Terminal device, authentication system and authentication control method

Abstract

A terminal (100, 110) that performs an authentication sequence by means of wireless communication with an external device, the terminal comprising: a communication unit (104) configured to transmit or receive a radio signal to be used for the authentication sequence; a first measuring unit (102) configured to measure a change in radio wave strength for at least a portion of the radio signal received by the communication unit (104); a second measuring unit (103) configured to measure a change in an orientation or a position of the terminal device (100, 110); and a controller (101) which is configured to determine whether there is a correlation between a measurement result of the first measuring unit (102) and a measurement result of the second measuring unit (103), i) continue the authentication sequence if the controller determines that a correlation exists, and ii) interrupt the authentication sequence if the controller determines that there is no correlation.

Description

Background of the invention 1. Field of the invention

[0001] The present invention relates to a communication terminal (hereinafter referred to as terminal), an authentication system included in the terminal, and an authentication control method. 2. Description of the state of the art

[0002] A terminal device, such as a vehicle's electronic key, executes a series of authentication sequences by wirelessly transmitting or receiving signals to or from an onboard device. If the onboard device successfully authenticates the electronic key by executing the authentication sequences, a specified operation related to the vehicle is permitted.

[0003] JP 2017-88016 A discloses a system in which, when a motion sensor installed in a user's portable device (a terminal) detects movement of the terminal, an operation such as door unlocking is permitted based on wireless communication between the portable device and a vehicle (an in-vehicle device), and when the motion sensor does not detect the movement, the operation is prohibited. Therefore, when the user's portable device is stored and remains stationary—that is, when a determination can be made that a user is carrying the portable device, is stationary, and does not intend to operate the vehicle—operation of the vehicle is prohibited, and safety is improved.

[0004] Furthermore, DE 10 2015 109 468 A1 discloses an authorization system for vehicles, which has at least one authentication element, at least one device for locating the authentication element and at least one comparison unit, wherein the authentication element, in particular a key or a keyless-go device for a vehicle, for example an automobile, has at least one radio interface for transmitting and / or receiving at least one vehicle-generated location data signal, at least one inertial sensor element for detecting inertial data in connection with at least one movement and / or at least one acceleration, at least one inertial data interface for transmitting and / or receiving inertial data, wherein the device is provided for vehicle-mounted arrangement, in particular in or on an automobile, and wherein the device has at least one radio device for transmitting and / or receiving the location data signal,and at least one location data signal exchange interface for exchanging location signal data with the comparison unit, wherein the comparison unit has at least one receiving device for receiving the location signal data and the inertial data, and at least one computing unit for generating comparison data based on the location signal data and the inertial data. Furthermore, the disclosure also relates to a method for controlling access authorization using an authorization system. Summary of the invention

[0005] In JP 2017-88016 A, in a case where the terminal device is moving, the flow of the authentication sequences cannot be restricted if wireless communication with the on-vehicle device is possible, and a desired effect is not achieved.

[0006] The present invention has been made in view of the above problems and provides a terminal device, an authentication system, and an authentication control method that can restrict the flow of an authentication sequence based on wireless communication even when a terminal device moves.

[0007] A first aspect of the present invention relates to a terminal that executes an authentication sequence by means of wireless communication with an external device.The terminal device comprises: a communication unit configured to transmit or receive radio signals used for the authentication sequence; a first measuring unit configured to measure a change in radio wave strength for at least a part of the radio signal received by the communication unit; a second measuring unit configured to measure a change in an orientation or a position of the terminal device; and a controller configured to determine whether there is a correlation between a measurement result of the first measuring unit and a measurement result of the second measuring unit, i) continue the authentication sequence if the controller determines that there is a correlation, and ii) interrupt the authentication sequence if the controller determines that there is no correlation.

[0008] According to the first aspect of the present invention, in a case where it is highly likely that radio waves are not to be transmitted directly from a transmission source device, it is possible to interrupt the authentication sequence and impose restrictions not to perform final authentication even if the terminal device moves.

