Base station, repeater, terminal, and wireless communication system

Abstract

The purpose of the present invention is to provide a method for efficiently controlling a specific communication device taking into account the nature of the specific communication device. This base station has a transmission unit and a control unit. The transmission unit is capable of transmitting the first signal of a radio resource control (RRC) layer to a communication device. The control unit is capable of exercising control so as to determine whether or not to transmit the second signal of the RRC layer to the communication device, in accordance with whether the communication device is of a specific type or not.

Description

Base station, repeater, terminal and wireless communication system

[0001] The present invention relates to a base station, a repeater, a terminal, and a wireless communication system.

[0002] In today's networks, traffic from mobile devices (smartphones and feature phones) accounts for the majority of network resources, and the traffic used by mobile devices is expected to continue to expand in the future.

[0003] In addition to traffic used by mobile devices, IoT (Internet of Things) services (e.g., transportation systems, smart meters, and monitoring systems for devices) are also being developed, and networks are being required to support services with diverse requirements. In order to accommodate such diverse services, the communication standards for fifth-generation mobile communications (5G or NR (New Radio)) (for example, Non-Patent Documents 15 to 42) include, for example, standard technologies for 4G (fourth-generation mobile communications) (for example, Non-Patent Documents 1 to 14), as well as eMBB (Enhanced Mobile Broadband), Massive MTC (Machine Type Communications), and URLLC (Ultra-Reliable AND Low Latency Communication). The standards are being developed assuming support for many use cases classified as such.

[0004] In the 5G communication standard, two types of radio bearers, a signaling radio bearer (SRB) and a data radio bearer (DRB), are established for communication. The signaling radio bearer (SRB) is a bearer mainly used for transmitting and receiving RRC message signals. There are also multiple types of signaling radio bearers, such as SRB0 used when transmitting RRC (Radio Resource Control) messages using a CCCH (Common Control CHannel) and SRB1 used for transmitting RRC messages using a DCCH (Dedicated Control CHannel). SRB1 is configured in the terminal, for example, in accordance with the configuration information of SRB1 included in the RRC setup message via SRB0.

[0005] In addition, a plurality of data radio bearers can be established for the data radio bearer, and a Packet Data Convergence Protocol (PDCP) entity, a Radio Link Control (RLC) entity, and a logical channel can be established for each of the plurality of data radio bearers.

[0006] The 3GPP (registered trademark) working group aims to expand the coverage area, and has therefore listed NC (Network Controlled) repeater as a study item for Release 18 (Non-Patent Document 43).

[0007] The NC repeater has a function of relaying communications between a base station and a terminal, for example, amplifying a signal transmitted from the base station and transmitting it to the terminal. Note that the NC repeater is expected to be the subject of active discussion in the future.

[0008]

[0009] When using an NC repeater to expand coverage, it is necessary to consider how to control the NC repeater. However, because discussions on the NC repeater are just beginning, details regarding the control of the NC repeater have not yet been decided, and discussions regarding control that takes into account the characteristics of the NC repeater have not progressed. The same issue can be considered for similar repeaters and devices other than the NC repeater.

[0010] The disclosed technology has been made in view of the above, and aims to provide a method for efficiently controlling a communication device such as an NC repeater.

[0011] In one aspect, a base station is provided that includes: a transmitter unit that can transmit a first signal of an RRC (Radio Resource Control) layer to a communication device; and a controller that controls the transmitter unit to determine whether to transmit a second signal of the RRC layer to the communication device after the first signal, depending on whether the communication device is of a specific type.

[0012] It is possible to provide a base station, a repeater, a wireless communication system, etc. that efficiently controls devices such as an NC repeater.

[0013] FIG. 1 is a diagram showing an example of a network configuration according to a first embodiment. FIG. 2 is a diagram showing an example of a functional configuration of a base station in a wireless communication system according to the first embodiment. FIG. 3 is a diagram showing an example of a functional configuration of a repeater in the wireless communication system according to the first embodiment. FIG. 4 is a diagram showing an example of a functional configuration of a terminal in the wireless communication system according to the first embodiment. FIG. 5 is a diagram showing an example of an operation flow of a base station according to the first embodiment. FIG. 6 is a diagram showing an example of a procedure in which a base station and a terminal establish an RRC connection according to a second embodiment. FIG. 7 is a diagram showing an example of a procedure in which a base station and a repeater establish an RRC connection according to the second embodiment. FIG. 8 is a diagram showing an example of an operation flow of a base station according to the second embodiment. FIG. 9 is a diagram showing a first example when the method according to the second embodiment is reflected in the specification (TS 38.331 (Non-Patent Document 28)). FIG. 10 is a diagram showing a second example when the method according to the second embodiment is reflected in the specification (TS 38.331 (Non-Patent Document 28)). FIG. 11 is a diagram showing an example of a procedure in which a base station and a repeater establish an RRC connection according to a third embodiment. Fig. 12 is a diagram showing an example of a procedure for a base station and a repeater to establish an RRC connection in embodiment 4. Fig. 13 is an example of a hardware configuration diagram of a base station in a wireless communication system. Fig. 14 is an example of a hardware configuration diagram of a repeater in a wireless communication system. Fig. 15 is an example of a hardware configuration diagram of a terminal in a wireless communication system.

[0014] The present embodiment will be described in detail below with reference to the drawings. The problems and embodiments described in this specification are merely examples and do not limit the scope of the present application. In particular, even if the expressions used are different, the technology of the present application can be applied as long as they are technically equivalent, and do not limit the scope of the present application. Furthermore, each embodiment can be appropriately combined within the scope of not causing contradictions in the processing content. Furthermore, the terminology used and the technical content described in this specification may be appropriately used from the terminology and technical content described in specifications and contributions as communication standards such as 3GPP. Examples of such specifications are those described in Non-Patent Documents 1 to 42.

[0015] Hereinafter, embodiments of a base station, a repeater, a terminal, and a wireless communication system disclosed in the present application will be described in detail with reference to the accompanying drawings. Note that the disclosed technology is not limited to the following embodiments.

[0016] [Problem] Before describing each embodiment, the problem in the prior art will be described. Please note that this problem was newly discovered by the inventors as a result of careful consideration of the prior art, and was not previously known.

[0017] IAB (Integrated Access and Backhaul) is a communication technology that uses a relay (relay device) (see, for example, Non-Patent Document 24). In IAB, in order to configure an RRC connection between a base station and an IAB node, RRC Connection Establishment, a security mode command message, and RRC connection Reconfiguration are performed, and, for example, SIB1, SIB2, SIB3, DRB, etc. are configured. Note that the DRB may not be configured. Note that SIB0 is a bearer used when performing RRC Connection Establishment.

[0018] Also, Sidelink Relay (hereinafter referred to as SL Relay) is a communication technology that uses a relay (relay device). This is a technology in which a terminal within the coverage of a base station (hereinafter referred to as a relay terminal) relays communication between the base station and a terminal outside the coverage of the base station (hereinafter referred to as a remote terminal). In SL Relay, in order to configure an RRC connection between the base station and the relay terminal, RRC Connection Establishment, a security mode command message, and RRC connection Reconfiguration are performed, and, for example, SIB1, SIB2, SIB3, DRB, etc. are set. After that, in order to establish an RRC connection between the base station and the remote terminal via the relay terminal, an RRC Connection Establishment, a security mode command message, and an RRC connection Reconfiguration are performed, and, for example, SIB1, SIB2, SIB3, DRB, etc. are set between the base station and the remote terminal.

