Communication device, control method, and program

Abstract

To provide a mechanism that can select a connection destination of a communication device according to the connection continuity of MBSRs.SOLUTION: Disclosed is a communication device constituting a backhaul network, the communication device having generation means that generates connection continuity information representing connection continuity related to a connection link of one or more high-order connected mobile base station relays (MBSRs), and transmission means that transmits the connection continuity information to another communication device.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] The Third Generation Partnership Project (3GPP (registered trademark)) has formulated cellular communication standards. In the cellular communication standards of 3GPP (hereinafter referred to as "3GPP standards"), standardization of Integrated Access and Backhaul (IAB), which integrates access lines and backhaul lines, is underway.

[0003] In an IAB network, radio resources used for access lines between a base station (gNB) and user equipment (UE) are also used for backhaul lines. For example, in an IAB network, radio resources in the millimeter wave band, such as the 28 GHz band, are used (Patent Document 1).

[0004] IAB technology allows relay devices (IAB nodes) to relay communications between base station devices (IAB donors) and terminal devices via wireless lines, enabling area coverage to be expanded more cheaply than using wired lines such as optical fiber.

[0005] Typically, network topology formation in an IAB is achieved by an IAB node establishing a connection with an IAB donor or another IAB node that has the best received signal strength.

[0006] Currently, studies are being conducted to form a network topology suitable for use cases such as even lower latency, high-speed, and large-capacity communications. For example, a technology has been proposed that forms an appropriate communication link according to the usage situation by notifying lower-level IAB nodes of information regarding wireless link route settings based on the results of wireless link measurement in broadcast signals and downlink reference signals (Patent Document 2).

[0007] 3GPP has been working on specifications for fixed base stations (IAB nodes that do not move) up until Release 17, which is the standardization phase. Furthermore, Release 18 proposes a new use case, Vehicle Mounted Relay, and is developing architecture and protocol specifications for IAB nodes that move, known as Mobile IAB or Mobile BaseStation Relay (MBSR). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Table 2019-534625 [Patent Document 2] Patent No. 7170727 Summary of the Invention [Problem to be solved by the invention]

[0009] If a UE or MBSR connects to another MBSR, and the IAB donor is reached via multiple MBSRs, there is a high risk of the connection being cut off because the MBSRs are mobile.

[0010] 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 more stable communication in IAB. [Means for solving the problem]

[0011] A communication device according to one aspect of the present invention is a communication device that constitutes a backhaul network, a generating means for generating connection continuity information representing connection continuity related to connection links of one or more MBSRs (Mobile Base Station Relays) connected to a higher level; The communication device is characterized by comprising a transmitting means for transmitting the connection continuity information to another communication device. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a mechanism that enables more stable communication in IAB. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an IAB network. [Figure 2] FIG. 1 is a hardware functional block diagram of MBSR. [Figure 3] 1 is a software functional block diagram of MBSR. [Figure 4] FIG. 10 is a sequence diagram showing an example of connection processing in a UE and an MBSR (first embodiment); [Figure 5] 10 is a flowchart illustrating an example of a process for determining a connection destination in a UE and an MBSR. [Figure 6] 10 is a flowchart illustrating an example of calculation of the MBSR hop number and transmission processing in MBSR. [Figure 7] FIG. 10 is a sequence diagram showing an example of connection processing in a UE and an MBSR (second embodiment); DETAILED DESCRIPTION OF THE INVENTION

[0014] Each embodiment will be described in detail below with reference to the accompanying drawings.

[0015] [Embodiment 1] FIG. 1 illustrates an example of the configuration of an IAB network according to an embodiment of the present disclosure.

[0016] 1, the following situation is assumed: In the IAB network 100, there is a donor 101 that provides a connection to the CN 130, and the UE 110 or the MBSR 107 is attempting to connect to the IAB network 100. The UE 110 or the MBSR 107 wakes up from a sleep state to start a connection process with the IAB donor or one of the nodes 101 to 106 that make up the IAB network 100.

[0017] Here, CN stands for Core Network, and is responsible for various processes such as authentication of the terminal UE 110 and slice usage registration.

[0018] The UE 110 is a mobile terminal used by a bus passenger or a pedestrian. The MBSRs 104 to 107 are communication devices mounted on the bus and function as IAB nodes that move along with the movement of the bus.

