JP2018038025A - Wireless communication correctness determination system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless communication correctness determination system capable of discouraging illegal establishment of wireless communication that uses a relay.SOLUTION: Communication is made between a vehicle 1 and an electronic key 2 with UHF electric wave of the same frequency band. The electronic key 2 calculates a reception signal intensity of the electric wave from the vehicle 1, and the reception signal intensity is transmitted to the vehicle 1 as a reception signal intensity information 30. At the vehicle 1, a difference between the reception signal intensity information 30 being notified and a reception signal intensity of the electric wave containing the reception signal intensity information 30 is calculated, and by confirming whether or not the difference is within a reference range, communication correctness of smart communication is determined.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless communication correctness determination system in which a communication terminal and a communication master communicate wirelessly.

  2. Description of the Related Art Conventionally, many vehicles are equipped with an electronic key system (see, for example, Patent Document 1) that performs ID collation using an electronic key that transmits an ID code wirelessly (also referred to as a portable device from the possession mode). In this type of electronic key system, when an electronic key receives a request transmitted from a vehicle, the electronic key automatically returns an ID code to the vehicle in response to the request, and performs an ID verification. There is. In the key operation free system, door locking / unlocking is permitted or executed when ID verification is established outside the vehicle, and engine start operation is permitted when ID verification is established inside the vehicle.

  In such an electronic key system, a fraudulent act using a relay device (referred to as a fraudulent act using a repeater: see Patent Document 2, Patent Document 3, etc.) as a fraudulent act intended to establish ID verification without depending on the user's will There is. 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.

  In Patent Document 2, when both the RSSI (reception signal strength) of the LF signal from the vehicle to the portable device and the RSSI of the RF signal from the portable device to the vehicle are detected, and one of them is extremely small from the correlation between both RSSIs When the criteria for fraudulent use of the repeater is satisfied, door locking / unlocking and engine starting are not permitted.

  In Patent Document 3, when a vehicle transmits a plurality of radio waves, the transmission signal strength is changed and each radio wave is transmitted. When the electronic key receives a radio wave from the vehicle, the received signal strength of the received radio wave is set in the electronic key. I am trying to calculate. Then, based on the calculated received signal strength, it is determined whether or not the communication is regular communication.

JP 2005-262915 A JP 2012-60482 A JP 2011-229061 A

  By the way, conventionally, when performing communication with the LF signal from the vehicle to the electronic key and communication with the RF signal from the electronic key to the vehicle, either of them may be null in the antenna direction. Since it is erroneously determined that there has been a fraudulent act of using the repeater, door locking / unlocking and engine starting cannot be performed normally. For this reason, it is necessary to consider the relative difference between the LF signal and the RF signal. As a result, the criteria for determining that the repeater use fraud has been loosened, and the repeater use fraud may not be detected.

  An object of the present invention is to provide a wireless communication correct / incorrect determination system that can prevent the occurrence of unauthorized wireless communication using a repeater.

  In order to solve the above problem, the wireless communication correctness determination system of the present invention includes a first communication unit including a first transmission execution unit and a second communication unit including a second transmission execution unit, The transmission execution means and the second transmission execution means are wireless communication correctness determination systems capable of executing bidirectional communication by radio wave communication in the same frequency band, wherein the first communication unit is connected to the second communication unit. 1st received signal strength calculating means for calculating the received signal strength of the radio wave (hereinafter referred to as the first received signal strength), the first transmission executing means transmits information on the first received signal strength, The second communication unit, when receiving a radio wave from the first communication unit, a second received signal strength calculating means for calculating a received signal strength of the radio wave (hereinafter referred to as a second received signal strength); 1 received signal strength and second received signal strength And a communication correctness determining means for determining whether or not communication with the first communication unit is regular communication based on a comparison result between the determination value and a reference range. It is a thing.

  According to this configuration, since bidirectional communication between the second communication unit and the first communication unit is performed in the same frequency band, regardless of the antenna directivity and the distance between the second communication unit and the first communication unit, A determination value based on the first received signal strength (radio wave strength) and the second received signal strength (radio wave strength) falls within the reference range. On the other hand, when communication is performed between the second communication unit and the first communication unit via a relay (repeater), the determination value based on the first received signal strength and the second received signal strength is a reference range. Not inside. Therefore, it is possible to determine whether or not the normal communication is performed by comparing the determination value based on the first received signal strength and the second received signal strength with the reference range.

Further, the calculating means may calculate a difference between the first received signal strength and the second received signal strength as the determination value.
According to this configuration, since the determination value is the difference between the first received signal strength and the second received signal strength, it is possible to quickly determine whether the communication is normal communication with a simple calculation.

The calculating means may calculate the degree of coincidence between the time change of the first received signal strength and the time change of the second received signal strength as the determination value.
According to this configuration, even if the positional relationship between the second communication unit and the first communication unit or the propagation environment of the radio wave changes, it is possible to detect repeater use fraud.

  A plurality of antennas connected to at least one of the first communication unit and the second communication unit and used for bidirectional communication between the first communication unit and the second communication unit; And a switching unit that switches an antenna used for bidirectional communication between the plurality of antennas.

  According to this configuration, the switching unit switches between the plurality of antennas during the bidirectional communication between the first communication unit and the second communication unit, so that the first communication unit and the second communication unit are switched. Change the propagation path between. In this regard, when communication is performed between the first communication unit and the second communication unit without using a repeater, the time change of the first received signal strength and the time change of the second received signal strength are changed. Match. On the other hand, when communication is performed between the first communication unit and the second communication unit via the repeater, the time change of the first received signal strength does not match the time change of the second received signal strength. Thereby, it can be determined whether it is regular communication based on whether the time change of the 1st received signal strength and the time change of the 2nd received signal strength correspond.

  An antenna connected to at least one of the first communication unit and the second communication unit and used for bidirectional communication between the first communication unit and the second communication unit, and during bidirectional communication And a switching unit that switches the directivity of the antenna used for bidirectional communication.

  According to this configuration, the switching unit switches between the first communication unit and the second communication unit by switching the directivity of the antenna during bidirectional communication between the first communication unit and the second communication unit. The propagation path of is changed. Thereby, it can be determined whether it is regular communication based on whether the time change of the 1st received signal strength and the time change of the 2nd received signal strength correspond.

In addition, the communication correctness determination unit may determine that the communication is not normal when there are a plurality of times when the comparison result between the determination value and the reference range indicates that the communication is not normal.
According to this configuration, if there is a repeater use fraud, the comparison result between the determination value based on the first received signal strength and the second received signal strength and the reference range indicates that the repeater use is fraudulent. Since there are many cases where the number of times is different, it can be determined that the communication is not regular communication when the number of times differs.

  The first communication unit includes first comparison means for comparing the first received signal strength with a first threshold value for detecting a received signal strength saturation, and the first received signal strength is less than the first threshold value. If exceeded, the first transmission execution means transmits a first attenuation request to the second communication unit, and the second transmission execution means determines that the transmission output is the previous time based on the first attenuation request. The power control is performed so that the output is attenuated from the output and the radio wave is transmitted to the first communication unit, and the calculation unit is transmitted from the first communication unit after the transmission output is attenuated and the radio wave is transmitted, The determination value may be calculated based on the second received signal strength of the radio wave without the first attenuation request and the new first received signal strength notified by the radio wave for which the second received signal strength is calculated. Good.

  According to this configuration, if the first communication unit and the second communication unit are close to each other and the first received signal strength may exceed the first threshold value for detecting the received signal strength saturation, the first received signal strength is Suppose that it is saturated.

  In this case, since the first attenuation request is sent from the first communication unit to the second communication unit, the second communication unit powers the transmission output to be attenuated from the previous output based on the first attenuation request. Control is performed and radio waves are transmitted to the first communication unit. Then, the calculation means of the second communication unit attenuates the transmission output and transmits the radio wave, and then the second received signal strength of the radio wave transmitted from the first communication unit and the radio wave from which the second received signal strength is calculated. The determination value is calculated based on the new first received signal strength notified in (1). Accordingly, the communication correctness determination unit can determine whether or not the communication is normal using a determination value based on the new first received signal strength and the second received signal strength.

  The second communication unit includes a second comparison unit that compares the second received signal strength with a second threshold value for detecting a received signal strength saturation, and the second received signal strength is less than the second threshold value. If it exceeds, the second transmission execution means transmits a second attenuation request to the first communication unit, and the first transmission execution means determines that the transmission output is the previous time based on the second attenuation request. The power is controlled so as to be attenuated from the output, and radio waves are transmitted to the second communication unit, and the calculation means is transmitted from the first communication unit after transmitting the second attenuation request, and The determination value is calculated based on the new second received signal strength of the radio wave that does not require attenuation request and the first received signal strength notified by the radio wave for which the new second received signal strength is calculated. Also good.

  According to this configuration, when the first communication unit and the second communication unit are close to each other and the second received signal strength may exceed the second threshold value for detecting the received signal strength saturation, the second received signal strength is Suppose that it is saturated.

