Communication device, communication method, program, and communication system

Abstract

To provide a mechanism that enables bidirectional precoding operations between terminals.SOLUTION: A communication device that communicates with a counterpart terminal has a communication unit configured to transmit and receive precoded radio signals with the counterpart terminal, and to transmit a transmission instruction to the counterpart terminal for sending a transmission instruction for instructing the transmission of propagation path information report to the counterpart terminal, and a setting unit configured to set precoding for radio signals to be transmitted to the counterpart terminal, on the basis of the propagation path information report received from the counterpart terminal.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] In recent years, the 3rd Generation Partnership Project (3GPP) (registered trademark) has been working on developing specifications for LTE (Long Term Evolution) and 5G NR (5th Generation New Radio). Furthermore, in wireless communication, there is a precoding technique in which a signal is generated on the transmitting side taking into account current propagation path information in order to improve transmission efficiency. When precoding is performed between a base station and a terminal that conforms to the standards established by 3GPP, the base station determines the instructions to the terminal based on the communication conditions between the base station and the terminal, and then transmits a reference signal and a report instruction.The terminal also reports propagation path information to the base station in a configuration based on the instructions.The base station transmits precoded data based on the propagation path information reported from the terminal. On the other hand, 3GPP has formulated a standard specification called Sidelink communication (hereinafter referred to as Sidelink) that does not involve a base station, and this specification realizes direct wireless communication between terminals (UE: User Equipment) using an interface called PC5, without passing data through a base station or core network. Patent Document 1 proposes a method for Sidelink in which, based on a reference signal, propagation path information is returned to the terminal that transmitted the reference signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-526741 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of sidelink communication, since both terminals are moving, it is expected that the propagation path conditions will fluctuate more than in communication between a fixed base station and terminal. Therefore, it is desirable to perform bidirectional precoding between terminals to ensure stable communication.

[0005] The present invention has been made in consideration of at least one of the above-described problems, and an object of one aspect of the present invention is to provide a mechanism that enables bidirectional precoding operations between terminals. [Means for solving the problem]

[0006] A communication device according to one aspect of the present invention is a communication device that communicates with a communication partner terminal, and is characterized by having: a communication unit that transmits and receives precoded radio signals to the communication partner terminal, and transmits a transmission instruction to the communication partner terminal to instruct it to transmit a propagation path information report; and a setting unit that sets precoding for the radio signals to be transmitted to the communication partner terminal based on the propagation path information report received from the communication partner terminal. [Effects of the Invention]

[0007] According to the present invention, by performing a bidirectional precoding operation between terminals, stable communication can be achieved even when the communication conditions between the terminals change. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a communication system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing an example of the functional configuration of a terminal according to the embodiment. [Figure 3] FIG. 2 is a sequence diagram of the first embodiment. [Figure 4] 1 is a flowchart of the first embodiment. [Figure 5] 1 is a flowchart of the first embodiment. [Figure 6] FIG. 10 is a sequence diagram of the second embodiment. [Figure 7] 10 is a flowchart of a second embodiment. [Figure 8] 10 is a message format illustrating an example of a precoding change notification according to the second embodiment. [Figure 9] 10 is a message format illustrating an example of a precoding change notification according to the second embodiment. [Figure 10] FIG. 10 is a sequence diagram of the third embodiment. [Figure 11] 10 is a flowchart of a third embodiment. [Figure 12] FIG. 10 is a sequence diagram of the fourth embodiment. [Figure 13] 10 is a flowchart of a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0010] [First embodiment]

[0011] (System Configuration) Fig. 1 is a diagram showing an example of the system configuration of a communication device according to this embodiment. The system shown in Fig. 1 includes terminal A101 and terminal B102. In Fig. 1, it is assumed that connection processing for sidelink communication between the terminals has been completed, and sidelink communication is possible between terminal A101 and terminal B102.

[0012] (Functional configuration of communication device) Next, the functional configuration of the communication device according to this embodiment will be described. Note that the functional block configuration described below is merely an example.

