Access control system for buildings

Abstract

Access control system (1) for buildings (2) with a stationary unit (20) and a mobile unit (10), wherein the mobile unit (10) has a mobile transceiver (11) which is designed to transmit wirelessly and encrypted signals (S) for authentication and authorization of the mobile unit (10) with respect to the stationary unit (20) and for control of the stationary unit (20) by the mobile unit (10) to a stationary transceiver (21) of the stationary unit (20), wherein the stationary unit (20) comprises a control device (22) which is designed to determine an actual position of the mobile unit (10) relative to the stationary unit (20) and a mirrored position of the mobile unit (10) from the signals (S) transmitted from the mobile transceiver (11) to the stationary transceiver (21), and wherein the stationary transceiver (21) is designed to transmit radar signals (RS) and to receive radar signals (RS) reflected back to the stationary transceiver (21), wherein the control device (22) is designed to determine a position of objects from radar signals (RS) transmitted by the stationary transceiver (21) and reflected back to the stationary transceiver (21), to compare the positions of the objects with the positions of the mobile unit (10), and to verify a matching position as the actual position of the mobile unit (10).

Description

[0001] The invention relates to an access control system for buildings.

[0002] An access control system within the meaning of the invention is understood to mean systems that have a stationary or fixed unit and a mobile unit that can be carried by a user, and in which said units communicate wirelessly with each other for the authentication and authorization of the mobile unit, and thus of the user, vis-à-vis the stationary unit. Based on the authentication and authorization, the stationary unit controls various functions and, in particular, the release or locking of an associated access, for example, a door or gate. Going beyond most conventional access systems, the access system according to the invention also provides for position determination, as explained in more detail below.

[0003] Wireless access control systems are state of the art and are known, for example, from the documents WO 2023 / 222462 A1 and DE 10 2020 114 403 A1.

[0004] However, such systems can be further optimized.

[0005] The invention is therefore based on the object of overcoming the aforementioned disadvantages and providing an access control system with improved security and increased convenience.

[0006] This problem is solved by the combination of features according to claim 1.

[0007] According to the invention, an access control system for buildings or a building access control system is therefore proposed, which accordingly has a stationary unit, i.e. a fixed unit and preferably a fixed unit connected to the building, and a mobile unit, i.e. a non-stationary unit and in particular a unit that can be carried by a user. The mobile unit is essentially an electronic key, which can be designed, for example, in the form of a smart FOB or a smartphone. Basically, both the stationary unit and the mobile unit have a respective transceiver, wherein a transceiver is to be understood as a transmitting / receiving unit. The transceiver of the mobile unit, referred to as the mobile transceiver, preferably has at least one antenna and an evaluation unit for transmitting signals via the at least one antenna and for evaluating the signals received via the at least one antenna.The transceiver of the stationary unit, referred to as the stationary transceiver, preferably has at least two antennas and an evaluation unit for transmitting signals via at least one of the two antennas and for evaluating the signals received via both antennas. The mobile transceiver is designed to transmit wirelessly, in particular via radio, and encrypted signals for authentication and authorization of the mobile unit to the stationary unit, as well as optionally for control of the stationary unit by the mobile unit, to the transceiver of the stationary unit, referred to as the stationary transceiver.

[0008] Fundamentally, it should be noted that authentication is understood as the verification of whether the mobile unit or its identity is known to the stationary unit, in particular, whether a unique identification number of the mobile unit is stored in the stationary unit. Authorization, on the other hand, is understood as the verification of whether the authenticated mobile unit has access authorization for the access controlled by the access control system. Authentication and authorization can be performed integrally or separately.

[0009] It is essential to the invention that the stationary unit has a control device which is designed to determine a position of the mobile unit relative to the stationary unit from the signals transmitted from the mobile transceiver to the stationary transceiver, wherein the position is determined in the form of two positions, of which the first position corresponds to an actual position of the mobile unit and the second position to a virtual or mirrored position of the mobile unit. Furthermore, it can be provided that the control device is designed to trigger or execute a function which corresponds in particular to a corresponding control command.to control if a control command to trigger the function is transmitted to the stationary unit by a mobile unit authenticated and authorized by the stationary unit and / or the actual position of the mobile unit is within a predetermined access area that can be learned in particular by a user or an authenticated and further preferably authorized user.

