Communication device, control method, and program

Abstract

To provide a mechanism that allows an IAB node to connect to an appropriate IAB donor by narrowing down a band type used for a backhaul line and searching.SOLUTION: A communication device disclosed includes receiving means for receiving notification signals of a plurality of band types from a base station, and connection control means for, when functioning as a mobile IAB node, preferentially attempting to connect to one or more base stations that transmit notification signals of a first band type related to millimeter waves and a second band type among second band types related to wavelengths longer than millimeter waves.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] In the 3rd Generation Partnership Project (3GPP (registered trademark): 3rd Generation Partnership Project), standardization of IAB as a communication technology for backhaul is progressing. IAB is an abbreviation of Integrated Access and Backhaul. In IAB, the radio resources used for the access line between the base station and the user terminal (UE: User Equipment) are also used for the backhaul line. By using IAB for the backhaul line, the relay station (IAB node) can relay the communication between the base station (IAB donor) and the UE by the radio line, and the connectivity of the radio access network can be improved. For example, in IAB, radio resources of the millimeter wave band such as the 28 GHz band are mainly used (Patent Document 1). The IAB node searches for a broadcast signal from the IAB donor or other IAB nodes, determines the connection destination, and forms an IAB network.

[0003] To further improve the connectivity of wireless access networks, mobile IAB nodes are being considered for installation in vehicles such as buses, taxis, and trains. The use of mobile IAB nodes is expected to provide good communication services within vehicles, as well as improve communication quality in areas with poor radio wave conditions or in congested areas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2019-534625 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a mobile IAB node uses millimeter wave radio waves as the band type for the backhaul line, communication can be easily interrupted and unstable due to the strong directivity of the propagation characteristics.

[0006] The present invention has been made in consideration of at least one of the above problems. As one aspect of the present invention, an object of the present invention is to provide a mechanism for an IAB node to connect to an appropriate IAB donor by narrowing down the band types used by the backhaul line and searching for the band types. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided a communication device, comprising: a receiving unit for receiving a notification signal of a plurality of band types from a base station; When functioning as a mobile IAB node, the IAB node has a connection control means for preferentially attempting connection to one or more base stations that transmit the broadcast signal of a first band type related to millimeter waves and a second band type related to a wavelength longer than that of millimeter waves. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a mechanism that enables an IAB node to connect to an appropriate IAB donor by narrowing down the band types used by the backhaul line and searching. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Diagram 2] FIG. 2 is a hardware functional block diagram of a communication device capable of operating as a mobile IAB node. [Diagram 3] FIG. 2 is a software functional block diagram of a communication device capable of operating as a mobile IAB node. [Figure 4]FIG. 11 is a sequence diagram showing an example of a cell search process of a communication device operable as a mobile IAB node. [Diagram 5] 1 is a flowchart showing an example of a cell search process of a communication device operable as a mobile IAB node (first embodiment). [Figure 6] 11 is a flowchart showing an example of a cell search process of a communication device operable as a mobile IAB node (embodiment 2). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. In the following description, the "number ***" in TS*** indicates the number of the Technical Specification in the 3GPP standard.

[0011] Each embodiment described below relates to a technology for performing appropriate communication control to form a stable IAB network when a mobile communication device having a relay function (mobile IAB node) performs a cell search. Note that the mobile IAB node is also called MBSR (Mobile base Station Relay).

[0012] [Embodiment 1] FIG. 1 illustrates an example of a wireless communication system (IAB network 100) according to an embodiment of the present disclosure.

[0013] In the IAB network 100, there are donors 101 and 102 that provide a connection to the CN 130. The donors are also called IAB donors. The communication device 103 can operate as an IAB node under certain conditions. The communication device 103 is approaching an authorized area where it can operate as an IAB node. The communication device 103 that has moved into the authorized area returns from a sleep state to start a search operation for forming an IAB network with either the donor 101 or 102.

