JP7380156B2 - Mobile terminal distance estimation system and in-vehicle system - Google Patents

Description

The present disclosure relates to a mobile terminal distance estimating system and an in-vehicle system that estimate a distance from an in-vehicle communication device to a mobile terminal based on a propagation time of a signal from the mobile terminal to an in-vehicle communication device installed in a vehicle.

A method has been proposed in which three or more vehicle-mounted communication devices whose positions are known perform wireless communication with a mobile terminal such as a smartphone, thereby specifying the distance from each vehicle-mounted communication device to the mobile terminal. Furthermore, a method of estimating the position of a mobile terminal based on the distance from each in-vehicle communication device to the mobile terminal is also known. The distance from the in-vehicle communication device to the mobile terminal is calculated, for example, by multiplying the measured propagation time (in other words, flight time) of the radio wave by the speed of the radio wave. Note that positioning methods using the propagation time of radio waves include the TOA (Time Of Arrival) method and the TDOA (Time Difference Of Arrival) method.

In Patent Document 1, an in-vehicle system and a mobile terminal are configured to enable UWB (Ultra Wide Band) communication, and the in-vehicle system transmits an impulse signal used in UWB communication and then receives a response signal from the mobile terminal. A configuration is disclosed in which the distance of the mobile terminal to the vehicle is estimated based on the time it takes to reach the vehicle (hereinafter referred to as round trip time).

Patent No. 6093647

As disclosed in Patent Document 1, when estimating the relative position of the mobile terminal with respect to the vehicle using the propagation time of an impulse signal between the mobile terminal and the in-vehicle communication device, the measurement error of the propagation time is caused by the difference between the in-vehicle communication device and the mobile device. This has a large impact on the accuracy of estimating the distance (and therefore location) to the terminal. Specifically, if the propagation time shifts by just 1 nanosecond, the estimated distance from the in-vehicle communication device to the mobile terminal will shift by 30 centimeters.

The propagation time is the time from when one of the mobile terminal and the in-vehicle communication device transmits an impulse signal until the other detects that the impulse signal has been received. The process of detecting that an impulse signal has been received is a process of detecting that the strength of the received signal exceeds a threshold value.

There is a time difference between the time when the strength of the received signal exceeds the threshold and the time when the strength of the received signal reaches its peak. If the time difference between the detection time of the received signal and the peak time of the received signal is large, the distance error will become large.

The present disclosure has been made based on this situation, and its purpose is to provide a mobile terminal distance estimation system and an in-vehicle system that can accurately estimate the distance to a mobile terminal. be.

The object is achieved by the combination of features recited in the independent claims, and the subclaims define further advantageous embodiments. The numerals in parentheses described in the claims indicate correspondence with specific means described in the embodiments described later as one aspect, and do not limit the disclosed technical scope.

One disclosure related to a mobile terminal distance estimation system for achieving the above purpose is as follows:
an on-vehicle communication device (12) that is mounted on a vehicle (Hv) and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
a mobile terminal (2) that is carried by a user, receives a response request signal through ultra-wideband communication, and transmits a response signal, which is an impulse signal, to an in-vehicle communication device when the response request signal is received;
A distance estimation unit (F5) that estimates the distance between the in-vehicle communication device and the mobile terminal based on the round-trip time (Tp) from when the in-vehicle communication device transmits the response request signal to when it receives the response signal. ) A mobile terminal distance estimation system comprising:
The mobile terminal determines the time when the reception strength of the response request signal exceeds the detection threshold as the time when the response request signal is received,
The in-vehicle communication device determines the time when the reception strength of the response signal exceeds the detection threshold as the time when the response signal is received.
In-vehicle communication devices and mobile terminals have variable frequency bands for ultra-wideband communication.
The in-vehicle communication device and the mobile terminal determine that the wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimating unit is equal to or less than the high frequency possible distance,
When it is determined that the wideband conditions are met, the in-vehicle communication device and mobile terminal transmit impulses with a shorter time width and a steeper rise in the waveform by making the communication frequency wider than when the wideband conditions are not met. send and receive signals ,
The mobile terminal and in-vehicle communication device determine the broadband frequency band based on the country where the mobile terminal and in-vehicle communication device are located,
comprising an input device (27) for a user to input a country;
The mobile terminal and the in-vehicle communication device determine the country based on information input from the input device .
One disclosure related to a mobile terminal distance estimation system for achieving the above purpose is as follows:
an on-vehicle communication device (12) that is mounted on a vehicle (Hv) and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
a mobile terminal (2) that is carried by a user, receives a response request signal through ultra-wideband communication, and transmits a response signal, which is an impulse signal, to an in-vehicle communication device when the response request signal is received;
A distance estimation unit (F5) that estimates the distance between the in-vehicle communication device and the mobile terminal based on the round-trip time (Tp) from when the in-vehicle communication device transmits the response request signal to when it receives the response signal. ) A mobile terminal distance estimation system comprising:
The mobile terminal determines the time when the reception strength of the response request signal exceeds the detection threshold as the time when the response request signal is received,
The in-vehicle communication device determines the time when the reception strength of the response signal exceeds the detection threshold as the time when the response signal is received.
In-vehicle communication devices and mobile terminals have variable frequency bands for ultra-wideband communication.
The in-vehicle communication device and the mobile terminal determine that the wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimating unit is equal to or less than the high frequency possible distance,
When it is determined that the wideband conditions are met, the in-vehicle communication device and mobile terminal transmit impulses with a shorter time width and a steeper rise in the waveform by making the communication frequency wider than when the wideband conditions are not met. send and receive signals,
The mobile terminal and in-vehicle communication device determine the broadband frequency band based on the country where the mobile terminal and in-vehicle communication device are located,
Equipped with a position detection unit (29) that detects the position of the mobile terminal or in-vehicle communication device,
The mobile terminal and the in-vehicle communication device determine the country based on the position detected by the position detection unit.
One disclosure related to a mobile terminal distance estimation system for achieving the above purpose is as follows:
an on-vehicle communication device (12) that is mounted on a vehicle (Hv) and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
a mobile terminal (2) that is carried by a user, receives a response request signal through ultra-wideband communication, and transmits a response signal, which is an impulse signal, to an in-vehicle communication device when the response request signal is received;
A distance estimation unit (F5) that estimates the distance between the in-vehicle communication device and the mobile terminal based on the round-trip time (Tp) from when the in-vehicle communication device transmits the response request signal to when it receives the response signal. ) A mobile terminal distance estimation system comprising:
The mobile terminal determines the time when the reception strength of the response request signal exceeds the detection threshold as the time when the response request signal is received,
The in-vehicle communication device determines the time when the reception strength of the response signal exceeds the detection threshold as the time when the response signal is received.
In-vehicle communication devices and mobile terminals have variable frequency bands for ultra-wideband communication.
The in-vehicle communication device and the mobile terminal determine that the wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimating unit is equal to or less than the high frequency possible distance,
When it is determined that the wideband conditions are met, the in-vehicle communication device and mobile terminal transmit impulses with a shorter time width and a steeper rise in the waveform by making the communication frequency wider than when the wideband conditions are not met. send and receive signals,
When in-vehicle communication devices and mobile terminals widen the communication frequency, they shift the frequency band to a higher frequency band to widen the frequency band.
The distance estimator periodically estimates the distance,
The distance used to determine whether the broadbanding condition is satisfied is the latest distance estimated by the distance estimator.
One disclosure related to a mobile terminal distance estimation system for achieving the above purpose is as follows:
an on-vehicle communication device (12) that is mounted on a vehicle (Hv) and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
a mobile terminal (2) that is carried by a user, receives a response request signal through ultra-wideband communication, and transmits a response signal, which is an impulse signal, to an in-vehicle communication device when the response request signal is received;
A distance estimation unit (F5) that estimates the distance between the in-vehicle communication device and the mobile terminal based on the round-trip time (Tp) from when the in-vehicle communication device transmits the response request signal to when it receives the response signal. ) A mobile terminal distance estimation system comprising:
The mobile terminal determines the time when the reception strength of the response request signal exceeds the detection threshold as the time when the response request signal is received,
The in-vehicle communication device determines the time when the reception strength of the response signal exceeds the detection threshold as the time when the response signal is received.
In-vehicle communication devices and mobile terminals have variable frequency bands for ultra-wideband communication.
The in-vehicle communication device and the mobile terminal determine that the wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimating unit is equal to or less than the high frequency possible distance,
When it is determined that the wideband conditions are met, the in-vehicle communication device and mobile terminal transmit impulses with a shorter time width and a steeper rise in the waveform by making the communication frequency wider than when the wideband conditions are not met. send and receive signals,
When in-vehicle communication devices and mobile terminals widen the communication frequency, they shift the frequency band to a higher frequency band to widen the frequency band.
The distance estimator is a first distance estimator,
comprising a second distance estimation unit that estimates the distance between the mobile terminal and the in-vehicle communication device by a means different from the round trip time;
The distance used to determine whether the broadbanding condition is satisfied is the distance estimated by the second distance estimator.
One disclosure related to a mobile terminal distance estimation system for achieving the above purpose is as follows:
an on-vehicle communication device (12) that is mounted on a vehicle (Hv) and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
a mobile terminal (2) that is carried by a user, receives a response request signal through ultra-wideband communication, and transmits a response signal, which is an impulse signal, to an in-vehicle communication device when the response request signal is received;
A distance estimation unit (F5) that estimates the distance between the in-vehicle communication device and the mobile terminal based on the round-trip time (Tp) from when the in-vehicle communication device transmits the response request signal to when it receives the response signal. ) A mobile terminal distance estimation system comprising:
The mobile terminal determines the time when the reception strength of the response request signal exceeds the detection threshold as the time when the response request signal is received,
The in-vehicle communication device determines the time when the reception strength of the response signal exceeds the detection threshold as the time when the response signal is received.
In-vehicle communication devices and mobile terminals have variable frequency bands for ultra-wideband communication.
The in-vehicle communication device and the mobile terminal determine that the wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimating unit is equal to or less than the high frequency possible distance,
When it is determined that the wideband conditions are met, the in-vehicle communication device and mobile terminal transmit impulses with a shorter time width and a steeper rise in the waveform by making the communication frequency wider than when the wideband conditions are not met. send and receive signals,
If the communication is for calculating the correction time (ΔT) for correcting the round trip time, it is assumed that the broadband conditions are satisfied,
The in-vehicle communication device continuously transmits response request signals with different time widths in a wideband frequency band and a frequency band that is relatively narrow compared to the wideband frequency band. ,
When the mobile terminal receives a response request signal in a wide frequency band and a narrow frequency band, the mobile terminal transmits a response signal, respectively.
A correction time calculation unit (F4) that calculates a difference between a round trip time calculated using a wide frequency band and a round trip time calculated using a narrow frequency band as a correction time,
When the round trip time is calculated in a narrow frequency band, the distance estimation unit estimates the distance to the mobile terminal based on the round trip time plus the correction time.