  In this case, since the second attenuation request is sent from the second communication unit to the first communication unit, the first communication unit powers the transmission output to be attenuated from the previous output based on the second attenuation request. Control is performed to transmit radio waves to the second communication unit. Then, the calculation means of the second communication unit transmits a second second received signal strength of a radio wave transmitted from the first communication unit after transmitting the second attenuation request and does not require the second attenuation request, and the new A determination value is calculated based on the first received signal strength notified by the radio wave for which the second received signal strength is calculated. Thereby, the communication correctness determination unit can determine whether or not the communication is normal using a determination value based on the first received signal strength and the new second received signal strength.

  In order to solve the above problem, the wireless communication correctness determination system of the present invention includes a first communication unit including a first transmission execution unit and a second communication unit including a second transmission execution unit, The transmission execution means and the second transmission execution means are wireless communication correctness determination systems capable of executing bidirectional communication by radio wave communication in the same frequency band, wherein the first communication unit is connected to the second communication unit. 1st received signal strength calculating means for calculating the received signal strength of the radio wave (hereinafter referred to as the first received signal strength), the first transmission executing means transmits information on the first received signal strength, The second communication unit, when receiving a radio wave from the first communication unit, a second received signal strength calculating means for calculating a received signal strength of the radio wave (hereinafter referred to as a second received signal strength); The time variation of the received signal strength and the second received signal strength Based on the result of comparison between the determination value and the reference range, it is determined whether or not the communication with the first communication unit is a normal communication based on a calculation unit that calculates a determination value indicating the degree of coincidence with the temporal change in signal strength. Communication correctness determination means, wherein the first reception signal strength calculation means calculates a first reception signal strength associated with a reception time each time a radio wave is received from the second communication unit, and A communication part transmits the information of the 1st received signal strength of a some reception opportunity collectively by the said 1st transmission execution means.

  According to this configuration, since bidirectional communication between the second communication unit and the first communication unit is performed in the same frequency band, regardless of the antenna directivity and the distance between the second communication unit and the first communication unit, Further, even if the positional relationship between the second communication unit and the first communication unit or the propagation environment of the radio wave changes, the time change of the first received signal strength (radio wave strength) and the time of the second received signal strength (radio wave strength). The determination value indicating the degree of coincidence with the change is within the reference range. On the other hand, when communication is performed between the second communication unit and the first communication unit via a relay (repeater), the time change of the first received signal strength and the time change of the second received signal strength The judgment value indicating the degree of coincidence does not fall within the reference range. Therefore, it is possible to determine whether or not the normal communication is performed by comparing the determination value indicating the degree of coincidence between the time change of the first received signal strength and the time change of the second received signal strength with the reference range.

  In addition, since the information on the first received signal strength of a plurality of reception opportunities is transmitted together, the information on the first received signal strength of the received radio wave is transmitted each time a radio wave is received from the second communication unit. As compared with the above, when transmitting a response radio wave to the radio wave from the second communication unit, each response radio wave can be simplified.

  In addition, every time a radio wave is received from the second communication unit, unlike the case where the first received signal strength information of the received radio wave is transmitted, the second communication unit receives the first received signal strength information. As such, there is no inconvenience that the next radio wave cannot be transmitted until this is done, so that bidirectional communication can be performed smoothly.

  ADVANTAGE OF THE INVENTION According to this invention, it can be made hard to produce fraudulent establishment of radio | wireless communication using a repeater.

The block diagram which shows the structure of the communication fraud establishment prevention system of 1st Embodiment. The timing chart which shows the communication sequence of smart communication. Explanatory drawing which shows the outline | summary of the unauthorized communication using a repeater. The flowchart of the right-and-left determination of the radio | wireless communication of the radio | wireless communication correctness determination system in smart communication. Explanatory drawing of the path | route in the radio | wireless communication between a vehicle and an electronic key. Explanatory drawing of the path | route in the radio | wireless communication between the vehicle and electronic key in the case of a one-sided relay. The block diagram which shows the structure of the communication fraud establishment prevention system of 2nd Embodiment. The block diagram which shows the structure of the communication fraud establishment prevention system of 3rd Embodiment. The block diagram which shows the structure of the communication fraud establishment prevention system of 4th Embodiment. 10 is a flowchart of wireless communication correctness determination in the wireless communication correctness determination system in smart communication according to the fifth embodiment. The graph which shows the time change of the 1st received signal strength, and the time change of the 2nd received signal strength. The block diagram which shows the structure of the communication fraud establishment prevention system of 6th Embodiment. The flowchart of the right / no-go determination of the radio | wireless communication of the radio | wireless communication correctness determination system in the smart communication in 6th Embodiment. (A), (b) is explanatory drawing of the path | route in the radio | wireless communication between the vehicle and electronic key in 6th Embodiment. (A), (b) is a graph which shows the time change of the 1st received signal strength and the time change of the 2nd received signal strength in 6th Embodiment. (A)-(c) is a block diagram which shows schematic structure of the switch part in other embodiment.

(First embodiment)
A first embodiment of a communication fraud prevention system embodying the present invention will be described below with reference to FIGS.

  As shown in FIG. 1, the vehicle 1 transmits a wireless inquiry (request signal Srq) from the vehicle 1 to the electronic key 2, and performs ID verification based on a response (ID signal Sid) of the electronic key 2 to this inquiry. A key operation free system 3 is installed. The key operation free system 3 includes an entry function in which door lock locking / unlocking is permitted or executed when ID verification is established outside the vehicle, and a power transition operation of the vehicle 1 and the engine by the engine switch 4 in the vehicle when ID verification is established in the vehicle. There is an engine start function in which the start operation is permitted. The electronic key 2 is an example of a communication terminal and corresponds to the first communication unit, the request signal Srq corresponds to an inquiry, and the ID signal Sid corresponds to a response.

  In this case, the vehicle 1 includes a key verification device 5 that performs ID verification with the electronic key 2, a door lock device 6 that manages a door lock operation, and an engine start device 7 that manages the operation of the engine. These are provided and connected by an in-vehicle bus 8. The key verification device 5 is provided with a verification ECU (Electronic Control Unit) 9 as a control unit of the key verification device 5. In the memory (not shown) of the verification ECU 9, the ID code of the electronic key 2 that forms a pair with the vehicle 1 is registered. The verification ECU 9 is an example of a communication master and corresponds to the second communication unit.

  The verification ECU 9 transmits an LF (Low Frequency) band radio wave outside and inside the vehicle, and transmits an UHF (Ultra High Frequency) band radio wave outside and inside the vehicle and receives the UHF band radio wave. A UHF transceiver 12 is connected.

The UHF transmitter / receiver 12 transmits a request signal Srq as an ID reply request to the electronic key 2 by a radio wave in the UHF band, and attempts to establish so-called smart communication.
On the other hand, the electronic key 2 is provided with a key control unit 13 that performs overall control of the operation of the electronic key 2. An “ID code” is registered in the memory (not shown) of the key control unit 13 as an ID unique to the key. The key control unit 13 includes an LF receiver 14 that can receive LF band radio waves, a UHF band that can receive UHF band radio waves and that has the same frequency band as the UHF band radio waves transmitted from the key verification device 5. Is connected to a UHF transmitter / receiver 15 capable of transmitting the radio wave.

  As shown in FIG. 2, when the vehicle is parked, an LF band wake signal 16 is intermittently transmitted from the LF transmitter 11, and the wake signal 16 is received by the electronic key 2 so that smart communication outside the vehicle (external communication) is performed. When established, an ACK signal 17 in the UHF band is returned from the electronic key 2.

  When the verification ECU 9 receives the ACK signal 17 after transmitting the wake signal 16, it subsequently transmits a “vehicle ID 18” in the UHF band. “Vehicle ID 18” is a unique ID of the vehicle 1. When receiving the “vehicle ID 18”, the electronic key 2 performs vehicle ID collation. When the electronic key 2 confirms that the vehicle ID collation is established, the electronic key 2 returns the UHF band acknowledgment signal 19 again.

  When the verification ECU 9 receives the ACK signal 19 after transmitting the “vehicle ID 18”, the verification ECU 9 subsequently transmits a challenge 20. The challenge 20 includes a “challenge code” and a “key number”. The challenge 20 corresponds to the request signal Srq.

  When the electronic key 2 receives the challenge 20, it first performs a key number collation, and if it is confirmed that the collation is established, it passes the “challenge code” through its own encryption key and calculates a “response code”. Then, the electronic key 2 transmits a response 21 having the “response code” and the “ID code” as main data. Here, the response 21 corresponds to the ID signal Sid.

  When the verification ECU 9 transmits the challenge 20 to the electronic key 2, the verification ECU 9 also calculates a “response code” through the challenge code using its own encryption key. When the verification ECU 9 receives the response 21 from the electronic key 2, the verification ECU 9 performs response verification for confirming whether the “response code” is correct and ID code verification for confirming whether the “ID code” of the electronic key 2 is correct. When the verification ECU 9 confirms that both verifications have been established, in principle, the verification ECU 9 processes smart verification (external vehicle verification) as successful, and permits or executes door lock locking / unlocking by the door lock device 6.

  Further, when it is detected by a courtesy switch or the like that the driver has boarded, for example, transmission of the LF band wake signal 16 from the LF transmitter 11 to the inside of the vehicle is started, and smart communication ( Car communication) is executed. Then, whether or not smart verification (in-vehicle verification) is established in the vehicle is confirmed by the same procedure as that in the vehicle verification, and when the verification in the vehicle is confirmed, power supply transition operation and engine start operation by the engine starting device 7 are permitted. .

