WO2022085696A1 - 通信制御方法 - Google Patents

通信制御方法 Download PDF

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Publication number
WO2022085696A1
WO2022085696A1 PCT/JP2021/038658 JP2021038658W WO2022085696A1 WO 2022085696 A1 WO2022085696 A1 WO 2022085696A1 JP 2021038658 W JP2021038658 W JP 2021038658W WO 2022085696 A1 WO2022085696 A1 WO 2022085696A1
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WO
WIPO (PCT)
Prior art keywords
node
iab
relay node
failure
notification
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Ceased
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PCT/JP2021/038658
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English (en)
French (fr)
Japanese (ja)
Inventor
真人 藤代
ヘンリー チャン
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kyocera Corp
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Kyocera Corp
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Filing date
Publication date
Application filed by Kyocera Corp filed Critical Kyocera Corp
Priority to CN202180086330.5A priority Critical patent/CN116671149B/zh
Priority to JP2022557567A priority patent/JP7618689B2/ja
Priority to EP21882837.4A priority patent/EP4224902B1/en
Publication of WO2022085696A1 publication Critical patent/WO2022085696A1/ja
Priority to US18/303,808 priority patent/US20230328629A1/en
Anticipated expiration legal-status Critical
Priority to JP2024048615A priority patent/JP7658003B2/ja
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/34—Modification of an existing route
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/28—Routing or path finding of packets in data switching networks using route fault recovery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/22—Alternate routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/04—Arrangements for maintaining operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/00837—Determination of triggering parameters for hand-off
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/34—Reselection control
    • H04W36/36—Reselection control by user or terminal equipment
    • H04W36/362—Conditional handover
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/02—Terminal devices
    • H04W88/04—Terminal devices adapted for relaying to or from another terminal or user

Definitions

  • the present invention relates to a communication control method used in a cellular communication system.
  • IAB Integrated Access and Backhaul
  • One or more relay nodes intervene in the communication between the base station and the user device, and relay the communication.
  • the communication control method is the communication control method used in the cellular communication system.
  • the communication control method is that the relay node that detects the occurrence of a failure in the backhaul link between the relay node and the parent node of the relay node sends a notification instructing the execution of conditional handover and communication.
  • the device has to receive the notification.
  • the communication control method is the communication control method used in the cellular communication system.
  • the first relay node that has detected the occurrence of a failure in the backhaul link between the first relay node and the parent node of the first relay node indicates the occurrence of the failure.
  • the occurrence notification includes transferability information indicating whether or not to transfer the failure occurrence notification, and is to be transmitted to the second relay node.
  • the second relay node transfers the failure occurrence notification received from the first relay node according to the transfer possibility information, or the second relay node receives the notification from the second relay node. It has to not forward the failure notification.
  • the communication control method is the communication control method used in the cellular communication system.
  • the first relay node transmits a failure occurrence notification indicating that a failure has occurred in the backhaul link, or a recovery failure notification indicating that recovery from the failure has failed in the backhaul link.
  • the first request requesting the change of the route priority is transmitted to the second relay node.
  • the second relay node reaches the fourth relay node from the second relay node via the third relay node in response to the reception of the first request. It has the priority of one route and / or the priority of a second route from the second relay node to the fourth relay node via the fifth relay node.
  • the communication control method includes that the second relay node transmits a packet according to the changed priority of the first route and / or the changed priority of the second route.
  • the communication control method is the communication control method used in the cellular communication system.
  • the second relay node receives a failure occurrence notification indicating that a failure has occurred in the backhaul link from the first relay node, and the second relay node has the failure occurrence.
  • the main path setting is deactivated, and the alternative path setting for the main path is activated.
  • FIG. 1 is a diagram showing a configuration example of a cellular communication system according to an embodiment.
  • FIG. 2 is a diagram showing the relationship between the IAB node, the parent node (Parent nodes), and the child node (Child nodes).
  • FIG. 3 is a diagram showing a configuration example of a gNB (base station) according to an embodiment.
  • FIG. 4 is a diagram showing a configuration example of an IAB node (relay node) according to an embodiment.
  • FIG. 5 is a diagram showing a configuration example of a UE (user device) according to an embodiment.
  • FIG. 6 is a diagram showing an example of a protocol stack for RRC connection and NAS connection of IAB-MT.
  • FIG. 7 is a diagram showing an example of a protocol stack for the F1-U protocol.
  • FIG. 8 is a diagram showing an example of a protocol stack for the F1-C protocol.
  • FIG. 9 is a diagram showing a configuration example of the cellular communication system according to the first embodiment.
  • FIG. 10 is a diagram showing an operation example of the first embodiment.
  • FIG. 11 is a diagram showing a configuration example of the cellular communication system according to the third embodiment.
  • FIG. 12 is a diagram showing an operation example of the third embodiment.
  • FIG. 13 is a diagram showing a configuration example of the cellular communication system according to the fourth embodiment.
  • FIG. 14 is a diagram showing an operation example of the fourth embodiment.
  • FIG. 15 is a diagram showing an operation example of the fifth embodiment.
  • FIG. 16 is a diagram showing the types of BH RLF notifications.
  • FIG. 17 is a diagram showing transmission options of the extended BH RLF indication.
  • FIG. 18 shows a specific solution for avoiding re-establishment to descendant nodes.
  • FIG. 19 is a diagram showing a comparison of the mechanism of lossless distribution of UL data in the case of hop-by-hop RLCARQ.
  • FIG. 20 is a diagram showing options of “C) Introducing UL status distribution”.
  • FIG. 21 is a diagram illustrating RAN2 signaling problems that can occur with IAB node movement between donors.
  • the cellular communication system 1 is a 5G system of 3GPP.
  • the wireless access system in the cellular communication system 1 is NR (New Radio), which is a 5G wireless access system.
  • NR New Radio
  • LTE Long Term Evolution
  • the cellular communication system 1 may be applied to future cellular communication systems such as 6G.
  • FIG. 1 is a diagram showing a configuration example of a cellular communication system 1 according to an embodiment.
  • the cellular communication system 1 includes a 5G core network (5GC) 10, a user device (UE: User Equipment) 100, and a base station device (hereinafter, may be referred to as a “base station”) 200. It has -1,200-2, and IAB nodes 300-1,300-2.
  • the base station 200 may be referred to as a gNB.
  • the base station 200 may be an LTE base station (that is, an eNB).
  • base stations 200-1 and 200-2 may be referred to as gNB200 (or base station 200), and IAB nodes 300-1 and 300-2 may be referred to as IAB node 300, respectively.
