Method for transmitting an emergency message from a transmitting vehicle to at least one receiving vehicle over a radio network and motor vehicle, transmitting circuit and receiving circuit

Abstract

The invention relates to a method for transmitting an emergency message (25) from a transmitting vehicle (29) to at least one receiving vehicle (33) via a radio network (17), while in the radio channel (27) of the radio network (17) a normal message (31) has already been emitted by a radio network participant (30) different from the transmitting vehicle (29), wherein in the method the transmitting circuit (20) of the transmitting vehicle (29) emits the emergency message (25) in the transmission channel at a transmission level (39) which is lower than the transmission level (40) of the normal message (31), the corresponding receiving circuit (22) of the at least one receiving vehicle receives from the radio channel (27) a superimposed signal (38) which contains the normal message (31) and the emergency message (25), extracts the normal message (31) from the superimposed signal (38), determines a residual signal (45) which describes the difference between the superimposed signal (38) and the extracted normal message (43), and reconstructs the emergency message (25) from the residual signal (45).

Description

TECHNICAL FIELD

[0001] The invention relates to a method for transmitting a message from a sending vehicle to at least one receiving vehicle via a radio network. The message is to be transmitted with as short a time delay as possible, since the message is to be regarded as an emergency message. The invention also relates to a sending circuit for issuing such an emergency message and a receiving circuit for receiving an emergency message. Finally, the invention also comprises a motor vehicle in which such a sending circuit and / or receiving circuit is provided. BACKGROUND

[0002] A plurality of motor vehicles exchange messages via a radio network, which can coordinate their driving maneuvers in an automated driving operation or by means of a driver assistance function. Thus, the motor vehicles can, for example, carry out a platooning operation or a platooning drive, in which synchronized joint driving maneuvers, such as simultaneous acceleration or braking, are carried out. The synchronization of the driving maneuvers and the form of the maneuvers can be achieved in the radio network by means of radio-based messages.

[0003] A radio standard for the presetting of such messages in the radio network can be, for example, the so-called V2V communication (V2V - Vehicle to vehicle, vehicle to vehicle) or V2X communication (V2X - Vehicle to anything, vehicle to any other communication object or radio network participant). As messages, simple messages without a directional connection can be provided, which are issued according to the "fire and forget" principle, according to which no waiting or expectation of an acknowledgment of the possible receipt by the receiving vehicle is necessary. Conversely, complex interactions can be provided, which correspond to a communication with a directional connection and for each communication sequence or exchange process at least three messages, for example three V2X messages, are provided, wherein the content of the second and third messages and each further message is respectively related to the content of at least one previous message, which can originate from a different motor vehicle and / or other V2X participant (for example a sending boat (Sendebarke) at the roadside). Such complex interactions are defined, for example, by the 5GAA (5G Automotive Association). Here, a platform or framework is developed on the so-called application layer, which specifies a protocol for the complex interaction. The 5GAA does not, however, deal with the protocols for the underlying communication layer (PHY, MAC, PDCP), but rather new technical solutions are considered, for example the 5G NR V2X standard (3GPP R16, 3GPP R17) for such a communication layer. Thus, both unicast and multicast transmission and the reliable delivery of data packets can be considered, for example by means of a hybrid automatic repeat request (HARQ) as a transmission scheme.

[0004] A basic problem in the communication on the application layer or Application-Layer is that the complex interaction of motor vehicles with one another by means of a plurality of messages always assumes that all motor vehicles of a vehicle platoon or all motor vehicles in a radio network jointly receive a message relating to a next driving maneuver and respond accordingly. That is, a prerequisite for this application case is that the motor vehicles are synchronized in the planning of a driving maneuver and also jointly execute the driving maneuver, which the motor vehicles uniformly decide upon in one decision step, for example brake simultaneously.

[0005] However, it can occur that a driving situation arises in which a motor vehicle must interrupt the platooning, i.e. for example can no longer participate in the radio network. The above can occur when an unexpected event occurs, for example an obstacle on the roadway, or a medical emergency occurs, for example when a vehicle occupant is unwell. The motor vehicle must then leave the group of motor vehicles driving in platooning, i.e. end the coordinated operation with the other motor vehicles. This motor vehicle can then either join another group of vehicles driving in coordination, which is currently more relevant to the motor vehicle, or plan an individual action for the motor vehicle itself independently. However, the last task of the motor vehicle in the coordinated driving operation until then is to inform the current group of vehicles to which it belongs that the coordinated driving operation ends, so that the remaining motor vehicles in the group of vehicles can take into account the uncoordinated driving operation of the exiting motor vehicle.

