Method for operating a keyless access system for a motor vehicle

Abstract

The invention relates to a method for operating a keyless access system (11) for a motor vehicle (1), wherein the motor vehicle (1) comprises a radar system (2) comprising several spatially distributed individual transmit and receive modules (3) and a central control unit (4), wherein the radar system (2) uses at least partially optical transmission techniques for the transmission of signals within the radar system.The procedure comprises: generating, transmitting within the radar system, and emitting at least one output signal (5); receiving at least one response signal (9) emitted by a mobile device (6) assigned to the motor vehicle (1) and / or a user of the motor vehicle (1) and which has received the emitted output signal (5), by means of at least one part of the transmit and receive modules (3), and transmitting it within the radar system; checking whether the at least one received response signal (9) meets a predetermined admissibility criterion (10) by means of the central control unit (4); and, if so, permitting the operation of the keyless entry system (11) by means of the mobile device (6).

Description

[0001] The invention relates to a method for operating a keyless entry system for a motor vehicle. The motor vehicle comprises a radar system that includes several spatially distributed individual transmitter and receiver modules as well as a central control unit. The radar system uses at least partially optical transmission techniques for the internal transmission of signals between the individual transmitter and receiver modules and the central control unit. The invention also relates to a motor vehicle and a system for carrying out such a method.

[0002] A motor vehicle can be equipped with a keyless entry system. With this system, at least one door and / or the trunk of the vehicle can be opened as soon as a mobile device, such as a key assigned to the vehicle or a smartphone, is within a predefined area of ​​the vehicle. This requires, for example, no operation of any control on the mobile device and / or inserting and turning the device into a lock. A user can therefore approach the vehicle, for instance, carrying the mobile device, without having to actively operate it, and yet a door of the vehicle can still be automatically unlocked and / or opened.If the mobile device is located inside the vehicle, the keyless access system can, for example, automatically allow the vehicle's engine to be started.

[0003] Typically, a keyless entry system is designed so that a sensor in a door and / or trunk handle of the vehicle continuously monitors whether a hand is approaching the handle. It can also transmit a short-range radio signal, which can be received and processed by a mobile device. The mobile device then sends a response signal back to the vehicle. If the mobile device is within the vehicle's designated vicinity, which can be determined, for example, by measuring the response signal's travel time, the door lock can be released, and the user can open the door as soon as the sensor detects their hand on the handle.

[0004] WO 2023 / 120307 A1 shows a control unit for transmitting a low-frequency signal using several low-frequency transmitters.

[0005] US 2013 / 0143594 A1 discloses a device for determining the location of a portable wireless device in relation to a vehicle.

[0006] US 2020 / 0339066 A1 discloses a method for controlling a key comprising a low-frequency receiver that receives a low-frequency signal from a vehicle. A radio-frequency signal is transmitted from the key to the vehicle in response to the low-frequency signal.

[0007] DE 10 2023 122 094 A1 describes a control unit for use in a motor vehicle with a measuring device and a storage device, wherein the control unit is configured as a first control unit to be connected to a second control unit for the motor vehicle via a wired connection, the first control unit is configured to send a measurement pulse through the measuring device via the wired connection upon receipt of a verification message and to determine measurement data during a predetermined period of time from the transmission of the measurement pulse until the receipt of one or more reflection signals of the measurement pulse; and the first control unit is configured to compare the determined measurement data with predetermined reference measurement data in order to determine the authenticity of the verification message.

[0008] A typical keyless entry system therefore requires at least one transmitter and receiver in the vehicle, capable of transmitting and receiving signals in selected frequency ranges, such as the low-frequency range. To minimize the number of components required in the vehicle, or at least to avoid increasing it further, it can be advantageous to implement the keyless entry system using a single vehicle component that can be used for multiple tasks and / or vehicle functions. An example of such a component could be the vehicle's radar system, which could be suitable for both environmental sensing and as a transmitter and receiver for the keyless entry system.

[0009] The object of the invention is to provide a solution by means of which a keyless access system can be integrated into an existing motor vehicle.

[0010] The problem is solved by the subject matter of the independent patent claims.

[0011] A first aspect of the invention relates to a method for operating a keyless access system for a motor vehicle. The keyless access system is, for example, a system with which at least one door and / or trunk and / or window of the motor vehicle can be unlocked, locked, opened, and / or closed without the activation or detection of an actuating element of a mobile device, such as a key and / or a smartphone. The keyless access system can alternatively or additionally be configured to allow the motor of the motor vehicle to be started by actuating an actuating element in the motor vehicle. The actuating element used for this purpose is, for example, a start-stop button.The keyless entry system is based on a signal exchange between a transmitter and / or receiver in the vehicle and a transmitter and / or receiver in the mobile device, indicating that the mobile device is within a predefined area of ​​the vehicle. Furthermore, at least one sensor in the vehicle, particularly a capacitive sensor, can detect whether a user's hand is approaching a door handle, trunk handle, and / or window. Only when this approach occurs, or even when the device is touched, can unlocking, locking, opening, and / or closing be triggered. The keyless entry system is therefore an automatically controlled remote access system that requires no manual activation by a user.

[0012] The invention is based on the understanding that even encrypted communication between a motor vehicle and a vehicle key can be hacked under certain circumstances, for example, through relay attacks. The aim is not to decrypt the encrypted communication, but rather to bridge the distance between the motor vehicle and the key using amplifier systems, so-called relay stations. In this case, for example, the door handle is operated near the motor vehicle, whereupon the motor vehicle sends its usual output signal to the key. This signal is received by a special module and transmitted on a different communication channel with significantly higher power in a relay mode to another, more distant module located near a user of the motor vehicle and thus near the key.There, the output signal is transmitted at its original frequency and received by the key. The key responds with a signal to open, for example, the door, which is then transmitted back to the vehicle via the module. The vehicle then opens the door and can even start the engine. Using this method, without knowledge of the encryption, the distance between the vehicle and the key can be extended to such an extent that the vehicle can, for example, be stolen.