  In the case of the present embodiment, as shown in FIG. 1, the key operation free system 3 is provided with a communication fraud establishment prevention system 23 for preventing the smart communication fraud establishment using the repeater 22 shown in FIG. . The establishment of unauthorized communication using the repeater 22 means that when a user who possesses the electronic key 2 is far away from the vehicle 1, a third party who attempts the theft relays radio waves using the repeater 22, This is an act of illegally establishing communication (an illegal act using a repeater). The unauthorized communication establishment prevention system 23 of this embodiment is for preventing the establishment of unauthorized communication using the repeater 22.

  By the way, in this kind of repeater 22, although the data content can be relayed, there is the present situation that cannot be relayed (copied) to the radio wave intensity. Therefore, if the received signal strength indication (RSSI) is confirmed in the electronic key 2, whether smart communication is regular communication via the electronic key 2 or unauthorized communication using the repeater 22. I understand. For this reason, the communication fraud establishment prevention system 23 according to the present embodiment executes the communication correctness determination of the smart communication by confirming the received signal strength of the radio wave in the electronic key 2.

  In this case, as shown in FIG. 1, the key control unit 13 of the electronic key 2 has a received signal strength calculating unit 26 that calculates the received signal strength of the received radio wave when the radio wave in the UHF band is received from the verification ECU 9. Is provided. The received signal strength calculating unit 26 calculates the first received signal strength RSSI1 by detecting the amplitude of the received radio wave when the UHF transceiver 15 receives the radio wave. The received signal strength calculation unit 26 corresponds to first received signal strength calculation means.

The key control unit 13 of the electronic key 2 is provided with a reception signal strength notification unit 27 that notifies the vehicle 1 of the first reception signal strength RSSI1 calculated by the reception signal strength calculation unit 26.
When the electronic key 2 transmits various radio waves (hereinafter collectively referred to as the UHF radio wave 28) in response to the inquiry of the vehicle 1, the received signal strength notification unit 27, in addition to the main data 29 of the UHF radio wave 28, The received signal strength information 30 is put on the UHF radio wave 28 as data representing the first received signal strength RSSI1 of the received radio wave. In this embodiment, the main data 29 is the “ID code” and the “response code”. The reception signal strength notification unit 27 corresponds to a first transmission execution unit.

  On the other hand, as shown in FIG. 1, when the vehicle 1 transmits various radio waves in the UHF band (hereinafter collectively referred to as UHF radio wave 24) to the electronic key 2 during smart communication, the verification ECU 9 transmits this UHF radio wave. A transmission processing unit 25 for transmitting 24 in the same frequency band is provided. The transmission processing unit 25 corresponds to a second transmission execution unit.

  In addition, the verification ECU 9 is provided with a received signal strength calculation unit 9a that calculates a second received signal strength RSSI2 that is a received signal strength of the received radio wave when a UHF band radio wave is received from the electronic key 2. . The received signal strength calculator 9a corresponds to a second received signal strength calculator.

  Also, the verification ECU 9 receives the received signal strength information 30 (first received signal strength RSSI1) notified by the radio wave in the UHF band from the electronic key 2 and the second received signal when the received signal strength information 30 is received. A calculating unit 9b that calculates a difference from the received signal strength RSSI2 is provided. The calculation unit 9b corresponds to calculation means.

  The verification ECU 9 is provided with a communication correctness determination unit 31. The communication correctness determination unit 31 compares the difference with a reference value R registered in advance, and determines whether smart communication with the electronic key 2 is regular communication based on the comparison result. The communication correctness determination unit 31 corresponds to a communication correctness determination unit, and the difference corresponds to a determination value.

(Regarding reference value R)
The reference value R is registered in a memory (not shown) of the verification ECU 9 as follows.
First communication when the electronic key 2 receives a radio wave (received signal) in the UHF band from the vehicle 1 in communication when registering the “ID code” or the “encryption key” of the electronic key 2 in the verification ECU 9 The signal strength RSSI1 is calculated by the received signal strength calculating unit 26, and the received signal strength notifying unit 27 notifies the vehicle 1 of the calculated first received signal strength RSSI1. At this time, the received signal strength information 30 is notified using a radio wave when notifying the “ID code” and the “encryption key”.

  The second received signal strength RSSI2 of the radio wave in the UHF band carrying the received signal strength information 30 is calculated by the received signal strength calculating unit 9a, and the first received signal strength transmitted from the electronic key 2 by the calculating unit 9b. The difference between RSSI1 and the second received signal strength RSSI2 calculated by the received signal strength calculator 9a is calculated. Using this difference as a reference value R, the verification ECU 9 registers it in a memory (not shown).

  Note that the frequency band of radio waves in the UHF band at the time of registration of the reference value R is the same frequency band as that of the smart communication. Here, when registering the “ID code” and the “encryption key” of the electronic key 2, the electronic key 2 is in a position close to the vehicle 1 or in a vehicle interior, Registered without using.

(Operation of the first embodiment)
Next, the operation of the communication fraud establishment prevention system 23 of this embodiment will be described with reference to FIGS.

  First, as shown in FIG. 4, it is assumed that the vehicle 1 performs smart communication with the electronic key 2. FIG. 4 is a flowchart of the wireless communication correctness determination in the wireless communication correctness determination system in smart communication. For convenience of explanation, the vehicle ID, the encryption key, and the key number of the vehicle 1 will be described on the premise that they are a proper combination. Further, it is assumed that the reception signal strength calculation unit 26 of the key control unit 13 in the electronic key 2 calculates the reception signal strength of the UHF radio wave 24 every time the UHF radio wave 24 is received from the vehicle 1.

  The vehicle 1 (verification ECU 9) first transmits an LF band wake signal 16 during smart communication. When the electronic key 2 receives the wake signal 16, the electronic key 2 transmits an ACK signal 17 of a radio wave in the UHF band to the vehicle 1. Next, the vehicle 1 (verification ECU 9) transmits the vehicle ID 18 using the UHF radio wave 24. The electronic key 2 that has received the vehicle ID 18 confirms the establishment of the vehicle ID collation of the vehicle ID 18 of the UHF band radio wave, and then transmits an ACK signal 19 of the UHF band radio wave to the vehicle 1. When vehicle 1 (verification ECU 9) receives ACK signal 19, it transmits challenge 20 as request signal Srq (UHF radio wave 24) carrying “challenge code” and “key number”. The electronic key 2 that has received the challenge 20 carries the main data 29 ("ID code" and "response code") and the first received signal strength RSSI1 that is the received signal strength when the challenge 20 is received. The response 21 which is 28 is transmitted to the vehicle 1. When receiving the response 21 from the electronic key 2, the verification ECU 9 of the vehicle 1 performs response verification for confirming whether the “response code” is correct and ID code verification for confirming whether the “ID code” of the electronic key 2 is correct. When the verification ECU 9 confirms that both verifications are established, the verification ECU 9 next determines whether or not the “communication condition” is satisfied in S10.

(Communication conditions)
The communication conditions are
P1crx (vehicle received power) = P1krx (electronic key received power) +
...... (1)
Whether Formula (1) is materialized.

Derivation of the communication condition will be described with reference to FIG. In FIG. 5, r is the distance between both antennas of the vehicle 1 and the electronic key 2.
When communicating from the vehicle 1 to the electronic key 2 using radio waves in the same frequency band,
Vehicle transmission power: P1ctx (dBm)
Vehicle transmit / receive antenna gain: Gc (dBm)
Propagation loss in free section: Lr (dBm)
Electronic key transmit / receive antenna gain: Gk (dBm)
Electronic key received power: P1krx (dBm)
Then,
P1ctx + Gc-Lr + Gk = P1krx (2)
The reception power P1krx of the electronic key is a value that approximates the first received signal strength RSSI1 at the electronic key.

On the other hand, when communicating from the electronic key 2 to the vehicle 1,
Electronic key transmission power: P1ktx (dBm)
Electronic key transmit / receive antenna gain: Gk (dBm)
Propagation loss in free section: Lr (dBm)
Vehicle transmit / receive antenna gain: Gc (dBm)
Vehicle received power: P1crx (dBm)
Then,
P1ktx + Gk−Lr + Gc = P1crx (3)
The received power P1crx of the vehicle is a value that approximates the second received signal strength RSSI2 at the vehicle. Here, the transmission / reception antenna gain Gc of the vehicle and the transmission / reception antenna gain Gk of the electronic key are as follows,
Gc = Gk + □ (dBm) (4)
Thus, the total power P0 at the transmitting and receiving antennas is the same P0 for both the vehicle and the electronic key,
P0 = P1ctx + Gc = P1ktx + Gk (5)
Then,
P1ctx (transmission power of vehicle) = P1ktx (transmission power of electronic key)-□
...... (6)
It becomes. □ represents the difference.

Also,
Gc = Gk + □ (dBm) (7)
so,
P1crx (vehicle received power) + Gc = P1krx (electronic key received power) + Gk
...... (8)
Then, the equation (1) is obtained.