[0013] Some or all of the functional blocks may be replaced with other functional blocks that perform similar functions, some functional blocks may be omitted, or additional functional blocks may be added. Furthermore, a single functional block described below may be divided into multiple functional blocks, or multiple functional blocks may be integrated into a single functional block. Furthermore, only some of the functional blocks may be configured in hardware, with the remaining functions configured in software. When a functional block is configured in software, a processor constituting the control unit 201 (described later) executes a control program for realizing the function stored in the storage unit 202 (described later). This provides the function of the functional block.

[0014] 2 is a functional block diagram showing an example of the functional configuration of terminal A 101 and terminal B 102 in this embodiment. In Fig. 2, a control unit 201 controls the operation of the terminal. A storage unit 202 stores information used by the control unit 201 for control and information related to communication.

[0015] The reception quality measurement unit 203 measures reception quality for generating a CSI (Channel State Information) report to be transmitted to a terminal of a communicating party, using a reference signal included in a radio signal transmitted from the terminal of a communicating party. Furthermore, the reception quality measurement unit 203 generates a CSI report to be transmitted to the terminal of a communicating party, based on the measured reception quality. Note that the CSI report may also be called a propagation path information report.

[0016] The precoding setting unit 204 determines the precoding operation and sets the operation based on the information in the CSI report. Also, the precoding setting unit 204 sets precoding for the radio signal to be transmitted to the terminal of the other party based on the CSI report received from the terminal of the other party.

[0017] Message generation section 205 generates messages such as a transmission instruction (CSI report transmission instruction) to instruct a terminal of a communicating party to transmit a CSI report, a precoding setting change notification, etc. Message analysis section 206 analyzes messages such as a CSI report transmission instruction and a precoding setting change notification received from a terminal of a communicating party. Note that the CSI report transmission instruction may also be called a propagation path information report transmission instruction.

[0018] Wireless communication unit 207 transmits and receives wireless signals to and from the counterpart terminal via sidelink communication. Wireless communication unit 207 also transmits a CSI report transmission instruction generated by message generation unit 205 to the counterpart terminal. Wireless communication unit 207 also transmits and receives precoded wireless signals to and from the counterpart terminal. When wireless communication unit 207 receives a CSI report transmission instruction from the counterpart terminal, it transmits the CSI report generated by reception quality measurement unit 203 to the counterpart terminal.

[0019] In addition, when configuring precoding based on a CSI report received from a communication partner terminal, if the currently configured precoding setting value is to be changed, the wireless communication unit 207 transmits a precoding setting change notification to the communication partner terminal.

[0020] Furthermore, when configuring precoding based on a CSI report received from a communicating terminal, if the currently configured precoding setting value is not to be changed, the wireless communication unit 207 does not send a precoding setting change notification to the communicating terminal.

[0021] The communication status determination unit 208 determines the status of communication via sidelink with the terminal of the other party of communication.

[0022] The reception quality measurement unit 203 is an example of a measurement unit. The precoding setting unit 204 is an example of a setting unit. The wireless communication unit 207 is an example of a communication unit. The message generation unit 205 is an example of a generation unit. The communication situation determination unit 208 is an example of a determination unit.

[0023] (Processing example) The operation of the first embodiment will be described with reference to the operation sequence diagram shown in FIG. 3 and the flowcharts shown in FIGS.

[0024] Fig. 3 is an example of a sequence showing a processing procedure for performing sidelink communication while performing bidirectional precoding between terminal A101 and terminal B102 in the first embodiment. Fig. 4 and Fig. 5 are flowcharts showing the operations of terminal A101 and terminal B102 based on the contents of the sequence diagram in Fig. 3.

[0025] Terminal A101 and terminal B102 realize the processes shown in the flowcharts of Figures 4 and 5 by causing the control unit 201 shown in Figure 2 to execute a control program stored in the storage unit 202. Note that some of the processes are realized in cooperation with the hardware and functional units described above.

