JP2018137610A - Communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system capable of suppressing expansion of a configuration while including an interference avoidance function for confirming the presence/absence of a radio wave in a frequency band to be used.SOLUTION: In a vehicle 1 of an electronic key system, the presence/absence of a radio wave in a second UHF band is confirmed by a second UHF receiver of the vehicle 1, and a result of the presence/absence of a radio wave in the second UHF band is transmitted from an LF outdoor transmitter and an LF indoor transmitter of the vehicle 1 by a radio wave of an LF band. When a result showing the absence of a radio wave in a first UHF band is received by a second UHF receiver of the vehicle 1, a radio wave in the first UHF band is transmitted by the first UHF transmitter of the vehicle 1. When a result showing the absence of a radio wave in the second UHF band is received by a first UHF receiving part of an electronic key 2 of the electronic key system, in the electronic key 2, the presence/absence of a radio wave in the first UHF band is confirmed by the first UHF receiving part of the electronic key 2, and a result showing the presence/absence of a radio wave in the first UHF band is transmitted from a second UHF transmitting part of the electronic key 2 by a radio wave in the second UHF band.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a communication system.

  2. Description of the Related Art Conventionally, communication systems that perform ID verification by wirelessly transmitting a key ID from an electronic key to the vehicle in a vehicle or the like are well known. By the way, in this type of communication system, there is a fraudulent act using a repeater (see a repeater use fraud: see Patent Document 1, etc.) as a fraudulent act intended to establish ID verification without depending on the user's will. is there. For example, when the electronic key is located at a location far from the vehicle, the repeater use fraudulent act is an act of establishing a communication between these two parties by connecting the electronic key to the vehicle by a plurality of repeaters and relaying radio waves. is there. Therefore, since ID verification is established without the user's knowledge, there is a possibility that the door is unlocked or the engine is illegally operated by a third party.

  Therefore, there is a system for determining communication fraud by detecting the received signal strength in wireless communication between the vehicle and the electronic key and confirming the correlation between the received signal strengths as a countermeasure against fraudulent use of the repeater ( Patent Document 2).

JP 2006-161545 A JP 2012-60482 A

  By the way, in a communication system such as that described above that performs mutual communication using a plurality of frequency bands, there are countries that require an interference avoidance function for confirming whether radio waves exist in the frequency bands to be used. For this reason, in order to make the interference avoidance function effective, it is necessary to have a receiver for the frequency band having only the transmitter, which may increase the configuration of the apparatus.

  The present invention has been made in view of such circumstances, and its purpose is to suppress an increase in configuration while having an interference avoidance function for confirming whether or not radio waves are present in the frequency band to be used. It is to provide a communication system that can be used.

  A communication system that solves the above problems includes a first frequency band radio wave, a second frequency band radio wave that is different from the first frequency band, and a frequency different from the first frequency band and the second frequency band. A communication system in which the first communication device and the second communication device communicate with each other using radio waves in three frequency bands, which are radio waves in the third frequency band, which is a band, wherein the first communication device includes: A first transmitter that transmits radio waves in the first frequency band; a first receiver that receives radio waves in the second frequency band; and a second transmitter that transmits radio waves in the third frequency band. The second communication device receives a first receiver that receives radio waves in the first frequency band, a first transmitter that transmits radio waves in the second frequency band, and radio waves in the third frequency band. A second receiver, wherein the first communication device is the first communication device. The presence / absence of radio waves in the second frequency band is confirmed by one receiver, and the result of presence / absence of radio waves in the second frequency band is transmitted from the second transmitter of the first communication device as radio waves in the third frequency band. When the first receiver of the first communication device receives a result of no radio waves in the first frequency band, the radio waves in the first frequency band are transmitted by the first transmitter of the first communication device. When the second communication device receives a result of no radio waves in the second frequency band from the first receiver of the second communication device, the second communication device receives the result of the first receiver of the second communication device. The presence / absence of radio waves in one frequency band is confirmed, and the result of the presence / absence of radio waves in the first frequency band is transmitted from the first transmitter of the second communication device as radio waves in the second frequency band.

  According to the above configuration, the first communication device confirms whether or not there is a radio wave in the second frequency band, and transmits the result to the second communication device, so that the second communication device receives the radio wave in the second frequency band. It is possible to transmit radio waves in the second frequency band after confirming the presence / absence of radio waves in the second frequency band without having a receiver. In addition, the second communication device confirms the presence or absence of radio waves in the first frequency band, and transmits the result to the first communication device, so that the first communication device receives a receiver that receives radio waves in the first frequency band. Without having it, it is possible to transmit radio waves in the first frequency band after confirming the presence or absence of radio waves in the first frequency band. Therefore, it is possible to suppress an increase in configuration while having an interference avoidance function for confirming whether or not radio waves are present in the first frequency band and the second frequency band, which are frequency bands to be used.