From the above, P1ctx (transmission power of the vehicle) and P1ktx (transmission power of the electronic key) have a constant difference □ of the received signal strength between the vehicle and the electronic key when the frequency band is constant.
Therefore, if the difference □ is always constant, the formula (1) is established.

  In the present embodiment, the verification ECU 9 calculates the second received signal strength RSSI2 of the response 21 by the received signal strength calculation unit 9a in order to determine whether or not the expression (1) is satisfied, and the second of the response 21 is calculated. The calculation unit 9b calculates a difference between the received signal strength RSSI2 and the received signal strength information 30 (first received signal strength RSSI1) notified by the response 21. And the communication correctness determination part 31 determines communication correctness by comparing the reference value R and the said difference. In the present embodiment, the fact that the difference matches the reference value R corresponds to the difference being in the reference range.

  In addition, in the comparison between the reference value R and the difference □, if the reference value R and the difference □ are the same value, it may be determined that the communication is proper communication with no repeater use fraud. If □ is within the range of R−Δ ≦ □ ≦ R + Δ (that is, the reference range), it may be determined that the difference is constant, and the communication is determined to be appropriate with no repeater use fraud. Note that Δ is a value that it may be determined that there is no fraudulent use of the repeater.

  In S10 of FIG. 4, when the expression (1) is satisfied (that is, established), the verification ECU 9 determines that smart communication is regular communication and processes smart verification (external vehicle verification) as established, and S20 The door lock device 6 permits or executes door lock locking / unlocking.

  On the other hand, when radio waves are relayed by the one-side relay by the repeater 22 as shown in FIG. 6, the operation range is determined by the electronic key 2 from the vehicle 1. (1) is not satisfied. For this reason, it is possible to detect fraudulent use of the repeater.

  In FIG. 6, Gr is the antenna gain of the repeater 22, P1rtx is the transmission power of the repeater 22, and P1rrx is the received power of the repeater 22. Lx is a propagation loss due to the distance x between the repeater 22 and the vehicle 1, and Ly is a propagation loss due to the distance y between the repeater 22 and the electronic key 2.

  In addition, when radio waves are relayed by the relay 22 using a bidirectional relay, the antenna gain Gc, Gr, Gk involved in the communication from the vehicle 1 to the electronic key 2 and the communication from the electronic key 2 to the vehicle 1 are involved. If the antenna gains Gc, Gr, and Gk to be received are not equal, the difference □ of the received signal strength is not constant and does not satisfy Expression (1). That is, when relaying radio waves with such a bidirectional relay, it is difficult to create a repeater that makes the gain related to the forward path equal to the gain related to the return path. Therefore, it is possible to easily detect fraudulent use of the repeater.

  As described above, when the expression (1) is not satisfied in S10 (that is, when it is not established), the verification ECU 9 determines the smart communication as unauthorized communication, and performs the smart verification (ex-vehicle verification) in S30. Treat as unsuccessful.

  As described above, in the present embodiment, communication is performed between the vehicle 1 and the electronic key 2 using the UHF radio wave 24 and the UHF radio wave 28 in the same frequency band during smart communication. Then, the electronic key 2 calculates the first received signal strength RSSI1 when the radio wave from the vehicle 1 is received. In the electronic key 2, the calculated first received signal strength RSSI 1 is transmitted to the vehicle 1 as received signal strength information 30. The vehicle 1 calculates the second received signal strength RSSI2 of the radio wave carrying the received signal strength information 30, and calculates the difference between the received signal strength information 30 (first received signal strength RSSI1) and the calculated second received signal strength RSSI2. If the difference is the same as the reference value, the smart communication is processed as a regular communication. On the other hand, if the difference is not the same, the smart communication is processed as an unauthorized communication using the repeater 22. Therefore, since it is possible to identify unauthorized communication using the repeater 22, it is possible to prevent the unauthorized communication from being processed as established.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) The vehicle 1 and the electronic key 2 communicate with each other by UHF radio waves in the same frequency band, and the electronic key 2 calculates the first received signal strength RSSI1 of the radio waves from the vehicle 1 and receives the received signal strength. The signal strength information 30 is transmitted to the vehicle 1. Then, the vehicle 1 calculates a difference between the notified received signal strength information 30 (first received signal strength RSSI1) and the second received signal strength RSSI2 of the radio wave carrying the received signal strength information 30, and this difference is used as a reference. Whether the communication is correct or not is determined by checking whether the value is the same as the value. For this reason, since it becomes possible to distinguish whether smart communication is communication using the repeater 22, it is difficult to establish unauthorized communication using the repeater 22. Therefore, security against unauthorized use or theft of the vehicle 1 can be ensured.

  (2) Since authentication of smart communication is performed on the vehicle 1 side, it is not necessary to newly provide this kind of authentication function in the electronic key 2. Therefore, the electronic key 2 used so far can be used as it is, and the electronic key 2 can have a simple structure.

  (3) Since the determination value used for comparison with the reference value to determine whether or not regular communication is used is the difference between the first received signal strength RSSI1 and the second received signal strength RSSI2, the regular communication can be performed quickly with a simple calculation. It can be determined whether or not.

(Second Embodiment)
Next, the communication fraud establishment preventing system 23 employed in the key operation free system 3 of the second embodiment will be described with reference to FIG. In the present embodiment, the configuration different from that of the first embodiment will be mainly described, and the same or corresponding configurations as those of the first embodiment will be denoted by the same reference numerals and detailed description thereof will be omitted. In the present embodiment, as in the first embodiment, UHF radio waves used for communication between the vehicle 1 and the electronic key 2 are in the same frequency band. Moreover, the type of UHF radio wave of each embodiment including this embodiment is not limited.

In the present embodiment, the key control unit 13 of the electronic key 2 is different from the first embodiment in that a comparison unit 13a is provided.
The comparison unit 13a compares the first reception signal strength RSSI1 of the UHF radio wave transmitted from the vehicle 1 calculated by the reception signal strength calculation unit 26 with a first threshold value for detection of reception signal strength saturation. Note that the first threshold value is slightly lower than the saturation value (maximum value) of the received signal strength of UHF radio waves that can be processed by, for example, the circuit inside the UHF transceiver 15. When the first received signal strength RSSI1 exceeds the first threshold for detecting the received signal strength saturation, the comparing unit 13a determines that the first received signal strength RSSI1 of the received radio wave is saturated. When this determination is made, the reception signal strength notification unit 27 notifies the vehicle 1 of the first reception signal strength RSSI1 and the attenuation request that are saturated with UHF radio waves. If it is determined that the UHF radio wave from the vehicle 1 is saturated, the electronic key 2 is transmitted as a response to the UHF radio wave to be notified.

Here, the comparison unit 13a corresponds to a first comparison unit, and the attenuation request corresponds to a first attenuation request.
When the verification ECU 9 of the vehicle 1 receives the first received signal strength RSSI1 and the attenuation request, the transmission processing unit 25 performs power control so as to attenuate the transmission output from the previous output based on them, and the electronic key 2 Send UHF radio waves to In this case, the attenuation α of the transmission output is a preset amount.

Note that the verification ECU 9 of the vehicle 1 performs the same process as described above every time it receives the first received signal strength RSSI1 and the attenuation request.
When the calculation unit 9b receives the notification of the first received signal strength RSSI1 without the attenuation request from the electronic key 2 after the above processing, the calculation unit 9b receives the second received signal of the radio wave itself without the attenuation request. A difference between the strength RSSI2 and the new first received signal strength RSSI1 notified by the radio wave is calculated.

  In this case, the communication correctness determination unit 31 determines the reference value changed from “R” to “R + n · α” and the difference calculated by the calculation unit 9b according to the number of times the transmission output is attenuated by the attenuation amount α. By comparing, it is determined whether the communication is correct.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) When the vehicle 1 and the electronic key 2 are close to each other, the received signal intensity of the radio wave received by the electronic key 2 may be saturated. In this case, in the present embodiment, the electronic key 2 requests the verification ECU 9 of the vehicle 1 to attenuate the transmission output of the radio wave, so that the received signal strength of the radio wave received by the electronic key 2 is not saturated. With this saturation disappearing, it is possible to determine whether the smart communication is correct or not. As a result, the same effect as the first embodiment is obtained.

(Third embodiment)
Next, the communication fraud establishment prevention system 23 employed in the key operation free system 3 of the third embodiment will be described with reference to FIG. In the present embodiment, the configuration different from that of the first embodiment will be mainly described, and the same or corresponding configurations as those of the first embodiment will be denoted by the same reference numerals and detailed description thereof will be omitted. In the present embodiment, as in the first embodiment, UHF radio waves used for communication between the vehicle 1 and the electronic key 2 are in the same frequency band.

In the present embodiment, the comparison ECU 9 of the vehicle 1 is different from the first embodiment in that a comparison unit 9c is provided.
The comparison unit 9c compares the second received signal strength RSSI2 of the UHF radio wave from the electronic key 2 calculated by the received signal strength calculating unit 9a with the second threshold value for detecting the received signal strength saturation, and compares the second received signal strength. When RSSI2 exceeds the second threshold value for detecting the received signal strength saturation, it is determined that the received signal strength of the received radio wave is saturated. Note that the second threshold value is slightly lower than the saturation value (maximum value) of the received signal strength of UHF radio waves that can be processed by, for example, the circuit inside the UHF transceiver 12.