The steeper the rise of the waveform of the impulse signal, the shorter the time difference between the point in time when the impulse signal exceeds the detection threshold and the point in time at the peak of the received signal. However, in order to make the rise of the impulse signal steep, it is necessary to widen the frequency band used by the impulse signal. Therefore, by widening the communication frequency only when the wideband conditions are met, the rise of the waveform is made steeper. By doing so, it is possible to accurately estimate the distance to the mobile terminal while complying with laws and regulations.

An in-vehicle system for achieving the above object is an in-vehicle system that can be included in the mobile terminal distance estimation system. In other words, the in-vehicle system is
an on-vehicle communication device (12) that is mounted on the vehicle and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
The in-vehicle communication device and An in-vehicle system comprising a distance estimation unit (F5) that estimates a distance to a mobile terminal,
The in-vehicle communication device is
The time when the reception strength of the response signal exceeds the detection threshold is the time when the response signal is received,
The frequency band for ultra-wideband communication is variable,
The in-vehicle communication device determines that the wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimation unit is less than or equal to the high frequency possible distance,
If it is determined that the wideband condition is satisfied, the communication frequency is made wider than when the wideband condition is not satisfied, and an impulse signal with a shorter time width and a steeper rise of the waveform is transmitted .
The in-vehicle communication device determines the broadband frequency band based on the country where the in-vehicle communication device is located,
an input device for a user to input a country;
The in-vehicle communication device determines the country based on information input from the input device .
The in-vehicle system is
an on-vehicle communication device (12) that is mounted on the vehicle and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
The in-vehicle communication device and An in-vehicle system comprising a distance estimation unit (F5) that estimates a distance to a mobile terminal,
The in-vehicle communication device is
The time when the reception strength of the response signal exceeds the detection threshold is the time when the response signal is received,
The frequency band for ultra-wideband communication is variable,
The in-vehicle communication device determines that the wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimation unit is less than or equal to the high frequency possible distance,
If it is determined that the wideband condition is satisfied, the communication frequency is made wider than when the wideband condition is not satisfied, and an impulse signal with a shorter time width and a steeper rise of the waveform is transmitted.
The in-vehicle communication device determines the broadband frequency band based on the country where the in-vehicle communication device is located,
Equipped with a position detection unit that detects the position of a mobile terminal or in-vehicle communication device,
The in-vehicle communication device determines the country based on the position detected by the position detection unit.
The in-vehicle system is
an on-vehicle communication device (12) that is mounted on the vehicle and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
The in-vehicle communication device and An in-vehicle system comprising a distance estimation unit (F5) that estimates a distance to a mobile terminal,
The in-vehicle communication device is
The time when the reception strength of the response signal exceeds the detection threshold is the time when the response signal is received,
The frequency band for ultra-wideband communication is variable,
The in-vehicle communication device determines that the wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimation unit is less than or equal to the high frequency possible distance,
If it is determined that the wideband condition is satisfied, the communication frequency is made wider than when the wideband condition is not satisfied, and an impulse signal with a shorter time width and a steeper rise of the waveform is transmitted.
When in-vehicle communication equipment widens the communication frequency, it shifts the frequency band to a higher frequency band to widen the frequency band.
The distance estimator periodically estimates the distance,
The distance used to determine whether the broadbanding condition is satisfied is the latest distance estimated by the distance estimator.
The in-vehicle system is
an on-vehicle communication device (12) that is mounted on the vehicle and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
The in-vehicle communication device and An in-vehicle system comprising a distance estimation unit (F5) that estimates a distance to a mobile terminal,
The in-vehicle communication device is
The time when the reception strength of the response signal exceeds the detection threshold is the time when the response signal is received,
The frequency band for ultra-wideband communication is variable,
The in-vehicle communication device determines that the wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimation unit is less than or equal to the high frequency possible distance,
If it is determined that the wideband condition is satisfied, the communication frequency is made wider than when the wideband condition is not satisfied, and an impulse signal with a shorter time width and a steeper rise of the waveform is transmitted.
When in-vehicle communication equipment widens the communication frequency, it shifts the frequency band to a higher frequency band to widen the frequency band.
The distance estimator is a first distance estimator,
comprising a second distance estimation unit that estimates the distance between the mobile terminal and the in-vehicle communication device by a means different from the round trip time;
The distance used to determine whether the broadbanding condition is satisfied is the distance estimated by the second distance estimator.
The in-vehicle system is
an on-vehicle communication device (12) that is mounted on the vehicle and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
The in-vehicle communication device and An in-vehicle system comprising a distance estimation unit (F5) that estimates a distance to a mobile terminal,
The in-vehicle communication device is
The time when the reception strength of the response signal exceeds the detection threshold is the time when the response signal is received,
The frequency band for ultra-wideband communication is variable,
The in-vehicle communication device determines that the wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimation unit is less than or equal to the high frequency possible distance,
If it is determined that the wideband condition is satisfied, the communication frequency is made wider than when the wideband condition is not satisfied, and an impulse signal with a shorter time width and a steeper rise of the waveform is transmitted.
If the communication is for calculating the correction time (ΔT) for correcting the round trip time, it is assumed that the broadband conditions are satisfied,
The in-vehicle communication device continuously transmits response request signals with different time widths in a wideband frequency band and a frequency band that is relatively narrow compared to the wideband frequency band. ,
The in-vehicle communication device receives a response signal transmitted from the mobile terminal when the mobile terminal receives a response request signal in a wide frequency band and a narrow frequency band, respectively,
A correction time calculation unit (F4) that calculates a difference between a round trip time calculated using a wide frequency band and a round trip time calculated using a narrow frequency band as a correction time,
When the round trip time is calculated in a narrow frequency band, the distance estimation unit estimates the distance to the mobile terminal based on the round trip time plus the correction time.

FIG. 1 is a diagram showing the overall configuration of a digital key system. 2 is a block diagram showing a part of the internal configuration of the smartphone 2. FIG. 1 is a block diagram illustrating the configuration of an in-vehicle system 1. FIG. FIG. 3 is a diagram illustrating an example of the mounting position of the UWB communication device 12. FIG. 1 is a block diagram showing the configuration of a smart ECU 11 and a UWB communication device 12. FIG. 3 is a block diagram showing the configuration of a transmitting circuit 311 included in the UWB communication device 12. FIG. 3 is a block diagram showing the configuration of a receiving circuit 322 included in the UWB communication device 12. FIG. It is a figure explaining round trip time Tp. 2 is a diagram showing transmission and reception of impulse signals from the vehicle Hv to the smartphone 2. FIG. It is a diagram showing transmission and reception of impulse signals from the smartphone 2 to the vehicle Hv. It is a flowchart which shows the process which smart ECU11 performs in a position estimation process.

Hereinafter, the mobile terminal distance estimating system of the present disclosure will be explained using figures. In the following embodiments, a digital key system having the functions of a mobile terminal distance estimation system will be described. As shown in FIG. 1, the digital key system of the embodiment includes an in-vehicle system 1 mounted on a vehicle Hv, and a smartphone 2 that is a mobile terminal carried by a user of the vehicle Hv.

[Overview]
The smartphone 2 functions as a digital key for the in-vehicle system 1. In order for the smartphone 2 to function as a digital key, it is necessary to transmit digital key information authenticated by the in-vehicle system 1 to the in-vehicle system 1. The smartphone 2 acquires and stores digital key information in advance from a server or the like.

The digital key information has an expiration date, and within the expiration date, the in-vehicle system 1 allows the smartphone 2 to operate the in-vehicle device. However, the condition for the in-vehicle system 1 to permit the smartphone 2 to operate the in-vehicle device is not only that the digital key information can be authenticated. The position or distance of the smartphone 2 with respect to the vehicle Hv is also a condition. Therefore, the in-vehicle system 1 determines the distance or position of the smartphone 2.

In order for the in-vehicle system 1 to determine the distance or position of the smartphone 2, radio waves between the in-vehicle system 1 and the smartphone 2 are used. Specifically, the propagation time of radio waves is used. In order to accurately measure the propagation time, the in-vehicle system 1 and the smartphone 2 are configured to be able to perform UWB-IR (Ultra Wide Band - Impulse Radio) wireless communication (hereinafter referred to as UWB communication). That is, the in-vehicle system 1 and the smartphone 2 are configured to be able to transmit and receive impulse-like radio waves (hereinafter referred to as impulse signals) used in UWB communication. The impulse signal used in UWB communication is a signal that has an extremely short pulse width (for example, 2 nanoseconds) and a bandwidth of about 500 MHz or more (that is, ultra-wide bandwidth). Note that UWB communication is sometimes called ultra-wideband communication.

Frequency bands that can be used for UWB communication (hereinafter referred to as UWB bands) are determined by laws and regulations. For example, 3.2 GHz to 10.6 GHz, 3.4 GHz to 4.8 GHz, 7.25 GHz to 10.6 GHz, 22 GHz to 29 GHz, etc. are specified.

