Communication device, control method, and program

Abstract

Disclosed is a communication device characterized by including: a determination means for determining whether a host node functioning as an integrated access and backhaul (IAB) node forming one IAB network is capable of operating as a boundary IAB node, which is an IAB node connected to both the one IAB network and another IAB network; and a transmission means for transmitting a communication message corresponding to a determination result from the determination means on the basis of the determination result.

Description

Communication device, control method, and program

[0001] The present disclosure relates to a communication device, a control method, and a program.

[0002] In the 3rd Generation Partnership Project (3GPP) (registered trademark), standardization of IAB (Integrated Access and Backhaul) is underway as a communication technology for backhaul.

[0003] The IAB technology is a technology that simultaneously uses millimeter-wave wireless communication in the 28 GHz band or the like, which is used for access communication between a base station and user equipment (UE), as backhaul communication (Patent Document 1).

[0004] In backhaul communications using IAB technology, relay devices called IAB nodes relay communications from IAB donors, which are base stations, via millimeter wave communications.

[0005] By using IAB technology, it is possible to expand area coverage at a lower cost than conventional wired communications using optical fiber, etc.

[0006] Up until now, 3GPP has been formulating specifications for border IAB nodes up to Rel-17.

[0007] As disclosed in Patent Document 2, a border IAB node, which has been discussed since Rel-17, is an IAB node that connects to both IAB networks managed by different IAB donors. A border IAB node is controlled by a single IAB donor. Therefore, IAB nodes connected below the border IAB node connect to the IAB network managed by the IAB donor that controls the border IAB node.

[0008] The advantage of a boundary IAB node is that an IAB donor that controls the boundary IAB node can communicate with a device connected to the boundary IAB node via an IAB network managed by another IAB donor. This allows the IAB donor that controls the boundary IAB node to reduce inconvenience when a wireless link failure occurs in the network it manages. In other words, by using another IAB network, it becomes possible to communicate while avoiding the wireless link failure.

[0009] Patent Publication No. 2019-534625 U.S. Patent Publication No. 2022 / 0394571

[0010] As 5G (5th Generation Mobile Communication System) becomes more widespread, IAB nodes, especially mobile IAB nodes, are expected to become more widely used. In this case, it is possible that not all IAB nodes will be able to function as border IAB nodes due to device specifications, resource limitations, etc.

[0011] The present invention has been made in consideration of at least one of the above-mentioned problems, and an object of one aspect of the present invention is to provide a mechanism that enables identification of an IAB node that can operate as a border IAB node.

[0012] A communication device according to one aspect of the present invention is characterized by having: a determination means for determining whether a node functioning as an IAB node forming one IAB network is capable of operating as a border IAB node, which is an IAB node that connects to both the one IAB network and another IAB network; and a transmission means for transmitting a communication message according to the determination result based on the determination result.

[0013] According to one aspect of the present invention, it is possible to provide a mechanism that makes it possible to identify IAB nodes that can operate as border IAB nodes.

[0014] 1 is a hardware block diagram constituting an IAB node and an IAB donor. FIG. 2 is a software functional block diagram of an IAB node and an IAB donor. FIG. 3 is a configuration example of a backhaul communication system (a network using backhaul communication) in a first embodiment. FIG. 4 is an example of a boundary IAB node processing sequence for an IAB node in the 3GPP standard. FIG. 5 is a schematic flowchart showing an example of an RRC message generation process of an IAB node in the first embodiment. FIG. 6 is an example of a sequence for determining whether boundary IAB node processing is necessary for an IAB donor in the first embodiment. FIG. 7 is an example of a sequence for network participation processing of an IAB node in the 3GPP standard. FIG. 8 is an example of a sequence for determining whether boundary IAB node processing is necessary for an IAB donor in a second embodiment.

[0015] Each embodiment will be described in detail below with reference to the accompanying drawings.

[0016] Each embodiment described below will be mainly described as an application example in 5G, but each embodiment is not limited to 5G and can also be applied to other next-generation networks such as LTE (Long Term Evolution), 4G, and 6G and later.

[0017] 1 is a block diagram showing an example of the hardware configuration of an IAB node according to a first embodiment. The hardware configuration of an IAB donor may be similar.

[0018] The hardware configuration 101 of the IAB node includes a control unit 102 , a storage unit 103 , a wireless communication unit 104 , and a communication antenna control unit 105 .

