WO2020144826A1

WO2020144826A1 - Communication device, wireless communication system, and communication control method

Info

Publication number: WO2020144826A1
Application number: PCT/JP2019/000582
Authority: WO
Inventors: ジヤンミンウー; 寛青木
Original assignee: 富士通株式会社
Priority date: 2019-01-10
Filing date: 2019-01-10
Publication date: 2020-07-16

Abstract

This communication device has: a determination unit that determines an offset amount for changing the ratio of the size of a first resource pool usable for data transmission by each communication device in a group comprising a plurality of communication devices to the size of a second resource pool usable for data re-transmission by each communication device; and a transmission unit that transmits control information designating the determined offset amount to the communication devices constituting the group.

Description

Communication device, wireless communication system, and communication control method

The present invention relates to a communication device, a wireless communication system, and a communication control method.

In the current network, the traffic of mobile terminals (smartphones and feature phones) accounts for most of the network resources. Also, the traffic used by mobile terminals tends to continue to grow.

On the other hand, according to the development of IoT (Internet of things) services (for example, monitoring systems for transportation systems, smart meters, devices, etc.), it is required to support services with various requirements. Therefore, in the communication standard of the next generation (for example, 5G (fifth generation mobile communication)), in addition to the standard technology of 4G (fourth generation mobile communication), further higher data rate, larger capacity, and lower delay are provided. The technology to realize this is required. Regarding the fifth generation communication standard, technical studies are being conducted by a working group of 3GPP (for example, TSG-RAN WG1, TSG-RAN WG2, etc.).

As mentioned above, in order to support a wide variety of services, 5G is classified into eMBB (Enhanced Mobile BroadBand), Massive MTC (Machine Type Communications), and URLLC (Ultra-Reliable and Low Latency Communication). Support for many use cases is envisioned.

Also, the 3GPP working group is discussing D2D (Device to Device) communication and V2X (Vehicle to Everything) communication. D2D communication and V2X communication are performed using, for example, a side link channel. Further, as the V2X communication, for example, there are V2V (Vehicle to Vehicle) communication, V2P (Vehicle to Pedestrian) communication, V2I (Vehicle to Infrastructure) communication, and the like. V2V communication indicates communication between vehicles, V2P communication indicates communication between a vehicle and a pedestrian (Pedestrian), and V2I communication indicates communication between a vehicle and road infrastructure such as a sign.

Also, in V2X communication, a repetition of the same data has been introduced as a method of ensuring the reliability required for the next-generation communication standards.

By the way, when a repetition is performed in V2X communication, the probability that each terminal device retransmits data increases as the number of terminal devices located within the communicable range increases. When the probability that each terminal device retransmits data increases, a large amount of resources are consumed from the resource pool that each terminal device can use to retransmit data. Here, in the V2X communication, the ratio of the size of the resource pool that each terminal device can use to transmit data to the size of the resource pool that each terminal device can use to retransmit data is preset and fixed. Is common. Therefore, if a large amount of resources are consumed from the resource pool that can be used by each terminal device for data retransmission, the resource pool may be exhausted.

In V2X communication, if the resource pool that can be used for data retransmission is exhausted, data may not be retransmitted by each terminal device, and as a result, the reliability of communication decreases.

The disclosed technology aims to provide a communication device, a wireless communication system, and a communication control method capable of improving the reliability of communication.

According to one aspect of the communication device disclosed in the present application, the size of a first resource pool that can be used by each communication device of a group including a plurality of communication devices for data transmission, and the communication device retransmits data. A determination unit that determines an offset amount that changes the ratio with the size of the second resource pool that can be used for the above, and control information that specifies the determined offset amount is transmitted to a plurality of communication devices that configure the group. And a transmitter.

According to one aspect of the communication device disclosed in the present application, there is an effect that communication reliability can be improved.