[0013] Measures against relay attacks are known. For example, the signal propagation time between the transmission of the output signal and the receipt of the key's response signal can be measured and evaluated. Only if the response signal is received within a predefined time window can it be assumed that no relay station is involved and that the key is actually located in the vicinity of the vehicle. Ultra-wideband systems can be used for this purpose, for example.

[0014] However, it can be advantageous to utilize devices already installed in the vehicle. For example, a radar system already integrated into the vehicle is suitable. One such radar system is based on optical transmission technologies, which can alternatively be referred to as photonic radar. If the radar system is used for the keyless entry system, it can be integrated into an existing vehicle. Thus, a component of the vehicle—in this case, the radar system—which is already intended for environmental sensing, can also be used for the keyless entry system without requiring any hardware modifications or adjustments to the radar system.

[0015] The motor vehicle that performs the method for operating the keyless entry system therefore comprises a radar system that includes several spatially distributed individual transmit and receive modules as well as a central control unit. The individual transmit and receive modules of the radar system can, for example, be arranged around the entire motor vehicle. The radar system has exactly one central control unit configured to control the multiple individual transmit and receive modules. Thus, the radar system has a plurality of transmit and receive modules and a single central control unit for controlling the plurality of transmit and receive modules. The respective transmit and receive module can alternatively be understood as a transmit and receive antenna module. The transmit and receive module can each comprise at least one transmit antenna and at least one receive antenna, or at least one transmit and receive antenna.The transmit and receive module can alternatively be understood as a radar device, the control of which is carried out via the central control unit of the radar system.

[0016] The radar system uses at least partially optical transmission techniques for the internal transmission of signals between the individual transmit and receive modules and the central control unit. The internal transmission of signals thus utilizes optical transmission techniques, at least in part. In one example, the internal transmission of signals is not only partially but entirely achieved using optical transmission techniques. A signal within the meaning of the invention can alternatively be understood as data and / or information. The signal is associated with at least one frequency. The signal can therefore be understood as an electromagnetic wave with a predetermined frequency, which can be transmitted and / or received, for example, by means of the respective transmit and receive module.Radar system-internal transmission within the meaning of the invention comprises transmissions within the radar system, that is, between individual components of the radar system. The radar system-internal transmission of signals between the individual transmit and receive modules and the central control unit can include transmissions within the individual transmit and receive modules and / or within the central control unit, which take place so that the signal can be transmitted between the individual transmit and receive modules and the central control unit.

[0017] Due to the at least partially optical and therefore fast transmission of signals between the central control unit and the multiple transmitting and receiving modules, the described radar system, compared to a radar system not based on optical transmission, can achieve fast and simultaneous control of the transmitting and receiving modules at different locations in or on the vehicle. This enables a high-resolution radar system with which the vehicle's surroundings can be precisely monitored. The radar system is therefore also suitable for operating the keyless entry system and thus for carrying out the following procedure: The method comprises generating at least one output signal by means of the central control unit. The output signal is a signal. The output signal can alternatively be referred to as the first signal, vehicle signal, or request signal. The central control unit can, for example, specify the output signal with a predetermined frequency. The frequency of the output signal can be high-frequency or low-frequency. The at least one generated output signal is then transmitted internally within the radar system to at least some of the transmit and receive modules. In a preferred example, the output signal is transmitted internally within the radar system to all transmit and receive modules of the transmit and receive module. The method comprises transmitting the at least one output signal by means of at least some of the transmit and receive modules.The transmitted output signal can correspond to the output signal generated by the central control unit or can differ at least partially from the generated output signal. Thus, in a preferred example, the generated output signal and the transmitted output signal are identical, but alternatively, they can differ from each other, particularly with respect to frequency. In a preferred example, the generated output signal is transmitted to all transmit and receive modules of the radar system and transmitted by them.

[0018] The generated, transmitted and emitted output signal can alternatively be understood as a control command, which is generated by the central control unit for at least some of the transmitting and receiving modules, transmitted to them and converted into an electromagnetic wave to be emitted by a control unit of the respective transmitting and receiving module, which is then emitted.

[0019] The procedure involves receiving at least one response signal to the output signal using at least one part of the transmitting and receiving modules. This part of the transmitting and receiving modules may be the same as the part that transmitted the output signal or at least partially different from it. The response signal may alternatively be referred to as a second signal or device signal. The response signal was transmitted by the mobile device. The mobile device is associated with the motor vehicle and / or the vehicle's user. The mobile device may have previously received the output signal. The response signal is also a signal. The at least one received response signal is then transmitted internally within the radar system to the central control unit. This unit then checks whether the at least one received response signal, transmitted internally within the radar system, meets a predefined admissibility criterion.The specified admissibility criterion stipulates, for example, the maximum distance at which the mobile device can be positioned from the motor vehicle in order to operate the keyless access system.

[0020] The specified admissibility criterion includes, for example, at least one rule and / or regulation and / or algorithm, the execution or application of which, in conjunction with the output signal, allows for the determination of whether the response signal is suitable for permitting the operation of the keyless access system. Various sub-criteria of the admissibility criterion may be provided for this purpose, one, several, or all of which must be fulfilled to conclude that the operation of the keyless access system should be permitted.