  • the 5GC10 has an AMF (Access and Mobility Management Function) 11 and an UPF (User Plane Function) 12.
  • the AMF 11 is a device that performs various mobility controls and the like for the UE 100.
  • the AMF 11 manages information on the area in which the UE 100 is located by communicating with the UE 100 using NAS (Non-Access Stratum) signaling.
  • the UPF 12 is a device that controls the transfer of user data and the like.
  • Each gNB 200 is a fixed wireless communication node and manages one or a plurality of cells.
  • Cell is used as a term to indicate the smallest unit of wireless communication area.
  • Cell may be used as a term to indicate a function or resource for wireless communication with the UE 100.
  • One cell belongs to one carrier frequency. In the following, cells and base stations may be used without distinction.
  • Each gNB200 is interconnected with the 5GC10 via an interface called an NG interface.
  • FIG. 1 illustrates two gNB200-1 and gNB200-2 connected to 5GC10.
  • Each gNB 200 may be divided into an aggregate unit (CU: Central Unit) and a distributed unit (DU: Distributed Unit).
  • 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 the DU, and includes the F1-C protocol, which is a control plane protocol, and the F1-U protocol, which is a user plane protocol.
  • the cellular communication system 1 supports IAB that enables wireless relay of NR access by using NR in the backhaul.
  • the donor gNB200-1 is a terminal node of the NR backhaul on the network side and is a donor base station having an additional function to support IAB.
  • the backhaul can be multi-hop through multiple hops (ie, multiple IAB nodes 300).
  • FIG. 1 an example in which the IAB node 300-1 wirelessly connects to the donor gNB200-1, the IAB node 300-2 wirelessly connects to the IAB node 300-1, and the F1 protocol is transmitted in two backhaul hops. Is shown.
  • the UE 100 is a mobile wireless communication device that performs wireless communication with a cell.
  • the UE 100 may be any device as long as it is a device that performs wireless communication with the gNB 200 or the IAB node 300.
  • the UE 100 is a mobile phone terminal, a tablet terminal, a notebook PC, a sensor or a device provided in the sensor, a vehicle or a device provided in the vehicle, a flying object or a device provided in the flying object.
  • the UE 100 wirelessly connects to the IAB node 300 or 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 gNB200-1 via the IAB node 300-2 and the IAB node 300-1.
  • FIG. 2 is a diagram showing the relationship between the IAB node 300, the parent node (Parent nodes), and the child node (Child nodes).
  • each IAB node 300 has an IAB-DU corresponding to a base station functional unit and an IAB-MT (Mobile Termination) corresponding to a user equipment functional unit.
  • IAB-DU corresponding to a base station functional unit
  • IAB-MT Mobile Termination
  • the adjacent node (that is, the upper node) on the NR Uu radio interface of the IAB-MT is called the parent node.
  • the parent node is the parent IAB node or the DU of the donor gNB200.
  • 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 the IAB nodes 300P1 and 300P2. The direction toward the parent node is called upstream. Seen from the UE 100, the upper node of the UE 100 may correspond to the parent node.
  • the adjacent node (that is, the lower node) on the NR Uu access interface of the IAB-DU is called a child node.
  • the IAB-DU manages the cell in the same manner as the gNB200.
  • the IAB-DU terminates the NR Uu radio interface to the UE 100 and lower IAB nodes.
  • the IAB-DU supports the F1 protocol to the CU of donor gNB200-1.
  • FIG. 2 shows an example in which the child node of the IAB node 300 is the IAB node 300C1-300C3, the UE 100 may be included in the child node of the IAB node 300.
  • the direction toward the child node is called downstream.
  • FIG. 3 is a diagram showing a configuration example of gNB 200.
  • the gNB 200 has a wireless communication unit 210, a network communication unit 220, and a control unit 230.
  • 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 reception unit 211 and a transmission unit 212.
  • the receiving unit 211 performs various receptions under the control of the control unit 230.
  • the receiving unit 211 includes an antenna, converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal), and outputs the radio signal to the control unit 230.
  • the transmission unit 212 performs various transmissions under the control of the control unit 230.
  • the transmission unit 212 includes an antenna, converts (up-converts) a baseband signal (transmission signal) output by the control unit 230 into a radio signal, and transmits the baseband signal (transmission signal) from the antenna.
  • the network communication unit 220 performs wired communication (or wireless communication) with 5GC10 and wired communication (or wireless communication) with other adjacent gNB200.
  • the network communication unit 220 has a reception unit 221 and a transmission 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 transmission unit 222 performs various transmissions under the control of the control unit 230.
  • the transmission unit 222 transmits the transmission signal output by the control unit 230 to the outside.
  • the control unit 230 performs various controls on 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 a program executed by the processor and information used for processing by the processor.
  • the processor may include a baseband processor and a CPU (Central Processing Unit).
  • the baseband processor modulates / demodulates and encodes / decodes the baseband signal.
  • the CPU executes a program stored in the memory to perform various processes.
  • the processor performs processing of each layer described later. Further, the control unit 230 may perform each process in the gNB 200 in each of the following embodiments.
  • FIG. 4 is a diagram showing a configuration example of the IAB node 300.
  • the IAB node 300 has a wireless communication unit 310 and a control unit 320.
  • the IAB node 300 may have a plurality of wireless communication units 310.
  • 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.
  • the wireless communication unit 310 has a receiving unit 311 and a transmitting unit 312.
  • the receiving unit 311 performs various receptions under the control of the control unit 320.
  • the receiving unit 311 includes an antenna, converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal), and outputs the radio signal to the control unit 320.
  • the transmission unit 312 performs various transmissions under the control of the control unit 320.
  • the transmission unit 312 includes an antenna, converts (up-converts) a baseband signal (transmission signal) output by the control unit 320 into a radio signal, and transmits the baseband signal (transmission signal) from the antenna.
  • the control unit 320 performs various controls on 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 a program executed by the processor and information used for processing by the processor.
  • the processor may include a baseband processor and a CPU.
  • the baseband processor modulates / demodulates and encodes / decodes the baseband signal.
  • the CPU executes a program stored in the memory to perform various processes.
  • the processor performs processing of each layer described later. Further, the control unit 320 may perform each process on the IAB node 300 in each of the following embodiments.
  • FIG. 5 is a diagram showing the configuration of the UE 100. As shown in FIG. 5, the UE 100 has a wireless communication unit 110 and a control unit 120.
  • the wireless communication unit 110 performs wireless communication on the access link, that is, wireless communication with the gNB 200 and wireless communication with the IAB node 300. Further, the wireless communication unit 110 may perform wireless communication on the side link, that is, wireless communication with another UE 100.