[0009] In the terminal according to the first aspect of the present invention, the communication unit may comprise a multi-axis antenna having a plurality of axes that are not parallel to each other. The first measuring unit may be configured to measure a change in radio wave strength for each axis of the multi-axis antenna.

[0010] According to the first aspect of the present invention, it is possible to obtain a change in radio wave strength as changes in a vector of each directional component and to obtain a measurement result in which a change in a relative position or a relative orientation is more accurately reflected.

[0011] In the terminal according to the first aspect of the present invention, the communication unit may comprise an antenna configured to receive a radio signal in a low frequency band (LF band) as a radio signal.

[0012] According to the first aspect of the present invention, the terminal according to the present invention can be easily applied to an electronic key receiving a low frequency signal, hereinafter also referred to as LF signal, for a prior art vehicle.

[0013] In the terminal according to the first aspect of the present invention, the second measuring unit may comprise an acceleration sensor and be configured to measure the change in orientation or position based on an output of the acceleration sensor.

[0014] According to the first aspect of the present invention, it is possible to perform accurate measurement based on acceleration or gravity acting on the terminal device.

[0015] In the terminal according to the first aspect of the present invention, the acceleration sensor may be a multi-axis acceleration sensor.

[0016] In the terminal according to the first aspect of the present invention, the terminal may be an electronic key for a vehicle.

[0017] According to the first aspect of the present invention, the terminal according to the present invention can be applied to and provided for the electronic key for a vehicle of the prior art.

[0018] In the terminal according to the first aspect of the present invention, the controller may be configured to cause the communication unit not to transmit the radio signal for the authentication sequence when the controller determines that there is no correlation.

[0019] According to the first aspect of the present invention, it is possible to interrupt the authentication sequence.

[0020] In the terminal according to the first aspect of the present invention, the controller may be configured to cause the communication unit to transmit a radio signal to instruct to interrupt the authentication sequence when the controller determines that there is no correlation.

[0021] According to the first aspect of the present invention, it is possible to interrupt the authentication sequence.

[0022] In the terminal according to the first aspect of the present invention, the communication unit may be configured to receive the radio signal transmitted at different times from a plurality of positions, and the radio signal is used for the authentication sequence. The first measuring unit may be configured to measure a change in the radio wave strength of the radio signal transmitted from each of the positions. The controller may be configured to determine, for each of the positions, whether there is a correlation between a measurement result of the first measuring unit and a measurement result of the second measuring unit, i) continue the authentication sequence if the controller determines that a correlation exists at all positions, and ii) interrupt the authentication sequence if the controller determines that there is no correlation at least at one of the positions.

[0023] According to the first aspect of the present invention, it is possible to improve the accuracy of the determination regarding the correlation.

[0024] In the terminal device according to the first aspect of the present invention, the first measuring unit may be configured to calculate a difference vector of the radio wave strength between radio signals transmitted from the respective positions. The controller may be configured to interrupt the authentication sequence if the difference vector is not within a predetermined range, regardless of the result of the correlation determination.

[0025] According to the first aspect of the present invention, in a case where it is highly likely that radio waves are not intended to be transmitted directly from a transmission source device, it is possible to interrupt the authentication sequence and impose restrictions on not performing final authentication. Even if the terminal device is stationary, the same restrictions can be imposed.

[0026] A second aspect of the invention relates to an authentication system. The authentication system comprises the terminal device described above and a vehicle having an on-board device that performs the authentication sequence by means of wireless communication with the terminal device, wherein the on-board device is the external device.

[0027] According to the second aspect of the present invention, in a case where it is highly likely that radio waves should not be transmitted directly from the on-vehicle device, it is possible to interrupt the authentication sequence, impose restrictions, not perform final authentication, and prohibit operation of the vehicle.

[0028] In the authentication system according to the second aspect of the present invention, the on-vehicle device may include an on-vehicle communication unit including a receiving antenna and a transmitting antenna and configured to transmit or receive radio signals to be used for the authentication sequence, and an on-vehicle controller that performs control such that the on-vehicle communication unit performs transmission or reception of the radio signal.