[0014] In NR (New Radio), frequency ranges called FR1 corresponding to 410MHz to 7125MHz, FR2-1 corresponding to 24.25GHz to 52.6GHz, and FR2-2 corresponding to 52.6GHz to 71GHz are specified. FR2-1 is also called FR2. Multiple frequency bands are specified within FR1, FR2-1, and FR2-2. For example, FR1 specifies the operating bands n1 to n105 as bands for NR, and FR2 specifies the operating bands n257 to n263. Note that FR1 includes the frequency band used in LTE (Long Term Evolution), the frequency band called Sub6, and the like. FR2 is also called millimeter wave.

[0015] In this embodiment, the bands used in the IAB may be bands defined by FR1 and FR2 (may include FR-2-2). Radio waves from 700 MHz to 3.5 GHz, and 3.6 to 4.6 GHz called Sub6, which are used in LTE, may be used. Radio waves from 27 GHz to 29.5 GHz may be used in the millimeter wave band. In the following description, the IAB will be described on the assumption that it uses three band types, namely, the frequency band used in LTE (hereinafter referred to as "LTE"), the frequency band called Sub6 (hereinafter referred to as "Sub6"), and millimeter waves. However, this embodiment is not limited to this. For example, the IAB may use two band types, a band included in FR1 and a band included in FR2. The IAB may use two band types, a band with a frequency lower than the millimeter wave band (longer wavelength than the millimeter wave band) and a millimeter wave band. The above "frequency band used in LTE" may be read as "frequency band lower than Sub6".

[0016] Here, CN is an abbreviation for Core Network, which is responsible for various processes such as authentication of the terminals UE 110 and 111 and registration of slice usage.

[0017] Since the communication device 103 has not yet started operating as an IAB node, the UEs 110 to 111 are connected to the donor 101 and are performing data communication with the CN 130.

[0018] The UEs 110 and 111 are mobile terminals used by passengers of the bus 140 .

[0019] In FIG. 1, the communication device 103 is mounted on the bus 140. In this case, the communication device 103 can function as a mobile IAB node that moves with the movement of the bus 140. When the bus 140 moves in the travel direction 141, the communication device 103 mounted on the bus 140 can receive broadcast information from both the donors 101 and 102. The donors 101 and 102 transmit broadcast signals for each band type of LTE, Sub6, and millimeter wave. In addition, the donors 101 and 102 transmit MIB (Master Information Block) and SIB (System Information Block) as broadcast signals for each band type. In this embodiment, when the communication device 103 returns from a sleep state and functions as a mobile IAB node, it attempts to connect preferentially to one or more donors that transmit a broadcast signal of a specific band type (an example of a second band type). The specific band type includes one or more band types related to wavelengths longer than millimeter wave.

[0020] Here, "attempting connection with priority" includes attempting connection to one or more connection candidate donors transmitting a notification signal of a specific band type by searching only the specific band type. Alternatively, "attempting connection with priority" includes attempting connection to one or more connection candidate donors transmitting a notification signal of a specific band type by searching other band types in addition to the specific band type.

[0021] In addition, when there are a plurality of connection candidate donors transmitting a notification signal of a specific band type, a donor to which a connection is to be preferentially attempted may be determined from among the plurality of donors based on the value of another parameter. In this case, the other parameter may be a parameter related to communication quality such as radio wave strength, and in this case, a connection may be preferentially attempted to a donor associated with a parameter value indicating good communication quality. Alternatively, the other parameter may be a bandwidth of a specific band type. For example, assume that there are two or more specific band types, and one specific band type has a wider bandwidth than the other specific band types. In this case, a connection may be preferentially attempted to a donor transmitting a notification signal of the one specific band type. In addition, when a notification signal from one donor to which a connection is to be preferentially attempted can be received by a plurality of specific band types, a connection may be preferentially attempted to a band type having a wider bandwidth.

[0022] In FIG. 1, the communication device 103 that has returned from a sleep state selects Sub6 and LTE, excluding millimeter waves, as candidates for the band type for connecting to the base station, since the own station functions as a mobile IAB node.