FIG. 1 is a diagram illustrating a configuration example of a wireless communication system according to an embodiment. FIG. 2 is a diagram illustrating an example of a functional configuration of the management terminal device according to the embodiment. FIG. 3 is a diagram illustrating an example of offset amount determination according to the embodiment. FIG. 4 is a diagram illustrating an example of the functional configuration of the terminal device according to the embodiment. FIG. 5 is a diagram illustrating an example of data retransmission according to the embodiment. FIG. 6 is a flowchart showing an offset amount designating method according to the embodiment. FIG. 7 is a flowchart illustrating the resource pool adjustment method according to the embodiment. FIG. 8 is a flowchart showing the data retransmission method according to the embodiment. FIG. 9 is a flowchart showing a retransmission resource designating method according to the embodiment. FIG. 10 is a diagram illustrating a hardware configuration example of the management terminal device. FIG. 11 is a diagram illustrating a hardware configuration example of a terminal device.

Hereinafter, embodiments of the communication device, the wireless communication system, and the communication control method disclosed in the present application will be described in detail with reference to the drawings. The disclosed technology is not limited to the embodiments.

FIG. 1 is a diagram illustrating a configuration example of a wireless communication system 1 according to an embodiment. The wireless communication system 1 illustrated in FIG. 1 includes a management terminal device 10, a terminal device 20, and a terminal device 30. The terminal device 20 and the terminal device 30 belong to a group managed by the management terminal device 10. The management terminal device 10 is a terminal device representing a group, and is also called a CH (Cluster Header). The management terminal device 10, the terminal device 20, and the terminal device 30 may be terminal devices located in a range where they can communicate with each other, and are, for example, automobiles. The management terminal device 10 and the terminal device 20 are connected by a wireless link 40, the terminal device 20 and the terminal device 30 are connected by a wireless link 50, and the terminal device 30 and the management terminal device 10 are They are connected by a wireless link 60. The

wireless links

40, 50, 60 are called side links or PC5 links. In addition, in FIG. 1, the terminal device 20 and the terminal device 30 are illustrated as belonging to the group managed by the management terminal device 10, but other terminal devices not shown also belong to the group managed by the management terminal device 10. I shall. Further, although FIG. 1 shows an example in which the management terminal device 10 is an automobile, the management terminal device 10 may be a gNB as a next-generation NodeB, an RSU (Road Side Unit), or the like.

Each terminal device in the group can communicate with each other, and when transmitting data, multicast (group cast) with all the terminal devices in the group as destinations. Therefore, the data transmitted by one terminal device in the group can be received by all the other terminal devices in the group. In addition, each terminal device in the group executes a repetition of repeatedly transmitting the same data. For example, when data to be transmitted is generated, the terminal device 20 includes a plurality of resources included in a first resource pool (hereinafter referred to as “first RP”) that can be used by each terminal device of the group for data transmission. A resource used for data transmission is autonomously selected from the resources. Then, the terminal device 20 transmits the data to the terminal device 30 using the selected resource. The terminal device 30 transmits ACK (ACKnowledgement)/NACK (Negative ACKnowledgement) according to the data reception status. The management terminal device 10 (and/or the terminal device 20) receives the ACK/NACK transmitted from the terminal device 30. If necessary, the data is retransmitted under the initiative of the management terminal apparatus 10. That is, the terminal device 20 receives the SCI (Sidelink Control Information) that specifies the retransmission resource, which is transmitted from the management terminal device 10. The retransmission resource is selected by the management terminal device 10 from a plurality of resources included in a second resource pool (hereinafter referred to as “second RP”) that can be used by each end device of the group for data retransmission. Is a resource that is Then, the terminal device 20 retransmits the data to the terminal device 30, using the retransmission resource designated by the SCI.

The management terminal device 10 is an offset that changes the ratio between the size of the first RP that can be used by each terminal device of the group for data transmission and the size of the second RP that can be used by each terminal device for data retransmission. Determine the amount. At this time, the management terminal device 10 determines the offset amount so that the size of the first RP is reduced and the size of the second RP is increased. That is, the management terminal device 10 sets the size of the first RP so that the second RP is not exhausted even when each terminal device of the group consumes a large amount of resources from the second RP for data retransmission. An offset amount that changes the ratio with the size of the second RP is determined. Then, the management terminal device 10 transmits the SCI designating the determined offset amount to the plurality of terminal devices forming the group.

