Determining the position of a communication device in relation to a motor vehicle

Abstract

The invention relates to a method for determining the position of a radio-based communication device (20) in relation to a motor vehicle (10) having several radio antennas (12, 14, 16, 18, 20), wherein first radio signals are transmitted by means of the radio antennas, which the communication device receives, received field strengths for the first radio signals are recorded, received field strength data are determined and transmitted to the motor vehicle by means of a second radio signal, wherein the position of the communication device (22) takes into account predetermined antenna-specific field strength distribution data, wherein the field strength distribution data specify a field strength distribution for each radio antenna in relation to an ambient area (24) of the motor vehicle.The invention provides that, depending on the antenna-specific field strength distribution data in the area surrounding the motor vehicle, at least horizontally adjacent segment areas (26, 28, 30, 32) are determined, and for each segment area at least one of the radio antennas is determined which is more sensitive for this segment area than at least one other of the radio antennas, wherein the position of the communication device is determined depending on an assignment of the received field strength data to the respective segment areas.

Description

[0001] The invention relates to a method for determining the position of a radio-based communication device in relation to a motor vehicle having several radio antennas, by means of which the radio antennas transmit first radio signals, wherein the communication device receives at least two of the first radio signals, detects the received field strengths of the received first radio signals, determines the received field strength data for the detected received field strengths, and transmits the received field strength data to the motor vehicle by means of a second radio signal, wherein the position of the communication device is determined on the motor vehicle side based on the transmitted received field strength data in relation to the motor vehicle, wherein predetermined antenna-specific field strength distribution data are taken into account to determine the position.wherein the field strength distribution data specify at least a horizontal field strength distribution for each radio antenna with respect to a predetermined area surrounding the motor vehicle. The invention further relates to a device for determining the position of a radio-based communication device with respect to a motor vehicle having multiple radio antennas, wherein the device is arranged on the motor vehicle, wherein the device is configured to transmit first radio signals by means of the radio antennas, wherein the device is configured to receive a second radio signal from the communication device, which the communication device transmits to the motor vehicle in response to receiving at least two first radio signals, wherein the communication device detects received field strengths for the received first radio signals, determines received field strength data for the detected received field strengths and transmits them to the motor vehicle by means of the second radio signal.The device is configured to determine the position of the communication device on the vehicle side based on the transmitted received field strength data in relation to the vehicle, the device taking into account predetermined antenna-specific field strength distribution data for determining the position, the field strength distribution data specifying at least a horizontal field strength distribution for each radio antenna in relation to a predetermined area surrounding the vehicle. The invention further relates to a vehicle with multiple radio antennas and a device communicating with the radio antennas, at least for access authorization or for the intended operation of the vehicle. Finally, the invention also relates to a computer program product and a computer-readable medium.

[0002] Generic methods, devices, and motor vehicles, as well as computer program products and computer-readable media, are known in the prior art. For example, DE 10 2015 226 661 A1 discloses a method for wireless communication between a mobile identification transmitter (as a communication device) and a vehicle (as a motor vehicle). Several radio antennas are arranged at different positions on the vehicle. These antennas transmit initial radio signals at regular intervals; these signals may, for example, be initialization signals. These initial radio signals may contain, among other things, data for identifying the respective antenna transmitting the initial radio signal. Furthermore, the initial radio signals may also contain additional data as needed, such as data relating to the identification of the motor vehicle or the like.

[0003] The first radio signals can be received, at least partially, by the communication device as soon as the device is within communication range of the vehicle. The communication device can be, for example, a smartphone, a key fob, or another type of identification transmitter. The communication device receives at least two initial radio signals and records the respective signal strengths for each of them. Since the vehicle's radio antennas are located in different positions, there is usually a difference in signal strengths between them. Because the initial radio signals contain identification data relating to the antenna transmitting each signal, the communication device can assign the recorded signal strengths to the respective antennas of the vehicle.Thus, it is possible to determine received field strength data for the recorded signal strengths, preferably also including identification data of the respective radio antenna that transmitted the first radio signal. The communication device transmits the received field strength data for, preferably all, received first radio signals to the vehicle by means of a second radio signal.

[0004] The vehicle receives the second radio signal from the communication device via at least one of its radio antennas or an additional receiving antenna provided for this purpose, so that the vehicle can determine the position of the communication device relative to the vehicle based on the transmitted signal strength data. This makes it possible, among other things, not only to determine whether a user of the communication device has access to the vehicle or authorization to use it as intended, but also whether the user is in a position relative to the vehicle that suggests an imminent or intended use of the vehicle.