[0023] The communication device 103 starts a search operation with the band types of Sub6 and LTE, and selects the donor 101 as a connection destination. The communication device 103 performs a connection process with Sub6, which can secure the widest band among Sub6 and LTE, as a band type for connecting to the donor 101. The communication device 103 executes an RRC (Radio Resource Control) connection process according to the information of the MIB and SIB transmitted with the frequency of Sub6. The communication device 103 completes the RRC connection process with the donor 101 and forms an IAB network as a mobile IAB node. The communication device 103 starts operating as an IAB node and transmits a notice signal. The UEs 110 and 111 receive the notice signal of the communication device 103, which has a stronger radio wave intensity than the donor 101, and change the connection to the communication device 103 that provides a better radio wave environment. The UEs 110 and 111 continue data communication with the CN 130 via the communication device 103 and the donor 101 in a stable environment.

[0024] In this embodiment, the communication device 103 is assumed to be mounted on the bus 140, but may be an IAB node mounted on a moving object such as another vehicle, aircraft, or ship, or on a person.

[0025] In the above description of FIG. 1, the donor 102 also transmits a notification signal of the band types of Sub6 and LTE, like the donor 101. Therefore, in this case, the communication device 103 may select the donor 102 as a connection destination instead of the donor 101. At this time, communication quality information such as radio wave strength and communication control information such as operable band types regarding the donors 101 and 102 obtained may be compared and considered. For example, if the donor 102 has better radio wave strength than the donor 101, the communication device 103 may select the donor 102 as a connection destination instead of the donor 101.

[0026] 1, if the donor 101 does not transmit the notification signal of the Sub6 and LTE band types, but transmits only the notification signal of the millimeter wave band type, the following may be performed. In this case, the communication device 103 may select the donor 102 as the connection destination instead of the donor 101.

[0027] FIG. 2 is a block diagram showing an example of the hardware configuration of the communication device 103. As shown in FIG.

[0028] The hardware configuration of the communication device 103 includes a control unit 201, a storage unit 202, a wireless communication unit 203, an antenna control unit 204, an antenna, a GPS communication unit 206, a GPS antenna control unit 207, and an antenna 208 for GPS.

[0029] 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 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, for example, by executing a control program stored in the storage unit 202. That is, the processor of the control unit 201 and the storage unit 202 function as a computer that controls the device.

[0030] The storage unit 202 includes one or more storage devices (memories), such as, for example, 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 the processing by the control unit 201. The various information may be, for example, communication quality information such as radio wave intensity related to the donors 101 and 102, communication control information such as the type of operable band, and the like.

[0031] The communication quality information includes information related to communication quality. For example, it may include a received signal strength indicator (RSSI), a reference signal received quality (RSRQ), a reference signal received power (RSRP), etc. In addition, the communication quality information may include a modulation and coding scheme (MCS), a signal to noise ratio (SNR), a communication speed, etc.

[0032] The communication control information includes information necessary for performing connection processing with the donors 101 and 102, such as a band type and a frequency channel that can be acquired from the broadcast signals of the donors 101 and 102. The communication control information and the communication quality information are acquired by measuring the MIB and SIB included in the broadcast signals, or the SSB described later.

[0033] 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, the wireless communication unit 203 is also applicable to standards other than 5G (e.g., 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.

[0034] 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 can also measure communication quality based on a signal received by the antenna 205. The antenna control unit 204 may generate, for example, an RSSI indicating received signal strength or an SNR as communication quality information indicating the measurement result of the search operation.

[0035] The communication quality may be measured using, for example, an SSB periodically transmitted (broadcast) from the donors 101 and 102. The SSB is a synchronization signal / broadcast channel block (SS / PBCH Block). The synchronization signal / broadcast channel block is composed of a synchronization signal (SS) and a physical broadcast channel (PHCH). The SSB is periodically transmitted from the base station mainly so that the UE detects a cell ID and reception timing when starting communication. In NR, the SSB is also used to measure the reception quality of each cell. The PBCH includes an MIB.

[0036] The antenna control unit 204 controls an antenna 205 used for wireless communication executed by the wireless communication unit 203. The antenna control unit 204 is also capable of measuring communication quality information.

[0037] The GPS communication unit 206 receives signals from GPS (Global Positioning System) satellites to obtain current position information including position specifying information such as longitude and latitude information, and current time information. Note that other satellite positioning systems of the GNSS (Global Navigation Satellite System) may be used instead of GPS.

