Wireless communication systems and wireless communication methods

Abstract

To improve the reliability for a broadcast communication with less overhead.SOLUTION: A radio communication device that transmits data to a plurality of terminals by a predetermined radio communication standard, executes: continuously broadcast-transmitting a plurality of data blocks; broadcast-transmitting first notification data as a notification for declaring that there is a data block failed in reception, to a first terminal that receives at least some of the plurality of data blocks after completion of the transmission of the plurality of data blocks; and retransmitting the data block indicated by second notification data in the case of receiving the second notification data indicating the data block failed in reception from one or more first terminals as a response to the first notification data.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] This disclosure relates to mobile communication.

Background Art

[0002] There is a technology in which a master device broadcasts information to a plurality of mobile terminals. For example, Non-Patent Document 1 discloses a standard specification (IEEE802.11aa) for distributing video frames.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

[0007] One embodiment of the present disclosure is: A wireless communication system comprising a first wireless communication device and a second wireless communication device, wherein the first wireless communication device receives a plurality of data blocks broadcast transmitted by the second wireless communication device according to a predetermined wireless communication standard, receives first notification data from the second wireless communication device which is a notification to declare that there are data blocks that have failed to be received and is broadcast transmitted after the transmission of the plurality of data blocks is completed, and if it fails to receive any of the plurality of data blocks, it transmits second notification data indicating the data block that failed to be received to the second wireless communication device in response to the first notification data, and the second wireless communication device broadcasts the plurality of data blocks in succession, broadcasts the first notification data after the transmission of the plurality of data blocks is completed, and retransmits the data block indicated by the second notification data when the second notification data is transmitted from the first wireless communication device in response to the first notification data.

[0008] One embodiment of the present disclosure is: A wireless communication method performed by a first wireless communication device and a second wireless communication device, wherein the first wireless communication device receives a plurality of data blocks broadcast transmitted by the second wireless communication device in accordance with a predetermined wireless communication standard, receives a first notification data from the second wireless communication device which is a notification to declare that there are data blocks that have failed to be received and is broadcast transmitted after the transmission of the plurality of data blocks is completed, and if the reception of any of the plurality of data blocks fails, transmits a second notification data indicating the data block that failed to be received to the second wireless communication device in response to the first notification data, and the second wireless communication device broadcasts the plurality of data blocks in succession, broadcasts the first notification data after the transmission of the plurality of data blocks is completed, and retransmits the data block indicated by the second notification data when the second notification data is transmitted from the first wireless communication device in response to the first notification data.

[0009] Other embodiments include a program for causing a computer to execute the above method, or a computer-readable storage medium that non-temporarily stores the program. [Effects of the Invention]

[0010] According to this disclosure, reliability for broadcast communications can be improved with minimal overhead. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic diagram of the communication system according to the first embodiment. [Figure 2] A diagram showing the components of an in-vehicle device. [Figure 3] An example of an IP packet sent from a server device. [Figure 4] A diagram showing the components of an access point. [Figure 5] Sequence diagram for explaining the data transmission method. [Figure 6] Flowchart of the processes performed by the in-vehicle device. [Figure 7] Flowchart of the processes performed by the in-vehicle device. [Figure 8] Flowchart of the processes performed by the access point. [Figure 9] Flowchart of the processes performed by the access point.

Mode for Carrying Out the Invention

[0012] There is a technology in which a master device broadcasts data to a plurality of mobile terminals using wireless communication. However, since broadcast unidirectionally transmits data, it does not guarantee that all the data is successfully received by a plurality of terminals. On the other hand, for example, there is also a wireless communication standard that adopts a mechanism (BlockAck) for transmitting an Ack for each series of data blocks in order to notify the transmission source of the failure to receive continuously transmitted data.

[0013] However, in such a mechanism, since all the terminals included in the group transmit an Ack, the overhead is large and the utilization efficiency of the wireless channel is poor. The wireless communication device according to the present disclosure solves such problems.

[0014] The wireless communication device according to the first aspect of the present disclosure is a wireless communication device that transmits data to a plurality of terminals according to a predetermined wireless communication standard, and continuously broadcasts and transmits a plurality of data blocks, and after the transmission of the plurality of data blocks is completed, it is determined that there is a data block that has failed to be received by receiving at least a part of the plurality of data blocks Broadcasting first notification data, which is a notification for causing a first terminal to make a declaration, and, as a response to the first notification data, when receiving second notification data indicating a data block that has failed to be received from one or more of the first terminals, retransmitting the data block indicated by the second notification data. It has a control unit that executes the above operations.