[0010] Due to the nature of position determination, it is usually not possible to determine a unique position. Instead, the actual position and a virtual or mirrored position are determined, which are initially indistinguishable for the stationary unit. Conventionally, the determined position, which would not trigger a function, can be excluded, thus compromising functionality and convenience at the expense of safety. However, to increase safety and convenience, it is advantageous if the position can be determined unambiguously, thus excluding the virtual or mirrored position and recognizing the actual position as the position of the mobile unit.

[0011] To solve this problem and accordingly essential to the invention, the stationary transceiver is designed to transmit radar signals and to receive radar signals reflected back to the stationary transceiver, wherein the control device is designed to determine a position of objects from radar signals transmitted by the stationary transceiver and reflected back to the stationary transceiver, to compare the positions of the objects with the positions of the mobile unit and to verify a position that matches, in particular, within a predetermined tolerance, as the actual position of the mobile unit.

[0012] Verification is understood to mean that the position of the previously determined possible positions, i.e. actual position and mirrored position, is confirmed as the position of the mobile unit, which corresponds to at least one position of an object.

[0013] The invention can therefore be summarized by proposing an access control system for buildings with a stationary unit and a mobile unit, each having a transceiver, wherein a control device of the stationary unit is designed to determine a position of the mobile unit relative to the stationary unit from the signals transmitted from the mobile transceiver to the stationary transceiver, to determine a position of objects from radar signals emitted by the stationary transceiver and reflected back to the stationary transceiver and to compare the positions of the objects with the position of the mobile unit and to verify the position of the mobile unit if there is a match.

[0014] The access area is understood to be a two-dimensional and horizontally extending area on or around the stationary unit and, accordingly, for example and in abstract terms, an area on a floor in the area of ​​the stationary unit or of an access controllable by the access control system, as could be represented, for example, in a view from above or a plan view.

[0015] The functions that can be controlled by corresponding control commands include, in particular, comfort functions, so that lighting elements, for example, can also be controlled by a corresponding control command.

[0016] However, basic functions of the access control system, and thus in particular unlocking and locking an access controlled by the access control system, preferably do not require the transmission of a control command, but are performed automatically by the control device when an authenticated and authorized mobile unit, i.e., its position, is within the access area. Repeated position determination also makes it possible to distinguish between entering and leaving the access area, and to trigger a corresponding function, e.g., unlocking the access upon entering and locking the access upon leaving.

[0017] The transceivers are preferably combined Bluetooth or Bluetooth Low Energy, BLE for short, and ultra-wideband transceivers, UWB transceivers for short, although other radio methods or radio transceivers can also be used, provided they enable the position to be determined according to the invention.

[0018] It is generally known that position determination is possible using such transceivers, but this will be explained in more detail below.

[0019] In radar operation or location mode, the stationary transceiver transmits radar signals that are reflected when they encounter an object, and in particular when they encounter the body of a person or user. These signals are then received by the stationary transceiver and evaluated by the transceiver or control device by correlating them with the transmitted radar signal with regard to distance, signal level, and direction of movement. The movement can be a breathing movement and / or a heartbeat movement of the person or user, as mentioned above, but also, for example, the movement of the user's extremities, for example, a movement of the user's legs that can be identified as a walking movement.

[0020] The advantage of using the radar signal is that the radar signal level when reflected off the user is not significantly influenced by the user's height or the location of the user's mobile transceiver on the body, e.g., in the front or back pocket. This, especially in conjunction with the large front-to-back ratio of the antennas, allows for reliable avoidance of ambiguities and verification of the position with a high degree of certainty.

[0021] To simplify position determination, it can be provided that the control device is designed to determine an angle from which the signals were received and a distance from which the signals were received from the signals transmitted from the mobile transceiver to the stationary transceiver, so that the position of the mobile unit can be specified as polar coordinates of a polar coordinate system lying in a horizontal plane, in whose coordinate origin the stationary transceiver is arranged.