In Japan, two types of UWB bands are specified. Of these two types of UWB bands, the relatively lower UWB band (hereinafter referred to as low UWB band) is 3.4 to 4.8 GHz. The higher UWB band (hereinafter referred to as high UWB band) is 7.25 to 10.25 GHz. The bandwidth of the low UWB band, which is a low frequency band, is 1.4 GHz, whereas the bandwidth of the high UWB band, which is a high frequency band, is 3 GHz, and the high UWB band is wider. The frequency band used for the impulse signal may be appropriately selected depending on the country in which the vehicle Hv is used. The impulse signal in this embodiment is transmitted and received using the above two types of frequency bands that can be used in Japan.

Various modulation methods can be used for UWB-IR communication, such as a PPM (pulse position modulation) method that performs modulation at the pulse generation position. Specifically, On Off Keying (OOK), Pulse Width Modulation (PWM), Pulse-Amplitude Modulation (PAM), and Pulse-Code Modulation (PCM) are used. Modulation) etc. can be adopted. Note that the on-off modulation method is a method for expressing information (for example, 0 and 1) by the presence/absence of an impulse signal, and the pulse width modulation method is a method for expressing information by the pulse width. The pulse amplitude modulation method is a method for expressing information by the amplitude of an impulse signal. The pulse code modulation method is a method that expresses information by a combination of pulses.

In addition, the in-vehicle system 1 and the smartphone 2 of this embodiment are configured to be able to perform wireless communication (hereinafter referred to as BLE communication) based on the Bluetooth Low Energy (Bluetooth is a registered trademark) standard as a second communication method. . Note that the first communication method refers to the above-mentioned UWB communication. In addition to Bluetooth Low Energy, the second communication method employs various short-range wireless communication methods such as Wi-Fi (registered trademark) and ZigBee (registered trademark), which can set the communication distance to about 10 meters. It is possible. The second communication method may be one that can provide a communication distance of, for example, several meters to several tens of meters. Hereinafter, in order to distinguish between a UWB communication signal and a BLE communication signal, a wireless signal compliant with the BLE standard will also be referred to as a BLE signal. Hereinafter, the specific configurations of the in-vehicle system 1 and the smartphone 2 will be explained in order.

[Configuration of smartphone 2]
First, the configuration and operation of the smartphone 2 will be explained. As shown in FIG. 2, the smartphone 2 includes a UWB communication section 21, a BLE communication section 22, a wide area communication section 23, a GNSS receiver 24, a terminal storage section 25, a notification section 26, an input device 27, and a terminal side control section 28. Be prepared. The terminal side control unit 28 is connected to each of the UWB communication unit 21, the BLE communication unit 22, the wide area communication unit 23, the GNSS receiver 24, the terminal storage unit 25, the notification unit 26, and the input device 27 so as to be able to communicate with each other. .

The UWB communication unit 21 is a communication module for transmitting and receiving UWB impulse signals. The UWB communication unit 21 transmits an impulse signal matching the baseband signal input from the terminal side control unit 28 by UWB communication. The configuration of the UWB communication unit 21 is the same as that of the UWB communication device 12 described later. Further, upon receiving a pulse sequence signal made up of a plurality of impulse signals transmitted from the in-vehicle system 1, the UWB communication unit 21 restores a baseband signal from the received signal. Then, the baseband signal is output to the terminal side control section 28.

The BLE communication unit 22 is a communication module for implementing BLE communication. The BLE communication unit 22 receives the BLE signal transmitted from the vehicle Hv and provides it to the terminal-side control unit 28, and also modulates data input from the terminal-side control unit 28 and transmits the modulated data to the vehicle Hv.

The wide area communication unit 23 is a communication unit capable of wide area communication using a public communication network. The wide area communication section 23 can communicate with the wide area communication section 31. The GNSS receiver 24 receives navigation signals transmitted by navigation satellites included in GNSS (Global Navigation Satellite System), which is a satellite navigation system, and sequentially calculates the current position based on the received navigation signals. The terminal storage unit 25 is a writable nonvolatile memory. The terminal storage unit 25 stores digital key information transmitted from the server. The notification section 26 is one or both of a display section and a speaker. The notification unit 26 outputs various notifications. The input device 27 is a touch panel superimposed on the display surface of the display unit.

The terminal side control unit 28 is realized using a computer including, for example, a CPU, a RAM, a ROM, and the like. When receiving data indicating a response request signal is input from the UWB communication unit 21, the terminal side control unit 28 generates a baseband signal corresponding to a response signal in response to the response request signal, and transmits this baseband signal to the UWB communication. It is output to section 21. The baseband signal outputted by the terminal-side control unit 28 to the UWB communication unit 21 is modulated by the UWB communication unit 21 and transmitted as a response radio wave.

The terminal side control section 28 includes a position detection section 29 . The position detection unit 29 detects the current position of the smartphone 2 by acquiring the current position from the GNSS receiver 24.

[In-vehicle system 1]
The in-vehicle system 1 is a passive entry passive start system (hereinafter referred to as "passive entry passive start system") that performs predetermined vehicle control according to the location of the smartphone 2 by performing wireless communication with the smartphone 2 using radio waves in a predetermined frequency band. PEPS system).

For example, if the in-vehicle system 1 is able to confirm that the smartphone 2 is present within an operating area preset for the vehicle Hv, the in-vehicle system 1 locks the door based on the user's operation on the door button 14, which will be described later. Executes controls such as locking and unlocking. In addition, if the in-vehicle system 1 can confirm that the smartphone 2 is present in the vehicle interior through wireless communication with the smartphone 2, the in-vehicle system 1 executes engine starting control based on the user's operation on the start button 15, which will be described later. do.

The operation area is an area where the in-vehicle system 1 executes predetermined vehicle control such as locking and unlocking the doors based on the presence of the smartphone 2 in the area. For example, the activation area is set near the driver's seat door, the passenger seat door, and the trunk door. The vicinity of the door refers to an area within a predetermined operating distance from the outside door handle. The outer door handle refers to a gripping member provided on the outer surface of the door for opening and closing the door. The working distance that defines the size of the working area is, for example, 0.7 m. Of course, the working distance may be 1 m or 1.5 m. The working distance is often set smaller than 2 m from the viewpoint of crime prevention.

As shown in FIG. 3, the in-vehicle system 1 includes a smart ECU 11, a plurality of UWB communication devices 12, a BLE communication device 13, a door button 14, a start button 15, an engine ECU 16, a body ECU 17, and a wide area communication device 19. The on-vehicle system 1 also includes an on-vehicle actuator 171, an on-vehicle sensor 172, and the like. Note that ECU in the component names is an abbreviation for Electronic Control Unit and means an electronic control device.

The smart ECU 11 is an ECU that performs vehicle control such as locking and unlocking doors and starting the engine by performing UWB communication with the smartphone 2. The smart ECU 11 is connected to an engine ECU 16 and a body ECU 17 so as to be able to communicate with each other via a communication network built within the vehicle. The smart ECU 11 is also electrically connected to the UWB communication device 12, the BLE communication device 13, the door button 14, and the start button 15. The smart ECU 11 is realized using a computer, for example. That is, the smart ECU 11 includes a CPU 111, a flash memory 112, a RAM 113, an I/O 114, and a bus line connecting these components.

The flash memory 112 stores a program (hereinafter referred to as a position estimation program) for making the computer function as the smart ECU 11, and the like. Note that the above-described position estimation program may be stored in a non-transitive tangible storage medium. Executing the position estimation program by the CPU 111 corresponds to executing a method corresponding to the position estimation program. Details of the smart ECU 11 will be described separately later.

The UWB communication device 12 is a communication module for performing UWB communication with the smartphone 2. The UWB communication device 12 is an in-vehicle communication device provided for estimating the location of the smartphone 2. Each UWB communication device 12 is connected to the smart ECU 11 via a dedicated communication line or an in-vehicle network so as to be able to communicate with each other. The operation of each UWB communication device 12 is controlled by the smart ECU 11. Each UWB communication device 12 is assigned a unique communication device number. The communication device number is information equivalent to a terminal ID for the smartphone 2. The communication device number functions as information for identifying the plurality of UWB communication devices 12. The mounting positions and electrical configurations of the plurality of UWB communication devices 12 will be described separately later.

The BLE communication device 13 is a communication module for implementing BLE communication. The BLE communication device 13 is connected to the smart ECU 11 so as to be able to communicate with each other. The BLE communication device 13 receives the BLE signal transmitted from the smartphone 2 and provides it to the smart ECU 11. Further, the BLE communication device 13 modulates data input from the smart ECU 11 and wirelessly transmits the modulated data to the smartphone 2. The BLE communication device 13 is attached to an arbitrary position of the vehicle Hv. For example, the BLE communication device 13 is attached to an instrument panel, the upper end of a windshield, a B-pillar, a rocker, or the like. There may be one BLE communication device 13, or there may be a plurality of BLE communication devices 13.

The door button 14 is a button used by the user to unlock and lock the door of the vehicle Hv. The door button 14 is provided, for example, on each door handle of the vehicle Hv. When the door button 14 is pressed by the user, it outputs an electrical signal indicating this to the smart ECU 11. The door button 14 corresponds to a configuration for the smart ECU 11 to receive unlocking instructions and locking instructions from the user. Note that a touch sensor may be employed as the configuration for receiving at least one of the user's unlocking instruction and locking instruction. A touch sensor is a device that detects when a user is touching the door handle.

The start button 15 is a push switch that allows the user to start the drive source (for example, the engine) of the vehicle Hv. When the start button 15 is pushed by the user, it outputs an electric signal to the smart ECU 11 to indicate the push operation. Here, as an example, the vehicle Hv is a vehicle equipped with an engine as a power source, but the present invention is not limited to this. Vehicle Hv may be an electric vehicle or a hybrid vehicle. When the vehicle Hv is a vehicle equipped with a motor as a drive source, the start button 15 is a switch for starting the drive motor.