[0006] However, since the interruption of the coordinated driving operation usually occurs in an emergency, there is a high communication requirement at the time of the interruption, i.e. the radio channel of the radio network can be occupied by another participant of the radio network, since the remaining motor vehicles also need to communicate with one another, so that the emergency message of the motor vehicle wanting to report to the remaining motor vehicles that the coordinated driving operation ends can be delayed.

[0007] Motor vehicles exchanging messages with one another by means of a radio network are described, for example, in DE 10 2015 104 553 A1. The transmission of messages takes place on the basis of a data transmission synchronized in preset time slots. If a participant of the radio network issues a message during a time slot, the transmission operation of the remaining participants of the radio network must be blocked. As a result, the remaining participants cannot issue an emergency message.

[0008] A description of V2X communication is known from DE 10 2013 226 605 A1. Here, the issued messages are referred to as announcements.

[0009] From EP 3 585 078 A1 it is set forth in connection with V2X communication that by means of V2X communication not only a coordinated driving operation for autonomous motor vehicles can be realized, but also a coordinated driving operation can be realized by means of a driver assistance device of a motor vehicle in general.

[0010] The publication by Watanabe et al. (WATANABE, Y., SATO, K., FUJII, T.; Title: A scheduling method for V2V networks using successive interference cancellation, 2016 IEEE Vehicular Networking Conference (VNC), IEEE, 2016. S. 1-2. - ISSN 2157-9865) sets forth that by means of a variant of SIC (successive interference cancellation) it can be determined in an AdHoc radio network of motor vehicles which motor vehicles simultaneously transmit in a synchronization phase according to the ALOHA criterion. Depending on the distance between the motor vehicles, the signals of a plurality of motor vehicles have different signal strengths in the receiving motor vehicles, which serves to allow two motor vehicles to transmit in the same time slot, since the signals of these motor vehicles can be separated again in all receiving vehicles by means of SIC.

[0011] In US 2011 / 0034 201 A1 it is set forth that a car-to-car communication can take place on the basis of data packets and for this purpose a header of the data packet can be defined.

[0012] In US 2020 / 0064 140 A1 it is set forth that motor vehicles drive in a platoon and for this purpose an AdHoc radio network can be formed for a coordinated driving maneuver. Vehicles can join or leave the network. SUMMARY

[0013] It is the object of the present application to transmit an emergency message from a transmitting vehicle to at least one receiving vehicle with little delay by means of a radio network used by the motor vehicles among each other.

[0014] The object is achieved by the subject matter of the independent claims. Advantageous embodiments of the application are set forth in the dependent claims, the following description and the drawings.

[0015] The first aspect of the application relates to a method for transmitting an emergency message from a transmitting vehicle to at least one receiving vehicle via a radio network, while in the radio channel of the radio network a normal message has already been issued by a radio network participant different from the transmitting vehicle, wherein in the method the transmitting circuit of the transmitting vehicle issues the emergency message in the radio channel at a transmission level which is lower than the transmission level set for transmitting the normal message in the radio channel. Thus, it is assumed by the method that at the time when the emergency message should be issued, the radio channel can already be occupied. The message or announcement being transmitted here is referred to as normal message. Normal message means that the further participant of the radio channel regularly issues its normal message because the radio channel was free for the further participant or the further participant itself was the first to occupy the radio channel for issuing the normal message. The normal message is in particular issued according to a radio standard, that is to say that the signal level and / or the coding is adapted or determined by the further participant according to the radio standard. Now, if in the transmitting vehicle the transmitting circuit of the transmitting vehicle detects that the radio channel is already occupied, but nevertheless does not intercept the emergency message, but rather superimposes or superposes the emergency message with the normal message by issuing the emergency message as a superimposed signal at a transmission level which is lower than the transmission level set for transmitting the normal message according to the radio standard, in the same radio channel in which the normal message is transmitted. In other words, the signal level of the emergency message is lower than the signal level of the normal message. The term "radio channel" refers in a known manner to a frequency band in which the messages are transmitted in the radio network. Thus, the normal message and the emergency message occupy the same radio channel or the same frequency band in the frequency spectrum. That is to say, the normal message and the emergency message form a superimposed signal or a superposed signal.