[0019] In the IAB network 100, fixed IAB nodes 102 and 103, which do not involve movement, are connected to an IAB donor 101, and mobile MBSRs 104-106 are connected below the IAB 102. Because an MBSR is a type of IAB node, for convenience of explanation, the MBSRs 104-106 may be referred to as IAB nodes 104-106 or mIAB nodes 104-106. mIAB is an abbreviation for mobile IAB. Each IAB donor and IAB node 101-106, including the MBSR, periodically transmits a Master Information Block (MIB) and a System Information Block (SIB) as broadcast signals. Based on the results of analyzing the broadcast information from the IAB donor 101 and the IAB nodes 101-106, including the MBSR, the UE 110 or the MBSR 107 determines that the received radio wave strength of the MBSRs 104-106 is above a predetermined threshold and that they are suitable connection candidates. For example, assume that the following determination is made in UE 110 or MBSR 107: That is, the received signal strength from MBSR 106 is the highest, followed by MBSR 105 and MBSR 104. Also, MBSR 106 is three hops away from IAB node 102, while MBSR 105 is two hops away and MBSR 104 is one hop away. Here, the following terms are used for the number of hops: That is, the number of hops from IAB donor 101 via IAB nodes including MBSR is simply referred to as the number of hops, and the number of hops from IAB donor 101 that only passes through MBSR is distinguished from the MBSR hop count.

[0020] Here, information indicating the stability of communication in the network (backhaul) between the MBSR and the IAB donor is called connection continuity information. The connection continuity information may be, for example, the MBSR hop count. As described above, since MBSR involves movement, the greater the MBSR hop count, the higher the possibility of communication being interrupted. Therefore, the MBSR hop count indicates the stability of communication. The MBSR hop count is broadcast as connection continuity information in the broadcast information of the SIB transmitted by each MBSR 104 to 106. Here, the connection continuity information may be broadcast by the MIB or may be included in an SSB (Synchronization Signal Block). Furthermore, the hop count may be broadcast in addition to the MBSR hop count. Furthermore, the connection continuity information may be mobility information. The mobility information may include status information indicating whether the own station is moving or stationary, and location information indicating the moving speed and current location.

[0021] MBSR 106 has the largest number of MBSR hops, and therefore has a higher risk of disconnection due to movement of the MBSRs 104 and 105 connected to it at higher levels, in addition to its own movement, than the other MBSRs 104 and 105. MBSR 105 also has a 2-hop MBSR count, making it the second most likely to be disconnected after MBSR 106. Therefore, UE 110 or MBSR 107 selects MBSR 104, which has a received signal strength equal to or greater than a predetermined threshold and the smallest number of MBSR hops, as the connection destination, and executes RRC (Radio Resource Control) connection processing.

[0022] In this way, by considering the number of MBSR hops in addition to the received signal strength as a condition for determining the connection destination, it is possible to select the MBSR 104, which has the lowest risk of connection interruption among the MBSRs 104 to 106 that involve movement, as the connection destination.

[0023] In the above, the conditions were explained where the communication nodes with received radio wave intensity above the threshold do not include the IAB nodes 102 and 103. However, if the IAB nodes 102 and 103 are included and do not involve movement, the IAB nodes 102 and 103 may be preferentially selected as connection destinations because they have a lower risk of disconnection than the MBSRs 104 to 106.

[0024] In this embodiment, it is assumed that the MBSRs 104 to 107 are mounted on buses, but they may also be IAB nodes mounted on other moving objects such as vehicles, aircraft, ships, or people.

[0025] FIG. 2 is a block diagram showing an example of the hardware configuration of the MBSRs 104 to 107 in this embodiment.

[0026] The MBSRs 104 to 107 are configured from the following hardware: a control unit 201, a storage unit 202, a wireless communication unit 203, an antenna control unit 204, an antenna 205, a GPS communication unit 206, a GPS antenna control unit 207, a GPS antenna 208, and an acceleration sensor 209.

[0027] The control unit 201 includes one or more processors such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The control unit 201 may also include an FPGA (Field Programmable Gate Array), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), or the like. The control unit 201 controls the entire device by, for example, executing a control program stored in the storage unit 202.

[0028] The storage unit 202 includes one or more storage devices (memories), such as a RAM (random access memory), a ROM (read only memory), a HDD (hard disk drive), and an SSD (solid state drive). The storage unit 202 is configured to store various programs (e.g., control programs) executed by the control unit 201 and various information used in processing by the control unit 201. The various information may be, for example, connection continuity information such as the number of MBSR hops and mobility information in the MBSRs 104-106, and received radio wave intensity of other IAB donors and IAB nodes 101-106 including the MBSR.

[0029] The received signal strength may include, for example, a received signal strength indicator (RSSI) and reference signal received quality (RSRQ). RSSI is an abbreviation for Received Signal Strength Indicator. RSRQ is an abbreviation for Reference Signal Received Quality. The received signal strength may also include reference signal received power (RSRP) and the like. In addition to the received signal strength, various information may also include reception quality information, such as modulation and coding scheme (MCS), signal-to-noise ratio (SNR), and communication speed. MCS is an abbreviation for Modulation and Coding Scheme, and SNR is an abbreviation for Signal to Noise Ratio.

[0030] The wireless communication unit 203 performs processing related to wireless communication (cellular communication) that complies with 3GPP standards such as the LTE (Long Term Evolution) standard or the 5G (5th Generation) standard. However, it is also applicable to standards other than 5G (for example, 5G Advanced and 6G). The wireless communication unit 203 includes circuits for communication processing, such as a baseband chip and an RF (radio frequency) chip.