[0038] A GPS antenna control unit 207 controls an antenna 208 for GPS communication performed in the GPS communication unit 206 .

[0039] FIG. 3 is a block diagram showing an example of the functional configuration of software of the communication device 103. As shown in FIG.

[0040] The communication device 103 includes a signal transmitting unit 301, a signal receiving unit 302, a data storage unit 303, a connection control unit 304, an annunciation signal processing unit 305, a band selection unit 306, and a GPS control unit 307. The functions of each block shown in FIG.

[0041] 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 IAB nodes (e.g., donors 101 and 102) and the UEs (e.g., UEs 110 to 112). 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.

[0042] The signal receiving unit 302 receives a broadcast signal from an IAB donor or another IAB node (e.g., donors 101 and 102). The signal receiving unit 302 controls to receive signals of all band types, including LTE, Sub6, and millimeter wave, until the band type to be connected is selected by the band selecting unit 306.

[0043] The data storage unit 303 stores various programs and various data (various information) in the storage unit 202 to hold them.

[0044] The connection control unit 304 performs processes related to the connection of the IAB network, such as transmitting and receiving Radio Resource Control (RRC) messages between the donors 101 and 102. The connection control unit 304 further performs processes related to the connection with the UEs 110 and 111 and the connection with the CN 130. The connection control unit 304 controls the cell search operation of the communication device 103, and determines an IAB donor or an IAB node to connect to in order to form an IAB network. In this embodiment, the donor 101 is determined as the connection destination.

[0045] The connection control unit 304 controls the antenna control unit 204 during wireless communication. The connection control unit 304 acquires communication quality information from the antenna control unit 204, and sends the acquired communication quality information to the data storage unit 303.

[0046] The broadcast signal processing unit 305 extracts communication control information, such as operable band types and channel information, contained in the broadcast signals received from the donors 101 and 102, and sends and stores the information in the data storage unit 303. For example, the communication control information is used when establishing an RRC link executed by the connection control unit 304. The channel information includes communication control information, such as information indicating a bandwidth and resource block (RB) allocation information.

[0047] The band selection unit 306 selects a band type that can secure the widest bandwidth between the local station and the connected IAB donor or IAB node from the communication control information and communication quality information. The selected band type is sent to the connection control unit 304 to execute the RRC connection process using the selected band type.

[0048] The GPS control unit 307 performs communication in accordance with the GPS standard. The GPS control unit 307 also controls an antenna for GPS communication, calculates the current position and time from received GPS information, 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.

[0049] The communication device 103 determines, based on the current location acquired by the GPS control unit 307, whether the device is located inside or outside the permitted area in which the device can operate as an IAB node.

[0050] FIG. 4 is a sequence diagram showing an example of a cell search process of the communication device 103 according to this embodiment.

[0051] In S400, the donor 101 transmits a broadcast signal in the LTE band type (an example of the second band type). Here, reception of the broadcast signal by the communication device 103 may be omitted. Also, although the broadcast signal is received, decoding and analysis of the broadcast signal may be omitted. This also applies to the following S402, S404, and S406 to S411.

[0052] In S402, the donor 101 transmits a notification signal in the Sub6 band (an example of the second band).

[0053] In S404, the donor 101 transmits a notification signal in the millimeter wave band type (an example of the first band type).

[0054] Similarly, in steps S406 to S411, the donor 102 transmits a notification signal in the LTE, Sub6, or millimeter wave band.

[0055] In S412, the communication device 103 moves into the permitted area, so that the communication device 103 wakes up from sleep and starts the operation for connecting to the mobile network.

[0056] In S413, since the communication device 103 functions as a mobile IAB node, it determines the band type to be LTE and Sub6, which are band types excluding millimeter waves, and starts searching for base stations (e.g., donors 101, 102) only in the determined band types.

[0057] The communication device 103 may periodically operate the antenna control unit 204 even during sleep to receive the notification signal, or may start receiving the notification signal from the start of the search operation of S413 after returning from sleep. The GPS antenna control unit 207 and GPS communication unit 206 are assumed to be operating even during sleep so that it is always possible to determine whether the communication device 103 is located inside or outside the permitted area.

