Communication control method

Abstract

To provide a method in which a radio node appropriately collects a log and transmits the collected log to a network node in a cellular communication system.SOLUTION: In a cellular communication system, a relay node receives configuration information for recording log information related to a predetermined feedback message from a donor node, and sends the predetermined feedback message to the donor node according to the configuration information, wherein the predetermined feedback message includes the log information collected before the predetermined feedback message is sent. The configuration information includes first time information for triggering transmission of a predetermined feedback message, and the log information includes second time information different from the first time information and information on an available buffer size.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to a communication control method for use in a cellular communication system. [Background technology]

[0002] The Third Generation Partnership Project (3GPP), a standardization project for cellular communication systems, is considering the introduction of a new relay node called an Integrated Access and Backhaul (IAB) node. One or more relay nodes intervene in communication between a base station and a user device and relay this communication. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS 38.300 V16.6.0 (2021-06) Summary of the Invention

[0004] A communication control method according to a first aspect is a communication control method used in a cellular communication system. The communication control method includes a step of transmitting, by a relay node, first information collected when transmitting a flow control feedback message or second information collected when receiving the flow control feedback message to a donor node. The communication control method also includes a step of receiving, by the donor node, the first information or the second information.

[0005] A communication control method according to a second aspect is a communication control method used in a cellular communication system. The communication control method includes a step of transmitting, to a donor node, third information collected when a relay node receives a notification about a backhaul link failure from a parent node of the relay node and fourth information collected when the relay node transmits the notification to a child node of the relay node. The communication control method also includes a step of receiving, by the donor node, the third information and the fourth information. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a cellular communication system according to an embodiment. [Figure 2] FIG. 2 is a diagram showing the relationship between IAB nodes, parent nodes, and child nodes. [Figure 3] FIG. 3 is a diagram illustrating an example configuration of a gNB (base station) according to an embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of an IAB node (relay node) according to an embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of the configuration of a UE (user equipment) according to an embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of a protocol stack related to an RRC connection and a NAS connection of an IAB-MT. [Figure 7] FIG. 7 is a diagram illustrating an example of a protocol stack for the F1-U protocol. [Figure 8] FIG. 8 is a diagram illustrating an example of a protocol stack for the F1-C protocol. [Figure 9] 9(A) and 9(B) are diagrams illustrating an example of flow control feedback according to the first embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of operation according to the first embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of the configuration of a cellular communication system according to the second embodiment. [Figure 12]FIG. 12 is a diagram illustrating an example of operation according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present disclosure aims to appropriately collect logs and transmit the collected logs to a donor node.

[0008] A cellular communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0009] (Configuration of a cellular communication system) An example of the configuration of a cellular communication system according to an embodiment will be described. The cellular communication system 1 according to an embodiment is a 3GPP 5G system. Specifically, the radio access method in the cellular communication system 1 is NR (New Radio), which is a 5G radio access method. However, LTE (Long Term Evolution) may be applied at least partially to the cellular communication system 1. Furthermore, future cellular communication systems such as 6G may also be applied to the cellular communication system 1.

[0010] FIG. 1 is a diagram showing an example of the configuration of a cellular communication system 1 according to an embodiment.

[0011] 1, the cellular communication system 1 includes a 5G core network (5GC) 10, user equipment (UE) 100, base station devices (hereinafter sometimes referred to as "base stations") 200-1 and 200-2, and IAB nodes 300-1 and 300-2. The base station 200 may be referred to as a gNB.

[0012] In the following, an example in which base station 200 is an NR base station will be mainly described, but base station 200 may also be an LTE base station (i.e., an eNB).

[0013] In the following, the base stations 200-1 and 200-2 may be referred to as gNB 200 (or base station 200), and the IAB nodes 300-1 and 300-2 may be referred to as IAB node 300.

[0014] The 5GC 10 has an Access and Mobility Management Function (AMF) 11 and a User Plane Function (UPF) 12. The AMF 11 is a device that performs various mobility controls for the UE 100. The AMF 11 manages information about the area in which the UE 100 is located by communicating with the UE 100 using Non-Access Stratum (NAS) signaling. The UPF 12 is a device that performs transfer control of user data, etc.

[0015] Each gNB 200 is a fixed wireless communication node and manages one or more cells. A cell is used as a term indicating the smallest unit of a wireless communication area. A cell may also be used as a term indicating a function or resource for performing wireless communication with a UE 100. One cell belongs to one carrier frequency. In the following, there may be cases where a cell and a base station are used interchangeably.

[0016] Each gNB 200 is interconnected with the 5GC 10 via an interface called an NG interface. Figure 1 illustrates two gNBs, gNB 200-1 and gNB 200-2, connected to the 5GC 10.

[0017] Each gNB 200 may be divided into a central unit (CU) and distributed units (DU). The CU and DU are connected to each other via an interface called an F1 interface. The F1 protocol is a communication protocol between the CU and DU, and includes an F1-C protocol, which is a control plane protocol, and an F1-U protocol, which is a user plane protocol.

[0018] The cellular communication system 1 supports IAB, which enables wireless relay of NR access using NR for backhaul. The donor gNB 200-1 (or donor node, hereinafter sometimes referred to as the "donor node") is the terminal node of the NR backhaul on the network side and is a donor base station with additional functionality to support IAB. The backhaul can be multi-hop via multiple hops (i.e., multiple IAB nodes 300).

[0019] FIG. 1 illustrates an example in which IAB node 300-1 wirelessly connects with donor node 200-1, IAB node 300-2 wirelessly connects with IAB node 300-1, and the F1 protocol is transmitted over two backhaul hops.

