Terminal device, control method, and program in wireless communication system using relay device as extension antenna for terminal device

Abstract

To allow a terminal device to communicate with a base station device by using a relay device having an RF relay function as an extended antenna.SOLUTION: A terminal device connected to a base station device determines the need to change the capability information notified to the base station device, and transmits a signal to the base station device for transmitting the capability information to the base station device, and notifies the base station device of the changed capability information while maintaining the connection with the base station device and without receiving an inquiry about capability information from the base station device upon determining that the capability information needs to be changed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a wireless communication system in which a relay device is used as an extension antenna for a terminal device. [Background technology]

[0002] As a technology for the sixth generation cellular communication system, a technology is being considered in which a relay device having a radio frequency (RF) relay function is used as an extended antenna capable of beamforming (see Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] K. Yamazaki, T. Ohseki, Y. Amano, H. Shinbo, T. Murakami, and Y. Kishi, “Proposal for a User-Centric Ran Architecture Towards Beyond 5G”, 2021 ITU Kaleidoscope: Connecting Physical and Virtual Worlds (ITU K), February 2021. Summary of the Invention [Problem to be solved by the invention]

[0004] There has been little progress in studying specific methods for using such relay devices as extension antennas in cellular communication systems. [Means for solving the problem]

[0005] The present invention provides a control technique for a terminal device to communicate with a base station device using a relay device having an RF relay function as an extension antenna.

[0006] A terminal device according to one aspect of the present invention is a terminal device that connects to a base station device and has: a determination means for determining the need to change capability information notified to the base station device; a transmission means for transmitting a signal to the base station device for transmitting the capability information to the base station device in response to a determination that the capability information needs to be changed, while maintaining the connection with the base station device and in a state where no inquiry for the capability information has been received from the base station device; and a notification means for notifying the base station device of the changed capability information. [Effects of the Invention]

[0007] According to the present invention, a terminal device can communicate with a base station device by using a relay device having an RF relay function as an extension antenna. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Figure 2] FIG. 10 is a diagram illustrating an example of a processing flow in which a terminal device acquires capability information of a relay device. [Figure 3] 10 is a diagram illustrating an example of a processing flow in which a terminal device actively notifies a base station device of capability information. [Figure 4] 10 is a diagram illustrating an example of a processing flow in which the terminal device identifies detailed states of the transmission path between the terminal device, the base station device, and the relay device. FIG. [Figure 5] 1 is a diagram illustrating an example of a configuration of a relay device that converts the frequency of a signal received from a terminal device into one of a plurality of frequencies. [Figure 6] FIG. 10 is a diagram illustrating an example of a processing flow for controlling a destination of conversion of a frequency of a wireless signal in a relay device. [Figure 7] FIG. 10 is a diagram illustrating an example of a processing flow in which a terminal device detects a relay device that has only a relay function. [Figure 8] FIG. 2 illustrates an example of the hardware configuration of a terminal device and a relay device. [Figure 9]FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal device. [Figure 10] FIG. 2 illustrates an example of a functional configuration of a part of a relay device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. Furthermore, the same reference numerals are used to designate identical or similar components, and redundant descriptions will be omitted.

[0010] (System Configuration) Fig. 1 shows an example of the configuration of a wireless communication system according to this embodiment. In this wireless communication system, a terminal device 101 is connected to multiple relay devices 121 and 122, and the relay devices 121 and 122 relay communication between the terminal device 101 and a base station device 151. The terminal device 101 and the base station device 151 are wireless communication devices that comply with the 5th generation (5G) or later cellular communication standard of the 3rd Generation Partnership Project (3GPP (registered trademark)), for example. Note that Fig. 1 shows an example in which there is one terminal device 101 and one base station device 151, but it is naturally assumed that there are many of these communication devices.

[0011] In this embodiment, the relay devices 121 and 122 are connected to the terminal device 101 and relay only communications involving the terminal device 101, thereby functioning as pseudo antennas extended from the terminal device 101. That is, the relay devices 121 and 122 function as extended antennas (extension antennas) of the terminal device 101, and are configured to use wireless communication rather than cable between them and the terminal device 101. As a result, the terminal device 101 communicates with the base station device 151 using the relay devices 121 and 122 as antennas provided therein. Note that the base station device 151 does not recognize the relay devices 121 and 122 individually. That is, the terminal device 101 and the relay devices 121 and 122 are combined and operate as a virtual terminal device. In the following, since the relay devices 121 and 122 function as antennas of a virtual terminal device, these devices may be referred to as virtual antennas. To be more precise, each of one or more antennas possessed by the relay devices 121 and 122 is used as a virtual antenna, but when there is no need to particularly distinguish between them, the relay devices 121 and 122 that perform relay transmission may be called a virtual antenna (it may be said that the relay devices 121 and 122 function as virtual antennas). The relay devices 121 and 122 are configured to relay only communications involving the terminal device 101, and do not relay communications of other terminal devices. The relay devices 121 and 122 may be, for example, wireless devices held by users, such as smart watches, but are not particularly limited thereto.

[0012] The relay devices 121 and 122 amplify a radio signal transmitted from the terminal device 101 and relay it to the base station device 151, and also amplify a radio signal transmitted from the base station device 151 and relay it to the terminal device 101. Note that the relay devices 121 and 122 do not demodulate or decode the radio signal transmitted between the terminal device 101 and the base station device 151. That is, the relay devices 121 and 122 have a radio frequency (RF) relay function (function as a wireless repeater). Here, a signal 111 transmitted and received between the terminal device 101 and the relay devices 121 and 122 is transmitted over a short-distance communication line using a high frequency band (terahertz (THz) band) such as the 300 GHz band. On the other hand, a signal 141 transmitted and received between the relay devices 121 and 122 and the base station device 151 is transmitted over a relatively long-distance communication line using a relatively low frequency band (millimeter wave band) such as the 39 GHz band. That is, the relay devices 121 and 122 convert signals received in a first frequency band (THz band) for communication with the terminal device 101 into a second frequency band (millimeter wave band) for communication with the base station device 151 and relay the converted signals, and also convert signals received in the second frequency band into the first frequency band and relay the converted signals.

[0013] Note that the relay devices 121 and 122, as wireless repeaters, only perform amplification and frequency conversion for communications between the terminal device 101 and the base station device 151, but also have a communication function for accepting control from the terminal device 101. Note that in this embodiment, the relay devices 121 and 122 function as wireless repeaters. However, the following discussion may also apply, as necessary, to a case where the relay devices 121 and 122 are configured to perform regenerative relay. As shown in FIG. 1 , for example, the relay devices 121 and 122 each have a communication function unit 131, which is a communication function for accepting control from the terminal device 101, and a relay function unit 132. The communication function unit 131 has a function for performing sidelink communication with the terminal device 101 in accordance with the 3GPP cellular communication standard. Note that this is just an example, and the communication function unit 131 may be configured to communicate with the terminal device 101 via a communication function such as a wireless local area network (LAN) or Bluetooth (registered trademark). The terminal device 101 discovers the relay devices 121 and 122 with which it communicates using the communication function unit 131, for example, using a side link communication function, and connects to the relay devices 121 and 122 through communication with the communication function unit 131.