[0021] If the verification process determines that at least one received response signal meets the specified reliability criterion, operation of the keyless access system via the mobile device is authorized. This allows, for example, the automatic unlocking or locking of at least one door and / or trunk and / or window of the vehicle. In other words, the keyless access system can automatically move at least one door and / or trunk and / or window of the vehicle into an open or at least partially open position and / or from a partially open position to a closed position. In this case, the respective door and / or trunk and / or window has a correspondingly controllable adjustment mechanism.It may also be stipulated that the reliability criterion additionally requires that at least one of the user's hands has approached or touched a door handle, a trunk handle, and / or a window. Only if this is the case can the operation of the keyless entry system be permitted in a given example.

[0022] The mobile device is, for example, a mobile phone, such as a smartphone and / or a tablet. Alternatively or additionally, the mobile device could be a smart key for a motor vehicle. Alternatively or additionally, the mobile device could have a transmitting and / or receiving unit capable of transmitting and receiving ultra-wideband signals. In this example, the mobile device might not have a dedicated transmitting and receiving module. A device or assembly capable of emitting an electromagnetic wave at a predetermined frequency is sufficient.

[0023] Advantages of the described method include the fact that no additional components need to be integrated into the vehicle along with the radar system. The evaluation of the response signal is performed using the same hardware that is also used for the radar system and the transmission of the output signal. The precision in determining the position and / or orientation of the mobile device relative to the vehicle can be increased by using multiple transmit and receive modules. Furthermore, costs can be reduced, and security against relay attacks is enhanced.

[0024] In summary, the vehicle's radar system can be used in radar mode, where a large antenna is virtually deployed using the multiple transmitting and receiving modules, enabling high-resolution scanning of the vehicle's surroundings. However, the invention focuses on using the radar system to operate the keyless entry system. Therefore, instead of radar signals, the signals required for communication with the mobile device—that is, the output signal—are transmitted via the individual transmitting and receiving modules.

[0025] One embodiment includes a signal-encoded output signal. The received response signal fulfills the specified admissibility criterion only if it is correlated with the signal-encoded output signal. The response signal and the signal-encoded output signal are correlated, for example, if they are compatible. In one example, the specified admissibility criterion may be fulfilled only if the response signal has a signal encoding that is correlated with or compatible with the signal-encoded output signal. In this example, both the output signal and the response signal are signal-encoded, and the signal encodings are correlated. Each signal-encoded signal has a signal encoding. For the purposes of the invention, the signal-encoded signal can be understood as an encrypted signal, that is, a signal that is encrypted or has an encryption.In other words, the exchange of the output signal and the response signal can be encrypted, that is, signal-encoded or coded, so that, for example, only the mobile device assigned to the vehicle and / or the vehicle's user can generate a response signal that matches the output signal and is therefore assessed as fulfilling the specified admissibility criterion during verification. This results in an admissibility criterion that is only met in secure situations, since the signal encoding, and thus an additional safeguard compared to transmitted and / or received signals without signal encoding, must be taken into account.

[0026] Another embodiment provides that the central control unit determines the propagation time of the received response signal by examining it. The specified admissibility criterion is only met if, by evaluating the determined propagation time, it is established that the mobile device is located within a predefined area around the vehicle. This predefined area can, for example, be limited to a radius of 2 meters, 5 meters, 8 meters, 10 meters, 15 meters, or, in particular, 20 meters around the vehicle. Known methods for determining signal propagation time can be used. For example, time synchronization between the vehicle and the mobile device can be performed, and / or a timestamp of the transmission of the at least one output signal can be compared with a timestamp of the reception of the response signal to calculate the propagation time.The process ultimately determines the estimated distance between the mobile device and the vehicle to verify whether it is within the vehicle's designated vicinity. This ensures that a mobile device located, for example, several hundred meters away, is not authorized to operate the keyless entry system. It thus verifies actual spatial proximity between the mobile device and the vehicle. This establishes an admissibility criterion that, at the very least, helps protect the keyless entry system from potential hacking or other attacks.

[0027] Another embodiment provides that at least parts of the transmitting and receiving modules continuously receive response signals from the mobile device. The mobile device can, for example, be operated in a mode in which the response signal is continuously transmitted, for instance, at predetermined time intervals. This can occur, for example, after receiving an initial or single output signal, or independently of receiving the output signal. The mobile device can, for example, autonomously transmit the response signal repeatedly.

[0028] The central control unit uses a relative arrangement determination criterion applied to the continuously received response signals to determine the relative arrangement of the mobile device to the vehicle. This relative arrangement includes, in particular, the relative position and / or orientation of the mobile device relative to the vehicle. The relative orientation can be understood, for example, as the angle between the mobile device and the vehicle. The relative position can be specified, for example, as a coordinate. This allows the mobile device to be located or localized, enabling, for instance, a highly reliable tracking of the direction from which the mobile device is approaching or moving away from the vehicle. This, in turn, allows for the automatic unlocking of at least one door and / or the trunk of the vehicle, if necessary, upon approach.If the mobile device moves away from the vehicle, at least one door and / or the trunk can be automatically locked instead. The specified admissibility criterion is only met if the mobile device is positioned within a predefined area of ​​the vehicle according to the determined relative arrangement. This predefined area may correspond to the predefined area described above or may differ from it, at least in part.

[0029] The relative arrangement determination criterion comprises at least one algorithm and / or a procedure and / or a rule, the application of which to the response signals allows the relative arrangement to be determined. For this purpose, for example, an evaluation of the field strength of the response signals and / or a signal propagation delay difference of the response signals to the individual transmit and receive modules of the radar system can be considered. Furthermore, for example, the direction from which the response signal is received by the respective transmit and receive module can be determined; that is, a so-called direction-of-arrival (DOA) analysis can be performed. The radar system can thus operate analogously to a passive radar. This requires that the position of the individual transmit and receive modules of the radar system within the vehicle is known. This leads to a precise localization of the mobile device in the vicinity of the vehicle.

