Communication device, control method, and program

Abstract

A communication apparatus is disclosed, the communication apparatus having an MBSR (Mobile Base Station Relay) operation function. The communication apparatus is operable in a first mode in which only another communication apparatus having an MBSR operation function is connected to a DU (Distributed Unit) of the communication apparatus, the first mode being a mode in which communication between the another communication apparatus and an IAB (Integrated Access and Backhaul) donor is relayed.

Description

Technical Field

[0001] This disclosure relates to communication devices, control methods, and procedures. Background Technology

[0002] Cellular communication standards are established by the 3rd Generation Partnership Project (3GPP (registered trademark)). In the 3GPP cellular communication standards (hereinafter referred to as "3GPP standards"), Integrated Access and Backhaul (IAB), which integrates access links and backhaul links, is being standardized (see PTL 1).

[0003] In an IAB, radio resources used for the access link between a base station (gNB) and a user terminal (UE) are also used in the backhaul link. For example, radio resources in millimeter-wave bands, such as the 28 GHz band, can be used in an IAB. The use of an IAB allows relay equipment (IAB nodes) to relay communication between base station equipment (IAB donors) and terminal equipment via a wireless link, thereby enabling the extension of area coverage at a lower cost compared to wired links such as fiber optics.

[0004] Until Release 17, which was the standardization phase of 3GPP, specifications were established for fixed base stations (IAB nodes that do not have mobility).

[0005] Currently, 3GPP has reached Release 18, where vehicular relays are being actively discussed as a use case. Furthermore, discussions are actively underway regarding mobile IABs or mobile base station relays (MBSRs) to develop specifications for the architecture and protocols used to implement such use cases. In millimeter-wave IABs, MBSRs face challenges in maintaining connectivity (communication service coverage) with IAB donors and IAB nodes in locations where radio waves from IAB nodes are difficult to reach due to obstacles (such as urban areas with buildings).

[0006] Citation List

[0007] Patent documents

[0008] PTL 1: PCT Japanese Translation Patent Publication No. 2019-534625 Summary of the Invention

[0009] Technical issues

[0010] 3GPP Release 18 is being standardized to limit the further connection of IAB nodes under MBSRs in order to simplify MBSR participation in IAB topologies. That is, MBSRs only support single-hop configurations. In contrast, enabling multi-hop configurations where another MBSR is further connected under another MBSR can enhance path flexibility. In this case, flexible expansion of cell coverage is expected.

[0011] The present invention was made in view of the above circumstances. One aspect of the object of the present invention is to provide a mechanism capable of providing stable communication services to MBSRs located in areas where radio waves have difficulty reaching.

[0012] Solution to the problem

[0013] According to one aspect of the invention, a communication device is a communication device having MBSR (Mobile Base Station Relay) operation function, wherein the communication device is operable in a first mode in which only one other communication device is connected to the communication device's DU (Distributed Unit), the other communication device having MBSR operation function, and the first mode is a mode in which communication between the other communication device and an IAB (Integrated Access and Backhaul) donor is relayed.

[0014] Advantages of the invention

[0015] One aspect of the present invention can provide a mechanism for providing stable communication services to MBSRs located in areas difficult to reach by radio waves. Attached Figure Description

[0016] Figure 1 This is a diagram illustrating an example of a communication system.

[0017] Figure 2A This is a diagram illustrating the software configuration of MBSR.

[0018] Figure 2B This is a diagram illustrating the hardware configuration of the MBSR.

[0019] Figure 2C This is a block diagram illustrating an example of the hardware configuration of an IAB donor according to this embodiment.

[0020] Figure 2D This is a block diagram illustrating an example of the hardware configuration of an IAB donor according to this embodiment.

[0021] Figure 3 This is a flowchart illustrating the process in this embodiment where the IAB donor generates an instruction to change the mode to relay mode.

[0022] Figure 4This is a flowchart illustrating an example of pattern determination for a relay candidate MBSR.

[0023] Figure 5 The diagram illustrates the sequence in which an IAB donor requests a relay candidate MBSR (without a UE) to perform a relay.

[0024] Figure 6 The diagram illustrates the Relay Request Message (RRC) format (IAB Donor to Relay Candidate MBSR).

[0025] Figure 7 The diagram illustrates the relay request message format BAP (IAB donor to relay candidate MBSR).

[0026] Figure 8A This is a flowchart illustrating an example of MBSR processing in this embodiment.

[0027] Figure 8B This is another flowchart illustrating an example of MBSR processing in this embodiment.

[0028] Figure 9 The diagram illustrates the sequence of relay requests from a disconnected MBSR to a candidate MBSR (without a UE) to perform a relay.

[0029] Figure 10A This is an explanatory diagram of an example of a relay request message format broadcast (from a disconnected MBSR to a relay candidate MBSR).

[0030] Figure 10B This is an explanatory diagram of another example of a relay request message format broadcast (from a disconnected MBSR to a relay candidate MBSR).

[0031] Figure 11 The diagram illustrates the Relay Request Message (RRC) (unicast) format (from a disconnected MBSR to a relay candidate MBSR).

[0032] Figure 12 The diagram illustrates the sequence of new DU execution relays by an IAB donor requesting a relay candidate MBSR (with a UE).

[0033] Figure 13 The diagram illustrates the sequence of relaying a new DU to a disconnected MBSR request relay candidate MBSR (with UE).

[0034] Figure 14 This is a flowchart of another example of pattern determination for relay candidate MBSRs.

[0035] Figure 15 The diagram illustrates the sequence in which an IAB donor requests a relay candidate MBSR (with a UE) to perform a relay.

[0036] Figure 16The diagram illustrates the sequence of relay requests from a disconnected MBSR to a candidate MBSR (with a UE) to perform a relay. Detailed Implementation

[0037] The embodiments will be described in detail below with reference to the accompanying drawings. In the following description, TS "Number" "" indicates the technical specification number in the 3GPP standard.

[0038] 3GPP Release 18 is being standardized to restrict IAB nodes from being further connected under MBSRs in order to simplify MBSR participation in IAB topologies. That is, MBSRs only support single-hop configurations. In contrast, enabling the creation of multi-hop configurations where another MBSR is further connected under an MBSR can enhance path flexibility and is expected to allow for flexible expansion of cell coverage areas. Therefore, the purpose of the following embodiments is to provide specific mechanisms for implementing IAB topologies with multi-hop configurations.

[0039] In specific use cases, if an MBSR disconnects from its IAB donor and fails to detect any other connectable nodes, it cannot connect to another MBSR even if that MBSR is nearby. Therefore, the UE under the MBSR cannot perform data communication (i.e., a service interruption occurs) until that MBSR discovers its parent node. However, the specification, which only supports single-hop MBSRs, lacks a means (triggering) to request another MBSR to perform relay operations. Therefore, one objective of the following embodiments is to provide a mechanism to trigger another MBSR to begin operating as a relay node for an MBSR that does not have a connectable parent node. As another aspect, one objective of the following embodiments is to enhance the convenience of cellular communication.