[0014] The relay function unit 132 has a wireless repeater function of amplifying and frequency-converting a signal received from the terminal device 101 or the base station device 151 and outputting the amplified and frequency-converted signal. The relay function unit 132 may operate in a frequency band different from that of the communication function unit 131. For example, the terminal device 101 may be configured to perform communication for controlling the relay devices 121 and 122 in a relatively low predetermined frequency band, and to perform communication with the base station device 151 via the relay devices 121 and 122 in a high frequency band such as the THz band or millimeter wave band. This is just an example, and the communication function unit 131 may also use a frequency band used by the relay function unit 132, such as the THz band or millimeter wave band. The communication function unit 131 and the relay function unit 132 are each configured to operate in a frequency band corresponding to the operation of the terminal device 101. The terminal device 101 performs only control communication with the relay devices 121 and 122. In addition, by using relay devices 121 and 122 that are located at a short distance from the terminal device 101, the terminal device 101 does not need to transmit signals to the base station device 151 at high power, thereby reducing power consumption.

[0015] In the following, assuming that such a system configuration is used, we will explain the various information to be transmitted and received between the terminal device 101, relay devices 121 and 122, and base station device 151 in this embodiment, and the various processes to be performed.

[0016] (Obtaining capability information about the wireless repeater part of the relay device) As described above, the terminal device 101 can perform control communication to control the relay devices 121 and 122. To do so, the terminal device 101 needs to recognize the capabilities of the relay devices 121 and 122. In particular, it is important for the terminal device 101 to recognize the relay communication function of the relay function unit 132 for communication with the base station device 151. In this embodiment, in consideration of such circumstances, the relay devices 121 and 122 notify the terminal device 101 of capability information regarding the relay function unit 132 using the communication function unit 131. For example, the relay devices 121 and 122 transmit, as capability information, information indicating whether or not they have the relay function unit 132 to the terminal device 101. Furthermore, the relay devices 121 and 122 may transmit, as capability information, information indicating whether or not the relay function unit 132 can function as a virtual antenna for the terminal device 101 to the terminal device 101. By acquiring this information, the terminal device 101 can search for relay devices that can be used as virtual antennas.

[0017] Furthermore, the relay devices 121 and 122 may notify the terminal device 101 of, for example, information indicating a frequency band usable on the terminal device 101 side as capability information. That is, the relay devices 121 and 122 may notify the terminal device 101, as wireless repeaters, of information on a first frequency band (e.g., the THz band) to which a radio signal transmitted from the base station device 151 is converted when relaying the signal to the terminal device 101. The terminal device 101 may determine that the relay devices 121 and 122 are usable as virtual antennas, on the condition that the frequency band usable by the relay devices 121 and 122 matches the frequency band usable by the relay devices 121 and 122. Furthermore, the relay devices 121 and 122 may notify the terminal device 101 of, for example, information indicating a second frequency band (e.g., the millimeter wave band) usable for transmitting and receiving signals to and from the base station device 151 as capability information. For example, the terminal device 101 may determine that the relay devices 121 and 122 can be used as virtual antennas on the condition that the frequency bands available to the base station device 151 match the frequency bands available to the relay devices 121 and 122 on the base station device 151 side. These frequency bands may be notified to the terminal device 101 as a list of frequency bands available to the relay function unit 132, for example. The terminal device 101 can identify the frequency bands to be used in communication performed by the relay devices 121 and 122 by acquiring information on the frequency bands supported by the relay function units 132 of the relay devices 121 and 122. The relay devices 121 and 122 may notify the terminal device 101 of information on at least one of the first frequency band and the second frequency band. In other words, the relay devices 121 and 122 do not necessarily have to notify the terminal device 101 of information on both the first frequency band and the second frequency band, but may notify the terminal device 101 of only information on either the first frequency band or the second frequency band.

[0018] The relay devices 121 and 122 may also notify the terminal device 101 of information on the number and configuration of physical antennas available in the relay function unit 132 as capability information. The information on the number of antennas may include, for example, information on the number of antennas available on the terminal device 101 side and the number of antennas available on the base station device 151 side. The information on the number of antennas may also include, for example, information indicating the number of antennas corresponding to each frequency band available on the relay devices 121 and 122. The information on the antenna configuration may also include information on the relative positions of the antennas. The information on the antenna configuration may also include information on the number of streams available for transmission and reception to and from the base station device 151. Based on this information, the terminal device 101 may transmit multiple streams to the relay devices 121 and 122, for example, using polarized waves or multiple frequency bands. The relay devices 121 and 122 may separate the multiple streams into polarized waves or frequency bands and transmit these multiple streams in parallel using multiple antennas (and multiple frequency bands, as necessary) on the base station device 151 side. In this way, the terminal device 101 can identify the type of communication that can be performed via the relay devices 121 and 122 based on the information on the number and configuration of antennas.

[0019] 2 shows an example of a processing flow when capability information of the relay devices 121 and 122 is provided to the terminal device 101. For example, the terminal device 101 transmits a message inquiring about capability information to each of the relay devices 121 and 122 (S201), and each of the relay devices 121 and 122 provides its own capability information to the terminal device 101 (S202). The terminal device 101 may transmit an inquiry message including information indicating whether the terminal device 101 is a terminal device that can use a virtual antenna. If the terminal device 101 is able to use a virtual antenna, the relay devices 121 and 122 may notify the terminal device 101 of information indicating whether the terminal device 101 has a function as a virtual antenna. The terminal device 101 may transmit an inquiry message including information about a frequency band (e.g., THz band) that can be used between the terminal device 101 and the relay device that functions as a virtual antenna. The terminal device 101 may transmit an inquiry message including information about a frequency band that the base station device 151 uses for communication. In these cases, the relay devices 121 and 122 may notify the terminal device 101 of information on frequency bands that can be used by the relay devices themselves, or may notify the terminal device 101 of information indicating whether a frequency band included in an inquiry message is usable, as capability information. The terminal device 101 may also transmit an inquiry message that includes information on the number and configuration of antennas that the relay devices 121 and 122 have. As described above, the relay devices 121 and 122 notify the terminal device 101 of information on the number and configuration of antennas that the relay devices themselves have, as capability information.

[0020] The terminal device 101 may acquire capability information about the wireless repeater parts (relay function units 132) from the relay devices 121 and 122, for example, using a provision for sidelink communication in the 3GPP standard. In this case, the communication function units 131 of the relay devices 121 and 122 are configured to operate in accordance with the provision for sidelink communication. In this case, for example, the capability information for sidelink communication can be used. In sidelink communication, a terminal device transmits a UECapabilityEnquirySidelink message inquiring about capability information of another terminal device, and the other terminal device transmits a UECapabilityinformationSidelink message including capability information of its own device. For example, in the above-mentioned S201, the terminal device 101 transmits a first message obtained by extending the UECapabilityEnquirySidelink message to the relay devices 121 and 122. Then, when the communication function unit 131 of the relay devices 121 and 122 receives the message in which the UECapabilityEnquirySidelink message is extended, in the above-mentioned S202, it can transmit capability information regarding the wireless repeater part (relay function unit 132) to the terminal device 101 using the message in which the UECapabilityInformationSidelink message is extended.

