Multipath U2N relay failure reporting with link quality measurement

Abstract

The remote terminal device is connected to the network via a U2N multipath connection that includes a direct communication link to the network's direct link serving cell and an indirect communication link to the network via a relay terminal device. In response to determining that a radio link failure (RLF) has occurred on either the direct or indirect communication link, the remote terminal device sends a failure report that includes one or more sidelink quality measurements.

Description

Priority Claim

[0001] This application claims priority to U.S. Provisional Application No. 63 / 531872 (Docket No. TPRO 00395 US), entitled "Failure Report Under Multipath U2N Relay," filed on August 10, 2023, assigned to the assignee of this application, and incorporated herein by reference in its entirety.

Technical Field

[0002] The present invention generally relates to wireless communication, and more particularly, to failure reporting involving sidelink quality measurement for multipath connection using a U2N relay terminal.

Background Art

[0003] Many wireless communication systems employing multiple base stations to provide wireless services to user equipment (UE) devices enable sidelink communication between two or more UE devices, allowing them to communicate directly with each other. Furthermore, one or more UE devices can be used as relay devices between a source UE device and a destination UE device, where the relay device forwards data received from the source UE device to the destination UE device. Some conventional systems support multipath communication using relay UEs (relay terminals), where remote UE devices (remote terminals) connect to the network via direct communication links (direct paths) and relay communication links (indirect paths). Such techniques have the potential to improve not only communication throughput but also reliability / robustness. In some situations, a remote terminal may be out-of-coverage (OoC), so it initially connects to a base station via an indirect path. Once the remote terminal moves into coverage, it may also connect to a base station via a direct path while maintaining the indirect path for better robustness. In multipath technology, even if one path fails, another path may still function adequately to maintain communication between the remote terminal and the network. Specifically, even if a Radio Link Failure (RLF) occurs on the direct path, the indirect path may be maintained to preserve ongoing communication. [Overview of the project]

[0004] The remote terminal device is connected to the network via a U2N multipath connection that includes a direct communication link to the network's direct link serving cell and an indirect communication link to the network via a relay terminal device. Upon determining that a radio link failure (RLF) has occurred on either the direct or indirect communication link, the remote terminal device transmits a failure report that includes one or more sidelink quality measurements. [Brief explanation of the drawing]

[0005] [Figure 1A] This is a system block diagram illustrating an example of a link failure report from a remote terminal device during U2N multipath operation between the network and the remote terminal device. The link failure report sent to the network includes one or more link quality measurements.

[0006] [Figure 1B] This is a block diagram of a system that illustrates an example where an RLF occurs on an indirect communication link, and a remote terminal device sends a fault report, accompanied by link quality measurement, directly to the link serving cell on the direct communication link.

[0007] [Figure 1C] This is a system block diagram showing an example of terminal reconfiguration in response to a fault report received for an RLF of an indirect communication link.

[0008] [Figure 2] This block shows examples of base stations suitable for use as network nodes.

[0009] [Figure 3] This block diagram shows examples of UE devices suitable for use as terminal devices.

[0010] [Figure 4] This flowchart shows the method for reporting wireless link failures during multipath operation. [Modes for carrying out the invention]

[0011] As described above, all multipath U2N connections allow for the maintenance of either an indirect or direct path in the event of an RLF (Remote Resource Failure) in one path. To ensure proper control from the network, it is desirable for remote terminals (remote user equipment (UE)) to provide fault reports to the network. If a direct path fails, a fault report may be sent to the network via a relay terminal (relay UE). An example of direct path fault reporting in conventional systems is the Radio Resource Control (RRC) message, MCG Fault Information (MCGFailureInformation).

[0012] The network base station (gNB) configures a signaling radio bearer 1 (SRB1) at a remote terminal, which is used to transmit RRC messages from the remote terminal. The SRB is defined as a radio bearer (RB) used solely for transmitting RRC and NAS messages. According to one or more revisions of the 3GPP communication specification, SRB1 is defined for transmitting RRC messages in 5G New Radio (NR), as well as NAS messages, before the establishment of SRB2 using a dedicated control channel (DCCH) logical channel. In conventional systems, the configuration of SRB1 can be: 1) non-split SRB1, which allows the remote terminal to transmit RRC messages to the network only via a direct path; 2) split SRB1, which allows the remote terminal to transmit RRC messages to the network via either a direct or indirect path; and 3) split SRB1 with duplication, which instructs the remote terminal to transmit RRC messages to the network via both direct and indirect paths. In the case of non-split SRB1, SRB1 is configured only for the direct communication link.

