Communication terminal, communication device, and program

Abstract

To provide a mechanism for transmitting and receiving feedback information in groupcast communication performed by V2X terminals.SOLUTION: Disclosed is a communication terminal that performs sidelink communication with another communication terminal, the communication terminal including reception means for receiving a reference signal included in the sidelink communication, calculation means for calculating a predetermined index on the basis of the reference signal, and transmission means for transmitting feedback information including the predetermined index to the other communication terminal in a case where a cast type included in control information received in the sidelink communication is groupcast SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] V2X (Vehicle to Everything) is a vehicle communication technology that enables network connections and mutual cooperation between vehicles, vehicles and roadside equipment, and vehicles and pedestrians. V2X is expected to be used to support safe driving by warning drivers of hidden dangers that cannot be detected by conventional in-vehicle devices such as cameras and LiDAR.

[0003] In V2X, a transmitter can communicate directly with a receiver via a sidelink. Unlike the Uu link (air interface between a network device and a user device) of a cellular network, sidelink communication is performed via a newly defined PC5 interface (air interface between V2X devices) for V2X. The frequency band used for V2X communication is specified as Band 47 (5855 MHz to 5925 MHz) in the specifications of the 3GPP (3rd Generation Partnership Project) (registered trademark).

[0004] The 3GPP specifications also define three types of sidelink communication formats: broadcast, unicast, and groupcast, each of which targets different types of terminals. Broadcast targets all terminals within transmission distance, unicast targets one specific terminal, and groupcast targets multiple specific terminals.

[0005] Among these, GroupCast is expected to be used in automobile platooning. When automobiles are platooning, the formation and management of the platoon and the adjustment of vehicle spacing within the platoon are carried out while driving, and the information required for this is exchanged between devices within the platoon via GroupCast communications.

[0006] Because V2X is expected to be used for safety-related applications, high reliability is required in wireless communications, and there is a demand for methods to reduce the interference that a communicating terminal causes to other wireless communications taking place in the vicinity of the terminal itself.

[0007] In wireless communication, methods such as transmission power control and precoding are used to reduce interference caused by a communicating terminal to other wireless communications taking place around the terminal. These methods are realized by feedback control. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2022-526741 Summary of the Invention [Problem to be solved by the invention]

[0009] Conventionally, in Uu communication conforming to the 3GPP standard, for example, feedback information is transmitted and received using a CSI report (Channel State Information Report). Patent Document 1 describes a technique in which a first device transmits a CSI report to a second device based on a reference signal in sidelink communication.

[0010] However, the technology described in Patent Document 1 focuses on unicast and does not take into consideration sending and receiving feedback information via groupcast. Furthermore, in the past, sending and receiving feedback information via groupcast has not been performed between terminals that comply with the 3GPP standard.

[0011] Therefore, with groupcast, it is not possible to apply interference avoidance techniques such as feedback control, transmission power control, and precoding.As a result, when other wireless communication terminals are present around a V2X terminal traveling in a convoy, there is a concern that groupcast communication performed by the V2X terminal may interfere with other wireless communication terminals.

[0012] In view of the above-mentioned problems, an object of the present invention is to provide a mechanism for transmitting and receiving feedback information in groupcast communication performed by V2X terminals. [Means for solving the problem]

[0013] The communication device of the present invention that achieves the above-mentioned object is a communication terminal that performs sidelink communication with another communication terminal, and is characterized by comprising: a receiving means for receiving a reference signal included in the sidelink communication; a calculating means for calculating a predetermined indicator based on the reference signal; and a transmitting means for transmitting feedback information including the predetermined indicator to the other communication terminal when the cast type included in the control information received in the sidelink communication is groupcast. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a mechanism for transmitting and receiving feedback information in groupcast communication performed by V2X terminals. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of a communication system according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram illustrating an example of a configuration of a communication system according to an embodiment of the present invention. [Figure 3] FIG. 2 is a block diagram showing an example of the functional configuration of a terminal (UE) in the present embodiment. [Figure 4] FIG. 2 is a sequence diagram of the first embodiment. [Figure 5] This is an example of the data structure of SCI. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, 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 claimed. 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.

[0017] [First embodiment]

[0018] (System Configuration) Fig. 1 is a diagram showing an example of the system configuration of a communication device according to this embodiment. As shown in Fig. 1, the system is made up of terminal A101, terminal B102, terminal C103, and terminal D104. In Fig. 1, connection processing for sidelink communication between terminals (UEs, communication terminals) has been completed, and terminal A101 is in a state where sidelink communication is possible between terminal B102, terminal C103, and terminal D104.