[0026] In FIG. 3, terminal A101 and terminal B102 are connected by sidelink communication via their respective wireless communication units 207 (F301). Terminal A101 determines the communication status with terminal B102 (F302, S401). For example, terminal A101 may measure the reception quality of a radio signal received from terminal B102 in the processing procedure of F301, and determine the communication status with terminal B102 based on the measured reception quality. Furthermore, terminal A101 may determine that the precoding information needs to be revised if the reception quality is equal to or lower than a predetermined threshold. Alternatively, terminal A101 may determine that the precoding information needs to be revised if it has moved a predetermined distance or more from the location where the precoding information was previously set. If terminal A101 determines in F302 and S401 that the precoding used for transmission by its own terminal needs to be revised, it transmits a CSI report transmission instruction message to terminal B102 (F303, S402). The CSI report transmission instruction message may include a pmi-FormatIndicator. The pmi-FormatIndicator indicates whether the terminal B 102 includes a PMI corresponding to the wideband in the CSI report or a PMI for each subband in the CSI report.

[0027] Furthermore, terminal A101 transmits a reference signal to terminal B102 (F304). The reference signal may be, for example, a Channel State Information Reference Signal (CSI-RS).

[0028] When terminal B102 receives the CSI report transmission instruction message in the processing procedure of S405, it measures the reception quality of the reference signal (F304) transmitted from terminal A101 (S406). Terminal B102 generates a CSI report from information on the measured reception quality and transmits it to terminal A101 (F305, S407). Note that transmitting the CSI report may also be referred to as CSI feedback. When terminal A101 receives the CSI report in F305 and S403, it calculates and sets precoding information using the received CSI report (F306, S404). The CSI report may include, for example, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), etc. Terminal A101 may also calculate the precoding information based on the PMI.

[0029] Thereafter, terminal A101 transmits a radio signal to terminal B102 using the set precoding information (F307). Note that transmitting a radio signal using precoding information means, for example, transmitting a radio signal multiplied by precoding information (precoding matrix).

[0030] Similarly, terminal B102 determines the communication status with terminal A101 (F308, S501). The determination of the communication status may be the same as the determination method performed by terminal A101 described in the processing procedures of F302 and S401. If terminal B102 determines in F308 and S501 that it is necessary to review the precoding used for transmission by its own terminal, it transmits a CSI report transmission instruction message to terminal A101 (F309, S502). Furthermore, terminal B102 transmits a reference signal to terminal A101 (F310). The reference signal may be, for example, a CSI-RS.

[0031] When terminal A101 receives the CSI report transmission instruction message in the processing procedure of S505, it measures the reception quality of the reference signal (F310) transmitted from terminal B102 (S506). Terminal A101 generates a CSI report from information on the measured reception quality and transmits it to terminal B102 (F311, S507). When terminal B102 receives the CSI report in F312 and S503, it calculates and sets precoding information using the received CSI report (F312, S504). The CSI report may include, for example, CQI, PMI, RI, etc. Furthermore, terminal B102 may calculate the precoding information based on the PMI.

[0032] Thereafter, terminal B102 transmits a signal to terminal A101 using the set precoding information (F313).

[0033] According to the first embodiment described above, terminal A101 and terminal B102 perform precoding in both directions, which enables stable communication even when the communication conditions between the terminals change.

[0034] [Second embodiment] The system configuration and the functional configuration of the device according to the second embodiment are the same as those of the first embodiment. The operation of the second embodiment will be described with reference to the operation sequence diagram shown in Fig. 6 and the flowchart shown in Fig. 7.

[0035] Fig. 6 is an example of a sequence showing a processing procedure for performing sidelink communication while performing bidirectional precoding between terminal A101 and terminal B102. Fig. 7 is a flowchart showing the operations of terminal A101 and terminal B102 based on the sequence contents of Fig. 6.

[0036] Terminal A101 and terminal B102 realize the processes shown in the flowchart by the control unit 201 in Fig. 2 executing a control program stored in the storage unit 202. Note that some of the processes are realized in cooperation with the hardware and functional units described above.

