VEHICLE COMMUNICATION SYSTEM

Description

[0001] The invention relates to a communication system for a vehicle. The communication system serves, in particular, for communication between the vehicle and a portable ID transmitter, which is configured, in particular, for UWB communication. The communication that can be performed with the communication system is suitable for contributing to the release of vehicle functions for an operator if the operator carries the portable ID transmitter with them.

[0002] Various access systems based on radio technology are known from the state of the art. These are often referred to as keyless access systems because they operate without mechanical key bits. Keyless access systems of this type are based on radio communication between a vehicle-based infrastructure and a portable ID transmitter. During the radio communication, an authorized ID transmitter authenticates itself to the vehicle-based infrastructure. The ID transmitter is typically authenticated using cryptographic methods, particularly through the exchange and verification of encrypted authorization data.

[0003] In the field of keyless entry systems, the use of low-frequency (LF) and high-frequency (HF) radio waves is well-known and common. Combined communication using LF / HF systems is also known in practice. For example, the ID transmitter is first woken up with an LF wake-up signal, after which the actual authentication is performed via HF communication.

[0004] In radio-based authorization systems, security is of crucial importance, especially with regard to the compromise of the radio communication carried out.

[0005] A threat to the security of radio-based authentication systems is the fundamental disadvantage that LF or HF radio communication is protracted. One type of attack scenario based on forwarding LF or HF radio communication is known as relay station attacks.

[0006] Such prior art is disclosed, for example, in the documents WO 2017 / 191480 A1, WO 2017 / 144345 A1 and US 2014 / 0330449 A1.

[0007] Given the increasing importance of keyless entry systems and the above explanations, there is a desire to provide communication between ID transmitters and a vehicle with improved security against compromise.

[0008] The object of the invention is to provide a concept on the basis of which authentication of an ID transmitter on a vehicle can be carried out with improved security.

[0009] The problem is solved by a communication system having the features of patent claim 1.

[0010] The communication system comprises at least a first UWB receiver and a second UWB receiver.

[0011] The communication system contributes to the secure release of vehicle functions by providing a vehicle authentication system with information about whether a UWB communication between the ID transmitter and the vehicle can be considered authentic communication.

[0012] Depending on the overall design of the vehicle, the communication system can be viewed either as part of the authentication system or as a system independent of the authentication system.

[0013] The first UWB receiver comprises a first UWB antenna, and the second UWB receiver comprises a second UWB antenna. It is conceivable for a UWB receiver and a UWB antenna to be part of a compactly provided module, for example, a UWB transceiver. Alternatively, it is conceivable for a UWB antenna to be coupled to, but spaced from, the remaining components of a UWB receiver.

[0014] The first UWB antenna and the second UWB antenna are arranged at a distance from each other on the vehicle.

[0015] The spaced-apart arrangement of the UWB antennas on the vehicle is to be understood as meaning that the distance between the UWB antennas is greater than an immediately adjacent arrangement of UWB antennas, for example, the distance is at least two centimeters. It is essential that the first and second UWB antennas are arranged at different positions on the vehicle and that the distance between the UWB antennas is large enough that, upon reception of the same signal, it results in a propagation time difference between the signal from its transmission source to the first UWB antenna and the signal from its transmission source to the second UWB antenna that can be detected and / or evaluated by the communication system.

[0016] All UWB receivers are coupled to a central UWB control unit in the vehicle. A separate unit can be provided as the UWB control unit, but the vehicle's central control unit or a part of the vehicle's central control unit can also be configured as the UWB control unit.

[0017] The communication system is configured for UWB communication with a predetermined ID transmitter or a number of predetermined ID transmitters, but the ID transmitter itself is not a component of the communication system according to the invention.

[0018] The central UWB control unit is configured to evaluate both a first received signal of an ID transmitter UWB signal received by the first UWB antenna and a second received signal of the same ID transmitter UWB signal received by the second UWB antenna in dependence on one another for authentication of the communication of the vehicle with the ID transmitter.

[0019] In other words, both the first UWB antenna and the second UWB antenna receive the same UWB signal transmitted by the ID transmitter (namely, the ID transmitter UWB signal). Authentication of the vehicle's communication with the ID transmitter is based on both the received signal received at the first UWB antenna and the received signal received at the second UWB antenna. This means that, based on the same transmitted ID transmitter UWB signal, both a received characteristic at the first UWB antenna and a received characteristic at the second UWB antenna are detected. Both received characteristics are evaluated jointly by the central UWB control unit to authenticate the vehicle's communication with the ID transmitter.