[0020] The UE 100 is a mobile wireless communication device that performs wireless communication with a cell. The UE 100 may be any device that performs wireless communication with the gNB 200 or the IAB node 300. For example, the UE 100 may be a mobile phone terminal or a tablet terminal, a laptop computer, a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle, or an aircraft or a device provided in an aircraft. The UE 100 wirelessly connects to the IAB node 300 or the gNB 200 via an access link. FIG. 1 shows an example in which the UE 100 is wirelessly connected to the IAB node 300-2. The UE 100 indirectly communicates with the donor node 200-1 via the IAB node 300-2 and the IAB node 300-1.

[0021] FIG. 2 is a diagram showing an example of the relationship between an IAB node 300, parent nodes, and child nodes.

[0022] As shown in FIG. 2, each IAB node 300 has an IAB-DU corresponding to a base station function unit and an IAB-MT (Mobile Termination) corresponding to a user equipment function unit.

[0023] An adjacent node (i.e., an upper node) on the NR Uu radio interface of the IAB-MT is called a parent node. The parent node is the DU of the parent IAB node or the donor node 200. The radio link between the IAB-MT and the parent node is called a backhaul link (BH link). FIG. 2 shows an example in which the parent nodes of the IAB node 300 are IAB nodes 300-P1 and 300-P2. The direction toward the parent node is called upstream. From the perspective of the UE 100, the upper node of the UE 100 may correspond to the parent node.

[0024] Neighboring nodes on the NR access interface of the IAB-DU (i.e., subordinate nodes ) are called child nodes. The IAB-DU manages cells, similar to the gNB 200. The IAB-DU terminates the NR Uu radio interface to the UE 100 and the subordinate IAB nodes. The IAB-DU supports the F1 protocol to the CU of the donor node 200-1. In FIG. 2, an example is shown in which the child nodes of the IAB node 300 are IAB nodes 300-C1 to 300-C3, but the child nodes of the IAB node 300 may also include the UE 100. The direction toward the child nodes is called downstream.

[0025] (Base station configuration) Next, the configuration of the gNB 200, which is a base station according to the embodiment, will be described. Fig. 3 is a diagram showing an example configuration of the gNB 200. As shown in Fig. 3, the gNB 200 has a radio communication unit 210, a network communication unit 220, and a control unit 230.

[0026] The wireless communication unit 210 performs wireless communication with the UE 100 and wireless communication with the IAB node 300. The wireless communication unit 210 has a receiving unit 211 and a transmitting unit 212. The receiving unit 211 performs various types of reception under the control of the control unit 230. The receiving unit 211 includes an antenna, and converts (down-converts) a wireless signal received by the antenna into a baseband signal (received signal), and outputs the signal to the control unit 230. The transmitting unit 212 performs various types of transmission under the control of the control unit 230. The transmitting unit 212 includes an antenna, and converts (up-converts) a baseband signal (transmitted signal) output by the control unit 230 into a wireless signal, and transmits the signal from the antenna.

[0027] The network communication unit 220 performs wired communication (or wireless communication) with the 5GC10 and wired communication (or wireless communication) with other adjacent gNBs 200. The network communication unit 220 has a receiving unit 221 and a transmitting unit 222. The receiving unit 221 performs various types of reception under the control of the control unit 230. The receiving unit 221 receives a signal from the outside and outputs the received signal to the control unit 230. The transmitting unit 222 performs various types of transmission under the control of the control unit 230. The transmitting unit 222 transmits the transmission signal output by the control unit 230 to the outside.

[0028] The control unit 230 performs various controls in the gNB 200. The control unit 230 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes. The processor performs processing of each layer, which will be described later. Furthermore, in each embodiment, the control unit 230 may perform each process or operation in the gNB 200.

[0029] (Relay node configuration) Next, the configuration of the IAB node 300, which is a relay node (or relay node device; hereinafter, sometimes referred to as a "relay node") according to the embodiment, will be described. FIG. 4 is a diagram showing an example configuration of the IAB node 300. As shown in FIG. 4, the IAB node 300 has a wireless communication unit 310 and a control unit 320. The IAB node 300 may have multiple wireless communication units 310.

[0030] The wireless communication unit 310 performs wireless communication (BH link) with the gNB 200 and wireless communication (access link) with the UE 100. The wireless communication unit 310 for BH link communication and the wireless communication unit 310 for access link communication may be provided separately.

[0031] The wireless communication unit 310 has a receiving unit 311 and a transmitting unit 312. The receiving unit 311 performs various types of reception under the control of the control unit 320. The receiving unit 311 includes an antenna, and converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal), and outputs the signal to the control unit 320. The transmitting unit 312 performs various types of transmission under the control of the control unit 320. The transmitting unit 312 includes an antenna, and converts (up-converts) a baseband signal (transmitted signal) output by the control unit 320 into a radio signal, and transmits the signal from the antenna.

[0032] The control unit 320 performs various controls in the IAB node 300. The control unit 320 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs executed by the processor and information used in processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes. The processor performs processing of each layer, which will be described later. In each embodiment, the control unit 320 may also perform each process or operation in the IAB node 300.

[0033] (Configuration of user device) Next, a description will be given of a configuration of a UE 100 which is a user equipment according to the embodiment. Fig. 5 is a diagram showing an example of the configuration of the UE 100. As shown in Fig. 5, the UE 100 includes a radio communication unit 110 and a control unit 120.

[0034] The radio communication unit 110 performs radio communication in the access link, i.e., radio communication with the gNB 200 and radio communication with the IAB node 300. The radio communication unit 110 may also perform radio communication in the side link, i.e., radio communication with another UE 100. The radio communication unit 110 has a receiving unit 111 and a transmitting unit 112. The receiving unit 111 performs various receptions under the control of the control unit 120. The receiving unit 111 includes an antenna, and converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal), and outputs the signal to the control unit 120. The transmitting unit 112 performs various transmissions under the control of the control unit 120. The transmitting unit 112 includes an antenna, and converts (up-converts) a baseband signal (transmitted signal) output by the control unit 120 into a radio signal, and transmits the signal from the antenna.

