Communication control method, relay node, cellular communication system, chipset and program

Abstract

Distribute the load appropriately and minimize service interruptions. [Solution] One aspect of the present invention relates to a communication control method for use in a cellular communication system. The communication control method includes a step in which a donor node sets, to a relay node, binding information between a first routing ID included in a packet and a second routing ID indicating an output destination. The communication control method also includes a step in which the relay node transmits the packet to at least one of a first relay node on a first path indicated by the first routing ID and a second relay node on a second path indicated by the second routing ID, in accordance with the binding information.

Description

[Technical Field]

[0001] The present disclosure relates to a communication control method, a relay node, a cellular communication system, a chipset, and a program. [Background technology]

[0002] In the 3GPP (Third Generation Partnership Project), a standardization project for cellular communication systems, the introduction of a new relay node called an IAB (Integrated Access and Backhaul) node is being considered (see, for example, Non-Patent Document 1). 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 V16.8.0(2021-12) 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 in which a donor node sets, to a relay node, binding information between a first routing ID included in a packet and a second routing ID indicating an output destination. The communication control method also includes a step in which the relay node transmits the packet to at least one of a first relay node on a first path indicated by the first routing ID and a second relay node on a second path indicated by the second routing ID in accordance with the binding information. [Brief explanation of the drawings]

[0005] [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] FIG. 9 is a diagram illustrating an example of the configuration of "PDCP-based DAPS-like" according to the first embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of the configuration of "BAP-based DAPS-like" according to the first embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of operation according to the first embodiment. [Figure 12] FIG. 12 is a diagram illustrating an example of operation according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0006] The present disclosure aims to appropriately perform load balancing and to suppress interruptions to services.

[0007] 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.

[0008] (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.

[0009] FIG. 1 is a diagram showing an example of the configuration of a cellular communication system 1 according to an embodiment.

[0010] 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.

[0011] 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).

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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).

[0018] 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.

[0019] 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, 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 is wirelessly connected 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.

[0020] FIG. 2 is a diagram showing an example of the relationship between an IAB node 300, parent nodes, and child nodes.

[0021] 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.

[0022] 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.

[0023] Adjacent nodes (i.e., lower nodes) on the NR access interface of the IAB-DU are called child nodes. The IAB-DU manages a cell, similar to the gNB 200. 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 the donor node 200-1. While FIG. 2 shows an example in which the child nodes of the IAB node 300 are IAB nodes 300-C1 to 300-C3, the child nodes of the IAB node 300 may also include the UE 100. The direction toward the child nodes is called downstream.

[0024] Furthermore, all IAB nodes 300 connected to the donor node 200 via one or more hops form a directed acyclic graph (DAG) topology (hereinafter, sometimes referred to as "topology") with the donor node 200 as the root. In this topology, as shown in FIG. 2, adjacent nodes on the IAB-DU interface are child nodes, and adjacent nodes on the IAB-MT interface are parent nodes. The donor node 200 centrally manages, for example, resources, topology, and route management of the IAB topology. The donor node 200 is a gNB that provides network access to the UE 100 via a network of backhaul links and access links.

[0025] (Base station configuration) Next, a 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, encoding / decoding, etc. 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. Note that the control unit 230 may perform each process or operation in the gNB 200 in each of the embodiments described below.

[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. Note that the control unit 320 may perform each process or operation in the IAB node 300 in each of the embodiments described below.

[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. Note that the control unit 120 may perform each processing in the UE 100 in each of the embodiments described 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 IAB node 300-2 has a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) 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. (About "DAPS-like") 3GPP introduced DAPS HO (Dual Active Protocol Stack Handover) in Release-16. DAPS HO is a handover procedure that maintains connection with the source gNB after successful random access to the target gNB until the connection with the source cell is released. The UE maintains connection with the source gNB until random access with the target gNB is successful. Therefore, DAPS HO can, for example, prevent service interruptions caused by HO for the UE.