[0013] If an RLF occurs on the direct path, the fault report is submitted via the relay terminal connected via PC5-RRC. However, in conventional systems, the fault report can only be submitted via the indirect path with a split SRB1 configuration. RRC messages are delivered to the network via the relay terminal connected via PC5-RRC, but the content of the message is transparent to the relay terminal. More specifically, in the sidelink, the RRC message is mapped to Sidelink Radio Link Control 1 (SL-RLC1) of the Sidelink Relay Adaptation Protocol (SRAP). The relay terminal further maps this to the corresponding RLC channel of the Uu link.

[0014] Therefore, in conventional systems, remote terminals cannot send failure reports for the direct path via the indirect path. In this situation, even though the indirect path is still available, the remote terminal must declare an RLF and attempt to re-establish the RRC connection to the network.

[0015] If an RLF occurs on an indirect path, the remote terminal device sends a fault report to a direct link serving cell in the network. In conventional systems, for example, a Master Cell Group (MCG) Fault Information (RRC message) is sent over the direct communication link. For the direct link serving cell to properly reconfigure the remote terminal device, it is useful for the serving cell to have link quality information about potential alternative communication links. According to the techniques discussed herein, a fault report is sent to the network, comprising one or more link quality measurements, including at least one sidelink quality measurement of the sidelink to the candidate relay terminal device. In some examples, any combination of quality link measurements for an alternative indirect communication link and an alternative direct communication link may be provided along with the quality link measurement of the current direct communication link. In some examples, the remote terminal device sends an RRC message to the direct link serving cell containing MCG fault information, including a sidelink reference signal received power (SL-RSRP) measurement of the SL communication link to the candidate relay terminal device and a direct link RSRP measurement to the alternative cell. In another example, a remote terminal device sends a UL PC5-RRC message containing a fault report, including link quality measurements, to a relay terminal device, and the relay terminal device sends a UL RRC message containing the fault report to the network. If the remote terminal device is configured with an undivided SRB1, the fault report is encapsulated in the UL PC5-RRC message and the UL RRC message. For example, a remote terminal configured with an undivided SRB1 may send an uplink (UL) PC5-RRC message containing an encapsulated fault report to a relay terminal providing a relay communication link during U2N multipath operation between the network and the remote terminal device. A fault report is generated and a PC5-RRC message is sent in response to the remote terminal determining that an RLF has occurred on the direct communication link to the network. The relay terminal device sends an uplink (UL) RRC message to the network using its own configured SRB1, where the UL RRC message contains the encapsulated fault report.The relay terminal receives a downlink (DL) RRC message from the network, which contains information for reconfiguring the remote terminal. The relay terminal then sends a downlink (DL) PC5-RRC message containing this information to the remote terminal.

[0016] The direct link serving cell reconfigures the remote terminal device at least partially based on link quality measurements, including at least one sidelink quality measurement. In some situations, the direct link serving cell may configure a new alternative indirect communication link via a candidate relay terminal device. In other situations, the direct link serving cell configures a new indirect communication link with a handover. Thus, service continuity is supported when an indirect path via a relay terminal device is involved. As part of the reconfiguration, the direct link serving cell may reconfigure the SRB1. For example, if the remote terminal device was originally configured with an undivided SRB1 and the remote terminal device reports an RLF on the direct link, the direct link serving cell may configure the remote terminal device with a divided SRB1. In some situations, the direct link serving cell may also transition the remote terminal device to RRC_IDLE or RRC_INACTIVE.

[0017] In general, a network node such as a gNB may have multiple cells, and these cells may support the same or different portions of the gNB coverage. Furthermore, these cells may operate at different frequencies. Indirect and direct communication links may circulate through the same cell of a single network node (gNB), through two different cells of the same network node, or through two different cells, each cell provided by a different network node. When the cells providing direct and indirect communication links are different, information is routed between the remote terminal and the cell providing the direct path based on entity identification information. When the cells are provided by different network nodes, a communication interface such as an Xn interface is used. In the examples discussed herein, UL PC5-RRC messages and UL RRC messages include a cell identifier and a remote terminal identifier. DL RRC messages also include a remote terminal identifier, which allows a relay terminal to send DL PC5-RRC messages to the appropriate terminal device.

[0018] Figure 1A is a block diagram of system 100 showing an example of a link failure report from a remote terminal device 102 during U2N multipath operation between network 104 and the remote terminal device 102. Here, the link failure report 106 sent to network 104 includes one or more link quality measurements 108. A network node 102 is any device, equipment, device, or combination of devices on the network side of a communication system that is connected to or part of a communication network. Some examples of network nodes include base stations, node B, E-UTRA node B, evolved node B, eNodeB, eNB, next-generation eNB (ng-eNB), gNodeB (also known as gNB) in New Radio (NR) technology, macro stations, pico stations, and femto stations. Network nodes may form or be part of a radio access network (RAN) that provides connectivity between the core network and terminal communication devices. A RAN may be organized into three functional blocks: radio units (RUs), distributed units (DUs), and centralized units (CUs). RUs transmit, receive, amplify, and digitize radio frequency signals and are typically located near or integrated into the antenna. DUs and CUs perform calculations and / or processing for sending and receiving digitized radio signals to and from the core network. DUs are typically located at or near the RU, while CUs may be located closer to the core network. The infrastructure or connectivity between the RU and DU is often called fronthaul, and the infrastructure or connectivity between the DU and CU is often called midhaul. Therefore, depending on the specific implementation, a communication node can perform one or more functions of an RU, DU, and / or CU.