The engine ECU 16 is an ECU that controls the operation of the engine mounted on the vehicle Hv. For example, when the engine ECU 16 receives a start instruction signal instructing to start the engine from the smart ECU 11, the engine ECU 16 starts the engine.

The body ECU 17 is an ECU that controls the on-vehicle actuator 171 based on requests from the smart ECU 11. The body ECU 17 is communicably connected to various on-vehicle actuators 171 and various on-vehicle sensors 172. The in-vehicle actuator 171 here is, for example, a door lock motor that constitutes a lock mechanism for each door, a seat actuator for adjusting the seat position, or the like. Furthermore, the on-vehicle sensor 172 here is a courtesy switch or the like arranged in each door. A courtesy switch is a sensor that detects opening and closing of a door. The body ECU 17 locks and unlocks each door by outputting a predetermined control signal to a door lock motor provided on each door of the vehicle Hv based on a request from the smart ECU 11, for example.

[About the installation position and electrical configuration of each UWB communication device 12]
The in-vehicle system 1 of this embodiment includes, as the UWB communication device 12, a right front communication device 12A, a left front communication device 12B, a right rear communication device 12C, and a left rear communication device 12D, as shown in FIG. The right front communication device 12A is arranged, for example, in the upper region of the A-pillar on the right side of the vehicle. The A-pillar is the first pillar from the front in the vehicle Hv. The A-pillar is also called the front pillar. The upper region of the pillar refers to the region that is the upper half of the pillar. The upper region of the pillar also includes the upper end of the pillar. The left front communication device 12B is arranged, for example, in the upper region of the A-pillar on the left side of the vehicle. The right rear communication device 12C is arranged in the upper region of the C-pillar on the right side of the vehicle. The left rear communication device 12D is arranged in the upper area of the C-pillar on the left side of the vehicle. The C-pillar is the third pillar from the front. The C-pillar is also called the rear pillar.

In the configuration in which the distance is measured using the propagation time of radio waves as in this embodiment, each UWB communication device 12 is preferably placed in a position with good visibility to both the interior of the vehicle and the exterior of the vehicle. preferable. Places with good visibility both inside and outside the vehicle include, for example, the interior ceiling and various pillars. In other words, as described above, the manner in which the various UWB communication devices 12 are arranged corresponds to an example of a manner in which each UWB communication device 12 is placed at a position where it is easy to see inside and outside the vehicle.

The installation position of each UWB communication device 12 in the vehicle Hv may be expressed as a point in a three-dimensional orthogonal coordinate system with an arbitrary point on the vehicle as the reference point (in other words, the origin). Here, as an example, points are expressed as points on a three-dimensional coordinate system (hereinafter referred to as vehicle three-dimensional coordinate system) having the center of the front wheel axle as the origin and having X, Y, and Z axes orthogonal to each other. The X-axis forming the vehicle three-dimensional coordinate system is parallel to the vehicle width direction, and is an axis whose positive direction is on the right side of the vehicle. The Y-axis is parallel to the longitudinal direction of the vehicle, and the forward direction of the vehicle is an axis. The Z-axis is an axis that is parallel to the vehicle height direction and whose positive direction is above the vehicle. The center of the three-dimensional coordinate system can be changed as appropriate, such as the center of the rear wheel axle, for example. Of course, as another aspect, the mounting position of each UWB communication device 12 may be expressed in polar coordinates. Communication device position data indicating the installation position of each UWB communication device 12 is stored in the flash memory 112. The installation position of each UWB communication device 12 may be stored in association with the communication device number.

Each of the plurality of UWB communication devices 12 includes a transmitting section 310, a receiving section 320, and a round trip time measuring section 330, as shown in FIG. The transmitting section 310 includes a transmitting circuit 311 and a transmitting antenna 312. FIG. 6 shows a specific configuration of the transmitting circuit 311. The transmission circuit 311 includes an impulse generator 313, a variable bandpass filter 314, and an amplifier 315. Transmission data is input to the impulse generator 313 from the smart ECU 11 . Impulse generator 313 generates an impulse signal matching the input transmission data, and inputs the impulse signal to variable bandpass filter 314 .

The variable bandpass filter 314 has a variable pass frequency band. By including the variable bandpass filter 314, the UWB communication device 12 can vary the communication frequency. The pass frequency band is controlled by the smart ECU 11. The variable bandpass filter 314 can switch the pass frequency band between a low UWB band, ie, 3.4-4.8 GHz, and a high UWB band, ie, 7.25-10.25 GHz. Amplifier 315 amplifies the impulse signal that has passed through variable bandpass filter 314 and outputs it to transmitting antenna 312 . The amplification factor of the amplifier 315 is constant and set so that the antenna power complies with the Radio Law.

The explanation returns to FIG. 5. The receiving section 320 includes a receiving antenna 321 and a receiving circuit 322. FIG. 7 shows a specific configuration of the receiving circuit 322. The receiving circuit 322 includes an amplifier 323 and a detector 324. Amplifier 323 amplifies the received signal received by receiving antenna 321. The detector 324 extracts an impulse signal, which is received data, from the received signal amplified by the amplifier 323. The detector 324 extracts the impulse signal by, for example, envelope detection. The detector 324 outputs the extracted impulse signal to the smart ECU 11.

The round trip time measuring section 330 is a timer that measures the elapsed time (hereinafter referred to as round trip time Tp) from when the transmitting section 310 transmits the impulse signal until the receiving section 320 receives the impulse signal. The timing at which the transmitter 310 transmits the impulse signal is specified by the input of the transmission notification signal. Further, the timing at which the receiving unit 320 receives the impulse signal is specified by inputting the reception notification signal. That is, the round trip time measuring section 330 measures the time from when the transmitting circuit 311 outputs the transmission notification signal until when the receiving circuit 322 outputs the reception notification signal. As shown in FIG. 8, the round trip time Tp corresponds to the sum of the round trip propagation time Ta and the internal processing time Tb in the smartphone 2.

The round trip time measuring section 330 measures the elapsed time since the transmitting section 310 transmits the impulse signal by counting clock signals input from a clock oscillator (not shown). Counting by the round trip time measuring section 330 is stopped when a reception notification signal is input or when a predetermined upper limit is reached, and the count value is output to the smart ECU 11. That is, the round trip time Tp is reported to the smart ECU 11. Note that when the reporting of the round trip time Tp to the smart ECU 11 is completed, the count value of the round trip time measuring section 330 returns to 0 (that is, it is reset).

When the measurement of the round trip time Tp is completed, the round trip time measurement unit 330 provides the round trip time Tp to the smart ECU 11. The round trip time measuring section 330 is realized using, for example, an IC. Note that although the UWB communication device 12 is shown here as having a transmitting antenna (that is, the transmitting antenna 312) and a receiving antenna (that is, the receiving antenna 321) separately provided, the present invention is not limited to this. do not have. The UWB communication device 12 may be configured to share one antenna element for transmission and reception using a directional coupler. Furthermore, the transmitting circuit 311 and the receiving circuit 322 may be built into an IC that provides the function of the round trip time measuring section 330. That is, the UWB communication device 12 may be realized using one antenna and one dedicated IC having various circuit functions.

[About the functions of smart ECU11]
The smart ECU 11 provides functions corresponding to the various functional blocks shown in FIG. 7 by executing the position estimation program described above. That is, the smart ECU 11 includes a vehicle information acquisition section F1, a communication processing section F2, an authentication processing section F3, a correction time calculation section F4, a distance estimation section F5, a position estimation section F6, and a vehicle control section F7 as functional blocks.

The vehicle information acquisition unit F1 acquires various information (hereinafter referred to as vehicle information) indicating the state of the vehicle Hv from sensors, ECUs (for example, body ECU 17), switches, etc. mounted on the vehicle Hv. The vehicle information includes, for example, the open/closed state of the doors, the locked/unlocked state of each door, whether the door button 14 is pressed or not, and whether the start button 15 is pressed or not. Furthermore, the vehicle information acquisition unit F1 identifies the current state of the vehicle Hv based on the various information mentioned above. For example, the vehicle information acquisition unit F1 determines that the vehicle Hv is parked when the engine is off and all doors are locked. Of course, the conditions for determining that the vehicle Hv is parked may be designed as appropriate, and various determination conditions may be applied.

Note that acquiring information indicating the locked/unlocked status of each door corresponds to determining the locked/unlocked status of each door and detecting the locking/unlocking operation of the door by the user. do. Furthermore, acquiring electrical signals from the door button 14 and the start button 15 corresponds to detecting user operations on these buttons. In other words, the vehicle information acquisition unit F1 corresponds to a configuration that detects user operations on the vehicle Hv, such as opening and closing a door, pressing the door button 14, pressing the start button 15, and the like. The vehicle information hereinafter also includes user operations on the vehicle Hv. In addition, the types of information included in the vehicle information are not limited to those described above. The vehicle information also includes a shift position detected by a shift position sensor (not shown) and a detection result of a brake sensor that detects whether the brake pedal is depressed. The operating state of the parking brake can also be included in the vehicle information.

The communication processing unit F2 is configured to transmit and receive data to and from the smartphone 2 in cooperation with the UWB communication device 12 and the BLE communication device 13. For example, the communication processing unit F2 generates data addressed to the smartphone 2 and outputs it to the BLE communication device 13. This causes a signal corresponding to the desired data to be transmitted as radio waves. Further, the communication processing unit F2 receives data from the smartphone 2 that the BLE communication device 13 receives. In this embodiment, as a more preferable aspect, wireless communication between the smart ECU 11 and the smartphone 2 is configured to be encrypted. As the encryption method, various methods can be used, such as the method specified by Bluetooth.