[0040] Figure 1 The illustration depicts a mobile wireless communication system, such as a 5G system, which includes a radio integrated access and backhaul network supporting an MBSR for communication system 100. Although this document will primarily describe 5G, the invention can also be applied to systems other than 5G (e.g., 5G Advanced, 6G, etc.).

[0041] The communication system 100 includes multiple UEs 120 to 123, a core network 150, a main base station 110, and MBSRs 101 and 102 installed on vehicles 111 and 112. Vehicles 111 and 112 can each be of any form, such as, for example, a bus, train, taxi, or car. Vehicle 113, MBSR 103, and remote UE 123 represent the moved vehicle 112, MBSR 102, and remote UE 122, respectively. That is, vehicle 113, MBSR 103, and remote UE 123 are exactly the same as vehicle 112, MBSR 102, and remote UE 122, respectively. However, they are distinguished for the sake of description, and the distinction is not necessarily consistent with the disconnection timing described below. The main base station 110 (also referred to as IAB donor 110) is connected to the core network 150 via a wired link 140 (preferably fiber optic or any other wired component). In the embodiment described below, IAB donor 110 is a 5G base station (gNB) with additional functions for supporting IAB functions as defined in the 3GPP TS38.300 v17.2.0 specification.

[0042] MBSRs 101 and 102 (also known as mobile IAB nodes) are installed on vehicles 111 and 112 and provide network coverage and capacity expansion. IAB donor 110 can communicate not only with UEs inside the vehicle (such as remote UEs 121 and 122 (123)) but also with UEs outside the vehicle (such as UE 120). Therefore, IAB donor 110, along with MBSRs 101 and 102, forms a backhaul network, IAB network, or IAB topology accommodating UEs 121 and 122. In the following description, the terms "IAB network" and "IAB topology" are used interchangeably. IAB specifications are defined in several 3GPP standard documents, such as the following:

[0043] - TS 38.300 RAN architecture (V17.2.0)

[0044] - TS 38.321 MAC Protocol (V17.2.0)

[0045] - TS 38.331 Radio Resource Control (RRC) Protocol (V17.2.0)

[0046] - TS 38.340 Backhaul Adapter Protocol Layer (V17.2.0)

[0047] - TS 38.401 RAN Architecture (V17.2.0)

[0048] - TS 38.423 Xn Application Protocol (V17.2.0)

[0049] - TS 38.473 F1 Application Protocol (V17.2.0)

[0050] Reference Figure 1 An overview describing the occurrence of problems up to the point where a single hop of MBSR occurs.

[0051] IAB donor 110 is wirelessly connected to MBSR 101 via wireless backhaul link 141, and similarly wirelessly connected to MBSR 102 via wireless backhaul link 142. IAB donor 110 can perform data communication with UE 121 in vehicle 111 equipped with MBSR 101, and can perform data communication with UE 122 in vehicle 112 equipped with MBSR 102.

[0052] If vehicle 112 moves to the position of vehicle 113 by moving in the direction of arrow 160, MBSR 102 installed on the vehicle moves to MBSR 103, and UE 122 on the vehicle moves to UE 123. In that case, MBSR 103 may be hidden behind an obstacle 130 such as a building. In this situation, the radio wave strength of the radio backhaul link 142 with IAB donor 110 gradually attenuates, eventually leading to radio link disconnection and radio link failure (RLF).

[0053] Following the RLF, MBSR 103 searches for IAB donor 110, which is connected to it as a parent node, and attempts to establish a connection. However, obstacles 130 and 131 block the connection. As a result, UE 123 is also unable to perform data communication under MBSR 103 (i.e., a service interruption state occurs). By searching for connectable base stations (including IAB donors and IAB nodes) as parent nodes, MBSR 103 can detect MBSR 101, which has high receive power, as a parent node. Moreover, in this case, if MBSR 101 only supports single hops, then MBSR 101 will reject connection requests from MBSR 103. As a result, the service interruption state in MBSR 103 persists.

[0054] The mechanisms that can at least partially solve such problems will be described in detail below through examples.

[0055] Figure 2A This is a hardware functional block diagram of MBSR 102 in the embodiment described below. Although the configuration of MBSR 102 will now be described, this also applies to MBSR 101.

[0056] MBSR 102 includes hardware including a control unit 201, a storage unit 202, a wireless communication unit 203, and a communication antenna control unit 204.

[0057] Control unit 201 executes a control program stored in storage unit 202 to control the entire device. Control unit 201 includes, for example, one or more processors such as a CPU or MPU, and executes a control program read into RAM, which serves as storage unit 202, to control the entire communication device. The processes performed by control unit 201 as described in the flowcharts below can also be implemented using hardware circuitry such as ASICs or FPGAs. ASIC stands for Application Specific Integrated Circuit. FPGA stands for Field Programmable Gate Array. The processes described in the flowcharts below can also be implemented through cooperation between hardware circuitry and processors such as CPUs or MPUs.

[0058] Storage unit 202 stores control programs executed by control unit 201, as well as various types of information, such as information about the UE to be connected and the connection strength with the base station or IAB donor 110. Storage unit 202 may include a main storage unit and an auxiliary storage unit. The main storage unit is, for example, ROM (Read-Only Memory) or RAM (Random Access Memory). The main storage unit may store or temporarily store programs and data, such as the OS (Operating System) as the basic software executed by control unit 201, and application software. The auxiliary storage unit is, for example, HDD (Hard Disk Drive) or SSD (Solid State Drive), and may store data related to application software, etc. For example, the control program stored in a non-volatile memory area is loaded into RAM (Random Access Memory) and executed by the processor constituting control unit 201. In this way, control unit 201 and storage unit 202 can be used as a so-called computer.

[0059] The wireless communication unit 203 performs cellular network communication conforming to 3GPP standards, such as 5G. Specifically, the wireless communication unit 203 performs communication control of the RAN (Radio Access Network) and upper-layer communication control, such as 5G NR (New Radio), to perform cellular network communication. Although 5G is shown as an example of cellular network communication, the invention is not limited thereto, and the control in this embodiment can also be implemented based on cellular network communication such as 5G Advanced / 6G. In this case, the wireless communication unit 203 performs cellular network communication conforming to 3GPP standards, such as 5G Advanced or 6G.

[0060] The communication antenna control unit 204 controls the antenna used for wireless communication performed in the wireless communication unit 203.

[0061] GPS communication unit 205 receives satellite signals from GPS (Global Positioning System) satellites and acquires location information, including location identifiers such as longitude / latitude, and current time. GPS communication unit 205 may have the function of measuring (positioning) the current location based on satellite signals. Instead of GPS, or in addition to GPS, any other GNSS (Global Navigation Satellite System) can be used.