[0019] A terminal communication device is a communication device on the terminal side of a communication system and may also be referred to as a user device (UE), UE device, terminal device, wireless mobile device, or wireless communication device. Some examples of terminal communication devices include mobile phones, smartphones, personal digital assistants (PDAs), tablets, and laptop computers. Depending on the context, a terminal communication device may be a machine-type communication (MTC) device or an Internet of Things (IoT) device. Furthermore, a terminal communication device may be a wearable device or a vehicle, or part thereof, where a vehicle may be a land vehicle, a ship, or an aircraft (including unmanned aerial vehicles). Thus, a terminal communication device is any fixed, mobile, or portable device that performs the functions of a terminal device as described herein.

[0020] In this example, the remote terminal device 102 is connected via a direct communication link 110 to a direct link serving cell 112 provided by a network node in network 104, and also via an indirect communication link (relay communication link) 114 to a cell provided by a network node (e.g., gNB) in network 104, through a relay terminal device 116. As discussed in the examples above and below, a single cell may facilitate both links 110, 114, or different cells may facilitate the two links 110, 114, where both cells are provided by a single network node, or each of the two cells is provided by a different network node. In the example in Figure 1A, the relay serving cell 117 is shown as a dashed box to show that the indirect communication path 114 may include a communication link to a relay serving cell 117 different from the direct link serving cell 112. When the direct link serving cell and the relay serving cell 117 are provided by different network nodes (e.g., gNB), the Xn interface between the two network nodes facilitates communication to the direct link serving cell 112.

[0021] During U2N multipath operation, the remote terminal device 102 determines that any of the communication links forming the U2N multipath connection has experienced a radio link failure (RLF), and in response, generates a radio link failure report 106 for transmission to the network 104 over a communication link that has not experienced the RLF. Thus, if an RLF occurs on the direct communication link 110, the remote terminal device 102 transmits the failure report 106 over the indirect communication link 114. If the remote terminal device is configured with split SRB1 or split SRB1 with duplication, the failure report is transmitted as a transparent RRC message to the relay terminal device using SRAP. If the remote terminal device is configured with non-split SRB1, the failure report is encapsulated and transmitted to the relay terminal device as a PC5-RRC message, and is relayed from the relay terminal device to the network as an UL RRC message using the SRB1 configuration of the relay terminal device.

[0022] The failure report 106 includes link quality measurements 108 of the communication link, which may include side links to candidate relay terminal devices, links to alternative cells, and currently active links to relay terminal devices and serving cells. For example, if an RLF is detected on the direct communication link 110, the link quality measurements 108 may include measurements of the side link 120 to the candidate relay terminal device 122, measurements of the side link 118 to the relay terminal device 116, and / or measurements of the link 124 to one or more alternative cells 126. The alternative cell 126 may be provided by the same network node (e.g., gNB) that provides the direct link serving cell 112, the same network node (e.g., gNB) that provides the serving cell to the relay terminal device 116, or another network different from both serving cells. In the examples herein, the link quality measurements 108 are reference signal received power (RSRP) measurements. Thus, the link quality measurements 108 of the link to the relay terminal device in this example are side link reference signal received power (SL-RSRP) measurements. However, the quality measurements 108 may be any type of measurement that indicates the quality of the link being measured.

[0023] In a non-split SRB1 configuration where an RLF occurs on the direct communication link, the remote terminal device 102 generates and transmits a UL Direct Communication Interface (PC5) Radio Resource Control (RRC) message (UL PC5-RRC message) containing an encapsulated version of the direct radio link failure report 106. The relay terminal device 116 receives the UL PC5-RRC message containing the failure report 106 on the PC5 connection and generates a UL RRC message containing the encapsulated failure report 106. The relay terminal device 116 is configured with a different SRB1 (relay terminal SRB1) than the non-split SRB1 configuration (remote terminal SRB1) of the remote terminal device 102. The relay terminal device uses relay terminal SRB1 to transmit the UL RRC message containing the encapsulated failure report 106 to the network 104. If the relay serving cell is different from the direct link serving cell of the remote terminal, the information in the UL RRC message is forwarded to the direct link serving cell of the remote terminal. The UL PC5-RRC message and the UL RRC message each include a remote terminal identifier and a cell identifier for the remote terminal direct link serving cell, and the failure report 106 includes one or more link quality measurements.