[0005] To determine the position, vehicle-specific antenna-specific field strength distribution data is taken into account, wherein the field strength distribution data specifies at least a horizontal field strength distribution for each radio antenna with respect to a given area surrounding the vehicle. The field strength distribution data can, for example, comprise a field strength map at least two-dimensionally for a horizontal plane, but preferably also three-dimensionally, for a spatial area surrounding the vehicle. DE 10 2021 002 010 A1 discloses a method that describes a procedure by which a field strength map with respect to the vehicle can be determined.

[0006] Environmental factors, such as the electrical conductivity of the ground, magnetic properties of the ground or objects, humidity, or similar conditions, can cause the field strength values ​​shown on the field strength map to deviate from the actual field strength values ​​in the vicinity of the vehicle. This can result in a significant discrepancy between the communication device's position relative to the vehicle, as determined in this way, and its actual position.

[0007] The invention is based on the objective of improving the accuracy in determining the position of the communication device relative to the motor vehicle.

[0008] The invention proposes a method, a device, a motor vehicle, a computer program product and a computer-readable medium according to the independent claims as a solution.

[0009] Advantageous further training opportunities arise from the characteristics of the dependent requirements.

[0010] With regard to a generic method, the invention particularly proposes that, depending on the antenna-specific field strength distribution data in the area surrounding the motor vehicle, at least horizontally adjacent segment areas are determined, and for each segment area at least one of the radio antennas is determined which is more sensitive for this segment area than at least one other of the radio antennas, wherein the position of the communication device is determined at least depending on an assignment of the received field strength data to the respective segment areas.

[0011] With regard to a generic device, the invention particularly proposes that the device is configured to determine at least horizontally adjacent segment areas depending on the antenna-specific field strength distribution data in the ambient area around the motor vehicle, and to determine for each segment area at least one of the radio antennas that is more sensitive for this segment area than at least one other of the radio antennas, wherein the device is configured to determine the position of the communication device at least depending on an assignment of the received field strength data to the respective segment areas.

[0012] With regard to a motor vehicle of the type described, the invention specifically proposes that the device be designed according to the invention.

[0013] With regard to a generic computer program product, the invention particularly proposes that the computer program product includes instructions that cause a program-controlled computer unit of a device of the invention arranged on a motor vehicle with several radio antennas to transmit first radio signals by means of the radio antennas in order to determine a position of a radio-based communication device in relation to the motor vehicle, to receive a second radio signal from the communication device, which the communication device transmits to the motor vehicle in response to receiving at least two of the first radio signals, wherein the communication device detects the received field strengths of the received first radio signals, determines received field strength data for the detected received field strengths and transmits them to the motor vehicle by means of the second radio signal.and to determine the position of the communication device on the vehicle side based on the transmitted received field strength data in relation to the vehicle, taking into account specified antenna-specific field strength distribution data for determining the position, wherein the field strength distribution data specify at least a horizontal field strength distribution for each radio antenna in relation to a specified ambient area of ​​the vehicle, to determine at least horizontally adjacent segment areas in the ambient area around the vehicle depending on the antenna-specific field strength distribution data, to determine at least one of the radio antennas for each segment area that is more sensitive for this segment area than at least one other of the radio antennas, and to determine the position of the communication device at least depending on an assignment of the received field strength data to the respective segment areas,when the instructions are executed by the computer unit.

[0014] With regard to a generic computer-readable medium, the invention particularly proposes that the computer program product according to the invention is stored on the computer-readable medium in a way that can be read by a computer unit.

[0015] The invention is based, among other things, on the idea that determining the position of the communication device relative to the vehicle can be improved by dividing the field strength map into areas that can be specifically optimized for evaluation. This can be achieved through segmentation, whereby at least one radio antenna is selected for each segment that is particularly sensitive to that segment. Depending on the segment, several radio antennas can also be selected that are particularly sensitive to that segment. The area around the vehicle is thus segmented, that is, divided into segments, at least horizontally. However, it is also possible to define spatial segments that also take a vertical range into account. In this case, segments can also be arranged vertically, at least partially, one above the other.

[0016] Preferably, the segment areas collectively surround the motor vehicle substantially completely, such that the surrounding area can be substantially completely encompassed by the segment areas. The surrounding area or the segment areas preferably border partially on an outer skin of the motor vehicle. It is also possible that one or more segment areas do not border on the outer skin.