[0031] The antenna control unit 204 controls the antenna 205 used for wireless communication performed by the wireless communication unit 203. The antenna control unit 204 is also capable of measuring the strength of the received radio wave based on the signal received by the antenna 205.

[0032] The received signal strength may be measured using, for example, SSBs periodically transmitted (broadcast) from the IAB donors and nodes 101 to 106 in the MBSR 107. The SSBs are synchronization signal / broadcast channel blocks (SS / PBCH blocks). The synchronization signal / broadcast channel blocks are composed of synchronization signals (SS) and physical broadcast channels (PHCH). The SSBs are periodically transmitted from the base station mainly for the UE to detect the cell ID and reception timing when starting communication. In NR, the SSBs are also used to measure the reception quality of each cell. The PBCH includes the MIB.

[0033] The antenna control unit 204 controls the antenna 205 used for wireless communication performed by the wireless communication unit 203. The antenna control unit 204 is also capable of measuring communication quality information.

[0034] The GPS communication unit 206 receives signals from GPS (Global Positioning System) satellites to acquire current location information including location identification information such as longitude and latitude information used to generate mobility information, and current time information. Note that other satellite positioning systems such as GNSS (Global Navigation Satellite System) may be used instead of GPS.

[0035] The GPS antenna control unit 207 controls the GPS antenna 208 in the GPS communication unit 206 .

[0036] The acceleration sensor 209 measures the moving speed of the local station, which is used to generate mobility information. The moving speed measured by the acceleration sensor 209 is acquired by the control unit 201 and stored in the storage unit 202. Note that a speed sensor may be used instead of or in addition to the acceleration sensor 209. In this case, a speed sensor installed for another purpose (e.g., automatic braking control) in a vehicle such as a bus on which an MBSR is installed may be used.

[0037] Here, the UE 110 may also be realized by a similar hardware configuration or by a hardware configuration in which some of the functions are common.

[0038] FIG. 3 is a block diagram showing an example of the software functional configuration of the MBSRs 104 to 107.

[0039] The MBSRs 104 to 107 include a signal transmitting unit 301, a signal receiving unit 302, a data storage unit 303, a connection control unit 304, a connection destination determining unit 305, a hop count calculating unit 306, a movement information generating unit 307, and a GPS control unit 308. The functions of each block shown in FIG. 3 can be realized by the control unit 201 executing a control program stored in the storage unit 202.

[0040] The signal transmitting unit 301 and the signal receiving unit 302 control the wireless communication unit 203 to transmit and receive wireless signals between the IAB donor or other nodes (e.g., MBSRs 104 to 107) and the UE 110. The signal transmitting unit 301 and the signal receiving unit 302 transmit and receive wireless signals that comply with a 3GPP standard such as the LTE standard or the 5G standard.

[0041] The signal receiving unit 302 receives broadcast signals from the IAB donor or other nodes (e.g., the IAB donor 101, the IAB nodes 101 and 102, and the MBSRs 104 to 106). The signal receiving unit 302 also controls the antenna control unit 204 during wireless communication. The signal receiving unit 302 acquires received radio wave strength from the antenna control unit 204 and sends the acquired received radio wave strength to the data storage unit 303.

[0042] The data storage unit 303 stores various programs and various data (various information) in the storage unit 202 to hold them.

[0043] The connection control unit 304 performs processing related to the connection of the IAB network, such as transmitting and receiving Radio Resource Control (RRC) messages between the IAB donor or other nodes (e.g., MBSRs 104 and 107). RRC stands for Radio Resource Control. The connection control unit 304 also performs processing related to the connection with the UE 110 and the connection with the CN 130.

[0044] The connection destination determination unit 305 acquires the received signal strength of the IAB donor or other nodes (e.g., IAB donor 101, IAB nodes 101 and 102, MBSRs 104 to 106) stored in the data storage unit 303. The connection destination determination unit 305 also acquires connection continuity information from the broadcast information received by the signal receiving unit 302. Furthermore, the connection destination determination unit 305 determines the connection destination from the received signal strength and the connection continuity information. In this embodiment, the UE 110 or the MBSR 107 determines the MBSR 104 as the connection destination.

[0045] The hop count calculation unit 306 calculates the MBSR hop count for the local station from the broadcast information received by the signal reception unit 302, and includes the calculated hop count in a broadcast signal as connection continuity information, which is then transmitted from the signal transmission unit 301.

[0046] The movement information generation unit 307 acquires the movement speed measured by the acceleration sensor 209 from the data storage unit 303 and generates mobility information. The movement information generation unit 307 also generates mobility information from position information and time information from the GPS control unit. The movement information generation unit 307 includes the generated mobility information in a notification signal as connection continuity information and transmits the notification signal from the signal transmission unit 301.

