Communication device, communication system, control method, and program

Abstract

Disclosed is a communication device characterized by comprising: a reception means for receiving a propagation path information report including an identifier that makes it possible to identify whether sub-band precoding or wideband precoding is suitable; an identification means that uses the identifier as a basis to identify whether sub-band precoding or wideband precoding is suitable; a generation means that performs precoding of transmission data in accordance with the identification result of the identification means; and a transmission means that transmits the transmission data generated by the generation means.

Description

Communication device, communication system, control method, and program

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

[0002] In wireless communications, there is a precoding technology that generates a signal that takes current propagation path information into account on the transmitting side to improve transmission efficiency. When precoding is performed between a base station conforming to the 3GPP (3rd Generation Partnership Project) (registered trademark) standard and a terminal, the base station determines instructions to the terminal depending on the communication status with the terminal, and then transmits a reference signal and a report instruction. The terminal then reports propagation path information to the base station using a report configuration based on this report instruction (see, for example, Patent Document 1). Based on this reported propagation path information, the base station transmits precoded data. Examples of report instructions include wideband, which represents a communication bandwidth (e.g., 20 MHz) using one piece of propagation path information, and subband, which divides the communication bandwidth into multiple bandwidths and represents multiple pieces of propagation path information. Furthermore, conventionally, precoding has not been performed in sidelink communications (communications between terminals) conforming to the 3GPP standard.

[0003] Japanese Patent Application Laid-Open No. 2021-100274

[0004] When implementing precoding communication in Sidelink communication (terminal-to-terminal communication) conforming to the 3GPP standard, the following problems arise. In terminal-to-terminal communication, unlike base station-to-terminal communication, both terminals may move. It takes a certain amount of time to determine the instructions to the terminal depending on the communication situation. However, in terminal-to-terminal communication, when the terminals move with each other, the communication situation may fluctuate more greatly than in base station-to-terminal communication. As a result, the determined instructions may not be appropriate at that time, and precoding performance may deteriorate.

[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 reporting of propagation path information in a manner that is less affected by terminal movement and reduces degradation of precoding performance.

[0006] A communication device according to one aspect of the present invention is characterized in that it comprises a receiving means for receiving a propagation path information report including an identifier that enables identification of whether the report is for subband precoding or wideband precoding, an identification means for identifying whether the report is for subband precoding or wideband precoding based on the identifier, a generating means for performing precoding of transmission data in accordance with the identification result of the identification means, and a transmitting means for transmitting the transmission data generated by the generating means.

[0007] According to one aspect of the present invention, it is possible to provide a mechanism that enables reporting of propagation path information in a manner that is less susceptible to the influence of terminal movement and reduces degradation of precoding performance.

[0008] FIG. 1 is a diagram showing an example of a reporting configuration of propagation path information for subbands. FIG. 2 is a diagram showing an example of a reporting configuration of propagation path information for widebands. FIG. 3 is a block diagram showing the configuration of a terminal in the first embodiment. FIG. 4 is a software functional block diagram of a terminal in the first embodiment. FIG. 5 is a diagram showing the configuration of a wireless communication system in the first embodiment. FIG. 6 is a diagram showing processing on a reference signal receiving side in the first embodiment. FIG. 7 is a diagram showing a reporting configuration of propagation path information for subbands in the first embodiment. FIG. 8 is a diagram showing a reporting configuration of propagation path information for widebands in the first embodiment. FIG. 9 is a diagram showing processing on a reference signal transmitting side in the first embodiment. FIG. 10 is a diagram showing processing on a reference signal transmitting side in the second embodiment.

[0009] Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. In the following description, the "number ***" in TS*** represents the number of the technical specification in the 3GPP standard.

[0010] As explained in the "Problem to be Solved by the Invention" section above, unlike base station-terminal communication, in terminal-to-terminal communication, both terminals may be moving. It takes a certain amount of time to determine the instructions to be given to the terminal depending on the communication situation. Note that terminal-to-terminal communication may be communication via a PC5 interface (e.g., an air interface between V2X (Vehicle to Everything) devices).