[0020] In principle, the use of ultra-wideband radio signals, abbreviated to UWB radio signals, is well known in practice. However, it has only recently become accessible for use in a wide range of applications, not least due to more liberal regulation. As a result, UWB transceivers that can be universally implemented in applications are now commercially available.

[0021] Ultra-wideband technology is a type of radio communication based on the transmission of short signal pulses. The signal pulses cover a multitude of frequencies within a comparatively large frequency bandwidth. The width of the covered frequency ranges is limited or dependent, not least, on the regulatory requirements of the respective territorial area. In order to make ultra-wideband communication usable without disrupting other radio communications, the transmission powers used are generally comparatively low due to regulatory requirements, which is why ultra-wideband technology, in the sense described here, is short-range radio communication. UWB radio communication can, for example, take place in a frequency range between 30 MHz and 30 GHz.

[0022] In UWB, information transmission is not based on carrier frequency modulation. Instead, other modulation methods are used, such as on / off keying, pulse amplitude modulation, or pulse position modulation.

[0023] UWB communication has the fundamental advantage over other radio communications, such as LF communication, that, due to the transmission of pulses having a variety of frequencies, reliable distance determination is possible using a time-of-flight approach. This is often referred to as time-of-flight distance determination. For example, the distance between a vehicle's UWB antenna and a portable ID transmitter configured for UWB communication can be determined by sending a UWB signal from the vehicle's UWB antenna to the portable ID transmitter. A UWB transceiver of the portable ID transmitter responds to this signal. After the response signal is received by the vehicle's UWB antenna, a control device coupled to the vehicle's UWB antenna evaluates the measured time-of-flight.In this example, the distance to the ID transmitter, a response time within the ID transmitter, and the distance from the ID transmitter to the vehicle's UWB antenna are taken into account. If, as in this example, the propagation time is evaluated on the vehicle side, only the response time within the ID transmitter needs to be known on the vehicle side, so that a corresponding correction can be made to the time measured on the vehicle side between the transmission of the UWB signal and the reception of the UWB response.

[0024] Experience has shown that the accuracy of such a UWB-based distance determination is significantly higher than that of many other methods at the typically intended ranges. UWB-based distance determination is generally more accurate than distance determination based on signal strength determination of LF signals or triangulation of LF signals. Under good conditions, the accuracy of UWB-based distance determinations is on the order of ten to twenty centimeters.

[0025] A major advantage of using UWB signals is that, due to the large number of frequencies used, complete signal obscuration is very unlikely. This is because, with a very high probability, there is always a line of sight between the transmitter and receiver for at least some of the frequencies used simultaneously. Due to the large number of different frequencies used, diffraction effects and / or reflections can be expected in most cases for at least some of the frequencies used.

[0026] The present invention exploits the fact that the detection of the same ID transmitter UWB signal with at least two UWB antennas, namely at least the first UWB antenna and the second UWB antenna, with subsequent evaluation by the central UWB control unit, can contribute to the secure authentication of the vehicle's communication with the ID transmitter. In particular, the authentication of the communication between the ID transmitter and the vehicle can be provided as a prerequisite for enabling a vehicle function, so that enabling a vehicle function is only possible under the condition that the communication between the ID transmitter and the vehicle is not discarded as non-authentic communication.In particular, the central UWB control unit can evaluate whether the first received signal and the second received signal can be transmitted simultaneously by the same ID transmitter, taking into account the distance between the first UWB antenna and the second UWB antenna (which is known to the central control unit). The precise design of this evaluation is subject to expert practice. In one variant, the evaluation can include, in particular, the distance between the first UWB antenna and the second UWB antenna, taking into account that the reception of the ID transmitter UWB signal at the first UWB antenna and the reception of the ID transmitter UWB signal at the second UWB antenna can have at most a transmission-related propagation time difference that corresponds to the distance between the UWB antennas.

[0027] Because the first UWB antenna and the second UWB antenna are spaced apart from each other, the UWB control unit, with appropriate configuration, can incorporate into the evaluation the fact that, based on the sequence of UWB antennas that consecutively receive the same received signal, the positioning of the ID transmitter can be restricted to a corresponding subspace. For example, in a communications arrangement with two UWB antennas, it can be concluded that the ID transmitter is located in a half-space that also contains the one of the two UWB antennas that first received the ID transmitter UWB signal.

[0028] Alternatively or additionally, when setting up the central control unit for evaluating the received signals, knowledge of the directional dependence of the reception sensitivities of the UWB antennas can be incorporated. This means, for example, that the differences in the detected intensities can be evaluated taking into account the different orientations of the UWB antennas, which are known to the central UWB control unit.