[0017] The segment areas, or surrounding area, extend over a predetermined distance from the vehicle's outer skin, which can preferably be constant around the vehicle. However, this distance can also vary around the vehicle, for example, depending on the characteristics of the radio antennas, the vehicle's construction, and / or the like. The surrounding area covers at least a substantially horizontal plane. Preferably, however, the surrounding area covers a spatial area that also includes a predetermined height. The predetermined height can, for example, be defined by a solid angle, and in particular, it can be a height at which a user can generally be expected to position the communication device. In this way, it is possible to determine, based on the received field strength data, the antenna for which the highest received field strength has been recorded.Preferably, additional radio antennas can also be considered for which a second-highest or third-highest received field strength has been recorded. This allows the radio antenna closest to the communication device to be determined, so that the corresponding segment area can be identified as the area in which the communication device is located. Within this segment area, the radio antenna is more sensitive than at least one of the other radio antennas. The position of the communication device relative to the vehicle can thus be determined, at least as a function of the assignment of the received field strength data to the respective segment areas.

[0018] The invention is not limited to a single radio antenna determining a given segment area. It can also be provided that a given segment area is determined by two or more radio antennas. Preferably, however, not all received field strength data from all radio antennas are considered for determining the respective segment area. This makes it possible to disregard received field strength data from those radio antennas for which only a small, and in particular a very small, received field strength was recorded. It should be borne in mind that, especially at low received field strengths, deviations due to environmental characteristics, particularly soil properties, can be particularly large.In the prior art, considering these received data sets has the disadvantage of potentially increasing deviations in determining the position of the communication device relative to its actual position. The method according to the invention significantly reduces this deviation, especially since it takes into account that such deviations or influences can be considerably reduced at high received field strengths. Overall, the invention thus enables not only a simplified method but also a more accurate and reliable determination of the communication device's position relative to the vehicle.

[0019] For the purposes of this invention, the terms "radio" and "radio technology" refer in particular to a method of wirelessly transmitting signals of all kinds using modulated waves in the radio frequency range or radio waves. In particular, wireless propagation of waves may be provided, for example, due to an electromagnetic field, a magnetic field, an electric field, and / or the like.

[0020] According to a further development approach, it is proposed that for at least one of the segment areas, at least two radio antennas be selected that are more sensitive to that segment area than at least one other radio antenna. In this way, segment areas can be created that are not solely determined by the high sensitivity of a single radio antenna. For example, it is possible to define an additional segment area between two segment areas, each defined by a single radio antenna and its sensitivity, that is determined by the high sensitivity of the two radio antennas for which the immediately adjacent segment areas have the highest sensitivity. This makes it possible to achieve fine segmentation even with a small number of radio antennas.

[0021] It is further proposed that, for each segment area, the antenna-specific field strength distribution data be sorted at least with respect to a segment-specific sensitivity of the radio antennas. The sorting can involve sorting the radio antennas for the respective segment area according to their sensitivity. This allows for improved signal processing, particularly with regard to determining the position of the communication device.

[0022] Furthermore, it is proposed that the radio antennas be weighted according to their segment-specific sensitivity for a given segment area. This can further improve or simplify the determination of the communication device's position, as a radio antenna with high sensitivity for a particular segment area would receive a large weighting factor. This would further enhance the reliability and accuracy of the communication device's position determination.

[0023] It is further proposed that, for determining the position of the communication device, the received field strength data from at least two radio antennas for which the communication device has recorded the highest received field strengths should be considered. This will further improve the position determination because essentially only the received field strength data for which particularly high received field strengths were recorded need to be taken into account. Received field strength data for which only low values ​​were recorded can thus be disregarded for position determination, especially since this received field strength data is particularly sensitive to interference or influences from environmental factors. The accuracy and reliability of the position determination of the communication device can thereby be further improved.

[0024] Furthermore, it is proposed that, for determining the position of the communication device, received field strength data from at least one of the radio antennas for which the communication device has detected the lowest received field strength is disregarded. This also further improves the invention, because the lowest detected received field strength is generally unable to contribute significantly to the position determination.

[0025] According to a further training, it is proposed that adjacent segment areas should overlap at least partially. This has the advantage of improving the evaluation regarding the assignment of received signal strength data to the respective segment areas, especially when the communication device is located in a border area between two adjacent segment areas. In this way, hysteresis can be created in the evaluation, thus enabling reliable functionality.