[0035] The control unit 120 performs various controls in the UE 100. The control unit 120 includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs executed by the processor and information used in the processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processing. The processor performs processing of each layer, which will be described later. Furthermore, the control unit 130 may perform each processing in the UE 100 in each of the embodiments shown below.

[0036] (Protocol stack configuration) Next, a configuration of a protocol stack according to an embodiment will be described. Fig. 6 is a diagram showing an example of a protocol stack related to an RRC connection and a NAS connection of an IAB-MT.

[0037] As shown in FIG. 6, the IAB-MT of the IAB node 300-2 includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a radio resource control (RRC) layer. It has a Control layer and a Non-Access Stratum (NAS) layer.

[0038] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the IAB-MT of IAB node 300-2 and the PHY layer of the IAB-DU of IAB node 300-1 via a physical channel.

[0039] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of the IAB-MT in IAB node 300-2 and the MAC layer of the IAB-DU in IAB node 300-1 via a transport channel. The MAC layer of the IAB-DU includes a scheduler, which determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the allocated resource blocks.

[0040] The RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the IAB-MT of IAB node 300-2 and the RLC layer of the IAB-DU of IAB node 300-1 via logical channels.

[0041] The PDCP layer performs header compression / decompression and encryption / decryption. Data and control information are transmitted between the PDCP layer of the IAB-MT of the IAB node 300-2 and the PDCP layer of the donor node 200 via a radio bearer.

[0042] The RRC layer controls logical channels, transport channels, and physical channels in response to the establishment, re-establishment, and release of radio bearers. RRC signaling for various settings is transmitted between the RRC layer of the IAB-MT of the IAB node 300-2 and the RRC layer of the donor node 200. When there is an RRC connection with the donor node 200, the IAB-MT is in an RRC connected state. When there is no RRC connection with the donor node 200, the IAB-MT is in an RRC idle state.

[0043] The NAS layer, which is positioned above the RRC layer, performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the IAB-MT of the IAB node 300-2 and the AMF 11.

[0044] Figure 7 is a diagram showing a protocol stack for the F1-U protocol. Figure 8 is a diagram showing a protocol stack for the F1-C protocol. Here, an example is shown in which the donor node 200 is divided into a CU and a DU.

[0045] As shown in Figure 7, the IAB-MT of IAB node 300-2, the IAB-DU of IAB node 300-1, the IAB-MT of IAB node 300-1, and the DU of donor node 200 each have a BAP (Backhaul Adaptation Protocol) layer above the RLC layer. The BAP layer is a layer that performs routing processing and bearer mapping / demapping processing. In the backhaul, the IP layer is transmitted via the BAP layer, enabling routing over multiple hops.

[0046] In each backhaul link, PDUs (Protocol Data Units) of the BAP layer are transmitted via a backhaul RLC channel (BH NR RLC channel). Configuring multiple backhaul RLC channels in each BH link enables traffic prioritization and Quality of Service (QoS) control. The association between BAP PDUs and backhaul RLC channels is performed by the BAP layer of each IAB node 300 and the BAP layer of the donor node 200.

[0047] As shown in FIG. 8, the protocol stack of the F1-C protocol has an F1AP layer and an SCTP layer instead of the GTP-U layer and UDP layer shown in FIG.

[0048] In the following, the processing or operations performed by the IAB-DU and IAB-MT of the IAB may be simply referred to as the processing or operations of the "IAB." For example, the transmission of a BAP layer message from the IAB-DU of IAB node 300-1 to the IAB-MT of IAB node 300-2 will be described as the IAB node 300-1 sending the message to IAB node 300-2. In addition, the processing or operations of the DU or CU of the donor node 200 may be simply referred to as the processing or operations of the "donor node."

[0049] Also, the upstream direction and the uplink (UL) direction may be used interchangeably, and the downstream direction and the downlink (DL) direction may be used interchangeably.

[0050] [First embodiment] Next, a first embodiment will be described.

[0051] First, SON (Self Organizing / Optimizing Network) and MDT (Minimization of Drive Tests) in the first embodiment will be described.

[0052] (SON and MDT) In the cellular communication system 1, there are many nodes, including the base station 200. Therefore, the cellular communication system 1 may incur a large operational cost associated with its management.

[0053] SON is a concept introduced to reduce these operational costs. SON is a technology that autonomously organizes and optimizes networks. Specifically, SON is a technology that aims to continuously optimize networks in response to dynamic changes, optimize parameters for troubleshooting, and optimize coverage and capacity.

[0054] Utilizing these SON functions to automate processes such as network planning, configuration, and optimization reduces the workload of operators (telecommunications carriers) and cuts operational costs. The SON algorithm itself is not specified by 3GPP. In other words, SON algorithms are implementation-dependent. For example, the following SON algorithm takes wireless environment measurement data and the implementation status of various communication protocols (e.g., handover process success / failure) as input data, uses this input data to calculate optimal values ​​for network equipment (e.g., the antenna tilt angle of a base station) through computer simulation, and then automatically performs a series of tasks:

[0055] On the other hand, when installing base station 200, measurements of the radio environment (coverage area) are performed. Such measurements are performed by driving a measurement vehicle (or radio wave measurement vehicle) equipped with measurement equipment. Then, based on the measurement results, optimization is performed, such as changing the antenna tilt of the base station, and then the radio wave measurement vehicle is driven again to confirm the effectiveness. In this way, performing a drive test to actually measure the radio environment and collect measurement data requires a lot of man-hours and is costly.

[0056] That's why MDT was introduced. MDT is a technology that supports the collection of measurement values ​​specific to UE 100. With MDT, measurement data that was previously collected through drive tests using an electrical measurement vehicle can now be collected using UE 100. This makes it possible to automate measurement and collection, reducing man-hours and costs.

[0057] MDT has two modes: logged MDT and immediate MDT. In logged MDT, UE 100 in an idle state, an inactive state, or the like records (logs) measurement results, that is, UE 100 does not immediately report the measurement results to base station 200, but reports the log to base station 200 after acquiring the measurement results (in response to a request from base station 200). On the other hand, in immediate MDT, UE 100 in a connected state performs measurements based on RRC settings and reporting procedures related to measurements.