[0058] In S414, a base station (for example, donor 101) to be connected and a band type are determined from the search results of S413. The band type is determined to be one band type that can secure the widest bandwidth from communication control information such as channel information and communication quality information from among the multiple band types determined in S413. For example, Sub6 is determined from the communication control information and communication quality information of the donor 101 as the band type that has good communication quality for LTE and Sub6 and has a high-order frequency band and corresponding MCS.

[0059] In S415, the communication device 103 transmits a preamplifier, which is a fixed pattern randomly selected in accordance with the band type determined in S414, to the donor 101 as a RACH preamplifier message.

[0060] At S416, the donor 101 receives the RACH preample message.

[0061] In S417, the donor 101 transmits a RACH response message to the communication device 103, notifying the communication device 103 of the receipt of the RACH preample message and including transmission timing information and band allocation information.

[0062] In S418, the communication device 103 receives the RACH response message.

[0063] In S419, in accordance with the transmission timing and band allocation information of the RACH response message received by the communication device 103 in S418, the communication device 103 transmits an RRC connection request to the donor 101. The RRC connection request is an RRC connection request message.

[0064] At S420, the donor 101 receives an RRC connection request message.

[0065] In S421, in response to the RRC connection request, the donor 101 transmits control information for the RRC connection as an RRC connection setup message.

[0066] In S422, the communication device 103 completes the RRC link connection by receiving the RRC connection setup message. In this case, the communication device 103 starts transmitting a broadcast signal as an IAB node.

[0067] At this time, the UE 110 and UE 111 receive a notification signal from the communication device 103, and change the connection from the currently connected donor 101 to the communication device 103 having a better communication environment.

[0068] In S423 to S426, the UE 110, which has completed the connection change, performs data communication with the CN 130 via the communication device 103 and the donor 101.

[0069] Similarly, in S427 to S430, the UE 111 performs data communication with the CN 130 via the communication device 103 and the donor 101.

[0070] At this time, communication is performed in a band type of, for example, Sub6 as a backhaul line between the communication device 103 and the donor 101.

[0071] FIG. 5 is a flowchart showing an example of a cell search by the communication device 103 according to this embodiment.

[0072] Here, a processing flowchart of the cell search operation in S413 and S414 will be described.

[0073] In S500, it is determined whether the local station functions as a mobile IAB node. For example, there are IAB node types other than mobile IAB nodes, such as stationary IAB nodes. If it functions as a mobile IAB node, the process of S501 is executed, and if not, the process of S509 is executed.

[0074] In S501, since the communication device 103 functions as a mobile IAB node, a search is performed using a method other than millimeter waves. In this search, it is assumed that information for identifying the base station or cell transmitting the broadcast signal and the received electric field strength of the radio waves that can be received from the antenna 205 are known. On the other hand, in this search, it is assumed that the radio field strength for each band type is not known. In other words, communication quality information and communication control information for each band type will not be clear until the SSB is measured and the MIB and SIB are analyzed to extract the information.

[0075] In S502, the base station with the strongest received signal strength is selected from the search results.

[0076] In S503, it is determined whether or not a notification signal other than millimeter waves can be received from the base station selected in S502. Whether or not a notification signal other than millimeter waves can be received is determined by analyzing the information in the MIB or SIB. If a notification signal other than millimeter waves can be received, the process of S504 is executed, and if not, the process of S506 is executed.

[0077] In S504, a broadcast signal other than millimeter wave is received, SSB is measured, and the MIB and SIB are analyzed to obtain communication quality information and communication control information for each band type.

[0078] In S505, the band type that can secure the widest bandwidth is determined from the communication quality information and communication control information of the band types other than millimeter waves, and the RRC connection process is started.

[0079] In S506, it is determined whether or not a notification signal other than millimeter waves from another base station can be received. If the notification signal can be received, the process of S507 is executed, and if not, the process of S508 is executed.

[0080] In S507, another base station is selected as a candidate for the connection destination, and the process of S503 is executed for the selected base station.

[0081] In S508, since there are no other base stations to which the mobile station can connect, the mobile station starts the RRC connection process using millimeter waves.