[0026] Furthermore, it is proposed that for at least one segment area, a predetermined portion of a number of radio antennas be considered, with the determination of the communication device's position depending on the assignment of the received field strength data to this segment area. This also improves the evaluation with regard to assigning the received field strength data to the respective segment areas, because signal processing only needs to be performed with respect to the predetermined number of radio antennas. In particular, received field strength data for radio antennas that are not required for the intended functionality of the invention for the respective segment area do not need to be considered. This also further improves reliability and accuracy.

[0027] Furthermore, it is proposed that only received field strength data exceeding a predefined reference value be considered for the assignment. This reference value determines that the communication device is within a specified communication range of the vehicle, particularly its radio antennas. Communication devices outside this defined distance are disregarded. This further improves reliability and reduces signal processing requirements. The reference value is preferably chosen such that the distance is approximately 5 meters, particularly approximately 3 meters or even less.

[0028] Furthermore, it is proposed that, preferably taking into account the received field strength data, the antenna-specific field strength distribution data be at least partially updated. This updating can be performed, for example, due to known environmental influences such as an open vehicle door, an open hatch, or the like, particularly on motor vehicles. If a known change in field strength occurs in a specific segment due to a known environmental influence in that segment, the field strength distribution data of one or more radio antennas can be adjusted for evaluation in that segment according to the known environmental influence. Furthermore, the received field strength data can be used to determine deviations in the field strength distribution data that may arise, for example, due to environmental influences.The field strength distribution data can then be updated accordingly, further improving the functionality of the invention. Depending on requirements, the update can be repeated, for example, if a deviation exceeds a predefined deviation comparison value, or in response to specific events, at regular intervals, a combination thereof, and / or the like.

[0029] Furthermore, a further development proposal suggests using different radio bands for transmitting the first and second radio signals. This approach has the advantage that the resulting communication channels can be separated by a frequency difference. Moreover, this design allows the first radio signals to be transmitted at a relatively low frequency, for example, in the range of approximately 100 kHz to 450 kHz. In contrast, the second radio signal can be transmitted in a significantly higher frequency range, for example, in the range of approximately 300 MHz to 900 MHz. This can also lead to advantages in terms of energy consumption and design.

[0030] To at least partially carry out the described steps, a processor circuit or computer unit can be provided that includes a program or software, or a computer program product, comprising program instructions which, upon execution of the program instructions, cause the processor circuit to perform an embodiment of the method. The processor circuit can include at least one microprocessor and / or microcontroller for this purpose. The program instructions can be stored in a data memory of the processor circuit.

[0031] The invention also includes further developments of the device according to the invention, which have features already described in connection with the further developments of the method according to the invention. For this reason, the corresponding further developments of the device according to the invention are not described again here.

[0032] 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.

[0033] The invention also includes combinations of the features of the described embodiments.

[0034] An embodiment of the invention is described below. The following is shown: Fig. 1 a schematic top view of a motor vehicle with a device for determining the position of a radio key relative to the motor vehicle; Fig. 2 a schematic representation of how Fig. 1 with a radio key arranged in the vicinity of the motor vehicle, wherein several radio antennas are arranged on the motor vehicle; Fig. 3 a schematic representation of how Fig. 1, where the surrounding area is segmented; and Fig. 4. A schematic flowchart for determining the position of the radio key relative to the motor vehicle.

[0035] The embodiment described below is a preferred embodiment of the invention. In this embodiment, 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 embodiment can also be supplemented by other features of the invention already described.

[0036] In the figures, functionally identical elements are each provided with the same reference symbols.

[0037] Fig. Figure 1 shows a schematic top view of a motor vehicle 10 with several radio antennas 12, 14, 16, 18, 20 ( Fig. 2) and with a device 34 in communication connection with the radio antennas 12, 14, 16, 18, 20, which in this case serves for access authorization and for the intended operation of the motor vehicle 10. A surrounding area 24 is formed around the motor vehicle 10, which provides a communication area for radio-based communication with a radio key 22 ( Fig. 2) determined. In this embodiment, the surrounding area 24 is divided into a first sub-area 36 and a second sub-area 38. Sub-areas 36 and 38 are arranged concentrically to each other and surround the motor vehicle 10. Sub-area 36 is enclosed by sub-area 38. In the present embodiment, sub-area 36 extends to a distance of approximately 2 m from the outer skin of the motor vehicle 10. Sub-area 38 extends from an outer circumference of sub-area 36 to a distance of approximately 4 m to approximately 5 m from the outer skin of the motor vehicle. Communication between the radio key 22 and the motor vehicle 10 is possible within the surrounding area 24.