[0037] In FIG. 6, terminal A101 and terminal B102 are connected by sidelink communication via their respective wireless communication units 207 (F601). Terminal A101 determines the communication status with terminal B102 (F602, S701). The communication status determination may be the same as the determination method described in the first embodiment. If terminal A101 determines in F602 and S701 that it is necessary to review the precoding used for transmission by its own terminal, it transmits a CSI report transmission instruction message to terminal B102 (F603, S702). Terminal A101 also transmits a reference signal to terminal B102 (F604). The reference signal may be, for example, a CSI-RS.

[0038] Upon receiving the CSI report transmission instruction message, terminal B102 measures the reception quality of the reference signal transmitted from terminal A101 (F604). Terminal B102 transmits a CSI report to terminal A101 based on information about the measured reception quality (F605). Upon receiving the CSI report in F605 and S703, terminal A101 calculates and sets precoding information using the received CSI report (F606, S704). The CSI report may include, for example, CQI, PMI, RI, etc. Furthermore, terminal A101 may calculate the precoding information based on the PMI. When terminal A101 changes the set precoding information in the processing procedures of F606 and S704 (S705), terminal A101 transmits a precoding change notification message to terminal B102 (F607, S706).

[0039] When terminal B102 receives the precoding change notification message from terminal A101 in F607 (S707), it transmits a CSI report transmission instruction message to terminal A101 (F608, S708). Terminal B102 also transmits a reference signal to terminal A101 (F609). The reference signal may be, for example, a CSI-RS.

[0040] Upon receiving the CSI report transmission instruction message in S608, terminal A101 measures the reception quality of the reference signal received from terminal B102. Terminal A101 generates a CSI report from information on the measured reception quality and transmits it to terminal B102 (F610). Upon receiving the CSI report in F610 and S709, terminal B102 calculates and sets precoding information using the received CSI report (F611, S710). The CSI report may include, for example, CQI, PMI, RI, etc. Furthermore, terminal B102 may calculate the precoding information based on the PMI.

[0041] Thereafter, terminal A101 transmits a signal to terminal B102 using the set precoding information (F612). Furthermore, terminal B102 transmits a signal to terminal A101 using the set precoding information (F613).

[0042] In the second embodiment described above, when terminal A101 changes the precoding information (that is, when the precoding information is changed due to a change in communication conditions), terminal A101 transmits a precoding change notification message F607 to terminal B102. Furthermore, terminal B102, which has received the precoding change notification message, requests terminal A101 to transmit a CSI report to review its own precoding settings (F608).

[0043] As a result, when a change occurs in the precoding setting of terminal A101, it becomes possible to quickly review the precoding setting of terminal B102. Furthermore, as a result, terminal A101 and terminal B102 can quickly perform synchronized precoding operations in both directions, it becomes possible to achieve communication that is even more stable than in the first embodiment.

[0044] 8 shows an example of a message format when a precoding change notification message is notified by SCI (Sidelink Control Information). By setting a Precoding report in the SCI, it is possible to notify a precoding setting change. Note that, although the second embodiment shows an example in which a 2-bit field is set, it may be 1 bit or 3 bits.

[0045] 9 shows an example of a message format when a precoding change notification message is notified by RRC (Radio Resource Control). By setting reportPrecoding-r16 in the ReportConfigNR-SL message of the RRC message, it becomes possible to notify a change in the precoding setting.

[0046] [Third embodiment] The system configuration and the functional configuration of the device according to the third embodiment are the same as those of the first embodiment.

[0047] The operation of the third embodiment will be described with reference to the operation sequence diagram shown in FIG. 10 and the flowchart shown in FIG.

[0048] Fig. 10 is an example of a sequence showing a processing procedure for performing sidelink communication while performing bidirectional precoding between terminal A101 and terminal B102. Fig. 11 is a flowchart showing the operations of terminal A101 and terminal B102 based on the sequence of Fig. 10.