[0082] In S509, since the device does not operate as a mobile IAB node, a search is performed in all band types.

[0083] In S510, the base station with the strongest received signal strength is selected from the search results.

[0084] In S511, the MIB and SIB are analyzed for all band types, the SSB is measured, communication quality information and communication control information for each band type are obtained, and S505 is executed.

[0085] In S505, the band type that can secure the widest bandwidth is determined from the communication quality information and communication control information of all band types, and the RRC connection process is started.

[0086] It should be noted that the candidate band types differ when the process of S505 is executed after S504 and when S505 is executed after S511.

[0087] According to this embodiment, a stable IAB network can be provided by selecting another band type rather than connecting to an IAB donor using millimeter waves, which are prone to interruption when a mobile IAB node moves. Furthermore, even if the mobile IAB node is stopped, control is performed to enable high-capacity communication by selecting millimeter waves, and an appropriate band type can be selected according to the status.

[0088] [Embodiment 2] In the first embodiment, an example has been described in which the communication device 103 preferentially selects a band type other than millimeter wave to perform a cell search, and connects to the donor 101 with the Sub6 band type. In the second embodiment, an example will be described in which the mobile IAB node selects a band type according to status information related to mobility, and executes a cell search. In the following, a description of parts common to the first embodiment will be omitted.

[0089] FIG. 6 is a flowchart illustrating an example of a cell search process of a mobile IAB node according to an embodiment of the present invention.

[0090] In S600, it is determined whether the local station functions as a mobile IAB node.

[0091] In S601, it is determined whether the station is moving. If it is moving, the determination in S601 is executed, and if it is stationary, the process in S610 is executed. In other words, if it is moving, a band type other than millimeter wave is selected with priority to connect to the base station. If it is stationary, it connects to the band that can secure the largest bandwidth among the band types including millimeter wave.

[0092] Whether the own station is moving or not can be determined from GPS information acquired by the GPS control unit 307. In addition, this is not limited to this method, and it can also be determined from changes in distance measurement information based on triangulation by communication between multiple base stations and the mobile IAB node, changes in the IMU or wheel rotation speed, changes in the image of the vehicle-mounted camera, etc.

[0093] The determination procedure from S602 onwards is similar to the cell search processing procedure in FIG. 5 of the first embodiment, and therefore a description thereof will be omitted.

[0094] In the second embodiment, when the communication device 103 attempts to connect to the donor 101, the communication device 103 may add identification information indicating that the device itself (local station) is a mobile IAB node. For example, the communication device 103 generates a connection request (RRCSetupRequest) to the donor 101. The RRCSetupRequest is a message for requesting establishment of an RRC connection. When the communication device 103 functions as a mobile IAB node after the connection, the device adds identification information indicating that the device itself is a mobile IAB node to the RRCSetupRequest. The identification information addition field can use spare or randomValue of ue-identity of RRCSetupRequest-IEs, and spare1 to 6 of establishmentCause. For example, any of spare1 to 6 is newly defined as a field such as iab-TypeIndication. Then, when "1" is set in the iab-TypeIndication field, it may be configured to indicate that the device itself is a node that can move, that is, a mobile IAB node. Note that when "0" is set, it may indicate that the IAB node is not mobile, i.e., that the IAB node is fixed. In this way, by using a field such as iab-TypeIndication, it becomes possible to notify other devices of information that identifies whether the own device is a mobile IAB node or not.

[0095] Note that the addition of such identification information may be realized by adding a field such as mobileiab-StatusIndication to an RRCSetupComplete message as specified in TS38.331.

[0096] [Other embodiments] In the second embodiment, an example has been described in which a cell search is performed in which a band type is selected according to status information related to the mobility of a mobile IAB node.

[0097] In addition to the determination according to the mobility in S601 in the second embodiment, even if the mobile IAB node is moving, millimeter waves may be included as a band type to be searched depending on the distance from the base station to which it is connected and the moving speed. That is, the band type may be determined by further adding the distance from the base station and the moving speed as status information and comparing them with a predetermined threshold value.

[0098] Since millimeter waves have a large free propagation loss, a highly directional antenna 205 is used to extend the communication distance. Therefore, it is necessary to follow the movement of the communication device 103 while switching the direction of the antenna 205.

