Communication device, control method, and program

Abstract

Disclosed is a communication device characterized by including: a reception means that receives notification signals of multiple band types from a base station; and a connection control means that, when functioning as a mobile IAB node, preferentially attempts to connect to one or more base stations for transmitting, out of a first band type related to a millimeter wave and a second band type related to a wavelength longer than the millimeter wave, notification signals of the second band type.

Description

Communication device, control method, and program

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

[0002] The 3rd Generation Partnership Project (3GPP (registered trademark)) is currently standardizing IAB as a communication technology for backhaul. IAB stands for Integrated Access and Backhaul. In IAB, the radio resources used for the access line between a base station and a user equipment (UE) are also used for the backhaul line. Using IAB for the backhaul line enables a relay station (IAB node) to relay communication between a base station (IAB donor) and a UE via a radio line, thereby improving the connectivity of the radio access network. For example, in IAB, radio resources in the millimeter wave band, such as the 28 GHz band, are mainly used (Patent Document 1). IAB nodes search for broadcast signals from IAB donors or other IAB nodes to determine connections and form an IAB network.

[0003] To further improve the connectivity of wireless access networks, mobile IAB nodes are being considered for installation on 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 locally poor radio wave conditions or in congested areas.

[0004] Special table 2019-534625 publication

[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 its highly directional propagation characteristics.

[0006] The present invention has been made in consideration of at least one of the above-mentioned problems, and an object of the present invention is 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.

[0007] According to one aspect of the present invention, there is provided a communication device comprising: a receiving means for receiving broadcast signals of a plurality of band types from a base station; and 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 signals of a first band type associated with millimeter waves and a second band type associated with a wavelength longer than millimeter waves.

[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.

[0009] Fig. 1 is a diagram illustrating an example of the configuration of a wireless communication system. Fig. 2 is a hardware functional block diagram of a communication device capable of operating as a mobile IAB node. Fig. 3 is a software functional block diagram of a communication device capable of operating as a mobile IAB node. Fig. 4 is a sequence diagram illustrating an example of a cell search process of a communication device capable of operating as a mobile IAB node. Fig. 5 is a flowchart (first embodiment) illustrating an example of a cell search process of a communication device capable of operating as a mobile IAB node. Fig. 6 is a flowchart (second embodiment) illustrating an example of a cell search process of a communication device capable of operating as a mobile IAB node.

[0010] Each embodiment will be described in detail below with reference to the accompanying drawings. In the following description, the "number ***" in TS*** represents the number of the technical specification in the 3GPP standard.

[0011] The embodiments described below relate to a technology for performing appropriate communication control to form a stable IAB network when a mobile communication device (mobile IAB node) having a relay function performs a cell search. The mobile IAB node is also called an MBSR (Mobile Base Station Relay).

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

[0013] In IAB network 100, there are donors 101 and 102 that provide connections to CN 130. Donors are also called IAB donors. Communication device 103 can operate as an IAB node under certain conditions. Communication device 103 is approaching an authorized area where it can operate as an IAB node. Having entered the authorized area, communication device 103 wakes up from a sleep state to begin a search operation to form an IAB network with either donor 101 or 102.

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

[0015] In this embodiment, the bands used in IAB may be bands defined by FR1 and FR2 (which may include FR-2-2). Alternatively, radio waves from 700 MHz to 3.5 GHz, or 3.6 to 4.6 GHz, called Sub6, which are used in LTE, may be used. In the millimeter wave band, radio waves from 27 GHz to 29.5 GHz may be used. In the following description, it is assumed that IAB uses three band types: 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, IAB may use two band types: a band included in FR1 and a band included in FR2. Alternatively, IAB may use two band types: a band with a frequency lower than the millimeter wave band (a wavelength longer than the millimeter wave band) and a millimeter wave band. Furthermore, the above "frequency band used in LTE" may be read as "a frequency band lower than Sub6."

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

[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 currently 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 along 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 either of the donors 101 and 102. The donors 101 and 102 transmit broadcast signals in the LTE, Sub6, and millimeter wave bands. In addition, the donors 101 and 102 transmit a Master Information Block (MIB) and a System Information Block (SIB) as broadcast signals in each band. In this embodiment, when the communication device 103 returns from a sleep state and functions as a mobile IAB node, the communication device 103 attempts to connect preferentially to one or more donors that transmit broadcast signals of a specific band type (an example of a second band type). The specific band type includes one or more band types relating to wavelengths longer than millimeter waves.