[0024] Figure 1B is a block diagram of a system 100 illustrating an example where RLF 130 occurs on an indirect communication link 114 and a remote terminal device 102 transmits a failure report 106 with link quality measurement 108 to a direct link serving cell 112 on a direct communication link 110. The link quality measurement 108 includes at least one sidelink quality measurement of a sidelink to a candidate relay device. In this example, the remote terminal device 102 measures a communication link 124 to another cell 126 and a sidelink 120 to a candidate relay device 122 to determine the RSRP and / or SL-RSRP of each alternative link 120, 124. The remote terminal device 102 may measure any number of alternative links. The failure report 106 is transmitted in an uplink (UL) RRC message 132 using the SRB1 configuration of the remote terminal device 102. In this example, the UL RRC message 132 is a MCG failure information (MCGFailureInformation) message defined in one or more revisions of the 3GPP communication specification, but the MCG failure information message of this example is different in that it includes additional information related to the link quality measurement 108. Examples of suitable techniques for communicating link quality measurement information include associating the RSRP and / or SL-RSRP value with a cell identifier identifying an alternative cell providing an alternative link, or a terminal identifier identifying a candidate relay terminal device.

[0025] Figure 1C is a block diagram of system 100 showing an example of terminal reconfiguration in response to a fault report 106 received for the RLF of indirect communication link 114. After receiving the fault report information, the remote terminal direct link serving cell 112 determines the desired action for the remote terminal device 102 and sends a dedicated control channel (DCCH) message 134 to the remote terminal device 102. An example of a desired action is to reconfigure the remote terminal device 102 on a single communication path, which can be a direct or indirect communication path. The direct communication path may be the current direct communication link 110 or a new direct communication link to another cell. Thus, the direct link serving cell 112 may, depending on the circumstances, call a handover to a new cell. The direct link serving cell 112 may also reconfigure the remote terminal device 102 on a multipath connection, including a new indirect communication link via a candidate relay terminal device. If all available alternative paths are of poor quality, the desired action may include transitioning the remote terminal device to RRC_IDLE or RRC_INACTIVE. For example, if the SL-RSRP measurement 108 included in the failure report 106 indicates that the channel quality of the available indirect paths is below a threshold and the direct communication link 110 is below a quality threshold, the remote terminal direct link serving cell may send an RRC release message to move the remote terminal device to IDLE or INACTIVE. Depending on the circumstances, the remote terminal device 102 may be reconfigured with a different SRB1. If the original SRB1 configuration of the multipath connection was a non-split SRB1, the new SRB1 configuration may be a split SRB1.

[0026] In the example in Figure 1C, the remote terminal device 102 is reconfigured with a multipath connection including the original direct communication link 110 and a new indirect communication path 136 via the candidate relay terminal device 122. The remote terminal direct link serving cell 112 generates a dedicated control channel (DCCH) message 134 to reconfigure the remote terminal device 102. The direct link serving cell 112 in the network 104 sends a DL RRC message 138 containing the DCCH message 134. In response to the DCCH message 134, the remote terminal device 102 establishes a new relay communication link 136 according to the prior art. The relay communication link 136 may be through the direct link serving cell 112 or through the relay serving cell 140. The box representing the relay serving cell 140 includes a dashed line to indicate that a different cell may be used than the direct link serving cell 112. The relay serving cell 140 may be provided by the same network node that provides the direct link serving cell 112 or by a different network node.

[0027] Therefore, the remote terminal device 102 detects an RLF on the indirect path during multipath operation and, accordingly, sends a fault report to the direct link serving cell indicating that an RLF has occurred and including one or more RSRP or SL-RSRP measurements (link quality measurement 108) of the alternative communication link. The direct link serving cell 112 evaluates the link quality measurement 108 and, based at least in part on the measurement, determines the appropriate action for the remote terminal device 102. The serving cell 112 generates a DCCH message and sends it to the remote terminal device as a DL RRC message on the direct communication link 110. In this example, the DCCH message instructs the remote terminal device to establish an indirect communication link (new relay communication link) 136 via the candidate relay terminal device 122. In response to the DCCH message, the remote terminal device 102 establishes the relay communication link 136 and maintains multipath connectivity to the network 104.

[0028] In the following examples, network nodes and terminal devices are represented as base stations and UE devices, respectively. The functions and operations performed by base stations and UE devices may apply to other types of network nodes and terminal devices. These examples and embodiments are merely preferred examples and are not intended to limit the disclosure. Accordingly, the system may include any desired combination of base stations, UE devices, and other equipment, while remaining within the scope of the disclosure.