[0022] Accordingly, the polar coordinate system preferably lies in a horizontal plane relative to the earth or the ground.

[0023] In the present case, however, an advantageous development provides that the access control system has, in particular, exactly one stationary transceiver, and the stationary transceiver has exactly two antennas for receiving the signals transmitted from the mobile transceiver to the stationary transceiver, wherein the exactly two antennas have a predetermined distance from each other in the horizontal plane. Based on this, the control device is configured to determine the angle from a phase shift between a signal received at both antennas and the distance between the antennas.

[0024] The phase shift can be determined using the so-called Phase Difference of Arrival (PDoA).

[0025] The angle is preferably determined using the formula Φ=arcsin(α∗λ2∗π∗d) with Φ is the angle from which the signal from the mobile transceiver was received by the stationary transceiver, α phase shift between the signal received at both antennas, λ as a wavelength of a carrier frequency of the signal and d is the distance between the two antennas in the horizontal plane.

[0026] With regard to the phase shift, it should be clarified that a signal is received by the two antennas spaced apart from each other with waves or phases shifted from each other due to the distance, whereby the phase shift corresponds to the shift of the phases or carrier waves from each other.

[0027] With regard to the wavelength of the carrier frequency of the signal, this can be determined by the control device from the signal, but can preferably already be stored in the control device or can be retrieved by it.

[0028] Likewise, the distance between the two antennas in the horizontal plane should preferably already be stored in the control device or be retrievable by it.

[0029] However, the calculation can apply to two angles or result in two angles, so that one of the angles is the actual angle of the actual position of the mobile unit and the other is merely a virtual or mirrored angle, which leads to the virtual or mirrored and thus not actual or incorrect position of the mobile unit.

[0030] Further advantageously, according to the invention, it can be provided that the control device is designed to determine a measured distance between the stationary transceiver and the mobile transceiver from a signal received at the stationary transceiver from the mobile transceiver.

[0031] The measured distance can be determined, for example, in that the control device is designed to determine the measured distance from a transmission time of a signal received at the stationary transceiver from the mobile transceiver (Time of Flight (ToF)) and / or from a transmission time of a signal received at the stationary transceiver from the stationary transceiver via the mobile transceiver and / or from a signal strength of a signal received at the stationary transceiver from the mobile transceiver (RSSI).

[0032] However, the measured distance corresponds to the length of the direct connection between the stationary and the mobile transceiver, so that a deviation may occur in the polar coordinate system extending in the horizontal plane due to a possible height difference between the mobile transceiver and the stationary transceiver in three-dimensional space.

[0033] An advantageous development of the invention, by means of which the transmission power can be increased and areas irrelevant for position determination can be excluded, provides that the stationary unit has a directional shield made of at least one electromagnetically reflecting layer, which is designed to limit a respective radiation angle of the antennas to a predetermined angular range.

[0034] In particular, it can be provided for this purpose that the stationary unit has a mounting side for fixing the stationary unit to the building, wherein the directional shield is arranged between the mounting side and the two antennas and thus, when used as intended, also between the antennas and the building, so that signals and radar signals sent by the antennas in the direction of the mounting side are shielded from the mounting side or the building and / or are reflected in an opposite direction, ie in a direction relevant for position determination or in an area on or in front of the building relevant for position determination.

[0035] Although not only UWB transceivers can transmit radio signals usable as radar signals, but also, for example, Wi-Fi radio and the radio technology known at the time of application as Bluetooth, or their transceivers, it should be briefly explained with regard to UWB that the radiation from the antennas is restricted by the directional shield in such a way that the radiation on the rear side of an antenna reference plane passing through the antennas, which, during intended use, faces the building, is reduced. For this purpose, the directional shield can be attached to the side of a housing of the stationary transceiver or its antennas that faces the building during intended use and can be formed from at least one electromagnetically reflective layer.The directional shield not only reduces the radiation towards the mounting side, thus essentially limiting the radiation angle of the antennas to half, but at the same time increases the radiation on the front side of the stationary transceiver facing away from the mounting side, so that the antennas essentially correspond to a directional antenna.