[0019] Note that the processing performed to configure an RRC connection with an IAB node, relay terminal, etc., as described above, is almost the same as the processing performed between a base station and a terminal. This enables the IAB node or relay terminal to process, for example, RRC messages requiring security and User Plane (U-Palen) signals between the base station and the IAB node or relay terminal, and configures, for example, SRB1, SRB2, DRB, etc. Therefore, it is considered that the IAB node or relay terminal also performs the same RRC connection processing with the base station as the terminal. Note that the base station regards the IAB node or relay terminal as a single terminal, and does not change the RRC connection method depending on the type of terminal (e.g., relay terminal, IAB node, in-coverage terminal).

[0020] On the other hand, the NC repeater is, for example, a repeater that amplifies and outputs a signal transmitted from a base station to a terminal. In short, it is sufficient if the signal transmitted from the base station to the terminal can be processed, such as by amplification. In other words, for example, U-Palen signal processing does not need to be performed. Therefore, for example, it is sufficient to configure only some signaling radio bearers (for example, configuring only SRB1), and it is possible not to configure a data radio bearer, for example. Note that SRB0 is a bearer that is determined in advance and is not configured by the base station for each terminal.

[0021] Therefore, compared to terminals that conventional base stations consider to be terminals, such as relay terminals, IAB nodes, and terminals within the coverage of the base station, it may be possible to reduce the amount of information or signals used when establishing an RRC connection.

[0022] In this way, the NC repeater is considered to have different performance from devices regarded as terminals such as IAB nodes and relay terminals. In addition, the NC repeater is considered to be controlled by the base station by an RRC configuration that is less than the RRC configuration set in the IAB node or relay terminal.

[0023] Therefore, if an RRC connection is established by simply performing the same processing as in terminals including an IAB node, a relay terminal, etc., the number of signals required to control the NC repeater and the information included in the signals will be the same as in an IAB node or a relay terminal. As a result, the signals and information that could be reduced for controlling the NC repeater cannot be reduced, and network resources cannot be used effectively.

[0024] Furthermore, if the number of signals or the information contained in the signals is reduced, it is necessary to define how the base station identifies the NC repeater, because if the base station cannot identify the NC repeater, it will perform the same processing as a normal terminal.

[0025] Furthermore, it is necessary to consider how to transmit control information (e.g., Side Control information) from the base station to the NC repeater, and how the NC repeater transmits a signal indicating a response to the base station.

[0026] Although the above description has been given based on the NC repeater as an example, the above problem is not necessarily limited to the NC repeater. It is believed that the above problem may also occur in devices used in a similar manner to the NC repeater.

[0027] In summary, if the RRC connection control performed by conventional relays and terminals is applied as is, it is considered that network resources cannot be effectively utilized. Therefore, with regard to the RRC connection between a base station and an NC repeater, it is necessary for the base station to identify the NC repeater while taking advantage of the characteristics of the NC repeater. As mentioned above, this problem was newly discovered by the inventors as a result of detailed investigation of the prior art, and was not previously known. Hereinafter, each embodiment of the present application for solving this problem will be described in order. First Embodiment

[0028] FIG. 1 shows a wireless communication system 1 according to a first embodiment. The wireless communication system 1 includes a base station 100, a repeater 200, and terminals 300A and 300B. The base station 100 forms a cell C10. The repeater 200 forms a cell C20. The terminal 300A is not present in the cell C10, but is present within the cell C20. The terminal 300B is present in the cell C10. When there is no need to distinguish between the terminals 300A and 300B, they will simply be referred to as terminals 300. The repeater 200 and the terminal 300 may be collectively referred to as a communication device.

[0029] The base station 100 may be, for example, a small radio base station such as a macro radio base station or a pico radio base station (including a micro radio base station, a femto radio base station, etc.), or may be a radio base station of various scales, and may be referred to as a radio communication device, a communication device, a transmitting device, etc. The terminal 300 may be a radio terminal such as a mobile phone, a smartphone, a PDA (Personal Digital Assistant), a personal computer, a vehicle, or any of various devices or equipment (sensor devices, etc.) having a radio communication function, and may be referred to as a radio communication device, a communication device, a receiving device, a mobile station, etc.

[0030] The base station 100 is connected to a network device (a higher-level device or another base station) not shown in the figure via a wired connection. Note that the base station 100 may be connected to the network device wirelessly instead of via a wired connection.

[0031] The base station 100 may be configured such that the wireless communication function with the terminal 300 and the digital signal processing and control functions are separated into separate devices. In this case, the device having the wireless communication function can be called an RRH (Remote Radio Head), and the device having the digital signal processing and control functions can be called a BBU (Base Band Unit). The RRHs may be installed extending from the BBU, and they may be connected by a wired connection such as optical fiber. Alternatively, they may be connected wirelessly. Instead of the aforementioned RRH and BBU, the base station 100 may be separated into, for example, two units: a Central Unit (CU) and a Distributed Unit (DU). The DU includes at least an RF radio circuit, but may also have a wireless physical layer (or Layer 1) function, a MAC (Media Access Control) layer function, and an RLC layer function.

[0032] Meanwhile, terminal 300 communicates with base station 100 via wireless communication. Terminal 300A communicates with base station 100 via repeater 200. When repeater 200 receives a signal transmitted by base station 100, it amplifies the received signal and transmits it. For example, repeater 200 receives a signal from base station 100 intended for terminal 300A, amplifies the received signal, and transmits it to terminal 300A.

[0033] If an RRC connection has not been established between base station 100 and repeater 200, base station 100 performs processing to establish an RRC connection. If an RRC connection has not been established between base station 100 and terminal 300, base station 100 performs processing to establish an RRC connection.

[0034] Next, the base station 100 will be described. An example of the functional configuration of the base station 100 is shown in Fig. 2. The base station 100 has a wireless communication unit 110, a control unit 120, a storage unit 130, and a communication unit 140.

[0035] The wireless communication unit 110 is composed of a transmitting unit 111 and a receiving unit 112, and performs wireless communication with the terminal 300. Specifically, the transmitting unit 111 transmits downlink signals, such as a random access procedure signal, an RRC layer signal, a downlink data signal, and a downlink control signal, to the terminal 300. The transmitting unit 111 also transmits downlink signals, such as a random access procedure signal, an RRC layer signal, and the like, to the repeater 200.

[0036] Furthermore, the receiving unit 112 can receive uplink signals, such as a random access procedure signal, an RRC layer signal, an uplink data signal, and an uplink control signal, transmitted from the terminal 300. Note that the receiving unit 112 may receive various amplified signals after the various signals transmitted from the terminal 300 are amplified by the repeater. Furthermore, the receiving unit 112 can receive uplink signals, such as a random access procedure signal, an RRC layer signal, and an uplink control signal, transmitted from the repeater 200.