[0029] The authentication of the ID transmitter on the vehicle, i.e., the verification of whether vehicle functions can be authorized for an operator carrying the portable ID transmitter, can be performed in any manner using a vehicle authentication system based on communication with the ID transmitter after ensuring that the communication can be considered authentic, i.e., assuming the communication has been successfully authenticated. Known methods such as an exchange of cryptographic information between the authentication system and the ID transmitter can be used for this purpose. The exchange of cryptographic information can be performed, for example, via UWB communication between the ID transmitter and one of the UWB antennas or via RF communication between an RF interface of the ID transmitter and an RF interface of the authentication system.The exchange of cryptographic information can be carried out independently of the communication between the ID transmitter and the vehicle described above, for example, before or after the communication, as part of a dedicated UWB and / or RF communication. Alternatively, the exchange of cryptographic information can be carried out entirely or partially as part of the communication between the ID transmitter and the vehicle described above, i.e., using the ID transmitter's UWB signal.

[0030] The ID transmitter UWB signal can, for example, be a signal used to determine the distance between one of the UWB antennas and the vehicle. Alternatively or additionally, the ID transmitter UWB signal can be a signal used to transmit cryptographic information for authenticating the ID transmitter on the vehicle. Alternatively, the ID transmitter signal can also be transmitted specifically for the purpose of confirming the authenticity of the communication, with the authentication of the ID transmitter on the vehicle being performed in addition to the verification of the authenticity of the communication, for example, with a separate UWB communication or with an RF communication between an RF interface of the ID transmitter and an RF interface of the authentication system.

[0031] According to the invention, it is provided for the design of the communication system that the direction of a maximum reception sensitivity of the first UWB antenna and the direction of a maximum reception sensitivity of the second UWB antenna are oriented at an angle to each other which is at least 30 degrees.In other words, UWB antennas with a certain directional characteristic are used as part of the communication system; the directional characteristic is taken into account when positioning the UWB antennas on the vehicle in such a way that the directions for maximum reception sensitivity are oriented at an angle to one another, so that, for example, a half-line directed from the first UWB antenna in the direction of the maximum reception sensitivity of the first UWB antenna and a half-line directed from the second UWB antenna in the direction of the maximum reception sensitivity of the second UWB antenna are oriented at an angle to one another of at least 30 degrees.

[0032] The deviation of the maximum reception sensitivities influences the received signal strengths accordingly.

[0033] According to a further embodiment of the invention, it can be provided that the direction of the maximum reception sensitivity of the first UWB antenna and the direction of the maximum reception sensitivity of the second UWB antenna are oriented at an angle to each other that is at most 120 degrees.

[0034] In a preferred embodiment of the communication system, the selection and positioning of the UWB antennas relative to each other is selected such that an overlap zone exists in front of a driver's door of the vehicle. Within the overlap zone, the reception sensitivity of the first UWB antenna and the reception sensitivity of the second UWB antenna exceed a minimum value at every location, which is in any case greater than zero.

[0035] In particular, an extension of the overlap space, the selection, positioning and orientation of the UWB antennas, as well as the selection of a UWB communication arrangement of the ID transmitter selected to be matched to one another such that for an ID transmitter located within the overlap space, UWB communication can be carried out with both the first UWB antenna and the second UWB antenna.

[0036] In other words, the communication system is configured by appropriately selecting and positioning the UWB antennas such that an ID transmitter can conduct UWB communication with both the first UWB antenna and the second UWB antenna when the ID transmitter is located at a designated location. The designated location or locations are defined as such by the vehicle manufacturer, for example, and are covered by an overlapping area of ​​two or more UWB antennas. The targeted formation of one or more overlapping areas ensures that the interdependent evaluation of the first received signal and the second received signal can be carried out by the central UWB control unit.

[0037] The targeted use of UWB antennas with a directional characteristic and the targeted provision of overlap areas offer the advantage that the UWB communication between the ID transmitter and the vehicle is locally restricted to one or more regions within which the ID transmitter is expected to be located during a typical operating scenario. The certain directional characteristic—in other words, anisotropic reception sensitivity—that is inherent in many UWB antennas is thus used in a particularly elegant and preferential manner to provide communication whose compromise-resistance is already achieved due to the design-related limited local shape of the overlap areas.

[0038] A further advantage of using UWB antennas with a directional pattern is that any distortion of a UWB time-of-flight measurement, for example, due to reflections, can be detected. The reason for this is that with UWB antennas with a directional pattern and when the UWB antennas are positioned at an angle to each other, the probability that a reflected ID transmitter UWB signal will be received by multiple UWB antennas is low. Thus, with a certain probability, a reflected signal will lead to a time-of-flight difference between the time-of-flight values ​​recorded at different UWB antennas that is greater than the maximum time-of-flight explained below.