[0030] Furthermore, one embodiment provides for a check to see if the response signal is received from outside the vehicle. If this is the case, that is, if the response signal is received from outside the vehicle, then, if the operation of the keyless access system via the mobile device is permitted, at least one automatic unlocking and / or locking of at least one locking device of a door and / or trunk of the vehicle is allowed. Thus, it is checked whether the mobile device is located inside the vehicle or not. It can be assumed that it has already been checked whether the at least one received response signal meets the specified admissibility criterion, and that this is the case, so that the operation of the keyless access system via the mobile device has already been permitted.If it is also detected that the mobile device is located outside the vehicle, i.e., in or near the vehicle, the described automatic unlocking and / or locking of the vehicle's door and / or trunk locking mechanism is permitted. This is particularly convenient for a user approaching or moving away from the vehicle.

[0031] Additionally or alternatively, automatic opening and / or closing of at least one door and / or the trunk and / or at least one window of the vehicle may be permitted. Further functions of the keyless entry system that can be triggered from outside the vehicle may also be provided. This prevents, for example, the locking mechanism of the door from being activated when the mobile device is inside the vehicle and thus locked inside.

[0032] Another embodiment involves checking whether the response signal is received from inside the vehicle. In other words, it verifies whether the mobile device is located inside the vehicle. If this is the case, meaning if the response signal is received from inside the vehicle, then allowing the operation of the keyless entry system via the mobile device will at least permit the vehicle's engine to start. For the vehicle's engine to actually start, it may also be necessary to manually operate or activate a control or actuation element inside the vehicle, such as a start-stop button.As soon as the control or actuating element is activated, and if the response signal is also received from inside the vehicle, the engine of the vehicle can be started without, for example, the mobile device having to be operated further or inserted into an ignition lock of the vehicle.

[0033] To determine whether the response signal is being received from inside the vehicle, individual transmitting and receiving modules of the radar system must be located inside the vehicle, for example, on or in the vehicle roof. It is possible to have two separate radar systems: one for monitoring the vehicle's surroundings and the other for monitoring the vehicle's interior. Alternatively, all transmitting and receiving modules can be assigned to a single, common radar system with exactly one central control unit.Furthermore, for example, if the operation of the keyless access system is permitted upon receiving a response signal from inside the vehicle, it can be prevented that the mobile device is used to automatically unlock and / or lock at least the locking mechanism of the door and / or trunk of the vehicle, in order to prevent the mobile device from being locked inside the vehicle if it is forgotten or lost.

[0034] In an additional embodiment, the position of the mobile device within the vehicle interior is determined by applying a position determination criterion to the received response signal using the central control unit. It is then verified whether the determined position is located within the area of ​​the driver's seat. Only if this is the case, i.e., if the determined position is located within the area of ​​the driver's seat, is the vehicle's engine allowed to start. Thus, the precise location of the origin of the response signal, i.e., the mobile device, within the vehicle's interior can be determined. This prevents, for example, children playing in the vehicle from starting the engine while a person with the mobile device has left the vehicle.Therefore, it is not possible to allow the vehicle's engine to start if the mobile device is positioned, for example, on a rear seat or passenger seat. This is a safeguard against potential hazards when starting the vehicle's engine.

[0035] The position determination criterion includes at least one algorithm and / or a regulation and / or a rule, the application of which to the response signals allows the position of the mobile device inside the motor vehicle to be determined.

[0036] A preferred embodiment provides that at least the output signal can be in the megahertz range. It lies between 400 megahertz and 900 megahertz. For example, the signal can be 433 megahertz or 868 megahertz. Alternatively, the megahertz range, and thus the output signal, can be between 1 megahertz and 999 megahertz. Alternatively, the output signal can be in any other frequency range, which can be between 1 gigahertz and 77 gigahertz, or in the hertz range (1 hertz to 999 hertz), or in the kilohertz range (1 kilohertz to 999 kilohertz). The response signal can be in the same, a different, or at least partially overlapping frequency range. For example, the response signal can be in the gigahertz range or the kilohertz range.The megahertz range is suitable for a mobile device with a simple transmitting and / or receiving setup, so that hardware requirements for the mobile device can be kept low and / or compatibility with many mobile devices can be achieved.

[0037] In a preferred example, the method is carried out when the motor vehicle is parked, for example, when a parking brake is engaged and / or a parking gear position is selected and / or the motor vehicle's engine is switched off. Another embodiment includes at least one optical fiber connecting, at least partially, the central control unit and the individual transmit and receive modules of the radar system. The at least one optical fiber enables the transmission of signals within the radar system, that is, data and / or information that is optically encoded. The optically encoded signals, such as the output signals or other control commands for the transmit and receive modules and / or the response signal, or radar information acquired by means of the transmit and receive modules, can be coupled into the at least one optical fiber and transmitted via the at least one optical fiber.In particular, all internal communication between each of the transmitting and receiving modules on the one hand and the central control unit on the other takes place via fiber optic cable, specifically via multiple fiber optic cables. This illustrates how reliable data transmission within the optical radar system can be achieved.