[0062] GPS antenna control unit 206 controls the antenna (not shown) used for GPS communication performed by GPS communication unit 205.

[0063] Figure 2B This is a software functional block diagram of the MBSR in the embodiments described below. Although the configuration of MBSR 102 (103) will now be described, this also applies to MBSR 101.

[0064] Software function block 301 is stored in storage unit 202 and executed by control unit 201. Software function block 301 includes signal transmission unit 302, signal receiving unit 303, data storage unit 304, connection control unit 305, network configuration information management unit 306, relay request processing unit 307, and signal generation unit 308. Software function block 301 also includes GPS signal processing unit 309 and mode switching unit 310.

[0065] The signal transmission unit 302 and the signal receiving unit 303 control the wireless communication unit 203 via the control unit 201, and perform 3GPP compliant cellular network communications such as LTE and 5G with the IAB donor 110, another MBSR and UE 122.

[0066] Data storage unit 304 controls and manages storage unit 202 as an entity, and stores and maintains the software itself, information about the connection with IAB donor 110, information about UE 122, etc. Inter-node information can be collected via broadcast signals and communication packets (hereinafter referred to as BAP control packets) accompanying various control PDUs of the BAP. Information from the UE can be collected based on, for example, RRC status.

[0067] During wireless communication, the connection control unit 305 controls the communication antenna control unit 204 via the control unit 201. The connection control unit 305 generates connection control signals based on information generated by the network configuration information management unit 306 (described below). In MBSR 102 (103), upon receiving a response specifying a relay-only connection (connection in relay mode) from another communication device (MBSR 101 described below in this embodiment), the connection control unit 305 determines to connect to that other communication device.

[0068] The network configuration information management unit 306 manages the configuration information of the IAB network configured to include MBSR 102 (103). The network configuration information management unit 306 also manages the type information of the UE, IAB node, and MBSR requesting to connect to MBSR 102 (103).

[0069] The relay request processing unit 307 functions within MBSR 102 (103) (the second, fourth, and sixth embodiments described below). In the event of a radio link disconnection from the parent node, the relay request processing unit 307 performs various processes for a relay request to another MBSR (MBSR 101 described below in this embodiment). For example, the relay request processing unit 307 generates a relay request in response to the disconnection of the radio link with the parent node as a trigger. At this time, the relay request processing unit 307 can determine another MBSR (MBSR 101 described below in this embodiment) as the destination of the relay request. If broadcast signals are received from multiple other MBSRs before and after the radio link disconnection, the relay request processing unit 307 can determine one of these other MBSRs as the destination of the relay request. In this case, for example, the relay request processing unit 307 can determine the MBSR with the highest communication quality as the destination of the relay request.

[0070] The signal generation unit 308 manages and sends various signals generated by the connection control unit 305. In MBSR 102 (103), the signal generation unit 308 cooperates with the trunk request processing unit 307 to generate signals related to trunk requests (described below). A trunk request can be generated, for example, by adding the parameter "trunk request" to a spare field of an RRC SetUp Request message. A trunk request can also be generated by adding information indicating a trunk request to broadcast information (SS / PBCH block). This will be referred to below. Figure 10A and 10B Describe it.

[0071] The GPS signal processing unit 309 performs communication conforming to the GPS standard. The GPS signal processing unit 309 controls the antenna used for GPS communication performed by the GPS communication unit 205, and calculates the current position and time from the received GPS information. The GPS signal processing unit 309 outputs information in NMEA (National Marine Electronics Association)-0183 format, and performs processing to store the current position and time in the data storage unit 304 when necessary.

[0072] Mode switching unit 310 functions in MBSR 101. Mode switching unit 310 switches operating modes between normal mode and relay mode. In this embodiment, mode switching unit 310 switches from normal mode to relay mode in response to a request (request to switch to relay mode) from IAB donor 110, as described below. Alternatively, in addition to, or replacing this, mode switching unit 310 switches from normal mode to relay mode in response to a request from an MBSR whose radio link with IAB donor 110 has been disconnected.

[0073] The normal mode corresponds to the following mode: in this mode, the DU (Distributed Unit) used as the radio functional unit of MBSR 101 only allows the UE to connect to it and prohibits connections from other IAB nodes (including MBSR). That is, the normal mode corresponds to the single-hop support mode that allows connections to the UE but does not allow connections to child nodes under MBSR 101.

[0074] Relay mode refers to the following mode: in this mode, the MBSR is not connected to any UE and only performs relay to another MBSR used as a child node. Relay mode corresponds to the following mode: in this mode, multi-hop is supported and the DU used as a radio functional unit only allows the MBSR to connect to it.

[0075] Normal mode may disallow connections from MBSRs below MBSR 101, but allows connections between the UE and normal IAB nodes other than MBSRs. Relay mode may allow connections from another IAB node, including MBSRs.

[0076] The activation of the new DU (hereinafter also referred to as "new DU") in the MBSR 101 described below first involves confirming that bandwidth is available for allocation. After confirmation, a functional unit equivalent to software function block 301 is created. At this time, a new cell with a frequency different from the cell formed by the initial DU is formed. At this time, the MBSR 101 performs dual activation of the two DUs, and various methods can be used for such activation. The antenna and hardware structure for the second DU can be prepared separately, and the processor of the MBSR 101 can control the antenna and hardware structure to activate the new DU. Multiple DUs can be activated by software while sharing the antenna and hardware structure. In this case, the MBSR 101 activates multiple tasks corresponding to the software function block 301 that performs control to realize the function of the DU. The tasks activated on the MBSR 101 only need to access the antenna and hardware structure by using time-division techniques, etc., to substantially realize the function of the existing DU and the function of the new DU simultaneously.

[0077] Figure 2C This is a block diagram illustrating an example of the hardware configuration 401 of the IAB donor 110 according to this embodiment.

[0078] The hardware configuration 401 includes a control unit 402, a storage unit 403, a wireless communication unit 404, and a communication antenna control unit 405.

[0079] Control unit 402 executes a control program stored in storage unit 403 to control the entire device. Control unit 402 includes, for example, one or more processors such as a CPU or MPU, and executes the control program read into RAM, which serves as storage unit 403, to control the entire communication device. The processes performed by control unit 402 as described in the flowcharts below can also be implemented using hardware circuitry such as an ASIC or FPGA. The processes described in the flowcharts below can also be implemented through cooperation between hardware circuitry and processors such as a CPU or MPU.

[0080] Storage unit 403 stores the control program executed by control unit 402, as well as various types of information, such as cell information, connected terminal information, IAB routing information, and location information. Storage unit 403 may include a main storage unit and an auxiliary storage unit. Control unit 402 and storage unit 403 can be used as a so-called computer.

[0081] The wireless communication unit 404 performs cellular network communications such as LTE and 5G that comply with 3GPP (registered trademark) standards.

[0082] The communication antenna control unit 405 controls the antenna (not shown) used for wireless communication performed by the wireless communication unit 404.