[0015] A wireless communication device is a device that continuously broadcasts a plurality of data blocks to a plurality of terminals according to a predetermined wireless communication standard. The predetermined wireless communication standard can be, for example, IEEE802.11 (IEEE802.11aa). Also, the first notification data is data for causing a terminal that has received at least a part of a plurality of data blocks to declare that there is a data block that has failed to be received. When a terminal that has received the first notification data has a data block that has failed to be received among a series of data blocks, it declares that fact by the second notification data. Also, when the control unit receives the second notification data, it retransmits the target data block. According to such a configuration, since only the terminals that have failed to receive the data (where a miss has occurred), rather than all terminals, return a negative response (second notification data), the overhead associated with communication can be reduced.

[0016] Note that the second notification data may include the sequence number of the data block that has failed to be received among the plurality of data blocks. In this case, the wireless communication device can retransmit only the data blocks that have failed to be received.

[0017] Also, before starting the broadcast transmission of a plurality of data blocks, the control unit may broadcast a signal announcing the start of transmission. In CSMA / CA, communication is initiated using backoff, so there is no mechanism for a specific communication device to preferentially transmit multiple data blocks together. Therefore, before transmitting multiple data blocks, a signal is broadcast to indicate the start of transmission, and terminals that receive this signal may temporarily suspend data transmission. The signal in question may, for example, request that data transmission be stopped until the first notification data is sent (in other words, until the transmission of a series of data blocks is complete). This configuration makes it possible to prioritize continuous data transmission in the wireless communication device.

[0018] The following describes specific embodiments of this disclosure with reference to the drawings. Unless otherwise specified, the hardware configurations, module configurations, functional configurations, etc., described in each embodiment are not intended to limit the technical scope of the disclosure to those configurations alone.

[0019] (First embodiment) An overview of the communication system according to the first embodiment will be described with reference to Figure 1. In this embodiment, the communication system is a system in which a server device 400 generates data to be distributed to multiple vehicles 10 and broadcasts this data to the multiple vehicles 10 via a predetermined wireless network. The predetermined wireless network is, for example, a network to which vehicles 10 in motion can connect via access points 200 installed on the roadside. The system may include multiple vehicles 10 (onboard devices 100).

[0020] Vehicle 10 is a connected car with wireless communication capabilities. Vehicle 10 can connect to one or more wireless networks via access points 200 installed on the roadside and receive data distributed from server devices 400. The illustrated communication system includes: It may include multiple wireless networks.

[0021] The server device 400 is a device that provides information to the vehicle 10 (in-vehicle device 100). The server device 400 determines the wireless network to which the data will be distributed and broadcasts the data via the access point 200 of that wireless network. As a result, the data is transmitted to all vehicles 10 (in-vehicle devices 100) connected to the target wireless network. The wireless network to which vehicle 10 is connected and the local network where the server device 400 is located are connected to each other via a WAN such as the Internet.

[0022] The wireless network includes an access point 200 that communicates wirelessly with the in-vehicle device 100, and a gateway 300 that serves as a gateway to the internet. The access point 200 is a device that provides wireless access to the wireless network.

[0023] The wireless network and the server device 400 are interconnected by a WAN (typically the Internet, etc.). The wireless network may be a network using Wi-Fi (registered trademark), or a mobile communication network using a cellular communication method. When using a mobile communication network, the access point 200 becomes a base station.

[0024] Each element that makes up the system will be explained in detail. Vehicle 10 is a connected car that has the ability to communicate with an external network. Vehicle 10 is equipped with an in-vehicle device 100.

[0025] The in-vehicle device 100 is a computer for collecting information. In this embodiment, the in-vehicle device 100 has the function of providing information to the occupants of the vehicle 10 based on data received from the server device 400. The in-vehicle device 100 may be a device that provides information to the occupants of the vehicle 10 (for example, a car navigation system), or it may be an electronic control unit (ECU) of the vehicle 10. Alternatively, the in-vehicle device 100 may be a data communication module (DCM) with communication capabilities.

[0026] The in-vehicle device 100 can be configured as a computer having a processor such as a CPU or GPU, main memory such as RAM or ROM, and auxiliary storage such as an EPROM, hard disk drive, or removable media. The auxiliary storage contains an operating system (OS), various programs, various tables, etc., and by executing the programs stored therein, various functions that match a predetermined purpose, as described later, can be realized. However, some or all of the functions may be realized by hardware circuits such as ASICs or FPGAs.