[0038] Another embodiment provides that the central control unit includes an optical transmitter. The optical transmitter sends the output signal in optically encoded form. For example, it can send at least one output signal for each of the multiple transmitter and receiver modules. The output signals can be different or identical. The optical transmitter couples the optically encoded output signal into the at least one optical fiber that connects the central control unit and the transmitter and receiver module that will send the output signal. Each transmitter and receiver module includes an optical receiver that receives the optically encoded output signal and converts it into an electronically encoded output signal. The respective transmitter and receiver module then sends electromagnetic waves corresponding to the electrically encoded output signal that was encoded by the optical receiver.The output signal, initially transmitted optically and then converted into an electrically encoded signal, includes, for example, a frequency, beam size, beam direction, and / or other settings for the electromagnetic waves to be emitted by a transmitting antenna or a combined transmitting and receiving antenna of the transmitter and receiver module. In this way, each of the multiple transmitter and receiver modules receives the output signal particularly quickly. Analogous to the output signal, a control command for the respective transmitter and receiver module can be generated and transmitted, for example, if a radar measurement is to be carried out using the transmitter and receiver modules.

[0039] In one example, each transmit and receive module includes only one transmit antenna, so that, as described, only output signals for transmission via the transmit antenna are provided. The transmit antenna can be a transmit and receive antenna. The transmit and receive module can include multiple transmit antennas and / or transmit and receive antennas. In this case, the output signal for each transmit antenna can be provided individually.

[0040] Another embodiment includes an optical modulation unit in each transmitting and receiving module. The optical modulation unit converts the received response signal into an optically encoded response signal and couples this signal into the at least one optical fiber. The response signal is an electromagnetic wave emitted by the mobile device. The received response signal is converted into an optically encoded response signal, which is transmitted via the optical fiber to the central control unit. The central control unit comprises an optical receiving unit and an evaluation unit. The optical receiving unit receives the optically encoded response signal from the optical fiber, and the evaluation unit processes the optically encoded response signal.This means that the response signal is initially transmitted as optically encoded information and then converted back into a signal suitable for further processing by the central control unit. This explains how the optical transmission of response signals is carried out within the radar system to reduce transmission times.

[0041] Another embodiment provides that the optically encoded output signal or response signal is generated by modulating the respective signal to a predetermined optical carrier frequency. In particular, the respective signal is modulated with a predetermined fraction of the frequency of the transmitted electromagnetic wave. Alternatively or additionally, the optically encoded response signal is generated by modulating the received response signal to a predetermined optical carrier frequency. In particular, it is modulated with a predetermined fraction of the frequency of the received response signal. In a preferred example, the fraction is 1 / 8. This can be done analogously or with a different fraction for the output signal. It thus becomes clear how the conversion between optically encoded and electronically encoded signals is achieved in accordance with the invention.

[0042] For use cases or application situations that may arise during the procedure and are not explicitly described here, it may be provided that, according to the procedure, an error message and / or a request for user feedback is issued and / or a default setting and / or a predetermined initial state is set.

[0043] Another aspect of the invention relates to a motor vehicle with a radar system as described above. The motor vehicle thus has a radar system comprising several spatially distributed individual transmitting and receiving modules and a central control unit. The radar system uses at least partially optical transmission techniques for the internal transmission of signals between the individual transmitting and receiving modules and the central control unit. The motor vehicle is selected to carry out the method described above. The motor vehicle carries out the method described above.

[0044] Another aspect of the invention relates to a system comprising a motor vehicle as described above and a mobile device with at least one transmitting and / or receiving unit. The system is configured to perform the method described above. The method can further include the mobile device generating and transmitting the response signal to the received output signal, so that the at least one response signal transmitted by the mobile device can be received in the motor vehicle by at least some of the transmitting and receiving modules.

[0045] The central control unit and / or the mobile device includes, for example, a processor. This processor may contain at least a microprocessor, microcontroller, FPGA (Field Programmable Gate Array), and / or DSP (Digital Signal Processor). Furthermore, it may contain program code, which can alternatively be referred to as a computer program product. The program code may be stored in a data memory of the processor.

[0046] The invention includes further developments of the motor vehicle and system according to the invention, which have features already described in connection with the embodiments of the method according to the invention. For this reason, the corresponding further developments are not described again.

[0047] The invention comprises combinations of the features of the described embodiments.

[0048] The following describes exemplary embodiments of the invention. This is illustrated by: Fig. 1 a schematic representation of a motor vehicle with a radar system; Fig. 2. A schematic representation of a signal flow graph of a method for operating a keyless access system for a motor vehicle; and Fig. 3 A schematic representation of a radar system for a motor vehicle.

[0049] The embodiments described below are preferred embodiments of the invention. In these embodiments, the described components each represent individual features of the invention that can be considered independently of one another. Each of these features further develops the invention independently and can therefore be considered part of the invention individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by other features of the invention already described.

[0050] In the figures, functionally identical elements are each provided with the same reference symbols.

[0051] Fig. Figure 1 shows a motor vehicle 1 from various perspectives, showing the front, rear, and side of the motor vehicle 1. The motor vehicle 1 includes a radar system 2. The radar system 2 comprises several transmitting and receiving modules 3. The transmitting and receiving modules 3 are preferably spatially distributed around the motor vehicle 1. In a preferred example, they are located at different positions in the vertical (z-direction), longitudinal (x-direction), and / or transverse (y-direction) direction of the motor vehicle 1. The individual transmitting and receiving modules 3 can, for example, be located on an A-, B-, C-, or D-pillar of the motor vehicle 1. In particular, at least some of the transmitting and receiving modules 3 can be arranged on a bumper of the motor vehicle 1 and / or in a lower area of ​​a windshield and / or a rear window of the motor vehicle 1.Furthermore, at least some individual transmitting and receiving modules 3 can be arranged on the roof of the motor vehicle 1. The sketched positions of the individual transmitting and receiving modules 3 are examples. More, fewer, and / or differently arranged transmitting and receiving modules 3 are possible.