[0083] Figure 2D This is a block diagram illustrating an example of the hardware configuration of the IAB donor 110 according to this embodiment.

[0084] The software function 501 includes a signal transmission unit 502, a signal receiving unit 503, a data storage unit 504, a connection control unit 505, a broadcast information detection unit 506, a neighboring node determination unit 507, and a mode change instruction generation unit 508.

[0085] The signal transmission unit 502 and the signal receiving unit 503 perform cellular network communication with the terminal equipment in accordance with 3GPP standards such as LTE and 5G. Control plane signals are received by the signal receiving unit 503.

[0086] In this embodiment, the signal transmission unit 502 transmits a transition instruction generated by the mode change instruction generation unit 508 (described below) to the MBSR, which is a relay candidate (described below).

[0087] In this embodiment, the signal receiving unit 503 acquires information that enables the determination of whether the peer communication device is an MBSR (i.e., an IAB node of a type relating to mobility). Such information is optional and can be, for example, information that explicitly indicates or implies that the peer communication device is an MBSR, information that explicitly indicates or implies that the peer communication device is not an MBSR, etc. In this embodiment, such information is IAB node type information, and its details will be described below.

[0088] Data storage unit 504 stores and maintains the software itself, IAB routing information, information about connected terminals, current time information, location information, movement route information, etc.

[0089] The connection control unit 505 controls the antenna for wireless communication performed by the wireless communication unit 104.

[0090] The broadcast information detection unit 506 detects broadcast information from neighboring base stations and MBSRs.

[0091] In the event of a radio link loss with the MBSR, the proximity node determination unit 507 determines whether another node that can connect to the MBSR is located nearby. An example of the determination method will be provided below in relation to the description below. Figure 3 S302 in the document is described.

[0092] The mode change instruction generation unit 508 generates a request to switch to relay mode (an instruction to change to relay mode). The request to switch to relay mode is transmitted to the MBSR, which is a relay candidate (described below). The conditions for generating the request to switch to relay mode will be described below.

[0093] <First Example: Relay Request from IAB Donor to MBSR (without UE)>

[0094] Figure 3 The illustration shows the processing flow in this embodiment (which also applies to the third and fifth embodiments described below) in which the IAB donor 110 generates an instruction to change the mode to relay mode.

[0095] IAB donor 110 determines whether the connection to the MBSR under IAB donor 110 is broken (S300). In this example, as described above, it is assumed that the connection to MBSR 103 is broken. In this case, IAB donor 110 obtains the location information of each node under it (e.g., IAB node and MBSR) (S301). IAB donor 110 can obtain the location information of each node directly from each node under it using RRC messages. The location information can be included in the Measurement Report. IAB donor 110 can obtain the location information of each node from the core network 150. Then, based on the location information, IAB donor 110 determines whether another node (here, the IAB node) or another IAB donor that can be connected to MBSR 103 is located near MBSR 103 (S302). The term "near MBSR 103" refers to the area within a predetermined distance from the location of MBSR 103, and the predetermined distance can be predefined.

[0096] If another node that can connect to MBSR 103 is found, then MBSR 103 connects via that other node (S304). On the other hand, if no other node that can connect to MBSR 103 is found, then the IAB donor 110 determines whether one or more other MBSRs that can connect to MBSR 103 are found (S303). If no other MBSRs that can connect to MBSR 103 are found, then the process ends. On the other hand, if only one other MBSR that can connect to MBSR 103 is found, then the IAB donor 110 sends a request to that other MBSR to switch to relay mode (an instruction to change to relay mode) (S307). If multiple other MBSRs that can connect to MBSR 103 are found (S305), then, for example, the following can be performed: That is, based on measurement reports previously obtained from the other MBSRs, the other MBSR with the highest communication quality with MBSR 103 is identified as a relay candidate (S306). Each of these other MBSRs can notify IAB donor 110 of the communication quality between MBSR 103 and itself using the alternative field “nonCriticalExtension”. This alternative field is specified in the measurement report message format defined in Chapter 6.2.2 of TS 38.331. For example, a field indicating communication quality, “MBSR Communication Information”, can be added to the alternative field. In this case, the fields of MBSR Communication Information may include communication status information (such as delay time).

[0097] In this case, IAB donor 110 sends a request to switch to relay mode (instruction to switch to relay mode) to another MBSR with the highest communication quality (S307).

[0098] exist Figure 3 In this case, step S306 can be omitted. Alternatively, another MBSR located closest to the detected disconnected MBSR103 can be identified as a relay candidate, or another MBSR can be identified as a relay candidate based on another criterion.

[0099] Figure 4 The illustration shows the process flow for determining the pattern of MBSR in this embodiment (which also applies to the second to fourth embodiments described below).

[0100] The MBSR connects to the network in normal mode (S401). If a mode change instruction is received from IAB donor 110 (S402), the MBSR checks the presence or absence of the UE connected to it (S403). If a connected UE is found, the MBSR activates a new DU in relay mode (S406). If no connected UE is found, the MBSR operates in relay mode (S405). If no change instruction is received in S402, the MBSR continues to operate in normal mode (S404). As a method for activating a new DU in relay mode, multiple DUs can be activated using virtualization technology. Depending on the communication performance of the MBSR, functions can be partitioned to provide services.

[0101] Figure 5 This is a sequence diagram illustrating the flow from when the IAB donor 110 detects the disconnection of MBSR 103 until MBSR 103 connects to MBSR 101, which is operating as a relay node.

[0102] MBSR 101 broadcasts that it is operational as a relay node (S501). An SSB (Synchronization Signal Block) message is used for this broadcast. However, instead of broadcasting information in S501, rsinfo can be newly defined in the nonCriticalExtension defined in SIB1 (or another SIB besides SIB1), and information indicating that MBSR 101 is operational in relay mode can be broadcast. Alternatively, MBSR 101 can provide notification of its operational status as a relay node via an F1 message or an RRC message.

[0103] MBSR 103 receives a broadcast signal from MBSR 101. However, because MBSR 103 is connected to its parent node (i.e., IAB donor 110) at this stage, MBSR 103 does not respond. Subsequently, if MBSR 103 becomes hidden behind an obstacle due to its movement, the wireless connection with IAB donor 110, which acts as its parent node, is lost. After detecting the loss of connection with MBSR 103 under IAB donor 110 (S502), IAB donor 110 transmits a connection request in relay mode to MBSR 101, which is another child node connected to it (S503). At this time, the connection request can be transmitted based on location information or other conditions that confirm MBSR 103 is in a connectable state.

[0104] In the transmission signal from IAB donor 110 to MBSR 101, the parameter "reconnection request for disconnected MBSR" is added. Figure 6 The alternative field for the RRC Reconfiguration message in the RRC protocol. Alternatively, the parameter "Reconnection request for a disconnected MBSR" can be added. Figure 7 The BAP message in the S901 is an alternate field for PDU Type, and can also transmit connection requests. BAP is an abbreviation for Backhaul Adaptation Protocol.