[0037] The control unit 120 controls the base station 100. Specifically, the control unit 120 can control the establishment of an RRC connection with the repeater 200, the establishment of an RRC connection with the terminal 300, signal processing of a signal received by the receiving unit 112, creation of a transmission block (TB), mapping of the transmission block to a radio resource, and the like.

[0038] The storage unit 130 can store, for example, downstream data signals.

[0039] The communication unit 140 connects to and communicates with a network device (e.g., a higher-level device or another base station device) via a wired or wireless connection. The data signal received by the communication unit 140 and intended for the terminal 300 can be stored in the storage unit 130.

[0040] Next, the repeater 200 will be described. Fig. 3 is an example of a functional configuration diagram of the repeater 200 in the wireless communication system of the first embodiment. As shown in Fig. 3, the repeater 200 includes a communication unit 210, a control unit 220, and a storage unit 230. These components are connected to each other so as to enable input and output of signals and data in one direction or two directions. The communication unit 210 can be described as being divided into a transmission unit 211 and a reception unit 212.

[0041] The transmitter 211 transmits, for example, an RRC layer signal or an uplink signal such as an uplink control signal to the base station via an antenna. Furthermore, when the transmitter 211 receives a signal intended for the base station 100 and transmitted from the terminal 300, the transmitter 211 amplifies and transmits the received signal. Furthermore, when the transmitter 211 receives a signal intended for the terminal 300 and transmitted from the base station 100, the transmitter 211 amplifies and transmits the received signal.

[0042] The receiver 212 receives downlink signals such as RRC layer signals and downlink control signals transmitted from the base station 100. For example, when the receiver 212 receives a signal transmitted from the terminal 300 and intended for the base station 100, the receiver 212 sends the received signal to the transmitter 211. For example, when the receiver 212 receives a signal transmitted from the base station 100 and intended for the terminal 300, the receiver 212 sends the received signal to the transmitter 211.

[0043] The control unit 220 controls the repeater 200. Specifically, the control unit 220 can control the establishment of an RRC connection with the base station 100, signal processing of a signal received by the receiving unit 212, creation of a transport block (TB), mapping of the transmission block to a radio resource, and the like.

[0044] The storage unit 230 can store, for example, RRC configuration information (or setting information) related to wireless communication transmitted from the base station 100 .

[0045] Next, the terminal 300 will be described. Fig. 4 is an example of a functional configuration diagram of the terminal 300 in the wireless communication system of the first embodiment. As shown in Fig. 4, the terminal 300 includes a communication unit 310, a control unit 320, and a storage unit 330. These components are connected to each other so as to enable input and output of signals and data in one direction or two directions. Note that the communication unit 310 can be described as being divided into a transmission unit 311 and a reception unit 312.

[0046] The transmitter 311 transmits data signals and control signals by wireless communication via an antenna. Note that the antenna may be common for both transmission and reception. The transmitter 311 transmits uplink signals such as random access procedure signals, RRC layer signals, uplink data signals, and uplink control signals, for example.

[0047] The receiver 312 receives downlink signals, such as a random access procedure signal, a downlink data signal, and a downlink control signal, transmitted from the base station 100. The received signals may also include reference signals used for channel estimation and demodulation. The receiver 312 may also receive various amplified signals transmitted from the base station 100 after the various signals have been amplified by a repeater.

[0048] The control unit 320 controls the terminal 300. Specifically, the control unit 320 can control the establishment of an RRC connection with the base station 100, signal processing of signals received by the receiving unit 312, creation of transmission blocks (TBs), mapping of the transmission blocks to radio resources, and the like.

[0049] The storage unit 330 can store, for example, uplink data signals, and can also store configuration information (or setting information) related to wireless communication transmitted from the base station 100.

[0050] Next, a process in base station 100 according to the type of repeater 200 will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of an operation flow of base station 100.

[0051] The transmitter 111 of the base station 100 transmits a first signal of the RRC layer (step S1). Then, the control unit 120 of the base station 100 determines whether the destination of the first signal is a specific type of repeater (step S2). Note that a specific type of repeater may also be referred to as a specific type of communication device. Furthermore, a specific type of repeater (communication device) is, for example, an NC repeater. Furthermore, a repeater that does not fall under the specific type of repeater (communication device) is an example of a first type of communication device. Furthermore, a specific type of repeater (communication device) is an example of a second type of communication device.

[0052] If the control unit 120 of the base station 100 determines that the destination of the first signal is a specific type of repeater (communication device) (Yes in step S2), it controls the base station 100 not to transmit the second signal (step S3).

[0053] In addition, if the control unit 200 of the base station 100 determines that the destination of the first signal is not a specific type of repeater (communication device) (No in step S2), it controls the transmission of a second signal of the RRC layer (step S4).

[0054] Whether the destination is a specific type of repeater (communication device) can be notified, for example, by including information indicating that the destination is a specific type of repeater (communication device) in a response signal to the first signal and transmitting the response signal. Whether the destination is a specific type of repeater (communication device) may also be transmitted from the specific type of repeater (communication device) to the base station 100, for example, before the specific type of repeater (communication device) receives the first signal from the base station 100. For example, information indicating that the destination is a specific type of repeater (communication device) is notified by using a specific preamble in the preamble transmitted during random access. Furthermore, information indicating that the destination is a specific type of repeater (communication device) is included in a third signal transmitted to the base station 100 to request the base station 100 to transmit the first signal. When the information indicating that the destination is a specific type of repeater (communication device) is included in the third signal, an Establishment Cause parameter may be used, for example. For example, one of the spare bits of the Establishment Cause parameter described in Non-Patent Document 28 may be newly used as a bit indicating that the access is from a specific type of repeater (communication device). Specifically, by setting a bit at a specific position in the bitmap of the Establishment Cause parameter, it indicates that it is a specific type of repeater (communication device). Furthermore, when information indicating that it is a specific type of repeater (communication device) is included in the third signal, it may be implicitly notified by using, for example, the upper N bits (N is an integer) of an identifier used in the specific type of repeater (communication device) as a fixed value. Note that an example of the identifier is S-TMSI (SAE Temporary Mobile Subscriber Identity). For example, in the case of 5G, implicit notification is possible by fixing and using the upper 39 bits of the 48 bits of 5G-S-TMSI. In short, the base station may be able to identify whether the destination is a specific type of repeater (communication device) based on the upper 39 bits of the 5G-S-TMSI of repeater 200. In this case, the upper 39 bits are, for example, a value defined in advance in the specifications.The remaining 9 bits may be notified using, for example, a MAC CE (Media Access Control Control Element) or uplink control information (UCI: Uplink Control Information). The uplink control information is transmitted via a PUCCH (Physical Uplink Control Channel). Information indicating a specific type of repeater (communication device) is an example of type information.

[0055] When base station 100 recognizes that the destination is a specific type of relay (communication device), it can transmit information for controlling relay 200 using MAC CE used in downlink and downlink control information (DCI: Downlink Control Information). When using downlink MAC CE, for example, the LCID (Logical Channel Identify) of the MAC SUBHEADER is used to indicate that information for controlling relay 200 is included in the MAC CE at relay 200, and the MAC CE corresponding to the MAC SUBHEADER is transmitted including information to be transmitted to relay 200, which is a specific type of relay (communication device). In Non-Patent Document 25, the LCID of the downlink MAC SUBHEADER has multiple Reserved. Therefore, by using any one of the plurality of reserved, it is possible to indicate with the LCID that the MAC CE contains information for controlling the relay device 200. Furthermore, the downlink control information is transmitted on a PDCCH (Physical Downlink Control Channel).