[0039] According to one embodiment, communication between the ID transmitter and the vehicle is discarded as inauthentic communication if only one of the UWB antennas registers a received signal from the ID transmitter's UWB signal. In such a case, it cannot be guaranteed that the signal has not been manipulated. However, if reception is only possible with one UWB antenna, it can be concluded that the operator is most likely not located in an overlap area designated by the vehicle provider as the operator's position when the position is released.

[0040] Alternatively or additionally, according to an advantageous embodiment, the UWB control unit is configured to evaluate a first propagation time value of the first received signal and a second propagation time value of the second received signal using N-lateration, where N is the number of UWB antennas that detect a received signal of the same ID transmitter UWB signal. For example, if two UWB antennas are present, this means that bilateration is performed to evaluate the first propagation time and the second propagation time. If three UWB antennas are present and detect a received signal, trilateration is performed, and so on.

[0041] To evaluate the propagation time of a UWB signal, a vehicle UWB signal is preferably first sent to the ID transmitter. The ID transmitter then sends the UWB signal in response. This enables a vehicle-side control unit, for example, the UWB control unit, to evaluate the UWB communication over the entire path from vehicle to ID transmitter to vehicle. Particularly preferably, one of the UWB antennas provided according to the invention is used to transmit the vehicle UWB signal.

[0042] According to the invention, the UWB control unit is configured such that the evaluation of the first received signal and the second received signal in dependence on one another comprises that a first propagation time value of the first received signal and a second propagation time value of the second received signal are determined and the communication of the vehicle with the ID transmitter is rejected as non-authentic communication if an amount of a propagation time difference between the first propagation time value and the second propagation time value exceeds a maximum propagation time by more than a tolerated deviation.

[0043] According to one variant, communication between the vehicle and the ID transmitter is rejected as non-authentic communication if the amount of the runtime difference between the first runtime value and the second runtime value exceeds the maximum runtime by more than the tolerated deviation, and in the other case, the communication between the vehicle and the ID transmitter is accepted as authentic, i.e. non-corrupted, communication, and the authentication of the communication is therefore considered successful.

[0044] According to one variant, it can be provided that the authentication of the communication is only considered successful if additional conditions are met, whereby the expert can provide a number of further verification instances.

[0045] The maximum propagation time is the time required for electromagnetic waves to travel the distance between the first UWB antenna and the second UWB antenna. This exploits the trigonometric principle that the path difference of the same UWB signal from the ID transmitter to two spaced-apart UWB antennas, for all possible positions of the ID transmitter, corresponds at most to the distance between the two UWB antennas.In other words: The propagation times, or alternatively or additionally the reception times, at the position of the first UWB antenna and the position of the second UWB antenna are compared, and the difference between the two is checked to determine whether they are plausible given the distance between the first UWB antenna and the second UWB antenna. This means that a propagation time difference between a propagation time at the first UWB antenna and a propagation time at the second UWB antenna corresponds at most to the distance between the first and second UWB antennas. In order to mitigate potential computing times or inaccuracies in the recording of the times or their electronic processing, one variant provides for a tolerated deviation. The tolerated deviation defines a tolerance range and can, for example, be 20 percent of the minimum propagation time, which is permitted in addition to the maximum propagation time.

[0046] The propagation time of the received signal can be set to "time of transmission of the query signal from the transmitting UWB antenna -> response with ID transmitter UWB signal by ID transmitter -> time of reception by the receiving UWB antenna".

[0047] The propagation time of the received signal can be set to "ID transmitter UWB signal through ID transmitter -> time of reception by receiving UWB antenna".

[0048] Alternatively, the time of reception of the ID transmitter UWB signal at the respective receiving UWB antenna can be provided as the transit time value.

[0049] Because the propagation time values ​​are determined with reference to two spaced-apart UWB antennas, but based on the reception of the same signal, namely the ID transmitter UWB signal, all of the above-mentioned variants of the propagation time value are equivalent and, if a difference is formed, result in the same propagation time difference, at least in an ideal scenario. Any minor deviations from the ideal scenario, for example, due to device-related factors, can be taken into account in the actual implementation of the invention with the intended tolerated deviations.