[0105] In this embodiment, it is assumed that MBSR 101 is not connected to the UE and operates in relay mode based on the response from IAB donor 110 (see [link]). Figure 4 (S405 in the original text). Specifically, upon receiving a request from IAB donor 110, MBSR 101 switches from the normal mode, which only supports single hops, to relay mode (S504). That is, MBSR 101 sends a response to IAB donor 110 indicating that MBSR 101 is connectable in relay mode (S504), and switches from normal mode to relay mode (S505). Then, MBSR 101 sends a broadcast signal indicating that MBSR 101 is operating in relay mode (S505A). As a means of providing notification that MBSR 101 is operating in relay mode, MBSR 101 may transmit the notification to MBSR 103 via unicast using an RRC reconfiguration message of the RRC protocol, instead of broadcasting. In this case, the message format for broadcasting the relay request may include those described below. Figure 11 The diagram shows the RRC reconfiguration message in the RRC protocol.

[0106] Since MBSR 103 has identified MBSR 101 as a connectable parent node, MBSR 103 determines to connect to MBSR 101, which serves as the parent node (S506). Then, MBSR 103 executes a random access procedure for connecting to MBSR 101 (S507), requests a connection via an RRC setup request message, and completes the connection (S508). IAB donor 110 performs backhaul (BH) path setup with MBSR 101 and MBSR 103, and establishes a BH RLC channel for data communication (S509). BH RLC is an abbreviation for Backhaul Radio Link Control. Through this series of sequences, UE 123 connected to MBSR 103 can perform data communication.

[0107] <Second Implementation Example: Relay Request from a Disconnected MBSR to Another MBSR (Without a UE)>

[0108] Figure 8A The diagram illustrates a flowchart of MBSR 103 disconnected from its parent node. After detecting the disconnection in S801, MBSR 103 broadcasts a relay request to other MBSRs (S802). Upon receiving a response or broadcast from a relayable MBSR 101 (S803), MBSR 103 attempts to connect to that relayable MBSR 101 (S804). If no other connectable MBSR is found in S803, MBSR 103 searches for another relayable MBSR.

[0109] Figure 8A Assume there exists an MBSR (MBSR 101) capable of relaying. However, as... Figure 8B As shown, responses or broadcasts may be received from multiple MBSRs ("Yes" in S803A). In this case, for example, based on the responses or broadcasts from each MBSR, the MBSR with the highest communication quality can be identified as a relay candidate (S803B). For example, the MBSR with the highest received signal strength among the received signals associated with the responses or broadcasts from each MBSR can be identified as a relay candidate (S803B).

[0110] Figure 9 This is a sequence diagram illustrating the process until a connection is established by another MBSR 101 performing a relay in response to a disconnected MBSR 103 requesting the same relay.

[0111] Furthermore, in this embodiment, similar to the first embodiment described above, it is assumed that MBSR 101 is not connected to the UE and is operable in relay mode according to the response from IAB donor 110 (see...). Figure 4 (S405 in the middle).

[0112] MBSR 101 broadcasts that it is operational as a relay node (S901). MBSR 103 receives the broadcast signal from MBSR 101. However, because MBSR 103 is connected to its parent node at this stage, MBSR 103 does not respond. Subsequently, if MBSR 103 becomes hidden behind an obstacle due to its movement, the wireless connection with the IAB donor 110, which is acting as the parent node, is lost, and MBSR 103 detects the disconnection from the parent node (S902).

[0113] MBSR 103 has identified MBSR 101 as capable of relaying from the broadcast signal from MBSR 101. Therefore, MBSR 103 transmits a message to MBSR 101 obtained by adding the parameter "relay request" to the spare field of the RRC setting request message (S903).

[0114] Alternatively, if no broadcast is received from MBSR 101 in S901, MBSR 103 may transmit broadcast information (SS / PBCH block) that additionally includes information indicating a relay request. In this case, the message format for broadcasting the relay request may include... Figure 10A The SIB1 message shown here includes parameters such as SIB1-v1700-IEs, and the parameter "Relay Request" is added as a fallback field to "Reason of NonAccess". Alternatively, the message format used to transmit the relay request may include adding... Figure 10B The parameter "Relay Request" in the "Parameters for Providing Notifications to IAB Nodes" shown is an example.

[0115] Upon receiving a relay request from MBSR 103, MBSR 101 confirms (requests) with IAB donor 110, which acts as its parent node, whether MBSR 101 can operate as a relay node (S904). IAB donor 110 sends a response to MBSR 101 indicating that MBSR 101 can operate in relay mode (S905). Upon receiving the response from IAB donor 110, MBSR 101 switches from normal mode, which only supports single hops, to relay mode (S906). MBSR 101 sends a broadcast signal indicating that MBSR 101 is operating in relay mode (S907). The means for providing notification of operation in relay mode is not limited to broadcasting, and the RRC reconfiguration message of the RRC protocol can be used to transmit the notification to MBSR 103 via unicast. In this case, the message format for broadcasting the relay request may include... Figure 11The RRC reconfiguration message of the RRC protocol shown.

[0116] Since MBSR 103 has identified MBSR 101 as a connectable parent node, MBSR 103 determines to connect to MBSR 101 as the parent node and performs a random access procedure (S908). MBSR 103 requests a connection via an RRC setup request message and completes the connection (S909). IAB donor 110 performs backhaul path setup with MBSR 101 and MBSR 103 via MBSR 101 and establishes a BH RLC channel for data communication (S910). Through this series of sequences, UE 123 connected to MBSR 103 can perform data communication.

[0117] exist Figure 9 In the first version, MBSR 101 operates in relay mode in response to a request from IAB donor 110 (S904, S905). In the second version, MBSR 101 can operate in relay mode in response to a relay request from MBSR 103 (S903).

[0118] <Third Implementation: Relay Request from IAB Donor to MBSR (with UE)>

[0119] Figure 12 This is a sequence diagram illustrating the request from IAB donor 110 to another MBSR 101 to perform a relay after the disconnection of MBSR 103 is detected.

[0120] This embodiment is based on the premise that the MBSR 101 with relay function is connected to the UE 121 below it (S1201). That is, unlike the first and second embodiments described above, this embodiment assumes that the MBSR 101 is connected to the UE 121. In this case, the MBSR 101 is activated with the new DU according to the response from the IAB donor 110 (see...). Figure 4 S406 in the above configuration is operable in relay mode. If, contrary to this assumption, MBSR 101 is not connected to UE 121, then the configuration can be the same as in the first and second embodiments described above.