[0099] However, if the distance from the base station is short, or the moving speed is slow, or depending on a combination of these conditions, a backhaul line using millimeter waves may be formed.

[0100] In addition, in the first embodiment, an operation example in which it is determined whether to operate as a mobile IAB node in S500 when returning from sleep has been shown. However, this is not limited to this, and it may be possible to switch between functioning as a fixed IAB node or a mobile IAB node based on the operation setting of the IAB node. In this case, the cell search shown in Figs. 5 and 6 may be executed at the time of switching. Also, the operation setting of the IAB node may be changeable based on acquisition of a change input from a user or receipt of a change instruction from a base station. For example, the operation setting of the IAB node may be changed by an operation unit of the IAB node or may be changed in response to a change instruction from a base station.

[0101] Although each embodiment has been described above in detail, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. In addition, it is also possible to combine all or a plurality of the components of the above-described embodiments.

[0102] In addition, the following supplementary notes are disclosed regarding the above embodiment.

[0103] (Appendix 1) A receiving means for receiving a report signal of a plurality of band types from a base station; a connection control means for, when functioning as a mobile IAB node, preferentially attempting to connect to one or more base stations that transmit the broadcast signal of a first band type associated with millimeter waves and a second band type associated with a wavelength longer than that of millimeter waves. (Appendix 2) The communication device described in Appendix 1, characterized in that the connection control means attempts to connect to a base station that can be connected to using the multiple band types including the first band type and the second band type, by prioritizing the second band type over the first band type. (Appendix 3) a selection means for selecting a band type to be searched from among the plurality of band types; an analysis means for searching for the beacon signal of the search target band type selected by the selection means via the reception means and analyzing the received beacon signal, The connection control means determines, based on a result of the analysis by the analysis means, the one or more base stations to which a connection is to be preferentially attempted; 3. The communication device according to claim 1, wherein the selection means, when functioning as a mobile IAB node, selects the second band type as the band type to be searched. (Appendix 4) The communication device according to any one of claims 1 to 3, characterized in that, when there are two or more second band types, the connection control means attempts preferential connection to one or more base stations that transmit the annunciation signal of one of the second band types that can secure the widest bandwidth among the two or more second band types. (Appendix 5) 5. The communication device according to claim 1, wherein the selection means changes the band type to be searched depending on a status of the communication device itself. (Appendix 6) The communication device according to claim 5, wherein the status is mobility information including either moving or stopped. (Appendix 7) The communication device according to claim 5 or 6, wherein the selection means selects the second band type as the band type to be searched when the status is moving. (Appendix 8) The communication device according to any one of appendixes 5 to 7, wherein the selection means, when the status is stopped, selects only the first band type, or both the first band type and the second band type, as the band type to be searched, out of the first band type and the second band type. (Appendix 9) The communication device according to any one of appendixes 5 to 8, wherein when the status is moving, the selection means selects, based on a distance from a base station and a moving speed, whether to select only the first band type or both the first band type and the second band type as the band type to be searched, out of the first band type and the second band type. (Appendix 10) 10. The communication device according to any one of claims 1 to 9, further comprising a switching means for switching between functioning as a fixed IAB node or a mobile IAB node. (Appendix 11) a selection means for selecting a band type to be searched from among the notification signals of the plurality of band types; an analysis means for searching for the beacon signal of the search target band type selected by the selection means via the reception means and analyzing the received beacon signal, The connection control means determines, based on a result of the analysis by the analysis means, the one or more base stations to which the connection control means will preferentially attempt to connect; The communication device according to any one of claims 1 to 10, characterized in that, when functioning as a fixed IAB node, the selection means selects only the first band type, or both the first band type and the second band type, as the band type to be searched, from the first band type and the second band type. (Appendix 12) The switching means executes the switching based on a function setting, 12. The communication device according to claim 10 or 11, further comprising a change means for changing the function setting based on acquisition of a change input from a user or receipt of a change instruction from a base station. (Appendix 13) 13. The communication device according to claim 1, wherein the second band type includes at least one of a Sub6 band and an LTE band. [Explanation of symbols]