Each terminal device in the group adjusts the size of the first RP and the size of the second RP based on the offset amount determined by the management terminal device 10. For example, the terminal device 20 receives the SCI designating the offset amount. Then, the terminal device 20 adjusts the size of the first RP and the size of the second RP based on the offset amount designated by the SCI.

As described above, in the wireless communication system 1, the management terminal device 10 controls the size of the first RP that each terminal device of the group can use to transmit data and the second RP that each terminal device can use to retransmit data. The offset amount that changes the ratio with the size of the RP is dynamically determined. This reduces the possibility that the second RP will be exhausted even when each terminal device in the group consumes a large amount of resources from the second RP for data retransmission. As a result, it is possible to avoid the situation where data is not retransmitted from each terminal device of the group due to the exhaustion of the second RP, and the reliability of communication can be improved.

FIG. 2 is a diagram illustrating an example of a functional configuration of the management terminal device 10 according to the embodiment. As illustrated in FIG. 2, the management terminal device 10 includes an SCI receiving unit 11, a reception quality determining unit 12, a retransmission resource selecting unit 13, an offset amount determining unit 14, and an SCI transmitting unit 15.

The SCI receiving unit 11 receives the SCI indicating the position of the resource (hereinafter referred to as “initial resource”) used for data transmission (initial transmission) by each terminal device of the group. When each terminal device (for example, the terminal device 20) of the group transmits the data, the SCI indicating the position of the initial resource is used together with the data and another terminal device (for example, the terminal device) to which the data is transmitted. Device 30). At this time, the SCI indicating the position of the initial resource reaches not only the other terminal device of the transmission destination but also the management terminal device 10. When the SCI indicating the position of the initial resource reaches the management terminal device 10, the SCI receiving unit 11 receives the SCI.

The reception quality judgment unit 12 judges whether or not the reception quality of the data in another terminal device, which is the destination of the data, is good, using the SCI indicating the position of the initial resource. For example, the reception quality determination unit 12 determines whether or not the reception quality is good by confirming ACK/NACK, which is a result of receiving data, which is returned in a group cast from another terminal device of the transmission destination. To do.

When the reception quality determination unit 12 determines that the reception quality of another terminal device that is a data transmission destination is not good, the retransmission resource selection unit 13 selects from among the plurality of resources included in the second RP. , Select a resend resource.

In addition, the retransmission resource selection unit 13 is based on the offset amount when the offset amount determination unit 14 to be described later determines the offset amount for changing the ratio of the size of the first RP to the size of the second RP. Then, the size of the first RP and the size of the second RP are adjusted. Then, the retransmission resource selection unit 13 selects a retransmission resource from the plurality of resources included in the adjusted second RP.

Further, when there is no resource to be selected as a retransmission resource in the second RP, the retransmission resource selection unit 13 transmits the SCI for notifying the exhaustion of the second RP to the plurality of terminal devices forming the group. ..

The offset amount determination unit 14 determines the offset amount for changing the ratio between the size of the first RP and the size of the second RP. Specifically, the offset amount determination unit 14 monitors the number of the plurality of terminal devices forming the group, and performs the offset so that the size of the second RP increases as the number of the plurality of terminal devices increases. Determine the amount. The offset amount is determined at a predetermined timing. For example, when the time division multiplexing (TDM) method of temporally dividing the transmission section is applied to the wireless communication system 1, the offset amount is determined at the timing when each transmission section is started. To be done.

FIG. 3 is a diagram illustrating an example of offset amount determination according to the embodiment. FIG. 3 is a diagram illustrating the determination of the offset amount performed when the TDM method is applied to the wireless communication system 1. In the example of FIG. 3, the first RP that can be used by each terminal device of the group for data transmission (initial transmission) is indicated by the shaded area, and the second RP that can be used by each terminal device of the group for data retransmission. The RP is indicated by the horizontal line area. Further, in the example of FIG. 3, it is assumed that the preset size of the first RP and the preset size of the second RP are Δ _a and Δ _d , respectively.