  The transmission processing unit 25 transmits the attenuation request and the second received signal strength RSSI2 exceeding the second threshold to the electronic key 2. Here, the comparison unit 9c corresponds to a second comparison unit, and the attenuation request corresponds to a second attenuation request.

  The reception signal strength notification unit 27 of the electronic key 2 performs power control so that the transmission output is attenuated from the previous output based on the attenuation request and the second reception signal strength RSSI2 exceeding the second threshold, and the vehicle Send radio waves to 1. In this case, the attenuation β of the transmission output is a preset amount. The attenuation amount β may be the same as or different from the attenuation amount α of the second embodiment.

Every time the electronic key 2 receives the attenuation request and the second received signal strength RSSI2 exceeding the second threshold, the same process as described above is performed.
The calculation unit 9b of the verification ECU 9 of the vehicle 1 performs a challenge 20 in which the transmission processing unit 25 does not include the attenuation request immediately after or after transmitting the attenuation request and the second received signal strength RSSI2 exceeding the second threshold. The difference between the new second received signal strength RSSI2 of the radio wave itself transmitted from the electronic key 2 and the first received signal strength RSSI1 notified by the radio wave from which the new second received signal strength RSSI2 is calculated calculate. The communication correctness determination unit 31 then changes the reference value changed from “R” to “R + m · β” according to the number m of transmission output attenuation by the attenuation amount β (that is, the number of attenuation requests), and the calculation unit 9b. Is compared with the difference calculated by, to determine whether the communication is correct.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) When the vehicle 1 and the electronic key 2 are close to each other, the received signal intensity of the radio wave received by the verification ECU 9 may be saturated. In this case, in this embodiment, the verification ECU 9 requests the electronic key 2 to attenuate the transmission output of the radio wave, so that the received signal intensity of the radio wave received by the verification ECU 9 can be prevented from being saturated. With this saturation disappearing, it is possible to determine whether the smart communication is correct or not. As a result, the same effect as the first embodiment is obtained.

(Fourth embodiment)
Next, the communication fraud establishment preventing system 23 employed in the key operation free system 3 of the fourth embodiment will be described with reference to FIG. The fourth embodiment is a combination of the second embodiment and the third embodiment. That is, in this embodiment, as shown in FIG. 9, the key operation free system 3 and the communication fraud establishment prevention system 23 are configured by the electronic key 2 having the comparison unit 13a and the verification ECU 9 having the comparison unit 9c. . This unauthorized communication establishment prevention system 23 has the effects described in the second embodiment and the third embodiment.

  In the fourth embodiment, when n · attenuation amount α ≠ m · attenuation amount β, the communication correctness determination unit 31 determines the transmission output according to the amount of attenuation on the vehicle 1 side and the electronic key 2 side, respectively. By comparing the reference value changed from “R” to “R + n · α−m · β” with the difference calculated by the calculation unit 9b, the communication correctness is determined.

  When n · attenuation amount α = m · attenuation amount β, the communication correctness determination unit 31 sets the reference value to “R” and compares the reference value R with the difference calculated by the calculation unit 9b. Thus, the communication correctness is determined.

In addition, the said 1st-4th embodiment is not restricted to the structure described so far, You may change into the following aspects.
In each of the above embodiments, the received signal strength information 30 is put on the response 21, but in the UHF radio wave 28 transmitted from the electronic key 2, the radio wave on which the received signal strength information 30 is put is the ACK signals 17 and 19, the response 21 may be used, and other types of UHF radio waves may be used. Then, the second received signal strength RSSI2 of the radio wave carrying the received signal strength information 30 is calculated by the received signal strength calculating unit 9a, the difference is calculated by the calculating unit 9b, and then the communication correctness determining unit 31 calculates the reference value R and The difference □ may be compared.

  In each of the above embodiments, the received signal strength of the radio wave carrying the received signal strength information 30 is the second received signal strength RSSI2, but the received signal strength of the radio wave from the electronic key 2 not including the received signal strength information 30 is The second received signal strength RSSI2 may be used.

  In each of the above embodiments, when the difference between the second received signal strength RSSI2 of the response 21 and the first received signal strength RSSI1 (received signal strength information 30) of the challenge 20 is different from the reference value R once. , It was not regular communication.

  Instead, in the various radio wave communication between the vehicle 1 and the electronic key 2, the second received signal of the radio wave that is communicated a plurality of times and the vehicle 1 is notified of the first received signal strength RSSI1 (received signal strength information 30). Even if the difference between the strength RSSI2 and the first received signal strength RSSI1 is not the same as the reference value and the difference becomes constant after the determination by the communication correctness determination unit 31, the difference is constant. Good.

  In the second embodiment, when the UHF radio wave transmitted from the vehicle 1 is saturated, the electronic key 2 sends the attenuation request (first attenuation request) and the first received signal strength RSSI1 at that time to the vehicle 1. However, only the attenuation request (first attenuation request) may be transmitted to the vehicle 1. In this case, the transmission processing unit 25 in the verification ECU 9 of the vehicle 1 attenuates the transmission output of the UHF radio wave based on this attenuation request.

  In the third embodiment, when the UHF radio wave transmitted from the electronic key 2 is saturated, the vehicle 1 sends the attenuation request (second attenuation request) and the second received signal strength RSSI2 at that time to the electronic key 2. However, only the attenuation request (second attenuation request) may be transmitted to the electronic key 2. In this case, the reception signal strength notification unit 27 of the electronic key 2 attenuates the transmission output of the UHF radio wave based on this attenuation request.

(Fifth embodiment)
Next, a communication fraud establishment prevention system 23 employed in the key operation free system 3 of the fifth embodiment will be described with reference to FIGS. 10 and 11 with reference to FIG. In the present embodiment, as in the first embodiment, UHF radio waves used for communication between the vehicle 1 and the electronic key 2 are in the same frequency band.

  In this embodiment, instead of the difference between the first received signal strength RSSI1 and the second received signal strength RSSI2, the degree of coincidence between the time change of the first received signal strength and the time change of the second received signal strength is used as the determination value. However, this is different from the first embodiment.

  As shown in FIG. 10, it is assumed that the vehicle 1 performs smart communication with the electronic key 2. The reception signal strength calculation unit 26 of the key control unit 13 in the electronic key 2 associates the first reception signal strength of the UHF radio wave 24 with the reception time each time the UHF radio wave 24 is received from the vehicle 1. Assume that it is calculated. Therefore, the received signal strength calculation unit 26 corresponds to first received signal strength calculation means. Further, every time the UHF radio wave 28 is received from the electronic key 2, the received signal strength calculation unit 9 a of the verification ECU 9 in the vehicle 1 calculates the second received signal intensity of the UHF radio wave 28 in association with the reception time. It shall be. Therefore, the received signal strength calculating unit 9a corresponds to a second received signal strength calculating unit. As a result, in both the vehicle 1 and the electronic key 2, a temporal change in the received signal strength of the UHF radio wave from the other party can be obtained.

  The vehicle 1 (verification ECU 9) first transmits a wake signal of an LF band radio wave during smart communication. When the electronic key 2 receives the wake signal, the electronic key 2 transmits an UHF band radio wave ACK signal to the vehicle 1.

  Thereafter, the vehicle 1 (verification ECU 9) transmits the first challenge by the UHF radio wave 24. The electronic key 2 that has received the first challenge is calculated by associating the first received signal strength RSSIkey1 (referred to as B1 for convenience) when the first challenge is received with the reception time of the first challenge, In this example, the first response, which is the UHF radio wave 28 not including the first received signal strength RSSIkey1, is transmitted to the vehicle 1. When the first response is received, the verification ECU 9 of the vehicle 1 calculates the second received signal strength RSSIcar1 (referred to as A1 for convenience) when the first response is received in association with the first response reception time. Above, the second challenge by UHF radio wave 24 is transmitted.

  The electronic key 2 that has received the second challenge is calculated by associating the first received signal strength RSSIkey2 (referred to as B2 for convenience) when receiving the second challenge with the reception time of the second challenge, In this example, a second response that is a UHF radio wave 28 not including the first received signal strength RSSIkey2 is transmitted to the vehicle 1. When the second response is received, the verification ECU 9 of the vehicle 1 calculates the second received signal strength RSSIcar2 (referred to as A2 for convenience) when the second response is received, in association with the second response reception time. Above, a third challenge (not shown) by the UHF radio wave 24 is transmitted.

  Eventually, the electronic key 2 that has received the n-th challenge is calculated by associating the first received signal strength RSSIkeyn (referred to as Bn for convenience) when the n-th challenge is received with the reception time of the n-th challenge. Thus, in this example, the nth response, which is the UHF radio wave 28 not including the first received signal strength RSSIkeyn, is transmitted to the vehicle 1. When the verification ECU 9 of the vehicle 1 receives the n-th response, the verification ECU 9 calculates the second received signal strength RSSIcarn (referred to as An for convenience) at the time of receiving the n-th response in association with the reception time of the n-th response. .

  The electronic key 2 transmits the n-th response to the vehicle 1 after the transmission and reception of the challenge and response between the vehicle 1 and the electronic key 2 are repeated n times. The UHF radio wave 28 carrying the first received signal strength information RSSIkeym including all of B1 to Bn is transmitted to the vehicle 1.