[0019] As shown in FIG. 2, in this embodiment, terminal A101, terminal B102, terminal C103, and terminal D104 are mounted on vehicles traveling in a platoon. Terminal A101 transmits and receives information necessary for organizing and managing the platoon and for adjusting inter-vehicle distances between terminals B102, C103, and D104 using groupcast communication. It is assumed that information indicating which group each terminal belongs to (e.g., a group ID) is set in advance for each terminal. It is also assumed that information indicating that terminal B102, terminal C103, and terminal D104 are included in at least terminal A101's group (e.g., the IDs of terminal B102, terminal C103, and terminal D104) is set in advance for at least terminal A101.

[0020] (Functional configuration of the device) Next, the functional configuration of the communication device according to this embodiment will be described with reference to Fig. 3. Note that the functional block configuration described below is merely an example.

[0021] Some (or in some cases all) of the functional blocks described below 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, one functional block described below may be divided into multiple functional blocks, or multiple functional blocks may be integrated into one functional block. Furthermore, only some of the functional blocks may be configured in hardware, with the remaining functions configured in software. When the functional blocks are configured in software, a processor constituting the control unit 201 described below executes a control program for realizing the functions stored in the storage unit 202 described below. This provides the functions of each functional block.

[0022] FIG. 3 is a block diagram showing an example of the functional configuration of terminal A101, terminal B102, terminal C103, and terminal D104 in this embodiment. In FIG. 3, 201 is a control unit that controls the operation of the terminals. 202 is a storage unit that stores information used by the control unit 201 for control and information related to communication. 203 is a reception quality measurement unit that measures reception quality from a reference signal received from a remote terminal. 204 is a communication setting unit that performs communication setting reflecting feedback information such as a channel state information report received from the remote terminal. 205 is a feedback information generation unit that generates feedback information such as a channel state information report to be transmitted to the remote terminal. 206 is a feedback information processing unit that processes feedback information such as a channel state information report received from the remote terminal. 207 is a wireless communication unit that transmits and receives information to and from other terminals using sidelink communication. 208 is a control information processing unit that processes sidelink control information received by 207. The communication setting unit, control information processing unit, and wireless communication unit are examples of a receiving means and a transmitting means. The reception quality measurement unit is an example of a calculating means.

[0023] (Processing example) The operation of this embodiment will be described using the operation sequence diagram shown in Fig. 4. In Fig. 4, terminal A101 is connected to terminal B102, terminal C103, and terminal D104 by sidelink communication via wireless communication unit 207 (F301).

[0024] Terminal A101 transmits sidelink control information (hereinafter, SCI), and terminal B102, terminal C103, and terminal D104 receive the SCI transmitted from terminal A101 (F302).

[0025] Here, the SCI defines a first-stage SCI (1st-stage SCI) and a second-stage SCI (2nd-stage SCI). The first-stage SCI is transmitted on a PSCCH (Physical Sidelink Control Channel). The second-stage SCI is transmitted on a PSSCH (Physical Sidelink Shared Channel). The first-stage SCI includes information related to scheduling of the PSSCH, such as frequency resources and time resources of the PSSCH, the format of the second-stage SCI, and information related to resource reservation. The second-stage SCI includes information necessary for decoding the PSSCH, such as information indicating the destination of data included in the PSSCH and a Hybrid Automatic Repeat reQuest (HARQ) process number.

[0026] FIG. 5 is a diagram illustrating an example of an SCI on a PSSCH according to an embodiment of the present invention. Specifically, FIG. 5 illustrates 'SCI format 2-A' used in the first and second modes of V2X communication. Note that SCI format 2-A is a second-stage SCI. The first mode is a mode in which a base station allocates (schedules) radio resources to be used for sidelink communication to a terminal. The second mode is a mode in which a terminal itself selects radio resources to be used for sidelink communication from a pre-configured resource pool.

[0027] An example of 'SCI format 2-A' is shown below. In HARQ operation, SCI format 2-A is used for decoding PSSCH in the following cases: when HARQ-ACK information includes ACK or NACK, when HARQ-ACK information includes only NACK, or when there is no feedback of HARQ-ACK information.

[0028] The following information is transmitted in SCI format 2-A. HARQ process number - 4 bits New Data indicator - 1 bit Redundancy version-2bit Source ID-8bit Destination ID-16bit ·HARQ feedback enabled / disabled indicator-1bit Cast type indicator - 2bit ·CSI request-1bit.