In this embodiment, in order to improve security, the smart ECU 11 and the smartphone 2 are configured to encrypt data communication for authentication and the like, but the invention is not limited to this. As another aspect, the smart ECU 11 and the smartphone 2 may be configured to perform data communication without encryption.

The communication processing unit F2 recognizes that the user is present around the vehicle Hv based on the fact that BLE communication with the smartphone 2 is established. The communication processing unit F2 also acquires, from the BLE communication device 13, the terminal ID of the smartphone 2 to which the BLE communication device 13 is connected for communication. According to such a configuration, even if the vehicle Hv is a vehicle that is shared by multiple users, the smart ECU 11 can control the surroundings of the vehicle Hv based on the terminal ID of the smartphone 2 to which the BLE communication device 13 is communicatively connected. Existing users can be identified.

Furthermore, the communication processing unit F2 acquires data from the smartphone 2 that the UWB communication device 12 receives. In addition, the communication processing unit F2 generates data addressed to the smartphone 2 and outputs it to the UWB communication device 12. As a result, a pulse sequence signal corresponding to desired data is wirelessly transmitted. Further, the communication processing unit F2 causes any UWB communication device 12 to transmit an impulse signal based on an instruction from the position estimation unit F6.

The communication processing unit F2 determines whether the UWB communication device 12 is to operate in the normal mode or the high frequency mode, and instructs the UWB communication device 12 in the determined mode. Further, the UWB communication device 12 or the BLE communication device 13 also transmits a signal to the smartphone 2 instructing whether to operate the UWB communication unit 21 in the normal mode or in the high frequency mode. The distance estimation unit F5 determines whether to use the normal mode or the high frequency mode. The contents of the normal mode and high frequency mode will be explained in the correction time calculation section F4.

The communication processing unit F2 determines the frequency bands used in the normal mode and high frequency mode. The communication processing unit F2 determines the frequency band to be used in the normal mode and the high frequency mode based on the area where the in-vehicle system 1 and the smartphone 2 are located. Region refers to the region that establishes laws and regulations regarding radio waves, and in many cases is a country. However, there are cases where the region that sets the radio wave regulations is larger than the country, and there are also cases where multiple countries form a single region regarding the radio wave regulations.

In this embodiment, the communication processing unit F2 acquires the current location through communication with the smartphone 2 in order to determine this area. Since the smartphone 2 includes the position detection section 29, it can detect the current position. The smartphone 2 transmits the current position detected by the position detection unit 29 to the in-vehicle system 1. Thereby, the communication processing unit F2 can acquire the current position. Note that the in-vehicle system 1 can also include the position detection section 29. The communication processing unit F2 determines the area based on the acquired current location. If the area is Japan, the low UWB band is used in the normal mode, and the high UWB band is used in the high frequency mode. Note that instead of determining the region based on the current location, the user directly inputs the region from the input device 27 included in the smartphone 2, and the communication processing unit F2 inputs the region via wireless communication. It is also possible to obtain the specified area.

With a similar configuration, the smartphone 2 can also determine the frequency bands to be used in the normal mode and high frequency mode. Further, the in-vehicle system 1 may notify the smartphone 2 of the frequency bands used in the normal mode and the high frequency mode. Conversely, the smartphone 2 may notify the in-vehicle system 1 of the frequency bands used in the normal mode and the high frequency mode.

The authentication processing unit F3 cooperates with the BLE communication device 13 to perform a process of confirming (in other words, authenticating) that the communication partner is the user's smartphone 2. Communication for authentication is encrypted and carried out via the BLE communication device 13. In other words, the authentication process is performed using encrypted communication. The authentication process itself may be performed using various methods such as a challenge-response method. A detailed explanation thereof will be omitted here. The timing at which the authentication processing unit F3 performs the authentication process may be, for example, the timing at which the communication connection between the BLE communication device 13 and the smartphone 2 is established. The authentication processing unit F3 may be configured to perform authentication processing at a predetermined cycle while the BLE communication device 13 and the smartphone 2 are communicatively connected. Furthermore, the encrypted communication for authentication processing may be performed using a predetermined user operation on the vehicle Hv as a trigger, such as when the start button 15 is pressed by the user.

By the way, in the Bluetooth standard, the establishment of a communication connection between the BLE communication device 13 and the smartphone 2 means that the communication partner of the BLE communication device 13 is the smartphone 2 registered in advance. Therefore, the smart ECU 11 may be configured to determine that the authentication of the smartphone 2 has been successful based on the establishment of the communication connection between the BLE communication device 13 and the smartphone 2.

The correction time calculation unit F4 calculates a correction time ΔT for correcting the round trip time Tp in the normal mode. The normal mode is one of the modes in which the distance to the smartphone 2 is estimated based on the round trip time Tp. Modes for estimating the distance to the smartphone 2 include a high frequency mode in addition to the normal mode.

The UBW communication of this embodiment can use a low UWB band and a high UWB band. Normally, a low UWB band is used. Therefore, the normal mode is a mode that uses the low UWB band. On the other hand, the high frequency mode is a mode that uses a high UWB band. If the transmission power is the same, the lower the frequency, the longer the communication distance. Since the communication distance of UWB communication is not very long, the low UWB band, which has a long communication distance, is normally used.

In the normal mode, impulse signals in frequency bands covering the entire low UWB band are transmitted and received. In the high frequency mode, impulse signals in a frequency band covering the entire high UWB band are transmitted and received. As mentioned above, the bandwidth of the low UWB band is 1.4 GHz, while the bandwidth of the high UWB band is 3 GHz. Therefore, it can be said that the high frequency mode is a mode that uses a frequency band wider than that of the normal mode. In other words, the normal mode can be said to be a mode that uses a frequency band narrower than the high frequency mode.

Next, the reason for calculating the correction time ΔT will be explained. Both the UWB communication device 12 included in the in-vehicle system 1 and the UWB communication unit 21 included in the smartphone 2 define the time when the signal strength of the received radio waves exceeds the detection threshold TH as the signal reception time. Therefore, the reception time of the impulse signal is different from the time when the reception strength of the impulse signal reaches its peak. As mentioned above, a 1 nanosecond shift in propagation time can shift the estimated distance by 30 centimeters. Therefore, in order to accurately estimate the distance, it is preferable that the reception time of the impulse signal be close to the time when the reception strength of the impulse signal reaches its peak.

Incidentally, the broader the impulse signal, the narrower the impulse signal in the time domain. Therefore, the wider the impulse signal, the closer the reception time of the impulse signal and the time when the reception intensity of the impulse signal reaches its peak.

Therefore, the reception time of the impulse signal detected in the widened frequency band, that is, the high UWB band, is regarded as the time without error. The time difference between this reception time and the reception time of an impulse signal detected in a narrow frequency band, that is, a low UWB band is a time error that leads to a distance error in the normal mode.

FIG. 9 shows various times when the UWB communication device 12 transmits an impulse signal and the UWB communication unit 21 receives the impulse signal. In addition, in FIG. 9, the UWB communication device 12 and the UWB communication unit 21 are replaced with a vehicle Hv and a smartphone 2, which are devices equipped with these, respectively. This is to make it easier to distinguish between the UWB communication device 12 and the UWB communication unit 21. Further, the broken line is an impulse signal in the normal mode, and the solid line is an impulse signal in the high frequency mode. As shown in FIG. 9, the waveform of the impulse signal in the high frequency mode has a steeper rise than that of the impulse signal in the normal mode. This is because the impulse signal in the high frequency mode has a wide signal frequency band, and therefore has a narrow time width in the time domain.

In FIG. 9, the UWB communication device 12 mounted on the vehicle Hv transmits an impulse signal, which is a response request signal, at time t0. The reception time at which the UWB communication unit 21 installed in the smartphone 2 determines that it has received this impulse signal is time t1 in the normal mode, and time t2 in the high frequency mode. The peak of the received signal occurs at time t3, which is after time t2.

In the normal mode, the propagation time for the impulse signal to propagate from the vehicle Hv to the smartphone 2 is calculated as T10. On the other hand, in the high frequency mode, the propagation time is calculated as T20. There is a time difference ΔTm between these two propagation times.

In FIG. 10, the smartphone 2 that has received the response request signal is transmitting an impulse signal that is a response signal. Note that in FIG. 10 as well, the UWB communication device 12 and the UWB communication unit 21 are replaced with a vehicle Hv and a smartphone 2. Further, the broken line is an impulse signal in the normal mode, and the solid line is an impulse signal in the high frequency mode.

In FIG. 10, the UWB communication unit 21 installed in the smartphone 2 transmits an impulse signal, which is a response signal, at time t4. Time t4 is the time when internal processing time Tb has elapsed since time t3. The reception time at which it is determined that the UWB communication device 12 mounted on the vehicle Hv has received this impulse signal is time t5 in the normal mode, and time t6 in the high frequency mode. The peak of the received signal occurs at time t7, which is after time t6.

In the normal mode, the propagation time for the impulse signal to propagate from the smartphone 2 to the vehicle Hv is calculated as T54. On the other hand, in the high frequency mode, the propagation time is calculated as T64. There is a time difference ΔTc between these two propagation times.

FIG. 9 is a conceptual diagram explaining the time difference ΔTm, and in reality, impulse signals are not transmitted simultaneously at time t0 in the two modes. Therefore, propagation times T10 and T20 cannot be calculated. Further, FIG. 10 is also a conceptual diagram for explaining the time difference ΔTc, and in reality, impulse signals are not transmitted at the same time at time t4 in the two modes. Therefore, propagation times T54 and T64 cannot be calculated.

Therefore, the difference between the round-trip time Tp calculated using a wide frequency band, that is, the high UWB band, and the round-trip time Tp calculated using the narrow frequency band, that is, the low UWB band, is defined as the correction time ΔT. calculate.