  • the wireless communication unit 110 has a reception unit 111 and a transmission unit 112.
  • the receiving unit 111 performs various receptions under the control of the control unit 120.
  • the receiving unit 111 includes an antenna, converts (down-converts) a radio signal received by the antenna into a baseband signal (received signal), and outputs the radio signal to the control unit 120.
  • the transmission unit 112 performs various transmissions under the control of the control unit 120.
  • the transmission unit 112 includes an antenna, converts (up-converts) a baseband signal (transmission signal) output by the control unit 120 into a radio signal, and transmits the baseband signal (transmission signal) from the antenna.
  • the control unit 120 performs various controls on 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 a program executed by the processor and information used for processing by the processor.
  • the processor may include a baseband processor and a CPU.
  • the baseband processor modulates / demodulates and encodes / decodes the baseband signal.
  • the CPU executes a program stored in the memory to perform various processes.
  • the processor performs processing of each layer described later.
  • the control unit 130 may perform each process in the UE 100 in each of the following embodiments.
  • FIG. 6 is a diagram showing an example of a protocol stack for RRC connection and NAS connection of IAB-MT.
  • the IAB-MT of the IAB node 300-2 includes a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, and a PDCP (Packet Data Control Protocol). It has a layer, an RRC (Radio Response Control) layer, and a NAS (Non-Access Stratum) layer.
  • PHY physical
  • MAC Medium Access Control
  • RLC Radio Link Control
  • PDCP Packet Data Control Protocol
  • It has a layer, an RRC (Radio Response Control) layer, and a NAS (Non-Access Stratum) layer.
  • RRC Radio Response Control
  • NAS Non-Access Stratum
  • the PHY layer performs coding / 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 the IAB node 300-2 and the PHY layer of the IAB-DU of the IAB node 300-1 via a physical channel.
  • the MAC layer performs data priority control, retransmission processing by hybrid ARQ (HARQ), random access procedure, and the like. Data and control information are transmitted between the MAC layer of the IAB-MT of the IAB node 300-2 and the MAC layer of the IAB-DU of the IAB node 300-1 via the transport channel.
  • the MAC layer of the IAB-DU includes a scheduler. The scheduler determines the transport format (transport block size, modulation / coding method (MCS)) of the upper and lower links and the allocated resource block.
  • MCS modulation / coding method
  • the RLC layer transmits data to the receiving RLC layer by using the functions of the MAC layer and the PHY layer. Data and control information are transmitted between the RLC layer of the IAB-MT of the IAB node 300-2 and the RLC layer of the IAB-DU of the IAB node 300-1 via a logical channel.
  • the PDCP layer performs header compression / decompression and encryption / decryption. Data and control information are transmitted via the radio bearer between the PDCP layer of the IAB-MT of the IAB node 300-2 and the PDCP layer of the donor gNB200.
  • the RRC layer controls logical channels, transport channels, and physical channels according 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 gNB200. If there is an RRC connection with the donor gNB200, the IAB-MT is in the RRC connected state. If there is no RRC connection with the donor gNB200, the IAB-MT is in the RRC idle state.
  • the NAS layer located 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 AMF11.
  • FIG. 7 is a diagram showing a protocol stack related to the F1-U protocol.
  • FIG. 8 is a diagram showing a protocol stack for the F1-C protocol.
  • the donor gNB200 is divided into CU and DU.
  • each of the IAB-MT of the IAB node 300-2, the IAB-DU of the IAB node 300-1 and the IAB-MT of the IAB node 300-1 and the DU of the donor gNB200 are above the RLC layer. It has a BAP (Backhaul Adjustment Protocol) layer as a 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, which enables routing in multiple hops.
  • the PDU (Protocol Data Unit) of the BAP layer is transmitted by the backhaul RLC channel (BH NR RLC channel).
  • the backhaul RLC channel BH NR RLC channel.
  • the protocol stack of the F1-C protocol has an F1AP layer and an SCTP (Stream Control Transmission Protocol) layer instead of the GTP-U layer and the UDP layer shown in FIG. 7.
  • SCTP Stream Control Transmission Protocol
  • FIG. 9 is a diagram showing a configuration example of the cellular communication system 1 according to the first embodiment.
  • the cellular communication system 1 shown in FIG. 9 includes a node 500, an IAB node 300-T, an IAB node 300-C, and a UE 100.
  • the IAB node 300-C and the UE 100 may be communication devices.
  • the node 500 is a parent node of the IAB node 300-T, and is a gNB200 (or a donor node; hereinafter, “gNB200” may be referred to as a “donor node”) or an IAB node 300 (parent IAB node).
  • the IAB-MT of the IAB node 300-T has established a backhaul link (BH link) # 1 with the node 500.
  • the IAB-MT of the IAB node 300-T is in the RRC connected state.
  • the IAB node 300-C is a child node (child IAB node) of the IAB node 300-T.
  • the IAB-MT of the IAB node 300-C has established a BH link # 2 with the IAB node 300-T.
  • the IAB-MT of the IAB node 300-C is in the RRC connected state.
  • the IAB-MT of the IAB node 300-C may be in the RRC idle state without establishing the BH link # 2 with the IAB node 300-T.
  • the UE 100 has established an access link with the IAB node 300-T.
  • the UE 100 is in the RRC connected state.
  • the UE 100 may be in the RRC idle state without establishing an access link with the IAB node 300-T.
  • the IAB-MT of the IAB node 300-T detects the radio link failure of the BH link # 1 (BH RLF (Radio Link Failure)).
  • the IAB-MT of the IAB node 300-T detects the BH RLF as follows, and performs a recovery trial for recovery from the BH RLF.
  • the IAB-MT of the IAB node 300-T detects an out-of-sync state (out-of-sync) N310 times in a row, it detects a radio problem (radio problem) and starts the timer T310 (). Start). After starting the timer T310, the IAB-MT of the IAB node 300-T stops the timer T310 when the synchronization state (in-sync) is continuously detected N311 times.
  • the IAB-MT of the IAB node 300-T detects the RLF and starts the timer T311 (that is, starts the RRC reestablishment process) when the timer T310 expires without stopping the timer T310. Perform cell selection processing to recover the BH link.
  • the IAB-MT of the IAB node 300-T selects an appropriate cell by the cell selection process, and stops the timer T311 when the BH link is restored for the selected cell.
  • a suitable cell is one that meets at least the minimum radio quality standards.
  • the IAB-MT of the IAB node 300-T transitions to the RRC idle state when the timer T311 expires without succeeding in recovering the BH link.