[0021] The terminal device 101 may transmit, to the relay devices 121 and 122, information indicating an inquiry about capability information related to the wireless repeater portion in a message that is an extension of the UECapabilityEnquirySidelink message. This message may also include information inquiring about whether the relay devices 121 and 122 have wireless repeater functionality (whether they can operate as virtual antennas). The conventional UECapabilityEnquirySidelink message includes a frequencyBandListFilterSidelink that inquires about frequency bands compatible with sidelink communication and combinations of frequency bands that can be used in sidelink communication. This information includes only information about frequency bands for sidelink communication and does not include information unrelated to sidelink communication, such as wireless repeaters. Therefore, in this embodiment, this information may be extended to enable an inquiry about available frequency bands related to the wireless repeater portion. The terminal device 101 may also transmit, to the relay devices 121 and 122, a ue-CapabilityInformationSidelink that includes its own capability information, similar to the conventional UECapabilityEnquirySidelink message. Note that this is just an example, and capability information does not need to be transmitted from the terminal device 101 to the relay devices 121 and 122. In addition, the extended UECapabilityEnquirySidelink message may include information inquiring about the number and configuration of antennas in the wireless repeater parts of the relay devices 121 and 122.

[0022] The relay devices 121 and 122 notify the terminal device 101 of, for example, information indicating whether they have a function as a wireless repeater, using a message that is an extension of the UECapabilityInformationSidelink message. Furthermore, the relay devices 121 and 122 can notify the terminal device 101 of the supported frequency bands (and combinations of supported frequency bands) of the wireless repeater portion, using information similar to the conventional supportedBandCombinationListSidelink or supportedBandListSidelink. Furthermore, the relay devices 121 and 122 notify the terminal device 101 of the number and configuration of antennas of the wireless repeater portion.

[0023] The relay devices 121 and 122 may notify the terminal device 101 of the capability information described above, regardless of the sidelink communication standard. For example, the capability information may be notified using a Bluetooth (registered trademark) profile. That is, the communication function units 131 of the terminal device 101 and the relay devices 121 and 122 may be configured to perform Bluetooth communication. Then, in step S202 described above, the relay devices 121 and 122 may notify the terminal device 101 of information such as whether they have a virtual antenna function, supported frequency bands, the number and configuration of antennas, etc., using Generic Attribute Profile (GATT). The terminal device 101 may also notify the relay devices 121 and 122 of its own information using GATT. The communication function units 131 of the terminal device 101 and the relay devices 121 and 122 may transmit and receive capability information using a wireless LAN.

[0024] The terminal device 101 identifies, for example, the relay devices 121 and 122 that can operate as virtual antennas from the acquired capability information of the relay devices 121 and 122. Then, the terminal device 101 recognizes the configuration of the virtual antenna based on the frequency bands and the number and configuration of antennas that the relay devices 121 and 122 can use on the base station device 151 side, and can communicate with the base station device 151 using that configuration. Note that the relay devices 121 and 122 may transmit their own capability information without receiving an inquiry message from the terminal device 101. For example, the relay devices 121 and 122 may voluntarily transmit their own capability information in response to, for example, being powered on or receiving a user operation to turn on their function as virtual antennas. By detecting such capability information, the terminal device 101 can recognize the presence of a device that functions as a virtual antenna in the vicinity.

[0025] (Update of terminal device capability information) As described above, the terminal device 101 can communicate with the base station device 151 using the relay devices 121 and 122 as virtual antennas. The terminal device 101 notifies the base station device 151 of capability information, such as the number of antennas, assuming the existence of such virtual antennas. For example, if the relay devices 121 and 122 each have two antennas on the base station device 151 side, the terminal device 101 can be said to virtually have four antennas because the two relay devices each have two antennas. Therefore, in such a case, the terminal device 101 can notify the base station device 151 that it has four antennas as capability information. However, in such an environment, the number of virtual antennas in the terminal device 101 can change, for example, when one of the relay devices 121 and 122 is powered off or when a connection with a new relay device is established.

[0026] Furthermore, for example, when transmitting channel state information (CSI) to the base station device 151, the terminal device 101 can compress the CSI using artificial intelligence (AI) / machine learning (ML). For example, a first trained model for acquiring compressed CSI that can obtain a compression rate determined by a predetermined criterion, such as the lowest compression rate or a compression rate lower than a reference value, is acquired by ML using the uncompressed CSI as input, and a second trained model for acquiring uncompressed CSI by ML using the compressed CSI as input. At this time, the first trained model is stored in the terminal device 101, and the second trained model is stored in the base station device 151. For example, the terminal device 101 may acquire CSI by channel estimation in its own device, perform ML based on the acquired CSI, generate a first trained model and a second trained model, and notify the base station device 151 of the second trained model. This second trained model may be provided from the terminal device 101 to the base station device 151 as, for example, capability information. Note that the capability information may indicate only whether or not CSI compression and decompression are possible using the first trained model and the second trained model, and the second trained model may be notified to the base station device 151 separately from the capability information. As a result, when the terminal device 101 acquires CSI through channel estimation, it compresses the CSI using the first trained model and transmits it to the base station device 151, and the base station device 151 inputs the received compressed CSI to the second trained model to obtain the result of channel estimation in the terminal device 101. On the other hand, for example, if the communication environment between the terminal device 101 and the base station device 151 changes significantly, it is expected that the trained model will no longer be suitable for that communication environment. In this case, the terminal device 101 may update the second trained model notified to the base station device 151 as capability information.

[0027] Furthermore, the terminal device 101 can control the beam to be used in communication between the terminal device 101 and the base station device 151 using AI / ML. For example, the terminal device 101 and the base station device 151 measure wireless quality using only a portion of the many available beams, and use the measurement results as input to perform ML to select an optimal beam from all available beams, thereby generating a trained model. In one example, the base station device 151 transmits measurement signals using all available beams, and the terminal device 101 selects an optimal beam from the measurement results of the signals. At the same time, the terminal device 101 can generate a trained model by ML using the measurement results of signals transmitted using some of the beams as input and the selected optimal beam as training data. At this time, the terminal device 101 can notify the base station device 151, as capability information, that beam selection can be performed using the trained model. Even in this case, if the communication environment between the terminal device 101 and the base station device 151 changes significantly, it is expected that the trained model will no longer be suitable for that communication environment. In this case, it is expected that the terminal device 101 will be unable to perform beam selection using a trained model, even though it has notified the base station device 151 that it is capable of doing so as capability information.

[0028] As described above, it is expected that the capability information of the terminal device 101 will dynamically change when a virtual antenna is used or when AI / ML is used. In contrast, conventionally, the terminal device 101 cannot provide its own capability information to the base station device 151 unless an inquiry is received from the base station device 151. As a result, the base station device 151 may end up communicating with the terminal device 101 according to inaccurate capability information. Here, the base station device 151 acquires the capability information of the terminal device 101 when establishing a connection with the terminal device 101. As a result, the terminal device 101 can disconnect the connection and perform a reconnection process every time the capability information changes. However, in this case, disconnection and reconnection are repeated every time the configuration of the virtual antenna or the communication status in the terminal device 101 changes, which can significantly increase signaling overhead.