[0052] Alternatively or additionally, several transmit and receive modules 3 can be spatially distributed within the interior of the vehicle 1 (not shown here). These transmit and receive modules 3 can, for example, be located on the vehicle roof or headliner.

[0053] The radar system 2 comprises a central control unit 4. The central control unit 4 can, for example, provide control commands for the individual transmit and receive modules 3, provide signals for at least some of the transmit and receive modules 3 to be transmitted by means of the transmit and receive modules 3, and / or perform processing tasks. The radar system 2 always comprises only a single central control unit 4.

[0054] Fig. Figure 2 shows a method for operating a keyless access system 11 for a motor vehicle 1. The motor vehicle 1 has the radar system 2 described above. In a process step S1, at least one output signal 5 is generated by means of the central control unit 4 of the radar system 2. In a process step S2, the at least one generated output signal 5 is transmitted internally within the radar system to at least some of the transmitting and receiving modules 3. The transmission within the radar system is based at least partially on optical transmission techniques.

[0055] In process step S3, at least one output signal 5 is transmitted by means of at least part of the transmitting and receiving modules 3, after these have received the output signal 5 from the central control unit 4. The output signal 5 that is transmitted may correspond to the generated and transmitted output signal 5 or may differ from it, at least partially.

[0056] The method may include further process steps S4 to S6, which are carried out using a mobile device 6. The mobile device 6 is, for example, a smartphone, a tablet, a key, and / or another portable device. The mobile device 6 is assigned to the motor vehicle 1 and / or a user of the motor vehicle 1. The mobile device 6 may have at least one transmitting and / or receiving device 7 and a control unit 8. In process step S4, the mobile device 6 receives the transmitted output signal 5. In process step S5, a response signal 9 to the received output signal 5 can be generated using the mobile device 6, in particular using its control unit 8. In process step S6, the generated response signal 9 can be transmitted using the mobile device 6, in particular using its transmitting and / or receiving device 7.

[0057] In process step S7, at least one response signal 9 to the output signal 5 is received by means of at least a portion of the transmit and receive modules 3 of the radar system 2, or by means of at least the portion of the transmit and receive modules 3 that transmitted the output signal 5. In process step S8, the at least one received response signal 9 is transmitted internally within the radar system by at least that portion of the transmit and receive modules 3 to the central control unit 4 of the radar system 2. This internal transmission is again carried out at least partially using optical transmission techniques.

[0058] In process step S9, the control unit 4 checks whether the at least one received response signal 9 meets a predefined admissibility criterion 10. If this is the case, i.e., if the received response signal 9 meets the predefined admissibility criterion 10, then in process step S10, the operation of the keyless access system 11 using the mobile device 6 is permitted. If this is not the case, i.e., if the predefined admissibility criterion 10 is not met, then in process step S11, the operation of the keyless access system 11 using the mobile device 6 is prevented.

[0059] It can be provided that the output signal 5 is signal-coded and the received response signal 9 only fulfills the specified admissibility criterion 10 if it is correlated with the signal-coded output signal 5. For this purpose, it must, for example, have a signal coding 12 that is correlated with the signal-coded output signal 5, i.e., that matches the signal-coded output signal 5, and is thus taken into account when applying admissibility criterion 10. Alternatively or additionally, the central control unit 4 can determine a transit time 13 of the response signal 9 when checking it, and the specified admissibility criterion 10 can only be considered fulfilled if, by evaluating the determined transit time 13, it is established that the mobile device 6 is located in a specified area of ​​the motor vehicle 1.

[0060] It can be provided that at least one or a part of the transmitting and receiving modules 3 continuously receives response signals 9 from the mobile device 6. Using the central control unit 4, a relative arrangement determination criterion can be applied to the continuously received response signals 9 to determine the relative arrangement of the mobile device 6 to the motor vehicle 1, in particular a relative position and / or relative orientation. This can be used, for example, to check whether the mobile device 6 is arranged in a specified environment.

[0061] It can be verified whether the response signal 9 is received from outside the vehicle 1 or from inside the vehicle 1. If it is received from the vicinity of the vehicle 1, i.e., from outside, then, if the operation of the keyless access system 11 is permitted (i.e., after procedure step S10), at least one automatic unlocking or locking of at least one locking device of at least one door and / or trunk of the vehicle 1 is allowed. However, if the mobile device 6 is detected inside the vehicle 1 because the response signal 9 is received from inside the vehicle 1, then, for example, if the operation of the keyless access system is permitted (i.e., after procedure step S10), at least one engine start of the vehicle 1 is allowed using the mobile device 6.Starting the engine may also require, for example, the activation of a start-stop button in the vehicle 1, and thus the activation of an operating element in the vehicle 1. In connection with the authorized engine start, the position of the mobile device 6 in the interior can also be determined by applying a position determination criterion to the received response signal 9 using the central control unit 4, and it can be verified whether the determined position is located within the area of ​​a driver's seat in the vehicle 1. Only if this is the case is the engine start of the vehicle 1 authorized.

[0062] In one example, at least the output signal 5 is in the megahertz range, specifically between 400 megahertz and 900 megahertz. The response signal 9 can also be in the megahertz range or alternatively in the kilohertz, hertz, or gigahertz range.

[0063] The motor vehicle 1 together with the mobile device 6 can be understood as a system that can carry out the described procedure.

[0064] Fig. Figure 3 shows individual components of the radar system 2 for carrying out the described method in detail. Each of the several transmit and receive modules 3 of the radar system 2 comprises at least one transmit and / or receive antenna 30 and an antenna control unit 31. The antenna control unit 31 is preferably a chip for controlling, for example, the at least one transmit and / or receive antenna 30. In one example, the antenna control unit 31 is an electronically photonically cointegrated chip (EPIC).