[0029] A third aspect of the invention relates to an authentication system. The authentication system comprises the terminal device described above and a vehicle having an on-board device that performs the authentication sequence by wireless communication with the terminal device, wherein the on-board device is the external device. The on-board device is configured to transmit the radio signal to be used for the authentication sequence from a plurality of positions of the vehicle.

[0030] According to the third aspect of the present invention, it is possible to improve an accuracy of determination.

[0031] In the authentication system according to the third aspect of the present invention, the on-vehicle device may include an on-vehicle communication unit that includes a receiving antenna and a plurality of transmitting antennas and is configured to transmit or receive radio signals to be used for the authentication sequence, and may include an on-vehicle controller that performs control such that the on-vehicle communication unit performs transmission and reception of the radio signal.

[0032] A fourth aspect of the present invention relates to an authentication control method executed by a terminal device that executes an authentication sequence by wireless communication with an external device. The authentication control method includes: transmitting or receiving a radio signal to be used for the authentication sequence; measuring a change in radio wave strength for at least a part of the received radio signal; measuring a change in an orientation or a position of the terminal device; and determining whether there is a correlation between a measurement result of the change in radio wave strength and a measurement result of the change in the orientation or the position, i) continuing the authentication sequence when the controller determines that the correlation exists, and ii) interrupting the authentication sequence when the controller determines that there is no correlation.

[0033] According to the fourth aspect of the present invention, in a case where it is highly likely that radio waves are not to be transmitted directly from a transmission source device even if the terminal device is moving, it is possible to interrupt the authentication sequence and impose restrictions on not performing final authentication.

[0034] According to aspects of the present invention, it is possible to provide a terminal device, an authentication system, and an authentication control method that can restrict the flow of an authentication sequence based on wireless communication even when a terminal device moves. Short description of the drawing

[0035] Features, advantages and technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, wherein like reference numerals designate like elements and: Fig. 1 is a functional block diagram of an authentication system according to a first embodiment of the present invention; Fig. 2 is a schematic diagram illustrating some magnetic lines of force of a radio signal transmitted from a transmission antenna included in a vehicle according to the first embodiment of the present invention; Fig. 3 is a process flow diagram of an electronic key system according to the first embodiment of the present invention; Fig. 4 is a functional block diagram of an authentication system according to a second embodiment of the present invention; and Fig. 5 is a schematic diagram illustrating some magnetic lines of force of a radio signal transmitted from a transmission antenna included in a vehicle according to the second embodiment of the invention. Detailed description of embodimentsOverview

[0036] In an authentication system according to embodiments of the present invention, a terminal device and an on-board device of a stationary vehicle perform a predetermined authentication sequence via wireless communication. The terminal device measures a change in a radio wave strength of a radio signal and a change in an orientation or position of the terminal device itself. A determination is made as to whether a constant correlation exists between measurement results of the two changes described above. If a determination is made that the correlation exists, the authentication sequence continues; if no correlation exists, the authentication sequence does not continue.For example, if there is no correlation, it is very likely that radio waves should not be transmitted directly from the on-board device of the stationary vehicle, and therefore, it is desirable that such authentication as described above not be performed. With the present invention, the execution of the authentication sequence can be restricted even when the terminal device is moving.

[0037] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First embodiment configuration

[0038] Fig. 1 is a functional block diagram of an authentication system 10 according to a first embodiment. The authentication system 10 includes a terminal 100 and a vehicle 400 in which an on-vehicle device 200 is mounted, which is an external device from the perspective of the terminal 100. The terminal 100 is a small, portable device and is typically an electronic key for the vehicle 400. The terminal 100 includes a communication unit 104, a first measuring unit 102, a second measuring unit 103, and a controller 101. The communication unit 104 includes a receiving antenna 105 and a transmitting antenna 106. The on-vehicle device 200 includes a communication unit 204 and a controller 201. The communication unit 204 includes a receiving antenna 205 and a transmitting antenna 206.The on-vehicle device 200 mounted in the vehicle 400 executes a series of authentication sequences by wireless communication with the terminal device 100 carried by a user near the exterior of the stationary vehicle 400, and allows various vehicle operations, such as a door unlock operation, by the user when the authentication is successful.