[0019] The control unit 102 is configured with one or more processors such as a CPU or MPU, and controls the entire communication device by executing a control program read into the RAM, which is the storage unit 103. Note that each process performed by the control unit 102, which will be described in the flowcharts below, can also be realized using a hardware circuit such as an ASIC or FPGA. Note that ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array. Also, the processes described in the flowcharts below can be realized by cooperation between a hardware circuit and a processor such as a CPU or MPU.

[0020] The storage unit 103 stores information used for control by the control unit 102 and information related to communication. For example, the storage unit 103 stores a control program executed by the control unit 102, and various information such as cell information, connected terminal information, IAB routing information, and location information.

[0021] The memory unit 103 may include a main memory unit and an auxiliary memory unit. The main memory unit may be, for example, a read-only memory (ROM) or a random access memory (RAM). The main memory unit may store or temporarily store programs and data such as an operating system (OS), which is basic software executed by the control unit 102, and application software. The auxiliary memory unit may be, for example, a hard disk drive (HDD) or a solid state drive (SSD), and may store data related to application software. For example, a control program stored in a non-volatile storage area is expanded into random access memory (RAM) and executed by a processor constituting the control unit 102. In this way, the control unit 102 and the memory unit 103 may function as a so-called computer.

[0022] The storage unit 103 may include a recording medium that stores a predetermined program. The program stored in this recording medium may be installed via a drive device or the like, and the installed predetermined program may be executable by the control unit 102. Various types of recording media can be used as the recording medium. For example, the recording medium may be a recording medium that records information optically, electrically, or magnetically, such as a CD (Compact Disc)-ROM, a flexible disk, or a magneto-optical disk. The recording medium may also be a semiconductor memory that records information electrically, such as a ROM or a flash memory. Note that the recording medium does not include a carrier wave.

[0023] The wireless communication unit 104 performs cellular network communication such as LTE and 5G that conform to the 3GPP standard.

[0024] The communication antenna control unit 105 controls the antenna used for wireless communication performed by the wireless communication unit 104 .

[0025] 2 is a block diagram showing an example of the software functional block configuration of an IAB node that executes the communication control function. The software configuration of an IAB donor may be similar.

[0026] The software configuration 201 of the IAB node is stored in the storage unit 103 and executed by the control unit 102.

[0027] The software configuration 201 includes a signal transmitting unit 202 , a signal receiving unit 203 , a data storage unit 204 , a connection control unit 205 , an RRC message detecting unit 206 , an RRC message generating unit 207 , and a communication control unit 208 .

[0028] The signal transmitting unit 202 and the signal receiving unit 203 perform cellular network communication such as LTE or 5G that conforms to the 3GPP standard with a terminal device such as a UE.

[0029] The data storage unit 204 stores and holds the software itself, IAB routing information, information on connected terminals, location information, movement route information, and the like.

[0030] The connection control unit 205 controls the antenna for wireless communication performed by the wireless communication unit 104 .

[0031] The RRC message detection unit 206 detects RRC messages from IAB nodes located in the vicinity (hereinafter also referred to as "neighboring IAB nodes"), UEs, and IAB donors. RRC is an abbreviation for Radio Resource Control.

[0032] The RRC message generation unit 207 generates an RRC message to be transmitted to a neighboring IAB node, a UE, and an IAB donor.

[0033] The communication control unit 208 connects to and disconnects from networks such as LTE and 5G.

[0034] FIG. 3 shows an example of the configuration of a backhaul communication system (a network using backhaul communication) in this embodiment.

[0035] In backhaul communication, communication from an IAB donor, which is the relay source, is relayed in order from a parent node to a child node. For example, an IAB donor provides backhaul communication to an IAB node connected to the donor, and in this case, the IAB donor is the parent node, and the IAB node connected to the IAB donor is the child node.

[0036] 3, the communication system includes IAB donors 302 and 303 connected to a core network (CN) 301. IAB donors 302 and 303 provide connections to CN 301 via backhaul communication to IAB nodes connected to them as child nodes (i.e., provide backhaul communication).

[0037] The CN and the IAB donor are generally connected by a wired connection over an IP (Internet Protocol) network, and the interface between the IAB donors is the Xn interface defined in 3GPP TS38.420.

[0038] An IAB node 304 is connected as a child node to the IAB donor 302. Furthermore, an IAB node 305 and an IAB node 306 are connected as child nodes to the IAB node 304.