[0065] Data transmissions based on optical transmission techniques, and thus involving optically encrypted data connections and / or signal transmissions, are depicted with dashed lines 32. All electronically coded signal transmissions via electronic channels are depicted with solid lines 33. Components shown with dashed boundaries are optical components, while those shown with solid boundaries are electronic components.

[0066] The central control unit 4 can include an optical transmitter 35 that provides the optically coded output signal 5 to the respective transmitter and receiver module 3 and couples it into the at least one optical fiber 34 as an optically coded output signal 5. The respective transmitter and receiver module 3 can include an optical receiver 36 that receives the optically coded output signal 5 and converts it into an electronically coded output signal 5. Based on the electronically coded output signal 5, the respective radar device 3 can emit electromagnetic waves into the vicinity of the motor vehicle 1 in accordance with the electronically coded output signal 5.

[0067] The respective transmit and receive module 3 can include an optical modulation unit 37, which can convert the at least one received response signal 9 into an optically coded response signal 9. The optically coded response signal 9 can be coupled into the at least one optical fiber 34. The central control unit 4 can include an optical receiver 51 and an evaluation unit 50. The optical receiver 51 can receive the optically coded response signal 9, and the evaluation unit 50 can evaluate it.

[0068] The electronic components of the radar system 2 include, for example, a control interface 38, an optional arbitrary waveform generator (AWG) 39 for laser modulation, a digital interface 40, in particular for an analog-to-digital converter (ADC), and / or a low-level signal processing unit 41 for performing a fast Fourier transform. Furthermore, an evaluation unit 50 can comprise at least one processing unit, in particular a central processing unit (CPU), a graphics processing unit (GPU), and / or a personal computer (PC) interface.

[0069] The optical components of the radar system 2 may include an optional feedback loop / control unit 42, a laser and / or jamming beam source module 43, a gigahertz frequency synthesis module 44, an optical control module 45, an optical switch 46 and / or an optical detection / homodyne / heterodyne detection unit 47, including phase and / or length measurement. Fig. Figure 3 also shows electronic output channels 48 to the antenna control units 31 and an electronic return channel 49.

[0070] The optically encoded output signal 5 can be generated by modulating the generated output signal 5 to a predetermined optical carrier frequency, in particular with a predetermined fraction of the frequency of the transmitted electromagnetic wave. Alternatively or additionally, the optically encoded response signal 9 can be generated by modulating the received response signal 9 to the predetermined optical carrier frequency, in particular with a predetermined fraction of the frequency of the received response signal 9.

[0071] The central control unit 4 can generate the optical carrier signal. This signal is fed into the gigahertz frequency synthesis module 44, and the synthesized gigahertz signal is transmitted in the optical spectral range via the fiber optic cable 34 to the antenna control unit 31 (EPIC chips) to be transmitted, for example, as a gigahertz or megahertz signal. Signal detection is performed in reverse. All data is processed in the central control unit 4.

[0072] Overall, the examples demonstrate a photonic radar (radar system 2) for a keyless entry system 11 of a motor vehicle 1. The photonic radar, i.e., the described radar system 2, which can actually be used for environmental sensing or interior monitoring, can be used to operate a keyless entry system 11 without complex hardware modifications. The evaluation of the response signal 9 takes place in the central control unit 4. The radar system 2 can be used for communication with the mobile device 6. Depending on the frequency band of the keyless entry system 11 used, an exact position of the mobile device 6 relative to the motor vehicle 1 can be determined. For this purpose, for example, a round-trip time between the generation of the output signal 5 and the reception of the response signal 9 is evaluated in order to precisely determine, for example, the distance of the mobile device 6 to the motor vehicle 1.This allows measures to be taken to prevent relay attacks.

[0073] The radar system 2 utilizes the cointegration of electronic and photonic components within a single semiconductor. It generates a so-called FMCW signal (FMCW stands for frequency modulated continuous wave), with all signal processing and evaluation being performed by the central control unit 4. Individual transmit and receive modules, i.e., the individual transmit and receive modules 3, comprise an electronically-photonically cointegrated chip, which can be referred to as an EPIC chip. Silicon photonics technology can be used for this cointegration. This technology enables the monolithic integration of photonic components, high-frequency electronics, and digital electronics onto a single chip. This can be described as electronic-photonic cointegration.This enables signal transmission of gigahertz signals using an optical trigger signal in the terahertz frequency range, for example, to use radar system 2 for radar measurement. The central control unit 4 generates the optical carrier frequency in the terahertz range. The signal to be transmitted is modulated onto this carrier frequency at 1 / 8 of the desired radar frequency (for example, in the case of radar operation) and sent to the individual antennas, and thus to the individual transmit and receive modules 3, via optical phase correction. These modules perform an eightfold frequency amplification, so that the radar radiation, i.e., electromagnetic waves, can be imitated by the transmit and receive modules 3. The detection of a signal, the response signal 9, occurs in reverse.

[0074] The method described above has the advantage that a large number of antennas, which are usually required for keyless access systems 11 in the motor vehicle 1, can be dispensed with, since the radar system 2 is used. Instead of gigahertz signals required for radar technology, the central control unit 4 generates the output signal 5 in the megahertz range. This is transmitted via the fiber optic cables to the individual transmit and receive modules 3 and broadcast from there. The individual transmit and receive modules 3 receive the response signal 9 transmitted by the mobile device 6 and forward it to the central control unit 4, which can evaluate the output signals 5 and validate them with regard to encryption (signal coding) or other criteria, i.e., check whether the admissibility criterion 10 is met or not.