[0036] As is well known, the front-to-back ratio (F / B) is an important metric for antennas. It indicates how well an antenna radiates in the desired direction (front) compared to the opposite direction (back or mounting side). It describes the ratio of the radiated power in the main beam direction (front) to the radiated power in the opposite direction (back) of the antenna, or in this case, of both antennas.

[0037] The front-to-back ratio for UWB antennas in radar operation in the 6 to 8.5 GHz range is approximately 30 to 40 dB. This means that if the user is located at the rear of the stationary transceiver, and in particular inside a building, the UWB radar signal level received at the stationary transceiver is up to 40 dB lower than if the user is located at the front of the stationary transceiver or in front of the building. This reduced UWB radar signal level is used, taking into account a suitable decision threshold, to decide whether the user is at the front or rear of the stationary transceiver, i.e. in front of the building or inside the building. If the UWB radar signal level is below the suitable decision threshold, the user or the object in general will be detected as being in front of the building.whose position is behind the mounting side of the stationary transceiver and thus inside the building.

[0038] Accordingly, it is preferably provided that the control device is designed to determine a signal level from radar signals transmitted by the stationary transceiver and reflected back to the stationary transceiver and to determine from a comparison of the signal level with a previously known decision threshold value, which is in particular stored in the control device or can be called up by the latter, whether the positions of the mobile unit are in an area in front of the stationary transceiver or in front of a directional screen of the stationary unit, ie outside the building, or in an area behind the stationary transceiver or the directional screen of the stationary unit, ie inside the building.

[0039] This information can be used, on the one hand, to verify the position and, on the other hand, to control functions. For example, access should only be unlocked when the user approaches the building and is therefore in front of it. Conversely, it can be specified that access should remain locked when the user is inside the building to prevent any other unauthorized person from gaining access.

[0040] In general, but particularly when using UWB signals or UWB transceivers, due to the high accuracy in radar operation or location mode, it can be provided that the control device is designed to determine a movement of the objects from radar signals emitted by the stationary transceiver and reflected back to the stationary transceiver and to compare the movement of the objects with at least one predetermined movement pattern, which is in particular a breathing movement pattern and / or a heartbeat movement pattern of a person or a walking movement pattern, so that it can be determined by the comparison whether the object is a person.

[0041] For example, the movement of a person's chest can be detected as an object and the direction of movement of the object can be determined on the one hand and whether it is a person or an inanimate object, such as a car, on the other hand.

[0042] Furthermore, by evaluating the movement pattern of the legs or by comparing the movement with a walking movement pattern generated by a person's legs, it can also be determined whether the person is a human.

[0043] Furthermore, with regard to breathing movement, while it is possible to reliably distinguish between inanimate and animate objects, an animal may exhibit a similar breathing movement pattern to a human. However, by combining a comparison of a recorded movement with a breathing movement pattern and a walking movement pattern, it is usually possible to reliably distinguish between humans and animals.

[0044] As explained in the introduction, this information can be used to verify the position of the mobile transceiver or mobile unit.

[0045] However, it can further be provided that the control device is designed to compare the positions of the objects with the position of the mobile unit and to verify the position of the mobile unit only if the position of the mobile unit matches an object identified as a human, wherein, based on this, it can be provided that the control device is designed to control or trigger the function only if the position of the mobile unit corresponds to the position of the object identified as a human.

[0046] By storing or retrievable corresponding patterns in or through the control device, it is also possible to distinguish between adult users and children as users, whereby instead of a person, animals, for example, can also be recognized by means of correspondingly stored patterns.

[0047] When comparing the positions determined for the mobile transceiver or mobile unit and the objects determined by the radar signals or their positions, it is also important that they can match within a predetermined tolerance in order to be considered to match.