[0038] Fig. Figure 2 shows in a schematic representation how Fig. 1 the radio key 22 arranged in the area 24 surrounding the motor vehicle 10. From Fig. Figure 2 further shows where the radio antennas 12, 14, 16, 18, 20 are located on the motor vehicle 10. The radio antennas are in communication contact with the device 34. From Fig. 2 It is further evident that the surrounding area 24 is affected by external influences compared to the representation according to Fig. 1 may have changed.

[0039] For the ambient area 24, the device 34 has access to antenna-specific field strength distribution data, wherein the field strength distribution data in the present embodiment is a spatial field strength distribution for each of the radio antennas 12, 14, 16, 18, 20 with respect to the specified ambient area 24 of the motor vehicle 10 according to Fig. 1. For each of the radio antennas 12, 14, 16, 18, 20, a corresponding spatial field strength distribution is thus specified with respect to the surrounding area. This creates a field strength map.

[0040] During normal operation, initial radio signals are transmitted by means of radio antennas 12, 14, 16, 18, and 20. These initial radio signals may be initialization signals containing at least identification data relating to the respective transmitting radio antenna 12, 14, 16, 18, or 20, as well as the vehicle 10. The initial radio signals are transmitted sequentially in a predetermined order with a time delay. The transmission of the initial radio signals is controlled by device 34.

[0041] The radio key 22 receives the first radio signals when it is within communication range, that is, within the ambient area 24. The radio key 22 records the respective received field strengths for each of the first radio signals received. The radio key 22 also determines received field strength data for each recorded received field strength, which in this case includes the corresponding identification data of the respective radio antennas 12, 14, 16, 18, 20 and the vehicle 10. The received field strength data is transmitted from the radio key 22 to the vehicle 10 by means of a second radio signal.

[0042] The device 34 is designed to determine the position of the radio key 22 on the vehicle side based on the transmitted received field strength data in relation to the vehicle 10. For this purpose, the device 34 takes into account the specified antenna-specific field strength distribution data. Since possible positions can be determined for each of the radio antennas 12, 14, 16, 18, 20 based on the respective detected received field strengths, the position of the radio key 22 can be determined simply without complex signal processing.

[0043] For this purpose, the device 34 is designed to determine adjacent segment areas 26, 28, 30, 32 in the ambient area 24 around the motor vehicle 10, depending on the antenna-specific field strength distribution data. This is to be done using Fig. Figure 3 shows this procedure for a rear right area of ​​the motor vehicle 10. This procedure can be continued accordingly for the other areas.

[0044] For each segment area 26, 28, 30, 32, at least one of the radio antennas 12, 14, 16, 18, 20 is selected which is more sensitive for this segment area 26, 28, 30, 32 than at least one other radio antenna 12, 14, 16, 18, 20. The device 34 is configured to determine the position of the radio key 22 depending on an assignment of the received field strength data to the respective segment areas 26, 28, 30, 32.

[0045] Out of Fig. Figure 3 shows that, in the present configuration, for segment 30, radio antenna 16 provides the strongest, radio antenna 20 the second strongest, and radio antenna 14 the third strongest received field strength. For segment 28, radio antenna 16 provides the strongest, radio antenna 20 the second strongest, and radio antenna 18 the third strongest received field strength. Similarly, in segment 26, radio antenna 16 provides the strongest and radio antenna 18 the second strongest received field strength. In segment 32, radio antenna 18 provides the strongest and radio antenna 16 the second strongest received field strength. Therefore, it is possible to determine the position of the radio key 22 almost immediately and with minimal computational effort based on the received field strength data transmitted by the radio key 20.

[0046] At the same time, this method allows for the elimination of the need to consider all received field strength data for position determination, as explained above. For example, received field strength data relating to radio antenna 12 are not required for segment areas 26, 28, 30, and 32. Therefore, if the radio key 22 is positioned in one of the aforementioned segment areas 26, 28, 30, or 32, received field strength data from radio antenna 12 do not need to be considered. Moreover, it is to be expected that the received field strength data relating to radio antenna 12 will provide the lowest value in these cases anyway.Especially when the received field strength can be influenced by external environmental factors, it proves advantageous for the accuracy of the position determination to disregard small received field strengths for position determination, because these can usually have large effects due to external influences.