It is possible to sequentially calculate the round trip time Tp when using the high UWB band and the round trip time Tp when using the low UWB band. The round trip time Tp when using the high UWB band is T20+Tb+T64. The round trip time Tp when using the low UWB band is T10+Tb+T54. Therefore, the correction time ΔT can be expressed by Equation 1.
(Formula 1) ΔT=T20+Tb+T64-(T10+Tb+T54)
When formula 1 is calculated and rearranged, formula 2 is obtained.
(Formula 2) ΔT=(T20-T10)+(T64-T54)
=ΔTm+ΔTc
From Equation 2, the difference between the round trip time Tp calculated using the high UWB band and the round trip time Tp calculated using the low UWB band is when using the high UWB band and when using the low UWB band. It can be seen that this represents the detection time difference of the impulse signals. The correction time calculation unit F4 stores the calculated correction time ΔT in the flash memory 112.

The distance estimating unit F5 causes each UWB communication device 12 to transmit and receive impulse signals to and from the smartphone 2 in a predetermined order, and obtains the round trip time Tp from each UWB communication device 12 via the communication processing unit F2. Based on this round trip time Tp and internal processing time Tb, the distance from each UWB communication device 12 to the smartphone 2 is estimated. It is assumed that a standard value of the internal processing time Tb is stored in the flash memory 112 in advance.

Specifically, in the high frequency mode, the distance estimation unit F5 subtracts the internal processing time Tb from the round trip time Tp, and divides the subtracted value by 2. Thereby, the propagation time Ta can be calculated. That is, the propagation time Ta is calculated using Equation 3. Then, the distance to the smartphone 2 is calculated by multiplying this propagation time Ta by the speed of light.
(Formula 3) Ta=(Tp-Tb)/2
On the other hand, in the normal mode, the distance estimating unit F5 calculates the propagation time Ta using Equation 4 below.
(Formula 4) Ta=(Tp+ΔT-Tb)/2
The position estimation unit F6 estimates the position of the smartphone 2 based on the distance from each UWB communication device 12 to the smartphone 2 estimated by the distance estimation unit F5. The position estimation process for estimating the position of the smartphone 2, including the process executed by the position estimation unit F6, will be described separately later.

If the authentication processing unit F3 has successfully authenticated the smartphone 2, the vehicle control unit F7 cooperates with the body ECU 17 to perform vehicle control according to the position of the smartphone 2 (in other words, the user) and the state of the vehicle Hv. It is a configuration that works and executes. The state of the vehicle Hv is determined by the vehicle information acquisition unit F1. The position of the smartphone 2 is determined by the position estimation unit F6.

For example, in a situation where the vehicle Hv is parked, when the smartphone 2 exists outside the vehicle interior and the door button 14 is pressed by the user, the vehicle control unit F7 cooperates with the body ECU 17 to control the door locking mechanism. unlock. For example, if the position estimation unit F6 determines that the smartphone 2 is present in the vehicle interior and detects that the start button 15 has been pressed by the user, the engine is started in cooperation with the engine ECU 16. . In this way, the vehicle control unit F7 is basically configured to execute vehicle control according to the user's position and the state of the vehicle Hv using the user's operation on the vehicle Hv as a trigger. However, among the vehicle controls that can be performed by the vehicle control unit F7, there may be some that are automatically executed according to the user's position without requiring any user operation on the vehicle Hv.

[Position estimation processing]
Next, the position estimation process executed by the smart ECU 11 will be described using the flowchart shown in FIG. The position estimation process is a process for estimating the position of the smartphone 2. The position estimation process is performed at a predetermined position estimation cycle in a state where the connection between the BLE communication device 13 and the BLE communication unit 22 of the smartphone 2 is established. The position estimation cycle is, for example, 200 milliseconds. Of course, the position estimation cycle may be 100 milliseconds or 300 milliseconds.

Among the steps shown in FIG. 11, steps S12 and S21 (steps will be omitted hereinafter) are executed by the position estimating unit F6, and S14 to S19 are executed by the correction time calculating unit F4. S11, S13, and S20 are executed by the distance estimation unit F5. Note that the correction time calculation unit F4 and the distance estimation unit F5 execute processing in cooperation with the communication processing unit F2. The distance estimation unit F5 executes various processes for each UWB communication device 12.

First, in S11, distance estimation is performed in normal mode. In the normal mode, the frequency band used is the low UWB band, and the response request signal is transmitted as an impulse signal. When an impulse signal, which is a response signal, is received in response to this response request signal, the propagation time Ta is calculated from Equation 4 above. Note that before the correction time ΔT is calculated by the correction time calculation unit F4, a preset default value is used as the correction time ΔT. The default value may be, for example, a nominal value provided by the manufacturer.

S12 is executed when three or more UWB communication devices 12 are calculating the distance to the smartphone 2. In S12, the position of the smartphone 2 is estimated based on the installation position of each UWB communication device 12 and the distance from each UWB communication device 12 to the smartphone 2.

The installation position of each UWB communication device 12 may be determined using communication device position data stored in the flash memory 112. Estimating the position based on the installation position of each UWB communication device 12 and the distance from each UWB communication device 12 to the smartphone 2 can be performed using the principle of triangulation. There are various position estimation methods using the installation position of each UWB communication device 12 and the distance to the smartphone 2, such as the least squares method, the Newton-Raphson method, and the minimum mean square estimate (MMSE). algorithm can be adopted.

The position of the smartphone 2 estimated as described above (hereinafter referred to as the terminal position) is referred to by the vehicle control unit F7 and the like. For example, it is determined whether the terminal position corresponds to an operating area or a vehicle interior. If the terminal position falls within the operating area, the vehicle control unit F7 unlocks or locks the door based on the determination result. Further, when the terminal position corresponds to the inside of the vehicle, the vehicle control unit F7 starts the traveling drive source based on the determination result.

In S13, based on the position estimated in S12, it is determined whether the position is a high-frequency mode-enabled position. The conditions determined in S13 are broadband conditions. Since the high frequency mode has a shorter communication distance than the normal mode, an area where it can be estimated that the high frequency mode is possible is set in advance. If the position estimated in S12 is within this preset area, it is determined that it is a high frequency mode possible position. The high frequency mode possible position means that the distance between the smartphone 2 and the UWB communication device 12 is a distance where the high frequency mode is possible, that is, a high frequency possible distance.

If the determination result in S13 is NO, the process returns to S11. On the other hand, if the determination result in S13 is YES, the process advances to S14. In S14, it is determined whether it is necessary to calculate the correction time ΔT. In this embodiment, the correction time ΔT is calculated once after the UWB communication connection is established. Thereafter, the correction time ΔT is not calculated again while the connection is established. The correction time ΔT varies depending on various factors such as the communication environment and individual differences between devices, but the individual differences between devices are not a factor that changes during connection establishment, and the communication environment also does not change much during connection establishment. It is from.

If the determination result in S14 is NO, the process directly advances to S20. If the determination result in S14 is YES, the process advances to S15. In S15, a response request signal is transmitted and a response signal is received in the normal mode, and the round trip time Tp (hereinafter referred to as Tp(n)) is measured. In S16, the high frequency mode is instructed to the smartphone 2. In S17, the UWB communication device 12 is changed to high frequency mode.

In S18, the round trip time Tp is measured in high frequency mode. By continuously executing S15 to S18, response request signals and response signals having different time widths are continuously transmitted and received in the low UWB band and the high UWB band. Since the signal is transmitted and received continuously, it can be considered that the position of the smartphone 2 does not change when the low UWB band is used and when the high UWB band is used.

In S19, a correction time ΔT is calculated by subtracting the round trip time Tp(n) measured in S15 from the round trip time Tp(c) measured in S18, and the calculated correction time ΔT is stored in the flash memory 112. .

In S20, the distance to the smartphone 2 is estimated in high frequency mode. S21 is executed when three or more UWB communication devices 12 are calculating the distance to the smartphone 2. In S21, the position of the smartphone 2 is estimated based on the installation position of each UWB communication device 12 and the distance from each UWB communication device 12 to the smartphone 2. After executing S21, the process returns to S13.

[Summary of embodiments]
In the present embodiment described above, when the high frequency mode is possible (S13: YES), it is assumed that the wideband condition is satisfied, and the high frequency mode, that is, the mode in which the frequency band of the impulse signal is made wider than the normal mode. , the distance to the smartphone 2 is estimated (S20). By widening the frequency band of the impulse signal, the time width of the impulse signal becomes narrower in the time domain. Therefore, the error occurring in the impulse signal detection time is reduced, so the accuracy of estimating the distance to the smartphone 2 is improved.

Furthermore, in the present embodiment, if the smartphone 2 is located at a high-frequency mode-enabled position and the correction time ΔT has not been calculated (S14: YES), the round-trip time Tp is calculated in the normal mode and the high-frequency mode, respectively. (n) and Tp(c) are measured (S15, S18), and a correction time ΔT is calculated from the round trip times Tp(n) and Tp(c) (S19).

In the normal mode, the propagation time Ta is calculated using Equation 4, which is the sum of the round trip time Tp and the correction time ΔT. Thereby, even in the normal mode, the distance to the smartphone 2 can be estimated with accuracy close to that in the high frequency mode.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications described below are also included within the technical scope of the present disclosure. Various modifications and changes can be made without departing from the scope of the invention. For example, the various modifications described below can be implemented in appropriate combinations within a range that does not cause technical contradiction.

<Modification 1>
In the embodiment, an impulse signal with a narrow time width is exemplified as an impulse signal with a steep waveform rise. However, if the configuration is such that the low UWB band and the high UWB band can be used simultaneously, a composite signal obtained by combining a signal generated in the low UWB band and a signal generated in the high UWB band may be used as the impulse signal. The composite signal can also have a steeper waveform rise than an impulse signal generated using only the low UWB band.