[0048] Although it has already been stated that preferably the stationary transceiver or precisely one stationary transceiver is designed to send and receive both the signals for communication and the radar signals, according to an advantageous development and to simplify this functional combination, the stationary transceiver is designed to send signals to the mobile transceiver in a communication mode and to receive signals from the mobile transceiver and to send radar signals and receive reflected radar signals in a locating mode, wherein the stationary transceiver can be operated alternately in the communication mode and the locating mode.

[0049] Furthermore, it can be provided that the stationary transceiver, for example controlled by the control device, can be operated repeatedly in the communication mode at time intervals determined by a first time interval and / or can be operated in the locating mode at time intervals determined by a second time interval.

[0050] According to a further aspect of the invention, an access control system according to the invention, and in particular the control device, is designed to carry out a method for verifying a position of a mobile unit of an access control system for buildings according to the invention. The method provides that a position of the mobile unit relative to the stationary unit is determined from the signals transmitted from the mobile transceiver to the stationary transceiver, a position of objects is determined from radar signals emitted by the stationary transceiver and reflected back to the stationary transceiver, and the positions of the objects are compared with the position of the mobile unit, in particular taking into account a predetermined tolerance. If the position or possible positions of the mobile transceiver match one of the positions of the objects, the position of the mobile transceiver is or will be verified.

[0051] Furthermore, it can be provided that the function is only triggered or activated when the verified position of the mobile unit is within a predetermined access area. Optionally, this may also require that a mobile unit authenticated and authorized by the stationary unit transmit a control command to the stationary unit to trigger the function.

[0052] What has been said about the access control system also applies directly and analogously to the method proposed according to the invention.

[0053] The features disclosed above can be combined as desired, as long as this is technically possible and they do not contradict each other.

[0054] Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. They show: Fig. 1 an access control system in a plan view; Fig. 2 a segmentation of a polar coordinate system determined by distance grids and angle grids; Fig. 3 Section of an access control system in a top view; Fig. 4 Section of an access control system in a side view; Fig. 5 alternating operation of a stationary transceiver; Fig. 6 schematic structure of a stationary unit; Fig. 7 a procedure for verifying a position of a mobile unit.

[0055] The figures are schematic examples. Like reference numerals in the figures indicate like functional and / or structural features.

[0056] In Fig. 1, the essential components of an access control system 1 on a building 2 according to the invention are shown schematically.

[0057] Such an access control system 1 basically comprises a stationary unit 20 and a mobile unit 10, wherein the stationary unit 20 is stationary or connected to the building 2 and is designed to control the access 3, for example a door, of the building 2 and accordingly, in particular, to lock or unlock the access 3 or the door 3 depending on the position of the mobile unit 10, wherein the stationary unit 20 receives signals S from the mobile unit 10 to determine the position and to authenticate and authorize the mobile unit 10. The mobile unit 10 has a mobile BLE-UWB transceiver 11, which is designed to wirelessly and encryptedly transmit signals S for authentication and authorization of the mobile unit 10 to the stationary unit 20 and, if necessary, for control of the stationary unit 20 by the mobile unit 10 to a stationary BLE-UWB transceiver 21 of the stationary unit 20.

[0058] In general, identification and authentication preferably take place via BLE, whereas localization and positioning preferably takes place via cryptologically secured communication via UWB.

[0059] It can be provided that the control of the stationary unit 20 should not be based, or preferably at least not exclusively, on control commands received from the mobile unit 10, but rather it should be checked whether the mobile unit is located within a predetermined access area 30.

[0060] Accordingly, the stationary unit 20 has a control device 22, which is designed to determine a position of the mobile unit 10 relative to the stationary unit 20 from the signals S transmitted from the mobile transceiver 11 to the stationary transceiver 21 and to automatically control a function when the position of the mobile unit 10 is within a predetermined access area 30. Optionally, it may also be necessary for a control command to trigger the function to be transmitted to the stationary unit 20 by a mobile unit 10 authenticated and authorized by the stationary unit 20.