  In the communication system, the first frequency band is a frequency band that requires an interference avoidance function for confirming whether radio waves are present in the frequency band to be used, and the second frequency band is the interference avoidance function. The third frequency band is preferably a frequency band that does not require the interference avoidance function.

  According to the above configuration, the communication system transmits the result of the presence / absence of the radio wave of the second frequency band that requires the interference avoidance function using the radio wave of the third frequency band that does not require the interference avoidance function. The presence or absence of radio waves can be confirmed. The communication system transmits the result of the presence / absence of the radio wave in the first frequency band that requires the interference avoidance function using the radio wave in the second frequency band in which the presence / absence of the radio wave can be confirmed. The presence or absence of radio waves can be confirmed.

  In the communication system, the first communication device transmits an activation signal for activating the second communication device from the second transmitter of the first communication device using radio waves in the third frequency band, and the activation signal is transmitted. Before transmission, the presence or absence of radio waves in the second frequency band is confirmed by the first receiver of the first communication device, and the result of presence or absence of radio waves in the second frequency band is sent together with the activation signal to the first communication. It is preferable that the second transmitter of the apparatus transmits the radio wave in the third frequency band.

  According to the above configuration, the presence / absence of the radio wave in the second frequency band is transmitted by transmitting the result of the presence / absence of the radio wave in the second frequency band together with the activation signal from the second transmitter of the first communication device using the radio wave in the third frequency band. Can be included in the communication monitoring between the first communication device and the second communication device.

  In the communication system, the second communication device receives the activation signal transmitted from the first communication device by the second receiver of the second communication device using radio waves in the third frequency band. A response signal to the signal is transmitted from the first transmitter by radio waves in the second frequency band, and before transmitting the response signal, the presence or absence of radio waves in the first frequency band is determined by the first communication device. It is preferable to confirm with a receiver and transmit the result of presence / absence of radio waves in the first frequency band together with the response signal from the first transmitter of the second communication device using radio waves in the second frequency band.

  According to the above configuration, the presence / absence of radio waves in the first frequency band is transmitted by transmitting the result of the presence / absence of radio waves in the first frequency band together with the response signal from the first transmitter of the second communication device using radio waves in the second frequency band. Can be included in the communication monitoring between the first communication device and the second communication device.

  About the communication system, using the first frequency band and the second frequency band, the unauthorized communication is determined by measuring a propagation distance in mutual communication between the first communication device and the second communication device. Is preferred.

According to the above configuration, by using the first frequency band and the second frequency band, it is possible to determine unauthorized communication based on the propagation distance in the frequency band avoiding interference.
A communication system that solves the above problems includes a first frequency band radio wave, a second frequency band radio wave that is different from the first frequency band, and a frequency different from the first frequency band and the second frequency band. A communication system in which the first communication device and the second communication device communicate with each other using radio waves in three frequency bands, which are radio waves in the third frequency band, which is a band, wherein the first communication device includes: A first transmitter that transmits radio waves in the first frequency band; a first receiver that receives radio waves in the second frequency band; and a second transmitter that transmits radio waves in the third frequency band. The second communication device receives a first receiver that receives radio waves in the first frequency band, a first transmitter that transmits radio waves in the second frequency band, and radio waves in the third frequency band. A second receiver, wherein the second communication device is the second communication device. The presence / absence of radio waves in the first frequency band is confirmed by one receiver, and the result of the presence / absence of radio waves in the first frequency band is transmitted from the first transmitter of the second communication device as radio waves in the second frequency band. When the first communication device receives a result of no radio waves in the first frequency band, the first communication device transmits radio waves in the first frequency band by the first transmitter of the first communication device.

  According to the above configuration, the second communication device confirms the presence or absence of the radio wave in the first frequency band, and transmits the result to the first communication device, so that the first communication device receives the radio wave in the first frequency band. It is possible to transmit radio waves in the first frequency band after confirming the presence / absence of radio waves in the first frequency band without having a receiver. Therefore, it is possible to suppress an increase in configuration while having an interference avoidance function for confirming whether or not radio waves are present in the first frequency band that is the frequency band to be used.

  In the communication system, the first frequency band is a frequency band that requires an interference avoidance function for confirming whether radio waves are present in the frequency band to be used, and the second frequency band is the interference avoidance function. Is unnecessary and is a frequency band different from the first frequency band, and the third frequency band is a frequency band that does not require the interference avoidance function and is different from the first frequency band and the second frequency band. Is preferred.

  According to the above configuration, the communication system transmits the result of the presence / absence of the radio wave in the first frequency band that requires the interference avoidance function using the radio wave in the second frequency band that does not require the interference avoidance function, thereby The presence or absence of radio waves can be confirmed.