[0050] According to a preferred embodiment of the communication system, the UWB control unit is configured, as part of the evaluation of the first received signal and the second received signal in dependence on one another to determine a propagation time value for each of the received signals and to calculate a propagation time average from the determined propagation time values, and / or to determine a signal strength value, for example an RSSI value, for each of the received signals and to calculate a signal strength average from the determined signal strength values, wherein a UWB distance value average is derived from the average transit time and / or the average signal strength. The average distance value is preferably an average of the determined distances, wherein the distance of the ID transmitter to each of the UWB antennas that have detected a received signal is determined via the transit time of the UWB signal. Preferably, only one of the existing UWB antennas is used to transmit a requesting UWB signal, so that the transit time on the way to the ID transmitter is the same and only the transit time of the ID transmitter UWB signal on the way from ID transmitter to the respective UWB antenna is different. Since the UWB control unit knows which of the UWB antennas the request signal was sent from, the UWB control unit can determine the distance of the ID transmitter for each received signal, as long as one of the receiving UWB antennas also sent the requesting signal. Preferably, the request is repeated until the requesting antenna has also detected a received signal. Alternatively, the distance can also be determined from the propagation time "requesting antenna -> ID transmitter -> receiving antenna" for different receiving antennas but the same requesting antenna. The inaccuracy in the distance determination resulting from repeatedly considering the requesting antenna is neglected, as it is considered negligible compared to the distance determination accuracy using other methods, for example, using LF signal strengths.Independently of this, an LF distance value is determined from a signal strength, for example, an RSSI signal strength, of a detected LF signal from the ID transmitter using an LF receiver unit in the vehicle and transmitted to the UWB control unit. The LF receiver unit is coupled to the UWB control unit and can either be part of the communication system or not be part of the communication system. The vehicle's communication with the ID transmitter is rejected by the UWB control unit as non-authentic communication if the LF distance value and the UWB distance value mean deviate from each other beyond a tolerated maximum deviation. In other words, distance information based on LF signal strength, which is generally less accurate than a UWB distance determination, is compared with distance information derived from the UWB communication.The comparison contributes to the authentication of communication between the ID transmitter and the vehicle by checking the consistency of the determined distance information. This is because both the LF signal strength and the LF signal strength are measured. Since both distance values ​​based on a UWB propagation time and distance values ​​based on a UWB propagation time are recorded, compromising communication is only possible with great effort, if at all. By taking into account an average of distance values ​​from all UWB antennas receiving a UWB signal, the potential influence of any reflections of individual waves of the UWB signal is reduced.

[0051] It can be provided that the communication between the vehicle and the ID transmitter is considered authentic if and only if it is not rejected as inauthentic according to one or more of the above procedures. Alternatively, additional verification instances can be provided.

[0052] The tolerated maximum deviation can be, for example, 30 percent, preferably 10 percent, of the calculated UWB distance value mean.

[0053] According to a further preferred embodiment of the communication system, the first UWB antenna is arranged in a first handle on a driver's door of the vehicle. Alternatively or additionally, the second UWB antenna is arranged in a second handle on a passenger door of the vehicle. The arrangement of one or more UWB antennas within a handle of a vehicle door handle has the advantage that the UWB antenna is elegantly arranged outside the vehicle's sheet metal casing. This results in more energy-efficient and qualitatively improved UWB communication. Arranging the UWB antenna on the vehicle door handle or within the vehicle door handle achieves the further advantage that an operator seeking access to the vehicle generally moves towards the driver's door handle to do so.Due to the typical operating situation, good conditions are expected for radio communication between the ID transmitter, which is in the possession of the operator, and the UWB interface.

[0054] The arrangement of the UWB antennas within the handles also has the advantage of a wide spacing of the UWB antennas on the vehicle, resulting in a comparatively large time difference between the times of reception of the UWB signal at the UWB antennas present in the different handles, with the advantage of a smaller relative error in the determination of the time difference.

[0055] Last but not least, if the UWB antenna is arranged within a handle, the electronics already present in modern handles can be used, which results in a cost advantage.

[0056] Preferably, the UWB antenna and the UWB receiver are part of a UWB transceiver. This has the advantage of simple and cost-effective implementation.

[0057] Preferably, the communication system has at least three, particularly preferably exactly four, spaced-apart UWB antennas.

[0058] Particularly preferably, the communication system comprises four UWB antennas spaced apart from one another, wherein the directions of maximum reception sensitivity are each oriented perpendicular to one another and parallel to a driving plane of the vehicle, preferably also lying in one plane.

[0059] One idea of ​​the invention relates to an authorization system comprising an ID transmitter and a communication system, wherein the ID transmitter and the communication system are configured for UWB communication with each other in accordance with the above explanation.

[0060] Further details, features, and advantages of the subject matter of the invention will become apparent from the following description taken in conjunction with the drawings. The drawings illustrate an exemplary embodiment of the invention.