[0051] In 3GPP, there is a discussion about applying the DAPS HO solution to IAB. Such a solution is sometimes called a "DAPS-like solution" (or "DAPS-like").

[0052] For example, "DAPS-like" may be applied to a scenario in which the IAB node 300 migrates to a parent node 300-P or a conditional handover (CHO). Such a scenario can be said to be a scenario in which the IAB node 300 switches connections using "DAPS-like."

[0053] On the other hand, there is also discussion about using "DAPS-like" for load balancing within a topology. For example, in the case where multiple paths are set in advance in the IAB node 300 and a given packet is forwarded to multiple paths, it becomes possible to distribute the load caused by packet forwarding that is concentrated on a specific path. Furthermore, load balancing can also suppress service interruptions for the UE 100.

[0054] In general, the CU of the donor node 200 sets a routing configuration for the IAB-DU of each IAB node 300 in the same topology. The BAP entity (or BAP layer; hereinafter, the terms "entity" and "layer" may be used interchangeably) in the IAB-DU of each IAB node 300 transmits a BAP packet received from the previous hop or a higher layer to the next hop according to the routing configuration.

[0055] Here, a scenario may be considered in which the above-mentioned load balancing is realized by updating (or changing) the routing settings.

[0056] However, various problems can arise when updating routing settings. For example, if it takes a long time to update the routing settings, many packets that were forwarded using the routing settings before the update will be included in the topology. If the updated routing settings are applied to such packets, erroneous transmission may occur.

[0057] Therefore, it is desirable to perform load balancing without updating the routing settings.

[0058] There are roughly two types of "DAPS-like":

[0059] Option A) PDCP-based DAPS-like Option B) BAP-based DAPS-like

[0060] Fig. 9 is a diagram illustrating a configuration example of "PDCP-based DAPS-like" (hereinafter, sometimes referred to as "Option A") according to the first embodiment. In Fig. 9, IAB node 300-A is also an access IAB node. The access IAB node is a node that first processes a packet received from UE 100 and a node that last processes a packet to be transmitted to UE 100.

[0061] In option A, two paths are established on the PDCP link between the PDCP entity of the UE 100 and the PDCP entity of the donor node 200. For example, the UE 100 configures a group of entities (first entities) from a PHY entity to an RLC entity, and another group of entities (second entities) from a PHY entity to an RLC entity. The UE 100 has two groups of entities. The RLC entity of the first group of entities transmits an RLC packet to the IAB node 300-A, and the RLC entity of the second group of entities transmits the RLC packet to the IAB node 300-A. This enables packet forwarding via two paths between the UE 100 and the IAB node 300-A (access IAB node) in the upstream direction, as shown in FIG. 9 .

[0062] Note that setting up two groups of entities in this way is sometimes referred to as the "existing DAPS HO function."

[0063] On the other hand, FIG. 10 is a diagram showing an example of the configuration of "BAP-based DAPS-like" (hereinafter, sometimes referred to as "Option B") according to the first embodiment.

[0064] Option B is an example in which the existing DAPS HO function is ported to the BAP entity of IAB node 300-A, and two paths are established between the BAP layer of IAB node 300-A and the BAP layer of donor node 200. Option B differs from Option A in that two entity groups are not configured in UE 100. Therefore, in Option B, only one path is established between UE 100 and IAB node 300-A (access IAB node).

[0065] Comparing the two options, option A requires the same packet to be transmitted twice between the UE 100 and the access IAB node 300-A, whereas option B requires only one transmission. Therefore, option A has a problem in that the packet transmission efficiency is lower than option B. Note that the above-mentioned examples of option A and option B are examples for the upstream direction, but in the case of the downstream direction, both option A and option B result in the donor node 200 transmitting the same packet twice.

[0066] Furthermore, option A has a problem in that it cannot execute option A itself unless UE 100 supports DAPS HO. Furthermore, DAPS HO is a function for handover in the first place, and does not assume the above-mentioned load balancing.

[0067] Therefore, in the first embodiment, option B will be described.