<Modification 2>
In the embodiment, when widening the band, the frequency band is shifted to a higher frequency band to widen the band. However, the band may be widened without shifting to a high frequency band. In some countries, the frequency band allocated to UWB communications is not divided into two. For example, some countries allocate 3.1 to 10.6 GHz for UWB communications. In such a country, it is assumed that the UWB communication device 12 and the UWB communication unit 21 generate impulse signals using only a part of the frequency band from 3.1 to 10.6 GHz in normal mode. . In this case, the frequency to be used can include the frequency band used in the normal mode, but can also be a wider frequency band, for example, the entire range from 3.1 to 10.6 GHz.

Even if you do not shift to a high frequency band, by using a wideband mode only when necessary, in the normal mode, you can use a wideband mode while suppressing interference with other wireless communications. In this mode, the distance to the smartphone 2 can be estimated with high accuracy.

Furthermore, even if the frequency band is not shifted to a high frequency band, the distance estimation accuracy in the normal mode can be improved by calculating the correction time ΔT in the broadband mode.

<Modification 3>
In the embodiment, it is determined whether the distance to the smartphone 2 is a high frequency possible distance based on the distance estimated by the distance estimation unit F5. However, this distance estimating section F5 may be used as a first distance estimating section, and a second distance estimating section that estimates the distance to the smartphone 2 may be provided separately. The second distance estimation unit estimates the distance from the respective current positions of the UWB communication device 12 and the smartphone 2, which are determined using a GNSS receiver, for example. Such a second distance estimation unit acquires the current position from the GNSS receiver provided in the vehicle Hv, and uses the current position of the GNSS receiver and the UWB communication device 12 for the GNSS receiver measured in advance. The current position of the UWB communication device 12 is determined from the relative position of . The current location of the smartphone 2 is also acquired. Then, the distance to the smartphone 2 is estimated from the current location of the UWB communication device 12 and the current location of the smartphone 2. Further, the second distance estimation section may be configured to estimate the distance from the camera image.

<Modification 4>
In the embodiment, the correction time ΔT is calculated only once after the connection is established. However, the correction time ΔT may be calculated each time the distance is estimated. In this case, the determination in S14 may be omitted. The correction time ΔT also varies depending on the communication environment. Therefore, strictly speaking, the correction time ΔT changes each time the distance is estimated. Therefore, if the correction time ΔT is calculated every time the distance is estimated, the distance estimation accuracy will be improved.

<Modification 5>
In addition, since the correction time ΔT varies depending on the communication environment, a sensor or the like is installed to detect changes in the communication environment, and the correction time ΔT is compared with the current communication environment when the correction time ΔT was previously calculated. It may be determined whether or not to perform communication by recalculating the time ΔT.

An example of a sensor that detects changes in the communication environment is a sensor that detects ambient temperature. This is because when estimating the distance using the round trip time Tp, fluctuations at the nanosecond level become a problem, and the signal transmission time within the electronic circuit fluctuates at the nanosecond level due to temperature changes. Another example of a sensor that detects a change in the communication environment is a sensor that monitors the energization state of an antenna.

<Modification 5>
In the embodiment, when the correction time ΔT is calculated, the correction time ΔT stored in the flash memory 112 is always updated to the calculated correction time ΔT. However, after calculating the correction time ΔT, the difference from the nominal value may be calculated, and if the difference is larger than the update threshold, the correction time ΔT may be updated to the newly calculated correction time ΔT.

<Modification 6>
In the embodiment, the smartphone 2 is illustrated as the mobile terminal. However, as the mobile terminal, devices other than the smartphone 2 can also be used, such as a tablet terminal or a wearable terminal.

<Modification 7>
The in-vehicle system 1 of the embodiment was equipped with four UWB communication devices 12. However, when estimating the position of the smartphone 2, the number of UWB communication devices 12 may be three or more.

<Modification 8>
In the embodiment, after estimating three or more distances from the UWB communication device 12 to the smartphone 2, the position of the smartphone 2 is estimated based on the distances. However, it may be determined whether or not to permit operation of the in-vehicle device based on the distance to the smartphone 2 without estimating the location.

1: In-vehicle system 2: Smartphone (mobile terminal) 11: Smart ECU 12: UWB communication device (in-vehicle communication device) 13: BLE communication device 21: UWB communication section 22: BLE communication section 24: GNSS receiver 27: Input device 28 : Terminal side control section 29: Position detection section 111: CPU 112: Flash memory 113: RAM 310: Transmission section 311: Transmission circuit 312: Transmission antenna 313: Impulse generator 314: Variable bandpass filter 315: Amplifier 320: Receiving section 321: Receiving antenna 322: Receiving circuit 323: Amplifier 324: Detector 330: Round trip time measurement unit F1: Vehicle information acquisition unit F2: Communication processing unit F3: Authentication processing unit F4: Correction time calculation unit F5: Distance estimation unit F6 : Position estimation unit F7: Vehicle control unit Hv: Vehicle TH: Detection threshold Ta: Propagation time Tb: Internal processing time Tp: Round trip time ΔT: Correction time ΔTc: Time difference ΔTm: Time difference

Claims (14)