[0047] Fig. Figure 4 shows a schematic flowchart for determining the position of the radio key 22 relative to the motor vehicle 10. In step 40, the device 34 causes the radio antennas 12, 14, 16, 18, 20 to transmit their respective first radio signals. This allows a transmission cycle to be determined. In the present embodiment, the transmission is repeated after approximately 0.5 s.

[0048] In step 42, the radio key 22 receives the first radio signals of the current transmission cycle and records the respective received field strengths for each signal. In step 44, the radio key 22 determines the respective received field strength data for the recorded received field strengths, taking into account the respective identification data of the radio antennas 12, 14, 16, 18, and 20. In step 46, the radio key 22 transmits the received field strength data to the vehicle 10 via a second radio signal, which can be received by one or more of the radio antennas 12, 14, 16, 18, and 20. In an alternative embodiment, a separate radio antenna can also be provided as a receiving antenna for the second radio signal.

[0049] In step 48, the device 34 determines the position of the communication device 22, as explained previously.

[0050] Overall, this example demonstrates how determining the position of a communication device in relation to a motor vehicle can be provided. Reference symbol list 10 motor vehicle 12 radio antenna 14 radio antenna 16 radio antenna 18 radio antenna 20 radio antenna 22 remote keys 24 surrounding area 26 Segment area 28 Segment area 30 segment area 32 Segment area 34 Device 36 Sub-area 38 Sub-area 40 steps Step 42 Step 44 Step 46 48 steps QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 10 2015 226 661 A1

[0002] DE 10 2021 002 010 A1

[0005]