[0068] In the following, "DAPS-like" will be referred to as "Route Aggregation." In addition, the following will explain the case where "DAPS-like" is used for load balancing, and such a case may also be explained as being included in the term "Route Aggregation."

[0069] In route aggregation, different packets may be transmitted via multiple paths. That is, route aggregation has the characteristics of carrier aggregation. In addition, in route aggregation, different packets may be transmitted via multiple next hop nodes. That is, route aggregation has the characteristics of dual connectivity. Furthermore, in route aggregation, the same packet may be duplicated and transmitted via multiple routes, multiple parent nodes, or multiple child nodes. That is, route aggregation has the characteristics of packet duplication. In this way, route aggregation has characteristics similar to existing technologies.

[0070] Route aggregation also shares similar characteristics with existing IAB technology. That is, route aggregation may send different packets via multiple routes or multiple next-hop nodes. This is also a characteristic of routing. Route aggregation may also send the same packet via multiple routes or multiple next-hop nodes without duplicating it. This is also a characteristic of local rerouting.

[0071] In this way, it can be said that route aggregation has the characteristics of existing technologies.

[0072] (Communication control method according to the first embodiment) Next, a communication control method relating to route aggregation will be described. In the first embodiment, an example will be described in which routing IDs are bundled, linked, and route aggregation is performed using the linked routing IDs.

[0073] Specifically, first, a donor node (e.g., donor node 200) sets, for a relay node (e.g., IAB node 300-A), information linking a first routing ID included in a packet with a second routing ID indicating an output destination. Second, the relay node transmits the packet to at least one of a first relay node (e.g., IAB node 300-P1) on a first path indicated by the first routing ID and a second relay node (e.g., IAB node 300-P2) on a second path indicated by the second routing ID, in accordance with the linking information.

[0074] As a result, packets are transmitted in at least one direction of the first path indicated by the first routing ID and the second path indicated by the second routing ID, so that packet forwarding is not concentrated on one path, and load balancing can be appropriately achieved. Also, since the IAB node 300 transmits packets according to the binding information, load balancing can be achieved even for UEs 100 that do not support DAPS HO. Furthermore, since the donor node 200 sets the binding information for the IAB node 300, load balancing can be achieved without updating the routing setting. And, by appropriately achieving such load balancing, it is possible to suppress service interruptions for the UEs 100.

[0075] In the following, the BAP routing ID may be referred to as a routing ID. The routing ID is composed of a BAP address and a BAP path ID. The BAP address indicates the destination node of the packet. The BAP path ID indicates the routing path that the packet follows to reach the destination node. In the following, the BAP path ID may be referred to as a path ID.

[0076] (Operation example according to the first embodiment) FIG. 11 is a diagram illustrating an example of operation according to the first embodiment.

[0077] The operation example shown in Fig. 11 includes not only the upstream direction but also the downstream direction. Furthermore, the operation example shown in Fig. 11 also includes the upstream direction operation example not only of the access IAB node 300-A but also of an IAB node 300-T other than the access IAB node 300-A.

[0078] Therefore, in the following operation example, the IAB node 300-T will be used as an example of an IAB node. The IAB node 300-T also includes the access IAB node 300-A, IAB node 300-P1, and IAB node 300-P2 shown in FIGS. 9 and 10.

[0079] As shown in FIG. 11, in step S10, the IAB node 300-T starts processing.

[0080] In step S11, the IAB node 300-T may notify the donor node 200 that it supports route aggregation. For example, the IAB-DU of the IAB node 300-T may notify the CU of the donor node 200 by transmitting an F1AP message including the notification. Alternatively, for example, the IAB-MT of the IAB node 300-T may notify the CU of the donor node 200 by transmitting an RRC message including the notification.

[0081] In step S12, the donor node 200 sets a route aggregation configuration for the IAB node 300-T. Specifically, the donor node 200 sets binding information that links a routing ID (first routing ID) included in a packet received by the IAB node 300-T with a routing ID (second routing ID) that indicates its output destination. Alternatively, the donor node 200 may set a binding table having multiple pieces of binding information for the IAB node 300-T.