[0058] (Communication control method in the first embodiment) Fig. 9(A) is a diagram illustrating an example of flow control feedback according to the first embodiment. Fig. 9(A) illustrates an example of flow control feedback in the downstream direction.

[0059] Downstream flow control is supported by the BAP layer of the IAB node 300. The IAB-MT (BAP entity) of the IAB node 300-T triggers flow control feedback when the buffer load exceeds a certain level. Alternatively, the IAB-MT of the IAB node 300-T triggers flow control feedback when it receives a flow control poll from the parent node 300-P of the IAB node 300-T. When triggering flow control feedback, the IAB-MT of the IAB node 300-T generates flow control feedback including information such as the available buffer size. The IAB-MT of the IAB node 300-T transmits the generated flow control feedback to the parent node 300-P. The flow control feedback is transmitted using a BAP Control PDU. For example, upon receiving the flow control feedback, the parent node 300-P can reduce the amount of data transmitted downstream to the IAB node 300-T or refrain from transmitting data at all. This makes it possible to suppress buffer overflow in the IAB node 300-T. Buffer overflow is a phenomenon in which the IAB node 300-T is unable to forward (transmit) data received from the parent node 300-P to the child node, so the data continues to be held in the buffer (memory) of the IAB node 300-T, eventually exceeding the buffer size. Such buffer overflow can be suppressed by the parent node 300-P reducing the amount of data sent to the IAB node 300-T or refraining from sending data altogether. It is also possible to suppress congestion between the IAB node 300-P and the IAB node 300-T.

[0060] 3GPP has specified such downstream flow control, but is currently studying upstream flow control.

[0061] Fig. 9(B) is a diagram illustrating an example of flow control feedback according to the first embodiment, Fig. 9(B) illustrates an example of flow control in the upstream direction.

[0062] 9(B), IAB node 300-T transmits flow control feedback to child node 300-C of IAB node 300-T. In response to receiving the flow control feedback, child node 300-C can reduce the amount of data or control signals it transmits (upstream) to IAB node 300-T, or refrain from transmitting them altogether.

[0063] As shown in Figures 9(A) and 9(B), flow control is basically a control between IAB nodes 300. In order to avoid congestion between IAB nodes, it may be better for the IAB node 300-T to report to the donor node 200. This is because the donor node 200 may receive the report and seek a fundamental solution to the congestion between the IAB nodes 300, such as changing the routing settings. This also makes it possible to optimize the entire topology.

[0064] Therefore, in the first embodiment, the IAB node 300-T transmits information collected by transmitting or receiving flow control feedback to the donor node 200. Specifically, first, the relay node (e.g., the IAB node 300-T) transmits first information collected when transmitting flow control feedback or second information collected when receiving a flow control feedback message to the donor node (e.g., the donor node 200). Second, the donor node receives the first information or the second information.

[0065] In the following, downstream flow control feedback may be referred to as DL flow control feedback. Also, upstream flow control feedback may be referred to as UL flow control feedback. Figure 9(A) shows an example of sending DL flow control feedback. Also, Figure 9(B) shows an example of sending UL flow control feedback.

[0066] (Operation example of the first embodiment) FIG. 10 is a diagram illustrating an example of operation according to the first embodiment.

[0067] 10 , in step S10, the donor node 200 may transmit configuration information for recording a log related to flow control feedback to the IAB node 300. For example, the CU of the donor node 200 may transmit an RRC message including the configuration information to the IAB-MT of the IAB node 300. Also, for example, the CU of the donor node 200 may transmit an F1AP message including the configuration information to the IAB-DU of the IAB node 300.

[0068] The setting information may include the following information:

[0069] (A1) Information indicating whether to record a log of DL flow control feedback, a log of UL flow control feedback, or both flow control feedbacks.

[0070] (A2) Information indicating whether to record the transmission record of flow control feedback as a log, record the reception record of flow control feedback as a log, or record both as logs.

[0071] (A3) Information indicating whether to record the buffer size (Available Buffer Size). The buffer size may correspond to the buffer size included in the BAP Control PDU when the flow control feedback is transmitted in the BAP Control PDU.

[0072] (A4) BH RLC Channel ID to be recorded as a log.

[0073] (A5) Recording Trigger Condition: The recording trigger condition is a trigger condition for recording a log related to flow control feedback in a memory or the like. The recording trigger condition may be one of the following two conditions.

[0074] (A5-1) Periodic: Recording trigger conditions for periodically recording logs. The conditions may include the interval (or cycle) for periodically recording, the recording period, etc.

[0075] (A5-2) Event-triggered: This is a recording trigger condition for recording a log when an event occurs (event trigger). The event may be when flow control feedback is sent or when flow control feedback is received. Alternatively, the event may be when DL flow control feedback is sent or when DL flow control feedback is received. Alternatively, the event may be when UL flow control feedback is sent or when UL flow control feedback is received.

[0076] (A6) Report trigger condition. This is a trigger condition for reporting (or transmitting) the log acquired by the IAB node 300 to the donor node 200. The report trigger condition may be the same as the recording trigger condition. When the report trigger condition occurs, the IAB node 300 reports (or transmits) the recorded log (or generated log) to the donor node 200. The report trigger condition in this case may correspond to the immediate MDT described above. The report trigger condition may also be the time of an inquiry from the donor node 200 (or another IAB node). The IAB node 300 may report (or transmit) the recorded log to the donor node 200 when an inquiry is received from the donor node 200 (or another IAB node). The report trigger condition in this case may correspond to the log MDT described above.

[0077] (A7) Identifier of the IAB node to be measured. Indicates the identifier of the IAB node that is the source or destination of the flow control feedback received or transmitted by the IAB node 300. The IAB node 300 records only the processing related to the IAB node identifier. If the IAB node identifier is not set, the IAB node 300 may record the processing related to all IAB nodes.