Claims

[1] Method for determining the position of a radio-based communication device (20) in relation to a motor vehicle (10) having several radio antennas (12, 14, 16, 18, 20), wherein first radio signals are transmitted by means of the radio antennas (12, 14, 16, 18, 20), wherein the communication device (22) receives at least two of the first radio signals, records the received field strengths of the received first radio signals, determines the received field strength data for the recorded received field strengths and transmits the received field strength data to the motor vehicle (10) by means of a second radio signal, wherein the position of the communication device (22) is determined on the motor vehicle side based on the transmitted received field strength data in relation to the motor vehicle (10), wherein specified antenna-specific field strength distribution data are taken into account to determine the position,wherein the field strength distribution data specify at least a horizontal field strength distribution for each radio antenna (12, 14, 16, 18, 20) with respect to a given ambient area (24) of the motor vehicle (10), , characterized by , that depending on the antenna-specific field strength distribution data in the ambient area (24) around the motor vehicle (10), at least horizontally adjacent segment areas (26, 28, 30, 32) are determined, and for each segment area (26, 28, 30, 32) at least one of the radio antennas (12, 14, 16, 18, 20) is determined which is more sensitive for this segment area (26, 28, 30, 32) than at least one other of the radio antennas (26, 28, 30, 32), wherein the position of the communication device (22) is determined at least depending on an assignment of the received field strength data to the respective segment areas (26, 28, 30, 32). [2] Method according to claim 1, wherein for at least one of the segment areas (26, 28, 30, 32) at least two of the radio antennas (12, 14, 16, 18, 20) are selected which are more sensitive for this segment area (26, 28, 30, 32) than at least one further of the radio antennas (12, 14, 16, 18, 20). [3] Method according to one of the preceding claims, wherein for each segment area (26, 28, 30, 32) the antenna-specific field strength distribution data are sorted at least with respect to a segment-specific sensitivity of the radio antennas (12, 14, 16, 18, 20). [4] Method according to claim 3, wherein the radio antennas (12, 14, 16, 18, 20) are weighted depending on their segment-specific sensitivity for a respective segment area (26, 28, 30, 32). [5] Method according to one of the preceding claims, wherein for determining the position of the communication device (22) those received field strength data of at least two radio antennas are taken into account for which the communication device (22) has detected the greatest received field strengths. [6] Method according to one of the preceding claims, wherein for determining the position of the communication device (22) received field strength data from at least one of the radio antennas (12, 14, 16, 18, 20) is disregarded for which the communication device (22) preferably detected the smallest received field strength. [7] Method according to any of the preceding claims, wherein adjacent segment regions (26, 28, 30, 32) overlap at least partially. [8] Method according to one of the preceding claims, wherein for at least one segment area (26, 28, 30, 32) a predetermined part of a number of radio antennas (12, 14, 16, 18, 20) is taken into account, wherein the determination of the position of the communication device (22) is dependent on the assignment of the received field strength data to this segment area (26, 28, 30, 32). [9] Method according to one of the preceding claims, wherein for the assignment only the received field strength data are taken into account where the detected received field strengths are greater than a predetermined reference value. [10] Method according to one of the preceding claims, wherein preferably taking into account the received field strength data, the antenna-specific field strength distribution data are at least partially updated. [11] Method according to one of the preceding claims, wherein different radio bands are used for transmitting the first and second radio signals. [12] Device (34) for determining the position of a radio-based communication device (22) in relation to a motor vehicle (10) having several radio antennas (12, 14, 16, 18, 20), wherein the device (34) can be arranged on the motor vehicle (10) and connected to the radio antennas (12, 14, 16, 18, 20), wherein the device (34) is configured to transmit first radio signals by means of the radio antennas (12, 14, 16, 18, 20), wherein the device (34) is configured to receive a second radio signal from the communication device (22), which the communication device (22) transmits to the motor vehicle (10) in response to receiving at least two of the first radio signals, wherein the communication device (22) detects received field strengths for the received first radio signals, and transmits received field strength data for the detected Received field strengths are determined and transmitted to the motor vehicle (10) by means of the second radio signal, wherein the device (34) is designedto determine the position of the communication device (22) on the motor vehicle side based on the transmitted received field strength data in relation to the motor vehicle (10), wherein the device (34) for determining the position takes into account predetermined antenna-specific field strength distribution data, wherein the field strength distribution data specify at least a horizontal field strength distribution for each radio antenna (12, 14, 16, 18, 20) in relation to a predetermined ambient area (24) of the motor vehicle (10), thereby, characterized in that the device (34) is configured to determine, depending on the antenna-specific field strength distribution data in the ambient area (24) around the motor vehicle (10), at least horizontally adjacent segment areas (26, 28, 30, 32), and for each segment area (26, 28, 30, 32) to determine at least one of the radio antennas (12, 14, 16, 18, 20) which is more sensitive for this segment area (26, 28, 30, 32) than at least one other of the radio antennas (12, 14, 16, 18, 20), wherein the device (34) is configured to determine the position of the communication device (22) at least depending on an assignment of the received field strength data to the respective segment areas (26, 28, 30, 32). [13] Motor vehicle (10) with several radio antennas (12, 14, 16, 18, 20) and with a device (34) in communication connection with the radio antennas (12, 14, 16, 18, 20) at least for the purpose of granting access or for the intended operation of the motor vehicle (10), characterized by , that the device (34) is designed according to claim 12. [14] Computer program product with instructions that cause a program-controlled computer unit of a device (34) arranged on a motor vehicle (10) with several radio antennas (12, 14, 16, 18, 20) according to claim 11 to transmit first radio signals by means of the radio antennas (12, 14, 16, 18, 20) in order to determine a position of a radio-based communication device (22) in relation to the motor vehicle (10), to receive a second radio signal from the communication device (22), which the communication device (22) transmits to the motor vehicle (10) in response to receiving at least two of the first radio signals, wherein the communication device (22) detects received field strengths for the received first radio signals, determines received field strength data for the detected received field strengths and transmits them to the motor vehicle (10) by means of the second radio signal,and to determine the position of the communication device (22) on the vehicle side based on the transmitted received field strength data in relation to the vehicle (10), taking into account specified antenna-specific field strength distribution data for determining the position, wherein the field strength distribution data specify at least a horizontal field strength distribution for each radio antenna (12, 14, 16, 18, 20) in relation to a specified ambient area (24) of the vehicle (10), depending on the antenna-specific field strength distribution data in the ambient area (24) around the vehicle (10), to determine at least horizontally adjacent segment areas (26, 28, 30, 32), and to determine for each segment area (26, 28, 30, 32) at least one of the radio antennas (12, 14, 16, 18, 20) that is more sensitive than at least one for this segment area (26, 28, 30, 32). further radio antennas (12, 14, 16, 18, 20) is,and to determine the position of the communication device (22) at least depending on an assignment of the received field strength data to the respective segment areas (26, 28, 30, 32) when the instructions are executed by the computer unit. [15] Computer-readable medium on which the computer program product according to claim 14 is stored in a readable manner by a computer unit.

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