  In S40, the verification ECU 9 of the vehicle 1 calculates a correlation coefficient ρ (−1 ≦ ρ ≦ 1) indicating the degree of coincidence between the time change of the first received signal strength and the time change of the second received signal strength. The correlation coefficient ρ corresponds to a determination value, and the calculation unit 9b of the verification ECU 9 corresponds to a calculation unit. Here, the second received signal strength measured by the vehicle 1 is A = [A1, A2,..., An], and the first received signal strength measured by the electronic key 2 is B = [B1, B2,. .., Bn]. In FIG. 11, the second received signal strength measured by the vehicle 1 is plotted with a mark “x”, and the first received signal strength measured with the electronic key 2 is plotted with a mark “◯”. Time change is shown.

  Returning to the calculation of the correlation coefficient ρ, the average value of the second received signal strength is a = ΣAm / n (where m = 1, 2,..., N), and the average value of the first received signal strength is b. = ΣBm / n (where m = 1, 2,..., N). Then, the difference between the second received signal strength and its average value is A ′ = [A1-a, A2-a,..., An−a], and the difference between the first received signal strength and its average value is B ′ = [B1-b, B2-b,..., Bn-b].

  The Pearson correlation coefficient ρ is calculated using the following equation (9) (S40).

車両１の照合ＥＣＵ９は、Ｓ５０において、相関係数ρが１に近いか否かを判断する。相関係数ρが１に近いほど相関が高く、第１受信信号強度の時間変化と第２受信信号強度の時間変化とがおよそ一致して相似形となっていることになる。逆に、相関係数ρが０に近いほど相関がなく、双方の時間変化が相似形からかけ離れていることになる。この１に近い値（一例として０．９５）から１までの範囲が「基準範囲」に相当し、Ｓ５０では、相関係数ρが０．９５≦ρ≦１であるか否かが判断される。

The verification ECU 9 of the vehicle 1 determines whether or not the correlation coefficient ρ is close to 1 in S50. The closer the correlation coefficient ρ is to 1, the higher the correlation is, and the time change of the first received signal strength and the time change of the second received signal strength are approximately the same and have a similar shape. On the contrary, the closer the correlation coefficient ρ is to 0, the less the correlation is, and the time changes of both are far from the similar shape. A range from a value close to 1 (0.95 as an example) to 1 corresponds to a “reference range”, and in S50, it is determined whether or not the correlation coefficient ρ is 0.95 ≦ ρ ≦ 1. .

  If the verification ECU 9 of the vehicle 1 determines YES in S50, it permits or executes door lock locking / unlocking in S60, whereas if it determines NO in S50, it performs smart verification while detecting repeater use fraud in S70 ( (External vehicle verification) is processed as not established. The communication correctness determination unit 31 of the verification ECU 9 corresponds to communication correctness determination means.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) Since the two-way communication between the verification ECU 9 of the vehicle 1 and the electronic key 2 is performed using UHF radio waves in the same frequency band, the position between the two is not dependent on the antenna directivity or the distance between the two. Even if the relationship or radio wave propagation environment changes, the determination value indicating the degree of coincidence between the time change of the first received signal strength and the time change of the second received signal strength is within the reference range. On the other hand, when communication is performed between the verification ECU 9 and the electronic key 2 via the repeater 22, the degree of coincidence between the time change of the first received signal strength and the time change of the second received signal strength is determined. The judgment value shown does not fall within the reference range. Therefore, it is possible to determine whether or not the normal communication is performed by comparing the correlation coefficient ρ, which is a determination value indicating the degree of coincidence between the time change of the first received signal strength and the time change of the second received signal strength, with the reference range. it can. As a result, it is possible to distinguish whether the smart communication is a communication using the repeater 22, so that it is difficult to establish an unauthorized communication using the repeater 22. Therefore, security against unauthorized use or theft of the vehicle 1 can be ensured.

  (2) When information on the first received signal strength of a plurality of reception opportunities is transmitted together, information on the first received signal strength of the received radio waves is transmitted each time a radio wave from the verification ECU 9 is received. In comparison, each response radio wave can be simplified when the response radio wave from the verification ECU 9 is transmitted.

  (3) Unlike the case where the information on the first received signal strength of the received radio wave is transmitted each time the radio wave from the verification ECU 9 is received, the verification ECU 9 continues until the information on the first received signal strength is received. Therefore, the two-way communication can be performed smoothly.

(4) In relation to (1) above, it is possible to detect fraudulent use of the repeater even if the user with the electronic key 2 moves.
(5) In the case of a one-sided relay by the repeater 22, it is possible to detect an illegal act of using the repeater because one of the paths is different.

(6) In the case of a bidirectional relay using a different frequency band, it is possible to detect repeater use fraud because both routes are different.
(7) Acquisition (exchange) of the first received signal strength when registering the electronic key 2 in the verification ECU 9 is not necessary.

The fifth embodiment is not limited to the configuration described so far, and may be modified as follows.
Instead of using Pearson's correlation coefficient ρ as a determination value, a cross-correlation coefficient may be used. Alternatively, the least square method, Fourier transform, wavelet transform may be used, or image processing technology (image coincidence detection, etc.) may be applied.

  Instead of transmitting the information of the first received signal strengths of a plurality of reception opportunities all together, the first received signal of the received radio wave is received every time the UHF radio wave 24 from the verification ECU 9 is received with reference to FIG. The UHF radio wave 28 carrying the strength information (received signal strength information 30) may be transmitted to the vehicle 1. In this case, the received signal strength information 30 is information on the first received signal strength associated with the reception time of the UHF radio wave 24. As a result, the verification ECU 9 of the vehicle 1 can obtain the time change of the second received signal strength while calculating the second received signal strength of the UHF radio wave 28 in association with the reception time, and is included in the UHF radio wave 28. Based on the received signal strength information 30, a time change of the first received signal strength can be obtained (similar to FIG. 11). Then, the calculation unit 9b of the verification ECU 9 receives the UHF radio wave 28 including the received signal strength information 30 (every reception opportunity), collects every plural times, or after the last n times Collectively, the correlation coefficient ρ is calculated.

(Sixth embodiment)
Next, a sixth embodiment of the communication fraud establishment prevention system 23 will be described with reference to FIGS. Also in this embodiment, UHF radio waves used for communication between the vehicle 1 and the electronic key 2 are in the same frequency band. The communication fraud establishment prevention system 23 including the key verification device 5 and the electronic key 2 is a wireless communication right / fail judgment system that prevents the smart communication fraud.

In the present embodiment, as in the fifth embodiment, the degree of coincidence between the time change of the first received signal strength RSSI1 and the time change of the second received signal strength RSSI2 is used as the determination value.
As shown in FIG. 12, the UHF transceiver 12 of the vehicle 1 includes two antennas 12a and 12b and a switching unit 12c. The UHF transmitter / receiver 12 transmits the UHF radio wave 24 to the electronic key 2 using either one of the two antennas 12a and 12b. Further, the UHF transceiver 12 receives the UHF radio wave 28 from the electronic key 2 by using one of the two antennas 12a and 12b. During the communication between the vehicle 1 and the electronic key 2, the switching unit 12c switches between the antenna 12a and the antenna 12b for an antenna that transmits and receives UHF band radio waves. In addition, it is preferable that the antennas 12a and 12b are provided in the vehicle 1 as far away as possible.

The UHF transceiver 15 of the electronic key 2 includes an antenna 15a.
As shown in FIG. 13, the vehicle 1 (collation ECU 9) first transmits a wake signal based on radio waves in the LF band during smart communication. When the electronic key 2 receives the wake signal, the electronic key 2 transmits an ACK signal based on a radio wave in the UHF band to the vehicle 1.

  Thereafter, similarly to the fifth embodiment, transmission / reception of a challenge (CH) and a response (Re) by radio waves in the UHF band is repeated n times between the verification ECU 9 of the vehicle 1 and the electronic key 2. That is, the verification ECU 9 transmits a challenge by the UHF radio wave 24 to the electronic key 2 n times, and the electronic key 2 transmits a response by the UHF radio wave 28 to the verification ECU 9 n times as a response to the challenge of n times. The electronic key 2 calculates the first received signal strengths RSSIkey1 to RSSIkeyn (referred to as B1 to Bn for convenience) of n received challenges in association with the challenge reception time. The verification ECU 9 calculates the second received signal strengths RSSIcar1 to RSSIcarn (referred to as A1 to An for convenience) of the received n responses in association with the reception time of the response.

  When transmission / reception of a challenge and a response is repeated n times between the vehicle 1 and the electronic key 2, the electronic key 2 transmits the nth response to the vehicle 1, and then includes all of the B1 to Bn. A UHF radio wave 28 carrying the received signal strength information RSSIkeym is transmitted to the vehicle 1. The vehicle 1 stores the calculated A1 to An.

  By the way, in this embodiment, while transmission / reception of a challenge and a response is repeated n times between the vehicle 1 and the electronic key 2, the switching part 12c switches the antenna which transmits / receives a UHF electric wave. As an example, transmission / reception between the vehicle 1 and the electronic key 2 is performed using the antenna 12a from the first time to the kth time (k <n). When the verification ECU 9 receives the k-th response, the switching unit 12c switches the antenna used for transmission / reception between the vehicle 1 and the electronic key 2 from the antenna 12a to the antenna 12b. Transmission / reception between the vehicle 1 and the electronic key 2 is executed using the antenna 12b from the (k + 1) th to the nth time.