  About the said communication system, the propagation distance in the mutual communication of the said 1st communication apparatus and the said 2nd communication apparatus using the said 1st frequency band and any one of the said 2nd frequency band or the said 3rd frequency band It is preferable to determine unauthorized communication by measuring.

  According to the above configuration, by using the first frequency band, it is possible to determine unauthorized communication based on the propagation distance using at least one frequency band that avoids interference.

  ADVANTAGE OF THE INVENTION According to this invention, the increase in a structure can be suppressed, having an interference avoidance function which confirms whether the electromagnetic wave exists in the frequency band to be used.

The block diagram which shows schematic structure in 1st Embodiment of a communication system. The sequence chart which shows operation | movement of the communication system of the embodiment. The timing chart which shows operation | movement of the communication system of the embodiment. The sequence chart which shows the operation | movement in 2nd Embodiment of a communication system. The timing chart which shows operation | movement of the communication system of the embodiment.

(First embodiment)
A first embodiment in which the communication system is embodied as an electronic key system will be described below with reference to FIGS.

  As shown in FIG. 1, the vehicle 1 includes an electronic key system 3 that performs ID verification with the electronic key 2 by wireless communication. The electronic key system 3 is a key operation free system that performs ID collation with the electronic key 2 through narrow-range wireless communication in response to communication from the vehicle 1. Generally, ID collation performed in a key operation free system is called “smart collation”, and the communication is called “smart communication”. The electronic key system 3 corresponds to a communication system, the vehicle 1 corresponds to a first communication device, and the electronic key 2 corresponds to a second communication device.

  The vehicle 1 includes a collation ECU (Electronic Control Unit) 11 that performs ID collation (smart collation), a body ECU 12 that manages the power supply of the in-vehicle electrical components, and an engine ECU 13 that controls the engine 14. These ECUs are connected through a communication line 15 in the vehicle. The communication line 15 is made of, for example, a CAN (Controller Area Network) or a LIN (Local Interconnect Network). In the verification ECU 11, the key ID and the encryption key of the electronic key 2 registered in the vehicle 1 are written and stored in the memory 11a. The encryption key is used in challenge response authentication performed in the process of ID verification.

  The vehicle 1 includes an LF outdoor transmitter 16 that transmits LF (Low Frequency) band radio waves and an LF indoor transmitter 17 that transmits LF band radio waves indoors. The vehicle 1 includes a first UHF transmitter 18 that transmits radio waves in a first UHF (Ultra High Frequency) band in the vehicle 1, and a second UHF receiver 19 that receives radio waves in the second UHF band in the vehicle 1. The first UHF band and the second UHF band are different frequency bands in the UHF band, and are frequency bands that require an interference avoidance function for confirming whether radio waves exist in the frequency band to be used. For this reason, the electronic key system 3 performs LBT (Listen Before Talk) as interference avoidance for confirming whether or not there is a radio wave in a frequency band to be used before transmitting the first UHF band and the second UHF band. The electronic key system 3 authenticates the electronic key 2 through LF-UHF bidirectional communication and UHF-UHF bidirectional communication. The body ECU 12 switches the locking / unlocking of the door of the vehicle 1 by controlling the operation of the door lock mechanism 20 provided on the door of the vehicle 1. The first UHF band corresponds to the first frequency band, the second UHF band corresponds to the second frequency band, and the LF band corresponds to the third frequency band. The first UHF transmitter 18 of the vehicle 1 functions as the first transmitter of the first communication device, the second UHF receiver 19 of the vehicle 1 functions as the first receiver of the first communication device, and the LF outdoor transmission of the vehicle 1 The machine 16 and the LF indoor transmitter 17 function as a second transmitter of the first communication device.

  The electronic key 2 includes a key control unit 21 that controls the operation of the electronic key 2 and an LF receiving unit 22 that receives radio waves in the LF band in the electronic key 2. The electronic key 2 includes a first UHF receiver 23 that receives a first UHF band radio wave in the electronic key 2 and a second UHF transmitter 24 that transmits a second UHF band radio wave in the electronic key 2. In the key control unit 21, a key ID as an ID unique to the key and an encryption key used in challenge response authentication for ID verification are written and stored in the memory 21a. The first UHF receiver 23 functions as the first receiver of the second communication device, the second UHF transmitter 24 functions as the first transmitter of the second communication device, and the LF receiver 22 of the second communication device. It functions as a second receiver.

