminal device 102 and the relay terminal device 110 transmit and receive the messages and otherwise operate as discussed above. For the example of FIG. 1 C, a single network node (e.g., gNB) 130 provides both the remote terminal serving cell 126 and the relay terminal serving cell 128 where failure report information 132 is forwarded by the relay terminal cell 128 to the remote terminal serving cell 126. The failure report information 132 is at least based on the failure report 114 and, insome situations is the failure report 114. For the example, the INM from the relay terminal serving cell 128 to the remote terminal serving cell 126 indicates the purpose of the messaging and the UE ID of the remote terminal device 102. In some cases, the UE ID may be the C-RNTI and, in other cases, it may be the L2ID. For the example of FIG. 1 C, therefore, the failure report 114 is forwarded over the communication link to the relay terminal serving cell 128 even though it is likely that a communication link to the remote terminal serving cell 126 is available.

[0031] FIG. 1 D is a block diagram of the system 100 for an example of terminal reconfiguration in response to the failure report 114 where a remote terminal serving cell 126 provides the direct communication link 106 and a relay terminal serving cell 128 provides the indirect communication link 108. The remote terminal device 102 and the relay terminal device 110 transmit and receive the messages and otherwise operate as discussed above. For the example of FIG. 1 D, the single network node (e.g., gNB) 130 provides both the remote terminal serving cell 126 and the relay terminal serving cell 128 where reconfiguration information 134 is forwarded by the remote terminal serving cell 126 to the relay terminal serving cell 128. The failure report information 134 contains the information in the DCCH message 120 and, for the example, is the DCCH message 120. The relay terminal serving cell 128 sends the encapsulated DCCH message toward the remote terminal device 102 via the relay terminal device 110.

[0032] FIG. 1 E is a block diagram of the system 100 for an example of failure reporting where the remote terminal serving cell 126 and the relay terminal serving cell 128 are provided by different network nodes (e.g., different gNBs) 136, 138. The remote terminal serving cell 126 of a first network node 136 provides the direct communication link 106 and a relay terminal serving cell 128 of a second network node 138 provides the indirect communication link 108. The remote terminal device 102 and the relay terminal device 110 transmit and receive the messages and otherwise operate as discussed above. For the example of FIG. 1 E, where the failure report 114 is forwarded by the relay terminal cell 128 to the remote terminal serving cell 126 over an Xn interface 140. In some situations, failure report information based on the failure report 114 is forwarded rather than the failure report 114 as received by the relay terminalserving cell 128. For the example, the Xn from the relay terminal serving cell 128 to the remote terminal serving cell 126 indicates the purpose of the messaging and the UE ID of the remote terminal device 102. In some cases, the UE ID may be the C-RNTI and, in other cases, it may be the L2ID.

[0033] FIG. 1 F is a block diagram of the system 100 for an example of terminal reconfiguration in response to the failure report 114 where the remote terminal serving cell 126 is provided by the first network node 136 and the relay terminal serving cell 128 is provided by the second network node 138. The remote terminal serving cell 126 provides the direct communication link 106 and the relay terminal serving cell 128 provides the indirect communication link 108. The remote terminal device 102 and the relay terminal device 110 transmit and receive the messages and otherwise operate as discussed above. For the example of FIG. 1 F, a message 142 including the DCCH message 120 is sent from the remote terminal serving cell 126 to the relay terminal serving cell 128 over the Xn interface 140. The message 142 includes a terminal identifier identifying the remote terminal device 102. The relay terminal serving cell 128 transmits the DL RRC message with the DCCH 120 and the terminal identifier to the relay terminal device 110. For the example, the network node 136 indicates, in an XnAP message, the purpose of the message delivery which triggers the relay terminal serving cell 128 in the network node 138 to send the DL RRC message with the DCCH 120 towards the remote terminal device 102.