[0056] Furthermore, the repeater 200 may transmit information about the repeater 200 to the MAC CE used in the uplink. The information about the repeater 200 may be, for example, all or part of the 5G-S-TMSI. Furthermore, the information about the repeater 200 included in the MAC CE used in the uplink may include, for example, the remaining bits of the 5G-S-TMSI excluding the fixed upper bits. Furthermore, at least one of the upper N bits and the lower M bits (M bits) of the 5G-S-TMSI may be fixed, and the number of bits notified in the MAC CE may be a multiple of 8 bits. In this way, it is possible to notify in L octets (L: integer) within the MAC CE. Note that one octet is 8 bits. Furthermore, for the MAC CE used in the uplink, the LCID (Logical Channel Identify) of the MAC SUBHEADER can indicate that the MAC CE contains information about the relay 200. Furthermore, the MAC CE used in the uplink may include information indicating that it is a specific type of relay (communication device) as information about the relay 200, or the uplink control information may include information indicating that it is a specific type of relay (communication device) and transmit it to the base station 100. In this case, the relay 200 only needs to transmit the MAC CE or the uplink control information before determining whether the base station 100 is a specific type of relay (communication device). Furthermore, the information about the relay 200 may be, for example, the remaining bits of the 5G-S-TMSI.

[0057] Furthermore, the repeater 200 and the terminal 300 may be collectively referred to as a communication device. This is because the base station 100 may collectively regard the repeater 200 and the terminal 300 as a terminal. Even in this case, the operation of FIG. 5 can be performed depending on whether or not the repeater 200 and the terminal 300 are a specific communication device. For example, in the case of the terminal 300, the result of step S2 in FIG. 5 is No.

[0058] As described above, in the first embodiment, after base station 100 transmits a first signal, whether to transmit a second signal is controlled depending on whether the destination of the first signal is a specific type of repeater (communication device). By controlling in this manner, when the destination is a specific type of repeater (communication device), signal transmission can be suppressed, thereby enabling effective use of network resources. Embodiment 2

[0059] In the first embodiment, an example has been described in which whether or not to transmit a second signal is controlled depending on whether or not the destination of a first signal transmitted by the base station 100 is a specific type of repeater (communication device). In the second embodiment, an example of a process for establishing an RRC connection will be described. Note that in the second embodiment, the wireless communication system, base station, repeater, and terminal are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0060] Using Figure 6, a process until the base station 100 and the terminal 300 establish an RRC connection will be described. Note that the base station 100 and the terminal 300 may receive a signal amplified by the repeater 200. Figure 6 is a diagram showing an example of a procedure by which the base station 100 and the terminal 300 establish an RRC connection. Note that the terminal 300 in Figure 6 may be any device that is considered to be a terminal, and may be, for example, a relay terminal or an IAB node. In short, the terminal 300 in Figure 6 is applicable to communication devices other than a specific type of repeater.

[0061] The transmitter 311 of the terminal 300 transmits an RRC setup request message, which is a signal of the RRC layer, to the base station 100 (step S10). Note that the RRC setup request message is transmitted via, for example, SRB0.

[0062] After receiving the RRC setup request message at the receiving unit 112, the transmitting unit 111 of the base station 100 transmits an RRC setup message, which is an RRC layer signal, to the terminal 300 (step S20). Note that the RRC setup message includes, for example, information for establishing SRB1. Also, the RRC setup message is transmitted, for example, via SRB0. Also, the RRC setup message is an example of a first signal.

[0063] When the control unit 320 of the terminal 300 receives the RRC setup message at the receiving unit 312, it establishes SRB1 according to the information for establishing SRB1, and transitions the RRC state from IDLE state to CONNECTED state (step S30).

[0064] After step S30, the transmitter 311 of the terminal 300 transmits an RRC setup complete message, which is a signal of the RRC layer (step S40). Note that the RRC setup complete message is transmitted via SRB1, for example.

[0065] After step S40, the transmitter 111 of the base station 100 transmits a security mode command message (Security Mode Command), which is a signal of the RRC layer, to the terminal 300 (step S50). Note that the security mode command message includes, for example, a security algorithm. Note that the security mode command message is transmitted, for example, via SRB1. The security mode command message is also an example of a second signal.

[0066] After step S50, the transmitter 311 of the terminal 300 transmits a security mode complete message (Security Mode Complete), which is a signal of the RRC layer (step S60), and the control unit 320 of the terminal 300 activates AS (Access Stratum) security (step S70). Note that the order of steps S60 and S70 may be reversed, or they may be performed at the same time. Note that the security mode complete message is transmitted via SRB1, for example.

[0067] Although not shown, after the transmitting unit 311 of the terminal 300 transmits the security mode complete message, a process for notifying the base station of the UE capability from the terminal may be executed.

[0068] After AS security is enabled in the terminal 300, the transmitter 111 of the base station 100 transmits an RRC reconfiguration message (RRC Reconfiguration), which is an RRC layer signal, to the terminal 300 (step S80). Note that the RRC reconfiguration message includes, for example, configuration information of a signaling radio bearer (SRB2), setting information of a cell group (configuration information of the RLC layer, MAC layer, physical Y layer, etc.), measurement setting information, configuration information of a data radio bearer, etc.

[0069] The control unit 320 of the terminal 300 establishes an SRB2 and a DRB in response to the signal received in step S80 (step S90). Then, the transmission unit 311 of the terminal 300 transmits an RRC reconfiguration complete message (RRC Reconfiguration Complete) to the base station (step S100). By performing processing between the base station 100 and the terminal 300 in this manner, an RRC connection is established between the base station 100 and the terminal 300, and it becomes possible to transmit and receive U-plane data, for example, via the DRB.

[0070] The signals or messages transmitted between step S10 and step S100 in FIG. 6 may be simply referred to as RRC layer signals or RRC layer messages.

[0071] Next, the process until the base station 100 and the repeater 200 establish an RRC connection will be described using Figure 7. Note that the same reference numerals are assigned to the same contents as in Figure 6. However, the information contained in the signal may change as necessary. Note that Figure 7 is a diagram showing an example of a procedure for the base station 100 and the repeater 200 to establish an RRC connection. Note that Figure 7 shows the process when the repeater 200 is a specific type of repeater (communication device).

[0072] The transmitter 211 of the repeater 200 transmits an RRC setup request message, which is a signal of the RRC layer, to the base station 100 (step S10). Note that the RRC setup request message is transmitted via, for example, SRB0.

[0073] After receiving the RRC setup request message at receiving unit 112, transmitter 111 of base station 100 transmits an RRC setup message, which is an RRC layer signal, to relay 200 (step S20). Note that the RRC setup message includes, for example, information for establishing SRB1. Also, the RRC setup message is transmitted, for example, via SRB0. Also, the RRC setup message is an example of a first signal.