  • failure to recover from BH RLF after detecting BH RLF (that is, timer T311 has expired) may be referred to as failure of BH link recovery.
  • Type 1 Instruction is an example of a failure occurrence notification indicating that BH RLF has been detected.
  • Type2 Instruction is an example of a failure occurrence notification indicating that recovery from BH RLF is being attempted.
  • Type 1/2 Indication can be transmitted to the IAB-MT and the UE 100 of the IAB node 300-C.
  • Type1 / 2 Instruction is also an example of failure notification.
  • Type3 Inspection is a recovery notification indicating that the IAB node 300-T has recovered from the BH RLF.
  • Type4Indication is an example of a recovery failure notification indicating that the IAB node 300-T has failed to recover from the BH RLF.
  • Each Indication may be included in the BAP Control PDU or MAC CE and transmitted in the BH link. Further, each Instruction may be included in SIB1 and transmitted in the access link.
  • the IAB-MT of the IAB node 300-T detects the BH RLF of the BH link # 1
  • the radio state of the BH link # 2 and the radio state of the access link may be good. Therefore, there is a concern that the IAB node 300-C and the UE 100 may stay in the cell of the IAB node 300-T that has detected the BH RLF.
  • the IAB node 300-T transmits a notification indicating the execution instruction of the conditional handover to at least one of the IAB node 300-C and the UE 100.
  • the relay node that detects the occurrence of a failure in the backhaul link between the relay node and the parent node of the relay node sends a notification instructing the execution of the conditional handover.
  • the communication device receives the notification.
  • Communication devices are, for example, IAB nodes 300-C and UE100. Thereby, for example, when the IAB node 300-T detects the occurrence of a failure in the backhaul link, the IAB node 300-C or the UE 100 can execute a conditional handover to switch the connection to another IAB node. It becomes.
  • conditional handover is a handover executed when one or more handover execution conditions (or trigger conditions) are satisfied.
  • the conditional handover setting includes a candidate cell for the handover and a trigger condition for the handover.
  • the conditional handover setting may include a plurality of combinations of candidate cells and trigger conditions.
  • the conditional handover settings further include the RRC settings corresponding to the candidate cells.
  • the UE 100 reports the measured value of the radio state of the serving cell and / or the adjacent cell to the gNB 200, and based on this report, the gNB 200 determines the handover to the adjacent cell and transmits the handover instruction to the UE 100. .. Therefore, when the radio state of the serving cell is suddenly deteriorated, in general handover, communication may be interrupted before the handover is executed.
  • the conditional handover when the preset trigger condition is satisfied, the handover to the candidate cell corresponding to the trigger condition can be autonomously executed. Therefore, problems such as communication blackout in general handover can be solved.
  • Event A3 is an event in which the radio state of the adjacent cell is better than the radio state of the serving cell by a predetermined amount (predetermined offset) or more.
  • Event A5 is an event in which the radio state of the serving cell is deteriorated from the first threshold value and the radio state of the adjacent cell is better than the second threshold value.
  • FIG. 10 is a diagram showing an operation example according to the first embodiment.
  • the operation example shown in FIG. 10 shows the operation example in the cellular communication system 1 in FIG.
  • the IAB node 300-T shown in FIG. 9 may be referred to as an upper node 300-T
  • the IAB node 300-C may be referred to as a lower node 300-C.
  • step S100 the cellular communication system 1 starts processing.
  • the donor node sets a conditional handover (CHO (Conditional Handover)) for the lower nodes 300-C and the UE 100.
  • the trigger condition included in the conditional handover setting may include "reception of a notification indicating an execution instruction of the conditional handover".
  • the conditional handover may be set by unicast signaling (for example, RRC Reconnection message) from the CU of the donor node to the IAB-DU of the lower node 300-C and the UE 100.
  • unicast signaling for example, RRC Reconnection message
  • the upper node 300-T When the upper node 300-T detects the BH RLF in step S102, the upper node 300-T transmits a notification indicating the execution instruction of the conditional handover to the lower nodes 300-C and the UE 100.
  • the notification indicating the execution instruction of the conditional handover may be included in a message of the BAP layer, for example, a BAP Control PDU (Protocol Data Unit).
  • the execution instruction may be included in MAC CE (MAC Control Element).
  • the IAB-MT of the lower node 300-C connected to the IAB-DU of the upper node 300-T can receive the BAP layer message including the execution instruction from the IAB-DU of the upper node 300-T.
  • the IAB-DU of the upper node 300-T includes the execution instruction in the system information block type 1 (SIB (System Information Block) 1) and transmits the execution instruction.
  • SIB System Information Block
  • the notification in step S102 may be set by the donor node as to whether or not the notification is performed. This can be achieved by the CU of the donor node making such a setting for the IAB-DU of the upper node 300-T by signaling. Alternatively, the higher-level node 300-T may perform step S102 only when the IAB node 300-C or the UE 100 is present under the control. Such a setting may also be made by the CU of the donor node.
  • step S103 when the lower node 300-C receives the notification indicating the execution instruction of the conditional handover, the lower node 300-C executes the conditional handover. In order to satisfy one of the trigger conditions of the conditional handover, "reception of the notification indicating the execution instruction of the conditional handover", the lower node 300-C will execute the handover.
  • RSRP Reference Signal Received Power: reference signal received power
  • the lower node 300-C may apply TTT (Time to Tiger: time trigger) or wait for the execution of the conditional handover for a certain period of time.
  • TTT Time to Tiger: time trigger
  • the lower node 300-C may cancel the trigger condition and does not perform the conditional handover.
  • the TTT may be set by the CU of the donor node in step S101.
  • step 104 the cellular communication system 1 ends a series of processes.
  • Type 1 Instruction there may be "reception of Type 1 Instruction".
  • the lower node 300-C or the UE 100 receives the Type 1 Instruction from the upper node 300-T, so that the trigger condition of the conditional handover is satisfied and the handover is performed.
  • the upper node 300-T detects a failure (BH RLF)
  • the lower node 300-C or the UE 100 performs a handover to another IAB node 300.
  • a trigger condition there may be "reception of Type 2 Instruction”.
  • the lower node 300-C or the UE 100 receives the Type 2 Instruction from the upper node 300-T, so that the trigger condition of the conditional handover is satisfied and the handover is performed.
  • the upper node 300-T is in the recovery operation for the failure (BH RLF)
  • the lower node 300-C or the UE 100 will perform a handover to another IAB node 300.
  • a trigger condition " There may be "Reception of Type 4 Instruction”.
  • the lower node 300-C or the UE 100 receives the Type 4 Instruction from the upper node 300-T, so that the trigger condition of the conditional handover is satisfied and the handover is performed.