[0082] Here, there are two patterns for linking two routing IDs.

[0083] The first pattern is a pattern that links routing ID #1 (first routing ID) with routing ID #2 (second routing ID). In this case, a BAP packet having routing ID #1 in its BAP header becomes a packet that is subject to route aggregation. Then, the packet is output to at least one of the next hop node on the path indicated by routing ID #1 (e.g., IAB node 300-P1) and the next hop node on the path indicated by routing ID #2 (e.g., IAB node 300-P2).

[0084] The second pattern is a pattern in which routing ID#A (first routing ID) is linked to routing ID#1 (second routing ID), and routing ID#A is linked to routing ID#2 (third routing ID). In this case, a BAP packet having routing ID#A in its BAP header becomes a packet subject to route aggregation. Then, the packet is output to at least one of the next hop node on the path indicated by routing ID#1 (e.g., IAB node 300-P1) and the next hop node on the path indicated by routing ID#2 (e.g., IAB node 300-P2).

[0085] In addition to the two patterns mentioned above, a third pattern is also possible. The third pattern is a pattern in which a secondary next-hop BAP address is associated with the existing information linking a routing ID and a next-hop BAP address. In other words, two next-hop BAP addresses are associated with one routing ID. In this case, a packet having the routing ID in its BAP header becomes a packet subject to route aggregation. Then, the packet is output to at least one next-hop node of the next-hop BAP address and / or the secondary next-hop BAP address.

[0086] The information included in the root aggregation configuration may further include the following:

[0087] First, the routing ID on the output side may consist of three or more routing IDs.

[0088] Second, priority information may be set for each routing ID on the output side. For example, in the second pattern described above, priority information may be assigned such that routing ID #1 is the primary route and routing ID #2 is the secondary route. Also, in the first pattern described above, for example, a rule may be set such that the routing ID to be aggregated is the primary route and the others are secondary routes. This rule may also be information included in the route aggregation setting.

[0089] Third, information indicating whether to selectively transmit packets to be aggregated or to duplicate them (packet duplication) may be included. In the case of selective transmission, a selection criterion or threshold may further be included. Selective transmission means selecting (for each packet) whether to output a packet to the primary route or the secondary route. Duplicate transmission means outputting the same packet to both the primary route and the secondary route. Specific examples will be described later.

[0090] The route aggregation configuration may be included in, for example, an F1AP message and transmitted from the CU of the donor node 200 to the IAB-DU of the IAB node 300-T. Also, the route aggregation configuration may be included in, for example, an RRC message and transmitted from the CU of the donor node 200 to the IAB-MT of the IAB node 300-T.

[0091] In step S13, the BAP layer of the IAB node 300-T receives a packet from a previous hop node or an upper layer. The previous hop node may be the parent node 300-P of the IAB node 300-T. In this case, the IAB node 300-T transmits the received packet in the downstream direction. The previous hop node may be the child node 300-C of the IAB node 300-T. In this case, the IAB node 300-T transmits the received packet in the upstream direction. When the IAB node 300-T receives a packet from an upper layer, the IAB node 300-T is the access IAB node 300-A, and receives a packet directly from the UE 100 and transmits it in the upstream direction. When the IAB node 300-T receives a packet from an upper layer, the IAB node 300-T is the donor node 200, and receives a packet directly from the CU of the donor node 200 and transmits it in the downstream direction.

[0092] In step S14, the BAP layer of the IAB node 300-T determines whether the packet is a target for route aggregation based on the linking information. Specifically, the BAP layer determines that the packet is a target for route aggregation if the routing ID included in the BAP header of the packet is included in the linking information, and determines that the packet is not a target for route aggregation if the routing ID included in the BAP header of the packet is not included in the linking information.

[0093] In step S14, if the packet is subject to route aggregation (YES in step S14), the process proceeds to step S15. On the other hand, if the packet is not subject to route aggregation (NO in step S14), the process proceeds to step S16.