[0078] In step S11, the IAB node 300 records a log related to the flow control feedback. The IAB node 300 may record a log related to the flow control feedback in accordance with the setting information set in step S10.

[0079] The log related to flow control feedback may include the following information (B1) to (B6).

[0080] (B1) Information when DL flow control feedback is received. For example, in FIG. 9A, when IAB node 300-P receives DL flow control feedback from IAB node 300-T, the log acquired by IAB node 300-P corresponds to this information.

[0081] Specifically, the log information acquired when DL flow control feedback is received may include the following:

[0082] (B1-1) Identification information of the source node (child node) of the DL flow control feedback. In FIG. 9A, when IAB node 300-P receives DL flow control feedback from IAB node 300-T, the identification information corresponds to the IAB node 300-T's identification information. The identification information may be a BAP address, a C-RNTI (Cell-Radio Network Temporary Identifier), or the like.

[0083] (B1-2) Available buffer size notified by the DL flow control feedback. As described above, the DL flow control feedback includes the available buffer size, so the IAB node 300 may record this as a log. The IAB node 300 may record the buffer size for each BH RLF Channel ID.

[0084] (B1-3) A timestamp when the DL flow control feedback is received. For example, in FIG. 9A, the timestamp measured when IAB node 300-P receives the DL flow control feedback from IAB node 300-T corresponds to the timestamp.

[0085] (B1-4) Radio conditions at the time of receiving the DL flow control feedback. For example, in FIG. 9A, the radio conditions measured by IAB node 300-P when receiving the DL flow control feedback from IAB node 300-T correspond to the radio conditions. The radio conditions may be expressed by RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), SINR (Signal to Interference and Noise Ratio), etc.

[0086] The IAB node 300 may record at least one of (B1-1) to (B1-4) in a memory as a log.

[0087] (B2) Information when UL flow control feedback is received. For example, in FIG. 9B, when IAB node 300-C receives UL flow control feedback from IAB node 300-T, the log acquired by IAB node 300-C corresponds to this information.

[0088] Specifically, the log information acquired when UL flow control feedback is received may include the following:

[0089] (B2-1) Identification information of the source node (parent node) of the UL flow control feedback. In FIG. 9(B), when the IAB node 300-C receives the UL flow control feedback from the IAB node 300-T, the identification information of the IAB node 300-T corresponds to the identification information. The identification information may be a BAP address, a cell ID, a gNB ID, or the like.

[0090] (B2-2) Available buffer size notified by the UL flow control feedback. For example, the available buffer size included in the UL flow control feedback may be used as the buffer size. The IAB node 300-C may record the buffer size for each BH RLF Channel ID.

[0091] (B2-3) A timestamp when the UL flow control feedback is received. For example, in FIG. 9B, when the IAB node 300-C receives the UL flow control feedback from the IAB node 300-T, the timestamp measured by the IAB node 300-C corresponds to the timestamp.

[0092] (B2-4) Radio conditions at the time of receiving the UL flow control feedback. For example, in FIG. 9(B), the radio conditions measured by IAB node 300-C when receiving the UL flow control feedback from IAB node 300-T correspond to the radio conditions. The radio conditions may be expressed by RSRP, RSRQ, SINR, etc.

[0093] The IAB node 300 may record at least one of (B2-1) to (B2-4) in a memory as a log.

[0094] Additionally, (B1) and (B2) may correspond to second information collected by the IAB node 300 when it receives a flow control feedback message.

[0095] (B3) Information when DL flow control feedback is transmitted. For example, in FIG. 9A, when IAB node 300-T transmits DL flow control feedback to IAB node 300-P, the log acquired by IAB node 300-T corresponds to this information.

[0096] Specifically, the log information acquired when DL flow control feedback is transmitted may include the following:

[0097] (B3-1) Identification information of the destination node (parent node) of the DL flow control feedback. In FIG. 9(A), when the IAB node 300-T transmits DL flow control feedback to the IAB node 300-P, the identification information corresponds to the identification information of the destination IAB node 300-P. The identification information may be a BAP address, a cell ID, a gNB ID, or the like.

[0098] (B3-2) Its own available buffer size (Available Buffer Size). For example, the available buffer size included in the DL flow control feedback may be used as the buffer size. The IAB node 300-T may record the buffer size for each BH RLF Channel ID.

[0099] (B3-3) A timestamp when the DL flow control feedback is transmitted. For example, in FIG. 9A, the timestamp measured when IAB node 300-T transmits DL flow control feedback to IAB node 300-P corresponds to the timestamp.

[0100] (B3-4) Radio conditions at the time of transmitting the DL flow control feedback. For example, in FIG. 9A, the radio conditions measured when IAB node 300-T transmits DL flow control feedback to IAB node 300-P correspond to the radio conditions. The radio conditions may be expressed by RSRP, RSRQ, SINR, etc.

[0101] The IAB node 300 may record at least one of (B3-1) to (B3-4) in a memory as a log.

[0102] (B4) Information when UL flow control feedback is transmitted. For example, in FIG. 9B, when IAB node 300-T transmits UL flow control feedback to IAB node 300-C, the log acquired by IAB node 300-T corresponds to this information.

[0103] Specifically, the log information acquired when UL flow control feedback is sent may include the following:

[0104] (B4-1) Identification information of the destination node (child node) of the UL flow control feedback. In FIG. 9(B), when IAB node 300-T transmits UL flow control feedback to IAB node 300-C, the identification information corresponds to the identification information of the destination IAB node 300-C. The identification information may be a BAP address, a C-RNTI, or the like.

[0105] (B4-2) Its own available buffer size (Available Buffer Size). For example, the available buffer size included in the UL flow control feedback may be used as the buffer size. The IAB node 300-T may record the buffer size for each BH RLF Channel ID.