  • the upper node 300-T detects a recovery failure due to a failure (BH RLF)
  • the lower node 300-C or the UE 100 performs a handover to another IAB node 300.
  • Such a setting may be made, for example, in step 101 (FIG. 10) of the first embodiment.
  • the CU of the donor node sets a conditional handover in the IAB-DU or UE100 of the lower node 300-C with the reception of Type1, Type2, or Type4 Instruction as a trigger condition.
  • the lower node may start RRC reestablishment (RRC Restabrishment) all at once by receiving Type1 / 2 Instruction.
  • RRC Restabrishment RRC Restabrishment
  • the topology of the IAB node 300 may collapse.
  • all IAB nodes 300 in the topology may transfer RRC re-establishment, etc. even to IAB nodes that do not need to execute RRC re-establishment, etc. by transferring Type1 / 2 Instruction. Further, even if all the IAB nodes 300 execute RRC re-establishment or the like, the connection is disturbed and the signaling does not reach the donor node, so that such processing is not considered to be successful. Further, in the first place, the IAB is performed by the centralized processing by the donor node, and there is a possibility that the IAB may fall into an uncontrollable state from the center.
  • the transfer enable / disable information is included in the Type1 / 2 Instruction.
  • the transfer hop number information is included in the Type1 / 2 Instruction.
  • the first relay node that detects the occurrence of a failure in the backhaul link between the first relay node and the parent node of the first relay node is a failure indicating the occurrence of a failure.
  • the occurrence notification includes transfer availability information indicating whether or not to transfer the failure occurrence notification, and is transmitted to the second relay node.
  • the second relay node transfers the failure occurrence notification received from the first relay node or does not transfer the failure occurrence notification received from the first relay node according to the transfer possibility information.
  • the IAB node 300 can properly transfer the Type 1/2 Indication, and the topology can be quickly recovered and the influence on the entire topology can be minimized.
  • FIG. 11 is a diagram showing a configuration example of the cellular communication system 1 according to the third embodiment.
  • the IAB-MT of the IAB node (or upper node) 300-T detects a failure of the BH link # 1 with the node 500 by the method described in the first embodiment.
  • the IAB-DU of the IAB node 300-T transmits the Type 1 Indication, the Type 2 Indication, or the Type 1/2 Indication including transferability information and the like to the IAB-MT of the IAB node 300-C which is a lower node.
  • the lower node 300-C may or may not transfer the received Instruction to the lower IAB node 300 according to the transfer possibility information and the like included in these Indications.
  • FIG. 12 is a diagram showing an operation example in the third embodiment.
  • step S110 the cellular communication system 1 starts processing.
  • step S111 when the IAB-MT of the IAB node 300-T detects the BH RLF on its own BH link # 1, the IAB-DU of the IAB node 300-T moves to the IAB-MT of the lower node 300-C.
  • Send Type1 Instruction when it is detected that the IAB-MT of the IAB node 300-T has started the recovery operation of the BH RLF at the BH link # 1, the IAB-DU of the IAB node 300-T has the lower node 300-.
  • Type2 Instruction is transmitted to C's IAB-MT. If the IAB-DU of the IAB node 300-T does not distinguish between the Type 1 Indication and the Type 2 Indication, the Type 1/2 Indication is transmitted to the IAB-MT of the lower node 300-C.
  • Type1 Information, Type2 Information, and Type1 / 2 Instruction include the following information.
  • these Indications include the type information (type information) of the Indication.
  • type information indicating that it is Type1 is included.
  • the type information may include the types of these Indications.
  • these Indications include transfer enable / disable information indicating whether or not to transfer this Indication. For example, in the case of "0", transfer is not possible, and in the case of "1", transfer is possible (transfer implementation).
  • the information may include information on whether or not the instruction is transmitted according to the BH RLF of the own IAB node 300.
  • “0” may represent its own BH RLF
  • "1" may represent the BH RLF of the parent node of its own IAB node 300.
  • the IAB node 300-T detects the BH RLC on its own BH link # 1 and transmits the Type 1 Instruction to the lower node 300-C
  • the IAB node 300-T is used as the information.
  • "0" and the lower node 300-C include "1" as the information, and transfer the Type 1 Instruction.
  • the information may include information as to whether or not the instruction is transmitted in response to the instruction from the higher-level node 300-T.
  • the lower node 300-C receives the Type 1 Indication from the upper node 300-T
  • the lower node 300-C further lowers the Type 1 Indication including information indicating that the Type 1 Indication is transmitted in response to the Indication from the upper node 300-T. Transfer to.
  • these Indications may include transfer hop information.
  • transfer hop information For example, in FIG. 11, consider the case where the IAB node 300-T is the highest IAB node on a predetermined topology. In this case, when the IAB-MT of the IAB node 300-T detects the BH RLF, the information includes "0" as the transfer hop number information and transmits the BH RLF. Then, each time a transfer is performed, the number of transfer hops is incremented. Each IAB node 300 includes the incremented number of transfer hops in the Type 1 Instruction and further transfers to a lower node.
  • the upper limit of the number of transfer hops may be set by the CU of the donor node for the IAB-DU (or IAB-MT) of each IAB node 300 by signaling.
  • the IAB-DU of each IAB node 300 compares the transfer hop number information included in each received Instruction with the upper limit value, and transfers or does not transfer the received Instruction according to the comparison result. For example, when the transfer hop number information is the same as the upper limit value, the IAB-DU of the IAB node 300 does not transfer the received Instruction, and when the transfer hop number is smaller than the upper limit value, the received Instruction is transferred.
  • step S112 the lower node 300-C determines whether or not to transfer the received Instruction to the lower IAB node 300 according to the information contained in the received Instruction. Then, the lower node 300-C transfers or does not transfer the received Instruction according to the determination.
  • the IAB-DU of the lower node 300-C does not transfer the received Instruction when "0" is included as the transfer enable / disable information.
  • the IAB-DU of the lower node 300-C transfers the received Instruction to the lower node when "1" is included as the transfer enable / disable information.
  • the Information includes information on the number of transfer hops, it will be as follows. That is, the IAB-DU of the lower node 300-C compares the transfer hop number information included in each received instruction with the upper limit value, and if the transfer hop number information is the same as the upper limit value, does not transfer the received instruction. On the other hand, the IAB-DU of the lower node 300-C transfers the received Instruction when the number of transfer hops is smaller than the upper limit value. Alternatively, when the number of transfer hops exceeds the upper limit, it may be determined that the IAB-DU of the lower node 300-C does not transfer the received Instruction. If the number of transfer hops is the same as or smaller than the upper limit, the IAB-DU of the lower node 300-C may transfer the received Instruction.