[0094] In step S15, the BAP layer of the IAB node 300-T performs route aggregation processing. The route aggregation processing includes packet distribution processing and header rewriting processing. First, the packet distribution processing will be described.

[0095] (Packet sorting process) In the route aggregation process, the BAP layer of the IAB node 300 performs packet distribution processing and selects at least one of the primary route and the secondary route as the destination of the packet.

[0096] There are two types of packet distribution processing: selective transmission and duplicate transmission. The BAP layer of the IAB node 300 selects whether to perform selective transmission or duplicate transmission. First, selective transmission will be explained.

[0097] Selective transmission is when the BAP layer of the IAB node 300-T selects whether to transmit the packet via the primary route or the secondary route. Specifically, the BAP layer selects either the IAB node 300 (e.g., the first relay node) on the path indicated by the routing ID of the primary route or the IAB node 300 (e.g., the second relay node) on the path indicated by the routing ID of the secondary route.

[0098] The routing ID of the primary route and the routing ID of the secondary route also correspond to two routing IDs linked by the linking information included in the route aggregation configuration. In other words, the BAP layer selects the primary route and the secondary route from the two routing IDs linked by the linking information. Which of the two routing IDs is the primary route and which is the secondary route may be included in the route aggregation configuration as priority information, as described above.

[0099] The BAP layer may determine the output route (whether to output to the primary route or the secondary route) according to the following selection criteria:

[0100] First, the BAP layer may determine the output route based on the data buffer capacity of its own node. Specifically, the BAP layer may select the primary route when the data buffer capacity of its own node is below a threshold (i.e., no congestion occurs). On the other hand, the BAP layer may select the primary route or the secondary route (for each packet), or may select only the secondary route when the data buffer capacity of its own node is above a threshold (i.e., congestion occurs).

[0101] Second, the BAP layer may determine the output route based on the buffer capacity of the next hop node. Specifically, if the available buffer size included in the flow control feedback notified from the parent node 300-P of the IAB node 300-T or the child node 300-C of the IAB node 300-T is equal to or greater than a threshold (i.e., no congestion occurs), the BAP layer may select the primary route. On the other hand, if the available buffer size is equal to or less than a threshold (i.e., congestion occurs), the BAP layer may select the primary route or the secondary route (for each packet), or may select only the secondary route.

[0102] Third, the BAP layer may determine the output route based on the throughput. Specifically, the BAP layer may select the primary route when the output throughput is above a threshold (i.e., no congestion occurs). On the other hand, the BAP layer may select either the primary route or the secondary route (for each packet), or only the secondary route, when the output throughput is below a threshold (i.e., congestion occurs).

[0103] Fourth, the BAP layer may determine the output route based on a fixed ratio. Specifically, the BAP layer selects a primary route or a secondary route (for each packet) according to a fixed ratio. For example, if a fixed ratio of 70:30 is set for the primary route and the secondary route, the BAP layer selects 70% of packets to be output via the primary route and 30% of packets to be output via the secondary route. The fixed ratio may be part of the information included in the route aggregation configuration described above.

[0104] Next, duplicate transmission included in the distribution process will be explained. Specifically, duplicate transmission is a process in which the BAP layer selects both the first IAB node (e.g., the first relay node) on the first path indicated by the first routing ID and the second IAB node (e.g., the second relay node) on the second path indicated by the second routing ID. For this reason, the BAP layer performs a process of duplicating the packet. That is, the BAP layer duplicates a predetermined number of packets (=(number of destination routes)-1). The BAP layer also selects an output route. There may be two or more destination routes. For the packet to be subjected to route aggregation, the BAP layer selects all of the output side routing IDs included in the binding information (e.g., routing ID #1 and routing ID #2) as output routes.

[0105] (Header rewriting process) Next, we will explain the header rewriting process included in the route aggregation process. The header rewriting process is a process of rewriting the routing ID (e.g., the first routing ID) included in the packet to the routing ID (e.g., the second routing ID or the third routing ID) of the route selected in the distribution process.