[0106] (B4-3) A timestamp when the UL flow control feedback is transmitted. For example, in FIG. 9B, the timestamp measured when IAB node 300-T transmits the UL flow control feedback to IAB node 300-C corresponds to the timestamp.

[0107] (B4-4) Radio conditions at the time of transmitting the UL flow control feedback. For example, in FIG. 9(B), the radio conditions may correspond to the radio conditions measured when IAB node 300-T transmits the UL flow control feedback to IAB node 300-C. The radio conditions may be expressed by RSRP, RSRQ, SINR, etc.

[0108] The IAB node 300 may record at least one of (B4-1) to (B4-4) in a memory as a log.

[0109] Also, (B3) and (B4) may correspond to the first information collected when the IAB node 300 sends flow control feedback.

[0110] (B5) In the case of periodic measurement, the following information may be regularly recorded as a log.

[0111] (B5-1) Own available buffer size. The buffer size may be recorded for each BH RLF Channel ID.

[0112] (B5-2)Timestamp.

[0113] (B5-3) Radio Conditions The radio conditions may be expressed by RSRP, RSRQ, SINR, and the like.

[0114] The IAB node 300 may record at least one of (B5-1) to (B5-3) as a log.

[0115] (B6) As other information, the identifier of the source node when the IAB node 300 receives the flow control poll may be recorded as a log. The identifier may be a BAP address, a C-RNTI, a cell ID, or a gNB ID. In addition, a timestamp and / or radio conditions when the IAB node 300 receives the flow control poll may be recorded as a log.

[0116] Note that the above (B1) to (B6) may be processed as statistical information. For example, the number of times an IAB node 300 receives flow control feedback from other IAB nodes may be recorded as a log. Also, the number of times an IAB node 300 transmits flow control feedback to other IAB nodes may be recorded as a log. The number of times of reception and the number of times of transmission may be the number of times within a certain period of time. The certain period of time may be set by the donor node 200.

[0117] Returning to FIG. 10, in step S12, the IAB node 300 transmits the log to the donor node 200.

[0118] First, when the setting information is set in step S10, the IAB node 300 transmits a log to the donor node 200 in accordance with the setting information. For example, when a report trigger condition is set as the setting information, the IAB node 300 transmits the recorded log to the donor node 200 in accordance with the report trigger condition. Note that when the report trigger condition is set, the IAB node 300 may immediately transmit the acquired log to the donor node 200 without recording it in memory (or after recording it in memory).

[0119] Second, the IAB node 300 may transmit the recorded log to the donor node 200 in response to an instruction (inquiry message) from the donor node 200.

[0120] The IAB-MT of the IAB node 300 may transmit the log by transmitting an RRC message including the log to the CU of the donor node 200. The IAB-DU of the IAB node 300 may transmit the log by transmitting an F1AP message including the log to the CU of the donor node 200.

[0121] In response to receiving the log, the donor node 200 may perform a process of changing the routing settings for the IAB node 300. This change can, for example, reduce congestion between the IAB nodes 300 and further optimize the topology.

[0122] [Second embodiment] Next, a second embodiment will be described.

[0123] In the first embodiment, a log collected when transmitting and / or receiving flow control feedback has been described. In the second embodiment, a log collected when transmitting and / or receiving Type 2 BH RLF Indication will be described.

[0124] FIG. 11 is a diagram illustrating an example of the configuration of a cellular communication system 1 according to the second embodiment.

[0125] As shown in FIG. 11, the cellular communication system 1 includes an IAB node 300-T, a parent node 300-P, a child node 300-C, and a node 500.

[0126] Parent node 300-P is the parent node of IAB node 300-T and is also an IAB node. Child node 300-C is the child node of IAB node 300-T and is also an IAB node. Furthermore, node 500 is the further parent node of parent node 300-P and is either an IAB node 300 or a donor node 200.

[0127] Here, assume that a BH RLF (Radio Link Failure) occurs in parent node 300-P. A BH RLF is a type of line failure. FIG. 11 shows an example in which a BH RLF (hereinafter sometimes referred to as "RLF") occurs in the BH link between parent node 300-P and node 500.

[0128] When the IAB-MT of parent node 300-P detects a BH RLF, the IAB-DU of parent node 300-P transmits a Type 2 BH RLF Indication (hereinafter sometimes referred to as a "Type 2 Indication") to IAB node 300-T. The Type 2 Indication is an example of a recovery attempt notification indicating that a recovery attempt is being made for the RLF.

[0129] Here, for example, it is assumed that when the IAB node 300-T detects an RLF in its own BH link, the IAB-DU of the IAB node 300-T transmits an RRC reestablishment request to the CU of the donor node 200 upon detecting the RLF. In this case, the donor node 200 can detect that an RLF has occurred in the IAB node 300-T by receiving the RRC reestablishment request.

[0130] Also, for example, it is assumed that when the IAB node 300-T detects RLF in its own BH link, the IAB-DU of the IAB node 300-T transmits an RLF report to the CU of the donor node 200. In this case, the RLF report for MDT in particular includes the latest radio measurement results of the serving cell and neighboring cells. Therefore, by receiving the RLF report, the donor node 200 can detect in which cell the RLF has occurred.

[0131] However, even if the IAB node 300-T receives the Type 2 Indication, it does not detect its own RLF, as shown in Fig. 11. Therefore, the IAB node 300-T cannot transmit an RRC re-establishment request or an RLF report.

[0132] On the other hand, as shown in Fig. 11, there are cases where the parent node 300-P transmits an RRC re-establishment request or an RLF report using its own RLF. In this case, the donor node 200 can predict that the parent node 300-P has transmitted a Type 2 Indication to its child node (IAB node 300-T) by receiving the RRC re-establishment request, the RLF report, or the like.

[0133] However, if IAB node 300-T transmits the Type 2 Indication received from parent node 300-P to child node 300-C of IAB node 300-T, donor node 200 cannot recognize this fact. Furthermore, donor node 200 cannot recognize that child node 300-C has received the Type 2 Indication transmitted from parent node 300-P of IAB node 300-T.