  • step S113 the cellular communication system 1 ends a series of processes.
  • the notification indicating the execution instruction of the conditional handover described in the first embodiment may be the transfer target.
  • the IAB node 300-T may transmit the notification including the transfer possibility information or the transfer hop number information.
  • route priority (or route priority) is discussed with respect to IAB.
  • the route priority is, for example, a priority in which a plurality of routes (or routes, hereinafter may be referred to as "routes") are set for the same destination in IAB, and are set for each route. Is.
  • FIG. 13 is a diagram showing an example of the cellular communication system 1 in the fourth embodiment.
  • the IAB node 300-T is the upper node
  • the IAB node 300-C is the lower node.
  • the route # 1 from the IAB node 300-R1 to the IAB node 300-D exists on the lower side of the lower node 300-C.
  • priority higher than priority "1”
  • the route with the lowest number of hops may be assigned the highest priority. It should be noted that such a priority can be set by the CU of the donor node by signaling the IAB-DU of each IAB node 300.
  • the lower node 300-C when the lower node 300-C receives, for example, the Type1 / 2 Instruction from the upper node 300-T, the route priority set for each route is changed, and then when the Type3 Instruction is received, the lower node 300-C changes the route priority. Return the route priority to the state before the change.
  • a failure occurrence notification indicating that a failure has occurred in the backhaul link or a recovery failure notification indicating that the first relay node has failed to recover from the failure in the backhaul link is sent.
  • the first request for changing the route priority is transmitted to the second relay node.
  • the priority of the first route from the second relay node to the fourth relay node via the third relay node in response to the reception of the first request by the second relay node. And / or change the priority of the second route from the second relay node to the fourth relay node via the fifth relay node.
  • the second relay node transmits a packet according to the priority of the changed first route and / or the priority of the changed second route.
  • FIG. 14 is a diagram showing an operation example in the fourth embodiment.
  • step S120 the cellular communication system 1 starts processing.
  • the upper node 300-T detects the RLF of the BH link # 1.
  • the upper node 300-T may detect a recovery failure of the BH link # 1 for the RLF.
  • the higher-level node 300-T may receive the Type1 / 2 Instruction transmitted from the higher-level IAB node 300.
  • the higher-level node 300-T may receive the Type 4 Instruction transmitted from the higher-level IAB node 300.
  • the upper node 300-T transmits a notification indicating a route priority change request to the lower node 300-C.
  • a notification indicating a route priority change request For example, in step S121, when the upper node 300-T detects the RLF of the BH link # 1, Type1 / 2 Instruction is transmitted to the lower node 300-C.
  • the Type1 / 2 Instruction itself may indicate a request to change the route priority.
  • the Type1 / 2 Instruction may include an indicator as to whether or not to change the route priority.
  • the Type 4 Instruction is transmitted to the lower node 300-C.
  • the Type 4 Instruction itself may indicate a request to change the route priority.
  • the Type 4 Instruction may include an indicator as to whether or not to change the route priority.
  • the upper node 300-T may transmit the Type1 / 2 Instruction or the Type4 Instruction received from the higher IAB node 300 to the lower node 300-C.
  • This Type1 / 2 Instruction or Type4 Instruction itself may indicate a request to change the route priority, or even if each Instruction includes an indicator as to whether or not to change the route priority. good.
  • the notification indicating the route priority change request may be transmitted using BAP Control PDU, SIB1, MAC CE, or the like.
  • step S123 the lower node 300-C changes the route priority.
  • the following are examples of changes to the route priority.
  • the lower node 300-C may regard the priority of the route with the highest priority (route # 1) as the lowest priority at present. In this case, in the example of FIG. 13, route # 1 has the lowest priority and route # 2 has the highest priority.
  • the lower node 300-C may regard the priority of the route of the second priority as the highest priority at present.
  • the route # 2 which is the second priority has the highest priority.
  • the lower node 300-C may lower the priority of the route having the highest priority by one or several at present. In this case, in the example of FIG. 13, if the lower node 300-C is to be lowered by two, the priority of the route # 1 is changed from "1" to "3". As a result, the priority of the changed route # 1 is lower than the priority "2" of the route # 2, and the route # 2 has the priority over the route # 1.
  • the lower node 300-C may currently raise the priority of routes other than the highest priority by one or several. In this case, in the example of FIG. 13, if the number is increased by two, the lower node 300-C changes the priority of the route # 2 from "2" to "0". As a result, route # 2 has the highest priority, which is higher than the priority of route # 1.
  • route priority may be temporary. Further, the lower node 300-C may change the priority of all the routes by combining not only the priority of some routes but also the above 1) to 4).
  • the lower node 300-C performs the routing process for the packet according to the changed route priority.
  • the IAB-MT of the lower node 300-C sends the packet addressed to the IAB node 300-D to the IAB node 300 on the route # 2 instead of the IAB node 300-R1 on the route # 1. -Send to R2.
  • step S125 when the upper node 300-T detects the restoration of the BH link # 1, it sends a notification indicating that the route priority is returned to the state before the change to the lower node 300-C.
  • the notification may be Type 3 Instruction itself. That is, the Type 3 Instruction itself may be a notification indicating that the route priority is returned to the original state before the change. Alternatively, the Type 3 Instruction may include an indicator indicating that the route priority is returned to the state before the change.
  • the recovery of the backhaul link is detected by the upper node 300-T receiving the Type 3 Instruction transmitted from the IAB node 300 higher than the upper node 300-T as well as the BH link # 1. May be.
  • the upper node 300-T will send a notification indicating that the route priority will be returned to the state before the change.
  • the lower node 300-C may perform a process of returning the route priority to the state before the change based on the normal recovery of its own BH link. For example, when the RRC Recovery to another parent node is successful, the process of returning the route priority to the state before the change is performed.
  • the lower node 300-C performs a process of returning the route priority to the original state before the change.
  • the IAB-DU (or IAB-MT) of the lower node 300-C may change the route priority set by step S123 to the priority set by the donor node.
  • the IAB-DU of the lower node 300-C may request the CU of the donor node to return the route priority to the state before the change.
  • the CU of the donor node may reset the route priority before the change by retransmitting the routing configuration transmitted before the route priority change to the IAB-DU of the lower node 300-C. ..
  • step S127 the lower node 300-C performs packet routing processing according to the route priority before the route priority is changed. For example, in the example of FIG. 13, the lower node 300-C sets the destination of the packet addressed to the IAB node 300-D from the IAB node 300-R2 on the route # 2 to the IAB node 300-R1 on the route # 1. Change to.