[0029] In view of such circumstances, this embodiment enables the terminal device 101 to spontaneously transmit capability information to the base station device 151 while maintaining connection with the base station device 151. An example of the flow of this process is shown in FIGS. 3(A) and 3(B). For example, when the terminal device 101 detects the need to change the capability information (S301), the terminal device 101 decides to transmit the capability information to the base station device 151 (S302). Then, the terminal device 101 spontaneously transmits the capability information to the base station device 151. The terminal device 101 transmits UECapabilityInformation to the base station device 151 without receiving an inquiry message from the base station device 151. Furthermore, the terminal device 101 may, for example, request the base station device 151 to transmit an inquiry message (S311). That is, the terminal device 101 transmits a message requesting transmission of a UECapabilityEnquiry message to the base station device 151. When the terminal device 101 receives a UECapabilityEnquiry transmitted from the base station device 151 in response to this request message (S312), it transmits UECapabilityInformation to the base station device 151 in response to the UECapabilityEnquiry (S313). In this way, in a state where the terminal device 101 has not received an inquiry about capability information from the base station device 151, it transmits a signal for transmitting capability information to the base station device 151. Then, the terminal device 101 notifies the base station device 151 of the changed capability information using this signal, thereby enabling the base station device 151 to control the communication of the terminal device 101 using accurate capability information.

[0030] A message for causing the terminal device 101 to transmit capability information or a capability information inquiry message to the base station device 151 is transmitted using, for example, a radio resource control (RRC) message, a physical uplink control channel (PUCCH), or a medium access control control element (MAC CE). When the terminal device 101 voluntarily transmits capability information, the capability information may include all of the changed capability information of the terminal device 101 transmitted to the base station device 151, or may include only the changed part of the capability information transmitted to the base station device 151. In addition, in a message for causing the base station device 151 to transmit a capability information inquiry message, the terminal device 101 may transmit only a request to transmit the inquiry message, or may transmit, for example, information indicating which item of the capability information will be changed.

[0031] The capability information transmitted from the terminal device 101 to the base station device 151 may include, for example, MIMO (Multiple Input Multiple Output) related information and information on corresponding frequency bands. The MIMO related information includes, for example, sounding reference signal (SRS) configuration information (SRSConfig), beam configuration information (SpatialrelationInfo), and the number of MIMO layers for each of the downlink and uplink (maxNumberMIMOLayersPDSCH, maxNumberMIMO-LayersCBPUSCH). As described above, the capability information may include information necessary to execute the function, such as information on an AI / ML model.

[0032] For example, the terminal device 101 may determine that a change in capability information is necessary in response to a loss of connection with a relay device used as a virtual antenna or when a new connection is made with a relay device used as a virtual antenna. Furthermore, the terminal device 101 may, for example, input CSI into a first trained model for compression, and then input the compressed CSI obtained by inputting the CSI into a second trained model for decompression, and determine whether the original CSI is restored. If the original CSI is not accurately restored (if the error exceeds a predetermined value), the terminal device 101 may determine that a change in capability information (re-learning of the model) is necessary. Furthermore, the terminal device 101 may input measurement results of only a portion of available beams into the trained model and determine whether a beam identified as a beam to be used is an optimal beam among all available beams. That is, the terminal device 101, for example, periodically performs measurements on all available beams and determines whether a beam to be used determined based on the measurement results matches a beam identified using the trained model. Then, when the beams do not match, the terminal device 101 may determine that a change in capability information (re-learning of the model) is necessary. In one example, when model re-learning is necessary, the terminal device 101 may transmit a transmission request for capability information or a capability information inquiry message to the base station device 151 in response to completion of the re-learning. In this way, since a re-learned model exists at the time the message is transmitted, communication using the re-learned model can be performed in a short time.

[0033] Furthermore, the terminal device 101 may transmit a request to transmit capability information or a capability information inquiry message to the base station device 151 in response to determining that model re-learning is necessary. In this case, the base station device 151 can immediately stop using a trained model for decompressing CSI that is no longer suitable for the communication conditions, for example. Note that CSI can be provided from the terminal device 101 to the base station device 151 using conventional procedures until the terminal device 101 updates the trained model and provides it to the base station device 151, and until the base station device 151 receives the updated trained model. This prevents communication control based on inaccurate CSI caused by using an inappropriate trained model. Furthermore, the base station device 151 can transmit measurement signals using all available beams to cause the terminal device 101 to perform re-learning, for example, to update a trained model for beam control that is no longer suitable for the communication conditions.

[0034] (Reporting wireless quality to terminal devices by relay devices) When communication between the terminal device 101 and the base station device 151 is performed using the relay devices 121 and 122 described above, both the wireless quality associated with the first transmission path (e.g., in the THz band) between the terminal device 101 and the relay devices 121 and 122 and the wireless quality associated with the second transmission path (e.g., in the millimeter wave band) between the relay devices 121 and 122 and the base station device 151 affect the communication quality between the terminal device 101 and the base station device 151. For example, it is assumed that a wireless signal transmitted from the base station device 151 is received at low power by the relay devices 121 and 122, and noise due to the relay devices 121 and 122 is added to the wireless signal, resulting in a low signal-to-noise ratio (SNR). When the wireless signal with a low SNR is amplified, not only the signal component but also the noise component are significantly amplified. Therefore, even if the received power of the wireless signal at the terminal device 101 is sufficient, the SNR of the wireless signal remains low. Similarly, if the SNR of a wireless signal transmitted from the terminal device 101 and received at the relay devices 121 and 122 is low, the SNR of the wireless signal will remain low even if the received power of the wireless signal transmitted from the relay devices 121 and 122 and received at the base station device 151 is sufficient. That is, if the power of the signal reaching the relay devices 121 and 122 is low, the SNR will be low due to noise caused by the relay devices 121 and 122, and the wireless signal will be amplified, and the SNR of the wireless signal may remain low even if the received power of the wireless signal at the terminal device 101 and the base station device 151 is sufficient.

[0035] In such a case, it may be assumed that the communication between the terminal device 101 and the base station device 151 cannot transmit and receive radio signals normally, even though the radio quality (received power) at the terminal device 101 appears to be good. In response to this, the terminal device 101 can ensure a sufficiently high communication quality of the communication between the terminal device 101 and the base station device 151 by using, for example, a relay device that can achieve a predetermined quality level in the radio quality of both the first transmission path and the second transmission path as a virtual antenna. Meanwhile, the terminal device 101 and the base station device 151 can recognize the communication quality of the communication via the entire transmission path between the terminal device 101 and the base station device 151 using an existing technique such as channel estimation, but cannot recognize the communication quality that distinguishes between the first transmission path and the second transmission path. For this reason, the terminal device 101 cannot select an appropriate relay device that ensures a sufficiently high communication quality of the communication between the terminal device 101 and the base station device 151.

[0036] In this embodiment, in consideration of the above circumstances, the relay devices 121 and 122 identify the wireless quality of the first transmission path and the wireless quality of the second transmission path in the relay function unit 132 and notify the terminal device 101 of the identification result. For example, the relay function units 132 of the relay devices 121 and 122 measure predetermined signals transmitted from the terminal device 101 and the base station device 151 to measure the wireless qualities of the first transmission path and the second transmission path, respectively. The relay function units 132 then provide the measurement results to the communication function unit 131, which then notifies the terminal device 101 of the provided wireless quality measurement values. Here, the predetermined signal may be, for example, a reference signal or a synchronization signal generated using a known sequence, and the wireless quality may be, for example, the received power of the signal or a signal-to-noise-and-interference ratio (SINR). The relay function unit 132 can measure the wireless quality, for example, by correlation detection using the known sequence used to generate the predetermined signal. Furthermore, the relay function unit 132 may measure the received power of the radio signal using, for example, a power detector connected to antennas on the terminal device 101 side and the base station device 151 side. The power detector may be arranged so as to be accessible by the communication function unit 131. In this case, the relay function unit 132 may not have a correlation detection function or a function of providing information to the communication function unit 131. That is, the relay function unit 132 may be configured only with functions as a radio repeater, such as amplifying the received signal and converting the frequency. Note that at least one of the radio qualities of the first transmission path and the second transmission path may be measured and reported to the terminal device 101. That is, only the radio quality of the first transmission path may be measured and reported, only the radio quality of the second transmission path may be measured and reported, or both may be measured and reported.