[0074] When the control unit 220 of the repeater 200 receives the RRC setup message at the receiving unit 212, it establishes SRB1 according to the information for establishing SRB1 and transitions the RRC state from the IDLE state to the CONNECTED state (step S30). Note that although it has been described that the RRC state transitions from the IDLE state to the CONNECTED state, this means a state in which a C-RNTI (Cell Radio Network Temporary Identifier) ​​can be acquired. Therefore, transitioning the RRC state from the IDLE state to the CONNECTED state can be rephrased as transitioning from a state in which a C-RNTI cannot be acquired to a state in which a C-RNTI can be acquired, or a state in which a C-RNTI has been acquired. Furthermore, transitioning the RRC state from the IDLE state to the CONNECTED state may also be described as transitioning from a first state to a second state. In step S30, the relay device 200 may maintain the IDLE state without transitioning the RRC state from the IDLE state to the CONNECTED state.

[0075] After step S30, the transmitter 211 of the repeater 200 transmits an RRC setup complete message, which is an RRC layer signal (step S41). The RRC setup complete message includes information indicating that the repeater is a repeater. In other words, the RRC setup complete message includes information indicating a specific type (e.g., NC repeater). The RRC setup complete message is transmitted, for example, via SRB1. A NAS message may be piggybacked on the RRC setup complete message. The piggybacked NAS message may then be used to identify / authorize the repeater 200 in an upper network (core network). The piggybacked NAS message may also include information indicating that the repeater is a specific type of repeater (communication device). The information indicating that the repeater is a specific type of repeater (communication device) is an example of type information.

[0076] Furthermore, whether or not the RRC setup complete message is of a specific type (e.g., NC repeater) may be indicated depending on the bearer used when transmitting the RRC setup complete message. For example, when the RRC setup complete message is transmitted using SRB0, it may be indicated that the message is of a specific type (e.g., NC repeater), and when the RRC setup complete message is transmitted using SRB1, it may be indicated that the message is not of a specific type (e.g., NC repeater).

[0077] When base station 100 receives the RRC setup complete message and the message contains information indicating that the message is an NC repeater, base station 100 recognizes that repeater 200 is a specific type and does not transmit the security mode command message that was transmitted in Fig. 6. The security mode command message is an example of a second signal.

[0078] By processing in this manner, the base station 100 can recognize that the repeater 200 is a specific type of repeater (communication device), thereby reducing the number of signals required to set up or re-set up an RRC connection between the base station 100 and the repeater 200, which is a specific type of repeater (communication device).

[0079] The reason why the security mode command message and subsequent messages do not need to be transmitted to relay 200 (hereinafter referred to as relay 200), which is a specific type of relay (communication device), will be explained. When relay 200 is a specific type of relay (communication device), it is considered that U-palon data will not be transmitted from base station 100 or terminal 300 to relay 200. Therefore, if there is an SRB (e.g., SRB1), which is a bearer for exchanging C-Plane signals, base station 100 can recognize relay 200. Furthermore, signals for controlling relay 200 from base station 100 can be transmitted, for example, by using MAC CE, which does not require security processing. Furthermore, signals transmitted from relay 200 to base station 100 can also be transmitted, for example, by using MAC CE. In this way, since there is no need to process C-Plane and U-Plane signals that require security processing, processing after the security mode command message can be omitted.

[0080] The signals or messages transmitted between step S10 and step S41 in FIG. 7 may be simply referred to as RRC layer signals or RRC layer messages.

[0081] Furthermore, information to be transmitted in the RRC layer signal to the relay 200, which is a specific type of relay (communication device), may be defined in advance in a specification. By defining the information in this way, it becomes unnecessary to transmit, for example, RRC configuration information transmitted after a security message, thereby saving radio resources.

[0082] 8 shows the process up to when base station 100 identifies the type of repeater 200. If the repeater (communication device) is not of a specific type, for example, the process from step S40 onwards shown in FIG.

[0083] When the base station 100 receives the RRC setup complete message (S42), it determines whether the source of the message is a specific type of relay (communication device) (S43). Note that step S43 may be rephrased as determining whether the destination of the RRC setup message is a specific type of relay (communication device). Note that receiving the RRC setup complete message corresponds to, for example, step S40 in FIG. 6 or step S41 in FIG. 7.

[0084] If the base station 100 determines that the sender of the RRC setup complete message is a specific type of repeater (communication device) (Yes in step S43), it controls so as not to send a security mode command message (step S44).

[0085] Furthermore, when base station 100 determines that the source of the RRC setup complete message is not a specific type of repeater (communication device) (No in step S43), it controls to transmit a security mode command message (step S45). Note that step S45 corresponds to step S50 in FIG. 6.

[0086] By performing the above processing, base station 100 can control the transmission of security mode command messages depending on whether the terminal 300 is a specific type of repeater (communication device). Note that base station 100 may also operate by regarding both terminal 300 and repeater 200 as terminals. In this case, base station 100 determines in step S43 whether the terminal is a specific type of terminal (specific type of repeater 200), and performs the processing of step S44 or step S45 depending on the determination result, thereby enabling the processing of FIG. 8 to be used as is. Therefore, a specific type of repeater (communication device) can also be described as a specific type of communication device.

[0087] Note that the method for determining whether the transmission source is a specific type of relay (communication device) or the method for relay 200 notifying base station 100 of information indicating that the transmission source is a specific type of relay (communication device) may be the same as described in embodiment 1, as long as it is consistent. That is, during the random access procedure performed before step S10, relay 200 may notify base station 100 of information indicating that the transmission source is a specific type of relay station (communication device) by transmitting a specific preamble to base station 100. Also, in step S10, notification may be made by including information indicating that the transmission source is a specific type of relay station (communication device) in the RRC setup request message. When including information indicating that the transmission source is a specific type of relay station (communication device) in the RRC setup request message, an Establishment Cause parameter or the most significant N bits of 5G-S-TMSI may be used. In addition, when using the Establishment Cause parameter or the upper N bits of 5G-S-TMSI, the method described in the first embodiment can be used.

[0088] Furthermore, the control information (Side Control Information) transmitted from base station 100 to repeater 200 can use the method described in the first embodiment.

[0089] FIG. 9 shows a first example of the method of the second embodiment reflected in the specification (TS38.331 (Non-Patent Document 28)). As shown in FIG. 9, the NC repeater can be defined in the specification by including a description of the NC repeater in 5.3.1.1 RRC Connection Control. Note that the NC repeater is an example of a specific type of repeater (communication device).

[0090] 10 shows a second example of the method of the second embodiment reflected in the specification (TS38.331 (Non-Patent Document 28)). As shown in FIG. 10, by including a description of NC repeater in 5.3.4.2 Initial AS security activation, it is possible to define it in the specification.

[0091] Note that the second embodiment may be combined as appropriate to the extent that there is no contradiction with the contents of the first embodiment. For example, the method of determining whether the source is a specific type of repeater (communication device) may be the same as that described in the first embodiment.