[0029] The cast type is defined in the 'Cast type indicator' (F07) of the SCI described above. That is, terminal B102, terminal C103, and terminal D104 can identify the cast type of data transmitted by terminal A101 based on the 'Cast type indicator' included in the SCI received via PSSCH. Returning to Figure 4, the explanation will continue. The cast type is set to one of unicast, groupcast, and broadcast.

[0030] In F303, when terminal B102, terminal C103, and terminal D104 determine that the cast type of the data transmitted by terminal A101 is groupcast (F303), they perform the following: They receive the reference signal transmitted from terminal A101 and measure information related to reception quality (F304). The reference signal may be, for example, a Channel State Information-Reference Signal (CSI-RS) or a Demodulation Reference Signal (DM-RS). Terminal B102, terminal C103, and terminal D104 transmit feedback information including information related to the measured reception quality to terminal A101 (F305). Note that the information related to reception quality is an example of a predetermined index.

[0031] Here, the feedback information may include information for identifying a terminal group performing groupcast communication (for example, a group ID). The feedback information may further include information for identifying terminals in the group (for example, terminal IDs) and information related to the reception quality measured in the processing procedure of F305. The feedback information may also be a channel state information report (CSI report). Examples of the data structure of a channel state information report are shown in Tables 1 to 3.

[0032] [Table 1]

[0033] [Table 2]

[0034] [Table 3] As shown in Tables 1 to 3, the information on reception quality may include, for example, a CSI-RS resource indicator (CRI) and a channel quality indicator (CQI). Furthermore, the information on reception quality may further include a rank indicator (RI) and / or a precoding matrix indicator (PMI). Furthermore, the information on reception quality may include reference signal received power (RSRP), reference signal received quality (RSRQ), and / or received signal strength (RSSI), which are obtained by measuring a reference signal. RSRP stands for Reference Signal Received Power. RSRQ stands for Reference Signal Received Quality. RSSI stands for Received Signal Strength Indicator. RSRP, RSRQ, and RSSI may be PSSCH-RSRP, PSCCH-RSRP, and SL RSSI (SideLink RSSI), respectively. The information about the reception quality may also include a signal-to-interference-plus-noise ratio (SINR).

[0035] Terminal B102, terminal C103, and terminal D104 may transmit feedback information to terminal A101 using a Medium Access Control Element (MAC CE) transmitted on a PSSCH. Alternatively, terminal B102, terminal C103, and terminal D104 may transmit feedback information to terminal A101 using a Physical Sidelink Feedback Channel (PSFCH).

[0036] Furthermore, terminal B102, terminal C103, and terminal D104 may transmit all or part of the feedback information using a measurement report specified in an RRC message. For example, the measurement report may include information on reception quality. More specifically, the measurement report may include PSSCH-RSRP, PSCCH-RSRP, and / or SL RSSI (SideLink RSSI). Furthermore, in addition to the information on reception quality, the measurement report may include information for identifying a terminal group performing groupcast communication (for example, a group ID) and information for identifying terminals within the group (for example, terminal IDs).

[0037] By including information for identifying the terminal group in the feedback information, terminal A101 can identify the group that is the sender of the feedback information, even if there are multiple terminal groups performing groupcast communication. Furthermore, by including information for identifying a terminal within the group in the feedback information, terminal A101 can do the following: It can identify the terminal that was unable to receive the feedback information among all the terminals performing groupcast communication, that is, terminal B102, terminal C103, and terminal D104.

[0038] Upon receiving the feedback information in F305, terminal A101 sets precoding information (performs precoding configuration) based on the feedback information received from each terminal. Furthermore, terminal A101 may perform transmission power configuration based on RSRP or the like included in the feedback information received from each terminal (F306). Furthermore, terminal A101 may perform beamforming configuration based on the feedback information.

[0039] Thereafter, terminal A101 transmits signals to terminal B102, terminal C103, and terminal D104 in accordance with the precoding setting, transmission power setting, and / or precoding setting (F307). At this time, terminal A101 may transmit precoded signals to terminal B102, terminal C103, and terminal D104 in accordance with the precoding setting. Terminal A101 may also control the transmission power of signals to be transmitted to terminal B102, terminal C103, and terminal D104 in accordance with the transmission power setting. Terminal A101 may also perform beamforming in accordance with the beamforming setting when transmitting signals.