  • step S1208 the cellular communication system 1 ends a series of processes.
  • Type1 / 2 Instruction has been described in the fourth embodiment, Type1 Instruction or Type2 Instruction may be used instead of Type1 / 2 Instruction.
  • the second relay node receives a failure occurrence notification indicating that a failure has occurred in the backhaul link from the first relay node.
  • the second relay node deactivates the main path setting and activates the alternative path setting for the main path in response to the reception of the failure occurrence notification.
  • the path of route # 1 is the main path and the path of route # 2 is the alternative path.
  • the routing configuration includes, for example, the BAP address of each IAB node 300 on the main path and the BAP address of each IAB node 300 on the alternative path.
  • the former can be information about the setting of the main path, and the latter can be information about the setting of the alternative path.
  • FIG. 15 is a diagram showing an operation example of the fifth embodiment.
  • the IAB node 300-C starts processing in step S130.
  • step S131 when the IAB node 300-C receives the Type1 / 2 Instruction from the upper node 300-T, it deactivates the main path setting and activates the alternative path setting.
  • the IAB-DU of the IAB node 300-C stops reading the information regarding the setting of the main path stored in the memory, and starts reading the information regarding the setting of the alternative path stored in the memory.
  • the IAB node 300-C routes the packet to the activated path.
  • the IAB-DU of the IAB node 300-C transmits the packet received from the upper node 300-T to the IAB-MT of the IAB node 300-R2 based on the information regarding the setting of the alternative path.
  • step S133 when the IAB node 300-C receives the Type3 Instruction from the upper node 300-T, it activates the main path setting and deactivates the alternative path setting.
  • the IAB-DU of the IAB node 300-C starts reading the information about the setting of the main path stored in the memory and stops reading the information about the setting of the alternative path stored in the memory.
  • the IAB node 300-C routes the packet to the activated path.
  • the IAB-DU of the IAB node 300-C transmits the packet received from the upper node 300-T to the IAB-MT of the IAB node 300-R1 based on the information regarding the setting of the main path.
  • step S135 the IAB node 300-C ends a series of processes.
  • Type1 / 2 Instruction has been described in the fifth embodiment, Type1 Instruction or Type2 Instruction may be used instead of Type1 / 2 Instruction.
  • a program may be provided that causes the computer to execute each process performed by the UE 100 or the gNB 200.
  • the program may be recorded on a computer-readable medium.
  • Computer-readable media can be used to install programs on a computer.
  • the computer-readable medium on which the program is recorded may be a non-transient recording medium.
  • the non-transient recording medium is not particularly limited, but may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.
  • a circuit that executes each process performed by the UE 100 or the gNB 200 may be integrated, and at least a part of the UE 100 or the gNB 200 may be configured as a semiconductor integrated circuit (chipset, System on a chip).
  • Topology Adaptation Enhancements-Procedure specifications for interdonor IAB node movement to enhance robustness and load balancing, including enhancements to reduce signaling load. -Specifications of extended functions for reducing service interruptions due to IAB node movement and BH RLF recovery. -Extended specifications for topology redundancy, including support for CP / UP isolation. Topology, Routing, and Transport Enhancements-Extension specifications to improve overall topology fairness, multi-hop delay, and congestion mitigation.
  • BH backhaul
  • BH RLF BH RLF indication
  • existing functions such as RRC re-establishment, MCG / SCG failure indication, and / or conditional handover. Only the recovery procedure was specified.
  • Proposal 1 RAN2 should assume that the quality of the backhaul link will change dynamically. Therefore, backhaul RLF is not a rare case in Rel-17 eIAB.
  • Rel-16 BH RLF indication which allows the child IAB-MT to recognize the RLF on the BH link and initiate the RLF recovery procedure.
  • Proposal 2 RAN2 should agree that BH RLF indication type 2 "attempting recovery" has been introduced. Further consideration is needed as to whether it is transmitted via BAP Control PDU, SIB1, or both.
  • Proposal 3 If Proposal 2 can be agreed, RAN2 should consider whether explicit BH RLF indications, ie, type 3 "BH link recovery", should be introduced when BH RLF is gone. ..
  • IAB-MT reduce / stop SR when it receives a Type 2 indication and resume operation when it receives a Type 3 indication (ie, the parent IAB node loses BH RLF). .. This is one of the desirable IAB-MT behaviors when the parent node attempts to restore the BH link. It is assumed that other IAB-MT operations such as interrupting all RBs are also possible.
  • Proposal 4 RAN2 should agree to reduce / stop scheduling requests after IAB-MT receives a Type 2 indication and resume scheduling requests when the parent node runs out of BH RLF. be.
  • Local rerouting is expected to be used for congestion mitigation, load balancing, etc., but it may also be used for service continuity even in the case of upstream BH RLF such as a parent node.
  • an IAB node can execute local rerouting when it receives a type 2 indication, but with a routing setting such as Rel-16, an upstream BH RLF can be sent to the IAB node by receiving a type 3 indication.
  • the normal recovery notification is given, it returns to the normal routing.
  • Proposal 5 RAN2 should discuss any other IAB-MT behavior while the parent node is trying to recover the BH link, such as local rerouting.
  • the IAB-DU that sends the indication
  • the type 2 BH RLF indication will be sent.
  • RLF occurs on this BH link
  • an indication is transmitted, so it is easy for a single-connection BH.
  • the IAB node detects an RLF on the MCG, it initiates the MCG fault information procedure, but the SCG continues to function as a BH link, so there is no need to send a Type 2 indication at this point.
  • Type 2 indications are transmitted when RRC re-establishment is initiated, not when MCG / SCG failure information is triggered. In any case, this is intended for IAB-DU behavior, so careful consideration should be given to whether / how to capture to specifications. That is, in stages 2 and 3, it should be considered whether note needs to be added or nothing needs to be captured.
  • Proposal 6 RAN2 agrees that IAB-DU may send a Type 2 BH RLF indication when it initiates RRC reestablishment rather than when it initiates any of the RLF recovery procedures. Should be.
  • Proposal 7 RAN2 should discuss whether / how to capture the IAB-DU behavior (ie, Proposal 6) in the specification.
  • CHO extension function with indication (type 4) Conditional Handover (CHO) was introduced in Rel-16, and in our understanding, CHO can be used as-is for Rel-16 IAB. Many companies have proposed the extension of CHO or its use for the movement of interdonor IAB nodes.
  • CHO is executed when the corresponding CHO event (A3 / A5) is satisfied, or when the selected cell is a CHO candidate as a result of cell selection for RRC reestablishment.