[0037] The relay devices 121 and 122 may, for example, periodically measure the radio qualities of the first transmission path and the second transmission path, respectively, or may perform measurements in response to receiving an instruction from the terminal device 101. In one example, the base station device 151 may transmit a predetermined notification to the terminal device 101 when the received power of a signal from the terminal device 101 is sufficient but the quality, such as the SNR, of the signal is insufficient. Then, upon receiving the predetermined notification, the terminal device 101 may transmit an instruction signal to the relay devices 121 and 122 to perform measurements. Similarly, the terminal device 101 may transmit an instruction signal to the relay devices 121 and 122 to perform measurements when the received power of a signal from the base station device 151 is sufficient but the quality, such as the SNR, of the signal is insufficient.

[0038] 4 shows an example of the flow of this process. In this process, the relay devices 121 and 122 measure radio quality, such as the received power of a downlink radio signal transmitted from the base station device 151 (S401, S402), and also measure radio quality, such as the received power of an uplink radio signal transmitted from the terminal device 101 (S403, S404). Note that the relay devices 121 and 122 are connected to the terminal device 101 and function as virtual antennas, so that signals transmitted from the base station device 151 are relayed to the terminal device 101, and signals transmitted from the terminal device 101 are relayed to the base station device 151. The relay devices 121 and 122 notify the terminal device 101 of at least one of the measurement results in S402 and S404 (S405). Note that the notification in S405 can be performed using, for example, sidelink communication, Bluetooth, wireless LAN, or the like. When sidelink communication is used, the notification in step S405 may be performed using a physical sidelink control channel (PSCCH) or a physical sidelink shared channel (PSSCH). The relay devices 121 and 122 may perform measurement and reporting periodically, or may perform measurement and reporting aperiodically in accordance with a measurement instruction (S406) from the terminal device 101. The terminal device 101 may instruct the communication function units 131 of the relay devices 121 and 122 to report when the measurement results satisfy a predetermined condition. In this way, the terminal device 101 can acquire measurement results of the wireless quality of the first transmission path between the relay devices 121 and 122 and the base station device 151, from the relay devices 121 and 122.

[0039] Upon receiving the measurement results of the wireless quality at the relay devices 121 and 122, the terminal device 101 transmits the measurement results to the base station device 151, for example. The base station device 151 may perform transmission power control or the like based on the measurement results. For example, when the wireless quality (e.g., the received power at the relay devices 121 and 122) related to the second transmission path is low, the base station device 151 performs control to increase the transmission power of the downlink signal. Furthermore, when the received measurement results of the wireless quality indicate that the wireless quality related to the first transmission path is low (for example, below a predetermined value), the terminal device 101 may perform control to increase the transmission power of the uplink signal. Furthermore, when the terminal device 101 uses, as a virtual antenna, a relay device whose wireless quality related to at least one of the first transmission path and the second transmission path is insufficient (the wireless quality is below a predetermined value), the terminal device 101 may stop using the relay device. Furthermore, the terminal device 101 may switch the relay device to be used. The terminal device 101 may instruct relay devices that are not being used as virtual antennas to measure and report wireless quality, thereby allowing the terminal device 101 to select a relay device with good wireless quality from among the unused relay devices and use it as a new virtual antenna.

[0040] (Frequency conversion in repeater devices) As described above, the terminal device 101 multiplexes and transmits signals to the relay devices 121 and 122 using polarizations and multiple frequency channels (e.g., in the THz band). The relay devices 121 and 122 then convert the signals into signals of a single frequency channel and relay them to the base station device 151. If the frequency channels converted by the relay devices 121 and 122 are fixed, many terminal devices using virtual antennas will use the frequency channels, making it difficult to secure sufficient resources for the frequency channels. Note that multiple "frequency channels" may be set for one frequency band, or only one may be set for one frequency band. That is, the frequency channel may be a partial band within one frequency band, or the entire frequency band.

[0041] For this reason, in this embodiment, the relay devices 121 and 122 are configured to be able to use multiple different frequency channels included in a frequency band that can be used to relay wireless signals to the base station device 151. Then, the relay devices 121 and 122 set the frequency channels to be used when relaying signals to the base station device 151 in accordance with instructions from the terminal device 101. This prevents communications of many terminal devices that use the relay devices from concentrating on a specific frequency channel, and also improves the flexibility of frequency resource allocation.

[0042] 5 shows an example of the configuration of the relay devices 121 and 122 according to this embodiment. For example, the terminal device 101 transmits radio signals containing separate data on frequency channel A and frequency channel B. Upon receiving the radio signals, the relay devices 121 and 122 separate the radio signals using a band-pass filter (BPF) 502 that passes only the band of frequency channel A and a BPF that passes only the band of frequency channel B. The relay devices 121 and 122 then frequency-convert the frequencies of the radio signals to frequency C or frequency D, for example, using a waveform output by an oscillator 503. The frequency-converted radio signals are supplied to a switch 504 so that they are input to either a BPF 505 for frequency C or a BPF 506 for frequency D. For example, when a radio signal is to be output at frequency C, the switch 504 switches the output destination so that the radio signal is input to the BPF 505 and is not input to the BPF 506. Furthermore, switch 504 switches the output destination so that, for example, when a radio signal is to be output at frequency D, the radio signal is input to BPF 506 and the radio signal is not input to BPF 505. When the frequency of the radio signal to be relayed is frequency C, the radio signal that has passed through BPF 505 is amplified and relayed (output from the antenna), and when the frequency of the radio signal to be relayed is frequency D, the radio signal that has passed through BPF 506 is amplified and relayed (output from the antenna).

[0043] 5 illustrates an example in which two frequency bands (frequencies C and D) can be used to relay radio signals to the base station device 151. However, the relay devices 121 and 122 may be configured to be able to use three or more frequency bands. While the example illustrates an example in which radio signals transmitted from the terminal device 101 to the relay devices 121 and 122 are frequency-multiplexed, they may be multiplexed using polarization or time, for example. In this case, the relay devices 121 and 122 may separate signals transmitted using different polarizations or at different times, and perform radio signal conversion processing so that the signals are transmitted at the same frequency and time using multiple antennas. However, in either case, when the relay function unit 132 operates as a wireless repeater, processing such as signal demodulation, decoding, re-encoding, and re-modulation is not required.

[0044] The relay devices 121 and 122 receive instruction information from, for example, the terminal device 101 using the communication function unit 131. The instruction information includes the changed frequency. Upon receiving the instruction information from the terminal device 101, the communication function unit 131 supplies the instruction content to the control unit 501. Then, in the relay devices 121 and 122, the control unit 501 controls the frequency of the oscillator 503 and the switch 504 so that a radio signal of the specified frequency is output. That is, the control unit 501 controls the oscillation frequency of the oscillator 503 and further sets the output destination of the switch 504 so that the frequency-changed radio signal is input to an appropriate BPF. As described above, the relay devices 121 and 122 notify the terminal device 101 of available frequency bands (frequency channels) as capability information. The terminal device 101 transmits information on the frequency bands indicated as available by the capability information to the base station device 151 as its own capability information. The base station device 151 then selects one of the available frequency bands indicated as the capability information, and allocates frequency resources included in the selected frequency band to the terminal device 101. The terminal device 101 instructs the relay devices 121 and 122 to use the allocated frequency band. The control units 501 of the relay devices 121 and 122 then convert the radio signal arriving from the terminal device 101 into a radio signal of that frequency band and relay it.