[0106] For example, if the packet contains routing ID #1 (e.g., the first routing ID) and the BAP layer selects a route with routing ID #2 (e.g., the second routing ID) in the sorting process, it rewrites the routing ID of the packet from routing ID #1 to routing ID #2. Also, if the packet contains routing ID #A (e.g., the first routing ID) and the BAP layer selects a route with routing ID #2 (e.g., the third routing ID) in the sorting process, it rewrites the routing ID of the packet from routing ID #A to routing ID #2.

[0107] First, if the routing ID included in the packet is the same as the routing ID of the selected route, the BAP layer may skip the header rewriting process. For example, if the packet includes routing ID #1 and the route of routing ID #1 is selected in the distribution process, the BAP layer may skip the header rewriting process.

[0108] Second, in the case of duplicate transmission, the BAP layer rewrites the routing ID of the selected route for each packet sent to each route. For example, if the packet contains routing ID #1 and duplicate transmission is performed to the route of routing ID #1 and the route of routing ID #2, the BAP layer performs the following: That is, the BAP layer rewrites the header of the packet sent to the route to routing ID #1 to routing ID #1, and rewrites the header of the packet sent to the route to routing ID #2 to routing ID #2. Furthermore, if there is a packet to be sent to the route to routing ID #3 due to duplicate transmission, the BAP layer rewrites the header to routing ID #3.

[0109] With the above, the BAP layer completes the route aggregation process.

[0110] In step S16, the BAP layer of the IAB node 300-T performs routing processing and BH RLC channel mapping processing, and transmits the packet to the next-hop node. Specifically, the BAP layer identifies a next-hop BAP address corresponding to the routing ID through the routing processing, and identifies an egress link. Then, the BAP layer identifies a BH RLC channel corresponding to the egress link through BH RLC channel mapping processing. Thereafter, the BAP layer transmits the packet to the BH RLC channel. As a result, the packet is transmitted to the next-hop node (e.g., at least one of the first relay node and the second relay node).

[0111] Then, in step S17, the series of processes ends.

[0112] In the above-described embodiment, a method for linking a first routing ID and a second routing ID has been described. The destination BAP addresses included in the routing IDs may be the same in route aggregation. Therefore, instead of linking by routing ID, linking by path ID may be performed. That is, the donor node 200 sets up a link between the first path ID and the second path ID for the IAB node 300-T. In this case, the linking information is information linking the first path ID and the second path ID.

[0113] [Second embodiment] Next, a second embodiment will be described. In the first embodiment, an example has been described in which the BAP layer performs route aggregation processing in accordance with the route aggregation setting. In the second embodiment, an example is shown in which the donor node 200 dynamically changes the route aggregation setting for the IAB node 300-T.

[0114] Specifically, a donor node (e.g., donor node 200) instructs a relay node (e.g., IAB node 300-T) to perform route aggregation processing. Here, the instruction is at least one of designating an output route, designating the start and / or stop of selective transmission, and designating the start and / or stop of overlapping transmission. Specific instruction contents will be explained in an operation example.

[0115] The donor node 200 can dynamically change the root aggregation configuration according to this instruction.

[0116] (Example of operation according to the second embodiment) FIG. 12 is a diagram illustrating an example of operation according to the second embodiment.

[0117] As shown in FIG. 12, in step S20, the donor node 200 starts the process.

[0118] In step S21, the donor node 200 performs a root aggregation configuration for the IAB node 300-T. The root aggregation configuration is the same as that in the first embodiment. The donor node 200 may specify an initial state of the root aggregation process in the root aggregation configuration. For example, the donor node 200 may include information indicating that the root aggregation configuration is performed as the initial state but the root aggregation process is not performed (=the same operation as when the root aggregation is not configured) in the root aggregation configuration. In the following operation example, a description will be given assuming that the initial state is specified to perform the root aggregation configuration but not the root aggregation process.

[0119] In step S22, the IAB node 300-T performs normal routing processing and BH RLC channel processing on each received packet, and transmits each packet to the next hop node.