[0034] FIG. 2 is a block diagram of an example of a base station 200 suitable for use as a network node 130, 136, 138. The base station 200 includes electronics 204, transmitter 206, a receiver 208, and multiple antennas 210, as well as other electronics, hardware, and code. The base station 200 is any fixed, mobile, or portable equipment that performs the functions described herein. The various functions and operations of the blocks described with reference to the base station 200 and network node 102 may be implemented in any number of devices, circuits, or elements. Two or more of the functional blocks may be integrated in a single device, and the functions described as performed in any single device may be implemented over several devices. The base station 200 may be a fixed device or apparatus that is installed at a particular location atthe time of system deployment. Examples of such equipment include fixed base stations or fixed transceiver stations. Although the base station may be referred to by different terms, the base station is typically referred to as a gNodeB or gNB when operating in accordance with one or more communication specifications of the 3GPP V2X operation. In some situations, the base station 200 may be mobile equipment that is temporarily installed at a particular location. Some examples of such equipment include mobile transceiver stations that may include power generating equipment such as electric generators, solar panels, and / or batteries. Larger and heavier versions of such equipment may be transported by trailer. In still other situations, the base station 200 may be a portable device that is not fixed to any particular location.

[0035] The electronics 204 include any combination of hardware, software, and / or firmware for communicating with and controlling other base station components to execute the functions described herein as well as facilitating the overall functionality of the base station 200. The electronics 204, therefore, cooperatively operate with other base station 200 components to initiate tasks and perform the operations and functions of the base station 200. An example of suitable electronics 204 includes code running on a microprocessor or processor arrangement connected to memory. The transmitter 206 includes electronics configured to transmit wireless signals. In some situations, the transmitter 206 may include multiple transmitters. The receiver 208 includes electronics configured to receive wireless signals. In some situations, the receiver 208 may include multiple receivers. The receiver 208 may receive signals through multiple antennas 210 or through a selected antenna of the plurality of antennas 210. The antennas 210 may include separate transmit and receive antennas.

[0036] The transmitter 206 and receiver 208 in the example of FIG. 2 perform radio frequency (RF) processing including modulation and demodulation. The receiver 208, therefore, may include components such as low noise amplifiers (LNAs) and filters. The transmitter 206 may include filters and amplifiers. Other components may include isolators, matching circuits, and other RF components. These components in combination or cooperation with other components perform the base station functions. The required components may depend on the particular functionality required by the base station 200.

[0037] The transmitter 206 includes a modulator (not shown), and the receiver 208 includes a demodulator (not shown). The modulator modulates the signals to be transmitted as part of the downlink signals and can apply any one of a plurality of modulation orders. The demodulator demodulates any uplink signals received at the base station 200 in accordance with one of a plurality of modulation orders. The electronics 204 in conjunction with the transmitter 206 apply a precoder matrix to signals transmitted through the multiple antennas 210.

[0038] The base station 200 includes a communication interface 212 for communicating with other base stations and other network components, and other entities, such as servers and databases. The communication interface 212 may be connected to a backhaul or network enabling communication with other base stations. In some situations, the link between base stations may include at least some wireless portions. The communication interface 212, therefore, may include wireless communication functionality and may utilize some of the components of the transmitter 206 and / or receiver 208.

[0039] The electronics 204, in conjunction with the receiver 208, measure and evaluate signals transmitted by UE devices. The electronics 204 and the receiver 206, therefore, can receive, measure, and evaluate uplink signals including reference signals transmitted by UE devices. Signal measurements and evaluations can be stored in a memory 214 and are used to determine the location of UE devices in some circumstances.

[0040] The electronics 204, in conjunction with the transmitter 206 and antennas 210, process outgoing signals to precode signals transmitted to UE devices. Accordingly, the electronics 204 and transmitter 206 apply the appropriate MU-MIMO precoder to signals transmitted to a specific UE device.

[0041] FIG. 3 is a block diagram of an example of a UE device 300 suitable for use as each of the terminal devices 102, 110. In some examples, the UE device 300 is any wireless communication device such as a mobile phone, a transceiver modem, a personal digital assistant (PDA), a tablet, or a smartphone. In other examples, the UE device 300 is a machine type communication (MTC) communication device or Internet-of-Things (IOT) device. The UE device 300, therefore is any fixed, mobile, or portable equipment that performs the functions described herein. The various functions and operations of the blocks described with reference to UE device 300 may be implemented in any number of devices, circuits, or elements. Two or more of the functional blocks may be integrated in a single device, and the functions described as performed in any single device may be implemented over several devices.

[0042] The UE device 300 includes at least electronics 302, a transmitter 304 and a receiver 306. The electronics 302 include any combination of hardware, software, and / or firmware for communicating with and controlling other UE device components to execute the functions described herein as well as facilitating the overall functionality of a communication device. The electronics 302, therefore, cooperatively operate with other UE device components to initiate tasks and perform the operations and functions of the UE device 300. An example of suitable electronics 302 includes code running on a microprocessor or processor arrangement connected to memory 310. The transmitter 304 includes electronics configured to transmit wireless signals. In some situations, the transmitter 304 may include multiple transmitters. The receiver 306 includes electronics configured to receive wireless signals. In some situations, the receiver 306 may include multiple receivers. The receiver 306 and transmitter 304 receive and transmit signals, respectively, through antenna 308. The antenna 308 may include separate transmit and receive antennas. In some circumstances, the antenna 308 may include multiple transmit and receive antennas.

[0043] The transmitter 304 and receiver 306 in the example of FIG. 3 perform radio frequency (RF) processing including modulation and demodulation. The receiver 306, therefore, may include components such as low noise amplifiers (LNAs) and filters. The transmitter 304 may include filters and amplifiers. Other components may include isolators, matching circuits, and other RF components. These components in combination or cooperation with other components perform the communication device functions. The required components may depend on the particular functionality required by the communication device.

[0044] The transmitter 304 includes a modulator (not shown), and the receiver 306 includes a demodulator (not shown). The modulator can apply any one of a plurality ofmodulation orders to modulate the signals to be transmitted as part of the uplink signals. The demodulator demodulates the downlink signals in accordance with one of a plurality of modulation orders.

[0045] The UE device 300 is capable of transmitting and receiving sidelink signals to and from other UE devices as well as communicating with base stations. The electronics 302, in conjunction with the receiver 306, measure an evaluate signals transmitted by other devices, such as base stations and UE devices. The electronics 302 and the receiver 306, therefore, can receive, measure, and evaluate downlink reference signals transmitted by a base station. Signal measurements and evaluations can be stored in the memory 310. The electronics 302 and receiver 306 can also receive, measure and evaluate discovery signals transmitted by nearby UE devices to generate a neighbor list that includes neighbor UE devices within the maximum distance. The neighbor list is stored in the memory 310 and may be transmitted to a base station.

[0046] FIG. 4 is a block diagram of an example of a UL PC5-RRC message 400 suitable for use as the UL PC5-RRC message 116. The UL PC5-RRC message 400 includes the direct path failure report 114, a cell identifier 402 and remote terminal identifier 404. In addition to indicating that the direct communication link 106 has experienced an RLF 112, the failure report 114 includes one or more sidelink quality measurements 406. The remote terminal identifier 404 may be any type of UE ID that identifies the remote terminal device 102. For the example, the remote terminal identifier 404 is the Cell Radio Network Temporary Identifier (C-RNTI) of the remote terminal device 102. In some situations, remote terminal identifier 404 may be the local ID (generated by the gNB for SRAP). Another example of a suitable remote terminal identifier 404 is the L2ID from the application layer. The cell identifier 402 is any cell ID that identifies the remote terminal serving cell 126 that is the serving cell of the remote terminal device 102. An example of a suitable cell identifier 402 is the New Radio (NR) Cell Global Identity (NCGI). The NCGI is a combination of the PLMN Identifier (PLMN- ID) and the 36-bit NR Cell Identity (NCI). Ini some situations, the cell identifier 402 may be the Physical Cell ID (PCI). For the example of FIG. 4, the cell identifier 402 and theremote terminal identifier 404 are part of the PC5-RRC message 400 outside of the encapsulated contents of the failure report 114). In some situations, the cell identifier 402 and the remote terminal identifier 404 may be included within the encapsulated failure report 114. The PC5-RRC message 400 may also include RSRP measurements of cells provided by one or more network nodes.

[0047] The SL quality measurements 406 may be any measurements taken by the remote terminal device 102 that indicate a quality of a link to candidate relay terminals. For the example, the SL quality measurements 406 are SL-RSRP measurements that include measurements of sidelinks to candidate relay terminal devices and to the relay terminal device 110.

[0048] FIG. 5 is a block diagram of an example of a UL RRC message 500 suitable for use as the UL RRC message 118. The UL RRC message 500 includes the direct path failure report 114, the cell identifier 402 and the remote terminal identifier 404.

[0049] FIG. 6 is a block diagram of an example of a DL RRC message 600 suitable for use as the DL RRC message 122. The DL RRC message 600 includes the remote terminal identifier 404 and the DCCH 120.

[0050] FIG. 7 is a flow chart of method of multipath U2N link failure reporting. The method may be performed in a system such the system 100 discussed herein. For the example, the method is performed by a relay terminal device such as the relay terminal device 110. The method may be performed using any of several techniques involving any combination of software, hardware, and firmware. For example, software code running on electronics including a processor, computer or other processor arrangement within the network node may facilitate the generation, formatting, reception and transmission of signals and messages. One or more of the steps may be omitted, combined, performed in parallel, or performed in a different order than that described herein or shown in FIG. 7. In still further examples, additional steps may be added that are not explicitly described in connection with the example discussed with reference to FIG. 7.

[0051] At step 702, the relay terminal device provides a relay communication link between a remote terminal device and a relay serving cell of a network during U2N multipath operation between the network and the remote terminal device.

[0052] At step 704, an uplink (UL) direct communications interface (PC5) radio resource control (RRC) message (UL PC5-RRC message) is received from the remote terminal device. The relay terminal device 110 receives the UL PC5-RRC message 116 that comprises an encapsulated direct radio link failure report 114 generated by the remote terminal device 102 in response to the remote terminal device 102 detecting a radio link failure (RLF) of a direct path communication link 106 from the remote terminal device 102 to a remote terminal serving cell of the network. For the example, the remote terminal device 102 is configured with a remote terminal Signaling Radio Bearer 1 (SRB1 ) configuration being a non-split SRB1 configuration and the relay terminal device 110 is configured with a relay terminal SRB1.

[0053] At step 706, an uplink (UL) RRC message 118 is transmitted to the relay serving cell of the network 104. Using the relay terminal SRB1 configured to the relay terminal device 110, the relay terminal device transmits the UL RRC message 118 that comprises the encapsulated direct radio link failure report 114. The relay serving cell may the remote terminal serving cell or may be a different cell as discussed above.

[0054] At step 708, a downlink (DL) RRC message 122 is received from the relay serving cell of the network. The relay terminal device receives the DL RRC message 122 which includes an encapsulated Dedicated Control Channel (DCCH) message 120. For the example, the DL RRC message includes the remote terminal identifier identifying the remote terminal device 102.

[0055] At step 710, a DL PC5-RRC message 124 comprising the DCCH message 120 is transmitted to the remote terminal device 102.

[0056] FIG. 8 is a flow chart of an example of method of multipath U2N link failure reporting from a remote terminal device over a relay communication link. The method may be performed in a system such the system 100 discussed herein. For the example, the method is performed by a remote terminal device such as the remote terminal device 102. The method may be performed using any of several techniques involvingany combination of software, hardware, and firmware. For example, software code running on electronics including a processor, computer or other processor arrangement within the remote terminal device may facilitate the reception of signals, measurements, and transmissions. One or more of the steps may be omitted, combined, performed in parallel, or performed in a different order than that described herein or shown in FIG. 8. In still further examples, additional steps may be added that are not explicitly described in connection with the example discussed with reference to FIG. 8.

[0057] At step 802, the remote terminal device 102 communicates with a network 104 over a U2N multipath connection with a non-split Signaling Radio Bearer 1 (SRB1 ) configuration. The U2N multipath connection comprises a relay communication link 108 through a relay terminal device 110 and a direct communication link 106.

[0058] At step 804, it is determined that the direct communication link 106 has experienced a radio link failure (RLF). The remote terminal device 102 detects the RLF on the direct communication link 106 to the network 104.

[0059] At step 806, a UL PC5-RRC message 116 is transmitted to the relay terminal device 110. The remote terminal device 102 transmits the UE PC5-RRC message 116 that includes an encapsulated direct radio link failure report 114 generated in response to determining the direct path communication link 106 has experienced the RLF 112.The UL PC5-RRC message 116 includes a cell identifier 402 identifying the serving cell of the remote terminal device 102 and a remote terminal identifier 404 identifying the remote terminal device 102.

[0060] At step 808, a downlink (DL) PC5-RRC message 124 comprising an encapsulated Dedicated Control Channel (DCCH) message 120 is received from the relay terminal device 110.

[0061] To clearly illustrate this interchangeability of hardware, firmware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware or software, or a combination of these techniques, depends upon the particular application and design constraints imposed on the overall system. The described functionality may be implemented in various ways for eachparticular application, but such implementation decisions do not cause a departure from the scope of the present disclosure. In accordance with various embodiments, a processor, device, component, circuit, structure, machine, module, etc. can be configured to perform one or more of the functions described herein. The term "configured to" or "configured for" as used herein with respect to a specified operation or function refers to processors, devices, components, circuits, electronics, and equipment that are physically constructed, programmed, instructed and / or arranged to perform the specified operation or function. Furthermore, the various illustrative logical blocks, modules, devices, components and circuits described herein can be implemented within or performed by an integrated circuit (IC) that can include a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), other electronics or combinations thereof. (ASIC), a field programmable gate array (FPGA) or other programmable logic device, or any combination thereof. The logical blocks, electronics, and circuits can further include antennas and / or transceivers to communicate with various components within the network or within the device. A general-purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, or state machine. A processor can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration to perform the functions described herein.

[0062] When implemented in software, the functions can be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein can be implemented as software stored on a computer- readable medium. Computer readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program or code from one place to another. A storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices,or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0063] Therefore, the methods and apparatus of this invention may take the form, at least partially, of program logic or program code (i.e., instructions) embodied in tangible media, such as a machine-readable storage medium. When the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. The methods and apparatus of the present invention may also be embodied in the form of program code that is transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via any other form of transmission. When the program code is received and loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. When implemented on a general-purpose processor, the program code combines with the processor to provide a unique apparatus that operates analogously to specific logic circuits.

[0064] Additionally, memory or other storage, as well as communication components, may be employed in embodiments of the present disclosure. It will be appreciated that, for clarity purposes, the above description has described embodiments of the present disclosure with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units, processing logic elements or domains may be used without detracting from the present disclosure. For example, functionality illustrated to be performed by separate processing logic elements, or controllers, may be performed by the same processing logic element, or controller. Therefore, references to specific functional units are only references to a suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

[0065] Clearly, other embodiments and modifications of this invention will occur readily to those of ordinary skill in the art in view of these teachings. The above description is illustrative and not restrictive. This invention is to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings. The scope of the invention should, therefore, be determined not with reference to the above description,but instead should be determined with reference to the appended claims along with their full scope of equivalents.

Claims

CLAIMS1 . A method comprising: providing, by a relay terminal device, a relay communication link between a remote terminal device and a relay serving cell of a network during U2N multipath operation between the network and the remote terminal device; receiving, from the remote terminal device, an uplink (UL) direct communications interface (PC5) radio resource control (RRC) message (UL PC5-RRC message) comprising an encapsulated direct radio link failure report generated by the remote terminal device in response to the remote terminal device detecting a radio link failure of a direct path communication link from the remote terminal device to a remote terminal serving cell of the network, the remote terminal device configured with a remote terminal Signaling Radio Bearer 1 (SRB1 ) configuration being a non-split SRB1 configuration and the relay terminal device configured with a relay terminal SRB1 ; and transmitting, using the relay terminal SRB1 , an uplink (UL) RRC message to the relay serving cell of the network, the UL RRC message comprising the encapsulated direct radio link failure report.

2. The method of claim 1 , further comprising: receiving, from the relay serving cell of the network, a downlink (DL) RRC message comprising an encapsulated Dedicated Control Channel (DCCH) message; and transmitting, to the remote terminal device, a DL PC5-RRC message comprising the DCCH message.

3. The method of clam 1 , wherein the relay serving cell and the remote terminal serving cell are the same cell.

4. The method of claim 1 , wherein the relay serving cell is first cell of a network node of the network and the remote terminal serving cell is a second cell of the network node of the network.

5. The method of claim 1 , wherein the relay serving cell is a first cell of a first network node of the network and the remote terminal serving cell is a second cell of a second network node of the network.

6. The method of claim 1 , wherein the UL RRC message comprises a remote terminal device identifier identifying the remote terminal device.

7. The method of claim 6, wherein the remote terminal device identifier is one of a Cell Radio Network Temporary Identifier (C-RNTI), a Sidelink Relay Adaptation Protocol (SRAP) local ID, or an application layer L2ID.

8. The method of claim 1 , wherein the UL RRC message comprises a cell identifier identifying the direct path serving cell.

9. The method of claim 7, wherein the cell identifier is one of a New Radio Cell Global Identifier (NCGI) or a Physical Cell ID (PCI).

10. The method of claim 8, wherein the first PC5-RRC message comprises the cell identifier.11 . The method of claim 2, wherein the DCCH message is one of an RRC Reconfiguration message or an RRC Release message for the remote terminal device.

12. The method of claim 2, wherein the DL RRC message comprises a remote terminal device identifier identifying the remote terminal device.

13. A relay terminal device comprising: a transceiver comprising a transmitter and a receiver, the transceiver configured to provide a relay communication link between a remote terminal device and a relay serving cell of a network during U2N multipath operation between the network and the remote terminal device;the receiver configured to receive, from the remote terminal device, an uplink (LIL) direct communications interface (PC5) radio resource control (RRC) message (UL PC5-RRC message) comprising an encapsulated direct radio link failure report generated by the remote terminal device in response to the remote terminal device detecting a radio link failure of a direct path communication link from the remote terminal device to a remote terminal serving cell of the network, the remote terminal device configured with a remote terminal Signaling Radio Bearer 1 (SRB1 ) configuration being a non-split SRB1 configuration and the relay terminal device configured with a relay terminal SRB1 , the transmitter configured to transmit, using the relay terminal SRB1 , an uplink (UL) RRC message to the relay serving cell of the network, the UL RRC message comprising the encapsulated direct radio link failure report.

14. The relay terminal device of claim 13, wherein: the receiver is further configured to receive, from the relay serving cell of the network, a downlink (DL) RRC message comprising an encapsulated Dedicated Control Channel (DCCH) message; and the transmitter is further configured to transmit, to the remote terminal device, a DL PC5-RRC message comprising the DCCH message.

15. The relay terminal device of claim 13, wherein the UL RRC message comprises a remote terminal device identifier identifying the remote terminal device.

16. The relay terminal device of claim 15, wherein the remote terminal device identifier is one of a Cell Radio Network Temporary Identifier (C-RNTI), a Sidelink Relay Adaptation Protocol (SRAP) local ID, or an application layer L2ID.

17. The relay terminal device of claim 13, wherein the UL RRC message comprises a cell identifier identifying the direct path serving cell.

18. The relay terminal device of claim 17, wherein the cell identifier is one of a New Radio Cell Global Identifier (NCGI) or a Physical Cell ID (PCI).

19. The relay terminal device of claim 18, wherein the UL PC5-RRC message comprises the cell identifier.

20. The relay terminal device of claim 13, wherein the DCCH message is one of an RRC Reconfiguration message or an RRC Release message for the remote terminal device.21 . A method comprising: communicating with a network over a U2N multipath connection with a non-split Signaling Radio Bearer 1 (SRB1 ) configuration, the U2N multipath connection comprising a relay communication link through a relay terminal device and a direct communication link; determining that the direct communication link has experienced a radio link failure (RLF); transmitting, to the relay terminal device, an uplink (UL) direct communications interface (PC5) radio resource control (RRC) message (UL PC5-RRC message) comprising an encapsulated direct radio link failure report generated in response to determining the direct path communication link has experienced the RLF.

22. The method of claim 21 , further comprising: receiving, from the relay terminal device, a downlink (DL) PC5-RRC message comprising an encapsulated Dedicated Control Channel (DCCH) message.

23. A non-transitory computer readable medium storing computer-executable instructions which when executed perform the method of: providing, by a relay terminal device, a relay communication link between a remote terminal device and a relay serving cell of a network during U2N multipath operation between the network and the remote terminal device;receiving, from the remote terminal device, an uplink (UL) direct communications interface (PC5) radio resource control (RRC) message (UL PC5-RRC message) comprising an encapsulated direct radio link failure report generated by the remote terminal device in response to the remote terminal device detecting a radio link failure of a direct path communication link from the remote terminal device to a remote terminal serving cell of the network, the remote terminal device configured with a remote terminal Signaling Radio Bearer 1 (SRB1 ) configuration being a non-split SRB1 configuration and the relay terminal device configured with a relay terminal SRB1 ; and transmitting, using the relay terminal SRB1 , an uplink (UL) RRC message to the relay serving cell of the network, the UL RRC message comprising the encapsulated direct radio link failure report.

24. The method of claim 11 , wherein the remote terminal device identifier is one of a Cell Radio Network Temporary Identifier (C-RNTI), a Sidelink Relay Adaptation Protocol (SRAP) local ID, or an application layer L2ID.

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