[0047] The GPS control unit 308 performs communication in accordance with the GPS standard. The GPS control unit 308 also controls the antenna for GPS communication, calculates the current position and time from the received GPS information, and outputs information in a format such as NMEA (National Marine Electronics Association)-0183, and stores the current position and time in the data storage unit 303 as necessary.

[0048] Based on the current location acquired by the GPS control unit 308, the MBSRs 104 to 107 determine whether they are located inside or outside the permitted area in which they can operate as an IAB node.

[0049] The UE 110 may also be realized by a software configuration similar to that of the MBSRs 104 to 107 or with a part of the functional blocks in common.

[0050] Fig. 4 is a sequence diagram showing an example of connection between the UE 110 and the MBSR 107 according to this embodiment. In Fig. 4, it is assumed that the received radio wave intensity of the broadcast signals received by the UE 110 and the MBSR 107 from the IAB donor and the IAB nodes 101 to 103 is lower than a predetermined threshold.

[0051] In S400 to S402, the MBSRs 104 to 106 broadcast the MBSR hop count by including it in the SIB 1. The MBSR hop counts that the MBSRs 104 to 106 include in their SIB 1 are 1 for the MBSR 104, 2 for the MBSR 105, and 3 for the MBSR 106. The MBSR hop count for the MBSR 104 is 1, which means that among the MBSRs 104 to 106, the risk of connection being cut off is the lowest.

[0052] In S403, the UE 110 and the MBSR 107 receive the broadcast signals and measure the received radio wave intensity based on the broadcast signals from the MBSRs 104 to 106.

[0053] At S404, the UE 110 and the MBSR 107 wake up from a sleep state to connect to the mobile network.

[0054] In S405, the UE 110 and the MBSR 107 determine whether the received signal strength of the MBSRs 104 to 106 is equal to or greater than a threshold. The UE 110 and the MBSR 107 also determine which MBSR 104 to 106 to connect to based on the number of MBSR hops from the MBSRs 104 to 106. The UE 110 and the MBSR 107 determine the MBSR 104 with the received signal strength equal to or greater than the threshold and the smallest number of MBSR hops as the connection destination.

[0055] In S406, the UE 110 and the MBSR 107 transmit a preample, which is a randomly selected fixed pattern, to the MBSR 104 as a RACH (Random Access Channel) preample message.

[0056] At S407, the MBSR 104 receives the RACH preample message.

[0057] In S408, the MBSR 104 transmits a RACH response message to the UE 110 and the MBSR 107, notifying the UE 110 that it has received the RACH preample message and including transmission timing information and bandwidth allocation information.

[0058] At S409, the UE 110 and the MBSR 107 receive the RACH response message.

[0059] In S410, in accordance with the transmission timing and bandwidth allocation information of the RACH response message received in S409, the UE 110 and the MBSR 107 transmit an RRC connection request to the MBSR 104. The RRC connection request is an RRC connection request message.

[0060] In S411, the MBSR 104 receives an RRC connection request message.

[0061] In step S412, the MBSR 104 responds to the RRC connection request by transmitting control information for the RRC connection as an RRC connection setup message.

[0062] In S413, the UE 110 and the MBSR 107 receive the RRC connection setup message, thereby completing the RRC link connection.

[0063] In S414, the MBSR 107 transmits an RRC Setup Complite message including information that the local station is an MBSR, in order to indicate that a connection has been established as an IAB node.

[0064] In S415, the MBSR 104 receives the RRC Setup Complite message and identifies the MBSR 107 as an MBSR. In the case of the UE 110, the RRC Setup Complite message is not transmitted or received in S414 and S415.

[0065] In S416 and S417, an RRC link is established, and the UE 110 and MBSR 107 start data communication with the CN 130 via the MBSR 104 and the IAB donor 101. In addition, the MBSR 107 starts transmitting a broadcast signal including connection continuity information with the MBSR hop count set to 2.

[0066] FIG. 5 is a flowchart showing an example of a connection destination determination process in the UE 110 and the MBSR 107 according to this embodiment.

[0067] Here, a description will be given of a method for determining a connection destination in UE 110 and MBSR 107 in S405. Note that the connection destination determination process is executed in connection destination determination section 305.

[0068] In S500, the UE 110 and the MBSR 107 receive the MBSR hop count as connection continuity information from the broadcast signals from the IAB donor and the IAB nodes 101 to 106. In addition, the UE 110 and the MBSR 107 measure the received radio wave intensity from the broadcast signals from the IAB donor and the IAB nodes 101 to 106.

[0069] In S501, the UE 110 and the MBSR 107 determine whether there are multiple IAB donors and nodes 101 to 106 whose received radio wave strength is equal to or greater than a predetermined threshold. If the result of the determination in S501 shows that multiple donors and nodes 101 to 106 are not detected, the process in S502 is executed. If multiple donors and nodes 101 to 106 are detected, the process in S503 is executed. In S502, an attempt is made to connect to the IAB donor and nodes 101 to 106 with the best RSSI among the detected nodes.