[0121] MBSR 101 broadcasts that it is operable as a relay node (S1202). MBSR 103 receives the broadcast signal from MBSR 101. However, since MBSR 103 is connected to its parent node at this stage, it does not respond. Subsequently, if MBSR 103 becomes hidden behind an obstacle due to its movement, the wireless connection with IAB donor 110, which acts as the parent node, is lost. IAB donor 110 detects the loss of connection with its subordinate MBSR 103 (S1203). Then, if IAB donor 110 can confirm that MBSR 103 is in a connectable state based on MBSR 103's location information, etc., then IAB donor 110 transmits a connection request in relay mode to MBSR 101, which is another child node connected to it (S1204). In the transmission signal from IAB donor 110 to MBSR 101, the parameter "connection request for the disconnected MBSR" is added. Figure 6 The alternative field of the RRC reconfiguration message in the RRC protocol. Alternatively, the parameter "reconnection request for a disconnected MBSR" can be added. Figure 7 The spare field of the PDU type S901 in the BAP message can also transmit connection requests.

[0122] IAB donor 110 sends a response to MBSR 101 indicating that MBSR 101 can operate in relay mode (S1205). Since MBSR 101 is connected to the UE, using the same DU to simultaneously perform a relay connection with another node increases complexity. Therefore, MBSR 101 newly activates DU2 (192), which is different from DU1 (191) connected to UE 121, and uses DU2 (192) for relaying with MBSR 103 (S1206). MBSR 101 sends a broadcast signal indicating that MBSR 101 is operating in relay mode (S1207).

[0123] Since MBSR 103 has identified MBSR 101 as a connectable parent node through the reception of the aforementioned broadcast signal, MBSR 103 determines to connect to MBSR 101, which serves as the parent node, and performs a random access procedure for MBSR 101 (S1208). Afterward, MBSR 103 requests a connection via an RRC setup request message and completes the connection (S1209). IAB donor 110 performs backhaul path setup with MBSR 103 via MBSR 101's DU2 (192) and establishes a BHRLC channel for data communication (S1210).

[0124] Through this series of sequences, UE 123 connected to MBSR 103 can perform data communication.

[0125] <Fourth Embodiment: Relay Request from a Disconnected MBSR to Another MBSR (with UE)>

[0126] Figure 13 This is a sequence diagram illustrating the process of establishing a connection until a disconnected MBSR 103 requests another MBSR 101 to perform relay. However, this embodiment is based on the premise that the relaying MBSR 101 is connected to UE 121 and UE 121 is connected to DU1 (191), which serves as a radio functional unit of MBSR 101, and data communication continues (S1301). That is, unlike the first and second embodiments described above, this embodiment assumes that MBSR 101 is connected to UE 121. In this case, MBSR 101 activates a new DU in response to a response from IAB donor 110 (see...). Figure 4 S406 in the above configuration is operable in relay mode. If, contrary to this assumption, MBSR 101 is not connected to UE 121, then the configuration can be the same as in the first and second embodiments described above.

[0127] MBSR 101 broadcasts that it is operable as a relay node (S1302). MBSR 103 receives the broadcast signal from MBSR 101. However, because MBSR 103 is connected to the parent node at this stage, MBSR 103 does not respond. Subsequently, if MBSR 103 becomes hidden behind an obstacle due to its movement, the wireless connection with the IAB donor 110, which is acting as the parent node, is lost, and MBSR 103 detects the disconnection from the parent node (S1303).

[0128] MBSR 103 has identified MBSR 101 as capable of relaying based on the broadcast signal from MBSR 101. Therefore, MBSR 103 transmits a message to MBSR 101 obtained by adding the parameter "Relay Request" to the spare field of the RRC setting request message (S1304). Alternatively, as in the third embodiment, if no broadcast is received in S1302, MBSR 103 may transmit relay capability information (SS / PBCH block) that additionally includes information indicating a relay request.

[0129] Upon receiving a relay request from MBSR 103, MBSR 101 confirms with IAB donor 110, which acts as the parent node, whether MBSR 101 can operate as a relay node (S1305). IAB donor 110 sends a response to MBSR 101 indicating that MBSR 101 can operate in relay mode (S1306).

[0130] When MBSR 101 is operating in "relay mode", the complexity of performing a connection with another node via DU1 (191) connected to UE 121 increases. Therefore, a new DU2 (192), different from DU1 (191) connected to UE 121, is newly activated and used for relaying with MBSR 103 (S1307).

[0131] MBSR 101 transmits a broadcast signal indicating that MBSR 101 is operating in relay mode (S1308). The means for providing notification of operation in relay mode is not limited to broadcasting, and an RRC reconfiguration message can be used to transmit the notification to MBSR 103.

[0132] Since MBSR 103 has identified MBSR 101 as a connectable parent node, MBSR 103 determines to connect to MBSR 101 as the parent node and performs a random access procedure for MBSR 101 (S1309). Afterwards, MBSR 103 requests and completes the connection via an RRC setup request message, etc. (S1310). IAB donor 110 performs backhaul path setup with MBSR 103 via DU2 (192) of MBSR 101 and establishes a BH RLC channel for data communication (S1311). Through this series of sequences, UE 123 connected to MBSR 103 can perform data communication.

[0133] <Fifth Implementation: Relay Request from IAB Donor to Another MBSR (with UE)>

[0134] Figure 14 The diagram illustrates the processing flow for determining the mode of the MBSR in this embodiment (which also applies to the sixth embodiment described below). The MBSR connects to the network as an MBSR in normal mode (S1401). If a mode change instruction is received from the IAB donor (S1402), the MBSR checks the presence or absence of the UE connected to it (S1403). If a connected UE is found, the MBSR releases the connection with the connected UE and then operates in relay mode (S1406). If no connected UE is found, the MBSR operates in relay mode (S1405). If no change instruction is received in S1402, the MBSR continues to operate in normal mode (S1404).

[0135] Figure 15 This is a sequence diagram illustrating the process until the IAB donor requests another MBSR101 to perform relay and establish a connection after detecting the disconnection of MBSR103.

[0136] Unlike the first and second embodiments described above, this embodiment assumes that MBSR 101 is connected to UE 121. In this case, MBSR 101 is operable in relay mode after releasing the connection with the connected UE based on the response from IAB donor 110 (see...). Figure 14 (S1406 in the above). If, contrary to this assumption, MBSR 101 is not connected to UE 121, then the configuration can be the same as in the first and second embodiments described above.

[0137] Specifically, refer to Figure 15 In this embodiment, another MBSR has a UE 121 under it, and the UE 121 is connected to the MBSR 101 and continues data communication (S1501).