[0045] 6 shows an example of the flow of frequency configuration processing of the relay devices 121 and 122. In this processing, first, the relay devices 121 and 122 transmit capability information including frequency bands usable for relaying wireless signals to the base station device 151 to the terminal device 101 (S601). Then, the terminal device 101 notifies the base station device 151 (for example, via the relay devices 121 and 122 or directly without via the relay devices 121 and 122) of the capability information indicating the frequency bands usable by the relay devices 121 and 122 as frequency bands usable by the terminal device 101 (S602). Then, the base station device 151 selects one of the frequency bands indicated in the capability information, allocates resources for uplink communication in that frequency band, and notifies the terminal device 101 of information indicating the allocated resources (for example, via the relay devices 121 and 122 or directly without via the relay devices 121 and 122) (S603). The base station device 151 may notify the terminal device 101 of a combination of information about a frequency band to be used and information indicating which resources in the frequency band are allocated. If the information specifying a frequency resource identifies a frequency band including the frequency resource, the information about the frequency band does not need to be notified to the terminal device 101. The terminal device 101 transmits an instruction to the relay devices 121 and 122 to relay uplink signals to the base station device 151 using the frequency band corresponding to the allocated frequency resource (S604). Then, in accordance with the instruction, the relay devices 121 and 122 control, for example, the oscillator 503 and the switch 504 to perform settings to relay uplink signals to the base station device 151 using the instructed frequency band (S605).

[0046] The base station device 151 may also notify the terminal device 101 of information indicating which frequency band to use in which time slot (time). In this case, the terminal device 101 may similarly notify the relay devices 121 and 122 of information associating time slots with frequency bands to be used, and the control units 501 of the relay devices 121 and 122 may execute control processing to change the frequency bands to be used over time according to the information. This makes it possible to switch the frequency bands to be used at appropriate times, enabling more flexible use of multiple frequency bands. Alternatively, information associating multiple time slots (times) with the corresponding frequency bands to be used may be notified to the relay devices 121 and 122. The relay devices 121 and 122 perform control to use the corresponding frequency bands in each of the multiple time slots. In this way, by notifying information specifying the time change of the frequency bands to be used, the number of times of transmission of instruction signals can be reduced, and the frequency bands to be used can be switched frequently and flexibly. The terminal device 101 may transmit instructions on the frequency bands to be used to the multiple relay devices 121 and 122 individually, or may transmit the instructions to all of them at once by multicasting.

[0047] Thereafter, the terminal device 101 transmits uplink signals using a time and frequency range in the frequency band before conversion by the relay devices 121 and 122, which corresponds to the resources allocated in S603 (e.g., a specific time and frequency range in the frequency band to be used indicated by the resource block). For example, if the lower end of the frequency band (e.g., frequency C or frequency D in FIG. 5) used when relaying wireless signals from the relay devices 121 and 122 to the base station device 151 is set to f2, the lower end of the allocated frequency resource is set to f2+Δ, and the lower end of the frequency band (e.g., frequency A in FIG. 5) used when transmitting wireless signals from the terminal device 101 to the relay devices 121 and 122 is set to f0, the terminal device 101 transmits uplink signals in frequency resources whose lower end is f0+Δ. 5, when transmitting radio signals to the relay devices 121 and 122 using multiple frequency bands, for example, when the lower ends of two frequency bands (for example, frequency A and frequency C in FIG. 5) are f0 and f1, respectively, the terminal device 101 transmits uplink signals in frequency resources whose lower ends are f0+Δ and f1+Δ. In this way, for example, the base station device 151 can flexibly allocate radio resources, and it is possible to avoid congestion in only a specific frequency band.

[0048] (Identification of relay devices with only analog functionality) In the above example, the terminal device 101 uses the sidelink communication function or the like to discover and connect to the relay devices 121 and 122 having the communication function unit 131, and uses the connected relay devices 121 and 122 as virtual antennas. The terminal device 101 determines its own (virtual) capabilities, such as the number of MIMO layers, by recognizing the relay devices that can be used as virtual antennas. Therefore, when using virtual antennas, it is necessary to recognize the relay devices. On the other hand, if the relay devices 121 and 122 only have the relay function unit 132 and do not have the communication function unit 131, the terminal device 101 cannot use the sidelink communication function or the like, and therefore it is assumed that the terminal device 101 cannot discover the relay devices 121 and 122.

[0049] In this embodiment, in consideration of the above circumstances, in order to discover a relay device having only the relay function unit 132, the terminal device 101 transmits at least one of a signal in a first frequency band (e.g., THz band) used when communicating with the base station device 151 using a virtual antenna and a signal in a second frequency band (e.g., millimeter wave band) converted by the relay device, and detects radio waves in the frequency band after frequency conversion (performed when a relay device is present). That is, when a relay device is present nearby, the wireless signal transmitted by the terminal device 101 is frequency-converted by the relay device and output. Therefore, when the terminal device 101 can detect the frequency-converted wireless signal, it can determine that a relay device is present nearby. That is, when the terminal device 101 transmits a signal in the first frequency band and then detects a signal in the second frequency band, or when it transmits a signal in the second frequency band and then detects a signal in the first frequency band, it can determine that a relay device is present nearby.

[0050] The terminal device 101 may periodically transmit at least one of a signal in the first frequency band and a signal in the second frequency band, and perform a process of detecting a signal in the converted frequency band. However, this is not limited to this, and the terminal device 101 may transmit a signal and perform a process of detection when a predetermined event is detected. For example, the terminal device 101 may transmit a signal and perform a process of detection when a user operation on the terminal device 101 instructs the start of detection. For example, the relay device is a device whose presence can be recognized by a user, such as a wireless device held by a user, such as a smartwatch, and it is assumed that the user turns on the switch of the device to instruct the device to start detection.

[0051] Here, it is assumed that the relay device has a constant amplification factor, for example. At this time, the terminal device 101 transmits a signal with sufficiently weak power. As a result, even if a signal transmitted by the terminal device 101 in a first frequency band is amplified by the relay device and output in a second frequency band, it is possible to prevent the signal from interfering strongly with signals from other terminal devices in the base station device 151. Similarly, the terminal device 101 transmits a signal in the second frequency band with sufficiently weak power and detects a signal in the first frequency band. Note that THz band signals are subject to large distance attenuation, and even if amplified and output, the range of their radio waves is limited, so it is expected that they will not interfere with other signals.