[0070] In S503, it is determined whether or not there is an IAB donor 101 or fixed IAB nodes 102, 103 among the IAB donors and nodes 101 to 106 whose received radio wave intensity is equal to or greater than the threshold. If the determination result in S503 indicates that the IAB donor 101 or fixed IAB nodes 102, 103 is not detected, the determination in S505 is executed; if they are detected, the process in S504 is executed.

[0071] In S504, connection processing is performed with the IAB donor 101 and the fixed IAB nodes 102 and 103 with the best received radio wave strength.

[0072] In S505, it is determined whether there are multiple MBSRs 104 to 106 that have a received signal strength equal to or greater than the threshold and a minimum number of MBSR hops. If the result of the determination in S505 is that multiple MBSRs are not detected, the process of S506 is executed; if multiple MBSRs are detected, the process of S506 is executed.

[0073] In S506, connection processing is performed with an MBSR (for example, MBSR 104) that is a node whose received radio wave intensity is equal to or greater than a threshold and has the smallest number of MBSR hops.

[0074] In S507, connection processing is performed with the MBSR 104 to 106 with the maximum received radio wave strength among the nodes with the minimum number of MBSR hops and with received radio wave strength equal to or greater than the threshold.

[0075] FIG. 6 is a flowchart showing an example of calculation of the MBSR hop count and transmission processing in the MBSR 107.

[0076] The process shown in FIG. 6 and described here is executed in the hop count calculation unit 306 after the MBSR 107 executes connection processing with the IAB donor and node (for example, the MBSR 104) and establishes an RRC link in S413.

[0077] At S600, an RRC connection is established in the MBSR 107.

[0078] In S601, it is determined whether the connection destination of the MBSR 107 is an MBSR (for example, MBSRs 104 to 106), and if it is an MBSR, the process of S603 is executed, and if not, the process of S602 is executed.

[0079] In S602, the MBSR 107 sets the MBSR hop count of its own station to one.

[0080] In S603, the MBSR 107 adds 1 to the MBSR hop count transmitted by the MBSR (e.g., MBSR 104) connected to its upper level. For example, when the MBSR 107 connects to the MBSR 104, the MBSR 107 adds 1 to the MBSR hop count of 1 broadcast by the MBSR 104, and the MBSR 107 sets the MBSR hop count to 2.

[0081] In S604, it is determined whether or not there are any IAB nodes 104-106 that are out of service in the upstream MBSR, and if there are, the process of S605 is executed. If there are no IAB nodes, the process of S606 is executed. Here, the determination in S604 uses mobility information included in the connection continuity information broadcast by the upstream MBSR 104. In other words, in this embodiment, the connection continuity information may include both the MBSR hop count and mobility information.

[0082] In S605, the number of stopped MBSRs is subtracted from the MBSR hop count in the MBSR 107. For example, if the MBSR 104 is stopped, the MBSR 107 subtracts 1 from the MBSR hop count of 2 and broadcasts 1 as the MBSR hop count as connection continuity information.

[0083] In S606, the MBSR 107 transmits the MBSR hop count as connection continuity information.

[0084] In the above example of the MBSR hop count calculation process, it is assumed that mobility information is included in the connection continuity information. However, this is not a limitation, and for example, mobility information may not be included in the connection continuity information. In this case, each MBSR 104-107 may determine whether or not its own station is stopped, and if it is stopped, it may subtract one from the MBSR hop count to be broadcast and include it in the broadcast signal and transmit it. Furthermore, if there is an IAB node 104-106 that updates its mobility information from a stopped state to a moving state, it may update the MBSR hop count in S605. Furthermore, if mobility information is not broadcast, the MBSR hop count to be broadcast by each MBSR 104-107 may be updated in response to the status update from a stopped state to a moving state.

[0085] In this embodiment, when only MBSRs 104-106 are detected as connection destination candidates with received radio wave strength above a threshold, UE 110 and MBSR 107 can connect to MBSR 104, which has a small MBSR hop count and a low risk of connection loss. Furthermore, MBSRs 104-107 calculate the MBSR hop count and transmit the calculated MBSR hop count in broadcast information as connection continuity information, allowing MBSR 107 to determine MBSR 104 with a low risk of connection loss. Furthermore, by including mobility information in the connection continuity information, it becomes possible to manage the MBSR hop count according to the movement or stop state of MBSRs 104-106 connected to the higher-level node.

[0086] The connection continuity information including the MBSR hop count and mobility information may be added to the mbsr-continuity-info field of the mbsr-Cellinfo in the SIB1 broadcast signal, or may be added to a reserved bit or field in another SSB or MIB.

[0087] As mentioned above, when MBSR implements multi-hop connections, there is a high risk of disconnection for UEs and MBSRs that connect via multiple MBSRs as higher-level nodes. Release 18 specifies that MBSR operation is limited to single-hop connections from IAB donors. However, support for multi-hop connections in MBSR is being discussed in Release 19, and future versions of MBSR may support this.