[0039] The controller 101 of the terminal device 100 and the controller 201 of the on-vehicle device 200 perform transmission and reception of radio signals to and from the communication unit 104 and the communication unit 204 according to a predetermined scheme to execute authentication sequences, respectively. Typically, a signal transmitted by the transmitting antenna 206 of the communication unit 204 of the on-vehicle device 200 and received by the receiving antenna 105 of the communication unit 104 of the terminal 100 is an LF signal, which is a signal at a frequency within an LF band, and a signal transmitted by the transmitting antenna 106 of the communication unit 104 of the terminal 100 and received by the receiving antenna 205 of the communication unit 204 of the on-vehicle device 200 is a radio frequency (RF) signal, which is a signal at a higher frequency than the LF signal. Fig. 2 schematically shows a state in which some magnetic lines of force of the LF signal transmitted from the transmission antenna 206 included in the vehicle 400 pass through the terminal 100.

[0040] The first measuring unit 102 of the terminal 100 can detect a radio wave strength of the LF signal received by the receiving antenna 105 and measure a temporal change in the radio wave strength. The receiving antenna 105 is, for example, a three-axis antenna, and the first measuring unit 102 is preferably capable of detecting radio wave strengths from three axes that are not parallel to each other. By using a multi-axis antenna as described above, it is possible to obtain the temporal change in the radio wave strength as a change in a three-dimensional vector including all components in respective directions, and to obtain a measurement result that more accurately reflects a change in a relative position or a relative orientation between the antenna transmitting the LF signal and the receiving antenna 105.

[0041] The second measuring unit 103 of the terminal device 100 is, for example, an acceleration sensor and can detect acceleration or gravity acting on the terminal device 100 itself, and accurately measure an orientation or position and a temporal change in the orientation or position. Preferably, the acceleration sensor is, for example, a three-axis acceleration sensor, and the second measuring unit 103 can detect acceleration along three axes that are not parallel to each other. By using a multi-axis acceleration sensor as described above, it is possible to obtain a change in the orientation or position of the terminal device 100 as a three-dimensional vector including all components in respective directions, and to obtain a measurement result that more accurately reflects the change in the position or orientation. function

[0042] A process performed by the authentication system 10 is described. Fig. 3 illustrates a process sequence executed when the on-vehicle device 200 and the terminal device 100 of the authentication system 10 can perform communication.

[0043] Step S101: The controller 201 of the on-vehicle device 200 causes the communication unit 204 to transmit a first signal from the transmitting antenna 206. The communication unit 104 of the terminal device 100 receives the first signal from the receiving antenna 105.

[0044] Step S102: When the first signal is received, the controller 101 of the terminal 100 causes the communication unit 104 to transmit a second signal from the transmitting antenna 106, which is a response signal to the first signal. The communication unit 204 of the in-vehicle device 200 receives the second signal from the receiving antenna 205. For example, the first signal is an interrogation signal transmitted at regular intervals to confirm whether the terminal 100 is near the vehicle 400. The controller 201 of the in-vehicle device 200 repeats the transmission of the first signal before confirming receipt of the second signal.

[0045] Step S103: The controller 201 of the in-vehicle device 200 causes the communication unit 204 to transmit a third signal from the transmitting antenna 206. The communication unit 104 of the terminal device 100 receives the third signal from the receiving antenna 105.

[0046] Step S104: When the third signal is received, the controller 101 of the terminal device 100 causes the communication unit 104 to transmit a fourth signal from the transmitting antenna 106, which is a response signal to the third signal. The communication unit 204 of the in-vehicle device 200 receives the fourth signal from the receiving antenna 205. For example, the third signal is a signal including an identifier, such as a type of the vehicle 400, and the fourth signal is a signal that the controller 101 of the terminal device 100 transmits when a determination is made that the terminal device 100 corresponds to the identifier included in the third signal.

[0047] Step S105: The controller 201 of the in-vehicle device 200 causes the communication unit 204 to transmit a fifth signal from the transmitting antenna 206. The communication unit 104 of the terminal device 100 receives the fifth signal from the receiving antenna 105. The processes from step S105 to step S110 are executed in a loop until a determination is made in step S110 that the process exits the loop.