[0039] A UE 307 communicating within a cell area 308 of a cell served by an IAB node 306 can connect to the CN 301 via each IAB donor or IAB node. In the communication system shown in Figure 3, the UE 307 connects to the CN 301 via the IAB node 306.

[0040] In addition, other IAB donors and IAB nodes other than IAB node 306 can also provide connections to CN 301 for UEs in their cell areas.

[0041] On the other hand, IAB node 310 is connected as a child node to IAB donor 303. Furthermore, IAB node 311 is connected as a child node to IAB node 310. In this way, IAB donor 302 and IAB donor 303 each build their own IAB network.

[0042] The arrangement / configuration of each communication device in the communication system shown in FIG. 3 is an example, and the following description can be applied to other arrangements / configurations.

[0043] 3 is a communication device in a 5G access network also called a New Radio (NR) access network. The radio base station devices (IAB donors and IAB nodes) may also be referred to as gNBs. The following description is also applicable to configurations using other next-generation networks.

[0044] 4A shows a typical sequence when an IAB node according to the 3GPP standard operates as a border IAB node, as defined in 3GPP TS 38.401.

[0045] In this sequence diagram, a case is illustrated in which the IAB node 306 operates as a boundary IAB node, and the IAB node 310, the IAB donor 303, is selected as the second connection destination.

[0046] IAB node 306 is currently connected to CN 301 via IAB node 304 and IAB donor 302 .

[0047] UE 307 is connected to IAB node 306. In this case, UE 307 transmits and receives downlink data S420 and uplink data S421 to CN 301 via IAB node 306, IAB node 304, and IAB donor 302.

[0048] First, the NR-DC connection establishment process for the boundary IAB node shown in S401 is performed between the IAB node 306 and the CN 301. The "DC" in NR-DC is an abbreviation for Dual Connectivity. The IAB node 306 collects information on surrounding IAB nodes and base stations and transmits the information on the currently connected upper node as a Measurement Report. The IAB donor 302, which is the upper node that receives the Measurement Report, selects a second connection destination to which the IAB node 306 will establish a new connection based on the Measurement Report, etc. Then, the IAB donor 302 and other devices cooperate to perform the NR-DC connection establishment process, which adds the second connection destination selected by the IAB donor 302 as a secondary node.

[0049] This processing sequence is defined in 3GPP TS37.340 and is performed for the MT (Mobile Termination) part of the border IAB node 306.

[0050] Next, in S402, the IAB donor 302 transmits an IAB TRANSPORT MIGRATION MANAGEMENT REQUEST message to the IAB donor 303, which is the second connection destination.

[0051] Upon receiving this request, the IAB donor 303 transmits a DL RRC MESSAGE TRANSFER message, which corresponds to an RRC Reconfiguration message, to the IAB node 310 in S403.

[0052] Next, in S404, the IAB node 310 transmits an RRCReconfiguration message to the boundary IAB node 306 to which it is to connect.

[0053] In response to the above message, the boundary IAB node 306 transmits an RRCReconfigurationComplete message to the IAB node 310 in S405. In response to this, the IAB node 310 transmits a UL RRC MESSAGE TRANSFER message corresponding to the RRCReconfigurationComplete message to the IAB donor 303 (S406).

[0054] Through the processing up to this point, the border IAB node 306 is ready to connect to the IAB node 310 and IAB donor 303, which will be the second communication path. Then, in S407, wireless layer and backhaul connection processing is performed between the border IAB node 306 and the IAB node 310 and IAB donor 303, which will be the second connection destination.

[0055] After the above process is completed, in S408, the IAB donor 303 sends an IAB TRANSPORT MIGRATION MANAGEMENT RESPONSE to the IAB donor 302 as a response to S402.

[0056] Next, in S409, offload processing of uplink and downlink data is performed.

[0057] After the above process is completed, the IAB donor 302 sends an IAB TRANSPORT MIGRATION MANAGEMENT REQUEST message to the IAB donor 303 that is the offload destination (S410). The sending of this message corresponds to the sending of the completion of the offload process. In response, the IAB donor 303 sends an IAB TRANSPORT MIGRATION MANAGEMENT RESPONSE message to the IAB donor 302 (S411).

[0058] As a result of the series of processes up to this point, as shown in S422 and S423, IAB node 306 operates as a boundary IAB node, and uplink and downlink data can be sent and received via the second communication path via IAB node 310.