[0088] Furthermore, attempts to select a connection destination based on link quality, congestion, and number of hops at the upper connection node are known (Patent Document 2), but if MBSR is included in the connection destination candidates, it is necessary to consider the connection continuity of the communication link.

[0089] In this regard, according to the present embodiment, as described above, connection continuity information including the MBSR hop count is generated and transmitted in the MBSRs 104 to 106, thereby enabling a connection that takes into consideration the connection continuity of the communication link between the UE 110 and the MBSR 107. This reduces the risk of connection interruption in the UE or MBSR that passes through multiple MBSRs as higher-level connected nodes, even when the MBSR implements a multi-hop connection.

[0090] Furthermore, according to this embodiment, MBSRs 104 to 106 generate and transmit connection continuity information including mobility information, so that UE 110 and MBSR 107 can use connection continuity that takes into account the mobility information of MBSRs 104 to 106.

[0091] [Embodiment 2] In the first embodiment, an example has been described in which the UE 110 and the MBSR 107 connect to the MBSR 104 with a low risk of disconnection based on the MBSR hop count included in the broadcast signals from the IAB donor and the IAB nodes 101 to 106.

[0092] In the second embodiment, an example of connection processing will be described in which connection continuity information is included in the RACH response, which is a message when establishing an RRC connection, instead of a broadcast signal. In the following, a description of parts common to the first embodiment will be omitted.

[0093] Fig. 7 is a sequence diagram showing an example of connection processing between the UE 110 and the MBSR 107 according to this embodiment. In Fig. 7, similar to Fig. 5 shown in the first embodiment, it is assumed that the received radio wave intensity of the broadcast signals from the IAB donor and the IAB nodes 101 to 103 is lower than a predetermined threshold.

[0094] In steps S700 to S702, the MBSRs 104 to 106 transmit SSB and SIB1 as broadcast signals.

[0095] In S703, the UE 110 and the MBSR 107 receive the broadcast signals from the MBSRs 104 to 106. The UE 110 and the MBSR 107 measure the received radio wave intensity based on the broadcast signals from the IAB donors and the MBSRs 104 to 106.

[0096] In S704, the UE 110 and the MBSR 107 wake up from the sleep state to connect to the mobile network. The UE 110 and the MBSR 107 determine whether the received radio wave intensity of the MBSRs 104 to 106 is equal to or greater than a threshold.

[0097] Here, UE 110 and MBSR 107 transmit RACH preamplify messages from S705 onwards only to MBSRs 104 to 106 whose received radio wave strength is equal to or greater than the threshold. In S705, the UE 110 and the MBSR 107 transmit a preamplifier, which is a randomly selected fixed pattern, to the MBSR 106 as a RACH preamplifier message.

[0098] At S706, the MBSR 106 receives the RACH preample message.

[0099] In S707, MBSR 106 transmits a RACH response message to UE 110 and MBSR 107, notifying that it has received the RACH preample message and including transmission timing information and bandwidth allocation information. The MBSR hop count of 3 is also included in the RACH response message as connection continuity information, and the message may further include mobility information as connection continuity information.

[0100] In S709 to S716, similar to S705 to S707, the UE 110 and MBSR 107 transmit a RACH preamplify message to the MBSRs 104 and 105. The MBSRs 104 and 105 transmit a RACH response message to the UE 110 and MBSR 107, including the MBSR hop count.

[0101] In S717, the UE 110 and the MBSR 107 determine which MBSR 104 to 106 to connect to based on the number of MBSR hops from the MBSRs 104 to 106. The UE 110 and the MBSR 107 determine the MBSR 104 with the received signal strength equal to or greater than the threshold and with the smallest number of MBSR hops as the connection destination.

[0102] The sequence of S718 to S725 for establishing an RRC connection and starting data communication is the same as that shown in FIG. 4 of the first embodiment, and therefore a description thereof will be omitted.

[0103] In this embodiment, the UE 110 and the MBSR 107 transmit a RACH preamplifier message only to connection destination candidates whose received radio wave strength is equal to or greater than a threshold, and determine a connection destination according to the MBSR hop count included in the RACH response message.

[0104] Here, the connection continuity information including the MBSR hop count and mobility information may use a reserved bit in the RACH response message, or may include an mbsr-continuity-info field in the UL grant field.

[0105] [Other embodiments] In the first and second embodiments, it has been described that the MBSRs 104 to 107 transmit the MBSR hop count as connection continuity information and the stationary or moving state information as mobility information.

[0106] In addition to the above, the connection continuity information may be indication information at the level of single hop, multi-hop, or long hop according to the MBSR hop count. For example, the indication information may represent the MBSR hop count in three levels (stages): single hop when the MBSR hop count is 1, multi-hop when the MBSR hop count is 2 or 3, and long hop when the MBSR hop count is 4 or more. Furthermore, the hop count may be added to the connection continuity information in addition to the MBSR hop count, or simply the hop count may be used. Furthermore, if multiple MBSRs with the smallest MBSR hop count are detected in S507, the MBSR with the smallest hop count may be selected instead of or in addition to the determination based on the received signal strength.