[0029] Figure 2 is a block diagram showing an example of a base station 200 suitable for use as a network node. The base station 200 includes electronic equipment 204, a transmitter 206, a receiver 208, and multiple antennas 210, as well as other electronic equipment, hardware, and code. The base station 200 is any fixed, mobile, or portable device that performs the functions described herein. Various functions and operations of the blocks described with reference to the base station 200 and network node 102 can be implemented in any number of devices, circuits, or elements. Two or more functional blocks may be integrated into a single device, and functions described as being performed in a single device may be implemented across multiple devices. The base station 200 may be a fixed device or equipment installed in a specific location during system deployment. Examples of such equipment include a fixed base station or fixed transceiver station. Although base stations may be referred to by different terms, when operating according to one or more communication specifications of 3GPP V2X operation, a base station is usually called a gNodeB or gNB. In some circumstances, the base station 200 may be a mobile device temporarily installed in a specific location. Some examples of such equipment include mobile transceiver stations that may include power generation equipment such as generators, solar panels, and / or batteries. Larger and heavier versions of such equipment may be transported by trailer. In yet another scenario, the base station 200 may be a portable device that is not fixed in a specific location.

[0030] The electronic device 204 includes any combination of hardware, software, and / or firmware for communicating with and controlling other base station components that perform the functions described herein, and for facilitating the overall functionality of the base station 200. Thus, the electronic device 204 works in coordination with other base station 200 components to initiate tasks and perform the operations and functions of the base station 200. Examples of a suitable electronic device 204 include a microprocessor connected to memory or code that runs on a processor configuration. The transmitter 206 includes an electronic device configured to transmit radio signals. Depending on the circumstances, the transmitter 206 may include multiple transmitters. The receiver 208 includes an electronic device configured to receive radio signals. Depending on the circumstances, the receiver 208 may include multiple receivers. The receiver 208 may receive signals via multiple antennas 210, or via a selected antenna from among the multiple antennas 210. The antennas 210 may include separate transmitting and receiving antennas.

[0031] In the example in Figure 2, the transmitter 206 and receiver 208 perform radio frequency (RF) processing, including modulation and demodulation. Therefore, the receiver 208 may include components such as a low-noise amplifier (LNA) and filters. The transmitter 206 may include filters and amplifiers. Other components may include isolators, matching circuits, and other RF components. These components work in combination and in coordination with other components to perform the functions of a base station. The required components may depend on the specific functions required of the base station 200.

[0032] The transmitter 206 includes a modulator (not shown), and the receiver 208 includes a demodulator (not shown). The modulator modulates the signal transmitted as part of the downlink signal and can apply one of several modulation orders. The demodulator demodulates any uplink signal received at the base station 200 according to one of the several modulation orders. The electronic device 204 works in conjunction with the transmitter 206 to apply a precoder matrix to the signal transmitted through the multiple antennas 210.

[0033] The base station 200 includes a communication interface 212 for communicating with other base stations, other network components, and other entities such as servers and databases. The communication interface 212 may be connected to a backhaul or network that enables communication with other base stations. Depending on the circumstances, the links between base stations may include at least some wireless components. Therefore, the communication interface 212 may include wireless communication capabilities and may utilize some components of the transmitter 206 and / or receiver 208.

[0034] The electronic device 204 works in conjunction with the receiver 208 to measure and evaluate signals transmitted by the UE device. Therefore, the electronic device 204 and receiver 206 can receive, measure, and evaluate uplink signals, including reference signals, transmitted by the UE device. The signal measurements and evaluations can be stored in memory 214 and, in some cases, used to determine the location of the UE device.

[0035] The electronic device 204 works in conjunction with the transmitter 206 and the antenna 210 to process the output signal and precode the signal to be transmitted to the UE device. Thus, the electronic device 204 and the transmitter 206 apply an appropriate MU-MIMO precoder to the signal to be transmitted to a specific UE device.

[0036] Figure 3 is a block diagram showing examples of UE devices 300 suitable for use as terminal devices 102, 116, and 122. In some examples, the UE device 300 is any wireless communication device such as a mobile phone, transceiver modem, personal digital assistant (PDA), tablet, or smartphone. In other examples, the UE device 300 is a machine-type communication (MTC) communication device or an Internet of Things (IoT) device. Thus, the UE device 300 is any fixed, mobile, or portable device that performs the functions described herein. Various functions and operations of the blocks described with reference to the UE device 300 can be implemented in any number of devices, circuits, or elements. Two or more functional blocks may be integrated into a single device, and functions described as being performed in a single device may be implemented across multiple devices.

[0037] The UE device 300 includes at least an electronic device 302, a transmitter 304, and a receiver 306. The electronic device 302 includes any combination of hardware, software, and / or firmware for communicating with and controlling other UE device components to perform the functions described herein and to facilitate the overall functionality of the communication device. Thus, the electronic device 302 works in cooperation with other UE device components to initiate tasks and perform the operation and functions of the UE device 300. An example of a suitable electronic device 302 is code that runs on a microprocessor or processor configuration connected to memory 310. The transmitter 304 includes an electronic device configured to transmit radio signals. Depending on the circumstances, the transmitter 304 may include multiple transmitters. The receiver 306 includes an electronic device configured to receive radio signals. Depending on the circumstances, the receiver 306 may include multiple receivers. The receiver 306 and the transmitter 304 receive and transmit signals, respectively, via an antenna 308. The antenna 308 may include separate transmitting and receiving antennas. Depending on the circumstances, antenna 308 may include multiple transmitting and receiving antennas.