[0061] As exemplified in the Fig. 1 and Fig. 2, the predetermined access area can be a delimited area or a delimited region within a polar coordinate system, in the center of which the stationary unit 20 is arranged. However, the predetermined access area 30 can be a predetermined angular range, distance range, a combination of angular and distance range, or the entire area of ​​the stationary unit that can be detected by the polar coordinate system, so that in the latter case, the access area 30 would be determined solely by a maximum transmission or reception power of the two transceivers 11, 21 or the transmission or reception power of the stationary transceiver 21 operating in location mode or radar mode.

[0062] Basically, it is provided that the control device 22 determines an angle Φ from which the signals S were received from the signals S transmitted from the mobile transceiver 11 to the stationary transceiver 21, and determines a distance r from which the signals S were received, so that the respective position of the mobile unit 10 can be specified as polar coordinates of the polar coordinate system.

[0063] As particularly with reference to Fig. 4, the polar coordinate system is understood as extending in a horizontal plane 5, which accordingly runs essentially parallel to the ground 6 or to a surface 6 of a reference system that can be designated as ground 6.

[0064] In order to simplify and thus accelerate calculations and comparisons, it can be provided that the polar coordinate system is divided by a distance grid 41 and an angle grid 42 or is segmented into individual segments 46, so that virtual, i.e. imaginary, nodes 43 are formed at the intersection points of the distance grid 41 with the angle grid 42, whereby each segment 46 is determined by four nodes 43, as shown in Fig. 2 is shown.

[0065] Based on this, the control device 22 can be configured to normalize the previously determined position of the mobile unit 10 to the nearest node 43.

[0066] Also with reference to Fig. 2 shows that the access area 30 can be determined, for example, by boundary points 31 normalized to the node points 43.

[0067] The determination of the angle Φ is schematic and simplified in Fig. 3, where only the mobile transceiver 11 and the stationary transceiver 21 are shown in the Fig. 1 and Fig. 2 referenced view from above.

[0068] The stationary transceiver 21 accordingly has exactly two antennas 23 for receiving a signal S transmitted from the mobile transceiver 11 to the stationary transceiver 21, wherein the exactly two antennas 23 have a known distance d from each other in the horizontal plane.

[0069] The angle Φ is determined from a phase shift α between the signal S received at both antennas 23 or a phase shift α between the carrier waves 24 of the signal S received at both antennas 23 and the distance d between the antennas 23.

[0070] In particular, the angle Φ is given by the formula Φ=arcsin(α∗λ2∗π∗d) determined, where λ is known in advance as a wavelength of the carrier frequency or the carrier wave 24 of the signal S and is in particular stored in the control device 22 or can be retrieved by it.

[0071] The formula mentioned is, as in Fig. 3, but valid for two angles Φ or for two coordinates, so that in addition to the actual position of the mobile unit 10 or its mobile transceiver 11, a mirrored or virtual position of an image of the mobile transceiver 11 that is not actually present and can therefore be designated as a “ghost transceiver” 12 is also determined.

[0072] For the stationary transceiver 21 or the control device 22, it cannot be clearly determined from these two possible positions at which of the positions the mobile transceiver 11 or the mobile unit 10 is actually located.

[0073] Therefore, in addition to the position determination from the signals transmitted from the mobile unit 10 to the stationary unit 20, an additional location or position determination using radar signals RS is provided, as shown schematically in Fig. 4. It should be noted that the radar signals RS transmitted by the stationary unit 20 or its stationary transceiver 21 do not specifically determine the position of the mobile unit 10, but rather all positions of all detectable objects.

[0074] Due to the high accuracy of a UWB transceiver 21 operating in radar or positioning mode, even the smallest movements of objects can be detected and evaluated by transmitting radar signals RS and evaluating the reflected radar signals RS received again by the stationary UWB transceiver 21.

[0075] In particular, the breathing movement and / or heartbeat movement of a person can be detected based on the movement of the chest 7 and / or the movement of the skin of a person or user 4, and the object can therefore be recognized as a human. A control command can also be derived from a movement and, in particular, a movement pattern.

[0076] If the object identified as a human or user remains for three seconds, for example, the control device 22 generates a control command to unlock the access.

[0077] Alternatively, however, it is also possible for a walking movement of a person to be detected based on the movement of the extremities or legs of a person or user 4 and for the object to be identified as a human being.