[0059] Furthermore, these processes may be repeated as necessary in S412. In this case, since the NR-DC connection has already been established in S401, the processes from S402 to S411 are carried out.

[0060] 4A is a process performed when the IAB node 306 is a mobile IAB node and operates as a border IAB node. By allowing a moving mobile IAB node to function as a border IAB node, connection switching during movement can be performed seamlessly.

[0061] However, as 5G becomes more widespread, it is expected that IAB nodes, especially mobile IAB nodes, will become widely used. In this case, it is unlikely that all IAB nodes will be able to become border IAB nodes due to device specifications, resource limitations, etc.

[0062] Furthermore, if all nodes operate as boundary IAB nodes, the amount of processing between the IAB donor and the CU (Central Unit) will also increase, which may increase the system load.

[0063] Therefore, with reference to the following FIGS. 4B and 5, a mechanism will be described in which the IAB donor 302 can explicitly distinguish IAB nodes that do not operate as border IAB nodes.

[0064] 4B is a schematic flowchart illustrating an example of an RRC message generation process executed by the mobile IAB node 306. The process illustrated in FIG. 4B may be executed at any timing when the mobile IAB node 306 is not operating as a border IAB node. For example, the process illustrated in FIG. 4B may be executed before transmitting the RRCSetupComplete message in step S605 of FIG. 6 (described later).

[0065] First, at S450, the mobile IAB node 306 determines whether it can operate as a border IAB node. Whether it can operate as a border IAB node may be determined based on any criteria. For example, the criteria may include whether the location of the mobile IAB node 306 is within a location range in which it can operate as a border IAB node.

[0066] If the mobile IAB node 306 is capable of operating as a boundary IAB node, in step S451 the mobile IAB node 306 includes, in the RRC message, predetermined information indicating that the node itself is capable of operating as a boundary IAB node. The predetermined information is information indicating whether the node itself is capable of operating as a boundary IAB node. On the other hand, if the node itself is not capable of operating as a boundary IAB node, in step S452 the mobile IAB node 306 includes, in the RRC message, predetermined information indicating that the node itself is not capable of operating as a boundary IAB node. Note that in other embodiments, if the node itself is not capable of operating as a boundary IAB node, the mobile IAB node 306 may not include the predetermined information itself in the RRC message in step S452.

[0067] According to the process shown in FIG. 4B, the IAB donor 302 side receiving the RRC message can determine whether the mobile IAB node 306 can operate as a border IAB node based on predetermined information.

[0068] FIG. 5 is a schematic flow chart illustrating the process performed at the IAB donor 302 in conjunction with the process illustrated in FIG. 4B.

[0069] This flowchart is described assuming that the IAB node 306 operating as a border IAB node is a mobile IAB node that is intended to move.

[0070] First, in F501, the mobile IAB node 306 joins the network topology via the IAB node 304, and the associated processing shown in FIG. 6 is executed.

[0071] 6 shows an example of a sequence when the mobile IAB node 306 joins a 5G network. This sequence is an example of a 5G network connection sequence for a general IAB node according to the 3GPP standard defined in 3GPP TR38.401.

[0072] First, the mobile IAB node 306 sends an RRCSetupRequest message to the IAB node 304 in S601.

[0073] Upon receiving the message, the IAB node 304 sends an initial UL RRC message to the IAB donor 302 in step S602 if the IAB node 304 wants the source mobile IAB node 306 to join the 5G network.

[0074] When the IAB donor 302 receives this message, it sends a DL RRC message (S603) to the IAB node 304, and the IAB node 304 sends an RRCSetup message (S604) to the mobile IAB node 306.

[0075] In response to this, the mobile IAB node 306 transmits an RRCSetupComplete message to the IAB node 304 in S605. Then, the IAB node 304 transmits an UL RRC message to the IAB donor 302 in S606 to relay the RRCSetupComplete message.

[0076] The IAB donor 302 sends a context setup request message to the IAB node 304 in step S607 to establish a context for the mobile IAB node 306 that has connected to the IAB donor 302.

[0077] In response, the IAB node 304 sends a SecurityModeCommand message to the mobile IAB node 306 in S608.

[0078] After sending this message, the IAB node 304 asynchronously sends a context setup response message to the IAB donor 302 in step S609.

[0079] In parallel with this, the mobile IAB node 306 sends a SecurityModeComplete message to the IAB node 304 at S610. The IAB node 304 relays the SecurityModeComplete message and sends a UL RRC message to the IAB donor 302 at S611.