[0011] On the other hand, when the report content is configured autonomously instead of based on a report instruction, it does not take a relatively long time to configure the report content. Specifically, when the report content is configured autonomously based on a report instruction, it takes extra time from receiving the report instruction to receiving a reference signal for CSI measurement. Note that when based on a report instruction, a CSI (Channel State Information) report (an example of a propagation path information report) is implemented in an aperiodic format or a semi-persistent format. Also, when the report content is configured autonomously, the CSI report is implemented in a periodic format. However, with only the report of propagation path information in the current report configuration, it is not possible to identify whether the report is for a wideband or a subband. In particular, when the report configuration for a subband is as shown in FIG. 1 and the report configuration for a wideband is as shown in FIG. 2, the first two fields (CRI and Rank Indicator) are the same, so identification is not possible immediately. Note that CRI is an abbreviation for Channel state information-reference signal Resource Indicator.

[0012] Each of the embodiments described below aims to solve at least part of these problems.

[0013] First Embodiment FIG. 3 is a diagram showing an example of the functional configuration of a terminal 30 according to this embodiment.

[0014] Reference numeral 301 denotes a control unit that controls itself by executing a control program stored in a storage unit 302. Reference numeral 302 denotes a storage unit that stores the control program executed by the control unit 301 and various information such as communication parameters. Various operations described below are performed by the control unit 301 executing the control program stored in the storage unit 302. Reference numeral 303 denotes a radio receiving unit for receiving signals conforming to the 3GPP standard. Reference numeral 304 denotes a radio transmitting unit for transmitting signals conforming to the 3GPP standard.

[0015] Reference numeral 305 denotes an output unit that performs various outputs, and has a function that allows the output of visually recognizable information such as an LCD (Liquid Crystal Display) or an LED (Light Emitting Diode), or a sound output such as a speaker. The output unit 305 has a function that outputs at least one of visual information and sound information. Reference numeral 306 denotes an input unit that allows the user to perform various inputs or acquire sensor information.

[0016] FIG. 4 is a block diagram showing an example of the configuration of software functional blocks of the terminal 30. As shown in FIG.

[0017] 401 indicates the entire software function block.

[0018] A signal transmission unit 402 transmits signals conforming to the 3GPP standard.

[0019] A signal receiving unit 403 receives signals conforming to the 3GPP standard.

[0020] A data storage unit 404 stores and holds information such as the software itself and authentication information.

[0021] An input / output control unit 405 controls the output unit 305 and the input unit 306 .

[0022] A CSI table format identification unit 406 identifies the format in which the CSI for conveying channel information is configured. The CSI table format identification unit 406 identifies whether the CSI report is for subband precoding or wideband precoding based on table identification information (described later) included in the CSI report.

[0023] Reference numeral 407 denotes a precoding designation unit for designating whether to perform precoding processing based on a wideband CSI report, precoding processing based on a subband CSI report, or no precoding processing.

[0024] Reference numeral 408 denotes a precoding implementation unit that executes precoding in accordance with the designation by the precoding designation unit 407 .

[0025] Reference numeral 409 denotes a subband SINR determination unit for determining the SINR, which is the signal-to-interference-plus-noise ratio, for the subband currently used in communication. SINR is an abbreviation for Signal-to-Interference-plus-Noise Ratio.

[0026] Fig. 5 is a diagram showing an example of the configuration of a wireless communication system according to this embodiment. As shown in Fig. 5, the wireless communication system according to this embodiment has a terminal 30A and a terminal 30B. The terminal 30A and the terminal 30B perform Sidelink communication as defined by the 3GPP standard. In reality, many terminals may be present in the vicinity, but Fig. 5 shows only the configuration necessary for explaining this embodiment.

[0027] Hereinafter, we will mainly explain the case where terminal 30A first transmits a reference signal, then terminal 30B transmits a CSI report based on the received reference signal, and then terminal 30A performs precoding based on the received CSI report and transmits data.

[0028] FIG. 6 is a flowchart showing a reference signal receiving process performed in the terminal 30B of this embodiment.

[0029]

[0066] Here, when terminal 30B receives a reference signal ("YES" in S600) while waiting to receive a reference signal ("NO" in S600), it generates a CSI report (S601). If the CSI report is for subband precoding, it has a format as shown in FIG. 7, and the first field contains a value of 0x01 as table identification information. If the CSI report is for wideband precoding, it has a format as shown in FIG. 8, and the first field contains a value of 0x02 as table identification information.

[0030] The terminal 30B determines whether to use the table for subband precoding (whether to use the table for wideband precoding), and sets the table identification information to either 0x01 or 0x02 depending on the determination result. Note that the determination method at this time is arbitrary, and may be determined depending on the state of the radio wave propagation environment, for example.