[0092] Furthermore, the repeater 200 and the terminal 300 may be collectively referred to as a communication device. This is because the base station 100 may collectively regard the repeater 200 and the terminal 300 as a terminal, and therefore the repeater 200 and the terminal 300 may be collectively referred to as a communication device. Even in this case, the operation of FIG. 8 can be performed depending on whether or not the repeater 200 and the terminal 300 are a specific communication device. For example, in the case of the terminal 300, the result of step S43 of FIG. 8 is No.

[0093] As described above, in the second embodiment, after base station 100 transmits an RRC setup message, it controls whether to transmit a security mode command message depending on whether the source of the RRC setup complete message is a specific type of relay (communication device). In other words, after receiving an RRC setup complete message, it controls whether to transmit a security mode command message depending on whether the source of the RRC setup complete message is a specific type of relay (communication device). By controlling in this manner, it is possible to reduce the number of signals to be transmitted when establishing an RRC connection with a specific type of relay (communication device), thereby enabling effective use of network resources.

[0094] Specifically, the number of signals transmitted in Fig. 6 is 7, whereas the number of signals transmitted in Fig. 7, which shows the processing of a specific type of repeater (communication device), is 3. Therefore, it can be seen that the number of signals transmitted is suppressed when a specific type of repeater (communication device) and base station 100 establish an RRC connection. Embodiment 3

[0095] In the first embodiment, an example was described in which whether or not to transmit a second signal is controlled depending on whether the destination of a first signal transmitted by the base station 100 is a specific type of repeater (communication device). Also, in the second embodiment, an example was described in which, when establishing an RRC connection, the base station 100 transmits an RRC setup request message, then receives an RRC setup request complete message corresponding to the RRC setup request message, and controls whether or not to transmit a security mode command message depending on whether the source of the RRC setup request message is a specific type of repeater (communication device). In the third embodiment, an example is described in which the repeater 200 is controlled not to transmit an RRC setup request complete message. In the third embodiment, the wireless communication system, base station, repeater, and terminal are similar to those in the first and third embodiments, and therefore description thereof will be omitted.

[0096] Using Figure 11, we will explain the process until the base station 100 and the repeater 200 establish an RRC connection. Note that the same reference numerals are assigned to the same contents as in Figures 6 and 7. However, the information contained in the signal may change as necessary. Note that Figure 11 is a diagram showing an example of a procedure by which the base station 100 and the repeater 200 establish an RRC connection. Note that the repeater 200 and the terminal 300 may be collectively referred to as a communication device. Figure 11 shows the process when the repeater 200 is a specific type of repeater (communication device).

[0097] The transmitter 211 of the repeater 200 transmits an RRC setup request message, which is a signal of the RRC layer, to the base station 100 (step S10). Note that the RRC setup request message is transmitted via, for example, SRB0.

[0098] After receiving the RRC setup request message at the receiving unit 112, the transmitting unit 111 of the base station 100 transmits an RRC setup message, which is an RRC layer signal, to the relay 200 (step S20). The RRC setup message is transmitted, for example, via SRB0. If the base station 100 determines that the relay 200 is a specific type of relay (communication device), the RRC setup request message does not need to include configuration information for SRB1. Before transmitting the RRC setup request message, the relay 200 can identify the specific type of relay (communication device) by, for example, transmitting a specific random access preamble from among multiple random access preambles during random access, thereby notifying the base station 100 that it is a specific type of relay (communication device). Alternatively, the relay 200 may notify the base station 100 by using UCI or an uplink MAC CE.

[0099] When the control unit 220 of the repeater 200 receives the RRC setup message at the receiving unit 212, the control unit 220 transitions the RRC state from the IDLE state to the CONNECTED state (step S31). Note that although it has been described that the RRC state transitions from the IDLE state to the CONNECTED state, this means a state in which a C-RNTI can be acquired or a C-RNTI has been acquired. Therefore, transitioning the RRC state from the IDLE state to the CONNECTED state can be rephrased as transitioning from a state in which a C-RNTI cannot be acquired to a state in which a C-RNTI can be acquired or a C-RNTI has been acquired. Also, in step S31, the repeater 200 may maintain the IDLE state without transitioning the RRC state from the IDLE state to the CONNECTED state.

[0100] If it is unclear whether the relay 200 is a specific type of relay (communication device) when transmitting the RRC setup message, for example, a timer is started after transmitting the RRC setup message, and a determination is made based on whether a response message to the RRC setup message is received before a predetermined period of time has elapsed. If the terminal 300 fails to receive the RRC setup message, a process such as transmitting the RRC setup message again is performed. Therefore, by considering the RRC setup message transmitted again as a response message to the RRC setup message, it is possible to determine whether the relay 200 is a specific type of relay (communication device) based on whether a response message is received.

[0101] Furthermore, after the establishment of the RRC connection, the relay 200 may notify the base station 100 that it is a specific type of relay (communication device) by using the MAC CE or UCI. In short, after the relay 200 can acquire the C-RNTI in step S31 or transitions to a state in which the relay 200 has acquired the C-RNTI, the relay 200 notifies the base station 100 that it is a specific type of relay (communication device) by using a signal of a layer different from the RRC layer (for example, a physical layer or a MAC layer). By notifying the base station 100 in this manner, the base station 100 can identify that the relay 200 is a specific type of relay (communication device) without receiving an RRC setup complete message.

[0102] The determination of whether the destination of the RRC setup message is a specific type of relay (communication device) may be made using the method described in embodiment 1. That is, in step S10, notification may be made by including information indicating that the destination is a specific type of relay station (communication device) in the RRC setup request message. When including information indicating that the destination is a specific type of relay station (communication device) in the RRC setup request message, the Establishment Cause parameter may be used, or the most significant N bits of 5G-S-TMSI may be used. When using the Establishment Cause parameter or the most significant N bits of 5G-S-TMSI, the method described in embodiment 1 may be used.

[0103] Furthermore, the control information (Side Control Information) transmitted from base station 100 to repeater 200 can use the method described in the first embodiment.

[0104] Note that the third embodiment may be appropriately combined with the first or second embodiment within a range that does not contradict the contents of the first or second embodiment. For example, the method of determining whether the destination of the RRC setup message is a specific type of relay (communication device) may be the method described in the first embodiment.

[0105] Furthermore, repeater 200 and terminal 300 may be collectively referred to as a communication device. This is because base station 100 may collectively regard repeater 200 and terminal 300 as a terminal, and therefore repeater 200 and terminal 300 may be collectively referred to as a communication device.

[0106] As described above, in the third embodiment, after base station 100 transmits the RRC setup message, if the relay is a specific type of relay (communication device), relay 200 does not transmit the RRC setup complete message. By controlling in this manner, base station 100 does not receive the RRC setup complete message, and therefore does not transmit or receive signals from step S40 onward in FIG. 6 . In other words, base station 100 controls not to transmit a security mode command message after transmitting the RRC setup message. By controlling in this manner, the number of signals to be transmitted can be reduced when establishing an RRC connection with a specific type of relay (communication device), thereby enabling effective use of network resources. Embodiment 4

[0107] In the first embodiment, an example was described in which whether or not to transmit a second signal is controlled depending on whether the destination of a first signal transmitted by the base station 100 is a specific type of repeater (communication device). Also, in the second embodiment, an example was described in which, when establishing an RRC connection, the base station 100 transmits an RRC setup request message, receives an RRC setup request complete message corresponding to the RRC setup request message, and controls whether or not to transmit a security mode command message depending on whether the source of the RRC setup request message is a specific type of repeater (communication device). In the third embodiment, an example was described in which the repeater 200 is controlled not to transmit an RRC setup request complete message. In the fourth embodiment, an example is described in which a security mode command message is transmitted and security settings are performed in the repeater 200. In the fourth embodiment, the wireless communication system, the base station, the repeater, and the terminal are the same as those in the first to third embodiments, and therefore description thereof will be omitted. The repeater 200 and the terminal 300 may be collectively referred to as a communication device.