[0138] MBSR 101 broadcasts that it is operable as a relay node (S1502). MBSR 103 receives the broadcast signal from MBSR 101. However, since MBSR 103 is connected to its parent node at this stage, it does not respond. Subsequently, if MBSR 103 becomes hidden behind an obstacle due to its movement, the wireless connection with IAB donor 110, which acts as its parent node, is lost. After detecting the loss of connection with MBSR 103 under IAB donor 110 (S1503), IAB donor 110 transmits a connection request in relay mode to MBSR 101, which is another child node connected to it (S1504). At this time, the connection request can be transmitted under the condition that MBSR 103 is in a connectable state based on its location information, etc. In the transmission signal from IAB donor 110 to MBSR 101, the parameter "connection request for the disconnected MBSR" is added. Figure 6 The alternative field of the RRC reconfiguration message in the RRC protocol. Alternatively, the parameter "reconnection request for a disconnected MBSR" can be added. Figure 7 The spare field of the PDU type S901 in the BAP message can also transmit connection requests.

[0139] IAB donor 110 sends a response to MBSR 101 indicating that MBSR 101 can operate in relay mode (S1505). If MBSR 101 switches from normal mode to relay mode and operates in relay mode, maintaining the connection with the UE while simultaneously establishing a connection with another node increases complexity. Therefore, MBSR 101 releases the connection with UE 121 using an RRC Release message (or provides notification of another connectable IAB node) and specifically operates for relaying with MBSR 103 (S1506, S1507).

[0140] MBSR 101 transmits a broadcast signal instructing MBSR 101 to operate in relay mode (S1508). Since MBSR 103 has identified MBSR 101 as a connectable parent node, MBSR 103 determines to connect to MBSR 101, which serves as its parent node. MBSR 103 then performs a random access procedure for connecting to MBSR 101 (S1509), requests a connection via an RRC setup request message, and completes the connection (S1510). IAB donor 110 performs backhaul path setup with MBSR 101 and MBSR 103 via MBSR 101 and establishes a BH RLC channel for data communication (S1511). Through this series of sequences, UE 123 connected to MBSR 103 can perform data communication.

[0141] <Sixth Embodiment: Relay Request from a Disconnected MBSR to Another MBSR (with UE)>

[0142] Figure 16 This is a sequence diagram illustrating the process until a connection is established by another MBSR 101 performing a relay in response to a disconnected MBSR 103 requesting the same relay.

[0143] Unlike the first and second embodiments described above, this embodiment assumes that MBSR 101 is connected to UE 121. In this case, MBSR 101 is operable in relay mode after releasing the connection with the connected UE based on the response from IAB donor 110 (see...). Figure 14 (S1406 in the above). If, contrary to this assumption, MBSR 101 is not connected to UE 121, then the configuration can be the same as in the first and second embodiments described above.

[0144] Specifically, refer to Figure 16 In this embodiment, another MBSR has a UE 121 under it, and the UE 121 is connected to the MBSR 101 and continues data communication (S1601).

[0145] MBSR 101 broadcasts that it is operable as a relay node (S1602). MBSR 103 receives the broadcast signal from MBSR 101. However, because MBSR 103 is connected to the parent node at this stage, MBSR 103 does not respond. Subsequently, if MBSR 103 becomes hidden behind an obstacle due to its movement, the wireless connection with the IAB donor 110, which is acting as the parent node, is lost, and MBSR 103 detects the disconnection from the parent node (S1603).

[0146] MBSR 103 has identified MBSR 101 as capable of relaying from the broadcast signal from MBSR 101. Therefore, MBSR 103 transmits a message to MBSR 101 obtained by adding the parameter "Relay Request" to the spare field of the RRC setup request message (S1604). Alternatively, as in the third embodiment, if no broadcast is received in S1602 (indicating that MBSR 101 is operable as a relay node), then MBSR 103 may transmit relay capability broadcast information (SS / PBCH block) that additionally includes information indicating the relay request.

[0147] Upon receiving a relay request from MBSR 103, MBSR 101 confirms with IAB donor 110 whether MBSR 101 can operate as a relay node (S1605). IAB donor 110 sends a response to MBSR 101 indicating that MBSR 101 can operate in relay mode (S1606). If MBSR 101 operates in "relay mode," maintaining a connection with the UE while simultaneously establishing a connection with another node increases complexity. Therefore, MBSR 101 releases its connection with UE 121 and is used for relaying with MBSR 103 (S1607, S1608).

[0148] MBSR 101 transmits a broadcast signal indicating that it is operating in relay mode (S1609). The means of providing notification of operation in relay mode is not limited to broadcasting, and an RRC reconfiguration message can be used to transmit the notification to MBSR 103. Since MBSR 103 has identified MBSR 101 as a connectable parent node, MBSR 103 determines to connect to MBSR 101 as its parent node and performs a random access procedure to connect to MBSR 101 (S1610). Thereafter, MBSR 103 requests a connection via an RRC setup request message and completes the connection (S1611). IAB donor 110 performs backhaul (BH) path setup with MBSR 103 via MBSR 101's DU2 (192) and establishes a BH RLC channel for data communication (S1612).

[0149] Through this series of sequences, UE 123 connected to MBSR 103 can perform data communication.

[0150] <Other Embodiments>

[0151] In the above embodiments, an example is illustrated where the MBSR begins operation in relay mode after receiving a relay request. However, the MBSR can be configured to reject relay requests when necessary. Upon receiving a relay request, the MBSR can determine whether to reject the request based on its resource congestion status, etc. After determining to reject the relay request, the MBSR notifies the source device from which the relay request was transmitted of a message indicating that the relay request has been rejected. In this case, after receiving the message indicating rejection, the source device can simply transmit the relay request to another candidate device. For example, in situations such as when frequency resources available to the MBSR are already congested due to existing communication, or when the number of UEs already connected to the MBSR is greater than or equal to a predetermined number, the MBSR can reject the relay request upon receiving it. This process makes it possible to prevent adverse effects on existing communication.

[0152] This embodiment can also be implemented through the following process: in this process, a program for implementing one or more functions of each of the above embodiments is supplied to the system or device via a network or storage medium, and one or more processors of the computer of the system or device read and execute the program. This embodiment can also be implemented by circuitry (e.g., ASIC or FPGA) that implements one or more functions.

[0153] Although embodiments have been described in detail, the present invention is not limited to any particular embodiment, and various modifications and changes can be made within the scope defined in the claims. Furthermore, all or more of the constituent elements of the above embodiments can be combined.

[0154] The following appendix further discloses information regarding the above embodiments.

[0155] [Appendix 1]

[0156] A communication device having MBSR (Mobile Base Station Relay) operation function, wherein

[0157] The communication device is operable in a first mode in which only one other communication device is connected to the DU (Distributed Unit) of the communication device, the other communication device having MBSR operation function, and the first mode is a mode in which communication between the other communication device and the IAB (Integrated Access and Backhaul) donor is relayed.

[0158] [Appendix 2]

[0159] The communication device according to Appendix 1 includes a mode switching component for switching an operating mode between a first mode and a second mode, wherein in the second mode only the UE (User Equipment) is connected to the DU of the communication device.

[0160] [Appendix 3]

[0161] According to the communication device described in Appendix 1 or 2, when the communication device is operating in the first mode, the communication device only allows connections from the UE and the other MBSR.