The offset amount determination unit 14 determines the size of the first RP and the second RP according to the number of a plurality of terminal devices forming a group at the timing when each transmission section (transmission sections #1 to #3) is started. Determine the amount of RP size offset. For example, the offset amount determination unit 14 determines the offset amount so that the size of the second RP increases because the number of the plurality of terminal devices forming the group increases at the timing when the transmission section #1 starts. To do. That is, the offset amount determining unit 14 changes the ratio between the size of the first RP and the size of the second RP from Δ _a /Δ _d to (Δ _a −Δ ₁ )/(Δ _d +Δ ₁ ). Determine the quantity Δ ₁ . Then, the offset amount determination unit 14 sets the offset amount so that the size of the second RP further increases because the number of the plurality of terminal devices forming the group increases at the timing when the transmission section #2 starts. decide. That is, the offset amount determining unit 14 changes the ratio between the size of the first RP and the size of the second RP to (Δ _a −Δ ₂ )/(Δ _d +Δ ₂ ), and the offset amount Δ ₂ (>Δ ₁ ) is determined. Then, the offset amount determination unit 14 determines the offset amount so that the size of the second RP decreases because the number of the plurality of terminal devices forming the group has decreased at the timing when the transmission section #3 is started. To do. That is, the offset amount determining unit 14 changes the ratio between the size of the first RP and the size of the second RP to (Δ _a −Δ ₃ )/(Δ _d +Δ ₃ ), and the offset amount Δ ₃ (<Δ ₂ ) is determined.

In this way, the offset amount determination unit 14 dynamically changes the offset amount for changing the ratio between the size of the first RP and the size of the second RP according to the number of the plurality of terminal devices forming the group. To make a decision, the likelihood of the second RP being depleted is reduced. As a result, a situation in which data is not retransmitted from each terminal device in the group due to exhaustion of the second RP is avoided, and communication reliability can be improved.

In addition, in the example of FIG. 3, the determination of the offset amount based on the TDM method is shown. However, even when the frequency division multiplexing (FDM) method is adopted, the offset amount is dynamically changed. Can be determined.

Return to the explanation of FIG. The SCI transmission unit 15 transmits the SCI designating the offset amount determined by the offset amount determination unit 14 to the plurality of terminal devices forming the group.

Further, the SCI transmission unit 15 transmits the SCI designating the retransmission resource selected by the retransmission resource selection unit 13 to each terminal device which is the data transmission source. In the present embodiment, the SCI transmitter 15 transmits to the terminal device 20 which is the source of the data.

In the above description, the SCI receiving unit 11 and the SCI transmitting unit 15 transmit and receive the SCI, but the disclosed technology is not limited to this. For example, the management terminal device 10 may include a control information receiving unit (or a receiving unit) and a control information transmitting unit (a transmitting unit) instead of the SCI receiving unit 11 and the SCI transmitting unit 15. In this case, the control information receiving unit and the control information transmitting unit transmit/receive other control information different from SCI.

FIG. 4 is a diagram illustrating an example of a functional configuration of the terminal device 20 according to the embodiment. As shown in FIG. 4, the terminal device 20 includes a resource selection unit 21, an SCI transmission unit 22, a data transmission unit 23, a buffer unit 24, an SCI reception unit 25, a repeated transmission unit 26, an SCI reception unit 27, and an RP adjustment unit 28. Have.

When the data to be transmitted is generated, the resource selection unit 21 autonomously selects the resource used by the terminal device 20 for data transmission from the plurality of resources included in the first RP.

In addition, when the sizes of the first RP and the second RP are adjusted by the RP adjusting unit 28, which will be described later, the resource selecting unit 21 selects the terminal from the plurality of resources included in the adjusted first RP. The device 20 autonomously selects the resource used for data transmission. The resource selected by the resource selection unit 21 corresponds to the above initial resource.

The SCI transmission unit 22 transmits the SCI indicating the position of the initial resource selected by the resource selection unit 21 to the terminal device 30. The SCI indicating the position of the initial resource reaches not only the terminal device 30 but also the management terminal device 10.