[0048] Step S106: When the fifth signal is received, the controller 101 of the terminal device 100 causes the first measuring unit 102 to measure a radio wave strength of the fifth signal. The first measuring unit 102 measures the radio wave strength and calculates a difference between the radio wave strength measured at this time and a radio wave strength measured at a previous time when no radio wave strength was measured at a previous time in the loop (when this time is a second or subsequent reception of the fifth signal). This difference between the radio wave strengths indicates a change pattern of the radio wave strength and is calculated, for example, as a three-dimensional vector.

[0049] Step S107: When the fifth signal is received, the controller 101 of the terminal device 100 causes the second measuring unit 103 to measure an orientation or a position (hereinafter referred to as an orientation or the like) of the terminal device itself. If an orientation or the like was measured at a previous time in the loop (when this time is a second or subsequent reception of the fifth signal), the second measuring unit 103 calculates a difference between the orientation or the like measured at this time and the orientation or the like measured at the previous time. This difference between the orientations or the like indicates a change pattern of the orientation or the like of the terminal device 100 and is calculated as a three-dimensional vector as an example.An execution order of steps S106 and S107 is not relevant, but it is desirable that steps S106 and S107 are executed in parallel at the same time so that the measurement times are the same.

[0050] Step S108: When the change pattern of radio wave strength and the change pattern of orientation or the like are calculated in steps S106 and S107, the controller 101 of the terminal device 100 determines whether a predetermined correlation exists between the two change patterns described above. Here, the correlation means that a movement pattern relative to a transmission source of the fifth signal, indicated by the change pattern of radio wave strength, and an absolute movement pattern based on acceleration, indicated by the change pattern of orientation or the like, are the same or similar to each other. For example, when a magnitude of the difference vector of the two change patterns is equal to or less than a predetermined value, a determination that the correlation exists can be made, and a determination method is not limited thereto.A correspondence model of the change in orientation or the like and the change in radio wave strength may be generated from a distribution model of the radio wave strength of the LF signal or the like, and a correlation model may be determined based on a degree of similarity to the correspondence model.

[0051] Step S109: The controller 101 of the terminal 100 causes the communication unit 104 to transmit the sixth signal from the transmitting antenna 106, which is a signal including a determination result from step S108. The communication unit 204 of the on-vehicle device 200 receives the sixth signal from the receiving antenna 205.

[0052] Step S110: The controller 201 of the in-vehicle device 200 refers to the determination result included in the sixth signal and returns to step S105 if the determination result is a determination result indicating that there is no correlation, and the in-vehicle device 200 and the terminal device 100 repeat the loop. If the determination result is a determination result indicating that there is a correlation, the process exits the loop and proceeds to step S111.

[0053] Step S111: The controller 201 of the in-vehicle device 200 causes the communication unit 204 to transmit a seventh signal from the transmitting antenna 206. The communication unit 104 of the terminal device 100 receives the seventh signal from the receiving antenna 105.

[0054] Step S112: When the seventh signal is received, the controller 101 of the terminal 100 causes the communication unit 104 to transmit an eighth signal from the transmitting antenna 106, which is a response signal to the seventh signal. The communication unit 204 of the in-vehicle device 200 receives the eighth signal from the receiving antenna 205. The seventh signal and the eighth signal are a request signal and a response signal for performing authentication, for example, based on a request-response scheme.

[0055] Step S113: The controller 201 of the in-vehicle device 200 determines whether authentication was successful based on the eighth signal. The in-vehicle device 200 permits an operation such as unlocking the vehicle if a determination is made that authentication was successful, and prohibits vehicle operation if a determination is made that authentication was unsuccessful.

[0056] In the above example, the authentication sequence is performed through a series of wireless communications for transmitting or receiving signals one to eight. A determination is made regarding the existence of a correlation between the change pattern of radio wave strength based on the fifth signal and the change pattern of orientation or the like of the on-vehicle device 200, before a determination is made as to whether final authentication is successful based on the transmission and reception of the seventh and eighth signals. If there is no correlation, the final authentication is not performed. As described above, the terminal 100 can instruct the on-vehicle device 200 to continue or interrupt the authentication sequence by transmitting the sixth signal including the determination result about the correlation.The content and format of the sixth signal are not limited, as long as the content and format indicate that the on-vehicle device 200 is instructed to continue or interrupt the authentication sequence.