[0061] It is understood that the features mentioned above and explained below can be used not only in the combination specified, but also in other combinations or on their own.

[0062] They show: Fig. 1 : A schematic diagram of a communication system according to the invention; Fig. 2 : Another schematic diagram of the communication system according to the invention of Fig. 1 .

[0063] Fig. 1 1 shows an exemplary embodiment of a communication system 1. The individual structural components of the communication system 1 are arranged on a vehicle 2. The communication system 1 enables the vehicle 2 to at least communicate via UWB using a portable ID transmitter 3. UWB communication serves, for example, to enable vehicle functions for an operator 4 who carries the ID transmitter 3 with them. The ID transmitter 3 is portable, meaning that the operator 4 can carry it without any aids. The ID transmitter 3 is also configured for UWB communication. The ID transmitter 3 therefore has communication means that enable the ID transmitter 3, among other things, for UWB communication. For example, these communication means can be a UWB transceiver 5 having a UWB antenna. The ID transmitter 3 is not a component of the communication system 1 of the present invention.However, ID transmitter 3 and communication system 1 are configured for UWB communication with each other, which means that all necessary hardware and software requirements are met so that operator 4 can authenticate himself as authorized to grant functions on the vehicle using ID transmitter 3 by using UWB communication between ID transmitter 3 and communication system 1.

[0064] The communication system 1 has a first UWB receiver 6, which is coupled to a first UWB antenna 7. Furthermore, a second UWB receiver 6' with a second UWB antenna 7' and two further UWB receivers 6", 6‴, each with a further UWB antenna 7", 7‴, are arranged on the vehicle. The UWB antennas 7, 7', 7", 7‴ are arranged at a distance from one another on the vehicle 2. In particular, in the embodiment shown, the first UWB antenna 7 is arranged in a first handle on a driver's door 8, and the third UWB antenna 7" is arranged in a second handle on a passenger door 9. The handles are not shown due to the schematic representation.

[0065] The UWB receivers 6, 6', 6", 6‴ are coupled to a central UWB control unit 10 of the vehicle 2, wherein the coupling is implemented via a wired connection in the example shown. The central UWB control unit 10 of the vehicle 2 is, in the illustrated embodiment, a component of a central control unit 11 of the vehicle 2. However, it is also conceivable for the UWB control unit 10 to be implemented as a separate unit from the central control unit 11.

[0066] When operator 4 approaches the vehicle, authentication of operator 4 is performed as a prerequisite for enabling functions of vehicle 2 for operator 4. This initially occurs, for example, according to a procedure known from practice. One such known procedural sequence provides, for example, that a low-frequency LF wake-up signal is first transmitted by vehicle 2. The LF wake-up signal switches ID transmitter 3, which is configured to receive LF wake-up signals, from a power-saving mode to an active mode. In response to the LF wake-up signal, ID transmitter 3 initiates UWB communication with vehicle-side control unit 11. UWB communication takes place via UWB transceiver 5 of ID transmitter 3.During UWB communication between the ID transmitter 3 and the vehicle-side control unit 11, for example, encrypted information is exchanged and verified by the other communication partner involved. Alternatively, it is also conceivable that the UWB communication is initiated by the vehicle-side central control unit 11 or by the UWB control unit 10 in response to an LF or HF request from the ID transmitter.

[0067] During UWB communication, the ID transmitter 3 transmits an ID transmitter UWB signal 12. In many cases, the ID transmitter UWB signal 12 is the response to a vehicle UWB signal. Both the first UWB antenna 7, which is coupled to the first UWB receiver 6, and the second UWB antenna 7', which is coupled to the second UWB receiver 6', receive the ID transmitter UWB signal 12. The first received signal of the ID transmitter UWB signal 12 received by the first UWB receiver 6 and the second received signal of the ID transmitter UWB signal 12 received by the second UWB receiver 6' are transmitted to the central UWB control unit 10. The central UWB control unit evaluates both signals together for plausibility.

[0068] In Fig. 2The boundary lines of the reception capability of the first UWB antenna 13, the second UWB antenna 13`, the third UWB antenna 13'', and the fourth UWB antenna 13‴ are shown. Outside the shown boundary lines, UWB communication between the specific ID transmitter 3 and the specific UWB antenna is no longer possible; the course of the boundary lines therefore always depends on the specific design of the individual components of the communication system 1 and the ID transmitter, whereby the communication system is configured for use with a correspondingly suitable ID transmitter. The point of reception capability furthest from the UWB antenna defines the direction of maximum reception sensitivity, starting from the respective UWB antenna. These directions are symbolized by the arrows 14, 14', 14", 14‴.It can be seen that the UWB antennas 7, 7', 7'', 7‴ have a pronounced directional characteristic, with the direction of maximum reception sensitivity in the illustrated embodiment being an axis of symmetry of a main lobe of the respective UWB antenna 7, 7', 7'', 7‴. In the illustrated embodiment, the directions of maximum reception sensitivity of two adjacent UWB antennas are oriented perpendicular to each other due to the selection of the UWB antennas, the orientation of the UWB antennas, and their positioning on the vehicle.