[0108] A process until the base station 100 and the relay 200 establish an RRC connection in the fourth embodiment will be described using Fig. 12. Fig. 12 is a diagram showing an example of a procedure for the base station 100 and the relay 200 to establish an RRC connection. Fig. 12 shows the process when the relay 200 is a specific type of relay (communication device).

[0109] The transmitter 211 of the repeater 200 transmits an RRC setup request message, which is a signal of the RRC layer, to the base station 100 (step S10). Note that the RRC setup request message is transmitted via, for example, SRB0.

[0110] After receiving the RRC setup request message at receiving unit 112, transmitter 111 of base station 100 transmits an RRC setup message, which is an RRC layer signal, to relay 200 (step S20). Note that the RRC setup message includes, for example, information for establishing SRB1. Also, the RRC setup message is transmitted, for example, via SRB0.

[0111] When the control unit 220 of the repeater 200 receives the RRC setup message at the receiving unit 212, it establishes SRB1 according to the information for establishing SRB1, and transitions the RRC state from the IDLE state to the CONNECTED state (step S30). This means a state in which a C-RNTI can be acquired or a C-RNTI has been acquired. Therefore, transitioning the RRC state from the IDLE state to the CONNECTED state can be rephrased as transitioning from a state in which a C-RNTI cannot be acquired to a state in which a C-RNTI can be acquired or a C-RNTI has been acquired.

[0112] After step S30, transmitter 211 of relay device 200 transmits an RRC setup complete message, which is a signal of the RRC layer (step S40). Note that the RRC setup complete message is transmitted, for example, via SRB1. Also, the RRC setup complete message is an example of a first signal.

[0113] After step S40, the transmitter 111 of the base station 100 transmits a security mode command message, which is a signal of the RRC layer, to the terminal 300 (step S50). The security mode command message includes, for example, a security algorithm. The security mode command message is transmitted, for example, via SRB1.

[0114] After step S50, the transmitter 211 of the relay 200 transmits a security mode complete message, which is an RRC layer signal (step S61), and the control unit 220 of the relay 200 activates AS security (step S70). Note that the order of steps S61 and S70 may be reversed, or they may be performed at the same time. Note that the security mode complete message is transmitted, for example, via SRB1. Note that the security mode complete message may include information indicating that the relay 200 is a specific type of relay (communication device). Note that the RRC setup message and the security mode command message are examples of a first signal.

[0115] Although not shown, after transmitting unit 211 of repeater 200 transmits the security mode complete message, a process for notifying UE capability from repeater 200 to base station 100 may be executed. Instead of including information indicating that repeater 200 is a specific type of repeater (communication device) in the security mode complete message, information indicating that repeater 200 is a specific type of repeater (communication device) may be transmitted from repeater 200 to base station 100 using a process for notifying UE capability.

[0116] In addition, instead of including information indicating that the repeater 200 is a specific type of repeater (communication device) in the security mode complete message, the information may be included in the RRC setup complete message and transmitted, as in embodiment 2.

[0117] When the control unit 120 of the base station 100 recognizes that the relay 200 is a specific type of relay (communication device), the control unit 120 controls the relay 200 not to transmit an RRC reconfiguration message, which is a signal of the RRC layer. The RRC reconfiguration message is an example of a first signal.

[0118] Note that the control unit 120 of the base station 100 may control the relay 200 to transmit an RRC reconfiguration message even when the control unit 120 recognizes that the relay 200 is a specific type of relay (communication device). In this case, for example, the RRC reconfiguration message may be transmitted without including at least one of the SRB2 configuration information and the DRB configuration information. That is, when the control unit 120 of the base station 100 recognizes that the relay 200 is a specific type of relay (communication device), the control unit 120 may control the relay 200 not to establish an SRB2 and a DRB, or a DRB. Furthermore, when the control unit 120 of the base station 100 recognizes that the relay 200 is a specific type of relay (communication device), the control unit 120 may control the relay 200 not to perform other configurations, such as adding an SCell (Secondary Cell) or an SCG (Secondary Cell Group).

[0119] In addition, when an RRC reconfiguration message is transmitted from the transmitting unit 111 of the base station 100, for example, the control unit 220 of the repeater 200 may perform control so as not to transmit an RRC reconfiguration complete message.

[0120] In this way, by reducing the number of messages after security is set or by reducing the information included in the messages, it is possible to use wireless resources efficiently.

[0121] Furthermore, the control information transmitted from base station 100 to repeater 200 (Side control information) can be transmitted using the method described in the first embodiment.

[0122] Note that the fourth embodiment may be appropriately combined with the first to third embodiments to the extent that there is no contradiction. For example, the method described in the first to third embodiments may be used to determine whether the source (or destination) is a specific type of relay (communication device). For example, as described in the third embodiment, if relay 200 does not transmit an RRC setup complete message, base station 100 may transmit a security mode command message to relay 200 after a predetermined time has elapsed since transmitting the RRC setup message. In this case, the security mode command message is transmitted via SRB0, or the RRC setup message includes configuration information of SRB1 and is transmitted via an SRB corresponding to the configuration information of SRB1.

[0123] Furthermore, repeater 200 and terminal 300 may be collectively referred to as a communication device. This is because base station 100 may collectively regard repeater 200 and terminal 300 as a terminal, and therefore repeater 200 and terminal 300 may be collectively referred to as a communication device.

[0124] As described above, in the fourth embodiment, after base station 100 transmits an RRC setup message, if the relay is a specific type of relay (communication device), the base station does not transmit an RRC reconfiguration message. Alternatively, after base station 100 transmits an RRC setup message, if the relay is a specific type of relay (communication device), the base station controls the information to be included in the RRC reconfiguration message so as not to include specific information. By controlling in this manner, the number of signals to be transmitted can be reduced when establishing an RRC connection with a specific type of relay (communication device), thereby enabling effective use of network resources. Hardware configuration of each device in each embodiment

[0125] The hardware configuration of each device in the wireless communication system of each embodiment will be described with reference to FIGS.

[0126] Fig. 13 is a diagram showing an example of the hardware configuration of base station 100. As shown in Fig. 13, base station 100 has, as hardware components, for example, an RF (Radio Frequency) circuit 420 equipped with an antenna 410, a CPU (Central Processing Unit) 430, a DSP (Digital Signal Processor) 440, a memory 450, and a network IF (Interface) 460. The CPU is connected via a bus so as to enable input and output of various signals and data signals. The memory 450 includes at least one of a RAM (Random Access Memory) such as an SDRAM (Synchronous Dynamic Random Access Memory), a ROM (Read Only Memory), and a flash memory, and stores programs, control information, and data signals.