The data transmission unit 23 uses the initial resource selected by the resource selection unit 21 to transmit data to the terminal device 30.

The buffer unit 24 is a storage area for temporarily storing the SCI transmitted by the SCI transmitting unit 22 and the data transmitted by the data transmitting unit 23.

The SCI receiving unit 25 receives the SCI transmitted by the management terminal device 10 and designating the retransmission resource.

The repetitive transmission unit 26 retransmits the data to the terminal device 30, using the retransmission resource designated by the SCI. Specifically, the repetitive transmission unit 26 transmits the data stored in the buffer unit 24 to the terminal device 30, using the retransmission resource designated by the SCI. Then, the repetitive transmission unit 26 rewrites the position of the initial resource indicated by the SCI stored in the buffer unit 24 to the position of the retransmission resource, and transmits the rewritten SCI together with the data to the terminal device 30.

In addition, the repetitive transmission unit 26 is notified of the exhaustion of the retransmission resource by the SCI when the SCI designating the retransmission resource is not received within a predetermined time after the initial transmission of the data by the data transmission unit 23. In that case, a new resource is autonomously selected from the plurality of resources included in the first RP. Then, the repetitive transmission unit 26 retransmits the data using the selected new resource.

FIG. 5 is a diagram illustrating an example of data retransmission according to the embodiment. FIG. 5 is a diagram illustrating data retransmission performed when the TDM method is applied to the wireless communication system 1. In the example of FIG. 5, the first RP that each terminal device of the group can use for data transmission (initial transmission) is indicated by the shaded area, and the second RP that each terminal device of the group can use for data retransmission The RP is indicated by the horizontal line area.

The data transmission unit 23 transmits data to the terminal device 30 in the transmission section #1 by using the initial resource 111 selected from the plurality of resources included in the first RP by the resource selection unit 21. Then, the repetitive transmission unit 26 transmits the data to the terminal device 30 in the transmission section #1 using the retransmission resource 112 designated by the SCI. The retransmission resource 112 is selected by the management terminal device 10 from a plurality of resources included in the second RP.

Then, the data transmission unit 23 transmits the data to the terminal device 30 in the transmission section #2 by using the initial resource 121 selected from the plurality of resources included in the first RP by the resource selection unit 21. To do. However, in the transmission section #2, the SCI designating the retransmission resource is not received by the SCI reception unit 25 until the predetermined time has elapsed from the initial transmission of the data by the data transmission unit 23. Alternatively, the SCI reception unit 25 notifies the repeated transmission unit 26 that the second RP is exhausted. For example, when the second RP is exhausted, the retransmission resource is not selected from the second RP in the management terminal device 10, and thus the SCI designating the retransmission resource is not transmitted. Further, even when the management terminal apparatus 10 fails to decode the SCI indicating the position of the initial resource or the ACK/NACK which is the reception result of the data, the management terminal apparatus 10 does not select the retransmission resource from the second RP. The SCI designating the retransmission resource is not transmitted. Therefore, the SCI designating the retransmission resource is not received by the SCI receiving unit 25. Alternatively, when the second RP is exhausted, the management terminal device 10 transmits information that the retransmission resource is not selected from the second RP by the SCI. Therefore, the SCI designating the retransmission resource is not acquired by the SCI receiving unit 25. Therefore, the repetitive transmission unit 26 does not receive the SCI designating the retransmission resource until the predetermined time elapses from the initial transmission of the data by the data transmission unit 23, or when the SCI depletes the second RP. When notified, a new resource is autonomously selected from a plurality of resources included in the first RP. In the example of FIG. 3, the repetitive transmission unit 26 autonomously selects the new resource 122 from the plurality of resources included in the first RP in the transmission section #3. Then, the repetitive transmission unit 26 retransmits the data to the terminal device 30 using the selected new resource 122. Accordingly, even when the second RP is exhausted, the data is retransmitted using the new resource 122 selected from the first RP, so that the reliability of communication can be improved.