[0049] Terminal A101 and terminal B102 realize the processes shown in the flowchart by the control unit 201 in Fig. 2 executing a control program stored in the storage unit 202. Note that some of the processes are realized in cooperation with the hardware and functional units described above.

[0050] In FIG. 10, terminal A101 and terminal B102 are connected by sidelink communication via their respective wireless communication units 207 (F1001).

[0051] Terminal A101 determines the communication status with terminal B102 (F1002, S1101). The communication status determination may be the same as the determination method described in the first embodiment. If terminal A101 determines in F1002 and S1101 that it is necessary to review the precoding used for transmission by its own terminal, it transmits a CSI report transmission instruction message to terminal B102 (F1003, S1102). Terminal A101 also transmits a reference signal to terminal B102 (F1004). The reference signal may be, for example, a CSI-RS.

[0052] Upon receiving the CSI report transmission instruction message, terminal B102 measures the reception quality of the reference signal received from terminal A101 (F1004). Terminal B102 generates a CSI report from information about the measured reception quality and transmits it to terminal A101 (F1005). After transmitting the CSI report, terminal B102 transmits a reference signal to terminal A101 (F1007). The reference signal may be, for example, a CSI-RS.

[0053] In F1005 and S1103, when terminal A101 receives the CSI report, terminal A101 calculates and sets precoding information using the received CSI report (F1006, S1104). The CSI report may include, for example, a CQI, a PMI, an RI, etc. Terminal A101 may also calculate the precoding information based on the PMI.

[0054] When terminal A101 changes the configured precoding information in the processing procedures of F1006 and S1104 (S1105), terminal A101 measures the reception quality of a reference signal (F1007) received from terminal B102. Terminal A101 also creates a CSI report based on the measured reception quality and transmits the created CSI report to terminal B102 together with a precoding change notification message (F1008, S1106). When terminal B102 receives the precoding change notification message and CSI report from terminal A101 in F1108 and S1107, it calculates and sets precoding information using the received CSI report (F1009, S1108). The CSI report may include, for example, CQI, PMI, RI, etc. Terminal B102 may also calculate the precoding information based on the PMI. Thereafter, terminal A101 transmits a signal to terminal B102 using the set precoding information (F1010). Furthermore, terminal B102 transmits a signal to terminal A101 using the set precoding information (F1011).

[0055] In the third embodiment described above, terminal B102 transmits a CSI report to terminal A101 (F1005), and then subsequently transmits a reference signal (F1007). Furthermore, when terminal A101 changes the precoding information setting based on the received CSI report, terminal A101 measures the reference signal (F1007) transmitted from terminal A101, and transmits both a precoding change notification and a CSI report to terminal B102 (F1008).

[0056] As a result, when a change occurs in the precoding setting of terminal A, it becomes possible to review the precoding setting of terminal B102 more quickly than in the second embodiment. Furthermore, this also enables terminal A101 and terminal B102 to perform synchronized precoding operations more quickly in both directions, making it possible to achieve more stable communication than in the second embodiment.

[0057] [Fourth embodiment] The system configuration and the functional configuration of the device according to the fourth embodiment are the same as those of the first embodiment.

[0058] The operation of the fourth embodiment will be described with reference to the operation sequence diagram shown in FIG. 12 and the flowchart shown in FIG.

[0059] Fig. 12 is an example of a sequence showing a processing procedure for performing sidelink communication while performing bidirectional precoding between terminal A101 and terminal B102. Fig. 13 is a flowchart showing the operations of terminal A101 and terminal B102, based on the sequence contents of Fig. 11.

[0060] Terminal A101 and terminal B102 realize the processes shown in the flowchart by the control unit 201 in Fig. 2 executing a control program stored in the storage unit 202. Note that some of the processes are realized in cooperation with the hardware and functional units described above.