[0134] Here, the transmission of the Type 2 Indication received by IAB node 300-T from parent node 300-P to child node 300-C is called propagation of the Type 2 Indication. The transmission of the Type 2 Indication from child node 300-C to a further child node of child node 300-C is also propagation.

[0135] That is, the donor node 200 cannot know whether or not the Type 2 Indication has been propagated.

[0136] Furthermore, in the mobile IAB that is scheduled to be introduced in the future, the parent-child relationships between nodes within or between topologies will change from moment to moment as the IAB nodes 300 move. In the mobile IAB, it is expected that there will be cases where it will become even more difficult to grasp the propagation of Type 2 Indication.

[0137] Therefore, in the second embodiment, the IAB node 300-T transmits to the donor node 200 the logs collected when transmitting and / or receiving a Type 2 Indication. Specifically, first, the relay node (e.g., the IAB node 300-T) transmits to the donor node (e.g., the donor node 200) the third information collected when the relay node (e.g., the parent node 300-P) receives a notification (e.g., a Type 2 Indication) related to a backhaul failure, and the fourth information collected when the relay node transmits the notification to a child node (e.g., the child node 300-C) of the relay node. Second, the donor node receives the third information and the fourth information.

[0138] This allows the donor node 200 to acquire not only the third information but also the fourth information, thereby enabling topology optimization.

[0139] (Example of operation according to the second embodiment) FIG. 12 is a diagram illustrating an example of operation according to the second embodiment.

[0140] As shown in FIG. 12, in step S20, the IAB node 300-T starts the process.

[0141] In step S21, the IAB node 300-T receives a Type 2 Indication from the parent node 300-P. At this time, the IAB node 300-T acquires a log related to the reception of the Type 2 Indication and records it in memory. At least one of the following pieces of information (C1) to (C5) is recorded as information in the log.

[0142] (C1) Information indicating that a Type 2 Indication has been received.

[0143] (C2) Identification information of the sender (parent node) of the Type 2 Indication. For example, in the example of FIG. 11, when IAB node 300-T receives Type 2 Indication from parent node 300-P, the identification information is the identification information of parent node 300-P. Also, for example, in the example of FIG. 11, when child node 300-C receives Type 2 Indication from IAB node 300-T, the identification information is the identification information of IAB node 300-T. The identification information may be a cell ID, a BAP address, or the like.

[0144] (C3) Information indicating whether propagation has been performed upon reception of the Type 2 Indication. That is, information indicating whether reception of the Type 2 Indication is due to propagation is recorded as a log. For example, in the example of FIG. 11, when the IAB node 300-T receives a Type 2 Indication from the parent node 300-P, the IAB node 300-T records, as a log, information indicating that propagation has not been performed, because the Type 2 Indication was received due to the BH RLF of the parent node 300-P. Also, in the example of FIG. 11, when the child node 300-C receives a Type 2 Indication transmitted (or propagated) from the IAB node 300-T, the child node 300-C records, as a log, information indicating that propagation has been performed.

[0145] (C4) Time Stamp For example, in the example of Fig. 11, the time stamp measured when the IAB node 300-T receives the Type 2 Indication from the parent node 300-P is the time stamp.

[0146] (C5) Location information, specifically, may be at least one of latitude, longitude, altitude, RF fingerprint, collected Wi-fi (registered trademark) information, and collected BT (Blue Tooth (registered trademark)) information.

[0147] Note that the above (C1) to (C5) may be statistically processed. For example, they may be the number of times that the IAB node 300-T receives a Type 2 Indication from the parent node 300-P. The number of times may be a fixed period, and the fixed period may be set by the donor node 200.

[0148] 12, in step S22, the IAB node 300-T transmits a Type 2 Indication to the child node. At this time, the IAB node 300-T acquires a log related to the transmission of the Type 2 Indication and records it in memory. At least one of the following pieces of information (D1) to (D5) is recorded as information in the log.

[0149] (D1) Information indicating that a Type 2 Indication has been sent.

[0150] (D2) Identification information of the destination (child node) of the Type 2 Indication. For example, in the example of Fig. 11, when the IAB node 300-T transmits the Type 2 Indication to the child node 300-C, the identification information is the identification information of the child node 300-C. The identification information may be the C-RNTI, the BAP address, or the like.

[0151] (D3) Information indicating whether the transmission of the Type 2 Indication is due to propagation. That is, information indicating whether the transmission of the Type 2 Indication is due to propagation (or whether the transmission of the Type 2 Indication is due to reception of a Type 2 Indication from a parent node or due to its own BH RLF) is recorded as a log. For example, in the example of FIG. 11, when IAB node 300-T transmits a Type 2 Indication received from parent node 300-P to child node 300-C, it records information indicating that the transmission is due to propagation as a log. On the other hand, for example, in the example of FIG. 11, when parent node 300-P transmits a Type 2 Indication due to its own BH RLF, parent node 300-P records information indicating that the transmission is not due to propagation as a log.

[0152] (D4) Time stamp: For example, in the example of Fig. 11, the time stamp measured when the IAB node 300-T transmits the Type 2 Indication to the child node 300-C is the time stamp.

[0153] (D5) Location information. The specific information may be the same as (C5).

[0154] Note that the above (D1) to (D5) may be statistically processed. For example, they may be the number of times that the IAB node 300-T transmits Type 2 Indication to the child node 300-C. The number of transmissions may be a fixed period, and the fixed period may be set by the donor node 200.

[0155] 12 , in step S23, if a record exists in the memory as a log, the IAB node 300-T may transmit to the donor node 200 a notification that the record exists. For example, the IAB-MT of the IAB node 300-T may transmit to the CU of the donor node 200 an RRC message including information indicating that the record exists. Also, for example, the IAB-DU of the IAB node 300-T may transmit to the CU of the donor node 200 an F1AP message including information indicating that the record exists.