[0057] The change pattern of radio wave strength and the change pattern of orientation or the like are calculated according to the difference between the measured value at the previous time and the measured value at this time in steps S106 to S108. The present invention is not limited to this and can be calculated based on values measured at three or more times. A method for measuring the change pattern of radio wave strength and the change pattern of orientation or the like, or a method for determining the correlation, is not limited, and any suitable method can be selected.

[0058] Conditions for exiting the loop are not limited as long as the final authentication can be prevented from being executed when there is no correlation. For example, in step S110, the controller 201 of the on-vehicle device 200 does not immediately exit the loop when the determination result included in the sixth signal indicates that there is a correlation, and may exit the loop when it receives the sixth signal including a determination result indicating that there is no correlation. If the sixth signal including the determination result indicating that there is no correlation is received multiple times, the repetition of the execution of step S105 may be stopped so that the fifth signal is not transmitted. Erroneous determination can be reduced by being based on results of a plurality of determinations.If the controller of the terminal device 100 determines that there is no correlation in step S109, the controller of the terminal device 100 may not transmit the sixth signal. In this case, in step S110, if the sixth signal is not received within a predetermined time, the controller 201 of the on-vehicle device 200 may operate similarly to a case where the sixth signal containing the determination result indicating that there is no correlation is received as described above. Effects

[0059] There is a correlation between the change pattern of radio wave strength based on the fifth signal and the change pattern of the orientation or the like of the on-vehicle device 200, even if the terminal device 100 is moving, as long as the fifth signal is directly transmitted from the transmission antenna 206 of the on-vehicle device 200 mounted on the stationary vehicle 400 to the reception antenna 105 of the terminal device 100. If there is no correlation, it is highly likely that the fifth signal should not be directly transmitted from the transmission antenna 206 of the on-vehicle device 200. According to the first embodiment, it is possible to interrupt the authentication sequence in such a case and impose restrictions on not executing the final authentication sequence. Second embodiment configuration

[0060] Fig. 4 illustrates a functional block diagram of an authentication system 11 according to a second embodiment. The authentication system 11 differs from the authentication system 10 according to the first embodiment in that the authentication system 11 includes a terminal 110 and a vehicle 410 in which the on-vehicle device 210 is mounted, and the on-vehicle device 210 includes a first transmission antenna 306 and a second transmission antenna 307. Descriptions of the same items as those of the first embodiment are omitted. Fig. 5 schematically illustrates a state in which some magnetic lines of force of the LF signal transmitted from the first transmission antenna 306 and the second transmission antenna 307 included in the vehicle 410 pass through the terminal 110. The first transmission antenna 306 is placed at the same position as the transmission antenna 206 in the first embodiment, and the second transmission antenna 307 is placed at a different position. function

[0061] In the second embodiment, the in-vehicle device 210 and the terminal 110 perform wireless communication as in the first embodiment to execute an authentication sequence. In this case, the controller 201 of the in-vehicle device 210 controls the communication unit 204 to transmit signals one, three, five, and seven using the first transmission antenna 306. Further, the controller 201 controls the communication unit 204 to transmit at least the fifth signal from the second transmission antenna 307. However, the signal from the second transmission antenna 307 is transmitted at a different timing than the first transmission antenna 306 transmits a signal, thus avoiding interference.

[0062] The processes from steps S106 to step S108 shown in Fig.3 are performed on the fifth signals transmitted from the first transmission antenna 306 and the second transmission antenna 307. That is, the change pattern of the radio wave strength is measured for both the fifth signal transmitted from the first transmission antenna 306 and the fifth signal transmitted from the second transmission antenna 307, and a correlation is determined between each change pattern of the radio wave strength and the change pattern of the orientation or the like of the terminal 100. In step S108, a final determination that the correlation exists can be made only when there is a correlation between each change pattern of the radio wave strength and the change pattern of the orientation. Identification of the fifth signal can be performed, for example, by including an identifier of a transmission source antenna to be included in the fifth signal.