  The verification ECU 11 periodically transmits the wake signal Swk from the LF outdoor transmitter 16 or the LF indoor transmitter 17 by radio waves in the LF band, and monitors establishment of communication with the electronic key 2. When the verification ECU 11 receives the ACK signal Sack from the electronic key 2 that has received the wake signal Swk, the verification ECU 11 executes specific authentication communication. In addition, when the electronic key 2 receives the wake signal Swk, the electronic key 2 transmits the ACK signal Sack from the second UHF transmission unit 24 using the second UHF band radio wave. The wake signal Swk corresponds to the activation signal, and the ack signal Sack corresponds to a response signal to the activation signal. That is, the electronic key system 3 performs two-way communication of LF-UHF (second UHF) at the time of monitoring establishment of communication between the verification ECU 11 and the electronic key 2, and determines whether or not radio waves exist in the frequency band used at this time. The LBT communication to be confirmed is also performed.

  The electronic key system 3 includes a first LBT communication unit 31 that performs LBT communication. The first LBT communication unit 31 is provided in the verification ECU 11. Before transmitting the wake signal Swk, the first LBT communication unit 31 confirms the presence / absence of the second UHF band by the second UHF receiver 19 and the result of the presence / absence of the second UHF band radio wave together with the wake signal Swk to the LF outdoor transmitter 16. Alternatively, transmission is performed from the LF indoor transmitter 17 using radio waves in the LF band. The first LBT communication unit 31 permits the first UHF transmitter 18 to transmit the first UHF band radio wave when the second UHF receiver 19 receives the result without the first UHF band radio wave. That is, the electronic key system 3 uses the frequency band used when the vehicle 1 as the communication partner confirms the presence or absence of radio waves in the second UHF band in which the electronic key 2 transmits radio waves, and the reception result is received by the electronic key 2. Check if there is any radio wave. In other words, the electronic key system 3 confirms whether or not there is a radio wave in the second UHF band by the second UHF receiver 19 of the vehicle 1 acting as a substitute for receiving the second UHF band of the electronic key 2.

  The electronic key system 3 includes a second LBT communication unit 32 that performs LBT communication. The second LBT communication unit 32 is provided in the key control unit 21. When the second LBT communication unit 32 receives the result of the absence of the second UHF band radio wave by the LF reception unit 22, the first UHF reception unit 23 confirms the presence of the first UHF band radio wave before transmitting the ACK signal Sack. . Then, the second LBT communication unit 32 permits the transmission of the second UHF band radio wave from the second UHF transmission unit 24 together with the ACK signal Sack on the result of the presence or absence of the first UHF band radio wave. That is, the electronic key system 3 confirms the presence or absence of radio waves in the first UHF band from which the vehicle 1 transmits radio waves and the first UHF used by the vehicle 1 receiving the reception result after the reception result is received by the vehicle 1. Check if radio waves are present. In other words, the electronic key system 3 confirms whether or not there is a radio wave in the first UHF band by substituting the first UHF receiving unit 23 of the electronic key 2 for reception of the first UHF band of the vehicle 1.

  In addition, the electronic key system 3 performs authentication communication in which the electronic key 2 receives the transmission radio wave Sa from the verification ECU 11 and returns the return radio wave Sb from the electronic key 2. The verification ECU 11 transmits the transmission radio wave Sa in the LF band, and the electronic key 2 transmits the reply radio wave Sb in the second UHF band. That is, the electronic key system 3 performs LF-UHF (second UHF) bidirectional communication during authentication communication. ID verification is performed during authentication communication. For ID verification, key ID verification for confirming the correctness of the key ID registered in the electronic key 2, and challenge response for confirming the response code by calculating the challenge code with the encryption key in both the vehicle 1 and the electronic key 2 Includes authentication. In other words, the transmitted radio wave Sa transmitted from the verification ECU 11 to the electronic key 2 includes a challenge code for challenge response authentication. Further, the reply radio wave Sb transmitted from the electronic key 2 to the verification ECU 11 includes an ID code and a response code for challenge response authentication.

  Following the authentication communication, the electronic key system 3 causes the electronic key 2 to receive the first ranging signal Sc from the verification ECU 11 and returns the second ranging signal Sd from the electronic key 2 so that the propagation distance from these signals. Ranging communication is measured. The electronic key system 3 includes a measurement unit 33 that measures the propagation distance. The verification ECU 11 transmits the first ranging signal Sc in the first UHF band, and the electronic key 2 transmits the second ranging signal Sd in the second UHF band. That is, the electronic key system 3 performs UHF-UHF (first UHF-second UHF) bidirectional communication during distance measurement communication. The electronic key 2 generates the second ranging signal Sd by sending back the first ranging signal Sc transmitted from the verification ECU 11 as it is. Since the first ranging signal Sc and the second ranging signal Sd are mixed in the same frequency band, the first UHF band and the second UHF band, which are different frequency bands, are used. The measurement unit 33 obtains, for example, the phase rotation amount generated between the first distance measurement signal Sc and the second distance measurement signal Sd for each frequency band, and the gradient in the relationship between the frequency band and the phase rotation amount indicates the distance measurement signal. The propagation distance is measured by multiplying this delay time by the speed of light.