[0052] For example, frequency and time resources for searching for relay devices may be prepared in the form of a resource pool. For example, resources from which the terminal device 101 can transmit a search signal and corresponding resources from which the terminal device 101 receives a frequency-converted and relayed signal are set. For example, a THz band frequency and time resource is prepared as a first resource, and a millimeter wave band frequency and time resource corresponding to the first resource is prepared as a second resource. Furthermore, a millimeter wave band frequency and time resource is prepared as a third resource, and a THz band frequency and time resource corresponding to the third resource is prepared as a fourth resource. The terminal device 101 transmits a signal using the first resource or the third resource and determines whether the frequency-converted signal is detected using the second resource or the fourth resource, thereby determining whether a relay device is present. For example, the first resource may be set during a period in which the base station device 151 does not transmit a millimeter wave band signal. For example, the first resource is set in a time slot to which uplink resources are allocated. Note that a second resource corresponding to the first resource may also be set in the same time slot. If a relay device is present, the signal transmitted in the first resource in the THz band is converted by the relay device into a signal in the second resource in the millimeter wave band and relayed. According to the above-described setting, the base station device 151 does not transmit a millimeter wave signal, and therefore the terminal device 101 can measure the millimeter wave signal relayed by the relay device under interference-free conditions. Furthermore, the above-described third resource may also be set at a timing when the base station device 151 does not transmit a millimeter wave signal, i.e., in a time slot allocated to the uplink. The terminal device 101 transmits a millimeter wave signal in the third resource in which the base station device 151 does not transmit a millimeter wave signal, and performs a detection process for the THz band signal in the fourth resource.According to the above-described settings, since the base station device 151 does not transmit a millimeter wave signal, the relay device does not relay the millimeter wave signal, and the terminal device 101 can measure the millimeter wave signal relayed by the relay device under interference-free conditions. Note that although it is assumed that a THz band signal is transmitted between another terminal device and a corresponding relay device, due to the high frequency of the signal, interference of the THz band signal with the signal transmitted between the terminal device 101 and the relay device can be ignored.

[0053] In this way, the terminal device 101 can recognize a relay device that does not have the communication function unit 131 and use the relay device as a virtual antenna. In the above example, the terminal device 101 transmits a signal for searching for a relay device during a period when the base station device 151 does not transmit a millimeter wave signal. However, the present invention is not limited to this. For example, the terminal device 101 may notify the base station device 151 that it will search for a relay device and receive search resources from the base station device 151. In this case, the terminal device 101 may transmit a search signal while the base station device 151 is transmitting a millimeter wave band signal. However, the base station device 151 is configured not to transmit a signal in the millimeter wave band radio resource used by the relay device to relay the signal, corresponding to the radio resource in which the terminal device 101 transmits the millimeter wave band search signal and the THz band radio resource in which the terminal device 101 transmits the search signal. This prevents interference due to a signal from the base station device 151 in the radio resource used by the terminal device 101 to search for a relay device. Furthermore, for example, it is assumed that the relay device can relay wireless signals in multiple frequency bands, as described above. Therefore, the terminal device 101 may perform signal detection processing in the multiple frequency bands. That is, the terminal device 101 may perform relay device detection processing using a combination of multiple frequency bands. Note that since the terminal device 101 knows the signal transmitted by itself, it may detect the signal from the relay device by performing correlation detection using a waveform obtained by frequency-converting the signal, or may simply detect the signal from the relay device by performing power detection in the resource after frequency conversion.

[0054] Furthermore, when multiple relay devices are present, the terminal device 101 may perform a detection process to detect each of the multiple relay devices. For example, the terminal device 101 may form multiple beams and perform a detection process for each beam to detect relay devices present in the direction of the beam, and may use other beams to detect relay devices present in other directions. That is, by performing a detection process for each beam, the terminal device 101 may detect relay devices present in different directions by separating them by beam. Note that by changing the beam used over time, it is possible to identify which beam a relay device is found for, but this is not limited to this. For example, the terminal device 101 may perform a relay device detection process using multiple beams in parallel, with each beam using a different sequence. That is, the terminal device 101 may identify the direction of a beam in which a relay device is present based on which sequence of a signal is detected. Also, for example, if all relay devices to be searched for perform the same frequency conversion, the terminal device 101 may perform a relay device detection process using multiple beams in parallel, with each beam using a different frequency resource. That is, the terminal device 101 can identify the direction of the beam in which the relay device is located, depending on the frequency resource in which the signal is detected.

[0055] 7 illustrates an example of a process flow in which the terminal device 101 searches for an intermediate device that does not have the communication function unit 131. The terminal device 101 transmits a search signal using a first resource (or a third resource) periodically or in response to the occurrence of a predetermined event (S701). For example, after the intermediate device is turned on by a user operation, the intermediate device converts the frequency of the search signal to a second resource (or a fourth resource if the intermediate device receives a search signal transmitted using the third resource) (S702), amplifies the signal, and then outputs the signal (S703). The terminal device 101 detects the intermediate device in response to receiving a wireless signal transmitted from the intermediate device using the second resource (S704). For example, the terminal device 101 determines whether the received signal is a signal that has been frequency-converted from a wireless signal transmitted by the terminal device 101, thereby determining whether the received signal is a signal that has been relayed by the intermediate device, and can determine whether a intermediate device exists based on the determination result. However, the present invention is not limited to this, and may determine that a relay device exists when power equal to or greater than a predetermined level is detected in the second resource. Then, upon determining that a relay device exists, the terminal device 101 communicates with the base station device 151 using the relay device as a virtual antenna.

[0056] In this way, when there is a relay device that does not have a communication function unit 131, the terminal device 101 can detect the relay device and use the relay device as a virtual antenna to communicate with the base station device 151.

[0057] (Device configuration) Next, a description will be given of an example configuration of the terminal device 101 and the relay devices 121 and 122 configured to execute the above-mentioned processing. Since the functions that the terminal device 101 and the relay devices 121 and 122 should have are as described above, only a rough configuration of the terminal device 101 and the relay devices 121 and 122 will be described below. Since the base station device 151 has roughly the same functions as conventional base station devices, it will not be described here. The detailed operation of the base station device 151 is as described above.

[0058] FIG. 8 shows an example of the hardware configuration of the communication function unit 131 and the control unit 501 of the terminal device 101 and the relay devices 121 and 122 according to this embodiment. Hereinafter, the communication function unit 131 and the control unit 501 of the relay devices may be simply referred to as relay devices. In one example, the terminal device 101 and the relay devices 121 and 122 include a processor 801, a ROM 802, a RAM 803, a storage device 804, and a communication circuit 805. The processor 801 is a computer including one or more processing circuits, such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit). The processor 801 reads and executes programs stored in the ROM 802 or the storage device 804 to perform the overall processing of the device and each of the above-mentioned processes. The ROM 802 is a read-only memory that stores information such as programs and various parameters related to the processing executed by the terminal device 101 and the relay devices 121 and 122. The RAM 803 functions as a workspace when the processor 801 executes a program and is a random access memory that stores temporary information. The storage device 804 is, for example, a removable external storage device. The communication circuit 805 is, for example, a circuit for wireless communication of 5G or its successor standards. While FIG. 8 illustrates one communication circuit 805, the terminal device 101 and the relay devices 121 and 122 may have multiple communication circuits. For example, the terminal device 101 and the relay devices 121 and 122 may have wireless communication circuits for 5G and its successor standards, respectively, and a common antenna for these circuits, thereby enabling the sidelink communication function. The terminal device 101 and the relay devices 121 and 122 may have separate antennas suitable for each standard. The terminal device 101 may also have a communication circuit conforming to a wireless communication standard other than a cellular communication standard, such as wireless LAN or Bluetooth (registered trademark). Furthermore, the relay devices 121 and 122 may have a communication circuit for wireless LAN or Bluetooth in addition to or instead of a communication circuit for cellular communication.