[0040] In this embodiment, the operation is described in the case where feedback information is transmitted and received mainly by terminal A101, but terminal B102, terminal C103, and terminal D104 may also perform the same operation as terminal A101. Also, in this embodiment, terminal B102, terminal C103, and terminal D104 transmit feedback information, but this is not limited to this. In other words, instead of all of terminal B102, terminal C103, and terminal D104 transmitting feedback information, some of the terminals performing groupcast communication may transmit feedback information.

[0041] In this embodiment, terminal A101 receives all of the feedback information transmitted by terminal B102, terminal C103, and terminal D104, but this is not limiting. In this embodiment, terminal A101 may receive feedback information only from some of the terminals that are performing groupcast communication, rather than receiving feedback information from all of the terminals. The above process enables terminal A101 to transmit and receive feedback information to and from terminal B102, terminal C103, and terminal D104 with which it is performing groupcast communication.

[0042] [Other embodiments] The present invention may be implemented by providing a recording medium on which program code for software that realizes the above-described functions is recorded to a system or device, and having a computer (CPU, MPU) in the system or device read and execute the program code stored on the recording medium. In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiments, and the recording medium on which the program code is stored constitutes the present invention.

[0043] Examples of storage media that can be used to supply the program code include flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, ROMs, and DVDs.

[0044] Furthermore, the above-mentioned functions may be realized not only by the computer executing the read program code, but also by the operating system (OS) running on the computer performing some or all of the actual processing based on the instructions of the program code. OS is an abbreviation for Operating System.

[0045] Furthermore, the program code read from the storage medium may be written to a memory provided on a function expansion board inserted into a computer or a function expansion unit connected to the computer, and a CPU provided on the function expansion board or function expansion unit may then perform some or all of the actual processing based on the instructions of the program code to realize the above-mentioned functions.

[0046] In addition, the following supplementary notes are disclosed regarding the above-described embodiment.

[0047] (Appendix 1) A communication terminal that performs sidelink communication with another communication terminal, receiving means for receiving a reference signal included in the sidelink communication; a calculation means for calculating a predetermined index based on the reference signal; a transmitting means for transmitting feedback information including the predetermined indicator to the other communication terminal when a cast type included in the control information received through the side link communication is a group cast; A communication terminal comprising:

[0048] (Appendix 2) A communication terminal that performs sidelink communication with another communication terminal, a transmitting means for transmitting control information including information indicating that the cast type is group cast and a reference signal to the other communication terminal through the side link communication; receiving means for receiving feedback information including a predetermined indicator included in the sidelink communication from the other communication terminal; A communication terminal comprising:

[0049] (Appendix 3) The reference signal is a Channel state information-reference signal. 3. A communication terminal according to claim 1 or 2.

[0050] (Appendix 4) The predetermined indicator is a precoding matrix index (PMI), a signal-to-interference-and-noise ratio (SINR), a signal quality indicator (CQI), or a received signal strength indicator (RSSI). 3. A communication terminal according to claim 1 or 2.

[0051] (Appendix 5) The feedback information includes information for identifying a group that transmits and receives the feedback information. 3. A communication terminal according to claim 1 or 2.

[0052] (Appendix 6) The feedback information includes information for identifying a terminal in a group that transmits and receives the feedback information. 3. A communication terminal according to claim 1 or 2.

[0053] (Appendix 7) The transmitting means is characterized in that, when receiving the feedback information, the transmitting means performs precoding setting based on the feedback information. 2. A communications terminal as described in Appendix 2.

[0054] (Appendix 8) The transmitting means, when receiving the feedback information, sets transmission power based on the feedback information. 2. A communications terminal as described in Appendix 2.

[0055] (Appendix 9) The transmitting means is characterized in that, when receiving the feedback information, the transmitting means performs beamforming setting of the terminal based on the feedback information. 2. A communications terminal as described in Appendix 2.

[0056] (Appendix 10) The control information is information of SCI (Sidelink Control Information) transmitted on PSSCH (Physical Sidelink Shared Channel), 3. A communication terminal according to claim 1 or 2.