[0038] In the example in Figure 3, the transmitter 304 and receiver 306 perform radio frequency (RF) processing, including modulation and demodulation. Therefore, the receiver 306 may include components such as a low-noise amplifier (LNA) and filters. The transmitter 304 may include filters and amplifiers. Other components may include isolators, matching circuits, and other RF components. These components work in combination and in coordination with other components to perform the functions of the communication device. The required components may depend on the specific functions required of the communication device.

[0039] The transmitter 304 includes a modulator (not shown), and the receiver 306 includes a demodulator (not shown). The modulator can apply any one of several modulation orders to modulate the signal transmitted as part of the uplink signal. The demodulator demodulates the downlink signal according to any one of the several modulation orders.

[0040] UE device 300 can not only communicate with the base station but also send and receive sidelink signals with other UE devices. Electronic device 302 works in conjunction with receiver 306 to measure and evaluate signals transmitted by other devices such as base stations and UE devices. Thus, electronic device 302 and receiver 306 can receive, measure, and evaluate downlink reference signals transmitted by the base station. The measured and evaluated signals can be stored in memory 310. Electronic device 302 and receiver 306 can also receive, measure, and evaluate discovery signals transmitted by nearby UE devices to generate an adjacent list containing adjacent UE devices within maximum distance. The adjacent list can be stored in memory 310 and transmitted to the base station.

[0041] Figure 4 is a flowchart illustrating a method for reporting a wireless link failure during multipath operation. This method may be performed in a system such as system 100 discussed herein. This method is performed by a terminal device such as a remote terminal device 102 or a UE device 300 and may be performed using any of several techniques, including any combination of electronic devices, software, hardware, and firmware. For example, software code running on an electronic device including a processor, computer, or other processor configuration within the remote terminal device 102 may facilitate the generation, formatting, and transmission of the failure report 106. Steps may be performed in a different order, omitted, combined, or in parallel than those described or illustrated in Figure 4. Further examples may include additional steps not explicitly described in the examples described with reference to Figure 4. For example, a step for obtaining link quality measurements may be performed even if not explicitly shown in Figure 4.

[0042] In step 402, a U2N multipath connection is maintained between the remote terminal device and the network 104, where the U2N multipath connection includes a direct communication link 110 and an indirect communication link (relay communication link) 114. As described above, the serving cell of the relay terminal device and the serving cell of the remote terminal device may be the same cell or different cells. If the cells are different, each cell may be served by a different network node or by the same network node.

[0043] In step 404, an RLF is detected on either communication link 110 or 114 of the U2N multipath connection. The remote terminal device determines that an RLF occurred on either the direct communication link 110 or the indirect communication link 114.

[0044] In step 406, a fault report is sent to the network. The remote terminal device generates and sends a fault report for transmission over a communication link that has not experienced an RLF. Here, the fault report indicates that an RLF has occurred and comprises one or more link quality measurements. The link quality measurements include at least one sidelink quality measurement of the sidelink to the candidate relay device. In some examples, the link quality measurements are RSRP and SL-RSRP measurements of the links to the alternate cell and the candidate relay terminal device, and may also include an RSRP measurement of the current link. If an RLF occurs on the indirect communication link 114, the remote terminal device sends a UL RRC message to the serving cell on the direct communication link. The UL RRC message includes a fault report and may follow the conventional MCG fault information (MCGFailureInformation) message, but comprises link quality measurements including at least one sidelink quality measurement to the candidate relay device. If an RLF occurs on the direct communication link 110 and the remote terminal device is configured as a split SRB1, the remote terminal device sends a UL RRC message to the network via the relay terminal device on the indirect communication link. If the relay serving cell and the direct link serving cell are different cells, the message (or information based on the message) is forwarded to the serving cell of the remote terminal device. The UL RRC message includes fault reporting and may follow the conventional MCG fault information message but includes link quality measurement.

[0045] When the remote terminal device is configured in an undivided SRB1 configuration and an RLF occurs on the direct communication link, the remote terminal device 102 generates and transmits a UL PC5-RRC message containing an encapsulated version of the fault report. The relay terminal device 116 receives the UL PC5-RRC message containing the fault report 106 on the PC5 connection and generates a UL RRC message containing the encapsulated fault report 106. The relay terminal device 116 is configured with a different SRB1 (relay terminal SRB1) than the undivided SRB1 configuration (remote terminal SRB1) of the remote terminal device 102. The relay terminal device uses the relay terminal SRB1 to transmit the UL RRC message containing the encapsulated fault report 106 to the network 104. If 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. The UL PC5-RRC message and the UL RRC message each contain a remote terminal identifier and a cell identifier of the remote terminal direct link serving cell, and the fault report 106 contains one or more link quality measurements.