  The electronic key system 3 includes a correctness determination unit 34 that determines whether wireless communication between the verification ECU 11 and the electronic key 2 is correct. The correctness determination unit 34 is provided in the verification ECU 11. The correctness determination unit 34 determines whether unauthorized communication by a repeater or the like is not performed based on the propagation distance measured by distance measurement communication. The correctness determination unit 34 permits authentication communication when the propagation distance measured by the measurement unit 33 is equal to or smaller than the threshold, and disables authentication communication when the measured propagation distance is larger than the threshold.

Next, the operation of the electronic key system 3 will be described with reference to FIGS.
As shown in FIGS. 2 and 3, the electronic key system 3 performs wireless communication between the vehicle 1 and the electronic key 2 in the order of LBT communication, authentication communication, and distance measurement communication.

  First, in order to monitor establishment of communication with the electronic key 2, the vehicle 1 transmits a wake signal Swk but waits for reception in the second UHF band before transmitting the wake signal Swk (step S11). That is, the first LBT communication unit 31 confirms the presence or absence of the second UHF band by the second UHF receiver 19 before transmitting the wake signal Swk.

  The vehicle 1 transmits the reception result in the LF band (step S13). That is, the first LBT communication unit 31 transmits the result of the presence / absence of the second UHF band radio wave together with the wake signal Swk from the LF outdoor transmitter 16 or the LF indoor transmitter 17 using the LF band radio wave. Here, the second UHF receiver 19 does not receive the second UHF band radio wave (step S12), and the first LBT communication unit 31 transmits a reception result indicating that there is no second UHF band radio wave.

  Subsequently, when the electronic key 2 receives the wake signal Swk transmitted from the vehicle 1, the electronic key 2 confirms the reception result included in the wake signal Swk, and based on the reception result indicating that there is no radio wave in the second UHF band, Transmission is permitted (step S14). That is, the electronic key system 3 uses the second UHF used when the vehicle 1 as the communication partner confirms the presence or absence of radio waves in the second UHF band in which the electronic key 2 transmits radio waves, and the reception result is received by the electronic key 2. Check if there is any radio wave. In other words, the electronic key system 3 confirms whether or not there is a radio wave in the second UHF band by the second UHF receiver 19 of the vehicle 1 acting as a substitute for receiving the second UHF band of the electronic key 2.

  When receiving the wake signal Swk transmitted from the vehicle 1, the electronic key 2 transmits an ACK signal Sack as a response signal, but waits for reception of radio waves in the first UHF band before transmitting the ACK signal Sack (step S15). That is, the second LBT communication unit 32 confirms the presence or absence of the first UHF band by the first UHF receiving unit 23 before transmitting the ACK signal Sack.

  The electronic key 2 transmits the reception result in the second UHF band (step S17). That is, the second LBT communication unit 32 transmits the result of presence / absence of the first UHF band radio wave from the second UHF transmission unit 24 together with the ACK signal Sack by the second UHF band radio wave. Here, the first UHF receiving unit 23 does not receive the first UHF band radio wave (step S16), and the second LBT communication unit 32 transmits a reception result indicating that there is no first UHF band radio wave.

  Subsequently, when the vehicle 1 receives the ACK signal Sack transmitted from the electronic key 2, the vehicle 1 confirms the reception result included in the ACK signal Sack, and based on the reception result that there is no radio wave in the first UHF band, Transmission is permitted (step S18). That is, the electronic key system 3 confirms the presence or absence of radio waves in the first UHF band from which the vehicle 1 transmits radio waves and the first UHF used by the vehicle 1 receiving the reception result after the reception result is received by the vehicle 1. Check if radio waves are present. In other words, the electronic key system 3 confirms whether or not there is a radio wave in the first UHF band by substituting the first UHF receiving unit 23 of the electronic key 2 for reception of the first UHF band of the vehicle 1.

  The vehicle 1 transmits LF band radio waves (step S19). That is, the verification ECU 11 transmits a transmission radio wave Sa including a challenge code as an LF band radio wave from the LF outdoor transmitter 16 or the LF indoor transmitter 17 and performs authentication communication including challenge response authentication.

  Subsequently, when receiving the LF band transmission radio wave Sa transmitted from the vehicle 1, the electronic key 2 transmits the second UHF band radio wave (step S20). That is, the key control unit 21 transmits a return radio wave Sb including a response code as a second UHF band radio wave from the second UHF transmission unit 24, and performs authentication communication including challenge response authentication.

  Subsequently, the vehicle 1 transmits radio waves in the first UHF band (step S21). In other words, the verification ECU 11 transmits the first ranging signal Sc from the first UHF transmitter 18 as the first UHF band radio wave and performs ranging communication.