[0063] In the second embodiment, the following process may be further performed. That is, the first measuring unit 102 measures the change pattern of the radio wave strength for both the fifth signal transmitted from the first transmission antenna 306 and the fifth signal transmitted from the second transmission antenna 307, and calculates a difference between the respective radio wave strengths. It is desirable that the difference be a vector difference. The controller 101 may determine whether the vector difference caused by a relative positional relationship between the first transmission antenna 306 and the second transmission antenna 307 occurred within a constant range.That is, a determination is made as to whether the vector difference is within a predetermined range, and if the vector difference is not within the predetermined range, the sixth signal transmitted in step S109 is a signal for instructing the on-vehicle device 200 to interrupt the authentication sequence regardless of a determination result about the correlation in step S108. A range of the vector difference serving as the determination difference may be appropriately determined based on a range of a vector difference that can be generated in a position range where the fifth signal can be directly received. The range of the vector difference may be only a magnitude or may include a direction. In a case where the range includes the direction, the direction may be corrected according to an orientation of the terminal 110 measured by the second measuring unit 103. Effects

[0064] It is possible to improve an accuracy of determination compared with the first embodiment by performing the determination of the correlation between the change pattern of radio wave strength and the change pattern of orientation or the like on radio waves transmitted from the transmission antennas at two different positions.

[0065] Furthermore, when the fifth signals, each transmitted from the first transmission antenna 306 and the second transmission antenna 307 of the in-vehicle device 210 mounted in the vehicle 410, are directly transmitted to the receiving antenna 105 of the terminal 100, the respective radio wave strength vectors have a constant vector difference caused by the relative positional relationship between the first transmission antenna 306 and the second transmission antenna 307. Therefore, it is highly likely that the fifth signal should not be directly transmitted from the first and second transmission antennas if there is no vector difference as described above. According to the second embodiment, even in the above-described case, it is possible to restrict the authentication sequence so that it is not executed to the end.The determination based on the vector difference as described above can be performed even when the terminal device 110 is stationary, the amount of change in radio wave strength and the amount of change in orientation or the like are small, and the accuracy of the determination regarding the correlation of each change pattern is insufficient. The number of transmission antennas is not limited to two, and signals transmitted from three or more transmission antennas can be used for one determination. The determination of the correlation using the change pattern of orientation or the like can be omitted, and the determination can be performed using only a difference between the radio wave strength vectors of the signals from a plurality of antennas.

[0066] The authentication sequence described in each of the above embodiments is an example, and the content of the radio signal, as well as the flow and format of transmission and reception, are not limited thereto. A radio signal serving as the measurement target of the radio wave strength can be any radio signal, as long as it is one that is present before final authentication is performed.

[0067] The present invention can be regarded not only as a configuration of functional blocks of an authentication system or a terminal, but also as a method to be executed by the authentication system or the terminal comprising a processor.

[0068] The present invention is useful for an electronic key system for a vehicle or the like.