[0046] In step 408, a DCCH message is received from serving cell 112. The DCCH message is at least partially based on the link quality measurement reported in fault report 106. If the DCCH message is received over an indirect communication link and the remote terminal device is configured as an undivided SRB1, the DCCH message is received as a PC5-RRC message from the relay terminal device.

[0047] In step 410, the remote terminal device performs the operations indicated by the DCCH message, which may include operations such as performing a handover to an alternate cell, establishing an alternate indirect communication link, establishing a new SRB1 configuration, transitioning to RRC_INACTIVE, and transitioning to RRC_IDLE.

[0048] To clearly demonstrate this compatibility of hardware, firmware, and software, various exemplary components, blocks, modules, circuits, and steps are described above in general terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software, or as a combination of these technologies, depends on the design constraints imposed on the particular application and the overall system. The described functionality can be implemented in various ways for each particular application, but such implementation decisions do not constitute a departure from the scope of this disclosure. Depending on the various embodiments, processors, devices, components, circuits, structures, machines, modules, etc., may be configured to perform one or more of the functions described herein. The terms “configured to” or “configured for” used herein for a particular operation or function refer to processors, devices, components, circuits, electronic devices, and equipment that are physically constructed, programmed, directed, and / or positioned to perform a particular operation or function. Furthermore, the various exemplary logic blocks, modules, devices, components, and circuits described herein may be implemented or run within integrated circuits (ICs), which may include general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), other electronic devices, or combinations thereof. These may be ASICs, field-programmable gate arrays (FPGAs), or other programmable logic devices, or any combination thereof. The logic blocks, electronic devices, and circuits may further include antennas and / or transceivers for communication with various components within a network or device. The general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, or state machine.The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors working in conjunction with a DSP core, or any other suitable configuration for performing the functions described herein.

[0049] When implemented in software, the functionality may be stored as one or more instructions or codes on a computer-readable medium. Therefore, steps of the methods or algorithms disclosed herein may be implemented as software stored on a computer-readable medium. Computer-readable mediums include both computer storage media and communication media, including any medium on which computer programs or code can be transferred from one location to another. The storage medium may be any available medium accessible from a computer. As an example, but not limited to, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or other media accessible by a computer that can be used to store desired program code in the form of instructions or data structures.

[0050] Therefore, the methods and apparatus of the present invention can, at least in part, take the form of program logic or program code (i.e., instructions) embodied in a tangible medium 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 present invention. Alternatively, the methods and apparatus of the present invention may be embodied in the form of program code transmitted through some transmission medium, such as through electrical wiring or cables, optical fibers, or other forms of transmission. When the program code is received, loaded into and executed by a machine such as a computer, the machine becomes an apparatus for practicing the present invention. When implemented on a general-purpose processor, the program code combines with the processor to provide a unique apparatus that operates similarly to a specific logic circuit.

[0051] Furthermore, memory or other storage, as well as communication components, may be incorporated into embodiments of this disclosure. For clarity, it will be understood that the above description has referred to different functional units and processors to describe embodiments of this disclosure. However, it will be apparent that any appropriate distribution of functionality between different functional units, processing logic elements, or domains may be used without departing from this 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. Thus, references to specific functional units are not intended to indicate a strict logical or physical structure or organization, but merely to refer to appropriate means for providing the described functionality.

[0052] Clearly, in view of these teachings, other embodiments and modifications of the invention will readily come to mind for those skilled in the art. The above description is illustrative and not limiting. The invention should be limited only by the appended claims, which, when considered together with the above specification and accompanying drawings, include all such embodiments and modifications. Accordingly, the scope of the invention should not be determined by reference to the above description, but rather by reference to the appended claims together with the full scope of the equivalent.

Claims

1. Maintaining a U2N multipath connection with the network, wherein the U2N multipath connection includes a direct communication link to the direct link serving cell of the current network node of the network and an indirect communication link to the network via a relay terminal device. Determining that a wireless link failure (RLF) has occurred in either the direct communication link or the indirect communication link, The system includes, upon determining that the RLF has occurred, sending a fault report message to the network, the fault report indicating that the RLF has occurred, and including at least one sidelink quality measurement for an alternative sidelink communication link other than the indirect communication link. Communication method.

2. Determining that an RLF has occurred includes determining that the RLF occurred on the indirect communication link, and transmitting the fault report includes transmitting the fault report on the direct communication link. The communication method according to claim 1.

3. The at least one link quality measurement includes at least one measurement of the sidelink reference signal received power (SL-RSRP) of the sidelink communication link to an alternative relay terminal device. The communication method according to claim 1.