[0061] In FIG. 12, terminal A101 and terminal B102 are connected by sidelink communication via their respective wireless communication units 207 (F1201). Terminal A101 determines the communication status with terminal B102 (F1202, S1301). The communication status determination may be the same as the determination method described in the first embodiment. If terminal A101 determines in F1202 and S1301 that it is necessary to review the precoding used for transmission by its own terminal, it transmits a CSI report transmission instruction message to terminal B102 (F1203, S1302). Terminal A101 also transmits a reference signal to terminal B102 (F1204). The reference signal may be, for example, a CSI-RS.

[0062] Upon receiving the CSI report transmission instruction message (F1203, S1307), terminal B102 measures the reception quality of the reference signal (F1204) received from terminal A101 (S1308). Subsequently, terminal B102 generates a CSI report from information on the measured reception quality and transmits it to terminal A101 (F1205, S1309). After transmitting the CSI report, terminal B102 transmits a reference signal to terminal A101 (F1206) before completing the review of the precoding configuration (i.e., before completing the processing procedure of F1209 in FIG. 12). The reference signal may be, for example, a CSI-RS.

[0063] Meanwhile, terminal A101 measures the reception quality of the reference signal (F1206) transmitted from terminal B102 (S1305), generates a CSI report from the information on the measured reception quality, and transmits it to terminal B102 (F1207, S1306).

[0064] Terminal A101 calculates and sets precoding information using the CSI report received in F1205 and S1303 (F1208, S1304). The CSI report may include, for example, CQI, PMI, RI, etc. Terminal A101 may also calculate the precoding information based on the PMI. 12, the processing procedure F1208 is illustrated as being executed after the processing procedure F1207, but this is not limiting. Terminal A101 can also execute the processing procedure F1208 after receiving a CSI report from terminal B102 (i.e., after the processing procedure F1205), as in FIG.

[0065] Similarly, terminal B102 calculates and sets precoding information using the CSI report received in F1207 and S1310 (F1209, S1311). The CSI report may include, for example, CQI, PMI, RI, etc. Terminal B102 may also calculate the precoding information based on the PMI. Thereafter, terminal A101 transmits a signal to terminal B102 using the set precoding information (F1210). Terminal B102 also transmits a signal to terminal A101 using the set precoding information (F1211).

[0066] In the fourth embodiment described above, terminal B102 transmits a CSI report to terminal A101 (F1205), and then subsequently transmits a reference signal (F1206). Furthermore, terminal A101 measures the reference signal transmitted from terminal B102 (F1206), and transmits a CSI report to terminal B102 (F1207).

[0067] In the fourth embodiment, terminal A101 does not transmit a precoding change notification to terminal B102, thereby reducing the processing load on terminal A101. This enables terminal A101 and terminal B102 to perform synchronized precoding operations more quickly in both directions, thereby enabling more stable communication than in the second embodiment.

[0068] [Other embodiments] The present invention provides a program that realizes one or more of the functions of the first to fourth embodiments to a system or device via a network or a storage medium. The present invention can also be realized by a process in which one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

[0069] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention.

[0070] The following additional notes are provided regarding the above-described embodiments.

[0071] (Appendix 1) A communication device for communicating with a communication partner terminal, a communication unit that transmits and receives a precoded radio signal to and from the terminal of the other party of communication, and transmits a transmission instruction to the terminal of the other party of communication, the transmission instruction instructing the terminal to transmit a channel state information report; a setting unit that sets precoding for a radio signal to be transmitted to the terminal of the other communication party based on a channel information report received from the terminal of the other communication party; A communication device having:

[0072] (Appendix 2) when receiving a transmission instruction from the other terminal of communication to instruct transmission of a channel state information report, the communication unit transmits the channel state information report to the other terminal of communication; 2. The communication device of claim 1.

[0073] (Appendix 3) When setting precoding based on the propagation path information report received from the terminal of the other communication party, if the communication unit changes a currently set precoding setting value, it transmits a precoding setting change notification to the terminal of the other communication party. 3. The communication device according to claim 1 or 2.

[0074] (Appendix 4) The communication device according to any one of appendices 1 to 3, wherein when configuring precoding based on a propagation path information report received from the terminal of the other communication partner, if the currently configured precoding setting value is not changed, the communication unit does not send a precoding setting change notification to the terminal of the other communication partner.