[0080] Upon receiving this, the IAB donor 302 includes the RRCConfiguration message in a DL RRC message and transmits it to the IAB node 304 in S612. The IAB node 304 relays the DL RRC message and transmits the RRCConfiguration message to the mobile IAB node 306 in S613.

[0081] The mobile IAB node 306 transmits an RRCConfigurationComplete message as a response to the RRCConfiguration message to the IAB node 304 in S614. The IAB node 304 relays this message and transmits a UL RRC message to the IAB donor 302 in S615.

[0082] In this embodiment, the mobile IAB node 306 transmits the RRCSetupComplete message shown in S605 including predetermined information, as described above with reference to FIG. 4B. As described above, the predetermined information is information indicating whether the local node can operate as a boundary IAB node. In this embodiment, the predetermined information is an information field and a parameter indicating whether the local node can operate as a boundary IAB node.

[0083] The RRCSetupComplete message format is defined in 3GPP TS 38.331. In this case, predetermined information may be included in the RRCSetupComplete-IEs parameters or extension parameters of the RRCSetupComplete-IEs.

[0084] Furthermore, instead of or in addition to the RRCSetupComplete message, predetermined information may be included in an RRCSetupRequest message or an RRCReconfigurationComplete message.

[0085] Next, in F502, the IAB donor 302 determines whether predetermined information is included in the RRCSetupComplete message. As described above, the predetermined information may be included in the RRCSetupRequest message instead of or in addition to the RRCSetupComplete message. In this case, in F502, the IAB donor 302 may determine whether predetermined information is included in the RRCSetupRequest message.

[0086] More specifically, for F502, the IAB donor 302 determines whether the RRCSetupComplete message includes an information field indicating whether it is operable as a border IAB node.

[0087] If it is determined in the determination process of F502 that the information field indicating whether or not the device can operate as a boundary IAB node is not included, it is determined that the series of processes for operating as a boundary IAB node shown in Figure 4A is unnecessary. In other words, if the predetermined information indicates that the device cannot operate as a boundary IAB node, the process of F504 is not performed and the system returns to normal operation.

[0088] Furthermore, if it is determined in the determination process of F502 that the information field indicating whether or not the node can operate as a border IAB node is included, it is determined in F503 whether or not the currently participating mobile IAB node 306 can operate as a border IAB node.

[0089] More specifically, a parameter included in the information field indicating whether the node is operable as a border IAB node is checked. The parameter may be a binary value, such as 1 for operable and 0 for inoperable. In another embodiment, the information field may be set only when the node is operable.

[0090] If the determination process in F503 determines that the currently joining mobile IAB node 306 cannot operate as a boundary IAB node, it determines that the series of processes shown in Figure 4A for operating as a boundary IAB node is unnecessary. In other words, if the predetermined information indicates that the mobile IAB node 306 cannot operate as a boundary IAB node, the process in F504 is not performed and the system returns to normal operation.

[0091] If the determination process in step F503 determines that the currently participating mobile IAB node 306 can operate as a border IAB node, the process shown in Fig. 4A is required to operate the mobile IAB node as a border IAB node. That is, if the predetermined information indicates that the mobile IAB node 306 can operate as a border IAB node, the IAB donor 302 performs the process shown in Fig. 4A to operate the mobile IAB node as a border IAB node in step F505.

[0092] In this manner, according to this embodiment, an IAB node transmits information about whether it can operate as a boundary IAB node to the IAB donor, and the IAB donor 302, upon receiving the information, can determine whether to perform the process shown in Fig. 4A. This allows the process shown in Fig. 4A to be performed only on IAB nodes that can operate as boundary IAB nodes. As a result, the inconvenience (the increase in system load described above) that can occur when all IAB nodes operate as boundary IAB nodes can be reduced.

[0093] Next, other embodiments that may be realized instead of the first embodiment described above will be described. Detailed descriptions of configurations that may be similar to the first embodiment described above will be omitted below.

[0094] [Second Embodiment] In the first embodiment described above, an IAB node transmits predetermined information when it joins the network topology. The IAB donor then uses the predetermined information to determine whether or not to perform the series of processes shown in FIG. 4A to operate as a border IAB node. In contrast, the second embodiment utilizes the timing when an IAB node transmits surrounding environment information to an IAB donor, rather than the timing when the IAB node joins the network topology. Specifically, this is as follows.