[0027] Figure 2 shows the system configuration of the in-vehicle device 100. The in-vehicle device 100 is configured to include a control unit 101, a storage unit 102, a communication unit 103, and an input / output unit 104.

[0028] The control unit 101 is a computing unit that realizes various functions of the in-vehicle device 100 by executing a predetermined program. The control unit 101 may be implemented by, for example, a CPU. The control unit 101 is configured as a functional module, having a function providing unit 1011. This functional module may be implemented by the CPU executing a stored program.

[0029] The function-providing unit 1011 performs various functions provided by the in-vehicle device 100. Examples of functions provided by the in-vehicle device 100 include the following: • Navigation function This function provides route navigation based on map data provided by the server device 400. ·Traffic information acquisition function This function provides traffic information and controls the vehicle 10 based on information provided by the server device 400. The traffic information may be information necessary for autonomous or semi-autonomous driving. For example, based on data broadcast at an intersection, vehicle control can be performed when passing through that intersection. These functions can be provided, for example, via the input / output unit 104 (touch panel). Alternatively, these functions may be provided via the electronic control unit of the vehicle 10. Furthermore, in order to provide these functions, the in-vehicle device 100 may have a GPS antenna, a GPS module, or the like.

[0030] The function provisioning unit 1011 is configured to be able to execute these functions using data transmitted from the server device 400.

[0031] The storage unit 102 is a memory device that includes a main memory and an auxiliary storage device. The auxiliary storage device stores the operating system (OS), various programs, various tables, etc., and by loading the programs stored therein into the main memory and executing them, various functions that match a predetermined purpose, as described later, can be realized. Main memory may include RAM (Random Access Memory) and ROM (Read Only Memory). Auxiliary storage may include EPROM (Erasable Programmable ROM) and hardware. This may include disk drives (HDD, Hard Disk Drive). Furthermore, auxiliary storage devices may also be included. This may include removable media, i.e., portable recording media.

[0032] The communication unit 103 is a wireless communication interface for connecting the in-vehicle device 100 to a wireless network. The communication unit 103 is configured to communicate with a wireless network using, for example, a communication standard such as mobile communication, wireless LAN, Bluetooth®, or DSRC.

[0033] The input / output unit 104 is a means for receiving input operations performed by the user of the device and presenting information. In this embodiment, it consists of a single touch panel display. That is, it is composed of a liquid crystal display and its control means, and a touch panel and its control means.

[0034] When the vehicle 10 (onboard device 100) detects the access point 200 by receiving a beacon signal, it establishes a connection with the access point 200 and connects to a predetermined wireless network via the access point 200. The wireless network is configured to include a gateway 300 to a wide-area network (Internet), and the onboard device 100 becomes able to communicate with the server device 400 via the gateway 300.

[0035] Next, the server device 400 will be described. The server device 400 is a device that provides information to multiple in-vehicle devices 100.

[0036] The server device 400 includes a processor such as a CPU or GPU, main memory such as RAM or ROM, and auxiliary storage such as an EPROM, hard disk drive, and removable media. It can be configured as a computer. The server device 400 may consist of a single computer or multiple computers that cooperate with each other.

[0037] The server device 400 first determines the wireless network to which it will broadcast the data. The wireless network to which it will broadcast the data can be determined, for example, based on its geographical location. Secondly, the server device 400 generates data to be broadcast to the in-vehicle device 100 connected to the target wireless network. In this embodiment, the data broadcast to the in-vehicle device 100 is a set of data consisting of multiple data blocks.

[0038] Figure 3 shows an example of an IP packet generated by the server device 400. In this embodiment, the server device 400 continuously broadcasts multiple such IP packets to the in-vehicle device 100 connected to the target wireless network via the access point 200. The transmitted IP packets include a sequence number indicating the order in which the data is transmitted. Such IP packets are sent to access point 200 via gateway 300.

[0039] Next, the access point 200 will be described. The access point 200 is a device that broadcasts data generated by the server device 400 to multiple in-vehicle devices 100. The access point 200 also controls data retransmission based on the results of its interaction with the in-vehicle devices 100.

[0040] Figure 4 shows the system configuration of the access point 200. The access point 200 consists of a control unit 201, a storage unit 202, and a communication unit 203.

[0041] The control unit 201 is a computing device that manages the control performed by the access point 200. The control unit 201 can be implemented by a computing device such as a CPU. The control unit 201 is configured to have two functional modules: an information transmission unit 2011 and an information retransmission unit 2012. Each functional module may be implemented by the CPU executing a program stored in an auxiliary storage means.

[0042] The information transmission unit 2011 acquires data from the server device 400 to be broadcast to multiple in-vehicle devices 100 connected to a predetermined wireless network, and controls the transmission of said data. For example, if there is a wireless network that a vehicle 10 located near a certain intersection can connect to, the safety of vehicles passing through the intersection can be improved by broadcasting data regarding the traffic conditions at that intersection to the vehicle 10 connected to that wireless network.

[0043] In this embodiment, IP packets generated by the server device 400 are broadcast to all in-vehicle devices 100 connected to the target wireless network. The destination address set in the IP packet header is a broadcast address that targets all devices included in the target wireless network.

[0044] The information retransmission unit 2012 determines if any of the data blocks broadcast to multiple in-vehicle devices 100 failed to be received by any of the in-vehicle devices 100, and retransmits the data block in question. The specific method will be described later.

[0045] The storage unit 202 comprises a main memory and an auxiliary storage device. The main memory is the memory where programs executed by the control unit 201 and data used by said control programs are stored. The auxiliary storage device is the device where programs executed by the control unit 201 and data used by said control programs are stored.

[0046] The communication unit 203 is a communication interface for connecting the access point 200 to a network. The communication unit 203 is configured to include a wireless communication interface for wireless connection with the in-vehicle device 100 and a wired communication interface for connection to a WAN.

[0047] Note that the configurations shown in Figures 2 and 4 are examples, and all or part of the illustrated functions may be performed using specially designed circuits. Furthermore, program storage and execution may be performed using combinations of main memory and auxiliary memory other than those shown.

[0048] Next, we will explain in more detail how the access point 200, which has acquired data from the server device 400, broadcasts that data to the in-vehicle device 100.

[0049] Figure 5 is a sequence diagram of the process by which the access point 200 broadcasts data to the in-vehicle device 100. In this example, three in-vehicle devices 100A, 100B, and 100C are shown as examples of multiple in-vehicle devices 100.

[0050] First, the access point 200 (information transmission unit 2011) transmits a signal (BusyTone signal, hereinafter referred to as BT signal) to multiple in-vehicle devices 100 to request a temporary suspension of data transmission. In wireless communication standards using the CSMA / CA method, when multiple terminals transmit data, they wait for a random backoff time before listening on the channel. In other words, there is no mechanism for preferentially transmitting data from one device to another. Therefore, in this embodiment, the access point 200 transmits a BT signal to the target wireless network, and the in-vehicle device 100 that receives this signal temporarily stops data transmission. It is preferable to send the BT signal for an extremely short time to avoid collisions with other communications.

[0051] When the in-vehicle device 100 receives a BT signal, it switches to a mode (hereinafter referred to as "receiving mode") in which it stops transmitting data until it receives a BRP, which will be described later.

[0052] When access point 200 transmits a BT signal, it begins broadcasting data. Data transmission is performed by sending multiple data blocks sequentially. Each of these data blocks is assigned a sequence number, as shown in Figure 3. The sequence number indicates the total number of data blocks to be transmitted and the position of the current data within that total.

[0053] The in-vehicle device 100 records a sequence number each time it receives data. This allows the in-vehicle device 100 to determine which data block is missing, even if a data block fails to be received. In the illustrated example, assume that the in-vehicle device 100C failed to receive the first data block.

[0054] Once the transmission of a series of data blocks is complete, the access point 200 sends a notification (Broadcast Return) to the in-vehicle device 100 to inform it that there are data blocks that have failed to be received. An assignment Polling (hereinafter referred to as BRP) is generated and broadcast.

[0055] Upon receiving the BRP, the in-vehicle device 100 refers to the recorded sequence number and determines whether there are any data blocks that failed to be received. In this example, the in-vehicle device 100C determines that it failed to receive the first data block. If the in-vehicle device 100 fails to receive a data block, it will respond to the BRP by sending a notification to the access point 200 indicating that there is a data block that failed to be received (Broadcast Retransmission Polling Ack, hereinafter referred to as BRPA). The BRPA contains the sequence number of the data block that failed to be received.

[0056] When access point 200 receives a BRPA, it retransmits the data block with the declared sequence number. For example, if a dataset consisting of multiple data blocks is to be transmitted multiple times, the data block with the declared sequence number may be retransmitted at subsequent transmission times. In this example, the first data block is broadcast again prior to subsequent data transmissions.

[0057] Next, a flowchart of the processes performed by the in-vehicle device 100 and the access point 200 will be described. Figure 6 is a flowchart of the processes performed by the in-vehicle device 100. The illustrated processes are repeatedly executed when the device is in a receiving standby state.

[0058] First, in step S11, it is determined whether or not a BT signal has been received from the access point 200. If a BT signal is received, the process proceeds to step S12. If a BT signal is not received, the process ends. In step S12, the device switches to receive mode. When switching to receive mode, data transmission from the device is temporarily stopped.

[0059] In step S13, the broadcast-transmitted data block is received, and it is determined whether all the data blocks received so far are consecutive. If there are any consecutively received data blocks with missing sequence numbers, it is determined that the reception of that data block failed. If there are any data blocks that were not received, the process proceeds to step S14, where the sequence number of that data block is stored.

[0060] In step S15, it is determined whether or not a BRP has been received from access point 200. If a BRP has not been received, the process returns to step S13 and continues receiving data blocks. If a BRP has been received, the process transitions to step S16 and the receive mode is canceled.

[0061] In step S17, it is determined whether the sequence number of the data block that failed to be received is stored. If there is a data block that failed to be received, the process proceeds to step S18, where a BRPA containing the sequence number of the data block is generated and sent to the access point 200.

[0062] Figure 7 is a flowchart showing the details of the process in step S18. First, in step S181, a random backoff time is determined. Next, in step S182, the system waits for a certain period of time (DIFS). DIFS is the time it takes for a busy channel to stop receiving signals and for the system to be determined to have transitioned to an idle state. In step S183, it is determined whether the channel is idle or not. If the channel is idle, the process proceeds to step S184, where a BRPA is sent to the access point 200 by unicast. If the channel is not idle, the process returns to step S182. Through the above process, BRPA is transmitted from the in-vehicle device 100 to the access point 200.

[0063] Next, we will explain the flowchart of the processes performed by access point 200. Figure 8 is a flowchart of the processes performed by access point 200.

[0064] First, in step S21, it is determined whether the preparation of data to be broadcasted to multiple in-vehicle devices 100 is complete. If the preparation of data to be broadcasted is complete and transmission is to begin, the process proceeds to step S22. In step S22, the information transmission unit 2011 generates a BT signal and broadcasts it to the in-vehicle device 100 within the target wireless network.

[0065] Figure 9 is a flowchart showing the details of the process in step S22. First, in step S221, a random backoff time is determined. Next, in step S222, the system waits for a certain period of time (DIFS). In step S223, it is determined whether the channel is idle or not. If the channel is idle, the process proceeds to step S224, and the BT signal is broadcast to multiple in-vehicle devices 100. If the channel is not idle, the process returns to step S222. Through the above process, a BT signal is transmitted from the access point 200 to the in-vehicle device 1000.

[0066] Next, in step S23, it is determined whether or not a BRPA was received during the previous data transmission. If a BRPA was received during the previous data transmission, it means that the data needs to be retransmitted. In this case, the process proceeds to step S24, and the data block to be retransmitted (i.e., the data block with the sequence number indicated by the BRPA) is broadcast.

[0067] In step S25, multiple data blocks to be transmitted are broadcast sequentially. After a data block is transmitted, in step S26, it is determined whether there are subsequent data blocks. If there are subsequent data blocks, the process returns to step S25 and broadcast transmission continues.

[0068] Once the transmission of multiple data blocks is complete, step S27 broadcasts a BRP and listens for a BRPA sent from the in-vehicle device 100. If a BRPA is received, step S24 is executed in the next cycle, and the target data block is retransmitted. If no BRPA is sent from any of the in-vehicle devices 100, the process ends with a timeout.

[0069] As described above, in the communication system according to the first embodiment, the access point 200 broadcasts multiple data blocks to multiple in-vehicle devices 100, and then sends a notification (BRP) to cause a negative response to be sent. With this configuration, only the in-vehicle device that fails to receive the data sends a negative response (retransmission request), thus reducing communication overhead.

[0070] (modified version) The embodiments described above are merely examples, and this disclosure may be modified as appropriate without departing from its essence. For example, the processes and means described in this disclosure can be freely combined and implemented, as long as no technical inconsistencies arise.

[0071] Furthermore, a process described as being performed by a single device may be divided and executed by multiple devices. Conversely, a process described as being performed by different devices may be executed by a single device. In a computer system, the hardware configuration (server configuration) by which each function is implemented can be flexibly changed.

[0072] The present disclosure can also be realized by supplying a computer program implementing the functions described in the embodiments above to a computer, and having one or more processors in the computer read and execute the program. Such a computer program may be provided to the computer by a non-temporary computer-readable storage medium that can be connected to the computer's system bus, or it may be provided to the computer via a network. Non-temporary computer-readable storage mediums include, for example, any type of disk such as magnetic disks (floppy disks, hard disk drives (HDDs), etc.), optical disks (CD-ROMs, DVDs, Blu-ray discs, etc.), read-only memory (ROM), random access memory (RAM), EPROM, EEPROM, magnetic cards, flash memory, optical cards, and any type of medium suitable for storing electronic instructions. [Explanation of symbols]

[0073] 10.. Vehicles 100...In-vehicle equipment 200 access points 101,201...Control Unit 102,202...Storage section 103,203... Communications Department 104...Input / output section 300 Gateway 400... Server equipment

Claims

1. A wireless communication system including a first wireless communication device and a second wireless communication device, The first wireless communication device, The second wireless communication device receives multiple data blocks broadcasted according to a predetermined wireless communication standard, The second wireless communication device receives a first notification data, which is a notification to report that there are data blocks that failed to be received, which is broadcast transmitted after the transmission of the plurality of data blocks has been completed. If the sequence numbers of the received data blocks are not consecutive, a second notification data indicating only the missing sequence numbers among the data blocks is transmitted to the second wireless communication device in response to the first notification data. Execute, The second wireless communication device is The above-mentioned multiple data blocks are broadcast in succession, After the transmission of the aforementioned multiple data blocks is completed, the first notification data is broadcast. In response to the first notification data, if the second notification data is transmitted from the first wireless communication device, the data block having the sequence number indicated by the second notification data is to be retransmitted. Execute Wireless communication system.

2. The first wireless communication device is If the sequence numbers of the aforementioned multiple data blocks are not consecutive, the sequence number of the missing data block is recorded. The wireless communication system according to claim 1.

3. The second wireless communication device, in order to perform the retransmission, broadcasts again only the data block containing the sequence number included in the second notification data from among the plurality of data blocks. The wireless communication system according to claim 2.

4. The second wireless communication device broadcasts a signal to announce the start of transmission of the plurality of data blocks before starting broadcast transmission of the plurality of data blocks. A wireless communication system according to any one of claims 1 to 3.

5. The first wireless communication device, upon receiving the signal, temporarily suspends data transmission. The wireless communication system according to claim 4.

6. The first wireless communication device, upon receiving the signal, temporarily suspends data transmission until it receives the first notification data. The wireless communication system according to claim 4.

7. The aforementioned specified wireless communication standard is IEEE 802.11aa. The wireless communication system according to claim 1.

8. A wireless communication method performed by a first wireless communication device and a second wireless communication device, The first wireless communication device, The second wireless communication device receives multiple data blocks broadcasted according to a predetermined wireless communication standard, The second wireless communication device receives a first notification data, which is a notification to report that there are data blocks that failed to be received, which is broadcast transmitted after the transmission of the plurality of data blocks has been completed. If the sequence numbers of the received data blocks are not consecutive, a second notification data indicating only the missing sequence numbers among the data blocks is transmitted to the second wireless communication device in response to the first notification data. Execute, The second wireless communication device is The above-mentioned multiple data blocks are broadcast in succession, After the transmission of the aforementioned multiple data blocks is completed, the first notification data is broadcast. In response to the first notification data, if the second notification data is transmitted from the first wireless communication device, the data block having the sequence number indicated by the second notification data is to be retransmitted. Execute Wireless communication method.

9. The first wireless communication device, If reception of any of the aforementioned data blocks fails, the step of recording the sequence number of the corresponding data block is further performed. The second notification data, including the sequence number, is transmitted. The wireless communication method according to claim 8.

10. The second wireless communication device further performs the step of broadcasting again only the data block containing the sequence number included in the second notification data from among the plurality of data blocks in order to perform the retransmission. The wireless communication method according to claim 9.

11. The second wireless communication device further performs the step of broadcasting a signal that foreshadows the start of transmission of the plurality of data blocks before starting broadcast transmission of the plurality of data blocks. The wireless communication method according to any one of claims 8 to 10.

12. The first wireless communication device, upon receiving the signal, temporarily suspends data transmission. The wireless communication method according to claim 11.

13. The first wireless communication device, upon receiving the signal, temporarily suspends data transmission until it receives the first notification data. The wireless communication method according to claim 11.

Images