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

[0021] In addition, when there are multiple connection candidate donors transmitting broadcast signals of a specific band type, a donor to which connection is preferentially attempted may be determined 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. In this case, connection may be preferentially attempted to a donor associated with a parameter value indicating good communication quality. Alternatively, the other parameter may be the 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, connection may be preferentially attempted to a donor transmitting a broadcast signal of the one specific band type. Furthermore, when broadcast signals from a donor for which connection is preferentially attempted can be received in multiple specific band types, connection may be preferentially attempted to a band type with a wider bandwidth.

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

[0023] The communication device 103 starts a search operation using the Sub6 and LTE band types and selects the donor 101 as the connection destination. The communication device 103 performs connection processing using Sub6, which is the band type for connecting to the donor 101 and can secure the widest bandwidth of the two, Sub6 and LTE. The communication device 103 performs RRC (Radio Resource Control) connection processing in accordance with the information in the MIB and SIB transmitted at the Sub6 frequency. The communication device 103 completes the RRC connection processing 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 broadcast signal. The UEs 110 and 111 receive the broadcast signal from the communication device 103, which has stronger radio wave strength than the donor 101, and change their connection to the communication device 103, which 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 also be an IAB node mounted on a moving object such as another vehicle, aircraft, or ship, or on a person.

[0025] 1 , the donor 102 also transmits broadcast signals in the Sub6 and LTE band types, just like the donor 101. Therefore, in this case, the communication device 103 may select the donor 102 as the connection destination instead of the donor 101. In this case, 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 the connection destination instead of the donor 101.

[0026] 1 , if the donor 101 does not transmit broadcast signals in the Sub6 and LTE bands, but transmits only broadcast signals in the millimeter wave band, the following may be true: 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.

[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 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. In other words, 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 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, communication quality information such as radio wave intensity related to the donors 101 and 102, communication control information such as operable band types, etc.

[0031] The communication quality information includes information related to communication quality. For example, the information 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 band types and frequency channels that can be acquired from the broadcast signals of the donors 101 and 102. The communication control information and communication quality information are acquired by measuring the MIB and SIB included in the broadcast signals, or the SSB described below.

[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 (fifth generation) standard. However, the wireless communication unit 203 is also applicable to standards other than 5G (e.g., 5G Advanced, 6G, etc.). 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 is also capable of measuring 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 can detect the 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 performed 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 acquire current position information including position identification 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] The GPS antenna control unit 207 controls an antenna 208 for GPS communication performed by 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.

[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. 3 can be realized by the control unit 201 executing a control program stored in the storage unit 202.

[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 3GPP standards 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 selecting unit 306 selects the band type to connect to.

[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 communication device 103 and the donors 101 and 102. The connection control unit 304 also 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 IAB node to connect to in order to form the 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, included in the broadcast signals received from the donors 101 and 102, and sends and stores the information to 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 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 destination IAB donor or IAB node based on 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 the antenna for GPS communication and calculates the current position and time from received GPS information. The GPS control unit 307 also outputs information in the NMEA (National Marine Electronics Association)-0183 format or the like, and stores the current position and time in the data storage unit 303 as necessary.

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

[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). Note that reception of the broadcast signal by the communication device 103 here may be omitted. Also, although the broadcast signal is received, decoding, analysis, etc. of the broadcast signal may be omitted. This also applies to the subsequent steps S402, S404, and S406 to S411.

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

[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 device wakes up from sleep mode and starts 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 and 102) using only the determined band type.

[0057] The communication device 103 may periodically operate the antenna control unit 204 to receive notification signals even during sleep mode, or may start receiving notification signals from the start of the search operation in S413 after waking up from sleep mode. The GPS antenna control unit 207 and GPS communication unit 206 are assumed to operate even during sleep mode 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 connect to and a band type are determined from the search results of S413. The band type is determined as one band type that can secure the widest bandwidth from communication control information such as channel information and communication quality information from the multiple band types determined in S413. For example, from the communication control information and communication quality information of the donor 101, Sub6 is determined as the band type that provides good communication quality in LTE and Sub6 and has a high-order frequency band and corresponding MCS.

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

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

[0061] In S417, the donor 101 transmits a RACH response message to the communication device 103 to notify that the RACH preamble message has been received, and to include transmission timing information and bandwidth allocation information.

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

[0063] In S419, in accordance with the transmission timing and bandwidth 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, the donor 101 transmits control information for RRC connection as an RRC connection setup message in response to the RRC connection request.

[0066] In step S422, the communication device 103 receives an RRC connection setup message, thereby completing the RRC link connection. 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 with a better communication environment.

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

[0069] Similarly, in steps 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, the station determines whether it functions as a mobile IAB node. For example, IAB node types other than mobile IAB nodes include stationary IAB nodes. If it functions as a mobile IAB node, the process of S501 is executed; if not, the process of S509 is executed.