[0107] The mobility information may also include the movement speed measured by the acceleration sensor 209, and the connection continuity information may include indication information of the level and time at which the connection can be maintained based on the movement speed and location information detected by the GPS control unit 308. That is, the MBSR may use the movement speed and location information as the indication information to indicate the length of time until the MBSR moves out of the specific area where service provision is unavailable. For example, the indication information may express the length of time until the MBSR moves out of the specific area where service provision is unavailable in multiple levels (stages). For example, level 1 may represent the shortest time, and level 3 may represent the longest time. Furthermore, the connection continuity information may include, as indication information, a level indicating a high risk of connection loss when the movement speed is fast and a low risk when the movement speed is slow.

[0108] 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.

[0109] In addition, the following supplementary notes are disclosed regarding the above-described embodiment.

[0110] [Appendix 1] A communication device constituting a backhaul network, a generating means for generating connection continuity information representing connection continuity related to connection links of one or more MBSRs (Mobile Base Station Relays) connected to a higher level; A communication device comprising a transmitting means for transmitting the connection continuity information to another communication device. [Appendix 2] The communication device according to claim 1, wherein the transmitting means transmits the connection continuity information by including it in an mbsr-Cellinfo field of an SIB (System Information Block) 1 or a RACH (Random Access Channel) response. [Appendix 3] The communication device according to claim 1 or 2, wherein the connection continuity information represents a first hop count, which is the hop count counting only communication devices whose type is MBSR. [Appendix 4] 4. The communication device of claim 3 operating as an MBSR, The communication device is characterized in that the generation means sets the first hop count represented by the connection continuity information generated to 1 when the communication device connected to the upper level is a base station or a fixed IAB (Integrated Access and Backhaul) node. [Appendix 5] a receiving unit configured to receive the connection continuity information generated by another communication device from another communication device connected to a higher level; The communication device according to claim 3 or 4, characterized in that, when the higher-level connection destination is an MBSR, the generation means sets the first hop count indicated by the connection continuity information generated to a value that is one greater than the first hop count indicated by the connection continuity information received from the MBSR of the connection destination. [Appendix 6] The communication device according to any one of Supplementary Notes 3 to 5, characterized in that the transmitting means further transmits mobility information of the MBSR of the connection destination in addition to the connection continuity information. [Appendix 7] The communication device described in Supplementary Note 6, characterized in that the mobility information is information regarding the movement state of the MBSR, including at least one of information indicating whether or not it is moving, information indicating whether or not it is stopped, information indicating its movement speed, and location information. [Appendix 8] The receiving means further receives the mobility information from the other communication device, 8. The communication device according to claim 6, wherein the generating means changes the connection continuity information in accordance with the mobility information received from the other communication device. [Appendix 9] The communication device described in any one of Supplementary Notes 3 to 8, characterized in that the generation means sets the first hop count represented by the connection continuity information to a value obtained by subtracting the number of MBSRs for which the mobility information is stopped in one or more MBSRs connected to an upper level. [Appendix 10] The communication device described in any one of Supplementary Notes 3 to 9, characterized in that when the mobility information in one or more MBSRs connected to an upper level is updated from a first state indicating a stop to a second state indicating moving, the generation means sets the first hop count represented by the connection continuity information to a value obtained by adding the number of MBSRs whose mobility information has been updated to the second state. [Appendix 11] The communication device according to any one of appendices 1 to 10, characterized in that the connection continuity information indicates, in addition to or instead of the first hop count, a second hop count, which is the hop count from an upper-connected base station to the own station. [Appendix 12] the connection continuity information includes level information indicating a level or time of connection continuity related to the connection link; The communication device according to any one of appendices 1 to 11, characterized in that the generation means generates the level information according to the first hop count or the level information according to the mobility information. [Appendix 13] a receiving means for receiving connection continuity information representing connection continuity related to connection links of one or more MBSRs (Mobile Base Station Relays) from another communication device connected to the one or more MBSRs; and a selection means for selecting a new upper communication device to connect to based on the connection continuity information. [Appendix 14] the receiving means receives the connection continuity information from each of the other communication devices as connection destination candidates; The communication device described in Supplementary Note 13, characterized in that when the multiple other communication devices are multiple MBSRs, the selection means selects the MBSR with the highest connection continuity represented by the connection continuity information. [Appendix 15] the connection continuity information represents a first hop count, which is a hop count counting only communication devices whose type is MBSR; 15. The communication device according to claim 13, wherein when the other communication devices are multiple MBSRs, the selection means selects an MBSR whose received radio wave strength is greater than or equal to a threshold and whose first hop count is the smallest. [Explanation of symbols]

[0111] 100 IAB Network 101 IAB donors 102, 103 IAB nodes 104~107 MBSR 110 UE 130CN 301 Signal transmitting unit (transmitting means) 302 signal receiving unit (receiving means) 303 Data Storage Unit 304 Connection control section 305 Connection destination determination unit (selection means) 306 Hop count calculation unit (generation means) 307 Movement information generation unit 308 GPS control unit

Claims

1. A communication device constituting a backhaul network, a generating means for generating connection continuity information representing connection continuity related to connection links of one or more MBSRs (Mobile Base Station Relays) connected to a higher level; A communication device comprising a transmitting means for transmitting the connection continuity information to another communication device.