[0156] In step S24, the IAB node 300-T transmits the recorded log to the donor node 200 in response to a request from the donor node 200. The request may also be transmitted by an RRC message, an F1AP message, or the like including the request. The log may also be transmitted by an RRC message, an F1AP message, or the like including the information recorded as the log.

[0157] The information on the log that the IAB node 300-T acquires or collects when receiving a Type 2 Indication (step S21) may correspond to the third information. Also, the information on the log that the IAB node 300-T acquires or collects when transmitting a Type 2 Indication (step S22) may correspond to the fourth information. The IAB node 300-T transmits the third information and the fourth information in step S24.

[0158] Then, in step S25, the IAB node 300-T ends the series of processes.

[0159] (Modification of the second embodiment) In the second embodiment, the Type 2 Indication has been described. For example, as a modified example, a Type 3 BH RLF Indication (hereinafter, sometimes referred to as a "Type 3 Indication") may be used instead of the Type 2 Indication. The Type 3 Indication is a recovery notification indicating recovery from a BH RLF. That is, when the IAB node 300-T receives a Type 3 Indication from the parent node 300-P, the IAB node 300-T may record at least one of (C1) to (C5) as a log. Furthermore, when the IAB node 300-T transmits a Type 3 Indication to the child node 300-C, the IAB node 300-T may record at least one of (D1) to (D5) as a log.

[0160] As a modified example, a Type 1 BH RLF Indication (hereinafter, sometimes referred to as a "Type 1 Indication") may be used instead of a Type 2 Indication. The Type 1 Indication is an example of a failure occurrence notification indicating that a BH RLF has occurred. This is because the IAB node 300 immediately performs a recovery operation from the failure when a BH RLF occurs, and therefore, it is possible to regard the Type 2 Indication and the Type 1 Indication as the same.

[0161] Furthermore, in the second embodiment, an example has been described in which the IAB node 300-T records information in memory as a log and transmits the recorded information to the donor node 200. For example, when the IAB node 300-T receives a Type 2 Indication as an event trigger, the IAB node 300-T may collect information as a log and immediately transmit the collected information to the donor node 200 without recording it in memory (or after recording it in memory). Also, for example, when the IAB node 300-T transmits a Type 2 Indication as an event trigger, the IAB node 300-T may collect information as a log and immediately transmit the collected information to the donor node 200 without recording it in memory (or after recording it in memory). Such settings may be performed by the donor node 200.

[0162] [Other embodiments] A program may be provided that causes a computer to execute each process performed by the UE 100 or the gNB 200. The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0163] In addition, circuits that execute each process performed by UE100 or gNB200 may be integrated, and at least a part of UE100 or gNB200 may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0164] As used in this disclosure, the terms "based on" and "depending on" do not mean "based only on" or "depending only on," unless expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "based only on" and "at least in part on." Furthermore, "obtain" may mean obtaining information from stored information, obtaining information from information received from another node, or obtaining information by generating the information. The terms "include," "comprise," and variations thereof do not mean including only the listed items, but may also mean including only the listed items or including additional items in addition to the listed items. Furthermore, as used in this disclosure, the term "or" is not intended to mean an exclusive or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, reference to first and second elements does not imply that only two elements may be employed therein or that the first element must precede the second element in some manner. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0165] Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes can be made without departing from the scope of the invention. Furthermore, it is also possible to combine all or part of each embodiment within a consistent range.

[0166] This application claims priority to Japanese Patent Application No. 2021-128614 (filed August 4, 2021), the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0167] 1: Cellular communication system 10:5GC 100:UE 110: Wireless communication unit 120: Control unit 200 (200-1, 200-2): gNB (donor node) 210: Wireless communication unit 220: Network communication department 230: Control unit 300 (300-1, 300-2, 300-P, 300-T, 300-C): IAB node 310: wireless communication unit 320: Control unit

Claims

1. A communication control method for use in a cellular communication system, comprising: receiving, by the wireless node, configuration information from the network node for recording log information relating to a predetermined feedback message; transmitting, to the network node, the predetermined feedback message including the log information collected up until the time of transmitting the predetermined feedback message in accordance with the setting information, the setting information includes first time information for triggering transmission of the predetermined feedback message; The log information includes second time information different from the first time information and information about an available buffer size. Communication control method.

2. A wireless node of a cellular communication system, comprising: a receiving unit for receiving configuration information for recording log information relating to a predetermined feedback message from a network node; a transmitter configured to transmit the predetermined feedback message including the log information collected up until the predetermined feedback message is transmitted to the network node in accordance with the setting information, the setting information includes first time information for triggering transmission of the predetermined feedback message; The log information includes second time information different from the first time information and information about an available buffer size. Wireless node.

3. 1. A cellular communication system having a radio node and a network node, the wireless node receives configuration information for recording log information regarding a predetermined feedback message from the network node; the wireless node transmits to the network node the predetermined feedback message including the log information collected up until the time of transmitting the predetermined feedback message in accordance with the setting information; the setting information includes first time information for triggering transmission of the predetermined feedback message; The log information includes second time information different from the first time information and information about an available buffer size. Cellular communication systems.

4. 1. A chipset for a wireless node in a cellular communication system, comprising: receiving configuration information from a network node for recording log information relating to a predetermined feedback message; transmitting the predetermined feedback message to the network node according to the setting information, the predetermined feedback message including the log information collected up until the time of transmitting the predetermined feedback message; the setting information includes first time information for triggering transmission of the predetermined feedback message; The log information includes second time information different from the first time information and information about an available buffer size. Chipset.

5. In a wireless node of a cellular communication system, receiving configuration information from a network node for recording log information relating to a predetermined feedback message; transmitting, to the network node, the predetermined feedback message including the log information collected up until the time of transmitting the predetermined feedback message in accordance with the setting information; the setting information includes first time information for triggering transmission of the predetermined feedback message; The log information includes second time information different from the first time information and information about an available buffer size. program.

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