[0095] As specified in 3GPP TS 38.331, an IAB node periodically transmits collected ambient environment information to an IAB donor in a Measurement Report message.

[0096] This message is used by the IAB donor to configure the network topology. After receiving the Measurement Report message, the IAB donor sends an RRCReconfiguration message to the source IAB node as needed to reconfigure the network topology. This causes the IAB donor to hand over.

[0097] The series of processes for operating as a border IAB node shown in Fig. 4A may be performed at this timing. In this case, predetermined information is included in the Measurement Report message and transmitted.

[0098] This allows the IAB donor to use the Measurement Report message to determine whether or not to perform the series of processes shown in FIG. 4A to operate as a border IAB node.

[0099] FIG. 7 shows a flowchart of the IAB donor 302 in this embodiment.

[0100] In the first embodiment, the IAB node 306 is a mobile IAB node that is assumed to move, but in this embodiment, it is described as an IAB node that does not move. However, it goes without saying that it may also be a mobile IAB node that is assumed to move.

[0101] First, in F701, the IAB donor 302 receives a MeasurementReport message including predetermined information from the IAB node 306 via the IAB node 304. The MeasurementReport message format is defined in 3GPP TS38.331. In this case, the predetermined information can be included in parameters in the MeasResults field in the MeasurementReport-IEs field.

[0102] Next, the IAB donor 302 performs a check of the current network topology in F702 and determines whether a network topology change of the IAB node 306 is necessary in F703.

[0103] If it is determined in F703 that no change in the network topology is necessary, the system returns to normal operation.

[0104] Next, if it is determined in F703 that a change in the network topology is necessary, it is determined in F704 whether the IAB node 306 needs to operate as a boundary IAB node.

[0105] If it is determined in F704 that the IAB node 306 does not need to operate as a boundary IAB node, the system returns to normal operation. However, in this case, it may be determined that a handover to another node is necessary even though it does not need to operate as a boundary IAB node. In other words, a handover process for the IAB node (not shown) may be executed.

[0106] If it is determined in F704 that it is necessary to operate as a boundary IAB node, it is determined in F705 whether or not predetermined information is included in the Measurement Report message that is being received.

[0107] More specifically, it is determined whether an information field indicating whether or not the node can operate as a border IAB node is included.

[0108] If it is determined in the determination process of F705 that the information field indicating whether or not the node can operate as a boundary IAB node is not included, it is determined that the series of processes for operating as a boundary IAB node shown in Fig. 4A is unnecessary. In this case, the process of F707 is not performed and the system returns to normal operation.

[0109] If it is determined in the determination process of F705 that the information field on whether or not the node can operate as a boundary IAB node is included, it is determined in F706 whether or not the IAB node can operate as a boundary IAB node.

[0110] More specifically, a parameter check is performed on the information field to determine whether the node can operate as a border IAB node.

[0111] If the judgment process in F706 determines that the IAB node cannot operate as a boundary IAB node, it is determined that the series of processes shown in Figure 4A to operate as a boundary IAB node is unnecessary, and the process in F707 is not performed and the system returns to normal operation.

[0112] Furthermore, if the judgment process in F706 determines that the IAB node can operate as a boundary IAB node, a series of processes shown in Figure 4A are required to operate it as a boundary IAB node, so this process is carried out in F708.

[0113] The second embodiment also provides the same effects as the first embodiment described above.

[0114] [Third Embodiment] In the first and second embodiments described above, the transmission means for transmitting predetermined information and the timing for determining whether or not to perform the series of processes for the IAB donor to operate as a border IAB node shown in FIG. 4A have been described.

[0115] Here, the predetermined information (information indicating whether an IAB node can operate as a boundary IAB node) is mainly transmitted using an RRC message. However, the predetermined information may be transmitted by including it in broadcast information of the IAB node, such as a beacon.

[0116] Broadcast information includes SSB, MIB, SIB, etc., and the information transmitted by these may include predetermined information (information on whether the source IAB node can operate as a boundary IAB node). Note that SSB is an abbreviation for Synchronization Signal Block. MIB is an abbreviation for MasterInformationBlock. SIB is an abbreviation for SystemInformationBlock.

[0117] In particular, as for the SIB, various information formats are defined for surrounding cell information, idle information, side link related information, etc., as specified in 3GPP TS 38.331. A new format for defining predetermined information may be created in addition to these definitions and transmitted as a new SIB.

[0118] Alternatively, a field indicating predetermined information may be added to an existing information definition format.