[0074] In S501, the communication device 103 performs a search using a method other than millimeter waves to function as a mobile IAB node. This search is assumed to provide information identifying the base station or cell transmitting the broadcast signal and the received field strength of radio waves receivable from the antenna 205. On the other hand, this search is assumed to provide information not knowing the radio field strength for each band type. 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 field strength is selected from the search results.

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

[0077] In S504, a broadcast signal other than millimeter waves 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 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 connection, and the process of S503 is executed for the selected base station.

[0081] In S508, since there is no other base station to which connection can be made, the RRC connection process is started using millimeter waves.

[0082] In S509, since the node 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 field 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 mobile IAB node can provide a stable IAB network by selecting another band type rather than connecting to an IAB donor using millimeter waves, which are prone to interruptions due to movement. Furthermore, even if the mobile IAB node is stopped, control is performed to enable high-capacity communication by selecting millimeter waves, making it possible to select an appropriate band type depending on the status.

[0088] [Embodiment 2] In the first embodiment, an example has been described in which the communication device 103 performs a cell search by preferentially selecting a band type other than millimeter wave, and connects to the donor 101 using the Sub6 band type. In the second embodiment, an example will be described in which a mobile IAB node selects a band type according to status information related to mobility and performs a cell search. Below, 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 for 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. That is, if it is moving, a band type other than millimeter waves is selected with priority to connect to the base station. If it is stationary, it connects using the band that allows the widest bandwidth to be secured among the band types including millimeter waves.

[0092] Whether the own station is moving can be determined from the GPS information acquired by the GPS control unit 307. In addition to this method, it is also possible to determine from changes in distance measurement information based on triangulation through communication between multiple base stations and the mobile IAB node, the number of rotations of the IMU or wheels, changes in the image of the in-vehicle camera, etc.

[0093] The determination procedure from S602 onwards is the same as 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 attempting to connect to the donor 101, the communication device 103 may add identification information indicating that the device (own 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. If the communication device 103 functions as a mobile IAB node after the connection, the communication device 103 adds identification information indicating that the device is a mobile IAB node to the RRCSetupRequest. The additional field for the identification information can use spare of the RRCSetupRequest-IEs, randomValue of ue-identity, or spare 1 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 can be configured to indicate that the own device is a mobile node, that is, a mobile IAB node. Note that when "0" is set, it can be configured to indicate that the own device is an immobile IAB node, that is, a fixed IAB node. In this way, by using a field such as iab-TypeIndication, it becomes possible to notify other devices of information identifying whether the own device is a mobile IAB node.

[0095] Note that the addition of such identification information may be realized by adding a field such as mobileiab-StatusIndication to the 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 based on 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 the node 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.

[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] Furthermore, in the first embodiment, an example of an operation in which, upon waking up from sleep, it is determined in S500 whether to operate as a mobile IAB node is described. However, this is not limited thereto, and the IAB node may be able to switch between functioning as a fixed IAB node or a mobile IAB node based on its operation settings. In this case, the cell search shown in FIGS. 5 and 6 may be performed at the time of switching. Furthermore, the operation settings of the IAB node may be changeable based on a change input from a user or a change instruction received from a base station. For example, the operation settings of the IAB node may be changed by an operation unit of the IAB node or in response to a change instruction from a base station.

[0101] 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.

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

[0103] (Supplementary Note 1) A communication device comprising: a receiving means for receiving broadcast signals of a plurality of band types from a base station; and 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 signals of a first band type relating to millimeter waves and a second band type relating to wavelengths longer than millimeter waves.

[0104] (Supplementary Note 2) The communication device according to Supplementary Note 1, characterized in that the connection control means attempts to connect to a base station that can be connected to using the plurality of band types including the first band type and the second band type, giving priority to the second band type over the first band type.

[0105] (Supplementary Note 3) The communication device according to Supplementary Note 1 or 2, further comprising: a selection means for selecting a band type to be searched from among the plurality of band types; and an analysis means for searching for the annunciation signals of the band type to be searched selected by the selection means via the receiving means and analyzing the received annunciation signals, wherein the connection control means determines the one or more base stations to which a connection is to be preferentially attempted based on an analysis result by the analysis means; and wherein the selection means selects the second band type as the band type to be searched when functioning as a mobile IAB node.

[0106] (Supplementary Note 4) The communication device described in any one of Supplementary Notes 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.

[0107] (Supplementary Note 5) The communication device according to any one of Supplementary Notes 1 to 4, wherein the selection means changes the band type to be searched depending on the status of the device itself.