[0078] If a position of the mobile unit 10 determined from the signals S then agrees within a predetermined tolerance with a position of an object determined from the radar signals RS, this position is the actual position of the mobile unit, which is verified as such.

[0079] Since, in the case of objects, it is also possible to distinguish between inanimate and animate objects, i.e. persons or users 4, by evaluating their movement, the verification of the position can only take place if the position of the mobile unit 10 determined from the signals S corresponds within a predetermined tolerance to a position of an object identified as a person or human being determined from the radar signals RS, which object is therefore the user 4 carrying the mobile unit 10.

[0080] In order to be cost and space efficient, the stationary transceiver 21 can be operated in two different and alternating modes, as shown in Fig. 5 schematically shown. The stationary transceiver 21 is controlled, for example, by the control device 22, operated recurrently at time intervals determined by a first time interval T1 in the communication mode, in which the signals S are received and evaluated, and operated at time intervals determined by a second time interval T2 in the locating mode, in which the radar signals RS are transmitted, received, and evaluated.

[0081] To further improve the location or position determination and verification of the position, a stationary unit 20, as shown in Fig. 6, a directional screen 25 may also be provided, which is formed from at least one electromagnetically reflecting layer.

[0082] The directional screen 25 shields the signals S emitted by the antennas 23 as well as the radar signals RS from the building 2 and thus from the side not relevant for the evaluation.

[0083] For this purpose, the directional shield 25 is arranged between the antennas 23 and a mounting side 27 of the mobile unit 20 which, when used as intended, faces the building 2 and is in this case flat.

[0084] Although the directional shield 25, as shown, can preferably be arranged as part of the stationary transceiver 21 and in particular directly on the antennas 23, it is sufficient for the function if the directional shield is arranged between the antennas 23 and the mounting side 27 and thus at the alternative positions 26 shown as examples.

[0085] An exemplary procedure for verifying the position of the mobile unit 10 is shown in Fig. 7, wherein the control device 22 can be designed accordingly to carry out a method based thereon or at least some of the steps.

[0086] According to the Fig. The procedure shown in Figure 7 and based on a flow chart includes, in particular, the following steps: Step A The stationary unit 20 determines a position of the mobile unit 10 relative to the stationary unit 20 from the signals S transmitted from the mobile transceiver 11 to the stationary transceiver 21. Step B The stationary unit 20 and in particular the control device 22 checks whether the position of the mobile unit 10 is within a radar range of the stationary unit 20 or the stationary transceiver 21. Step C Is the position of mobile unit 10 within radar range? If yes, proceed to step D. If no, return to step A. Step D The stationary transceiver 21 is switched to radar operation, ie the location mode. Step E The stationary transceiver 21 transmits radar signals RS. Step F The stationary transceiver 21 receives the reflected radar signals RS and uses them to determine a position of the user 4. Step G The position of the mobile unit 10 is compared with the position of the user 4. Step H Do the positions match? If no, go to step J. If yes, go to step K. Step J The positions do not match, so the mobile unit 10 is not carried by a user 4 and no functions are to be controlled. Step K: The positions match, so the mobile unit 10 is being carried by a user 4. The position of the mobile unit 10 is thus verified. The corresponding signal level, i.e., the corresponding radar signal level, is also determined from the associated radar signal. Step L The stationary unit 20 and in particular the control device 22 checks whether the radar signal level of the radar signal RS is greater than a decision threshold at which the user 4 is outside the building 2, or is less than the decision threshold so that the user 4 is inside the building 2. Step M Is the radar signal level greater than the decision threshold? If no, go to step N. If yes, go to step O. Step N The mobile unit 10 is detected as being located in the building 2. Step O The mobile unit 10 is detected as being in front of building 2. Step P The stationary transceiver 21 is switched to normal operation, ie the communication mode. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2023 / 222462 A1

[0003] DE 10 2020 114 403 A1

[0003]