[0127] The correspondence between the functional configuration of the base station 100 shown in FIG. 2 and the hardware configuration of the base station 100 shown in FIG. 13 will be described. The transmitter 111 and receiver 112 (or communication unit 110) are realized by, for example, an RF circuit 420, or an antenna 410 and an RF circuit 420. The control unit 120 is realized by, for example, a CPU 430, a DSP 440, a memory 450, a digital electronic circuit (not shown), etc. Examples of digital electronic circuits include an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programming Gate Array), and an LSI (Large Scale Integration). The storage unit 130 is realized by, for example, the memory 450. The communication unit 140 is realized by, for example, a network IF 460.

[0128] It should be noted that base station 100 may generate a plurality of data signals to be transmitted in a plurality of subbands, and the filters that generate these signals may be configured independently for each subband.

[0129] Fig. 14 is a diagram showing an example of the hardware configuration of repeater 200. As shown in Fig. 14, repeater 200 has, as hardware components, an RF circuit 520 including, for example, an antenna 510, a CPU 530, a DSP 540, and a memory 540. Memory 540 includes at least one of a RAM such as an SDRAM, a ROM, and a flash memory, and stores programs, control information, and data signals.

[0130] The correspondence between the functional configuration of repeater 200 shown in Fig. 3 and the hardware configuration of repeater 200 shown in Fig. 14 will be described. Transmitter 211 and receiver 212 (or communication unit 210) are realized, for example, by RF circuit 520, or antenna 510 and RF circuit 520. Controller 220 is realized, for example, by CPU 530, DSP 540, memory 550, and digital electronic circuits (not shown). Examples of digital electronic circuits include ASIC, FPGA, and LSI. Storage unit 230 is realized, for example, by memory 550.

[0131] Fig. 15 is a diagram showing an example of the hardware configuration of terminal 300. As shown in Fig. 15, terminal 300 has, as hardware components, an RF circuit 620 including an antenna 610, a CPU 630, and a memory 640. Terminal 300 may further have a display device such as an LCD (Liquid Crystal Display) connected to CPU 630. Memory 640 includes at least one of a RAM such as an SDRAM, a ROM, and a flash memory, and stores programs, control information, and data signals.

[0132] The correspondence between the functional configuration of the terminal 300 shown in Fig. 4 and the hardware configuration of the terminal 300 shown in Fig. 15 will be described. The transmitter 311 and receiver 312 (or communication unit 310) are realized by, for example, an RF circuit 620, or an antenna 610 and an RF circuit 620. The control unit 320 is realized by, for example, a CPU 630, a memory 640, a digital electronic circuit (not shown), etc. Examples of the digital electronic circuit include an ASIC, an FPGA, and an LSI. The storage unit 330 is realized by, for example, the memory 640.

[0133] In each embodiment, examples of a base station, a terminal, and a repeater are described, but the disclosed technology is not limited to these and can be applied to various devices, such as electronic devices mounted on automobiles, trains, airplanes, artificial satellites, etc., electronic devices transported by drones, etc., robots, AV equipment, home appliances, office equipment, vending machines, and other household equipment.

[0134] Furthermore, although the embodiments have been described using fifth-generation mobile communications as an example, the application of the disclosed technology is not limited to this. For example, the disclosed technology may be applied to mobile communications of different generations, such as sixth and seventh generations.

[0135] 1 Wireless communication system 100 Base station C10 Cell 110 Wireless communication unit 111 Transmitter 112 Receiver 120 Control unit 130 Memory unit 140 Communication unit 200 Repeater C20 Cell 210 Communication unit 211 Transmitter 212 Receiver 220 Control unit 230 Memory unit 300 300A 300B Terminal 310 Communication unit 311 Transmitter 312 Receiver 320 Control unit 330 Memory unit 410 Antenna 420 RF circuit 430 CPU 440 DSP 450 Memory 460 Network IF 510 Antenna 520 RF circuit 530 CPU 540 DSP 550 Memory 610 Antenna 620 RF circuit 630 CPU 640 Memory

Claims

1. A transmitter capable of transmitting a first signal of a Radio Resource Control (RRC) layer to a communication device; a control unit that performs control so as to determine whether or not to transmit a second signal of the RRC layer to the communication device after the first signal, depending on whether the communication device is of a specific type; A base station comprising:

2. When the control unit determines that the communication device is of a first type, the control unit controls the communication device to transmit the second signal.

2. The base station according to claim 1 .

3. The control unit controls the communication device not to transmit the second signal when the communication device is determined to be of a second type.

2. The base station according to claim 1 .

4. a receiving unit configured to receive a third signal including type information indicating whether the communication device is of the second type from the communication device, The control unit controls whether to transmit the second signal in accordance with the type information.

4. The base station according to claim 3 .

5. The type information is information included in MAC CE included in the third signal or information included in uplink control information.

5. The base station according to claim 4.

6. the first signal is a security mode command message; The second signal is an RRC reconfiguration message including an SCell addition configuration, the third signal is an RRC setup complete message; 5. The base station according to claim 4.

7. the first signal is an RRC setup message; the second signal is a security command message; The third signal is an RRC setup complete message.

5. The base station according to claim 4.

8. The control unit determines whether the communication device is of a particular type depending on a bearer over which the third signal is transmitted.

5. The base station according to claim 4.

9. the first signal is an RRC setup message; the second signal is a security command message.

2. The base station according to claim 1 .

10. The control unit determines that the communication device is of a second type when a response signal to the first signal is not received from the communication device.

2. The base station according to claim 1 .

11. The control unit, when determining that the communication device is a second type, controls to transmit a fourth signal of the RRC layer to the communication device; The fourth signal is an RRC reconfiguration message that does not include an SCell addition configuration.

2. The base station according to claim 1 .

12. In a communication device that relays communication between a base station and a terminal, A control unit that controls a configuration of an RRC (Radio Resource Control) connection established between the base station and the mobile station; a receiving unit that receives a first signal of an RRC layer and a second signal of the RRC layer transmitted from the base station when the base station determines that the communication device is a first type, and receives the first signal transmitted from the base station when the base station determines that the communication device is a second type; A repeater comprising:

13. The control unit performs control so as not to configure at least one of an SRB (Signaling Radio Bearer) 2 and a DRB (Data Radio Bearer) when configuring the RRC connection.

13. The repeater according to claim 12.

14. In a terminal that receives a signal transmitted from a base station via a repeater, A receiver that receives a first signal of a Radio Resource Control (RRC) layer and a second signal of the RRC layer transmitted from the base station when the base station determines that the repeater is a first type, and receives the signal transmitted from the base station from the repeater that controls reception of the first signal transmitted from the base station when the base station determines that the repeater is a second type; A control unit that performs signal processing on the received signal; A terminal comprising:

15. A base station; A terminal, A relay device is provided for relaying communication between the base station and the terminal, The base station, According to whether the repeater is a specific type, a control is performed to determine whether to transmit a second signal of the RRC layer to the repeater after transmitting a first signal of the RRC layer to the repeater.

1. A wireless communication system comprising: