Communication method and communication system

Abstract

An exemplary communication method is a communication method using a preamble between a first communication device and a second communication device. The first communication device communicates with the second communication device using a preamble type determined according to the use of communication among a plurality of preamble types determined by the pulse repetition frequency of the preamble or the length of the preamble.

Description

TECHNICAL FIELD

[0001] The present application relates to a communication technology using a preamble. BACKGROUND

[0002] In recent years, in the field of communication, wireless communication is gradually increasing due to advantages such as no need for wiring and the like. For example, UWB (Ultra Wide Band) communication using a wideband wave has less wave interference with a wave used in a portable terminal such as a Wi-Fi (registered trademark) and a smartphone, and is excellent in permeability, and its use is expanding. In addition, UWB communication is easy to establish communication in a narrow space of metal and in a vehicle interior where wiring is abundant, and is expected as a communication means for a vehicle-mounted device.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENT

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-38332 SUMMARY

[0006] -PROBLEMS TO BE SOLVED BY THE INVENTION-

[0007] However, in a case where UWB communication is widely spread, even UWB is likely to cause interference of UWB communication with each other, and there is a concern that communication interruption occurs due to the interference. This problem of communication interruption is not limited to a communication means for a vehicle-mounted device and UWB communication, and is also likely to occur in a case where a plurality of devices communicate using the same frequency band wave.

[0008] In view of such a problem, in Patent Document 1, a technology of reducing a communication rate to prevent interference is disclosed. However, it is desired to be able to prevent interference without reducing the communication rate. In addition, in a case where there are a plurality of communication use purposes, it is preferable that a communication success rate of communication of a use purpose with high priority (importance) is higher than a communication success rate of communication of a use purpose with low priority (importance).

[0009] In view of the above problem, an object of the present application is to provide a technology capable of improving a communication success rate in communication of a use purpose with high priority.

[0010] - MEANS FOR SOLVING THE PROBLEMS -

[0011] An exemplary communication method of the present application is a communication method using a preamble between a first communication device and a second communication device, the first communication device communicating with the second communication device using a kind of preamble decided in accordance with a use purpose of communication from among a plurality of kinds of preambles decided by a pulse repetition frequency of a preamble or a length of a preamble.

[0012] - Invention Effects -

[0013] According to the present application, the preamble for communication can be appropriately set according to the use of the communication, and thus the communication success rate in the communication of the use with high priority can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a diagram showing a structure example of a communication system.

[0015] Figure 2 is a diagram showing a frame format used for UWB communication.

[0016] Figure 3A is a diagram showing a first decision mode included in the first decision example of the kind of preamble.

[0017] Figure 3B is a diagram showing a second decision mode included in the first decision example of the kind of preamble.

[0018] Figure 3C is a diagram showing a third decision mode included in the first decision example of the kind of preamble.

[0019] Figure 4A is a diagram showing a fourth decision mode included in the second decision example of the kind of preamble.

[0020] Figure 4B is a diagram showing a fifth decision mode included in the second decision example of the kind of preamble.

[0021] Figure 4C is a diagram showing a sixth decision mode included in the second decision example of the kind of preamble.

[0022] Figure 4D is a diagram showing a modification example of the fourth decision mode.

[0023] Figure 4E is a diagram showing a modification example of the fourth decision mode.

[0024] Figure 5 is a diagram showing a seventh decision mode included in the third decision example of the kind of preamble.

[0025] Figure 6 is a diagram for explaining a problem point at the time of reception in UWB communication.

[0026] Figure 7 is a diagram showing an outline of an electric wave interference countermeasure in a communication system.

[0027] Figure 8 is a diagram showing a structure example of a main communication device.

[0028] Figure 9 This is a flowchart illustrating an example of the operation of the main communication device.

[0029] Figure 10 This is a diagram illustrating a data format example for a wireless communication plan.

[0030] Figure 11 This is a diagram illustrating an example of the structure of a communication device.

[0031] Figure 12 This is a flowchart illustrating an example of the operation of a communication device.

[0032] Figure 13 It is used to describe the start time τ of the receive mode. start A detailed example of the setting method is shown in the diagram.

[0033] Figure 14 This is a schematic diagram illustrating an example of the operation of a communication system according to a wireless communication plan.

[0034] Figure 15 This is a diagram illustrating the structural example of the communication system involved in the first variation.

[0035] Figure 16 This is a diagram showing the relationship between the master communication device and the slave communication device in the communication system involved in the first modification.

[0036] Figure 17 This is a diagram showing the structure of the communication system involved in the second variation.

[0037] Figure 18 This is a flowchart illustrating an example of the processing performed by the main communication device during the calibration of radio wave output.

[0038] Figure 19 It is used to explain the execution Figure 18 The diagram shows the operation of the master and slave communication devices during processing.

[0039] Figure 20 This is an example of a correlation diagram showing the relationship between the distance between devices and the transmission power. Detailed Implementation

[0040] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in the description of the embodiments, the same reference numerals are used to denote the same parts, and repeated descriptions are omitted unless specifically required.

[0041] <1. Communication System>

[0042] Figure 1This diagram illustrates a structural example of the communication system SYS1 according to an embodiment of the present invention. In this embodiment, as an example, the communication system SYS1 is mounted on a vehicle C1. However, the communication system SYS1 can also be applied to vehicles other than C1, for example, not limited to automobiles, and can also be used as a mobile unit, for home use, office use, or factory use.

[0043] like Figure 1 As shown, the communication system SYS1 includes a main ECU (Electric Control Unit) 10 and multiple slave devices 20a to 20d. The communication system SYS1 is, for example, a vehicle control system in which the main ECU 10 controls each slave device 20a to 20d via UWB communication based on user operations on the HMI (Human Machine Interface) 30. Specifically, each slave device 20a to 20d sends sensor values ​​detected by sensors connected to it to the main ECU 10. Each slave device 20a to 20d controls its connected actuators based on control signals sent from the main ECU 10.

[0044] The first slave device 20a is, for example, a control device that controls the drive of the headlights. The second slave device 20b is, for example, a control device that controls the drive of the windshield wipers. The third slave device 20c is, for example, a control device that controls the drive of the power windows. The fourth slave device 20d is, for example, a control device that controls the drive of the air conditioner.

[0045] Since UWB communication is performed between the main ECU 10 and each of the slave devices 20a to 20d, the main ECU 10 will be referred to as the main communication device 10, and the slave devices 20a to 20d will be referred to as slave communication devices 20a to 20d. Furthermore, when it is not necessary to explain the multiple slave communication devices 20a to 20d separately, the slave communication devices 20a to 20d may sometimes be simply referred to as slave communication devices 20.

[0046] Furthermore, in this embodiment, there are multiple communication devices 20, but there can also be a single one. In addition, the multiple communication devices in the communication system do not necessarily need to be in a master-slave relationship; they can also be in a peer-to-peer relationship.

[0047] Furthermore, in this embodiment, the master communication device 10 and the slave communication device 20 perform UWB communication as described above. That is, the wireless communication in this embodiment is wireless communication based on the UWB communication method. UWB communication is performed, for example, according to a standard such as IEEE 802.15.4 (hereinafter sometimes simply referred to as the communication standard). However, wireless communication can also be communication using a preamble other than UWB communication, such as Wi-Fi communication, Bluetooth communication, BLE communication, LPWA (Low Power Wide Area) communication, Zigbee communication, etc.

[0048] The master communication device 10 can transmit signals to the slave communication device 20 and receive signals from the slave communication device 20. Similarly, the slave communication device 20 can receive signals from the master communication device 10 and transmit signals to the master communication device 10. In other words, the communication system SYS1 includes a transmitting device for transmitting wirelessly and a receiving device for receiving wirelessly. The master communication device 10 and the slave communication device 20 can each be either the transmitting device or the receiving device. In other words, the master communication device 10 acts as a transmitting device in signal transmission mode and a receiving device in signal reception mode. Similarly, the slave communication device 20 also acts as a transmitting device in signal transmission mode and a receiving device in signal reception mode.

[0049] In this embodiment, the main communication device 10 communicates with each of the slave communication devices 20a to 20d via UWB. Therefore, the communication system SYS1 helps to reduce the wiring harness used in the vehicle C1.

[0050] The main communication device 10 and the slave communication device 20 are communication devices used for data communication.

[0051] The communication system SYS1 also includes a ranging communication device 40 and a radar communication device 50.

[0052] In this embodiment, the ranging communication device 40 and the radar communication device 50 respectively perform UWB communication. That is, the wireless communication of the ranging communication device 40 and the radar communication device 50 is based on UWB communication. However, the wireless communication of the ranging communication device 40 and the radar communication device 50 can also be communication using a preamble other than UWB communication, such as Wi-Fi communication, Bluetooth communication, BLE communication, LPWA communication, Zigbee communication, etc.

[0053] The ranging communication device 40 is a communication device used for ranging communication. The ranging communication device 40 communicates wirelessly with the electronic key 60. The ranging communication device 40 sends a signal to the electronic key 60. After receiving the signal from the ranging communication device 40, the electronic key 60 sends a reply signal back to the ranging communication device 40. The ranging communication device 40 receives the reply signal from the electronic key 60, determines the time required from the transmission of the signal to the reception of the reply signal, and calculates the distance to the electronic key 60 based on the determined time.

[0054] The radar communication device 50 is a communication device used for radar communication. The radar communication device 50 emits (transmits) signals and detects (receives) signals reflected back from objects. The radar communication device 50 measures the time required from the emission of the signal to the reception of the reflected signal, and calculates the distance to the (reflecting) object based on the measured time. When the radar communication device 50 emits (transmits) signals into the interior of the vehicle C1, it can be used as a device to monitor the presence and actions of occupants. Conversely, when the radar communication device 50 emits (transmits) signals outside the vehicle C1, it can be used as a device to monitor the presence and actions of obstacles located around the vehicle C1.

[0055] <2. Determining the Type of Preamble>

[0056] [2-1. Frame Format]

[0057] Here, use Figure 2 This section describes the format (hereinafter referred to as frame format) of a communication frame (a unit of transmitted data) in UWB communication. The frame format used in UWB communication is determined by the aforementioned communication standard.

[0058] like Figure 2 As shown, the frame format F used for UWB communication has a structure consisting of an SFD (Start Frame Delimiter), a PHR (PHY Header), and a data body, connected sequentially starting with a preamble. Additionally, the data body contains statements used to facilitate understanding of the differences between the data body and the preamble, SFD, and PHR.

[0059] A preamble is a string of bits of a given pattern, or a sequence of pulses (e.g., -, 0, +), sent before the data body at the receiving end in digital communication to indicate "data is to be sent from here." The receiving end uses the preamble signal to start (synchronize) its receiving clock. There are multiple patterns of preambles; in other words, there are several types of preambles.

[0060] As configurable physical layer parameters for the preamble, there are the preamble signal code and the preamble length (preamble length).

[0061] The preamble signal codes are of 24 types, numbered 1 to 24. Signal codes 1 to 8 have a PRF (Pulse Repletion Frequency) of 16 MHz. Signal codes 9 to 24 have a PRF of 64 MHz.

[0062] The preamble length is determined by the number of symbols contained in the preamble. The preamble length can be selected from patterns such as 16 symbols, 64 symbols, 128 symbols, 256 symbols, 512 symbols, 1024 symbols, 2048 symbols, and 4096 symbols.

[0063] A preamble is a sequence of bits or pulses (e.g., -, 0, +) that use a predetermined pattern such as "10101010...". The preamble length is the size (length) of the preamble, which is longer the number of symbols it contains.

[0064] SFD is a specific pattern of bit strings used to indicate the start of data in a communication frame. PHR includes information needed to interpret the data packet. For example, PHR includes the address of the communication object, the data length of the subsequent data, etc. Data body is the body of the information to be sent to the communication object, including the actual data to be transmitted. For example, data body includes the ID information of the receiving destination of the communication frame, the ID information of the sending source, the instruction information of the master communication device 10 to the slave communication device 20, the sensor values ​​detected by the sensors of the slave communication device 20, the operating status of the actuator that is controlled by the slave communication device 20, etc.

[0065] In this embodiment, the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each use a type of preamble determined from multiple types of preambles, which are determined by the pulse repetition frequency or length of the preamble, according to the intended use of the communication. Since different types of preambles have varying degrees of resistance to radio interference, using a type of preamble with superior resistance to radio interference, which is used in high-priority applications, can improve the communication success rate in high-priority applications. Therefore, the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble based on the priority of the intended use and use the determined type of preamble.

[0066] [2-2. First Decision Example]

[0067] For example, the main communication device 10, the slave communication device 20, the ranging communication device 40, and the radar communication device 50 each use a type of preamble selected from a plurality of types determined by the pulse repetition frequency of the preamble, based on the intended use of the communication. Since the pulse repetition frequency of the preamble varies in its resistance to radio interference, setting the pulse repetition frequency of the preamble used in high-priority communications to a frequency with excellent resistance to radio interference can improve the communication success rate in high-priority communications.

[0068] More specifically, a higher pulse repetition frequency of the preamble results in better resistance to radio interference. Therefore, by setting a high pulse repetition frequency of the preamble used in high-priority communications, the communication success rate in high-priority applications can be improved. This relationship between the pulse repetition frequency of the preamble and its resistance to radio interference is considered the reason why the receiver of a communication device preferentially resolves preambles with high pulse repetition frequencies.

[0069] Therefore, when the first use is prioritized over the second use, the pulse repetition frequency determined when the communication use is the first use can be set to a higher frequency than when the communication use is the second use. Similarly, when the first use is prioritized over the third use, the pulse repetition frequency determined when the communication use is the first use can be set to a higher frequency than when the communication use is the third use.

[0070] In the first decision example, the preamble length can be set to a single length regardless of the intended use of the communication.

[0071] Figure 3A This is a diagram illustrating the first decision mode included in the first decision example. The first decision mode is the decision mode in cases where the first use is for data communication, the second use is for ranging communication and radar communication, and the third use is for ranging communication and radar communication.

[0072] When the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the first determination mode, the preamble signal code used in the communication between the master communication device 10 and the slave communication device 20 becomes any one of signal code 9 to signal code 24. Therefore, the pulse repetition frequency of the preamble used in the communication between the master communication device 10 and the slave communication device 20 becomes 64MHz. Furthermore, when the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the first determination mode, the preamble signal code used in the communication between the ranging communication device 40 and the radar communication device 50 becomes any one of signal code 1 to signal code 8. Therefore, the pulse repetition frequency of the preamble used in the communication between the ranging communication device 40 and the radar communication device 50 becomes 16MHz.

[0073] Figure 3B This diagram illustrates the second decision mode included in the first decision example. The second decision mode is the decision mode in cases where the first use is for ranging communication, the second use is for data communication and radar communication, and the third use is for data communication and radar communication.

[0074] When the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the second determination mode, the preamble signal code used in the communication conducted by the ranging communication device 40 becomes any one of signal code 9 to signal code 24. Therefore, the pulse repetition frequency of the preamble used in the communication conducted by the ranging communication device 40 becomes 64MHz. Furthermore, when the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the second determination mode, the preamble signal code used in the communication conducted by each of the master communication device 10, slave communication device 20, and radar communication device 50 becomes any one of signal code 1 to signal code 8. Therefore, the pulse repetition frequency of the preamble used in the communication conducted by each of the master communication device 10, slave communication device 20, and radar communication device 50 becomes 16MHz.

[0075] Figure 3C This diagram illustrates the third decision mode included in the first decision example. The third decision mode is the decision mode in cases where the first use is radar communication, the second use is data communication and ranging communication, and the third use is data communication and ranging communication.

[0076] When the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the third determination mode, since the preamble signal code of the preamble used in the communication conducted by the radar communication device 50 is any one of signal code 9 to signal code 24, the pulse repetition frequency of the preamble used in the communication conducted by the radar communication device 50 becomes 64MHz. Furthermore, when the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the third determination mode, since the preamble signal code of the preamble used in the communication conducted by the master communication device 10, slave communication device 20, and ranging communication device 40 becomes any one of signal code 1 to signal code 8, the pulse repetition frequency of the preamble used in the communication conducted by the master communication device 10, slave communication device 20, and ranging communication device 40 becomes 16MHz.

[0077] In the first example, the type of preamble is the same in both the second and third uses. In other words, in the first example, the type of preamble can be the same even if the uses of communication are different. This allows for a wider variety of preamble types to be used in the second and third uses, thus increasing the freedom in setting the type of preamble.

[0078] [2-3. Example of a second decision]

[0079] For example, the main communication device 10, the slave communication device 20, the ranging communication device 40, and the radar communication device 50 each use a type of preamble determined from multiple types of preambles whose length is determined by the preamble, based on the intended use of the communication. Since different preamble lengths have varying degrees of resistance to radio interference, by setting the length of the preamble used in high-priority communications to a length with superior resistance to radio interference, the communication success rate in high-priority communications can be improved.

[0080] More specifically, the longer the preamble, the better the resistance to radio interference. Therefore, by setting a longer preamble length in communications used for high-priority applications, the success rate of communications in high-priority applications can be improved.

[0081] Therefore, if the first purpose is a priority over the second purpose, the preamble length determined when the communication purpose is the first purpose can be set to be longer than the preamble length determined when the communication purpose is the second purpose. Similarly, if the first purpose is a priority over the third purpose, the preamble length determined when the communication purpose is the first purpose can be set to be longer than the preamble length determined when the communication purpose is the third purpose.

[0082] In the second example, the pulse repetition frequency of the preamble can be set to a single frequency regardless of the intended use of the communication.

[0083] Figure 4A This diagram illustrates the fourth decision mode included in the second decision example. The fourth decision mode is the decision mode in cases where the first use is for data communication, the second use is for one of ranging communication and radar communication, and the third use is for the other of ranging communication and radar communication.

[0084] When the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the fourth determination mode, the length of the preamble used in the communication between the master communication device 10 and the slave communication device 20 becomes 4096 symbols. Furthermore, when the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the fourth determination mode, the length of the preamble used in the communication between the ranging communication device 40 and the radar communication device 50 becomes any one of 16 symbols, 64 symbols, or 1024 symbols.

[0085] Figure 4B This diagram illustrates the fifth decision mode included in the second decision example. The fifth decision mode is the decision mode in cases where the first use is for ranging communication, the second use is for data communication and radar communication, and the third use is for data communication and radar communication.

[0086] When the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the fifth determination mode, the length of the preamble used in the communication conducted by the ranging communication device 40 becomes 4096 symbols. Furthermore, when the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the fifth determination mode, the length of the preamble used in the communication conducted by each of the master communication device 10, slave communication device 20, and radar communication device 50 is any one of 16 symbols, 64 symbols, or 1024 symbols.

[0087] Figure 4C This diagram illustrates the sixth decision mode included in the second decision example. The sixth decision mode is the decision mode in cases where the first use is for radar communication, the second use is for data communication and ranging communication, and the third use is for data communication and ranging communication.

[0088] When the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the sixth determination mode, the length of the preamble used in the communication conducted by the radar communication device 50 becomes 4096 symbols. Furthermore, when the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the sixth determination mode, the length of the preamble used in the communication conducted by each of the master communication device 10, slave communication device 20, and ranging communication device 40 is any one of 16 symbols, 64 symbols, or 1024 symbols.

[0089] In the fourth to sixth decision modes mentioned above, the preamble length corresponding to the preferred use is 4096 symbols, and the preamble length corresponding to other uses is any one of 16 symbols, 64 symbols, or 1024 symbols. However, these modes are not limited, and other modes may also be used as follows: Figure 4D As shown in the variant of the fourth decision mode, the preamble length corresponding to the preferred use is either 1024 symbols or 4096 symbols, and the preamble length corresponding to other uses is either 16 symbols or 64 symbols. Alternatively, it can be as follows... Figure 4E As with other variations of the fourth decision mode shown, the preamble length corresponding to the preferred use is any one of 64 symbols, 1024 symbols, or 4096 symbols, and the preamble length corresponding to other uses is 16 symbols.

[0090] In the second decision example, the type of preamble differs in the second intended use. Similarly, in the second decision example, the type of preamble differs in the third intended use. In other words, in the second decision example, even if the intended use of communication is the same, it is permissible to determine different types of preambles. Thus, even if the intended use of communication is the same, the type of preamble can be refined by other factors (such as the type of data, the type of object-side device for distance measurement, the type of obstacle (indoor obstacles, external obstacles), etc.), thereby increasing the freedom in setting the type of preamble.

[0091] [2-4. Example of a third decision]

[0092] For example, the main communication device 10, the slave communication device 20, the ranging communication device 40, and the radar communication device 50 each use a type of preamble determined from multiple types of preambles, which are determined by the pulse repetition frequency and the length of the preamble, according to the intended use of the communication. Since the pulse repetition frequency and the length of the preamble have varying degrees of resistance to radio interference, by setting the pulse repetition frequency of the preamble used in high-priority communication to a frequency with excellent resistance to radio interference, and by setting the length of the preamble used in high-priority communication to a length with excellent resistance to radio interference, the communication success rate in high-priority communication can be improved.

[0093] More specifically, the higher the pulse repetition frequency of the preamble, the better the resistance to radio interference. Therefore, the pulse repetition frequency of the preamble used in high-priority applications is set to be high. Furthermore, the longer the preamble, the better the resistance to radio interference. Therefore, the length of the preamble used in high-priority applications is set to be longer, thereby improving the communication success rate in high-priority applications.

[0094] Therefore, since the first use is prioritized over the second use, the pulse repetition frequency determined when the communication use is the first use can be set to be higher than the pulse repetition frequency determined when the communication use is the second use. Furthermore, the preamble length determined when the communication use is the first use can be set to be longer than the preamble length determined when the communication use is the second use. Similarly, since the first use is prioritized over the third use, the pulse repetition frequency determined when the communication use is the first use can be set to be higher than the pulse repetition frequency determined when the communication use is the third use. Furthermore, the preamble length determined when the communication use is the first use can be set to be longer than the preamble length determined when the communication use is the third use.

[0095] Figure 5 This diagram illustrates the seventh decision mode included in the third decision example. The seventh decision mode is the decision mode in cases where the first use is for data communication, the second use is for ranging communication and radar communication (one of the three uses), and the third use is for ranging communication and radar communication (the other of the three uses).

[0096] When the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the seventh determination mode, the preamble signal code used in the communication between the master communication device 10 and the slave communication device 20 becomes any one of signal code 9 to signal code 24. Therefore, the pulse repetition frequency of the preamble used in the communication between the master communication device 10 and the slave communication device 20 becomes 64MHz. Furthermore, when the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the seventh determination mode, the length of the preamble used in the communication between the master communication device 10 and the slave communication device 20 is any one of 64 symbols, 1024 symbols, or 4096 symbols. Furthermore, when the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the seventh determination mode, the preamble signal code used in the communication between the ranging communication device 40 and the radar communication device 50 becomes any one of signal code 1 to signal code 8. Therefore, the pulse repetition frequency of the preamble used in the communication between the ranging communication device 40 and the radar communication device 50 becomes 16 MHz. Moreover, when the master communication device 10, slave communication device 20, ranging communication device 40, and radar communication device 50 each determine the type of preamble according to the seventh determination mode, the length of the preamble used in the communication between the ranging communication device 40 and the radar communication device 50 becomes 16 symbols.

[0097] In the seventh decision mode, the preamble length is further refined according to the type of data in the first application. In data communication, when communicating the highest priority "safety data related to operation", the preamble length is set to 4096 symbols to improve resistance to radio wave interference. When communicating the second highest priority "body equipment data (such as windshield wiper devices)", the preamble length is set to 1096 symbols. When communicating the lowest priority "entertainment data (such as audio content and video content)", the preamble length is set to 64 symbols.

[0098] [2-5. Variations]

[0099] Unlike this embodiment, the ranging communication device 40 operates as a slave communication device 20 that performs data communication with the master communication device 10 upon startup. If the master communication device 10 instructs the user to switch the communication purpose from data communication to ranging communication via data communication, then the device can also be configured to switch the communication purpose from data communication to ranging communication. Such a ranging communication device 40, for example, includes a storage unit that stores a data table showing the correspondence between the communication purpose and the type of preamble used in the communication, and a current setting of at least one of the communication purpose and the type of preamble. The type of preamble used in the communication can be switched according to the communication purpose. Thus, if the device can switch the type of preamble used in the communication according to the communication purpose, then even when the communication purpose is switched, the preamble used in the communication can be appropriately set according to the communication purpose.

[0100] Similarly, unlike this embodiment, the radar communication device 50 operates as a slave communication device 20 that performs data communication with the master communication device 10 after initial startup. If the master communication device 10 instructs the user to switch the communication purpose from data communication to radar communication via data communication with the master communication device 10, then it can also be a structure that switches the communication purpose from data communication to radar communication. Such a radar communication device 50, for example, includes a storage unit that stores a data table showing the correspondence between the communication purpose and the type of preamble used in the communication, as well as the current setting of at least one of the communication purpose and the type of preamble. The type of preamble used in the communication can be switched according to the communication purpose. Thus, if the structure allows switching the type of preamble used in the communication based on the communication purpose, then even when the communication purpose is switched, the preamble used in the communication can be appropriately set according to the communication purpose.

[0101] <3. Blocking Mode>

[0102] The master communication device 10 and slave communication device 20 of the communication system SYS1 can each be configured to select a masking mode. By combining the preamble determination and masking mode described above, the communication success rate in high-priority applications can be further improved.

[0103] Here, refer to Figure 6 as well as Figure 7 A summary of the radio wave interference countermeasures in the communication system SYS1 is provided. Figure 6 This is a diagram illustrating the problems encountered during reception in UWB communication. Figure 7This is a schematic diagram outlining the radio wave interference countermeasures in the communication system SYS1. Additionally, in Figure 7 In this diagram, "master" refers to the master communication device 10, and "slave" refers to the slave communication device 20. The same abbreviated representation is sometimes used in other diagrams as well.

[0104] exist Figure 6 In this context, the target wave is the radio wave intended to be received by the receiving antenna RA1. The interference wave is the radio wave that is not intended to be received by the receiving antenna RA1. In UWB communication, the strength of the radio wave also has an impact, but generally, the earlier received radio waves are processed first. Specifically, the communication device enters the synchronization processing of the preceding radio wave and cannot process subsequent radio waves. Figure 6 In this scenario, two radio waves arrive at the receiving antenna RA1 in the order of interference wave and target wave. Therefore, the interference wave is processed first. In the receiving device, if the interference wave is received first, it cannot be identified as interference if the address in the PHR, which is processed following the preamble and SFD, is not demodulated. Alternatively, if it is identified as interference, processing for the interference wave is stopped, and processing for other waves (such as subsequent target waves) can be performed. Before the radio wave is determined to be interference through reception processing, there is a possibility that the target wave will arrive at the receiving antenna RA1, resulting in a missed reception of the target wave. In this embodiment, countermeasures are implemented to reduce communication failures caused by such radio wave interference. (Refer to...) Figure 7 A summary of the countermeasures is provided.

[0105] like Figure 7 As shown, the main communication device 10 and the slave communication device 20 can each select a receive mode, a transmit mode, or a shielded mode. In receive mode, each device 10 and 20 can receive data. In transmit mode, each device 10 and 20 can transmit data. Shielded mode is neither receive nor transmit mode; in shielded mode, each device 10 and 20 cannot communicate. Furthermore, shielded mode is a so-called idle mode where necessary circuitry is powered, allowing immediate transition to receive or transmit modes.

[0106] exist Figure 7 In the middle, τ start This is the moment when communication devices 10 and 20 begin receiving mode (receive mode start time). Furthermore, τ next This is the assumed time of receiving the target wave (assumed reception time), which follows the agreement between communication devices 10 and 20. Reception mode start time τ start Set to receive the assumed time τ next A little earlier. For example... Figure 7As shown, the master communication device 10 switches from a shielded mode to a receive mode immediately before the agreed-upon receive assumption time between itself and the slave communication device 20. The slave communication device 20 switches from a shielded mode to a receive mode immediately before the agreed-upon receive assumption time between itself and the master communication device 10. That is, in the communication method using wireless communication of this embodiment, a switch is performed from a shielded mode (where wireless communication is not possible) to a receive mode (where wireless communication is possible) immediately before the agreed-upon receive assumption time between the multiple devices 10 and 20 performing wireless communication. Furthermore, in the communication device using wireless communication of this embodiment, a switch from a shielded mode to a receive mode is performed immediately before the agreed-upon receive assumption time between itself and other devices performing wireless communication. In addition, the switching process immediately before the agreed-upon receive assumption time can also be performed when switching from a transmit mode to a receive mode.

[0107] This structure increases the probability that the device receiving the target wave is in shielded mode when interference waves arrive. That is, it reduces the likelihood of receiving interference waves and increases the probability of successfully receiving the target wave. This improves the success rate of wireless communication. Furthermore, it is preferable that the start time of the receiving mode is as close as possible to the assumed time of target wave reception. Detailed examples related to this will be described later.

[0108] <4.Main communication device>

[0109] Figure 8 This is a diagram showing an example of the structure of the main communication device 10. Additionally, in Figure 8 The diagram shows the structural elements required to illustrate the features of this embodiment, while descriptions of general structural elements are omitted.

[0110] like Figure 8 As shown, the main communication device 10 includes a wireless communication unit 11 and a controller 12.

[0111] Wireless communication unit 11 communicates wirelessly with slave communication device 20. Specifically, wireless communication unit 11 is composed of a UWB communication device that communicates with slave communication device 20 via UWB. Wireless communication unit 11 can receive in receive mode, can transmit in transmit mode, and cannot communicate in shielded mode, which is neither receive nor transmit mode.

[0112] The controller 12 includes a processor for performing calculations and other processing. The processor may, for example, include a CPU (Central Processing Unit). The controller 12 may consist of one processor or multiple processors. In the case of multiple processors, these processors can be interconnected and communicate with each other. Furthermore, the controller 12 includes computer components such as memory (RAM and ROM, etc.) required for executing programs.

[0113] The controller 12 includes a plan creation unit 121, a plan provision unit 122, and a plan execution unit 123 as its functions. Each functional unit 121 to 123 can be implemented, for example, by a processor executing a calculation process based on a program. However, it is not limited to this structure; each functional unit 121 to 123 can also be implemented, for example, by a processor executing a calculation process based on a different program for each functional unit.

[0114] Furthermore, as mentioned above, each functional unit 121-123 can be implemented by having the processor execute a program, i.e., by software, but it can also be implemented by other methods. At least a portion of each functional unit 121-123 can also be implemented using, for example, an ASIC (Application Specific Integrated Circuit) or a FPGA (Field Programmable Gate Array). That is, each functional unit 121-123 can also be implemented in hardware using a dedicated IC, etc. In addition, each functional unit 121-123 can also be implemented using both software and hardware. Furthermore, each functional unit 121-123 is a conceptual structural element. The functions performed by one structural element can be distributed among multiple structural elements. In addition, the functions of multiple structural elements can be combined into one structural element.

[0115] The planning creation unit 1121 creates a plan (hereinafter, referred to as a wireless communication plan) for UWB communication between the master communication device 10 and the slave communication devices 20. The wireless communication plan includes the timing of signal transmission and reception in each communication device 10, 20. In this embodiment, there are multiple slave communication devices 20. Therefore, the planning creation unit 1121 generates a wireless communication plan between the master communication device 10 and each slave communication device 20a to 20d.

[0116] The planning unit 122 provides the wireless communication plan created by the planning creation unit 121 to the slave communication devices 20. In this embodiment, there are multiple slave communication devices 20. Therefore, the planning unit 122 transmits the wireless communication plan to each slave communication device 20a to 20d. The transmission of the wireless communication plan to each slave communication device 20a to 20d may also be performed separately for each slave communication device 20a to 20d. However, in this embodiment, the planning unit 122 performs a broadcast transmission that is simultaneously transmitted to multiple slave communication devices 20a to 20d.

[0117] The planning execution unit 123 executes wireless communication according to the wireless communication plan created by the planning creation unit 1121. During the execution of wireless communication, the planning execution unit 123 controls the communication mode of the wireless communication unit 11.

[0118] Figure 9 This is a flowchart illustrating an example of the operation of the main communication device 10. Figure 9 The action shown begins, for example, when the body ECU, which controls the body of vehicle C1, is started. Specifically, the body ECU controls vehicle-mounted devices other than the engine and other vehicle driving system devices. These vehicle-mounted devices, other than the vehicle driving system devices, include, for example, air conditioning, door locking systems, window opening and closing systems, and windshield wiper systems.

[0119] Furthermore, as a representative example, the start-up timing of the vehicle's ECU is the timing when the vehicle's doors (C1) are unlocked. Other examples include the timing of ACC activation based on the operation of the vehicle's ignition key. This is also relevant when applying communication systems to other mobile bodies (e.g., trains, ships, aircraft). Figure 9 The timing of the start of the action shown becomes the timing of the start operation of the moving body drive system, etc. Furthermore, Figure 9 The actions shown can also be performed after the vehicle ECU is started, for example as periodic actions (e.g., actions performed immediately after startup, actions performed at given time intervals), or as exceptional actions (e.g., actions performed in the event of a communication failure, an increase in communication failures, or changes in the vehicle (communication) environment). Furthermore, at least one of the main communication device 10 and the secondary communication devices 20a-20d can be a vehicle ECU, or all of the main communication device 10 and the secondary communication devices 20a-20d may not be vehicle ECUs. A vehicle ECU can be, for example, an entertainment device such as an audio device.

[0120] In step S1, the planning creation unit 121 creates a wireless communication plan. The wireless communication plan includes the data transmission time from the main communication device 10 to each of the slave communication devices 20a-20d, and the data reception time from each of the slave communication devices 20a-20d by the main communication device 10. When a wireless communication plan is created, the process proceeds to the next step, S2. Furthermore, the main communication device 10 has information related to the wireless communication connections of each of the slave communication devices 20a-20d, which are the targets of wireless communication, set and registered (stored) by the administrator of the main communication device 10. In addition, when a new target device for wireless communication is added, the administrator sets and registers (stores) the added device.

[0121] In step S2, the planning unit 122 broadcasts (simultaneously transmits) the wireless communication plan to all slave communication devices 20a to 20d. That is, in this embodiment, the communication system SYS1 (vehicle communication system) agrees on the assumed reception time between the master communication device 10 and the slave communication devices 20 at the start of vehicle use. The transmission of the wireless communication plan follows the communication frame format of the UWB communication described above (see...). Figure 2 (This is used for broadcasting.) The wireless communication plan is included in the data body of the communication frame format.

[0122] Figure 10 This is a diagram illustrating an example of a data format for a wireless communication plan. For example... Figure 10 As shown, the data format of the wireless communication plan has a structure that connects time data D1, first data D2a, second data D2b, third data D2c, fourth data D2d and periodic data D3 in sequence.

[0123] Time data D1 represents the actual time of broadcast transmission (hereinafter, referred to as the broadcast transmission time). The broadcast transmission time is timed by the controller 12 based on a timer (not shown) built into the main communication device 10. Furthermore, the timer consists of a counter or the like that that counts at fixed time intervals based on the operating clock.

[0124] The first data D2a is data related to the first slave communication device 20a. The second data D2b is data related to the second slave communication device 20b. The third data D2c is data related to the third slave communication device 20c. The fourth data D2d is data related to the fourth slave communication device 20d.

[0125] Each set of data D2a to D2d has an ID data D21 and a time data D22 connected sequentially. ID data D21 represents the ID (identification information) of each of the communication devices 20a to 20d. Time data D22 is data representing time intervals based on broadcast transmission times, etc., and is related to the transmission time of data from the main communication device 10 and the reception time of data from the main communication device 10. The aforementioned transmission and reception times are expressed, for example, as a few milliseconds after the broadcast transmission time. The transmission and reception times are not transmitted at specific times because there is a possibility of inconsistencies in the identification times among the communication devices 10, 20a to 20d.

[0126] Periodic data D3 represents the communication timing period between the master communication device 10 and each slave communication device 20a-20d (e.g., refer to...). Figure 14 The data shown is for the period T.

[0127] return Figure 9 When the wireless communication plan is broadcast, the process proceeds to the next step, S3.

[0128] In step S3, the plan providing unit 122 determines whether any of the slave communication devices 20a-20d that sent the wireless communication plan have received a response. A response is a reply indicating that the wireless communication plan has been received, and it is a processing of requests from each slave communication device 20a-20d that received the wireless communication plan. This request is included in the data of the aforementioned wireless communication plan, so a response is made as long as the slave communication device 20 that received the wireless communication plan has not malfunctioned. However, due to reasons such as the aforementioned radio wave interference, some slave communication devices 20a-20d may be unable to receive the wireless communication plan. In particular, before broadcasting, since each slave communication device 20a-20d does not have a wireless communication plan, it is impossible to switch from the shielded mode to the receiving mode at the appropriate timing. Therefore, it needs to remain in the receiving mode for a long period, making it susceptible to radio wave interference.

[0129] If a response is received from all slave communication devices 20a-20d (Yes in step S3), the process proceeds to step S4. Conversely, if no response is received from any of the slave communication devices 20a-20d (No in step S3), the process returns to step S1. That is, if no response to the wireless communication plan is received from all devices 20a-20d that are the recipients of the broadcast, the wireless communication plan is broadcast again. This structure prevents the wireless communication plan from being executed when the master communication device 10 has not properly transmitted the wireless communication plan to the slave communication device 20. Furthermore, if the wireless communication plan is rebroadcast with a period D3, the timing result of the reception mode for each slave communication device 20a-20d based on the wireless communication plan during the rebroadcast is the same. Therefore, communication timing with each slave communication device 20a-20d can be set not only when a response is received from all slave devices through the same broadcast, but also when a response is received from all slave devices through multiple broadcasts.

[0130] In step S4, the planning unit 122 determines the wireless communication plan. When the wireless communication plan is determined, the process proceeds to the next step S5.

[0131] In step S5, the planning execution unit 123 begins wireless communication processing according to the wireless communication plan. A specific example of wireless communication processing according to the wireless communication plan will be described later.

[0132] Furthermore, in the structure of this embodiment, for example, if at least any of the multiple communication devices 20a to 20d malfunctions, the process in step S3 will not be "yes," and the wireless communication plan cannot be determined at any time. Considering this, for example, if even after a given number of broadcast transmissions (e.g., 3 times), the process in step S3 does not become "yes," an error can be reported. Alternatively, as another example, the system can be configured to create a wireless communication plan that excludes the malfunctioning communication devices 20a to 20d, and perform corresponding wireless communication processing.

[0133] <5. From the communication device>

[0134] Figure 11 This is a diagram illustrating a structural example of the communication device 20. Additionally, in Figure 11 The diagram shows the structural elements necessary for illustrating the features of this embodiment, while descriptions of general structural elements are omitted. Furthermore, all of the multiple communication devices 20a to 20d possess... Figure 11 The structure shown. (As illustrated) Figure 11 As shown, the communication device 20 includes a wireless communication unit 21 and a controller 22.

[0135] Wireless communication unit 21 communicates wirelessly with main communication device 10. Specifically, wireless communication unit 21 is composed of a UWB communication unit that communicates UWB with main communication device 10 (wireless communication unit 11). Wireless communication unit 21 can receive in receive mode, can transmit in transmit mode, and cannot communicate in shielded mode, which is neither receive mode nor transmit mode.

[0136] The controller 22 includes a processor for performing calculations and other processing. The processor may, for example, include a CPU. The controller 22 may consist of one processor or multiple processors. In the case of multiple processors, these processors can be interconnected and communicate with each other. Furthermore, the controller 22 includes computer components such as memory (RAM and ROM, etc.) required for executing programs.

[0137] The controller 22 includes a planning acquisition unit 221 and a planning execution unit 222 as its functions. Each functional unit 221 and 222 can be implemented, for example, by a processor executing a calculation process based on a program. However, it is not limited to this structure; each functional unit 221 and 222 can also be implemented, for example, by a processor executing a calculation process based on a different program for each functional unit.

[0138] Furthermore, as described above, each functional unit 221 and 222 can be implemented by having the processor execute a program, i.e., by software, but it can also be implemented by other methods. At least a portion of each functional unit 221 and 222 can also be implemented using, for example, an ASIC or an FPGA. That is, each functional unit 221 and 222 can also be implemented in hardware using a dedicated IC or the like. In addition, each functional unit 221 and 222 can also be implemented using both software and hardware. Furthermore, each functional unit 221 and 222 is a conceptual structural element. The functions performed by one structural element can be distributed among multiple structural elements. In addition, the functions of multiple structural elements can be combined into one structural element.

[0139] The planning acquisition unit 221 acquires the wireless communication plan provided by the main communication device 10 via the wireless communication unit 21. The planning acquisition unit 221 can perform necessary processing on the acquired wireless communication plan as appropriate. For example, it can perform processing to convert the time data contained in the transmission data broadcast from the main communication device 10 into the time of this device.

[0140] The planning execution unit 222 executes wireless communication based on the wireless communication plan obtained by the planning acquisition unit 221. During the execution of wireless communication, the planning execution unit 222 controls the communication mode of the wireless communication unit 21.

[0141] Figure 12 This is a flowchart illustrating an example of the operation of the communication device 20. Furthermore, in this embodiment, there are multiple communication devices 20, but each of the communication devices 20a to 20d performs the same operation. Figure 12 The actions shown are in conjunction with the actions of the main communication device 10 described above (see reference). Figure 9 And so it begins. That is, Figure 12 The actions shown, for example, begin when the vehicle's ECU is started. Furthermore, Figure 12 The actions shown can also be performed after the vehicle's ECU is started, for example, as a periodic action or an exceptional action.

[0142] In step S11, the plan acquisition unit 221 determines whether a wireless communication plan has been received. If a wireless communication plan has been received (yes in step S11), the process proceeds to the next step, S12. On the other hand, if no wireless communication plan has been received (no in step S11), the process of step S11 is repeated. That is, in step S11, it monitors whether a wireless communication plan has been received.

[0143] In step S12, the plan acquisition unit 221 responds to the receipt of the wireless communication plan. Specifically, the plan acquisition unit 221 responds to the response request from the master communication device 10, which includes data containing the wireless communication plan, indicating that the wireless communication plan has been received. This response is made by transmitting UWB communication from the slave communication device 20 to the master communication device 10. If the response to the receipt of the wireless communication plan is complete, the process proceeds to the next step, S13.

[0144] In step S13, the planning acquisition unit 221 converts the transmission time and reception time (e.g., time expressed in the form of a few milliseconds later) based on the broadcast transmission time and other information included in the wireless communication plan into the time of this device. The planning acquisition unit 221 performs time conversion processing based on a timer (not shown) built into this device. When the time conversion processing is completed, the process proceeds to the next step S14.

[0145] In step S14, the planning acquisition unit 221 determines a wireless communication plan. Alternatively, the processing in step S14 can be performed before the processing in step S13. When the wireless communication plan is determined, the process proceeds to the next step, S15.

[0146] In step S15, the planning execution unit 222 begins wireless communication processing according to the wireless communication plan. A specific example of wireless communication processing according to the wireless communication plan will be described later.

[0147] <6. Examples of the operation of a communication system based on a wireless communication plan>

[0148] Next, an operational example of the communication system SYS1 according to the wireless communication plan will be explained. During the communication processing of data according to the wireless communication plan, the start time τ of the receiving mode in the master communication device 10 and the slave communication device 20 is... start As mentioned above, the assumed receiving time τ is set as follows. next Follow closely. Additionally, the start time τ of the receive mode. start This is the moment of switching from shielded mode to receive mode. Furthermore, the assumed receive time τ... next The switching process for receiving mode can also be performed after the broadcast is sent, when the master communication device 10 receives a response from the slave communication device 20.

[0149] Receive assumption time τ next The calculation is based on a wireless communication plan broadcast from any of the multiple devices 10, 20a to 20d. Furthermore, in this embodiment, as described above, the wireless communication plan is broadcast from the main communication device 10. (Reception assumption time τ) next The timing is obtained through an agreement between the main communication device 10 and each of the slave communication devices 20a to 20d according to the wireless communication plan. With this structure, accurate reception timing in accordance with the communication plan can be obtained, and the start time of the reception mode can be appropriate.

[0150] To avoid interference from interfering waves, it is preferable to receive at the assumed time τ. next Immediately following the start time τ of the receive mode execution start In this embodiment, the timing of the start of the receiving mode is set at a time τ that takes this into account. start The structure. Figure 13 It is used to describe the start time τ of the receive mode. start A detailed example of the setting method is illustrated in the diagram.

[0151] In UWB communication standards, the transmission and reception times (moments) can be obtained at the PHR timing. Considering this, in this embodiment, as... Figure 13 As shown, the assumed receiving time τ next The PHR (Presentation Response Time) is determined based on the frame format used for wireless communication. Therefore, in UWB wireless communication, the start time τ of the receive mode can be easily determined. start The timing is set to an appropriate level to reduce the probability of interference from interfering waves. Specifically, the assumed receiving time τ... next The start timer is set for PHR.

[0152] In this embodiment, the assumed time τ is received. next The moment immediately preceding the start of the receiving mode is τ. start It is determined by the following formula (1).

[0153] τ start =τ next -(t) SFD +t sym ×N rg (1)

[0154] In equation (1), t SFD This refers to the reception period (SFD time) of the SFD contained in the frame format. sym N is the reception period (one symbol time) of one symbol of the preamble signal code in the preamble contained in the frame format. As mentioned above, one symbol of the preamble signal code refers to a sequence of symbols constructed using pulses of a given pattern (e.g., -, 0, +). rg This is the necessary number of recognitions for one symbol of the preamble signal code. Communication devices 10 and 20 only require the necessary number of recognitions N. rg UWB communication data can only be received after recognizing one symbol of the preamble signal code. Additionally, the required number of recognition attempts N... rg The number of times is determined by devices 10 and 20 (the number of times the equipment depends). In Figure 13 In the example shown, as a case study, the required number of recognitions N rg It is 4 times. By analyzing t... sym Multiply by the number of necessary identifications required by the device. rg This allows for the calculation of the minimum recognition period for the preamble. In this embodiment, it is compared to the assumed reception time τ. next Even earlier, the operation formula (t) SFD +t sym ×N rg The time interval obtained is called the start time τ of the receiving mode. start .

[0155] By determining the start time of the receive mode in this way, the start of the period during which UWB communication data can be received can be set as close as possible to the assumed receive time. This reduces the possibility of interference from interfering waves and improves the communication success rate. Furthermore, the start time of the receive mode τ... start Alternatively, it can be set to be compared to the received assumption time τ. next Early by the operation formula (t) SFD +t sym ×N rg The time period (time) obtained should be the time of the margin obtained earlier through experiments, etc.

[0156] Figure 14 This is a schematic diagram illustrating an example of the operation of the communication system SYS1 according to the wireless communication plan. Figure 14 The action shown is related to Figure 9 Step S5 and Figure 12The action corresponding to the execution of the wireless communication plan in step S15. Figure 14 In the case where the main communication device 10 and each of the slave communication devices 20a to 20d are neither in transmitting mode nor receiving mode, they become shielded mode.

[0157] In addition, Figure 14 In this example, the communication is configured such that, according to the wireless communication plan, the given wireless communication between the main communication device 10 and each of the four slave communication devices 20a-20d is repeated sequentially with a period T. However, this is merely an example. Alternatively, according to the wireless communication plan, the given wireless communication between the main communication device 10 and each of the four slave communication devices 20 may only be performed once sequentially. Furthermore, the number of slave communication devices 20 that periodically communicate with the main communication device 10 can be appropriately varied, and it is also possible for a portion of all the slave communication devices 20a-20d included in the communication system SYS1 to periodically communicate with the main communication device 10.

[0158] exist Figure 14 In the example shown, the master communication device 10 first initiates a transmission mode according to the wireless communication plan. Then, after the transmission time (transmission time Ta) agreed upon with the first slave communication device 20a through the wireless communication plan elapses from the aforementioned broadcast transmission time, the master communication device 10 transmits a signal to the first slave communication device 20a. This transmitted signal may include, for example, instruction information to the first slave communication device 20a. Furthermore, the master communication device 10 terminates the transmission mode at a pre-programmed time, based on the start timing of the transmission mode and the time required for data transmission (depending on the capacity of the transmitted data, etc.).

[0159] The assumed reception time τ is determined by the first slave communication device 20a according to the aforementioned transmission time Ta agreed upon with the first slave communication device 20a through the wireless communication plan. next The start time τ of the receiving mode is obtained by equation (1). start Then, the first communication device 20a starts receiving the mode at the determined start time τ. start A switching process is performed from shielding mode to receiving mode. As a result, the first slave communication device 20a tries its best to avoid receiving interference waves and receives the transmission waves sent from the master communication device 10.

[0160] The first time the communication device 20a enters receiving mode, τ startBased on the timing pre-programmed in the device 20a, the first slave communication device 20a sequentially executes the end of the receiving mode, the start of the transmitting mode, and the end of the transmitting mode. After starting the transmitting mode, the first slave communication device 20a transmits a signal to the main communication device 10 after a time Ta1 agreed upon between the wireless communication plan and the main communication device 10, starting from the transmitting timing of the main communication device 10 (referring to the transmitting time Ta). The transmitted signal includes, for example, sensor information obtained by a sensor provided by the first slave communication device 20a. In addition, based on the starting timing of the transmitting mode, the first slave communication device 20a ends the transmitting mode at a timing pre-programmed in the device 20a, determined by the time required for data transmission (depending on the amount of data to be transmitted, etc.).

[0161] The master communication device 10 determines the assumed reception time τ based on the aforementioned time Ta1 agreed upon with the first slave communication device 20a via a wireless communication plan. next The start time τ of the receiving mode is obtained by equation (1). start Then, the main communication device 10 determines the start time τ of the received mode. start A switching process is performed from shielded mode to receiving mode. As a result, the main communication device 10 tries its best to avoid receiving interference waves and receives the transmission wave sent from the first slave communication device 20a.

[0162] Thus, in the wireless communication plan, the communication between the master communication device 10 and the first slave communication device 20a, as defined by the first time slot TS1, ends. Upon the end of the first time slot TS1, the communication between the master communication device 10 and the second slave communication device 20b, as defined by the second time slot TS2, is executed using the same steps as in the first time slot TS1. Furthermore, upon the end of the second time slot TS2, the communication between the master communication device 10 and the third slave communication device 20c, as defined by the third time slot TS3, is executed using the same steps as in the first time slot TS1. Furthermore, upon the end of the third time slot TS3, the communication between the master communication device 10 and the fourth slave communication device 20d, as defined by the fourth time slot TS4, is executed using the same steps as in the first time slot TS1. When the fourth time slot TS4 ends, one cycle T, consisting of the four time slots TS1 to TS4, ends, and the first time slot TS1 of the next cycle begins.

[0163] Furthermore, in the second time slot TS2, the master communication device 10 transmits a signal to the second slave communication device 20b after the transmission time agreed upon with the second slave communication device 20b (transmission time Tb) from the transmission time of the broadcast transmission. The second slave communication device 20b then transmits a signal at the start time τ of the reception mode, determined by the aforementioned transmission time Tb. startThe process involves switching from shielding mode to receiving mode. Furthermore, the second slave communication device 20b, which receives the transmitted wave from the main communication device 10, transmits a signal to the main communication device 10 after a time Tb1 (not shown) agreed upon with the main communication device 10, elapsed from the transmission timing (referring to transmission time Tb) of the main communication device 10. The main communication device 10 then initiates the receiving mode at the start time τ determined by the aforementioned time Tb1. start It performs a switching process from shielding mode to receiving mode.

[0164] Furthermore, in the third time slot TS3, the master communication device 10 transmits a signal to the third slave communication device 20c after the transmission time agreed upon with the third slave communication device 20c (transmission time Tc) from the transmission time of the broadcast transmission. The third slave communication device 20c then transmits a signal at the start time τ of the reception mode, determined by the aforementioned transmission time Tc. start The process involves switching from shielding mode to receiving mode. Furthermore, the third slave communication device 20c, which receives the transmitted wave from the main communication device 10, transmits a signal to the main communication device 10 after a time Tc1 (not shown) agreed upon with the main communication device 10, elapsed from the transmission timing (referring to transmission time Tc) of the main communication device 10. The main communication device 10 then initiates the receiving mode at the start time τ determined by the aforementioned time Tc1. start It performs a switching process from shielding mode to receiving mode.

[0165] Furthermore, in the fourth time slot TS4, the master communication device 10 transmits a signal to the fourth slave communication device 20d after a time (transmission time Td) agreed upon with the fourth slave communication device 20d has elapsed since the transmission time of the broadcast transmission. The fourth slave communication device 20d then transmits a signal at the start time τ of the reception mode, determined by the aforementioned transmission time Td. start The process involves switching from shielding mode to receiving mode. Furthermore, the fourth slave communication device 20d, which receives the transmitted wave from the main communication device 10, transmits a signal to the main communication device 10 after a time Td1 (not shown) agreed upon with the main communication device 10, elapsed from the transmission timing (referring to transmission time Td) of the main communication device 10. The main communication device 10, at the receiving mode start time τ determined by the aforementioned time Td1... start It performs a switching process from shielding mode to receiving mode.

[0166] As can be seen from the above, in this embodiment, the communication between the main communication device 10 and each of the slave communication devices 20a to 20d is carried out at different times, thus avoiding radio wave interference between these communications.

[0167] Furthermore, in this embodiment, the main communication device 10, which broadcasts the wireless communication plan, receives the data after transmitting the wireless communication-based data according to the plan. Moreover, when receiving the data after transmitting the wireless communication-based data, the time τ calculated by equation (1) is... start The system switches to receive mode. This allows for signal reception, minimizing interference waves, not only on the receiving side of the wireless communication plan but also on the transmitting side.

[0168] Furthermore, in this embodiment, the main communication device 10 is configured to communicate in the order of transmission and reception in each time slot TS1 to TS4. However, this is only an example, and the main communication device 10 may also communicate in the order of reception and transmission in each time slot TS1 to TS4. In this case, in each time slot TS1 to TS4, it is necessary to reverse the order of transmission and reception from communication devices 20a to 20d compared to the order in this embodiment.

[0169] <7. Variations>

[0170] [7-1. First Variation Example]

[0171] Figure 15 This is a diagram showing the structure of the communication system SYS1A involved in the first variation. Figure 16 This diagram illustrates the relationship between the master communication device 10A and the slave communication devices 20A in the communication system SYS1A involved in the first modification example. Furthermore, in this modification example, there are multiple slave communication devices 20A (specifically four), and each slave communication device 20aA, 20bA, 20cA, and 20dA can communicate with the master communication device 10A. Each slave communication device 20aA to 20dA has the same structure. Therefore, in Figure 16 Only the first slave communication device 20aA is shown, while the descriptions of the second slave communication device 20bA, the third slave communication device 20cA, and the fourth slave communication device 20dA are omitted.

[0172] exist Figure 15 as well as Figure 16 In the diagram, the thick line L1 is the communication line used for wired communication. That is, in the communication system SYS1A of the first modified example, the master communication device 10A and the slave communication device 20A can be configured to perform wired communication in addition to UWB wireless communication. Therefore, as... Figure 16 As shown, in addition to the wireless communication units 11 and 21 that are capable of UWB communication, the main communication device 10A and the slave communication device 20A also have wired communication units 13 and 23 that are capable of wired communication.

[0173] In this modified example, communication line L1 is a power line connecting the main communication device 10A and each of the slave communication devices 20aA to 20dA to the battery 70. That is, the wired communication between the main communication device 10A and each of the slave communication devices 20aA to 20dA is PLC (Power Line Communication) communication. However, the wired communication used in the communication system SYS1A is not limited to PLC communication, but can also be CAN (Registered Trademark, Controller Area Network) communication, LIN (Registered Trademark, Local Interconnect Network) communication, CXPI (Clock Extension Peripheral Interface) communication, etc.

[0174] In this variation, when broadcasting a wireless communication plan via the main communication device 10A, wired communication is used. That is, in this variation, in the aforementioned... Figure 9 In the process shown, the broadcast transmission of the wireless communication plan replaces UWB communication and is carried out using wired communication (PLC communication).

[0175] When the wireless communication plan is not transmitted to each communication device 20aA to 20dA, it is difficult to switch from shielded mode to receiving mode at the timing when UWB communication is least susceptible to radio interference. In this modified example, it is configured to use wired communication instead of wireless communication in situations where the possibility of radio interference is high. Therefore, the possibility of communication failure due to radio interference during reception can be reduced. In addition, the broadcast transmission of the wireless communication plan can also be carried out using both wireless and wired communication.

[0176] As described above, in this modified example, the wired communication is PLC communication using power line L1. Power line L1 is an indispensable wiring harness for supplying power to the main communication device 10A and the slave communication devices 20aA to 20dA. In other words, according to the structure of this modified example, wired communication can be achieved using a wiring harness that cannot be reduced, thus suppressing the increase in wiring harness while utilizing wired communication.

[0177] [7-2. Second variation]

[0178] Figure 17 This is a diagram showing the structure of the communication system SYS1B involved in the second variation. (See diagram for example.) Figure 17As shown, similar to the communication system SYS1 according to the above embodiment, the communication system SYS1B includes a master communication device 10B and multiple slave communication devices 20B. The multiple slave communication devices 20B include a first slave communication device 20aB, a second slave communication device 20bB, a third slave communication device 20cB, and a fourth slave communication device 20dB. Similar to the communication system SYS1 according to the above embodiment, the communication system SYS1B includes a ranging communication device 40 and a radar communication device 50, but... Figure 17 The diagrams of the ranging communication device 40 and the radar communication device 50 are omitted.

[0179] In this modified example, the controller 12B of the main communication device 10B, in addition to having the functional units 121 to 123 of the controller 12 in the above-described embodiment, also has a radio wave learning unit 124. The radio wave learning unit 124 is, for example, a functional unit implemented by a processor of the controller 12B performing computational processing according to a program. However, the radio wave learning unit 124 is not limited to a software-implemented structure; it can also be implemented in hardware using a dedicated IC or the like.

[0180] The radio wave learning unit 124 determines (calibrates) the optimal value of the radio wave output for the wireless communication (UWB communication) used between the main communication device 10B and each of the slave communication devices 20aB to 20dB. In this modified example, the optimal value is the minimum required output of the radio wave. By setting the radio wave output to the minimum required level, the power consumption in the communication system SYS1B can be reduced. Furthermore, by setting the radio wave output to the minimum required level, the possibility of interference with other communications can be reduced.

[0181] In this modified example, when the radio wave output is calibrated by the radio wave learning unit 124, UWB communication is performed between the main communication device 10B and each of the slave communication devices 20aB to 20dB. Furthermore, the device is configured to perform a switch to the receiving mode (switching from the shielded mode) immediately following the reception assumption time agreed upon between the devices when calibrating the output of the radio waves used between the devices.

[0182] Therefore, the calibration of radio wave output can be performed while suppressing the effects of radio wave interference. That is, wireless communication for calibration can be performed without the influence of radio wave interference, and the calibration of radio wave output can be performed quickly and accurately. In addition, the calibration of radio wave output can also be performed outside of devices with a master-slave relationship. Moreover, in this case, a switch to the receiving mode can be performed immediately before the agreed receiving assumption time between the devices.

[0183] Figure 18 This is a flowchart illustrating an example of the processing performed by the main communication device 10B (radio wave learning unit 124) during the calibration of radio wave output.Figure 19 It is used to explain the execution Figure 18 The diagram shows the operation of the communication device 20B during processing.

[0184] Radio wave output calibration (radio wave learning) is performed, for example, at the start of use of the SYS1B communication system. Radio wave output calibration may also begin, for example, during the startup of the aforementioned vehicle ECU. Radio wave output calibration is typically performed before the broadcast transmission of a planned wireless communication operation.

[0185] Furthermore, the calibration of the radio wave output is performed sequentially between the main communication device 10B and each of the slave communication devices 20aB to 20dB. While there is no specific requirement for the order, for example, the main communication device 10B calibrates the radio wave output in the order of the first slave communication device 20aB, the second slave communication device 20bB, the third slave communication device 20cB, and the fourth slave communication device 20dB. During each calibration, the following steps are performed: Figure 18 as well as Figure 19 The processing shown.

[0186] like Figure 18 As shown, in step S21, the master communication device 10B performs a ranging process to determine the distance between itself and the slave communication device 20B. Furthermore, the ranging process can utilize known methods. In the ranging process, the master communication device 10B sends a ranging signal to the slave communication device 20B using UWB communication. The slave communication device 20B responds based on the received ranging signal (see reference). Figure 19 If the time required for the radio wave to travel between the devices is obtained from this exchange, then the speed of the radio wave is known, and therefore the distance X between the master communication device 10B and the slave communication device 20B can be calculated.

[0187] Furthermore, the radio wave output of the UWB communication used in the ranging process is preferably close to the maximum power specified in the communication standard (e.g., -41.3 dBm / MHz). "Close to maximum power" means the same value as the maximum power or a value slightly smaller than the maximum power. By setting the radio wave output during ranging processing to close to the maximum power, the probability of radio waves failing to reach the slave communication device 20B can be reduced, thereby increasing the success rate of the ranging process.

[0188] When the distance X is calculated through the ranging process, the main communication device 10B causes the process to proceed to step S22.

[0189] In step S22, the main communication device 10B determines the range of transmission power (output range) to be used in order to find the optimal value of the radio wave output. When determining the range of transmission power, a correlation diagram showing the relationship between pre-created inter-device distance and transmission power (radio wave output) is used. Figure 20This is an example of a correlation diagram showing the relationship between the distance between devices and the transmission power. The correlation diagram is a mapping created through experiments, etc., but due to characteristic deviations of each device, environmental variations such as temperature, etc., the transmission power calculated from the correlation diagram may not be the optimal value. Therefore, calibration is performed to determine the optimal value for the radio wave output.

[0190] The main communication device 10B, based on the distance X and correlation diagram obtained in step S21 (refer to...), Figure 20 First, the transmission power Y, which is most likely to be close to the optimal value, is determined. Then, the main communication device 10B uses the determined transmission power Y as a reference to determine the minimum value a and the maximum value b of the transmission power (refer to...). Figure 20 The minimum value 'a' and the maximum value 'b' can be determined using pre-prepared tables and formulas. Once the range of transmission power is determined, the main communication device 10B initiates the process to step S23.

[0191] In step S23, the main communication device 10B sets variable N to 1. If variable N is set to 1, the main communication device 10B causes the process to proceed to step S24.

[0192] In step S24, the main communication device 10B transmits UWB radio waves to the slave communication device 20B at the Nth power. The Nth power is determined according to a preset reference. In this modified example, the Nth power is the power obtained by adding a predetermined step power α multiplied by (N-1) times the minimum value 'a' of the transmission power range. That is, for example, in the case of N=1 (i.e., the initial transmission for power adjustment), the Nth power is "a". Furthermore, for example, in the case of N=2, the Nth power is "a+α". Furthermore, for example, in the case of N=3, the Nth power is "a+2α". In addition, in this example, the transmission power is gradually increased based on the minimum value 'a' of the transmission power range, but this is only an example. A structure that gradually decreases the transmission power based on the maximum value 'b' of the transmission power range can also be used. When transmitting at the Nth power, the main communication device 10B causes the process to proceed to step S25.

[0193] In step S25, the master communication device 10B determines whether a reply has been received from the slave communication device 20B within a given period determined through experiments, etc. The slave communication device 20B responds when it receives a transmitted wave from the master communication device 10B. However, if the transmission power of the transmitted wave from the master communication device 10B is low, sometimes the transmitted wave may not reach the slave communication device 20B. In this case, the master communication device 10B does not receive a reply from the slave communication device 20B. Furthermore, in... Figure 19In the example shown, the first and second transmission powers are not received by the communication device 20B, and the communication device 20B does not respond. On the other hand, the third transmission power is received by the communication device 20B, and the communication device 20B responds.

[0194] If the slave communication device 20B responds (Yes in step S25), the master communication device 10B proceeds to step S26. On the other hand, if the master communication device 10B does not respond (No in step S25), the master communication device 10B proceeds to step S28.

[0195] In step S26, the main communication device 10B determines the output power of the transmitted wave. For example, the main communication device 10B uses the power received from the slave communication device 20B, i.e., the Nth power, as the output power. Alternatively, as another example, the main communication device 10B adds a margin determined through experiments to the Nth power to obtain the output power. Figure 19 In the example shown, the output power is either the third power (a+2α) or the third power. The power with margin power is set as (a+2α) as the third power. When the output power is determined, the main communication device 10B causes the processing to proceed to step S27.

[0196] In step S27, the master communication device 10B uses UWB communication, employing the output power determined for the slave communication device 20B as the utilization power for communication. Thus, UWB communication can be performed between the master communication device 10B and the slave communication device 20B at the determined output power.

[0197] In step S28, the main communication device 10B increments the variable N by 1. While incrementing the variable N, the main communication device 10B returns the process to step S24. Thus, the main communication device 10B can output a transmission wave while simultaneously changing the output power.

[0198] In this modified example, the configuration is such that when performing the calibration of the radio wave output as described above, Figure 19 During the ranging process (represented by dashed box W1) and the output power adjustment process (represented by dashed box W2), the assumed receiving time τ is used. next The switch to receiving mode follows immediately.

[0199] For example, before transmitting the signal (ranging signal) used for ranging processing, the master communication device 10B and the slave communication device 20B pre-arrange an agreement related to the transmission time. This agreement can be performed using UWB communication, but it can also utilize the aforementioned PLC communication. Based on the agreement, the start time τ of the receiving mode in equation (1) above can be determined. startFor example, when transmitting radio waves from the main communication device 10B to the secondary communication device 20B, and when transmitting radio waves from the secondary communication device 20B to the main communication device 10B, the receiving device switches to the receiving mode just before the assumed reception time. Therefore, during ranging processing, the possibility of interference from radio waves can be reduced, enabling rapid and accurate distance measurement.

[0200] Furthermore, for example, before transmitting the signal used for output power adjustment processing, the master communication device 10B and the slave communication device 20B pre-arrange an agreement related to the transmission time. This agreement can be performed using UWB communication, but it can also utilize the aforementioned PLC communication. Based on the agreement, the receive mode start time τ of equation (1) above can be determined. start For example, when transmitting radio waves from the main communication device 10B to the secondary communication device 20B, and when transmitting radio waves from the secondary communication device 20B to the main communication device 10B, the receiving device switches to the receiving mode just before the assumed reception time. Therefore, during output power adjustment processing, the possibility of being affected by radio wave interference can be reduced, and the output power can be determined quickly and appropriately.

[0201] Figure 19 The ranging process, represented by the dashed box W1, is the preprocessing for data communication between the master communication device 10B and the slave communication device 20B. Therefore, the execution... Figure 19 The main communication device 10B and the slave communication device 20B, indicated by the dashed box W1 in the diagram, may be used for data communication rather than ranging communication. Alternatively, they may be configured to perform... Figure 19 The main communication device 10B and the slave communication device 20B, represented by the dashed box W1, are used for ranging communication during ranging processing. Figure 19 After the ranging process, indicated by the dashed box W1, the main communication device 10B and the slave communication device 20B switch the type of the preamble from the type corresponding to ranging communication to the type corresponding to data communication.

[0202] <8. Precautions, etc.>

[0203] The various technical features disclosed in this specification for carrying out the invention can be modified in various ways without departing from the spirit of the invention. Furthermore, the multiple embodiments and variations disclosed in this specification for carrying out the invention can be combined and implemented to the extent possible.

[0204] -Symbol Explanation-

[0205] 10, 10A, 10B... Main communication devices

[0206] 20, 20A, 20B... from communication devices

[0207] 20a, 20aA, 20aB... First slave communication device

[0208] 20b, 20bA, 20bB... Second communication device

[0209] 20c, 20cA, 20cB... Third communication device

[0210] 20dA, 20dB... Fourth communication device

[0211] 40. Ranging and Communication Device

[0212] 50... Radar communication devices

[0213] SYS1, SYS1A, SYS1B... communication system.

Claims

1. A communication method, wherein a first communication device and a second communication device use a preamble for communication. The first communication device communicates with the second communication device using a type of preamble determined from a plurality of types of preambles, which are determined by the pulse repetition frequency or the length of the preamble, according to the purpose of communication.

2. The communication method according to claim 1, wherein, The primary use takes precedence over the secondary use. The pulse repetition frequency determined when the purpose of the communication is the first purpose is higher than the pulse repetition frequency determined when the purpose of the communication is the second purpose.

3. The communication method according to claim 1, wherein, The primary use takes precedence over the secondary use. The length of the preamble, determined when the purpose of the communication is the first purpose, is longer than the length of the preamble, determined when the purpose of the communication is the second purpose.

4. The communication method according to claim 1, wherein, The pulse repetition frequency of the preamble and the length of the preamble are determined according to the intended use of the communication.

5. The communication method according to claim 4, wherein, The primary use takes precedence over the secondary use. The pulse repetition frequency determined when the purpose of communication is the first purpose is higher than the pulse repetition frequency determined when the purpose of communication is the second purpose. The length of the preamble, determined when the purpose of the communication is the first purpose, is longer than the length of the preamble, determined when the purpose of the communication is the second purpose.

6. The communication method according to claim 5, wherein, The first use is data communication, and the second use includes at least one of ranging communication or radar communication.

7. The communication method according to claim 1, wherein, The communication is a wireless communication based on UWB communication. The purpose of the communication includes at least one of the following: data communication, ranging communication, or radar communication.

8. The communication method according to claim 1, wherein, The pulse repetition frequency is 16MHz or 64MHz.

9. The communication method according to claim 1, wherein, The length of the preamble is any one of 16 symbols, 64 symbols, 128 symbols, 256 symbols, 512 symbols, 1024 symbols, 2048 symbols, or 4096 symbols.

10. The communication method according to claim 1, wherein, It is possible to switch the purpose of the communication.

11. The communication method according to any one of claims 1 to 10, wherein, Before the agreed reception assumption time between the first communication device and the second communication device, a switch is made from shielding mode to receiving mode. In shielding mode, wireless communication cannot be performed, while in receiving mode, the wireless communication is received.

12. A communication system comprising a first communication device and a second communication device, The first communication device communicates with the second communication device using a type of preamble determined from a plurality of types of preambles, which are determined by the pulse repetition frequency of the preamble or the length of the preamble, according to the intended use of the communication.

13. The communication system according to claim 12, wherein, The communication is a wireless communication based on UWB communication. The purpose of the communication includes at least one of the following: data communication, ranging communication, or radar communication.

14. The communication system according to claim 13, wherein, The first communication device and the second communication device are mounted on the vehicle.

15. A communication method for communication between a first communication device and a second communication device performing UWB communication. When the communication application is data communication, the first communication device sets the pulse repetition frequency to 64MHz. When the communication is used for ranging or radar communication, the first communication device sets the pulse repetition frequency to 16MHz. The first communication device communicates with the second communication device using the determined pulse repetition frequency.

16. A communication method for communication between a first communication device and a second communication device performing UWB communication. When the purpose of communication is data communication, the first communication device determines the length of the preamble to be 4096 symbols. When the communication is used for ranging or radar communication, the first communication device determines that the length of the preamble is less than 4096 symbols. The first communication device communicates with the second communication device using the determined preamble length.

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