  Subsequently, the electronic key 2 transmits a radio wave in the second UHF band (step S22). That is, the key control unit 21 performs distance measurement communication by transmitting the second ranging signal Sd from the second UHF transmission unit 24 as a second UHF band radio wave. The key control unit 21 transmits the second distance measurement signal Sd by returning the first distance measurement signal Sc transmitted from the vehicle 1 as it is.

Subsequently, the correctness determination unit 34 of the vehicle 1 determines whether or not unauthorized communication is performed based on distance measurement communication.
As described above, according to this embodiment, the following effects can be obtained.

  (1) The vehicle 1 confirms the presence / absence of radio waves in the second UHF band and transmits the result to the electronic key 2, so that the electronic key 2 does not have a receiver for receiving radio waves in the second UHF band. It becomes possible to transmit the second UHF band radio wave after confirming the presence / absence of the 2UHF band radio wave. Further, the electronic key 2 confirms the presence / absence of radio waves in the first frequency band and transmits the result to the vehicle 1, so that the vehicle 1 does not have a receiver for receiving radio waves in the first UHF band, and the first UHF is received. The first UHF band radio wave can be transmitted after confirming the presence or absence of the radio wave of the band. Therefore, an increase in the configuration can be suppressed while having an interference avoidance function for confirming whether or not radio waves are present in the frequency band to be used.

  (2) The communication system confirms the presence / absence of radio waves in the second UHF band by transmitting the result of the presence / absence of radio waves in the second UHF band that requires the interference avoidance function using LF radio waves that do not require the interference avoidance function. be able to. Then, the communication system transmits the result of the presence / absence of the first UHF band radio wave, which requires the interference avoidance function, by using the second UHF band radio wave that can confirm the presence / absence of the radio wave. Can be confirmed.

  (3) By transmitting the result of the presence / absence of the second UHF band radio wave together with the wake signal Swk from the LF outdoor transmitter 16 and the LF indoor transmitter 17 of the vehicle 1 using the LF band radio wave, The result can be included in the communication monitoring between the vehicle 1 and the electronic key 2.

  (4) The result of the presence / absence of the first UHF band radio wave is transmitted together with the response signal from the second UHF transmission unit 24 of the electronic key 2 using the second UHF band radio wave. It can be included in communication monitoring with the electronic key 2.

(5) By using the first UHF band and the second UHF band that require the interference avoidance function, it is possible to determine unauthorized communication based on the propagation distance in the frequency band where interference is avoided.
(Second Embodiment)
Hereinafter, a second embodiment in which the communication system is embodied as an electronic key system will be described with reference to FIGS. 4 and 5. The communication system of this embodiment is different from the first embodiment in that it requires avoiding interference of radio waves in the first UHF band and avoiding interference of radio waves in the second UHF band and LF band. Hereinafter, a description will be given focusing on differences from the first embodiment.

  As shown in FIGS. 4 and 5, the electronic key system 3 confirms the presence or absence of radio waves in the first UHF band. The electronic key system 3 performs wireless communication between the vehicle 1 and the electronic key 2 in the order of authentication communication, LBT communication, and distance measurement communication.

  First, the vehicle 1 transmits LF band radio waves (step S31). In other words, the verification ECU 11 transmits the wake signal Swk from the LF outdoor transmitter 16 or the LF indoor transmitter 17 using LF band radio waves. In addition, when the vehicle 1 receives the ACK signal Sack from the electronic key 2, the vehicle 1 transmits a transmission radio wave Sa including a challenge code from the LF outdoor transmitter 16 or the LF indoor transmitter 17 using an LF band radio wave, and performs challenge response authentication. Including authentication communication.

  Subsequently, the electronic key 2 transmits the second UHF band radio wave (step S32). That is, the key control unit 21 transmits the ACK signal Sack from the second UHF transmission unit 24 using the second UHF band radio wave. In addition, when receiving the transmission radio wave Sa, the electronic key 2 transmits a reply radio wave Sb including a response code from the second UHF transmission unit 24 using the second UHF band radio wave, and performs authentication communication including challenge response authentication.

  The electronic key 2 waits for reception of radio waves in the first UHF band (step S33). That is, the second LBT communication unit 32 performs LBT communication before performing distance measurement communication. The second LBT communication unit 32 confirms the presence or absence of the first UHF band by the first UHF receiving unit 23.

  The electronic key 2 transmits the reception result using the second UHF band radio wave (step S35). That is, the second LBT communication unit 32 transmits the transmission radio wave Se from the second UHF transmission unit 24 using the result of the presence / absence of the first UHF radio wave as the second UHF radio wave. Here, the first UHF receiving unit 23 does not receive the first UHF band radio wave (step S34), and the second LBT communication unit 32 transmits a reception result indicating that there is no first UHF band radio wave.