[0069] Furthermore, it can be seen that two adjacent UWB antennas in the illustrated embodiment each provide an overlap space. For example, the regions with a minimum reception sensitivity of the first antenna 7 and the second antenna 7' form an overlap space 15, within which both the first UWB antenna 7 and the second UWB antenna 7' can receive a transmitted UWB signal from the ID transmitter 3. In other words, as a result of the selection, positioning, and orientation of the UWB antennas as well as the selection of a UWB communication arrangement of the ID transmitter within the overlap space 15, UWB communication between the ID transmitter 3 and the vehicle 2 is possible via both the first UWB antenna 7 and the second UWB antenna 7'.Of course, the selection, positioning, and orientation of the antennas can be modified by the person skilled in the art. For example, orientations, selection, and positioning can also be provided where overlap spaces exist within which communication with all existing UWB antennas is possible. According to the above explanations, the specific dimensioning of the overlap space depends both on the specific type and positioning of the UWB antennas and on the selection of the ID transmitter. However, since the authorized ID transmitter 3 must be known to the vehicle 2 anyway, the person skilled in the art can select and position the UWB antennas, as well as control them, knowing one or more types of ID transmitters, without this presenting any particular difficulty.

[0070] Because UWB communication of the ID transmitter 3 is possible within the overlap space 15 with both the first UWB antenna 7 and the second UWB antenna 7', both a first received signal of the ID transmitter UWB signal 12 and a second received signal of the ID transmitter UWB signal 12 are provided to the central UWB control unit 10. The central UWB control unit 10 is thereby enabled to evaluate the received ID transmitter UWB signal 12 for its authenticity according to its configuration and to consider both the first and second received signals of the same ID transmitter UWB signal 12 during the evaluation.

[0071] In the illustrated embodiment, the overlap space 15 is adapted by the person skilled in the art entrusted with providing the subject matter according to the invention in such a way that communication of the ID transmitter UWB signal with the first UWB antenna 7 and the second UWB antenna 7' is possible at a position of the operator 4 which the operator assumes when approaching the driver's door 8. A narrowly defined limitation of the overlap space 15 is not important as long as it is ensured that, in the course of the operating behavior intended by the developers, an ID transmitter UWB signal transmitted by the ID transmitter 3 is received at both the first UWB antenna 7 and the second UWB antenna 7' with a signal strength sufficient for communication and signal evaluation. This ensures that, given a natural operating behavior of the operator 4, the specifications of the central UWB control unit 10 configured according to the invention can be implemented by the central UWB control unit 10.

[0072] In particular, the embodiment shown provides for communication between vehicle 2 and ID transmitter 3 to be discarded as non-authentic communication if a propagation time difference between a propagation time value of the UWB signal on route S1 and the UWB signal on route S2 is greater than a propagation time value corresponding to the distance between the first antenna 7 and the second antenna 7', S3. In this case, it can be concluded that at least one of the UWB signals has traveled a different route than route S1 or route S2, or that one of the signals may have been manipulated.

[0073] Thus, a communication system 1 of a vehicle 2 is shown in a preferred embodiment, wherein the preferred embodiment has four spaced-apart UWB antennas 7, 7', 7", 7‴, whose directions of maximum reception sensitivity are oriented perpendicular to one another and are selected to lie parallel to a driving plane of the vehicle 2. Two adjacent UWB antennas each form an overlap space, wherein the respective overlap space ensures that an ID transmitter 3 located near the vehicle can conduct UWB communication with the vehicle 2 via at least two of the UWB antennas of the vehicle 2. This ensures that improved security is achieved against compromise of the authentication of the ID transmitter 3.

[0074] For a specific design, the person skilled in the art can choose from many methods for implementing the communication system according to the invention. In particular, through targeted selection of antennas, targeted arrangement of the antennas on the vehicle, and optimized reception characteristics of the individual UWB antennas for desired applications, environmental areas referred to as overlap areas can be provided, within which an ID transmitter UWB signal is received by two or more UWB antennas.

[0075] To validate the received signal, various methods for checking the authenticity of the communication between the vehicle 2 and the ID transmitter 3 can be implemented, whereby, depending on the security requirements, the simultaneous fulfillment of several conditions can serve as a prerequisite for granting release of vehicle functions.