  In S80, the verification ECU 9 of the vehicle 1 calculates the correlation coefficient ρ indicating the degree of coincidence between the time change of the first received signal strength and the time change of the second received signal strength by using the equation (9).

  In S90, the verification ECU 9 of the vehicle 1 determines whether or not the correlation coefficient ρ is close to 1, that is, whether or not the temporal change in the first received signal strength matches the temporal change in the second received signal strength. to decide. In particular, it is preferable to confirm the degree of coincidence between the temporal change in the first received signal strength and the temporal change in the second received signal strength in a certain period immediately after switching the antenna by the switching unit 12c. This is because immediately after the switching unit 12c switches the antenna, the first received signal strength and the second received signal strength vary greatly.

  If the verification ECU 9 of the vehicle 1 determines YES in S90, it permits the door lock device 6 to be locked / unlocked by the door lock device 6 in S100, while if NO is determined in S90, it detects an illegal act of using the repeater in S110. In-car smart verification is treated as not established.

Next, a communication path in wireless communication between the vehicle 1 and the electronic key 2 will be described. Here, it is assumed that the vehicle 1 and the electronic key 2 are stationary.
First, a comparative example will be described. As shown in FIG. 14A, a repeater 22 is provided on the communication path between the vehicle 1 and the electronic key 2. Here, the UHF radio wave transmitted from the vehicle 1 reaches the electronic key 2 via the repeater 22. Therefore, UHF radio waves transmitted from the antenna 15a of the electronic key 2 reach the vehicle 1 directly, whereas UHF radio waves transmitted from the antenna 12a of the vehicle 1 are transmitted via the antenna 22a of the repeater 22 to the electronic key 2 Reaches the antenna 15a. When the vehicle 1 and the electronic key 2 are stationary, the positional relationship and the propagation environment between the vehicle 1 and the electronic key 2 do not change. Further, even when communication between the vehicle 1 and the electronic key 2 is performed via the repeater 22, the positional relationship between the vehicle 1 and the electronic key 2 and the propagation environment as long as the repeater 22 does not move. Does not change. That is, the propagation path of the radio wave between the vehicle 1 and the electronic key 2 does not change.

  As shown in FIG. 15 (a), when the vehicle 1 and the electronic key 2 are stationary, the first received signal strength indicated by the solid line and the second received signal strength indicated by the two-dot chain line are It is constant regardless of the course. Note that the communication path from the vehicle 1 to the electronic key 2 via the repeater 22 and the communication path from the electronic key 2 to the vehicle 1 not via the repeater 22 differ in the propagation distance and propagation environment of radio waves. The first received signal strength and the second received signal strength exhibit similar time changes (trajectories) in a state where they deviate from each other by a certain amount.

  On the other hand, as shown in FIG. 14B, in this embodiment, the vehicle 1 and the electronic key 2 are in a stationary state by switching the antennas 12a and 12b provided in the vehicle 1. In addition, the propagation path of the radio wave between the vehicle 1 and the electronic key 2 can be changed. That is, the UHF radio wave transmitted from the antenna 12a reaches the antenna 15a via the antenna 22a as indicated by a solid line. Further, the UHF radio wave transmitted from the antenna 12b reaches the antenna 15a via the antenna 22a as indicated by a broken line. For this reason, the communication path to the antenna 15a differs between the antenna 12a and the antenna 12b. Thereby, although the positional relationship between the repeater 22 and the electronic key 2 does not change, the propagation path of the radio wave between the vehicle 1 and the repeater 22 is changed from the path between the antenna 12a and the antenna 22a to the antenna. It changes by the amount of switching to the path between 12b and the antenna 22a. Simply, it is considered that the closer the vehicle 1 and the repeater 22 are, the greater the received signal strength of the UHF radio wave that reaches the repeater 22 and the greater the first received signal strength calculated by the electronic key 2. In addition, while there is an obstacle between the antenna 12a and the antenna 22a that interferes with the UHF radio wave, when there is no obstacle between the antenna 12b and the antenna 22a that interferes with the UHF radio wave, the antenna 12a to the antenna By switching to 12b, the propagation environment of the UHF radio wave to the antenna 22a can be changed. As a result, the first received signal strength calculated by the electronic key 2 changes.

  Also, the communication path from the electronic key 2 to the vehicle 1 is switched from the antenna 12a to the antenna 12b, so that the propagation path of the radio wave between the vehicle 1 and the electronic key 2 changes, so that the vehicle 1 The second received signal strength calculated by the verification ECU 9 changes.

  As shown in FIG. 15 (b), when the vehicle 1 and the electronic key 2 are stationary, the first reception signal strength indicated by the solid line is also indicated by the two-dot chain line until the antenna is switched. The signal intensity is also a constant value regardless of the passage of time. For this reason, the time change of the first received signal strength matches the time change of the second received signal strength because the time change of the second received signal strength matches the time change of the second received signal strength. It is difficult to determine whether or not the communication between the vehicle 1 and the electronic key 2 is an unauthorized communication using the repeater 22 only by the degree.

  However, in the present embodiment, the vehicle 1 is switched by switching the antenna of the vehicle 1 during bidirectional communication between the vehicle 1 and the electronic key 2 (during measurement of the first received signal strength and the second received signal strength). Even when the electronic key 2 is stationary, the first received signal strength and the second received signal strength can be changed. As an example, when the antenna of the vehicle 1 is switched, the first received signal strength rapidly increases and the second received signal strength decreases rapidly. That is, the UHF radio wave is transmitted via the repeater 22 when transmitted from the vehicle 1 to the electronic key 2, while not transmitted via the repeater 22 when transmitted from the electronic key 2 to the vehicle 1. Therefore, the tendency of changes in the first received signal strength and the second received signal strength is different. For this reason, immediately after the antenna of the vehicle 1 is switched, the time change of the first received signal strength does not match the time change of the second received signal strength (there is no correlation).

When a certain amount of time elapses after the antenna of the vehicle 1 is switched, the first received signal strength and the second received signal strength again become constant values regardless of the passage of time.
According to the configuration of the present embodiment, the following effects can be obtained.

  (1) During bidirectional communication between the verification ECU 9 of the vehicle 1 and the electronic key 2, the switching unit 12c switches the antenna (for example, antenna diversity), thereby propagating radio waves between the vehicle 1 and the electronic key 2. Since the path can be changed, the first received signal strength and the second received signal strength change. When the repeater 22 is not used, even if the propagation path of the radio wave between the vehicle 1 and the electronic key 2 is changed by switching to another antenna, the time change of the first received signal strength and the (2) The time change of the received signal strength changes in a similar manner with almost the same state. In this case, the correlation coefficient ρ, which is a determination value indicating the degree of coincidence between the temporal change in the first received signal strength and the temporal change in the second received signal strength, is almost 1 (there is a correlation). This is because the communication path from the vehicle 1 to the electronic key 2 and the communication path from the electronic key 2 to the vehicle 1 are the same even when the antenna is switched.

  On the other hand, when the repeater 22 is used, the time change of the first received signal strength does not coincide with the time change of the second received signal strength by switching to another antenna. The correlation coefficient ρ, which is a determination value indicating the degree of coincidence between the time change of the signal strength and the time change of the second received signal strength, becomes small. As a result, it is possible to distinguish whether the smart communication is unauthorized communication using the repeater 22. It is possible to make it difficult to establish unauthorized communication using the repeater 22 by taking some countermeasures based on whether smart communication is unauthorized communication.

  (2) Even when the vehicle 1 and the electronic key 2 are stationary, the time change of the first received signal strength and the time change of the second received signal strength can be changed by switching the antenna. This is because the propagation path between the vehicle 1 and the electronic key 2 changes by switching to another antenna even when the vehicle 1 and the electronic key 2 are stationary. Therefore, even when the vehicle 1 and the electronic key 2 are stationary, the smart communication uses the repeater 22 based on the time change of the first received signal strength and the time change of the second received signal strength. It can be determined whether or not the communication is unauthorized.

The sixth embodiment is not limited to the configuration described so far, and may be modified as follows.
The correlation coefficient indicating the degree of coincidence between the time change of the first received signal strength and the time change of the second received signal strength is calculated based on data for a certain time immediately after the antenna is switched, and the correlation coefficient is It may be determined whether the communication between the vehicle 1 and the electronic key 2 is unauthorized communication as a determination value. Further, as a determination value, a correlation coefficient of time change of a difference between the first received signal strength and the second received signal strength may be used. Further, not only the correlation coefficient, but also any determination value may be used as long as it is a determination value for determining whether the time change of the first received signal strength and the time change of the second received signal strength are the same. Good.

Although two antennas 12a and 12b are provided in the vehicle 1, three or more antennas may be provided. In addition, it is preferable that each antenna exists in the position away from each other.
-Although the two antennas 12a and 12b were provided in the vehicle 1, it is not restricted to this. For example, the electronic key 2 may be switched between the antenna 15a and the separate antenna by providing a separate antenna instead of the antenna 15a. Further, both the vehicle 1 and the electronic key 2 may be switched between a plurality of antennas by providing a plurality of antennas.