[0120] In step S23, the donor node 200 instructs the IAB node 300-T to perform a route aggregation process.

[0121] The instruction may be included in an RRC message or a BAP Control PDU. For example, the CU of the donor node 200 may transmit an RRC message including the instruction to the IAB-MT of the IAB node 300-T. Also, for example, the DU of the donor node 200 may transmit a BAP Control PDU including the instruction to the IAB-MT of the IAB node 300-T. The instruction may be in the form of a command. The instruction may be included in an F1AP message. The content of the instruction may be at least one of the following:

[0122] That is, first, the content of the instruction may be to start and stop the route aggregation process. Specifically, as follows: That is, the content of the instruction may be to start and stop the selective transmission described in the first embodiment. Also, the content of the instruction may be to start and stop the duplicate transmission described in the first embodiment. Alternatively, the content of the instruction may be expressed as a choice syntax that selects either selective transmission, duplicate transmission, or no processing.

[0123] Second, the content of the instruction may be a specification of a destination route. Specifically, the content of the instruction may be as follows. That is, the content of the instruction may specify whether the destination route is a primary route or a secondary route (or whether both are destination routes). Also, the content of the instruction may specify a routing ID indicating the destination route. Furthermore, the content of the instruction may specify a next hop address indicating the destination route. Furthermore, the content of the instruction may specify a destination route for the routing ID to be aggregated. That is, the content of the instruction may be an instruction for route aggregation processing for each routing ID.

[0124] The donor node 200 may send the instruction when triggered by the following:

[0125] That is, first, there is a case where load balancing is used as a trigger. Specifically, it is as follows. That is, the donor node 200 may send the instruction when it detects that congestion is occurring on a certain route as a trigger. Also, the donor node 200 may send the instruction when it detects that the load is unbalanced on a certain route as a trigger. In this case, the donor node 200 may determine that the load is unbalanced when the difference in load between a certain route and another route is equal to or greater than a certain value.

[0126] Second, the donor node 200 may send the instruction when it detects that a packet loss occurs on a certain route, that the throughput of a certain route has dropped below a certain value, or that the delay of a certain route has exceeded a certain value.

[0127] Third, the donor node 200 may transmit the instruction when a state opposite to the state described in the trigger condition for load balancing occurs, as a trigger. Alternatively, the donor node 200 may transmit the instruction when a state opposite to the state described in the trigger condition for communication characteristics occurs, as a trigger. For example, the donor node 200 may transmit the instruction when it detects that congestion on a certain route has been resolved. In this case, for example, the donor node 200 may transmit the instruction including an instruction to start route aggregation processing when it detects that congestion has occurred, and may transmit the instruction including an instruction to stop route aggregation processing when it detects that the congestion has been resolved.

[0128] In step S24, the IAB node 300-T receives the instruction and determines whether to start or stop the route aggregation process according to the content of the instruction, and also determines how to perform the route aggregation process according to the content of the instruction. For example, if the instruction includes starting selective transmission and a primary route, the IAB node 300-T determines to start the route aggregation process and to perform selective transmission to the primary route as the route aggregation process. Then, the IAB node 300-T performs the route aggregation process according to the determination. The subsequent processing is the same as in the first embodiment.

[0129] Then, in step S25, the series of processes ends.

[0130] [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.

[0131] In addition, circuits that execute each process performed by UE100 or gNB200 may be integrated, and at least a portion of UE100 or gNB200 may be configured as a semiconductor integrated circuit (chip set, SoC: System on a chip).

[0132] 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 within the scope of the gist. The above-described embodiments, operation examples, processes, or steps can also be combined within the scope of not causing any contradiction.

[0133] 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.

[0134] This application claims priority from Japanese Patent Application No. 2022-001821 (filed January 7, 2022), the entire contents of which are incorporated herein by reference.

[0135] (Addendum) The features of the above-described embodiment will now be described.