[0075] The numerous transmitting and receiving modules 3 inside and / or outside the vehicle 1 enable, for example, precise localization of the mobile device 6 and thus the same functionality as known keyless entry systems 11 that are not based on the described radar system 2. Software adjustments can already make it possible to generate and / or adapt any desired output signals in the central control unit 4. This allows for easy adaptation to other types of mobile devices 6, such as smartphones or smart keys. Furthermore, field strength and / or signal propagation time differences between the individual transmitting and receiving modules 3, as well as the angle at which the response signal 9 reaches the transmitting and receiving modules 3, can be used for position determination. This makes the radar system 2 comparable to a passive transmitting and receiving module 3.The prerequisite is that the position of each individual transmitting and receiving module 3 is precisely known. It is generally irrelevant whether the response signal 9 is sent by a smart key or a smartphone. Mobile devices 6 based on ultra-wideband signals can also be integrated. Reference symbol list 1 motor vehicle 2 radar systems 3 Transmit and receive module 4 central control unit 5 Output signal 6 mobile device 7 Receiving equipment 8 Control unit 9 Response signal 10 Admissibility criteria 11 keyless access system 12 Signal coding 13 runtime 30 Transmitting and / or receiving antennas 31 Antenna control unit 32 dashed line 33 continuous line 34 fiber optic cables 35 optical transmitter unit 36 optical receiving units 37 optical modulation unit 38 Control interface 39 Arbitrary Waveform Generator 40 interface 41 Low-level signal processing unit 42 Feedback loop / control unit 43 Interference Source Module 44 Gigahertz Frequency Synthesis Module 45 Control module 46 switches 47 Detection / homodyne / heterodyne detection unit 48 output channels 49 Return channel 50 evaluation units 51 optical receiving unit

Claims

[1] Method for operating a keyless access system (11) for a motor vehicle (1), wherein the motor vehicle (1) comprises a radar system (2) comprising several spatially distributed individual transmit and receive modules (3) and a central control unit (4), wherein the radar system (2) uses at least partially optical transmission techniques for the radar system-internal transmission of signals between the individual transmit and receive modules (3) and the central control unit (4), wherein the method comprises: - Generating at least one output signal (5) by means of the central control unit (4); - radar system internal transmission of at least one output signal (5) to at least one part of the transmit and receive modules (3); - Emitting at least one output signal (5) by means of at least part of the transmit and receive modules (3); - Receiving at least one response signal (9) to the output signal (5) emitted by a mobile device (6) assigned to the motor vehicle (1) and / or a user of the motor vehicle (1) and which has received the emitted output signal (5), by means of at least one part of the transmit and receive modules (3); - radar system internal transmission of at least one received response signal (9) to the central control unit (4); - Check whether at least one received response signal (9) meets a predefined admissibility criterion (10) using the central control unit (4); and - if at least one received response signal (9) meets a specified admissibility criterion (10), allowing the operation of the keyless access system (11) by means of the mobile device. [2] Method according to claim 1, wherein the output signal (5) is signal-coded and the received response signal (9) only meets the specified admissibility criterion (10) if the received response signal (9) is correlated with the signal-coded output signal (5). [3] Method according to one of the preceding claims, wherein the central control unit (4) determines a transit time (13) of the response signal (9) when checking the received response signal (9) and the specified admissibility criterion (10) is only fulfilled if, by evaluating the determined transit time (13), it is established that the mobile device (6) is arranged in a specified environment of the motor vehicle (1). [4] Method according to one of the preceding claims, wherein response signals (9) are continuously received from the mobile device (6) by means of at least part of the transmitting and receiving modules (3), wherein a relative arrangement of the mobile device (6) to the motor vehicle (1) is determined by means of the central control unit (4) by applying a relative arrangement determination criterion to the continuously received response signals (9), wherein the predetermined admissibility criterion (10) is only fulfilled if the mobile device (6) is arranged in a predetermined environment of the motor vehicle (1) according to its relative arrangement. [5] Method according to one of the preceding claims, wherein it is checked whether the response signal (9) is received from outside the motor vehicle (1), wherein, if the response signal (9) is received from outside the motor vehicle (1), in the case of allowing the operation of the keyless access system (11) by means of the mobile device (6), at least one automatic unlocking and / or locking of at least one locking device of a door and / or trunk of the motor vehicle (1) is permitted. [6] Method according to one of the preceding claims, wherein it is checked whether the response signal (9) is received from an interior of the motor vehicle (1), wherein, if the response signal (9) is received from the interior of the motor vehicle (1), in the case of allowing the operation of the keyless access system (11) by means of the mobile device (6), at least one engine start of the motor vehicle (1) is permitted. [7] Method according to claim 6, wherein a position of the mobile device (6) in the interior is determined by applying a position determination criterion to the received response signal (9) by means of the central control unit (4) and it is checked whether the determined position is located in an area of ​​a driver's seat of the motor vehicle (1), wherein only if the determined position is located in an area of ​​a driver's seat of the motor vehicle (1) is the engine start of the motor vehicle (1) permitted. [8] Method according to any of the preceding claims, wherein at least the output signal (5) is between 400 megahertz and 900 megahertz. [9] Motor vehicle (1) with a radar system (2) comprising several spatially distributed individual transmit and receive modules (3) and a central control unit (4), wherein the radar system (2) uses at least partially optical transmission techniques for the radar system-internal transmission of signals between the individual transmit and receive modules (3) and the central control unit (4), wherein the motor vehicle (1) is configured to perform a method according to one of the preceding claims. [10] System comprising a motor vehicle (1) according to claim 9 and a mobile device (6) with at least one transmitting and / or receiving device (7), wherein the system is configured to perform a method according to any one of claims 1 to 8.

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