[0119] Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments.

[0120] For example, in the above-described embodiment, a determination is made as to whether or not to perform a series of processes that allow the IAB donor to operate as a border IAB node, as shown in Figures 5 and 7. If it is determined in the determination processes of F502 and F705 that the predetermined information (the information field indicating whether or not the IAB donor can operate as a border IAB node) is not included, the system returns to normal operation. In other words, as shown in F504 and F707, the connection process as a border IAB node is not performed.

[0121] On the other hand, if the information transmitted from the IAB node includes information indicating whether or not the IAB donor will perform a series of processes to operate as a border IAB node (another example of predetermined information), the system may perform connection processing as a border IAB node.

[0122] In this case, if it is determined in the judgment processes of F502 and F705 that the information field indicating whether or not the node can operate as a boundary IAB node is not included, a series of processes may be performed in F505 and F708 to operate the node as a boundary IAB node.

[0123] In addition, the flowcharts for the process of determining whether to perform a series of processes to cause an IAB donor to operate as a border IAB node are shown in the first embodiment as an example of a mobile IAB node, and in the second embodiment as an example of an IAB node that does not move. However, the determination processes shown in Figures 4A and 7 may be performed in a different order or with additional determination processes. For example, the process of determining whether the source IAB node shown in F704 needs to operate as a border IAB node may be performed as a pre-processing step of F502.

[0124] Furthermore, in the third embodiment, a method of including predetermined information in broadcast information of an IAB node, such as a beacon, and transmitting the information is exemplified as a transmission means other than an RRC message. However, as an alternative method, the information may be transmitted using a BAP (Backhaul Adaptation Protocol) message. The BAP message specifications are defined in 3GPP TS38.340. In this case, predetermined information (an information field and a parameter indicating whether the source IAB node can operate as a border IAB node) may be included in a data PDU (Protocol Data Unit) and a control PDU and transmitted.

[0125] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0126] This application claims priority based on Japanese Patent Application No. 2023-096499, filed on June 12, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A communication device comprising: a determination means for determining whether a node functioning as an IAB node forming one IAB (Integrated Access and Backhaul) network is capable of operating as a border IAB node, which is an IAB node connecting to both the one IAB network and another IAB network; and a transmission means for transmitting a communication message according to the determination result of the determination means.

2. The communication device according to claim 1, wherein the communication message includes predetermined information indicating whether the node is capable of operating as the border IAB node.

3. The communication device according to claim 2, wherein the predetermined information includes a parameter value representing the result of the determination.

4. A communication device according to any one of claims 1 to 3, characterized in that it is movable as a mobile IAB node.

5. A communication device functioning as an IAB donor forming one IAB (Integrated Access and Backhaul) network, comprising: a receiving means for receiving a communication message from another communication device functioning as an IAB node; and a determining means for determining, based on the communication message, whether the other communication device is capable of operating as a border IAB node, which is an IAB node connecting to both the one IAB network and another IAB network.

6. The communication device according to claim 5, wherein said determination means determines whether said other communication device is capable of operating as a border IAB node based on whether or not said communication message contains specified information.

7. The communication device according to claim 6, characterized in that, when the communication message contains the specified information, the determination means determines whether the other communication device is capable of operating as a border IAB node based on the specified information.

8. A communication device according to claim 6 or 7, characterized in that the predetermined information includes a parameter value indicating whether the other communication device is capable of operating as a border IAB node.

9. The communication device according to any one of claims 1 to 8, wherein the communication message is a Radio Resource Control (RRC) message, a Backhaul Adaptation Protocol (BAP) message, or a Measurement Report message.

10. The communication device according to any one of claims 1 to 8, wherein the communication message is an RRC message, and the RRC message is an RRC SetupComplete message or a Measurement Report message.

11. A control method for controlling communications, comprising: a determination step for determining whether a node functioning as an IAB node forming one IAB (Integrated Access and Backhaul) network is capable of operating as a border IAB node, which is an IAB node connecting to both the one IAB network and another IAB network; and a transmission step for transmitting a communication message according to the determination result of the determination step.

12. A program that causes a computer to execute a determination process for determining whether a node functioning as an IAB node forming one IAB (Integrated Access and Backhaul) network is capable of operating as a border IAB node, which is an IAB node that connects to both the one IAB network and another IAB network, and a transmission process for transmitting a communication message according to the determination result based on the determination result of the determination process.

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