[0136] (1) A communication control method for use in a cellular communication system, comprising: A step in which the donor node sets, in the relay node, information linking the first routing ID included in the packet with the second routing ID indicating the output destination; the relay node transmitting the packet to at least one of a first relay node on a first path indicated by the first routing ID and a second relay node on a second path indicated by the second routing ID in accordance with the linking information, Communication control method.

[0137] (2) The step of transmitting the packet includes: the relay node determining whether the packet is a target for route aggregation based on the binding information; and transmitting the packet, which is determined to be a target of the route aggregation, by the relay node in accordance with the linking information. The communication control method according to (1) above.

[0138] (3) the step of transmitting the packet includes a step of the relay node performing a distribution process; The step of performing the allocation process includes: a step of the relay node selecting and transmitting either the first relay node or the second relay node; and the relay node performs duplicate transmission by selecting both the first relay node and the second relay node, The communication control method according to (1) above.

[0139] (4) the step of transmitting the packet includes a step of the relay node performing a header rewriting process; the step of performing the header rewriting process includes a step of the relay node rewriting the first routing ID to one of the second routing ID and the third routing ID; The communication control method according to (1) above.

[0140] (5) the step of performing the header rewriting process includes a step of the relay node not rewriting the routing ID to the first routing ID when the routing ID included in the header of the packet is the first routing ID; The communication control method according to (4) above.

[0141] (6) The method further includes a step in which the donor node instructs the relay node to perform a route aggregation process, The instruction is at least one of a designation of an output destination route, a designation of starting and / or stopping the selective transmission, and a designation of starting and / or stopping the overlapping transmission. The communication control method according to (3) above. [Explanation of symbols]

[0142] 1: Mobile communication system 10:5GC 100:UE 110: Wireless communication unit 130: Control unit 200: Donor Node (gNB) 210: Radio Communication Department 230: Control unit 300 (300-T, 300-A, 300-P1, 300-P2): IAB node 310: Radio Communication Department 320: Control unit

Claims

1. A communication control method used in a cellular communication system, The relay node receives configuration information from the donor node, including information linking the first routing ID contained in the packet with the second routing ID representing the destination, and a threshold for the buffer size. The relay node receives flow control feedback, including the available buffer size, from its first child node. The relay node selects a route that is not congested based on the available buffer size and the threshold for the buffer size, The relay node transmits packets received from the parent node to the second child node via the route. Communication control method.

2. A relay node used in a cellular communication system, A receiving unit receives configuration information from a donor node, including information linking a first routing ID contained in a packet with a second routing ID representing the output destination and a threshold for the buffer size, and receives flow control feedback including the available buffer size from the first child node of the relay node. A control unit that selects a route that is not congested based on the available buffer size and a threshold related to the buffer size, It includes a transmitting unit that transmits packets received from the parent node to a second child node via the aforementioned route. Relay node.

3. A cellular communication system having relay nodes and donor nodes, The relay node receives configuration information from the donor node, including information linking a first routing ID contained in a packet with a second routing ID representing the destination, and a threshold for the buffer size. The relay node receives flow control feedback, including the available buffer size, from its first child node. The relay node selects a route that is not congested based on the available buffer size and the threshold for the buffer size. The relay node transmits the packet received from the parent node to the second child node via the route. Cellular communication system.

4. It is a chipset for a relay node, The donor node receives configuration information including the association between the first routing ID contained in the packet and the second routing ID representing the output destination, as well as a threshold for the buffer size. The relay node receives flow control feedback, including the available buffer size, from the first child node. Based on the available buffer size and the threshold for the buffer size, select a route that is not congested, This includes sending a packet received from the parent node to the second child node via the aforementioned route. Chipset.

5. For relay nodes used in cellular communication systems, The process involves receiving configuration information from the donor node, including the association information between the first routing ID contained in the packet and the second routing ID representing the output destination, as well as a threshold for the buffer size. The process of receiving flow control feedback, including the available buffer size, from the first child node of the relay node, A process to select a route that is not congested based on the available buffer size and the threshold for the buffer size, The process involves sending a packet received from the parent node to the second child node via the aforementioned route. program.

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