  Subsequently, when the vehicle 1 receives the transmission radio wave Se transmitted from the electronic key 2, the vehicle 1 confirms the reception result included in the transmission radio wave Se, and based on the reception result that there is no radio wave in the first UHF band, Transmission of radio waves is permitted (step S36). That is, in the electronic key system 3, the electronic key 2 as a communication partner confirms the presence or absence of radio waves in the first UHF band in which the vehicle 1 transmits radio waves, and the reception result is received by the vehicle 1 in the frequency band to be used. Check if radio waves are present. In other words, the electronic key system 3 confirms whether or not there is a radio wave in the first UHF band by substituting the first UHF receiving unit 23 of the electronic key 2 for reception of the first UHF band of the vehicle 1.

  The vehicle 1 transmits the first UHF band radio wave (step S37). In other words, the verification ECU 11 transmits the first ranging signal Sc from the first UHF transmitter 18 as the first UHF band radio wave and performs ranging communication.

  Subsequently, the electronic key 2 transmits a second UHF band radio wave (step S38). That is, the key control unit 21 performs distance measurement communication by transmitting the second ranging signal Sd from the second UHF transmission unit 24 as a second UHF band radio wave. The key control unit 21 transmits the second distance measurement signal Sd by returning the first distance measurement signal Sc transmitted from the vehicle 1 as it is.

Subsequently, the correctness determination unit 34 of the vehicle 1 determines whether or not unauthorized communication is performed based on distance measurement communication.
As described above, according to this embodiment, the following effects can be obtained.

  (1) The electronic key 2 confirms the presence / absence of radio waves in the first UHF band and transmits the result to the vehicle 1 so that the vehicle 1 does not have a receiver for receiving radio waves in the first UHF band, and the first UHF band is received. The first UHF band radio wave can be transmitted after confirming the presence or absence of the radio wave of the band. Therefore, an increase in the configuration can be suppressed while having an interference avoidance function for confirming whether or not radio waves are present in the frequency band to be used.

  (2) The communication system confirms the presence / absence of the first UHF band radio wave by transmitting the result of the presence / absence of the first UHF band radio wave requiring the interference avoidance function using the second UHF band radio wave not requiring the interference avoidance function. can do.

(3) By using the first UHF band that requires the interference avoidance function, it is possible to determine unauthorized communication based on the propagation distance using at least one frequency band that avoids interference.
In addition, the said embodiment can also be implemented with the following forms which changed this suitably.

  In the above first embodiment, whether or not radio waves exist in the frequency band used during LBT communication is checked and communication establishment is monitored, but the frequency used separately from the communication establishment monitoring It may be confirmed whether or not radio waves exist in the band.

  In each of the above embodiments, the first UHF band, the second UHF band, and the LF band are adopted as the first frequency band, the second frequency band, and the third frequency band, but these frequency bands can be arbitrarily selected. In the first embodiment, the first frequency band and the second frequency band are frequency bands that require an interference avoidance function. In the second embodiment, the first frequency band is a frequency band that requires an interference avoidance function.

  In each of the above embodiments, the wake signal Swk, the transmission radio wave Sa, and the first distance measurement signal Sc are transmitted from the electronic key 2, and the ACK signal Sack, the return radio wave Sb, and the second distance measurement signal Sd are transmitted from the verification ECU 11. You may do it.

In each of the above embodiments, the correctness determination unit 34 may be provided in either the verification ECU 11 or the electronic key 2.
In each of the above embodiments, the presence / absence of unauthorized communication is confirmed based on distance measurement communication, but the presence / absence of unauthorized communication may be confirmed based on other numerical values such as received signal strength.

In each of the above embodiments, the electronic key system 3 is not limited to a system that performs smart communication, and may be a system that uses another communication format or frequency band.
In each of the above embodiments, the vehicle 1 is the first communication device, but is not limited to the vehicle 1 and can be changed to other devices and devices such as buildings.

In each of the above embodiments, the electronic key 2 is the second communication device. However, the electronic key 2 is not limited to the electronic key 2 and can be changed to another device or device.
In each of the above embodiments, the communication system is not limited to the electronic key system 3 applied to the vehicle 1 and may be employed in other devices and devices.

  In each of the above embodiments, the communication system may perform communication using either a half duplex method or a full duplex method.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Electronic key, 3 ... Electronic key system, 11 ... Verification ECU, 11a ... Memory, 12 ... Body ECU, 13 ... Engine ECU, 14 ... Engine, 15 ... Communication line, 16 ... LF outdoor transmitter, DESCRIPTION OF SYMBOLS 17 ... LF indoor transmitter, 18 ... 1st UHF transmitter, 19 ... 2nd UHF receiver, 20 ... Door lock mechanism, 21 ... Key control part, 21a ... Memory, 22 ... LF receiver, 23 ... 1st UHF receiver, 24 ... 2nd UHF transmission part, 31 ... 1st LBT communication part, 32 ... 2nd LBT communication part, 33 ... Measurement part, 34 ... Correct / fail judgment part, Sa ... Transmission radio wave, Sb ... Reply radio wave, Sack ... Ac signal, Sc ... 1st 1 ranging signal, Sd ... second ranging signal, Se ... transmitted radio wave, Swk ... wake signal.