  • These trigger conditions can be met when the IAB node experiences BH RLF on the BH link.
  • the radio state of the BH link owned by the IAB node is good, that is, under the RLF peculiar to IAB such as RLF by receiving the BH RLF indication (type 4), these cannot be satisfied.
  • one of the desirable actions is to execute CHO when the IAB node receives the BH RLF indication.
  • Proposal 8 RAN2 needs to consider whether additional trigger conditions for CHO are defined, that is, at least when the IAB node receives the BH RLF indication (type 4). If introduced, further consideration is needed to see if it can be applied to Type 2.
  • Finding 4 In Rel-16, when the IAB node attempts an RRC re-establishment request to a descendant node, the IAB node must wait for the failure and finally move to idle.
  • Proposal 9 RAN2 should agree that optimization of cell (re) selection is considered to avoid re-establishment to inappropriate nodes (eg, descendant nodes).
  • the common concept is considered to be that the IAB-MT is provided in either whitelist or blacklist for the purpose of cell selection.
  • Whitelists and blacklists have advantages depending on the topology and the location of the IAB node, given that topology changes can occur frequently on Rel-17, for example due to "moving interdonor IAB nodes". And there are disadvantages.
  • the blacklist may be more appropriate to reduce overhead, for example because it contains only the downstream IAB nodes of the IAB node of concern and, in some cases, only a small number of child IAB nodes.
  • Findings 5 Whitelists and blacklists have advantages and disadvantages depending on the topology and location of the IAB node.
  • the IAB donor or parent IAB node
  • Proposal 10 RAN2 should agree that the IAB-MT will be provided with a whitelist or blacklist (ie, a selection structure) for the purpose of cell selection to avoid re-establishment to descendant nodes. Further consideration is needed as to whether these lists can also be used for cell reselection procedures.
  • a whitelist or blacklist ie, a selection structure
  • Option 10 If Proposal 10 can be agreed, further consideration should be given to how the information (ie, whitelist or blacklist) is provided.
  • Option 1 assumes a CHO setting and may require some extensions.
  • Option 2 envisions additional indications, such as type 2 BH RLF indications.
  • Option 3 is intended to provide information about the entire topology that is not in the existing configuration.
  • Option 5 is supposed to be set by OAM, but as the reporter pointed out, this is suspicious.
  • Proposal 11 RAN2 should agree that the whitelist / blacklist is dynamically provided by the parent IAB node or IAB donor each time the topology changes. Further studies are needed for details.
  • the second solution "Reroute buffered PDCP PDUs at intermediate IAB nodes," was supported as an implementation choice at the BAP layer. Further, the BAP layer may be executed "for example, data buffering in the transmission part of the BAP entity is implementation-dependent until the RLC-AM entity receives the acknowledgment". These BAP implementations were considered to avoid packet loss in the "most" cases of the Rel-16 deployment scenario, i.e. when using fixed IAB nodes, but are not perfect, for example, as in Figure 19. rice field.
  • the third solution “Introduction of UL status distribution,” was a promising solution for guaranteeing lossless distribution of UL data in consideration of the evaluation results cited in FIG.
  • the idea was to delay the RLC ARQ to the UE so that it would start when PDCP data recovery in the UE was needed.
  • a fixed IAB node was assumed, it was considered rare that UL packets were dropped due to a topology change, so it was not specified in Rel-16.
  • RAN2 should discuss, in addition to the results captured by TR, an extended mechanism to ensure lossless delivery within the L2 multihop network.
  • Proposal 12 is a solution identified in TR38.874, a mechanism that guarantees lossless delivery under conditions where topological changes may occur frequently based on some form of "UL status delivery". Should be agreed to be introduced.
  • C-2 should be an extended baseline for Rel-17 for lossless delivery of UL packets.
  • C-2 which is the solution to "introduction of UL status distribution" may be an extended baseline for Rel-17, which can also be implemented for Rel-16.
  • Rel-17 should assume a dynamic topology change that causes UL packet loss
  • the extension of Rel-17 will support C-2 as a standard support function.
  • At least the stage 2 specification should explain the overall mechanism based on C-2. Otherwise, the 3GPP standard does not guarantee lossless delivery during the handover of the IAB node.
  • small changes such as RLC and / or BAP are expected in stage 3, but details may not be specified as they are considered internal behavior of the IAB node.
  • Proposal 13 RAN2 should agree to specify an RLC ARQ mechanism for lossless delivery of UL packets in stage 2. This delays the transmission of the ACK to the child node / UE before receiving the ACK from the parent IAB node (ie, C-2). Whether or not to specify in stage 3 / how to specify it needs further consideration.
  • the IAB node integration procedure has been introduced in Rel-16, which is used for the initial integration of IAB nodes. In other words, it is still in the service outage stage.
  • Rel-17 aims to specify the movement of the Interdonor IAB node, which will provide robust operation and will be applied to mobile IAB nodes. Unlike Rel-16, the movement of the Interdonor IAB node of Rel-17 is performed during the active phase, so the movement of the Interdonor IAB node of one IAB node affects the entire topology and of the service. Cause interruption.
  • moving an interdonor IAB node in Rel-17 is a method of moving all IAB nodes in the IAB topology to another IAB donor, specifically an RRC reconfiguration with synchronization (ie, a handover command). Need to be considered how is provided to these affected IAB nodes.
  • -Case 1 When the parent is moved first, the RRC signaling path between the child and the source donor is released. Therefore, it is unclear how the child node can be moved.
  • -Case 2 When the child is first moved, the RRC signaling path to the target donor via the parent node has not yet been established. Therefore, it is unclear how the child node will access the target donor (ie, how to complete the RRC reconfiguration and send it to the target donor).
  • Rel-17 may not be expected as a solution.
  • the overall procedure for moving interdonor IAB nodes is being considered in RAN3, but RAN2 needs to consider the impact of RAN2 on how to reconfigure multiple IAB nodes in a multi-hop network.
  • Proposal 14 RAN2 needs to consider how to reconfigure the multi-hop IAB node for interdonor IAB node movement.

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  • Mobile Radio Communication Systems (AREA)
  • Radio Relay Systems (AREA)
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US20230328629A1 (en) 2023-10-12
EP4224902A4 (en) 2024-05-29
EP4224902B1 (en) 2025-07-02
EP4224902A1 (en) 2023-08-09
CN116671149B (zh) 2026-01-27
CN116671149A (zh) 2023-08-29
JP2024079777A (ja) 2024-06-11
JP7618689B2 (ja) 2025-01-21
JPWO2022085696A1 (https=) 2022-04-28

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