[0162] [Appendix 4]

[0163] According to the communication device described in Appendix 2, wherein when the communication device switches from the second mode to the first mode while connected to the UE, the communication device activates a new DU.

[0164] [Appendix 5]

[0165] According to the communication device described in Appendix 2 or 4, the mode switching component switches from the second mode to the first mode in response to a relay request from the IAB donor or from the other communication device.

[0166] [Appendix 6]

[0167] The communication device according to any one of Appendices 1 to 5 includes a transmission component for transmitting a notification to the IAB donor or the other communication device, the notification indicating that the communication device is operable in the first mode or is operating in the first mode.

[0168] [Appendix 7]

[0169] According to any one of the communication devices described in Appendices 1 to 6, the transmission component uses SSB (Synchronization Signal Block) messages or RRC messages.

[0170] [Appendix 8]

[0171] A communication device having MBSR (Mobile Base Station Relay) operation function, wherein

[0172] In response to a relay request from an IAB (Integrated Access and Backhaul) donor, the communication device performs relay to another communication device to allow the other communication device to communicate with the IAB donor via the other communication device, the other communication device having MBSR operation capabilities.

[0173] [Appendix 9]

[0174] According to the communication apparatus described in Appendix 8, the communication apparatus changes the relay method for the other communication apparatus based on whether the communication apparatus is connected to the UE (User Equipment) when the relay request is received.

[0175] [Appendix 10]

[0176] According to the communication device described in Appendix 9, when the communication device is connected to the UE when the relay request is received, in response to the relay request, the communication device activates a new DU (Distribution Unit) and performs relay to the other communication device by using the activated new DU.

[0177] [Appendix 11]

[0178] According to the communication device described in Appendix 9 or 10, wherein, when the communication device is connected to the UE when the relay request is received, in response to the relay request, the communication device performs relay to the other communication device after releasing the connection with the UE connected to the communication device.

[0179] This invention is not limited to the embodiments described above, and can be changed and modified in various ways without departing from the spirit and scope of the invention. Therefore, the following claims are made to inform the public of the scope of the invention.

[0180] This application is based on and claims the benefit of priority to Japanese Patent Application No. 2023-216606, filed on December 22, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0181] Reference Symbol List

[0182] 100 Communication System

[0183] 101 MBSR

[0184] 102 MBSR

[0185] 103 MBSR

[0186] 110 IAB donor (main base station)

[0187] 111 vehicles

[0188] 112 vehicles

[0189] 113 vehicles

[0190] 130 Obstacles

[0191] 131 Obstacles

[0192] 140 wired links

[0193] 141 Wireless backhaul link

[0194] 142 Wireless Backhaul Link

[0195] 150-core network

[0196] 201 Control Unit

[0197] 202 storage units

[0198] 203 Wireless Communication Unit

[0199] 204 Communication Antenna Control Unit

[0200] 205 GPS communication unit

[0201] 206 GPS Antenna Control Unit

[0202] 302 Signal Transmission Unit (Example of a Transmission Component)

[0203] 303 Signal Receiving Unit

[0204] 304 Data Storage Unit

[0205] 305 Connection Control Unit

[0206] 306 Network Configuration Information Management Unit

[0207] 307 Relay Request Processing Unit

[0208] 308 Signal Generation Unit

[0209] 309 GPS Signal Processing Unit

[0210] 310 Mode Switching Unit (Example of a Mode Switching Component)

[0211] 402 Control Unit

[0212] 403 storage unit

[0213] 404 Wireless Communication Unit

[0214] 405 Communication Antenna Control Unit

[0215] 502 Signal Transmission Unit

[0216] 503 Signal Receiving Unit

[0217] 504 Data Storage Unit

[0218] 505 Connection Control Unit

[0219] 506 Broadcast Information Detection Unit

[0220] 507 Neighbor Node Determination Unit

[0221] 508 Mode Change Instruction Generation Unit.

Claims

1. A communication device, wherein the communication device has MBSR (Mobile Base Station Relay) operation function, wherein The communication device is operable in a first mode in which only one other communication device is connected to the DU (Distributed Unit) of the communication device, the other communication device having MBSR operation function, and the first mode is a mode in which communication between the other communication device and the IAB (Integrated Access and Backhaul) donor is relayed.

2. The communication device according to claim 1, comprising a mode switching component, the mode switching component being used to switch an operating mode between a first mode and a second mode, wherein in the second mode only a UE (User Equipment) is connected to the DU of the communication device.

3. The communication device according to claim 1, wherein when the communication device operates in the first mode, the communication device only allows connections from the UE and the other MBSR.

4. The communication device according to claim 2, wherein when the communication device switches from the second mode to the first mode while connected to the UE, the communication device activates a new DU.

5. The communication device of claim 2, wherein the mode switching component switches from the second mode to the first mode in response to a relay request from the IAB donor or from the other communication device.

6. The communication apparatus according to any one of claims 1 to 5, comprising a transmission component for transmitting a notification to the IAB donor or the other communication apparatus, the notification indicating that the communication apparatus is operable in the first mode or is operating in the first mode.

7. The communication apparatus of claim 6, wherein the transmitting component uses an SSB (Synchronization Signal Block) message or an RRC message.

8. A communication device, wherein the communication device has MBSR (Mobile Base Station Relay) operation function, wherein In response to a relay request from an IAB (Integrated Access and Backhaul) donor or from another communication device, the communication device performs a relay to the other communication device to allow the other communication device to communicate with the IAB donor via the other communication device, the other communication device having MBSR operation capabilities.

9. The communication apparatus of claim 8, wherein the communication apparatus changes the relay method for the other communication apparatus based on whether the communication apparatus is connected to a UE (User Equipment) when the relay request is received.

10. The communication device according to claim 9, wherein, When the relay request is received, if the communication device is connected to the UE, in response to the relay request, the communication device activates a new DU (Distribution Unit) and performs relay to the other communication device by using the activated new DU.

11. The communication device according to claim 9, wherein, If the communication device is connected to the UE when the relay request is received, in response to the relay request, the communication device performs relay to the other communication device after releasing the connection with the UE connected to the communication device.

12. A control method for a communication device, the communication device having MBSR (Mobile Base Station Relay) operation function, the control method comprising: The first mode is formed in which only one other communication device is connected to the DU (Distributed Unit) of the communication device, the other communication device having MBSR operation function, and the first mode is a mode in which communication between the other communication device and the IAB (Integrated Access and Backhaul) donor is relayed.

13. A program for causing a computer of a communication device having MBSR (Mobile Base Station Relay) operation capabilities to execute: The first mode is formed in which only one other communication device is connected to the DU (Distributed Unit) of the communication device, the other communication device having MBSR operation function, and the first mode is a mode in which communication between the other communication device and the IAB (Integrated Access and Backhaul) donor is relayed.

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