an on-vehicle communication device (12) that is mounted on a vehicle (Hv) and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
a mobile terminal (2) that is carried by a user, receives the response request signal through ultra-wideband communication, and transmits a response signal, which is an impulse signal, to the in-vehicle communication device when receiving the response request signal;
The distance between the in-vehicle communication device and the mobile terminal is estimated based on a round-trip time (Tp) from when the in-vehicle communication device transmits the response request signal to when it receives the response signal. A mobile terminal distance estimation system comprising a distance estimation unit (F5),
The mobile terminal sets the time when the reception strength of the response request signal exceeds a detection threshold as the time when the response request signal is received,
The in-vehicle communication device sets the time when the reception strength of the response signal exceeds a detection threshold as the time when the response signal is received,
The in-vehicle communication device and the mobile terminal have a variable frequency band for the ultra-wideband communication,
The in-vehicle communication device and the mobile terminal determine that a wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimating unit is equal to or less than a high frequency possible distance;
When it is determined that the wideband condition is satisfied, the in-vehicle communication device and the mobile terminal widen the communication frequency to make the rise of the waveform with a shorter time width steeper than when the wideband condition is not satisfied. transmitting and receiving the impulse signal set to
The mobile terminal and the in-vehicle communication device determine the widened frequency band based on the country in which the mobile terminal and the in-vehicle communication device are located,
comprising an input device (27) for a user to input the country;
A mobile terminal distance estimation system, wherein the mobile terminal and the in-vehicle communication device determine a country based on information input from the input device . an on-vehicle communication device (12) that is mounted on a vehicle (Hv) and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
a mobile terminal (2) that is carried by a user, receives the response request signal through ultra-wideband communication, and transmits a response signal, which is an impulse signal, to the in-vehicle communication device when receiving the response request signal;
The distance between the in-vehicle communication device and the mobile terminal is estimated based on a round-trip time (Tp) from when the in-vehicle communication device transmits the response request signal to when it receives the response signal. A mobile terminal distance estimation system comprising a distance estimation unit (F5),
The mobile terminal sets the time when the reception strength of the response request signal exceeds a detection threshold as the time when the response request signal is received,
The in-vehicle communication device sets the time when the reception strength of the response signal exceeds a detection threshold as the time when the response signal is received,
The in-vehicle communication device and the mobile terminal have a variable frequency band for the ultra-wideband communication,
The in-vehicle communication device and the mobile terminal determine that a wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimating unit is equal to or less than a high frequency possible distance;
When it is determined that the wideband condition is satisfied, the in-vehicle communication device and the mobile terminal widen the communication frequency to make the rise of the waveform with a shorter time width steeper than when the wideband condition is not satisfied. transmitting and receiving the impulse signal set to
The mobile terminal and the in-vehicle communication device determine the widened frequency band based on the country in which the mobile terminal and the in-vehicle communication device are located,
comprising a position detection unit (29) that detects the position of the mobile terminal or the in-vehicle communication device;
A mobile terminal distance estimation system, wherein the mobile terminal and the in-vehicle communication device determine the country based on the position detected by the position detection unit . The mobile terminal distance estimation system according to claim 1 or 2,
In the mobile terminal distance estimating system, the in-vehicle communication device and the mobile terminal shift the frequency band to a high frequency band to widen the communication frequency when widening the communication frequency. an on-vehicle communication device (12) that is mounted on a vehicle (Hv) and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
a mobile terminal (2) that is carried by a user, receives the response request signal through ultra-wideband communication, and transmits a response signal, which is an impulse signal, to the in-vehicle communication device when receiving the response request signal;
The distance between the in-vehicle communication device and the mobile terminal is estimated based on a round-trip time (Tp) from when the in-vehicle communication device transmits the response request signal to when it receives the response signal. A mobile terminal distance estimation system comprising a distance estimation unit (F5),
The mobile terminal sets the time when the reception strength of the response request signal exceeds a detection threshold as the time when the response request signal is received,
The in-vehicle communication device sets the time when the reception strength of the response signal exceeds a detection threshold as the time when the response signal is received,
The in-vehicle communication device and the mobile terminal have a variable frequency band for the ultra-wideband communication,
The in-vehicle communication device and the mobile terminal determine that a wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimating unit is equal to or less than a high frequency possible distance;
When it is determined that the wideband condition is satisfied, the in-vehicle communication device and the mobile terminal widen the communication frequency to make the rise of the waveform with a shorter time width steeper than when the wideband condition is not satisfied. transmitting and receiving the impulse signal set to
When widening the communication frequency, the in-vehicle communication device and the mobile terminal shift the frequency band to a high frequency band to widen the frequency band,
The distance estimation unit periodically estimates a distance,
A mobile terminal distance estimating system , wherein the distance for determining whether the broadbanding condition is satisfied is the latest distance estimated by the distance estimating unit . an on-vehicle communication device (12) that is mounted on a vehicle (Hv) and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
a mobile terminal (2) that is carried by a user, receives the response request signal through ultra-wideband communication, and transmits a response signal, which is an impulse signal, to the in-vehicle communication device when receiving the response request signal;
The distance between the in-vehicle communication device and the mobile terminal is estimated based on a round-trip time (Tp) from when the in-vehicle communication device transmits the response request signal to when it receives the response signal. A mobile terminal distance estimation system comprising a distance estimation unit (F5),
The mobile terminal sets the time when the reception strength of the response request signal exceeds a detection threshold as the time when the response request signal is received,
The in-vehicle communication device sets the time when the reception strength of the response signal exceeds a detection threshold as the time when the response signal is received,
The in-vehicle communication device and the mobile terminal have a variable frequency band for the ultra-wideband communication,
The in-vehicle communication device and the mobile terminal determine that a wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimating unit is equal to or less than a high frequency possible distance;
When it is determined that the wideband condition is satisfied, the in-vehicle communication device and the mobile terminal widen the communication frequency to make the rise of the waveform with a shorter time width steeper than when the wideband condition is not satisfied. transmitting and receiving the impulse signal set to
When widening the communication frequency, the in-vehicle communication device and the mobile terminal shift the frequency band to a high frequency band to widen the frequency band,
The distance estimator is a first distance estimator,
comprising a second distance estimation unit that estimates the distance between the mobile terminal and the in-vehicle communication device by a means different from the round trip time;
The distance for determining whether the broadbanding condition is satisfied is the distance estimated by the second distance estimating unit . an on-vehicle communication device (12) that is mounted on a vehicle (Hv) and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
a mobile terminal (2) that is carried by a user, receives the response request signal through ultra-wideband communication, and transmits a response signal, which is an impulse signal, to the in-vehicle communication device when receiving the response request signal;
The distance between the in-vehicle communication device and the mobile terminal is estimated based on a round-trip time (Tp) from when the in-vehicle communication device transmits the response request signal to when it receives the response signal. A mobile terminal distance estimation system comprising a distance estimation unit (F5),
The mobile terminal sets the time when the reception strength of the response request signal exceeds a detection threshold as the time when the response request signal is received,
The in-vehicle communication device sets the time when the reception strength of the response signal exceeds a detection threshold as the time when the response signal is received,
The in-vehicle communication device and the mobile terminal have a variable frequency band for the ultra-wideband communication,
The in-vehicle communication device and the mobile terminal determine that a wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimating unit is equal to or less than a high frequency possible distance;
When it is determined that the wideband condition is satisfied, the in-vehicle communication device and the mobile terminal widen the communication frequency to make the rise of the waveform with a shorter time width steeper than when the wideband condition is not satisfied. transmitting and receiving the impulse signal set to
Assuming that the broadbanding condition is satisfied in the case of communication for calculating a correction time (ΔT) for correcting the round trip time,
The in-vehicle communication device continuously sends the response requests with different time widths in the widened frequency band and in a frequency band that is relatively narrow compared to the widened frequency band. send a signal,
The mobile terminal transmits the response signal when receiving the response request signal in the wideband frequency band and the narrowband frequency band, respectively,
a correction time calculation unit (F4) that calculates the difference between the round trip time calculated using the widened frequency band and the round trip time calculated using the narrow frequency band as the correction time ),
When the round trip time is calculated in the narrow frequency band, the distance estimation unit estimates the distance to the mobile terminal based on the round trip time plus the correction time. Mobile terminal distance estimation system. The mobile terminal distance estimation system according to claim 6 ,
A mobile terminal distance estimating system, wherein communication for calculating the correction time is performed each time the distance estimating unit estimates the distance. The mobile terminal distance estimation system according to claim 6 ,
A mobile terminal distance estimation system that performs communication for calculating the correction time once after communication between the mobile terminal and the in-vehicle communication device is established. The mobile terminal distance estimation system according to claim 6 ,
A mobile terminal distance estimating system that compares a communication environment when the correction time was previously calculated with a current communication environment to determine whether or not to perform communication for calculating the correction time. an on-vehicle communication device (12) that is mounted on the vehicle and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
Based on the round trip time (Tp) from when the in-vehicle communication device transmits the response request signal until it receives the response signal, which is the impulse signal, transmitted from the mobile terminal carried by the user, An in-vehicle system comprising a distance estimation unit (F5) that estimates a distance between an in-vehicle communication device and the mobile terminal,
The in-vehicle communication device is
The time when the reception strength of the response signal exceeds the detection threshold is the time when the response signal is received,
The frequency band for the ultra-wideband communication is variable,
The in-vehicle communication device determines that a wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimation unit is less than or equal to a high frequency possible distance;
If it is determined that the wideband condition is satisfied, transmitting the impulse signal with a steeper rise of a waveform with a shorter time width by making the communication frequency wider than when the wideband condition is not satisfied;
The in-vehicle communication device determines the widened frequency band based on the country in which the in-vehicle communication device is located,
comprising an input device for a user to input the country;
The in-vehicle communication device is an in-vehicle system that determines a country based on information input from the input device . an on-vehicle communication device (12) that is mounted on the vehicle and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
Based on the round trip time (Tp) from when the in-vehicle communication device transmits the response request signal until it receives the response signal, which is the impulse signal, transmitted from the mobile terminal carried by the user, An in-vehicle system comprising a distance estimation unit (F5) that estimates a distance between an in-vehicle communication device and the mobile terminal,
The in-vehicle communication device is
The time when the reception strength of the response signal exceeds the detection threshold is the time when the response signal is received,
The frequency band for the ultra-wideband communication is variable,
The in-vehicle communication device determines that a wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimation unit is less than or equal to a high frequency possible distance;
If it is determined that the wideband condition is satisfied, transmitting the impulse signal with a steeper rise of a waveform with a shorter time width by making the communication frequency wider than when the wideband condition is not satisfied;
The in-vehicle communication device determines the widened frequency band based on the country in which the in-vehicle communication device is located,
comprising a position detection unit that detects the position of the mobile terminal or the in-vehicle communication device,
The in-vehicle communication device is an in-vehicle system that determines the country based on the position detected by the position detection unit . an on-vehicle communication device (12) that is mounted on the vehicle and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
Based on the round trip time (Tp) from when the in-vehicle communication device transmits the response request signal until it receives the response signal, which is the impulse signal, transmitted from the mobile terminal carried by the user, An in-vehicle system comprising a distance estimation unit (F5) that estimates a distance between an in-vehicle communication device and the mobile terminal,
The in-vehicle communication device is
The time when the reception strength of the response signal exceeds the detection threshold is the time when the response signal is received,
The frequency band for the ultra-wideband communication is variable,
The in-vehicle communication device determines that a wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimation unit is less than or equal to a high frequency possible distance;
If it is determined that the wideband condition is satisfied, transmitting the impulse signal with a steeper rise of a waveform with a shorter time width by making the communication frequency wider than when the wideband condition is not satisfied;
When widening the communication frequency, the in-vehicle communication device shifts the frequency band to a high frequency band to widen the frequency band,
The distance estimation unit periodically estimates a distance,
In the vehicle-mounted system , the distance for determining whether the broadbanding condition is satisfied is the latest distance estimated by the distance estimation unit . an on-vehicle communication device (12) that is mounted on the vehicle and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
Based on the round trip time (Tp) from when the in-vehicle communication device transmits the response request signal until it receives the response signal, which is the impulse signal, transmitted from the mobile terminal carried by the user, An in-vehicle system comprising a distance estimation unit (F5) that estimates a distance between an in-vehicle communication device and the mobile terminal,
The in-vehicle communication device is
The time when the reception strength of the response signal exceeds the detection threshold is the time when the response signal is received,
The frequency band for the ultra-wideband communication is variable,
The in-vehicle communication device determines that a wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimation unit is less than or equal to a high frequency possible distance;
If it is determined that the wideband condition is satisfied, transmitting the impulse signal with a steeper rise of a waveform with a shorter time width by making the communication frequency wider than when the wideband condition is not satisfied;
When widening the communication frequency, the in-vehicle communication device shifts the frequency band to a high frequency band to widen the frequency band,
The distance estimator is a first distance estimator,
comprising a second distance estimation unit that estimates the distance between the mobile terminal and the in-vehicle communication device by a means different from the round trip time;
The in-vehicle system is characterized in that the distance for determining whether the broadbanding condition is satisfied is the distance estimated by the second distance estimating unit . an on-vehicle communication device (12) that is mounted on the vehicle and transmits a response request signal, which is an impulse signal, through ultra-wideband communication;
Based on the round trip time (Tp) from when the in-vehicle communication device transmits the response request signal until it receives the response signal, which is the impulse signal, transmitted from the mobile terminal carried by the user, An in-vehicle system comprising a distance estimation unit (F5) that estimates a distance between an in-vehicle communication device and the mobile terminal,
The in-vehicle communication device is
The time when the reception strength of the response signal exceeds the detection threshold is the time when the response signal is received,
The frequency band for the ultra-wideband communication is variable,
The in-vehicle communication device determines that a wideband condition is satisfied when the distance between the mobile terminal and the in-vehicle communication device estimated by the distance estimation unit is less than or equal to a high frequency possible distance;
If it is determined that the wideband condition is satisfied, transmitting the impulse signal with a steeper rise of a waveform with a shorter time width by making the communication frequency wider than when the wideband condition is not satisfied;
Assuming that the broadbanding condition is satisfied in the case of communication for calculating a correction time (ΔT) for correcting the round trip time,
The in-vehicle communication device continuously sends the response requests with different time widths in the widened frequency band and in a frequency band that is relatively narrow compared to the widened frequency band. send a signal,
The in-vehicle communication device transmits the response signal transmitted from the mobile terminal when the mobile terminal receives the response request signal in the wideband frequency band and the narrowband frequency band, respectively. receive and
a correction time calculation unit (F4) that calculates the difference between the round trip time calculated using the widened frequency band and the round trip time calculated using the narrow frequency band as the correction time ),
When the round trip time is calculated in the narrow frequency band, the distance estimation unit estimates the distance to the mobile terminal based on the round trip time plus the correction time. In-vehicle system.

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