Return to the explanation of FIG. The SCI receiving unit 27 receives the SCI transmitted by the management terminal device 10 and designating the offset amount.

The RP adjusting unit 28 adjusts the size of the first RP and the size of the second RP based on the offset amount designated by the SCI.

Next, a method of specifying the offset amount by the management terminal device 10 according to the embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing an offset amount designating method according to the embodiment.

The offset amount determination unit 14 determines the offset amount for changing the ratio between the size of the first RP and the size of the second RP when a predetermined timing arrives (Yes in step S11) (step S12). The predetermined timing is, for example, the timing at which each transmission section of the TDM system is started when the TDM system is applied to the wireless communication system 1.

The SCI transmission unit 15 transmits the SCI designating the offset amount determined by the offset amount determination unit 14 to a plurality of terminal devices including the terminal device 20 and the terminal device 30 (step S13).

As described above, the management terminal device 10 has a ratio between the size of the first RP that can be used by each terminal device of the group for data transmission and the size of the second RP that can be used by each terminal device for retransmission of data. The amount of offset for changing is dynamically determined. This reduces the possibility that the second RP will be exhausted even when each terminal device in the group consumes a large amount of resources from the second RP for data retransmission. As a result, it is possible to avoid the situation where data is not retransmitted from each terminal device of the group due to the exhaustion of the second RP, and the reliability of communication can be improved.

Next, a resource pool adjusting method by the terminal device 20 according to the embodiment will be described with reference to FIG. 7. FIG. 7 is a flowchart illustrating the resource pool adjustment method according to the embodiment.

The RP adjusting unit 28 waits when the SCI designating the offset amount for changing the ratio between the size of the first RP and the size of the second RP is not received by the SCI receiving unit 27 (No in step S21). When the SCI designating the offset amount is received by the SCI receiving unit 27 (Yes in step S21), the RP adjusting unit 28 determines the size of the first RP and the second RP based on the offset amount designated by the SCI. The size is adjusted (step S22).

Next, a data retransmission method by the terminal device 20 according to the embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing the data retransmission method according to the embodiment.

When the data to be transmitted is generated, the resource selection unit 21 autonomously selects the resource used by the terminal device 20 for data transmission from the plurality of resources included in the first RP (step S31). Here, when the size of the first RP and the size of the second RP are adjusted by the RP adjusting unit 28, the resource selecting unit 21 selects from among the plurality of resources included in the adjusted first RP. The terminal device 20 autonomously selects a resource used for data transmission.

The data transmission unit 23 transmits data to the terminal device 30 using the resource (that is, the initial resource) selected by the resource selection unit 21 (step S32).

If the SCI designating the resending resource is received by the SCI receiving unit 25 (Yes in step S33), the repeat transmitting unit 26 retransmits the data using the resending resource designated by the SCI (step S34).

On the other hand, when the SCI designating the retransmission resource is not received by the SCI receiving unit 25 (No in step S33), the repeat transmitting unit 26 determines whether or not a predetermined time has elapsed from the initial transmission of the data in step S32 (step S35). ). When the predetermined time has not passed from the initial transmission of the data (No in step S35), the repeat transmitting unit 26 returns the process to step S33 and confirms whether the SCI designating the retransmission resource is received by the SCI receiving unit 25. To do.

When the SCI designating the retransmission resource is not received within a predetermined time after the initial transmission of the data (No in step S33), the repetitive transmission unit 26 selects a new resource from among the plurality of resources included in the first RP. The resource is selected autonomously (step S36). In addition, when the SCI notifies the exhaustion of the second RP until the predetermined time elapses from the initial transmission of the data, the repetitive transmission unit 26 selects from among the plurality of resources included in the first RP. New resources may be selected autonomously. Then, the repetitive transmission unit 26 retransmits the data using the selected new resource (step S37).

Next, a retransmission resource specifying method by the management terminal device 10 according to the embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing a retransmission resource designating method according to the embodiment.

The SCI receiving unit 11 receives the SCI indicating the position of the resource (that is, the initial resource) used for data transmission (initial transmission) by each terminal device of the group (step S41).