Claims

[1] Access control system (1) for buildings (2) with a stationary unit (20) and a mobile unit (10), wherein the mobile unit (10) has a mobile transceiver (11) which is designed to transmit wirelessly and encrypted signals (S) for authentication and authorization of the mobile unit (10) with respect to the stationary unit (20) and for control of the stationary unit (20) by the mobile unit (10) to a stationary transceiver (21) of the stationary unit (20), wherein the stationary unit (20) comprises a control device (22) which is designed to determine an actual position of the mobile unit (10) relative to the stationary unit (20) and a mirrored position of the mobile unit (10) from the signals (S) transmitted from the mobile transceiver (11) to the stationary transceiver (21), and wherein the stationary transceiver (21) is designed to transmit radar signals (RS) and to receive radar signals (RS) reflected back to the stationary transceiver (21), wherein the control device (22) is designed to determine a position of objects from radar signals (RS) transmitted by the stationary transceiver (21) and reflected back to the stationary transceiver (21), to compare the positions of the objects with the positions of the mobile unit (10), and to verify a matching position as the actual position of the mobile unit (10). [2] Access control system according to claim 1, wherein the control device (22) is designed to determine from the signals (S) transmitted from the mobile transceiver (11) to the stationary transceiver (21) an angle (Φ) from which the signals (S) were received, and to determine a distance (r) from which the signals (S) were received, so that the position of the mobile unit (10) can be specified as polar coordinates of a polar coordinate system in whose coordinate origin the stationary transceiver (21) is arranged. [3] Access control system according to claim 2, wherein the stationary transceiver (21) has exactly two antennas (23) for receiving the signals (S) transmitted from the mobile transceiver (11) to the stationary transceiver (21), wherein the exactly two antennas (23) have a known distance (d) from each other in the horizontal plane, and wherein the control device (22) is designed to determine the angle (Φ) from a phase shift (α) between a signal (S) received at both antennas (23) and the distance (d) between the antennas (23). [4] Access control system according to the preceding claim, wherein the stationary unit (20) has a directional screen (25) made of at least one electromagnetically reflective layer, which is designed to limit a respective radiation angle of the antennas (23) to a predetermined angular range. [5] Access control system according to the preceding claim, wherein the stationary unit (20) has a mounting side (27) for fixing the stationary unit (20) to the building (2), wherein the directional shield (25) is arranged between the mounting side (27) and the two antennas (23), so that signals (S) and radar signals (RS) transmitted by the antennas (23) in the direction of the mounting side (27) are shielded from the mounting side (27) and / or reflected in an opposite direction. [6] Access control system according to one of the preceding claims, wherein the control device (22) is designed to determine a movement of the objects from radar signals (RS) emitted by the stationary transceiver (21) and reflected back to the stationary transceiver (21), and to compare the movement of the objects with a predetermined movement pattern, which is in particular a breathing movement pattern and / or a heartbeat movement pattern of a person. [7] Access control system according to the preceding claim, wherein the control device (22) is designed to compare the positions of the objects with the position of the mobile unit (10) and to verify the position of the mobile unit (10) exclusively if the position of the mobile unit (10) matches an object (41) identified as a human, and / or wherein the control device (22) is designed to control the function only when the position of the mobile unit (10) corresponds to the position of the object (41) identified as a human. [8] Access control system according to one of the preceding claims, wherein the stationary transceiver (21) is designed to transmit signals (S) to the mobile transceiver (11) in a communication mode and to receive signals (S) from the mobile transceiver (11) and to transmit radar signals (RS) and to receive reflected radar signals (RS) in a locating mode, wherein the stationary transceiver (21) is operable alternately in the communication mode and the locating mode and / or is operable recurrently in the communication mode at time intervals determined by a first time interval (T1) and / or is operable in the locating mode at time intervals determined by a second time interval (T2). [9] Access control system according to one of the preceding claims, wherein the control device (22) is designed to determine a signal level from radar signals (RS) emitted by the stationary transceiver (21) and reflected back to the stationary transceiver (21) and to determine from a comparison of the signal level with a previously known decision threshold whether the positions of the mobile unit (10) are in an area in front of the stationary transceiver (21) or in an area behind the stationary transceiver (21).

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