[0108] (Supplementary Note 6) The communication device according to Supplementary Note 5, wherein the status is mobility information including either moving or stopped.

[0109] (Supplementary Note 7) The communication device according to Supplementary Note 5 or 6, wherein the selection means selects the second band type as the band type to be searched when the status is moving.

[0110] (Appendix 8) The communication device described in any one of Appendices 5 to 7, characterized in that, when the status is stopped, 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 for.

[0111] (Supplementary Note 9) The communication device according to any one of Supplementary Notes 5 to 8, wherein the selection means, when the status is moving, 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.

[0112] (Supplementary Note 10) The communication device according to any one of Supplementary Notes 1 to 9, further comprising a switching means for switching between functioning as a fixed IAB node and functioning as a mobile IAB node.

[0113] (Supplementary Note 11) The communication device according to any one of Supplementary Notes 1 to 10, further comprising: a selection means for selecting a band type to be searched from the annunciation signals of the plurality of band types; and an analysis means for searching for the annunciation signals of the band type to be searched selected by the selection means via the receiving means and analyzing the received annunciation signals, wherein the connection control means determines the one or more base stations to which the connection control means will preferentially attempt to connect based on an analysis result by the analysis means, and wherein the selection means, when functioning as a fixed IAB node, selects only the first band type, or both the first band type and the second band type, as the band type to be searched.

[0114] (Supplementary Note 12) The communication device according to Supplementary Note 10 or 11, characterized in that the switching means executes the switching based on a function setting, and further comprises a change means for changing the function setting based on obtaining a change input from a user or receiving a change instruction from a base station.

[0115] (Supplementary Note 13) The communication device according to any one of Supplementary Notes 1 to 12, wherein the second band type includes at least one of a Sub6 band and an LTE band.

[0116] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0117] This application claims priority based on Japanese Patent Application No. 2023-126062, filed on August 2, 2023, the entire contents of which are incorporated herein by reference.

[0118] 100 IAB network 101, 102 Donor 103 Communication device (mobile IAB node) 110, 111 UE 130 CN 140 Bus 141 Direction of travel 201 Control unit (switching means, changing means) 202 Memory unit 203 Wireless communication unit 204 Antenna control unit 205 Antenna 206 GPS communication unit 207 GPS antenna control unit 208 Antenna 301 Signal transmission unit 302 Signal reception 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 communications device comprising: a receiving means for receiving broadcast signals of multiple band types from a base station; and 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 signals of a first band type relating to millimeter waves and a second band type relating to a wavelength longer than 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 via 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 communication device as described in claim 1 or 2, further comprising a selection means for selecting a band type to be searched from among the plurality of band types, and an analysis means for searching for the annunciation signal of the band type to be searched selected by the selection means via the receiving means and analyzing the received annunciation signal, wherein the connection control means determines the one or more base stations to which a connection will be preferentially attempted based on the analysis results by the analysis means, and wherein the selection means selects the second band type as the band type to be searched when functioning 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 notification signal of one of the second band types that can secure the widest bandwidth among the two or more second band types.

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

6. The communication device according to claim 5, wherein the status is mobility information including either moving or stationary.

7. The communication device according to claim 6, wherein said selection means selects said second band type as the band type to be searched when said status is "moving." 8. The communication device according to claim 6, characterized in that, when the status is stopped, the selection means selects only the first band type, or both the first band type and the second band type, as the band types to be searched for from among 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 the distance from the base station and the 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. 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. The communication device according to claim 10, further comprising: a selection means for selecting a band type to be searched from among the notification signals of the multiple band types; and an analysis means for searching for the notification signals of the band type to be searched selected by the selection means via the receiving means and analyzing the received notification signals, wherein the connection control means determines the one or more base stations to which the connection control means will preferentially attempt to connect based on an analysis result by the analysis means, and wherein the selection means, when functioning as a fixed IAB node, 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 among the first band type and the second band type.

12. The communication device according to claim 10 or 11, characterized in that the switching means executes the switching based on a function setting, and further has a change means for changing the function setting based on obtaining a change input from a user or receiving 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 Sub6 and LTE bands.

14. A control method for controlling communications, comprising: a receiving step of receiving broadcast 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 broadcast signals of a first band type relating to millimeter waves and a second band type relating to a wavelength longer than millimeter waves.

15. A program for causing a computer to execute the following steps: a receiving process for receiving broadcast signals of multiple band types from a base station; and a connection control process for, when functioning as a mobile IAB node, preferentially attempting to connect to one or more base stations that transmit the broadcast signals of a first band type relating to millimeter waves and a second band type relating to a wavelength longer than millimeter waves.

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