The reception quality determination unit 12 uses the SCI indicating the position of the initial resource to determine whether or not the reception quality of data in another terminal device (for example, the terminal device 30) of the data transmission destination is good ( Step S42). When the reception quality determination unit 12 determines that the reception quality of the other terminal device of the data transmission destination is good (Yes in step S42), the retransmission resource selection unit 13 stops the selection of the retransmission resource and ends the process. To do.

On the other hand, when the reception quality determination unit 12 determines that the reception quality at the other terminal device of the data transmission destination is not good (No in step S42), the retransmission resource selection unit 13 performs the following processing. That is, the retransmission resource selection unit 13 determines whether or not the offset amount determination unit 14 has determined the offset amount for changing the ratio between the size of the first RP and the size of the second RP (step S43). When the offset amount is determined by the offset amount determining unit 14 (Yes in step S43), the retransmission resource selecting unit 13 adjusts the size of the first RP and the size of the second RP based on the offset amount ( Step S44). On the other hand, when the offset amount is not determined by the offset amount determining unit 14 (No in step S43), the retransmission resource selecting unit 13 performs the process without adjusting the size of the first RP and the size of the second RP. Proceed to S45.

Then, the retransmission resource selection unit 13 selects a retransmission resource from the plurality of resources included in the second RP (step S45). At this time, when there is no resource to be selected as a retransmission resource in the second RP, the retransmission resource selection unit 13 transmits the SCI for notifying the exhaustion of the second RP to the plurality of terminal devices forming the group. To do.

The SCI transmission unit 15 transmits the SCI designating the retransmission resource selected by the retransmission resource selection unit 13 to each terminal device (for example, the terminal device 20) that is the data transmission source (step S46).

As described above, according to the present embodiment, the management terminal device 10 allows the terminal devices of the group to use the first RP size that each terminal device can use for data transmission and the second RP that each terminal device can use for data retransmission. The amount of offset for changing the ratio with the size of is dynamically determined. This reduces the possibility that the second RP will be exhausted even when each terminal device in the group consumes a large amount of resources from the second RP for data retransmission. As a result, it is possible to avoid the situation where data is not retransmitted from each terminal device of the group due to the exhaustion of the second RP, and the reliability of communication can be improved.

In the above embodiment, the example in which the SCI designating the offset amount is transmitted to the plurality of terminal devices forming the group has been described, but the offset amount may not necessarily be designated by the SCI. For example, the offset amount may be specified using RRC (Radio Resource Control). Further, both the control by RRC (Long-term control) and the control by SCI (Short-term control) may be used or may be used properly.

[Hardware configuration]
The management terminal device 10 according to the above embodiment can be realized, for example, by the following hardware configuration. FIG. 10 is a diagram illustrating a hardware configuration example of the management terminal device 10. As illustrated in FIG. 10, the management terminal device 10 includes a CPU (Central Processing Unit) 10a, a memory 10b, and an RF (Radio Frequency) circuit 10c having an antenna A1. The memory 10b is composed of, for example, RAM such as SDRAM (Synchronous Dynamic Random Access Memory), ROM (Read Only Memory), and flash memory. The SCI reception unit 11, the reception quality determination unit 12, the retransmission resource selection unit 13, the offset amount determination unit 14, and the SCI transmission unit 15 are realized by, for example, the CPU 10a and the RF circuit 10c.

Further, the terminal device 20 according to the above embodiment can be realized by, for example, the following hard wafer configuration. FIG. 11 is a diagram illustrating a hardware configuration example of the terminal device 20. As shown in FIG. 11, the terminal device 20 has a CPU 20a, a memory 20b, and an RF circuit 20c having an antenna A1. The memory 30b is composed of, for example, RAM such as SDRAM, ROM, and flash memory. The buffer unit 24 is realized by, for example, the memory 30b. The resource selection unit 21, the SCI transmission unit 22, the data transmission unit 23, the SCI reception unit 25, the repeated transmission unit 26, the SCI reception unit 27, and the RP adjustment unit 28 are realized by, for example, the CPU 20a and the RF circuit 20c.