[0104] 100 IAB Network 101, 102 Donor 103 Communication Equipment (Mobile IAB Node) 110, 111UE 130CN 140 Bus 141 Direction of operation 201 Control unit (switching means, changing means) 202 Storage section 203 Wireless Communication Department 204 Antenna control section 205 Antenna 206 GPS Communication Unit 207 GPS antenna control unit 208 Antenna 301 Signal Transmitter 302 Signal receiving unit (receiving means) 303 Data Storage Unit 304 Connection control unit (connection control means) 305 Notification signal processing unit (analysis means) 306 Band selection unit (selection means) 307 GPS control unit

Claims

1. A receiving means for receiving a report signal of a plurality of band types from a base station; a connection control means for, when functioning as a mobile IAB node, preferentially attempting connection to one or more base stations that transmit the broadcast signal of a first band type associated with millimeter waves and a second band type associated with a wavelength longer than that of millimeter waves.

2. The communication device according to claim 1, characterized in that the connection control means attempts to connect to a base station that can be connected to using the multiple band types including the first band type and the second band type by prioritizing the second band type over the first band type.

3. a selection means for selecting a band type to be searched from among the plurality of band types; an analysis means for searching for the notification signal of the search target band type selected by the selection means via the reception means and analyzing the received notification signal, The connection control means determines, based on a result of the analysis by the analysis means, the one or more base stations to which a connection is to be preferentially attempted; 3. The communication device according to claim 1, wherein the selection unit selects the second band type as the band type to be searched when the communication device functions as a mobile IAB node.

4. The communication device according to claim 3, characterized in that, when there are two or more second band types, the connection control means attempts preferential connection to one or more base stations that transmit the annunciation signal of one of the second band types that can secure the widest bandwidth among the two or more second band types.

5. 4. The communication device according to claim 3, wherein the selection means changes the band type to be searched depending on a status of the communication device itself.

6. The communication device according to claim 5 , wherein the status is mobility information including one of "moving" and "stopped."

7. 7. The communication device according to claim 6, wherein the selection means selects the second band type as the band type to be searched when the status is "moving."

8. 7. The communication device according to claim 6, wherein the selection means, when the status is stopped, selects only the first band type, or both the first band type and the second band type, as the band type to be searched for, out of the first band type and the second band type.

9. The communication device according to claim 6, characterized in that, when the status is moving, the selection means selects, based on a distance from a base station and a moving speed, whether to select only the first band type, or to select both the first band type and the second band type, as the band type to be searched, out of the first band type and the second band type.

10. 2. The communication device according to claim 1, further comprising a switching means for switching between functioning as a fixed IAB node and functioning as a mobile IAB node.

11. a selection means for selecting a band type to be searched from among the notification signals of the plurality of band types; an analysis means for searching for the notification signal of the search target band type selected by the selection means via the reception means and analyzing the received notification signal, The connection control means determines the one or more base stations to which the connection control means will preferentially attempt to connect based on the analysis result by the analysis means; 11. The communication device according to claim 10, wherein, when functioning as a fixed IAB node, the selection means selects, of the first band type and the second band type, only the first band type, or both the first band type and the second band type, as the band type to be searched.

12. The switching means executes the switching based on a function setting, 12. The communication device according to claim 10, further comprising a change unit that changes the function setting based on acquisition of a change input from a user or receipt of a change instruction from a base station.

13. The communication device according to claim 1 , wherein the second band type includes at least one of a Sub6 band and an LTE band.

14. A control method for controlling communication, comprising: a receiving step of receiving report signals of a plurality of band types from a base station; a connection control step of, when functioning as a mobile IAB node, preferentially attempting connection to one or more base stations that transmit the broadcast signal of a first band type associated with millimeter waves and a second band type associated with a wavelength longer than that of millimeter waves; A control method comprising the steps of:

15. a receiving step of receiving, by a computer, report signals of a plurality of band types from a base station; and a connection control step of, when functioning as a mobile IAB node, preferentially attempting to connect to one or more base stations that transmit the notification signal of a first band type associated with millimeter waves and a second band type associated with a wavelength longer than that of millimeter waves.

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