[0031] The terminal 30B transmits the generated CSI report to the terminal 30A (S602). This enables the terminal 30A to determine whether the CSI report is for subband preceding or wideband preceding, based on only the first field.

[0032] FIG. 9 is a flowchart showing a reference signal transmitting process performed by the terminal 30A of this embodiment.

[0033] Here, terminal 30A first transmits a reference signal (S901) and waits until it receives a CSI report from terminal 30B (S902). At this time, terminal 30A transmits only a reference signal to terminal 30B, and does not transmit a report instruction.

[0034] If the determination result in S902 is Yes, the CSI table format identification section 406 is used to determine whether the table identification information of the CSI report includes 0x01 (S903).

[0035] If the determination result in S903 is Yes, the CSI report is for subband precoding, so precoding using information for subband precoding is performed (S904), and data is transmitted (S906).

[0036] If the determination result in S903 is No, precoding using the information for wideband precoding is performed (S905), and data is transmitted (S906).

[0037] The processes of S904 and S905 are performed by the precoding designation unit 407 designating whether subband precoding or wideband precoding is to be performed.

[0038] As a result, in terminal-to-terminal communications that comply with the 3GPP standard, it becomes possible to transmit appropriate CSI reports, thereby reducing degradation of precoding performance.

[0039] In this embodiment, the roles of the receiver and transmitter of the reference signal are separated, but the receiver processing and transmitter processing may be executed in parallel between the same terminals.

[0040] [Second Embodiment] In the second embodiment, the functional configuration of the terminal, the configuration of the software function blocks of the terminal, the configuration of the network, the processing on the reference signal receiving side, the format for subband precoding, and the format for wideband precoding are as shown in FIGS. 3 to 8 , similarly to the first embodiment.

[0041] 10 is a flowchart showing the processing on the reference signal transmission side performed by the terminal 30A of this embodiment. Here, the processing of steps S901, S902, and S903 is the same as in the first embodiment, so the same reference numerals are used and the description will be omitted.

[0042] If the judgment result in S903 is Yes, the subband SINR judgment unit 409 is used to judge whether the SINR value (an example of a value of a propagation path information report) of the subband currently being used in communication is 3 dB or more (an example of a predetermined value) (S1004).

[0043] If the determination result in S903 is No, the CSI table format identification section 406 is used to determine whether the table identification information of the CSI report includes 0x02 (S1005).

[0044] If the determination result in S1004 is Yes, precoding using the subband information is performed (S1006), and data is transmitted (S1009).

[0045] If the determination result in S1004 is No, precoding using wideband information is performed (S1007), and data is transmitted (S1009). This is possible because the report configuration of the propagation path information for the subband includes the propagation path information for the wideband.

[0046] If the determination result in S1005 is Yes, precoding using the wideband information is performed (S1007), and data is transmitted (S1009).

[0047] If the result of the determination in S1005 is No, it is decided not to perform precoding (S1008), and data is transmitted (S1009).

[0048] Note that steps S1005, S1007, and S1008 are processed by the precoding designation unit 407 designating whether to perform subband precoding, wideband precoding, or no precoding.

[0049] As described above, when the SINR of the subband currently in use is not good, i.e., when it is less than 3 dB in this embodiment, another method, i.e., wideband precoding is used in this embodiment, with the aim of improving transmission efficiency. Note that, although this embodiment describes using wideband precoding when the SINR of the subband currently in use is not good, a method that does not perform precoding may also be adopted.

[0050] In the first and second embodiments, a terminal that receives a reference signal autonomously transmits a CSI report, and at that time, the report includes an identifier of either wideband information or subband information. However, the CSI report may be transmitted not only after receiving the reference signal but also after receiving an instruction to transmit the CSI report. In this case, the CSI report may include an identifier of either wideband information or subband information. In the first and second embodiments, the identifier of the CSI report in communication between terminals has been described. However, in reality, mobile base stations are widespread, and the propagation path conditions between base stations and terminals may change frequently. Therefore, the identifier of the CSI report described in this embodiment is not limited to communication between terminals. It can also be applied to communication between base stations and terminals.