[0059] Fig. 9 is a diagram illustrating an example of the functional configuration of the terminal device 101. The terminal device 101 has a first communication unit 901, a second communication unit 902, a virtual antenna control unit 903, and an AI / ML function unit. Note that these functions can be implemented, for example, by the processor 801 executing a program stored in the ROM 802 or the storage device 804, or by the communication circuit 805. However, this is just one example, and the functions of Fig. 9 may be realized by other configurations. Also, the functions illustrated in Fig. 9 are just one example, and the various processes described above may be realized by function units other than these.

[0060] The first communication unit 901 is a functional unit for communicating with, for example, the communication function units 131 of the relay devices 121 and 122. The first communication unit 901 has, for example, a sidelink communication function. Alternatively, the first communication unit 901 may have a Bluetooth communication function or a wireless LAN communication function instead of or in addition to the sidelink communication function. Control communication with the relay devices 121 and 122 is performed using the first communication unit 901. The second communication unit 902 communicates with the base station device 151. User data communication and control data communication with the base station device 151 are performed via the second communication unit 902. When a virtual antenna is not used, the second communication unit 902 may directly transmit, for example, a millimeter wave band signal to the base station device 151. When a virtual antenna is used, the second communication unit 902 may transmit, for example, a THz band signal. The THz band signal is converted into a millimeter wave band signal via the relay devices 121 and 122 and transferred to the base station device 151. The second communication unit 902 also directly receives the millimeter wave band signal transmitted from the base station device 151, or receives the THz band signal converted by the relay devices 121 and 122.

[0061] The virtual antenna control unit 903 executes various controls to be performed when the relay devices 121 and 122 are used as virtual antennas and when they are used as virtual antennas. The virtual antenna control unit 903 detects relay devices using, for example, the first communication unit 901 or the second communication unit 902, and executes connection processing with the relay devices to use them as virtual antennas. The virtual antenna control unit 903 also executes, for example, the various control communications described above associated with using the virtual antennas via the first communication unit 901 or the second communication unit 902. The AI / ML function unit 904 executes various processes using AI and ML. For example, the AI / ML function unit 904 may execute the above-described CSI compression and beam selection. The AI / ML function unit 904 also generates and updates a trained model using machine learning as needed. For example, the AI / ML function unit 904 updates the trained model when the trained model becomes inappropriate due to environmental changes or the like. Furthermore, the AI / ML functional unit 904 executes the various control communications described above associated with the use of AI / ML, for example, via the second communication unit 902. For example, when it becomes necessary to update the trained model related to the compression and decompression of CSI, the AI / ML functional unit 904 can notify the base station device 151 of a change in the capability information of the terminal device 101.

[0062] 10 shows an example of a functional configuration of the communication function unit 131 and the control unit 501 (i.e., the parts other than the relay function unit 132) of the relay devices 121 and 122. The parts other than the relay function unit 132 of the relay devices 121 and 122 include, as their functions, a communication unit 1001, a capability information notifying unit 1002, and a measurement result notifying unit 1003. These functions can be implemented, for example, by the processor 801 executing a program stored in the ROM 802 or the storage device 804, or by the communication circuit 805. However, this is just an example, and the functions of FIG. 10 may be realized by other configurations. Furthermore, the functions shown in FIG. 10 are just an example, and the various processes described above may be realized by other functional units.

[0063] The communication unit 1001 has a function corresponding to the first communication unit 901 of the terminal device 101. That is, when the first communication unit 901 performs communication using the sidelink communication function, the communication unit 1001 also has the sidelink communication function. The capability information notifying unit 1002 notifies, for example, information on the capabilities of the relay function unit 132 to the terminal device 101 via the communication unit 1001. For example, the capability information notifying unit 1001 notifies, to the terminal device 101, information on whether the relay function unit 132 is included, the frequency band that the relay function unit 132 can use, and the number and configuration of antennas that can be used in the relay function unit 132. The measurement result notifying unit 1003, for example, measures the wireless quality of a signal received by the relay function unit 132 and notifies the terminal device 101 of the measurement result. The measurement result notifying unit 1003 is configured to, for example, monitor the received power of the signal at each antenna of the relay function unit 132 to acquire the wireless quality.

[0064] As described above, by performing appropriate control, the terminal device 101 according to this embodiment can use the relay device having an RF relay function as an extended antenna to communicate with the base station device 151. This makes it possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, which is to "Develop resilient infrastructure, promote sustainable industrialization, and foster innovation."

[0065] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

Claims

1. A terminal device connected to a base station device, A determination means for determining whether or not it is necessary to change the capability information notified to the base station device; a transmitting means for transmitting, in response to a determination that a change in the capability information is necessary, a signal for transmitting the capability information to the base station device while maintaining a connection with the base station device and in a state in which an inquiry for the capability information has not been received from the base station device; a notification means for notifying the base station device of the changed capability information; A terminal device comprising:

2. 2. The terminal device according to claim 1, wherein the notification means transmits the changed capability information to the base station device by including the changed capability information in the signal.

3. the signal is a signal requesting the base station device to transmit a message inquiring about the capability information, 2. The terminal device according to claim 1, wherein the notification means notifies the base station device of the capability information in response to receiving the message from the base station device.

4. 4. The terminal device according to claim 3, wherein the signal includes information indicating which item of the capability information is to be changed.

5. the terminal device converts a signal having a first frequency transmitted by the terminal device to a second frequency, amplifies the signal, and relays the signal to the base station device; and uses a relay device, which converts a signal having the second frequency transmitted by the base station device to the first frequency, amplifies the signal, and relays the signal to the terminal device, as a virtual antenna; the determining means determines that it is necessary to change the capability information in response to a loss of connection with the relay device used as the virtual antenna, or in response to a new establishment of a connection with the relay device used as the virtual antenna.

2. The terminal device according to claim 1 .

6. The terminal device holds a first trained model that compresses channel state information (CSI) between the terminal device and the base station device at a compression rate determined by a predetermined criterion through machine learning using the CSI as an input, and a second trained model that restores the CSI compressed by the first trained model; The capability information includes information indicating whether compression and decompression of the CSI can be performed using the first trained model and the second trained model, The determination means determines that the capability information needs to be changed when the CSI compressed by the first trained model cannot be restored by the second trained model.

2. The terminal device according to claim 1 .

7. The terminal device holds a trained model that selects which of the plurality of beams to use in communication with the base station device by machine learning using as input a measurement result of a signal transmitted from the base station device in a portion of the plurality of beams formed by the base station device, The capability information includes information indicating whether or not it is possible to select which of the plurality of beams to use in communication with the base station device using the measurement results of the part of the plurality of beams by using the learned model, and The determination means determines that a change in the capability information is necessary when a beam selected by inputting a measurement result of a signal transmitted from the base station device in the part of the plurality of beams into the trained model no longer matches a beam selected based on a measurement result of a signal transmitted from the base station device in all of the plurality of beams.

2. The terminal device according to claim 1 .

8. A control method executed by a terminal device connected to a base station device, comprising: determining whether it is necessary to change the capability information notified to the base station device; In response to the determination that the capability information needs to be changed, transmitting a signal to the base station device for transmitting the capability information to the base station device while maintaining a connection with the base station device and in a state in which no inquiry about the capability information has been received from the base station device; notifying the base station device of the changed capability information; A control method comprising:

9. A program for causing a computer installed in a terminal device to execute the control method according to claim 8.

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