4. The at least one link quality measurement includes a current cell RSRP measurement of the direct communication link. The communication method according to claim 3.

5. The fault report is an MCG fault information (MCGFailureInformation) message having a link quality measurement field for transmitting the at least one link quality measurement. The communication method according to claim 3.

6. Determining that an RLF has occurred includes determining that the RLF occurred on the direct communication link, and transmitting the fault report includes transmitting the fault report on the indirect communication link. The communication method according to claim 1.

7. Transmitting the fault report includes transmitting an uplink (UL) direct communication interface (PC5) radio resource control (RRC) message (UL PC5-RRC message) to the relay terminal device, which contains an encapsulated direct radio link fault report generated in response to the detection of a radio link fault in the direct path communication link. The communication method according to claim 6.

8. The aforementioned at least one sidelink quality measurement includes at least one measurement of the sidelink reference signal received power (SL-RSRP) of the sidelink communication link to an alternative relay terminal device. The communication method according to claim 7.

9. The at least one link quality measurement includes a current cell RSRP measurement of the direct communication link. The communication method according to claim 8.

10. A transceiver including a transmitter and a receiver, wherein the transceiver maintains a U2N multipath connection with a network, and the U2N multipath connection includes a direct communication link to a direct link serving cell of the current network node of the network and an indirect communication link to the network via a relay terminal device, The system includes an electronic device that determines whether a wireless link fault (RLF) has occurred in either the direct communication link or the indirect communication link, The transmission includes, in response to determining that the RLF has occurred, sending a fault report message to the network, the fault report indicating that the RLF has occurred, and including at least one sidelink quality measurement for an alternative sidelink communication link other than the indirect communication link. Remote terminal device.

11. The electronic device determines that the RLF occurred on the indirect communication link, and the transmitter transmits the fault report on the direct communication link. The remote terminal device according to claim 10.

12. The aforementioned at least one sidelink quality measurement includes at least one measurement of the sidelink reference signal received power (SL-RSRP) of the sidelink communication link to an alternative relay terminal device. The remote terminal device according to claim 10.

13. The at least one link quality measurement includes a current cell RSRP measurement of the direct communication link. The remote terminal device according to claim 12.

14. The fault report is an MCG fault information (MCGFailureInformation) message having a link quality measurement field for transmitting the at least one link quality measurement. The remote terminal device according to claim 12.

15. Maintaining a U2N multipath connection between the network and a remote terminal device, wherein the U2N multipath connection includes a direct communication link from the direct link serving cell of the current network node of the network and an indirect communication link from the network via a relay terminal device. Receiving a fault report message from the remote terminal device, wherein the fault report indicates that a radio link fault (RLF) occurred on either the direct communication link or the indirect communication link, and the fault report includes at least one sidelink quality measurement for an alternative sidelink communication link other than the indirect communication link. The method involves determining the desired operation of the remote terminal device based on at least a portion of the aforementioned at least one link quality measurement. Communication method.

16. The RLF occurred on the indirect communication link, and receiving the fault report includes receiving the fault report on the direct communication link. The communication method according to claim 15.

17. The aforementioned at least one sidelink quality measurement includes at least one measurement of the sidelink reference signal received power (SL-RSRP) of the sidelink communication link to an alternative relay terminal device. The communication method according to claim 16.

18. The at least one link quality measurement includes a current cell RSRP measurement of the direct communication link. The communication method according to claim 17.

19. The fault report is an MCG fault information (MCGFailureInformation) message having a link quality measurement field for transmitting the at least one link quality measurement. The communication method according to claim 17.

20. A transceiver including a transmitter and a receiver, wherein the transceiver maintains a U2N multipath connection between a network and a remote terminal device, and the U2N multipath connection includes a direct communication link from a direct link serving cell of the current network node of the network and an indirect communication link from the network via a relay terminal device, The receiver receives a fault report message from the remote terminal device, the fault report indicates that a radio link fault (RLF) occurred on either the direct communication link or the indirect communication link, and includes at least one sidelink quality measurement for alternative communication links other than the direct communication link and the indirect communication link, The electronic device comprises determining the desired operation of the remote terminal device based on at least a portion of the at least one link quality measurement. network.

21. A non-temporary computer-readable medium that stores computer-executable instructions that perform the following actions at runtime: The aforementioned method, Maintaining a U2N multipath connection with the network, wherein the U2N multipath connection includes a direct communication link to the direct link serving cell of the current network node of the network and an indirect communication link to the network via a relay terminal device. To determine whether a wireless link failure (RLF) occurred in either the direct communication link or the indirect communication link, The system includes, upon determining that the RLF has occurred, sending a fault report message to the network, the fault report indicating that the RLF has occurred, and including at least one sidelink quality measurement for alternative communication links other than the direct communication link and the indirect communication link. Non-temporary computer-readable media.

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