[0057] (Appendix 11) A communication method performed by a communication terminal that performs sidelink communication with another communication terminal, receiving a reference signal included in the sidelink communication; calculating a predetermined index based on the reference signal; transmitting feedback information including the predetermined indicator to the other communication terminals when the cast type included in the control information received through the side link communication is group cast; A communication method comprising:

[0058] (Appendix 12) A communication method performed by a communication terminal that performs sidelink communication with another communication terminal, transmitting control information including information indicating that a cast type is groupcast and a reference signal to the other communication terminal through the sidelink communication; receiving feedback information from the other communication terminal, the feedback information including a predetermined indicator and included in the sidelink communication; A communication method comprising:

[0059] (Appendix 13) A computer of a communication terminal that performs sidelink communication with another communication terminal, receiving a reference signal included in the sidelink communication; calculating a predetermined index based on the reference signal; transmitting feedback information including the predetermined indicator to the other communication terminals when the cast type included in the control information received through the side link communication is group cast; A program to execute.

[0060] (Appendix 14) A computer of a communication terminal that performs sidelink communication with another communication terminal, transmitting control information including information indicating that a cast type is groupcast and a reference signal to the other communication terminal through the sidelink communication; receiving feedback information from the other communication terminal, the feedback information including a predetermined indicator and included in the sidelink communication; A program to execute. [Explanation of symbols]

[0061] 101 Terminal A (UE-A) 102 Terminal B (UE-B) 103 Terminal C (UE-C) 104 Terminal D (UE-D) 201 Control Unit 202 Storage section 203 Reception quality measurement unit 204 Communication setting section 205 Feedback information generation unit 206 Feedback Information Processing Section 207 Radio Communication Department 208 Control Information Processing Unit

Claims

1. A communication terminal that performs sidelink communication with another communication terminal, receiving means for receiving a reference signal included in the sidelink communication; a calculation means for calculating a predetermined index based on the reference signal; a transmitting means for transmitting feedback information including the predetermined indicator to the other communication terminal when a cast type included in the control information received through the side link communication is a group cast; A communication terminal comprising:

2. A communication terminal that performs sidelink communication with another communication terminal, a transmitting means for transmitting control information including information indicating that the cast type is group cast and a reference signal to the other communication terminal through the side link communication; receiving means for receiving feedback information including a predetermined indicator included in the sidelink communication from the other communication terminal; A communication terminal comprising:

3. The reference signal is a Channel state information-reference signal.

3. The communication terminal according to claim 1 or 2.

4. The predetermined indicator is a precoding matrix index (PMI), a signal-to-interference-and-noise ratio (SINR), a signal quality index (CQI), or a received signal strength indicator (RSSI), 3. The communication terminal according to claim 1 or 2.

5. The feedback information includes information for identifying a group that transmits and receives the feedback information.

3. The communication terminal according to claim 1 or 2.

6. The feedback information includes information for identifying a terminal in a group that transmits and receives the feedback information.

3. The communication terminal according to claim 1 or 2.

7. The transmitting means is characterized in that, when receiving the feedback information, the transmitting means performs precoding setting based on the feedback information. The communication terminal according to claim 2.

8. The transmitting means, when receiving the feedback information, sets transmission power based on the feedback information. The communication terminal according to claim 2.

9. The transmitting means is characterized in that, when receiving the feedback information, the transmitting means performs beamforming setting of the terminal based on the feedback information. The communication terminal according to claim 2.

10. The control information is SCI (Sidelink Control Information) information transmitted on a PSSCH (Physical Sidelink Shared Channel), 3. The communication terminal according to claim 1 or 2.

11. A communication method performed by a communication terminal that performs sidelink communication with another communication terminal, receiving a reference signal included in the sidelink communication; calculating a predetermined index based on the reference signal; transmitting feedback information including the predetermined indicator to the other communication terminals when the cast type included in the control information received through the side link communication is group cast; A communication method comprising:

12. A communication method performed by a communication terminal that performs sidelink communication with another communication terminal, transmitting control information including information indicating that a cast type is groupcast and a reference signal to the other communication terminal through the sidelink communication; receiving feedback information from the other communication terminal, the feedback information including a predetermined indicator and included in the sidelink communication; A communication method comprising:

13. A computer of a communication terminal that performs sidelink communication with another communication terminal, receiving a reference signal included in the sidelink communication; calculating a predetermined index based on the reference signal; transmitting feedback information including the predetermined indicator to the other communication terminals when the cast type included in the control information received through the side link communication is group cast; A program to execute.

14. A computer of a communication terminal that performs sidelink communication with another communication terminal, transmitting control information including information indicating that a cast type is groupcast and a reference signal to the other communication terminal through the sidelink communication; receiving feedback information from the other communication terminal, the feedback information including a predetermined indicator and included in the sidelink communication; A program to execute.

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