[0075] (Appendix 5) The communication unit transmits the precoding setting change notification using SCI (Sidelink Control Information). 5. The communication device according to claim 3 or 4.

[0076] (Appendix 6) The communication unit transmits the precoding setting change notification using an RRC (Radio Resource Control) message. 5. The communication device according to claim 3 or 4.

[0077] (Appendix 7) The communication unit transmits a propagation path information report to the communication partner terminal in addition to the precoding setting change notification. 5. The communication device according to claim 3 or 4.

[0078] (Appendix 8) A communication method executed by a communication device that communicates with a communication partner terminal, comprising: transmitting and receiving a precoded radio signal to and from the terminal of the other party of communication, and transmitting a transmission instruction to the terminal of the other party of communication, the transmission instruction instructing the terminal of the other party of communication to transmit a channel state information report; setting precoding for a radio signal to be transmitted to the terminal of the other communication party based on a channel information report received from the terminal of the other communication party; A communication method including:

[0079] (Appendix 9) A communication device that communicates with a communication partner terminal, transmitting and receiving a precoded radio signal to and from the terminal of the other party of communication, and transmitting a transmission instruction to the terminal of the other party of communication, the transmission instruction instructing the terminal of the other party of communication to transmit a channel state information report; setting precoding for a radio signal to be transmitted to the terminal of the other communication party based on a channel information report received from the terminal of the other communication party; A program to execute.

[0080] (Appendix 10) 10. A communication system including a plurality of communication devices according to claim 1. [Explanation of symbols]

[0081] 101 Terminal A 102 Terminal B

Claims

1. A communication device for communicating with a communication partner terminal, a communication unit that transmits and receives a precoded radio signal to and from the terminal of the other party of communication, and transmits a transmission instruction to the terminal of the other party of communication, the transmission instruction instructing the terminal to transmit a channel state information report; a setting unit that sets precoding for a radio signal to be transmitted to the terminal of the other communication party based on a channel information report received from the terminal of the other communication party; A communication device having:

2. when receiving a transmission instruction from the other terminal of communication to instruct transmission of a channel state information report, the communication unit transmits the channel state information report to the other terminal of communication; The communication device according to claim 1 .

3. When setting precoding based on the propagation path information report received from the terminal of the other communication party, if the communication unit changes a currently set precoding setting value, it transmits a precoding setting change notification to the terminal of the other communication party. The communication device according to claim 1 .

4. When setting precoding based on a propagation path information report received from the terminal of the other communication party, if the communication unit does not change a currently set precoding setting value, the communication unit does not transmit a precoding setting change notification to the terminal of the other communication party. The communication device according to claim 1 .

5. The communication unit transmits the precoding setting change notification using SCI (Sidelink Control Information). The communication device according to claim 3 .

6. The communication unit transmits the precoding setting change notification using an RRC (Radio Resource Control) message. The communication device according to claim 3 .

7. The communication unit transmits a propagation path information report to the communication partner terminal in addition to the precoding setting change notification. The communication device according to claim 3 .

8. A communication method executed by a communication device that communicates with a communication partner terminal, comprising: transmitting and receiving a precoded radio signal to and from the terminal of the other party of communication, and transmitting a transmission instruction to the terminal of the other party of communication, the transmission instruction instructing the terminal of the other party of communication to transmit a channel state information report; setting precoding for a radio signal to be transmitted to the terminal of the other communication party based on a channel information report received from the terminal of the other communication party; A communication method including:

9. A communication device that communicates with a communication partner terminal, transmitting and receiving a precoded radio signal to and from the terminal of the other party of communication, and transmitting a transmission instruction to the terminal of the other party of communication, the transmission instruction instructing the terminal of the other party of communication to transmit a channel state information report; setting precoding for a radio signal to be transmitted to the terminal of the other communication party based on a channel information report received from the terminal of the other communication party; A program to execute.

10. A communication system comprising a plurality of communication devices according to claim 1.

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