Claims

[1] A terminal (100, 110) that performs an authentication sequence by means of wireless communication with an external device, the terminal comprising: a communication unit (104) configured to transmit or receive a radio signal to be used for the authentication sequence; a first measuring unit (102) configured to measure a change in radio wave strength for at least a portion of the radio signal received by the communication unit (104); a second measuring unit (103) configured to measure a change in an orientation or a position of the terminal device (100, 110); and a controller (101) which is configured to determine whether there is a correlation between a measurement result of the first measuring unit (102) and a measurement result of the second measuring unit (103), i) continue the authentication sequence if the controller determines that a correlation exists, and ii) interrupt the authentication sequence if the controller determines that there is no correlation. [2] Terminal (100, 110) according to claim 1, wherein: the communication unit (104) comprises a multi-axis antenna comprising a plurality of axes that are not parallel to each other; and the first measuring unit (102) is arranged to measure a change in a radio wave strength for each axis of the multi-axis antenna. [3] Terminal (100, 110) according to claim 1 or 2, wherein the communication unit (104) comprises an antenna configured to receive a radio signal in a low frequency band (LF band) as a radio signal. [4] The terminal (100, 110) according to any one of claims 1 to 3, wherein the second measuring unit (103) comprises an acceleration sensor and is configured to measure the change in the orientation or the position based on an output of the acceleration sensor. [5] The terminal (100, 110) according to claim 4, wherein the acceleration sensor is a multi-axis acceleration sensor. [6] Terminal (100, 110) according to one of claims 1 to 5, wherein the terminal (100, 110) is an electronic key for a vehicle. [7] Terminal (100, 110) according to one of claims 1 to 6, wherein the controller (101) is arranged to cause the communication unit (104) not to transmit the radio signal for the authentication sequence if the controller determines that there is no correlation. [8] Terminal (100, 110) according to one of claims 1 to 6, wherein the controller (101) is arranged to cause the communication unit (104) to transmit a radio signal instructing to interrupt the authentication sequence when the controller determines that there is no correlation. [9] Terminal (100, 110) according to one of claims 1 to 8, wherein: the communication unit (104) is configured to receive the radio signal transmitted at different times from a plurality of positions, the radio signal being used for the authentication sequence; the first measuring unit (102) is arranged to measure a change in the radio wave strength of the radio signal transmitted from each of the positions; and the controller (101) is set up to determine whether there is a correlation between a measurement result of the first measuring unit (102) and a measurement result of the second measuring unit (103) for each of the positions, i) continue the authentication sequence if the controller determines that the correlation exists at all positions, and (ii) interrupt the authentication sequence if the controller determines that there is no correlation between at least one of the positions. [10] Terminal (100, 110) according to claim 9, wherein: the first measuring unit (102) is arranged to calculate a difference vector of the radio wave strength between radio signals transmitted from the respective positions; and the controller (101) is arranged to interrupt the authentication sequence if the difference vector is not within a predetermined range, regardless of a result of the determination as to whether the correlation exists. [11] Authentication system (10, 11) comprising: the terminal (100, 110) according to one of claims 1 to 8; and a vehicle (400, 410) comprising an on-board device (200, 210) that performs the authentication sequence by wireless communication with the terminal (100, 110), wherein the on-board device is the external device. [12] Authentication system (10, 11) according to claim 11, wherein the on-vehicle device (200, 210) comprises: an on-board communication unit (204) comprising a receiving antenna (205) and a transmitting antenna (206) and configured to transmit or receive the radio signal to be used for the authentication sequence, and an on-vehicle controller (201) that performs control such that the on-vehicle communication unit (204) performs transmission or reception of the radio signal. [13] Authentication system (10, 11) comprising: the terminal (100, 110) according to claim 9 or 10; and a vehicle (400, 410) comprising an on-board device (200, 210) that performs the authentication sequence by means of wireless communication with the terminal (100, 110), wherein the on-board device is the external device, wherein the on-vehicle device (200, 210) is configured to transmit the radio signal to be used for the authentication sequence from a plurality of positions of the vehicle (400, 410). [14] Authentication system (10, 11) according to claim 13, wherein the on-vehicle device (200, 210) comprises: an on-board communication unit (204) comprising a receiving antenna (205) and a plurality of transmitting antennas (206) and configured to transmit or receive the radio signal to be used for the authentication sequence, and an on-vehicle controller (201) that performs control such that the on-vehicle communication unit (204) performs transmission or reception of the radio signal. [15] An authentication control method executed by a terminal (100, 110) executing an authentication sequence by wireless communication with an external device, the authentication control method comprising: Transmitting or receiving a radio signal to be used for the authentication sequence; measuring a change in radio wave strength for at least a portion of the received radio signal; Measuring a change in orientation or position of the terminal (100, 110); and Determining whether a correlation exists between a measurement result of the change in radio wave strength and a measurement result of the change in orientation or position, i) continuing the authentication sequence if the controller determines that the correlation exists, and ii) interrupting the authentication sequence if the controller determines that no correlation exists.

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