  -The propagation environment between the vehicle 1 and the electronic key 2 is not limited to providing a plurality of antennas 12a and 12b so that the antenna can be physically switched on the vehicle 1 but by changing the directivity of the antenna. It may be changed. For example, as shown in FIG. 16A, the directivity of the antenna 12a is changed by switching the power supply 40 that supplies power to the antenna 12a to the power supply 41 that supplies power having a voltage value different from that of the power supply 40. May be. The switching unit 12c switches the power source to which the antenna 12a is connected between the power source 40 and the power source 41. Thereby, the antenna 12a is switched to an antenna in a different state. Further, the directivity of the antenna 12a may be changed by changing the capacitance or resistance value of the antenna 12a. For example, as shown in FIG. 16B, the directivity of the antenna 12 a may be changed by switching whether or not the coil 42 is interposed between the antenna 12 a and the power supply 40. Thereby, the antenna 12a is switched to an antenna in a different state. Further, as shown in FIG. 16C, the directivity of the antenna 12a may be changed by switching the feeding point between the antenna 12a and the power source 40.

-You may combine the structure according to the modification of the said 1st-4th embodiment with the said 5th Embodiment and the said 6th Embodiment.
The first to sixth embodiments are not limited to the configurations described so far, and may be modified as follows.

In each of the above embodiments, the electronic key system is not limited to the key operation free system 3, and may be an immobilizer system, for example.
In each of the above embodiments, the frequency band used for bidirectional communication is not limited to the UHF band. For example, other frequency bands such as an LF (Low Frequency) band and an HF (High Frequency) band may be used. Good. In addition, about the radio wave used for bidirectional communication between the vehicle 1 and the electronic key 2, the same frequency band has the same radio wave propagation loss at the time of each communication. The range of frequencies that can be considered to hold. The reciprocity theorem is a theorem in which the determination value based on the received signal strength of both is constant regardless of the antenna directivity and the distance between the two at the same frequency.

In each of the above embodiments, the communication master is not limited to the verification ECU 9, and may be another ECU that manages communication.
In each of the above embodiments, the communication terminal is not limited to the electronic key 2 and may be any terminal capable of wireless communication.

  In the above embodiments, the inquiry is not limited to the request signal Srq, and other signals can be employed. Further, the response is not limited to the ID signal Sid, but may be any signal that the electronic key 2 returns to the vehicle 1.

In each of the above embodiments, the communication fraud establishment prevention system 23 is not limited to being used for the vehicle 1 but can be applied to other devices and apparatuses.
In each of the above embodiments, the first communication unit is a communication terminal (electronic key 2) and the second communication unit is a communication master (verification ECU 9). Conversely, the first communication unit is a communication master (verification ECU 9). The second communication unit may be a communication terminal (electronic key 2). That is, the configuration of the verification ECU 9 of each of the embodiments that performs communication correctness determination on the electronic key 2 side may be provided on the electronic key side.

  In each of the above embodiments, either one of the first communication unit and the second communication unit performs the communication correctness determination. However, the configuration of the verification ECU 9 of each embodiment that performs the communication correctness determination is as follows. You may provide in both a 1st communication part and a 2nd communication part.

  In each of the above embodiments, various parameters calculated from the received signal strength may be used for determination by machine learning.

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 2 ... Electronic key (communication terminal, 1st communication part), 3 ... Key operation free system,
4 ... engine switch, 5 ... key verification device, 6 ... door lock device,
7 ... Engine starter, 8 ... In-vehicle bus, 9 ... Verification ECU (communication master, second communication unit),
9a: Received signal strength calculating unit (second received signal strength calculating means),
9b ... calculation part (calculation means),
9c: comparison unit (second comparison means),
11 ... LF transmitter, 12 ... UHF transceiver,
13: Key control unit, 13a: Comparison unit (first comparison means),
14 ... LF receiver, 15 ... UHF transceiver, 16 ... wake signal,
17, 19 ... Acknowledgment, 18 ... Vehicle ID, 20 ... Challenge,
21 ... Response, 22 ... Repeater,
23 ... Communication fraud prevention system,
24 ... UHF radio wave, 25 ... transmission processing unit (second transmission execution means),
26. Received signal strength calculating section (first received signal strength calculating means),
27: Received signal strength notification unit (first transmission executing means),
28 ... UHF radio wave, 29 ... main data, 30 ... received signal strength information,
31: Communication correctness determination unit (communication correctness determination means),
Srq: Request signal as an inquiry, Sid: ID signal as a response,
RSSI1 ... first received signal strength, RSSI2 ... second received signal strength.

Claims (9)

A first communication unit including a first transmission execution unit; and a second communication unit including a second transmission execution unit, wherein the first transmission execution unit and the second transmission execution unit communicate with each other in the same frequency band. A wireless communication correctness determination system capable of performing bidirectional communication at
The first communication unit includes first received signal strength calculating means for calculating received signal strength of radio waves from the second communication unit (hereinafter referred to as first received signal strength), and the first transmission executing means. To transmit the first received signal strength information,
The second communication unit is
A second received signal strength calculating means for calculating a received signal strength of the radio wave (hereinafter referred to as a second received signal strength) when receiving the radio wave from the first communication unit;
Calculating means for calculating a determination value based on the first received signal strength and the second received signal strength;
A wireless communication correctness determination system comprising: communication correctness determination means for determining whether communication with the first communication unit is normal communication based on a comparison result between the determination value and a reference range.   The wireless communication correctness determination system according to claim 1, wherein the calculation unit calculates a difference between the first received signal strength and the second received signal strength as the determination value.   2. The wireless communication correctness determination system according to claim 1, wherein the calculation unit calculates a degree of coincidence between a time change in the first received signal strength and a time change in the second received signal strength as the determination value. A plurality of antennas connected to at least one of the first communication unit and the second communication unit and used for bidirectional communication between the first communication unit and the second communication unit;
The wireless communication correctness determination system according to claim 3, further comprising: a switching unit that switches an antenna used for bidirectional communication between the plurality of antennas during bidirectional communication. An antenna connected to at least one of the first communication unit and the second communication unit and used for bidirectional communication between the first communication unit and the second communication unit;
The wireless communication correctness determination system according to claim 3, further comprising: a switching unit that switches the directivity of an antenna used for bidirectional communication during bidirectional communication.   6. The communication correctness determination unit according to any one of claims 1 to 5, wherein the communication correctness determination unit determines that the communication is not a normal communication when a comparison result between the determination value and the reference range indicates that the communication is not a normal communication a plurality of times. The wireless communication correctness determination system according to claim 1. The first communication unit includes a first comparison unit that compares the first received signal strength with a first threshold value for detecting a received signal strength saturation, and the first received signal strength exceeds the first threshold value. The first transmission execution unit transmits a first attenuation request to the second communication unit;
The second transmission execution means transmits a radio wave to the first communication unit by performing power control based on the first attenuation request so that a transmission output is attenuated from a previous output,
The calculation means attenuates the transmission output and transmits a radio wave, and then transmits from the first communication unit, the second received signal strength of the radio wave without the first attenuation request, and the second received signal strength. The wireless communication correctness determination system according to any one of claims 1 to 6, wherein the determination value is calculated based on a new first received signal intensity notified by the calculated radio wave. The second communication unit includes a second comparing unit that compares the second received signal strength with a second threshold value for detecting a received signal strength saturation, and the second received signal strength exceeds the second threshold value. The second transmission execution means transmits a second attenuation request to the first communication unit;
The first transmission execution means transmits a radio wave to the second communication unit by performing power control based on the second attenuation request so that a transmission output is attenuated from a previous output,
The calculating means transmits a second second received signal strength of a radio wave that is transmitted from the first communication unit after transmitting the second attenuation request and does not require the second attenuation request, and the new second reception. The wireless communication correctness determination system according to any one of claims 1 to 7, wherein the determination value is calculated based on a first received signal strength notified by a radio wave whose signal strength is calculated. A first communication unit including a first transmission execution unit; and a second communication unit including a second transmission execution unit, wherein the first transmission execution unit and the second transmission execution unit communicate with each other in the same frequency band. A wireless communication correctness determination system capable of performing bidirectional communication at
The first communication unit includes first received signal strength calculating means for calculating received signal strength of radio waves from the second communication unit (hereinafter referred to as first received signal strength), and the first transmission executing means. To transmit the first received signal strength information,
The second communication unit is
A second received signal strength calculating means for calculating a received signal strength of the radio wave (hereinafter referred to as a second received signal strength) when receiving the radio wave from the first communication unit;
Calculating means for calculating a determination value indicating a degree of coincidence between the time change of the first received signal strength and the time change of the second received signal strength;
Communication correct / incorrect determination means for determining whether communication with the first communication unit is regular communication based on a comparison result between the determination value and a reference range,
The first received signal strength calculating means calculates a first received signal strength associated with a reception time every time a radio wave from the second communication unit is received;
The said 1st communication part is a radio | wireless communication correctness determination system which transmits the information of the 1st received signal strength of a some reception opportunity collectively by the said 1st transmission execution means.

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