Claims

1. Communication system (1) of a vehicle (2) for the communication of the vehicle (2) with a portable ID transmitter (3), which is set up for UWB communication, for enabling vehicle functions for an operator (4) who carries the portable ID transmitter (3) with him, wherein the communication system (1) comprises at least a first UWB receiver (6) with a first UWB antenna (7) and a second UWB receiver (6') with a second UWB antenna (7'), wherein the first UWB antenna (7) and the second UWB antenna (7') are arranged at a distance from one another on the vehicle (2), wherein the direction of a maximum reception sensitivity of the first UWB antenna (7) and the direction of a maximum reception sensitivity of the second UWB antenna (7') are oriented at an angle to each other which is at least 30 degrees and / or the direction of a maximum reception sensitivity of the first UWB antenna (7) and the direction of a maximum reception sensitivity of the second UWB antenna (7') are oriented at an angle to each other which is at most 120 degrees, wherein a central UWB control unit (10) of the vehicle (2) is coupled to the first UWB receiver (6) and to the second UWB receiver (6'), wherein the central UWB control unit (10) is set up to evaluate both a first received signal of an ID transmitter UWB signal (12) received from the first UWB antenna (7) and a second received signal of the ID transmitter UWB signal (12) received from the second UWB antenna (7') as a function of one another for authentication of the communication of the vehicle (2) with the ID transmitter (3), wherein the UWB control unit (10) is set up to determine a first propagation time value of the first received signal and a second propagation time value of the second received signal, the communication between the ID transmitter (3) and the vehicle (2) being discarded as non-authentic communication, if a transit time difference of the first transit time value and the second transit time value exceeds a maximum transit time by more than a tolerated deviation, the maximum transit time being the time required to cover the distance between the first UWB antenna (7) and the second UWB antenna (7').

2. Communication system (1) according to claim 1, characterized in that an overlap space (15) exists in front of a driver's door (8) of the vehicle, within which space a reception sensitivity of the first UWB antenna (7) and a reception sensitivity of the second UWB antenna (7') exceed a minimum value at each location, wherein - an extension of the overlap space (15), - the selection, positioning and orientation of the UWB antennas (7, 7', 7'', 7‴), and - the selection of a UWB communication arrangement of the ID transmitter (3) are adapted to one another in such a way that UWB communication of the ID transmitter (3) with the vehicle can be carried out for the ID transmitter (3) both via the first UWB antenna (7) and via the second UWB antenna (7'), at least when the ID transmitter is positioned within the overlap space (15) .

3. Communication system (1) according to one of the preceding claims, characterized in that the UWB control unit (10) is set up to evaluate a first delay value of the first received signal and a second delay value of the second received signal by means of N-lateration.

4. Communication system (1) according to one of the preceding claims, characterized in that the UWB control unit (10) is set up, - to determine a transit time value for each of the detected received signals and to calculate an average transit time value from the determined transit time values, and / or - to determine a signal strength value for each of the detected received signals and to calculate an average signal strength value from the determined signal strength values, whereby a UWB distance value average value is derived from the transit time average value and / or the signal strength average value, wherein an LF distance value is determined from a signal strength of a detected LF signal of the ID transmitter, wherein the communication between the ID transmitter (3) and the vehicle (2) is discarded as non-authentic communication if the LF distance value and the UWB distance value average value deviate from each other beyond a tolerated maximum deviation.

5. Communication system (1) according to claim 4, characterized in that the tolerated maximum deviation is less than 30 percent, preferably less than 10 percent, of the calculated UWB distance mean value.

6. Communication system (1) according to one of the preceding claims, characterized in that the UWB control unit (10) is set up to reject the communication between ID transmitter (3) and the vehicle (2) as non-authentic communication if only exactly one of the UWB antennas registers a received signal of the ID transmitter UWB signal.

7. Communication system (1) according to one of the preceding claims, characterized in that the first UWB antenna (7) is arranged in a first handle on a driver's door (8) of the vehicle (2) and / or the second UWB antenna (7') is arranged in a second handle on a passenger door (9) of the vehicle (2).

8. Communication system (1) according to one of the preceding claims, characterized in that at least three, preferably at least four, spaced-apart UWB antennas (7, 7', 7", 7‴) are arranged on the vehicle (2).

9. Communication system according to claim 8, characterized in that four UWB antennas (7, 7', 7'', 7‴) spaced apart from one another are arranged on the vehicle (2), the directions of maximum reception sensitivity being oriented in each case perpendicular to one another and lying parallel to a driving plane of the vehicle.