2. 2. The communication device according to claim 1, wherein the transmitting means transmits the connection continuity information by including it in an mbsr-Cellinfo field of an SIB (System Information Block) 1 or a RACH (Random Access Channel) response.

3. 3. The communication device according to claim 2, wherein the connection continuity information indicates a first hop count, which is a hop count counting only communication devices whose type is MBSR.

4. 4. The communication device of claim 3, operating as an MBSR, comprising: The communication device, wherein the generation means sets the first hop count represented by the connection continuity information to 1 when the communication device connected to the upper level is a base station or a fixed IAB (Integrated Access and Backhaul) node.

5. a receiving unit configured to receive the connection continuity information generated by another communication device from another communication device connected to a higher level; The communication device described in claim 4, characterized in that when the upper connection destination is an MBSR, the generation means sets the first hop count represented by the connection continuity information generated to a value that is one greater than the first hop count represented by the connection continuity information received from the MBSR of the connection destination.

6. 6. The communication device according to claim 5, wherein said transmission means further transmits mobility information of said MBSR of said connection destination in addition to said connection continuity information.

7. The communication device according to claim 6, characterized in that the mobility information is information relating to the movement state of the MBSR, including at least one of information indicating whether or not the device is moving, information indicating whether or not the device is stopped, information indicating the speed of movement, and location information.

8. The receiving means further receives the mobility information from the other communication device, 8. The communication device according to claim 7, wherein said generating means changes said connection continuity information in accordance with said mobility information received from said other communication device.

9. The communication device according to claim 8, characterized in that the generation means sets the first hop count represented by the connection continuity information to be generated as a value obtained by subtracting the number of MBSRs for which the mobility information is stopped in one or more MBSRs connected to an upper level.

10. The communication device described in claim 8, characterized in that when the mobility information in one or more MBSRs connected to an upper level is updated from a first state indicating a stop to a second state indicating a movement, the generation means sets the first hop count represented by the connection continuity information generated to a value obtained by adding the number of MBSRs whose mobility information has been updated to the second state.

11. 11. The communication device according to claim 10, wherein the connection continuity information indicates a second hop count, which is the number of hops from an upper-connected base station to the communication device itself, in addition to or instead of the first hop count.

12. the connection continuity information includes level information indicating a level or time of connection continuity related to the connection link; 11. The communication device according to claim 10, wherein the generating means generates the level information according to the first hop count or the mobility information.

13. a receiving means for receiving connection continuity information representing connection continuity related to connection links of one or more MBSRs (Mobile Base Station Relays) from another communication device connected to the one or more MBSRs; and a selection means for selecting a new upper communication device to connect to based on the connection continuity information.

14. the receiving means receives the connection continuity information from each of the other communication devices as connection destination candidates; 14. The communication device according to claim 13, wherein when the other communication devices are a plurality of MBSRs, the selection means selects the MBSR with the highest connection continuity indicated by the connection continuity information.

15. the connection continuity information represents a first hop count, which is a hop count counting only communication devices whose type is MBSR; 15. The communication device according to claim 14, wherein when the other communication devices are multiple MBSRs, the selection means selects an MBSR whose received radio wave strength is equal to or greater than a threshold and whose first hop count is the smallest.

16. A control method for controlling communication of communication devices that configure a backhaul network, comprising: generating connection continuity information representing connection continuity related to connection links of one or more MBSRs (Mobile Base Station Relays) connected to the upper layer; a transmission step of transmitting the connection continuity information.

17. The computers of the communication devices that make up the backhaul network generating connection continuity information representing connection continuity related to connection links of one or more MBSRs (Mobile Base Station Relays) connected to the upper layer; a transmission step of transmitting the connection continuity information.

18. a receiving step of receiving connection continuity information representing connection continuity related to connection links of one or more MBSRs (Mobile Base Station Relays) from another communication device connected to the one or more MBSRs; and a selection step of selecting a new upper communication device to connect to based on the connection continuity information.

19. The computer of the communication device a receiving step of receiving connection continuity information representing connection continuity related to connection links of one or more MBSRs (Mobile Base Station Relays) from another communication device connected to the one or more MBSRs; a selection step of selecting a new upper communication device to connect to based on the connection continuity information;

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