Claims (8)

A radio wave in a first frequency band, a radio wave in a second frequency band that is a frequency band different from the first frequency band, and a radio wave in a third frequency band that is a frequency band different from the first frequency band and the second frequency band. A communication system in which the first communication device and the second communication device communicate with each other using radio waves in three frequency bands,
The first communication device includes a first transmitter that transmits radio waves in the first frequency band, a first receiver that receives radio waves in the second frequency band, and a first transmitter that transmits radio waves in the third frequency band. 2 transmitters,
The second communication device includes a first receiver that receives radio waves in the first frequency band, a first transmitter that transmits radio waves in the second frequency band, and a first receiver that receives radio waves in the third frequency band. 2 receivers,
The first communication device confirms the presence / absence of radio waves in the second frequency band by the first receiver of the first communication device, and determines the result of presence / absence of radio waves in the second frequency band of the first communication device. When the second transmitter transmits the radio wave in the third frequency band, and the first receiver of the first communication device receives a result of no radio wave in the first frequency band, the first communication device Transmitting radio waves in the first frequency band by the first transmitter;
When the second communication device receives a result of no radio wave in the second frequency band by the first receiver of the second communication device, the first frequency of the second communication device is determined by the first receiver of the second communication device. A communication system for confirming presence / absence of radio waves in a band and transmitting a result of presence / absence of radio waves in the first frequency band from the first transmitter of the second communication device using radio waves in the second frequency band. The first frequency band is a frequency band that requires an interference avoidance function for confirming whether radio waves are present in the frequency band to be used,
The second frequency band is a frequency band that requires the interference avoidance function,
The communication system according to claim 1, wherein the third frequency band is a frequency band that does not require the interference avoidance function. The first communication device transmits an activation signal for activating the second communication device from the second transmitter of the first communication device using radio waves in the third frequency band,
Before transmitting the activation signal, the presence or absence of radio waves in the second frequency band is confirmed by the first receiver of the first communication device, and the result of presence or absence of radio waves in the second frequency band is combined with the activation signal. The communication system according to claim 1 or 2, wherein the second transmitter of the first communication device transmits the radio wave in the third frequency band. The second communication device receives a response signal for the activation signal when the activation signal transmitted from the first communication device is received by the second receiver of the second communication device with a radio wave of the third frequency band. Transmitting from the first transmitter by radio waves in the second frequency band,
Before transmitting the response signal, the presence or absence of radio waves in the first frequency band is confirmed by the first receiver of the second communication device, and the result of presence or absence of radio waves in the first frequency band is combined with the response signal. The communication system according to claim 3, wherein transmission is performed by radio waves in the second frequency band from the first transmitter of the second communication device. The unauthorized communication is determined by measuring a propagation distance in mutual communication between the first communication device and the second communication device using the first frequency band and the second frequency band. The communication system as described in any one. A radio wave in a first frequency band, a radio wave in a second frequency band that is a frequency band different from the first frequency band, and a radio wave in a third frequency band that is a frequency band different from the first frequency band and the second frequency band. A communication system in which the first communication device and the second communication device communicate with each other using radio waves in three frequency bands,
The first communication device includes a first transmitter that transmits radio waves in the first frequency band, a first receiver that receives radio waves in the second frequency band, and a first transmitter that transmits radio waves in the third frequency band. 2 transmitters,
The second communication device includes a first receiver that receives radio waves in the first frequency band, a first transmitter that transmits radio waves in the second frequency band, and a first receiver that receives radio waves in the third frequency band. 2 receivers,
The second communication device confirms the presence / absence of radio waves in the first frequency band by the first receiver of the second communication device, and obtains the result of presence / absence of radio waves in the first frequency band of the second communication device. Transmitting from the first transmitter by radio waves in the second frequency band,
The first communication device transmits a radio wave of the first frequency band by the first transmitter of the first communication device when receiving a result of no radio wave of the first frequency band. The first frequency band is a frequency band that requires an interference avoidance function for confirming whether radio waves are present in the frequency band to be used,
The second frequency band is a frequency band that does not require the interference avoidance function,
The communication system according to claim 6, wherein the third frequency band is a frequency band that does not require the interference avoidance function. By measuring the propagation distance in the mutual communication between the first communication device and the second communication device using the first frequency band and one of the second frequency band and the third frequency band. The communication system according to claim 6 or 7, wherein unauthorized communication is determined.