[0051] (Other Embodiments) In this embodiment, a recording medium storing software program code for implementing the above-described functions may be supplied to a system or device, and the computer (CPU, MPU) of the system or device may read and execute the program code stored on the recording medium. Note that CPU is an abbreviation for Central Processing Unit, and MPU is an abbreviation for Micro Processing Unit. In this case, the program code read from the storage medium itself implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes this embodiment. The functions can also be implemented by a circuit (e.g., an ASIC or FPGA) that implements one or more functions. Note that ASIC is an abbreviation for Application Specific Integrated Circuit, and FPGA is an abbreviation for Field Programmable Gate Array. Furthermore, by having a hardware circuit cooperate with a processor such as a CPU or MPU, it is possible to realize some or all of the various processes described in the above flowcharts.

[0052] Examples of storage media that can be used to supply the program code include flexible disks, hard disks, optical disks, magneto-optical disks, CD (Compact Disc)-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, etc. Also usable are ROMs (Read Only Memory), DVDs (Digital Versatile Discs), HDDs (Hard Disk Drives), SSDs (Solid State Drives), etc.

[0053] 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.

[0054] Furthermore, the program code read from the storage medium may be written to a memory provided in a function expansion board inserted into a computer or a function expansion unit connected to the computer, and a CPU provided in 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.

[0055] Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments.

[0056] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0057] This application claims priority based on Japanese Patent Application No. 2024-025123, filed February 22, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A communications device that communicates in accordance with the 3GPP (3rd Generation Partnership Project) standard, comprising: a receiving means for receiving a channel information report including an identifier that enables identification of whether the channel information report is for subband precoding or wideband precoding; an identifying means for identifying whether the channel information report is for subband precoding or wideband precoding based on the identifier; a generating means for performing precoding on transmission data in accordance with the identification result of the identifying means; and a transmitting means for transmitting the transmission data generated by the generating means.

2. The communication device according to claim 1, wherein the generating means performs precoding based on subband information when the propagation path information report includes a first identifier as the identifier.

3. The communication device according to claim 1, wherein the generating means performs precoding based on wideband information when the propagation path information report does not include a first identifier as the identifier.

4. The communication device according to claim 1, wherein the generating means performs precoding based on wideband information when the propagation path information report includes a second identifier as the identifier.

5. The communication device according to claim 1, characterized in that the generation means performs precoding based on wideband information when the channel state report includes a first identifier as the identifier and the value of the channel state report for the currently used subband is lower than a predetermined value.

6. The communication device according to claim 1, characterized in that the generation means does not perform precoding if the channel state report includes a first identifier as the identifier and the value of the channel state report for the currently used subband is lower than a predetermined value.

7. A communication device according to claim 1, characterized in that the transmitting means transmits data using a subband with relatively better propagation path characteristics when the propagation path information report includes a first identifier as the identifier and the value of the propagation path information report for the subband currently in use is lower than a predetermined value.

8. The communication device according to claim 1, wherein said receiving means receives said propagation path information report from another mobile communication device, and said transmitting means transmits said transmission data to said other communication device.

9. A communication device that performs communication in accordance with the 3GPP (3rd Generation Partnership Project) standard, comprising: a receiving means for receiving a reference signal related to CSI (Channel State Information); and a transmitting means for transmitting a channel information report that includes an identifier that enables identification of whether the channel information report is for subband precoding or wideband precoding.

10. The communication device according to claim 9, wherein the identifier is placed before a field indicating a Channel State Information-Reference Signal Resource Indicator (CRI).

11. The communication system according to claim 10, wherein the identifier is placed before a field indicating a Rank Indicator.

12. A communication system comprising: a first communication device which is a communication device according to any one of claims 1 to 8; and a second communication device which is a communication device according to claim 9, wherein the first communication device transmits a reference signal; and the second communication device transmits the propagation path information report to the first communication device in response to the reference signal.

13. A control method for controlling communications, comprising: a receiving step of receiving a propagation path information report including an identifier that enables identification of whether the report is for subband precoding or wideband precoding; an identifying step of identifying whether the report is for subband precoding or wideband precoding based on the identifier; a generating step of performing precoding on transmission data according to the identification result of the identifying step; and a transmitting step of transmitting the transmission data generated by the generating step.

14. A program for causing a computer to execute the following steps: a receiving step of receiving a propagation path information report including an identifier that enables identification of whether the report is for subband precoding or wideband precoding; an identification step of identifying whether the report is for subband precoding or wideband precoding based on the identifier; a generation step of performing precoding on transmission data according to the identification result of the identification step; and a transmission step of transmitting the transmission data generated by the generation step.

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