1 Radio Communication System 10 Management Terminal Device 11 SCI Receiving Unit 12 Reception Quality Determining Unit 13 Retransmission Resource Selecting Unit 14 Offset Amount Determining Unit 15 SCI Transmitting Unit 20 Terminal Device 21 Resource Selecting Unit 22 SCI Transmitting Unit 23 Data Transmitting Unit 24 Buffering Unit 25 SCI receiver 26 Repeat transmitter 27 SCI receiver 28 RP adjuster

Claims

A size of a first resource pool that can be used by each communication device of a group composed of a plurality of communication devices for data transmission, and a size of a second resource pool that can be used by each communication device for retransmission of data; A determination unit that determines the offset amount for changing the ratio,
A transmission unit that transmits control information that specifies the determined offset amount to a plurality of communication devices that configure the group,
A communication device comprising:
The determination unit monitors the number of a plurality of communication devices forming the group, and determines the offset amount so that the size of the second resource pool increases as the number of the plurality of communication devices increases. The communication device according to claim 1, wherein the communication device comprises:
When each of the communication devices transmits data to another communication device by using a resource selected from a plurality of resources included in the first resource pool, A determination unit that determines whether or not the reception quality is good,
When it is determined that the reception quality of the data is not good, a retransmission resource that is a resource used by each of the communication devices to retransmit data is selected from a plurality of resources included in the second resource pool. A selection part,
Further has
The communication device according to claim 1, wherein the transmission unit further transmits control information designating a selected retransmission resource to each of the communication devices that are the transmission sources of the data.
When the offset amount is determined, the selection unit adjusts the size of the first resource pool and the size of the second resource pool based on the offset amount, and adjusts the second resource. The communication device according to claim 3, wherein the retransmission resource is selected from a plurality of resources included in a pool.
A size of a first resource pool that can be used by each communication device of a group composed of a plurality of communication devices for data transmission, and a size of a second resource pool that can be used by each communication device for retransmission of data; A receiving unit that receives control information that specifies an offset amount for changing the ratio,
An adjusting unit that adjusts the size of the first resource pool and the size of the second resource pool based on the offset amount designated by the control information;
A communication device comprising:
A selection unit that autonomously selects a resource used by the own device for data transmission from a plurality of resources included in the first resource pool,
A transmitter that transmits data using the selected resource,
A receiving unit for receiving control information designating a retransmission resource, which is a resource selected from a plurality of resources included in the second resource pool,
A repetitive transmission unit that retransmits data using a retransmission resource designated by the control information,
Further has
When the size of the first resource pool and the size of the second resource pool are adjusted, the selecting unit selects, from among a plurality of resources included in the adjusted first resource pool, its own device. The communication device according to claim 5, wherein a resource used for transmitting data is autonomously selected.
The repetitive transmission unit receives the second resource pool when the control information designating the retransmission resource is not received within a predetermined time after the initial transmission of the data or by SCI (Sidelink Control Information). Is notified of the depletion of a resource, a new resource is autonomously selected from a plurality of resources included in the first resource pool, and data is retransmitted using the new resource. The communication device according to claim 6.
A wireless communication system having a first communication device and a second communication device,
The first communication device is
The size of a first resource pool that can be used by each communication device of a group including a plurality of communication devices including the first communication device and the second communication device for data transmission, and the size of each communication device A determination unit that determines an offset amount that changes the ratio with the size of the second resource pool that can be used for retransmission of
A transmission unit that transmits control information that specifies the determined offset amount to a plurality of communication devices that configure the group,
Have
The second communication device is
A receiver for receiving the control information,
An adjusting unit that adjusts the size of the first resource pool and the size of the second resource pool based on the offset amount designated by the control information;
A wireless communication system comprising:
A size of a first resource pool that can be used by each communication device of a group composed of a plurality of communication devices for data transmission, and a size of a second resource pool that can be used by each communication device for retransmission of data; Determine the offset amount to change the ratio,
A communication control method comprising: transmitting control information designating the determined offset amount to a plurality of communication devices forming the group.