[0016] For the respective receiving vehicle, the method provides that the respective receiving circuit of the at least one receiving vehicle receives from the radio channel a superimposed signal which contains the normal message and the emergency message, reconstructs the normal message from the superimposed signal, models the signal component of the normal message from the reconstructed normal message, determines a residual signal which describes the difference between the superimposed signal and the modelled signal component of the normal message from the superimposed signal and the modelled signal component of the normal message, and reconstructs the emergency message from the residual signal. The superimposed signal is thus the signal which is received by the receiving circuit from the radio channel, i.e. from the environment, via the antenna. Since the emergency message has been emitted with a lower transmission level, the normal message is the strongest signal or the dominant signal, and the receiving circuit can reconstruct this normal message in a known manner, for example by correlation reception and / or decoding. The normal message has a transmission level which is set for the radio channel which is free according to the radio standard of the radio network. If the normal message is then present in a separate manner, an unnatural (abnormal) transmission signal can be produced therefrom, as would be possible when the normal message should be emitted again. The residual signal results from the difference between the received superimposed signal and the modelled signal component of the normal message which the superimposed signal necessarily has. Since the dominant signal of the normal message is now removed or at least reduced in the residual signal, the emergency message can also be reconstructed again by known methods for signal reception, i.e. for example by correlation reception and / or decoding. Reconstruction means that the digital data of the respective message (normal message and emergency message) is extracted or detected from the signal process. In order to determine the residual signal, the superimposed signal can be temporarily stored until the modelled signal component is formed. The superimposed signal can be the received signal in the frequency bank of the radio channel or in the intermediate frequency or in the base band.

[0017] An advantage achieved by the application is that, when the emergency message should be emitted, no time delay occurs even if the radio channel is occupied. It is thus not necessary to wait until the radio channel is free again.

[0018] In the application, a modem which drives the transmission circuit is used in order to adjust the transmission level. In addition or alternatively, an antenna compensation circuit is switched off. In order to adjust the transmission level for the emergency message purposefully, the modem which drives the transmission circuit can thus be used. In addition or alternatively, the antenna compensation circuit which automatically matches the transmission level for the normal message can also be switched off when the emergency message is transmitted, with particularly low technical complexity. Thereby, the mentioned jump or the mentioned reduction of the transmission level by 6 to 10 decibels is achieved.

[0019] The application also comprises embodiments which achieve additional advantages.

[0020] In one embodiment, in the respective receiving vehicle, for the signal component of the normal message which is modeled by the message data of the reconstructed normal message, the transmission signal of the participant who sent the normal message is copied and the copied transmission signal is matched to the reception level which the superimposed signal has at the reception circuit in order to determine the signal component. In other words, the unnatural transmission signal is produced from the message data of the reconstructed normal message, i.e. the reception process is carried out in reverse or in the opposite direction, in order to obtain the signal course of the transmission signal over time and / or its spectrogram. In addition, it is considered that each receiving vehicle monitors a further reception level of the normal message, since the respective receiving vehicle is at a different distance from the participant who sent the normal message, whereby the attenuation of the transmission signal of the participant is also different. Therefore, the reception level of the superimposed signal is used to scale or so to speak attenuate the copied transmission signal, so that the amplitude of the copied transmission signal and the amplitude of the superimposed signal meet a consistency criterion. For example, the consistency criterion can stipulate that the maximum value of the superimposed signal and the maximum value of the copied transmission signal must coincide and / or the envelope of the superimposed signal and the envelope of the copied transmission signal match in terms of amplitude. The synchronization in time can be set, for example, by means of a correlation, so that the copied transmission signal is first synchronized in time with the superimposed signal.

[0021] In one embodiment, in a radio network normal messages are transmitted in predetermined time slots of synchronous data transmission. The transmitting circuit of a sending vehicle then emits its emergency message with a predetermined time offset relative to the start time of the time slot, and the receiving circuit, in order to check whether an emergency message is contained in the superimposed signal, checks the signal portion in the superimposed signal which corresponds to the start time of the time slot plus the predetermined time offset for the presence of a predetermined header (header data) of a possible emergency message. Preferably, the time offset is zero in order not to lose time. That is to say, synchronous data transmission takes place in the time slot. The transmitting circuit transmits the emergency message in the time slot in which the normal message is also transmitted. In particular, the time offset can be zero, i.e. the transmitting circuit transmits its emergency message at the same time as another participant emits its normal message. The emergency message is thus also completely in the time slot. By knowing in the receiving circuit with what time offset the transmitting circuit inserts the emergency message into the time slot, i.e. for example at the same time as the time slot begins (time offset 0), it can be purposefully checked by detecting the header, for example by means of correlation, whether a possible emergency message is contained in the time slot at all. At this point, the header of the emergency message can be known in the receiving circuit, for example stored in a memory and / or in a correlation circuit. The emergency message is preferably a message whose content is already known in the receiving circuit (so-called well-known message). Thus, it is not the content of the emergency message itself for passing on information which is involved, but rather the fact that the emergency message has indeed been emitted by the sending vehicle, which can represent information to the respective receiving vehicle. In addition to synchronous data transmission, packet-oriented data transmission can also be provided.

[0022] In one embodiment, in a radio network a plurality of modulation and coding schemes and / or numerology concepts are provided for transmitting normal messages, and from these the coding with the greatest redundancy and / or rateless coding scheme is used for the emergency message. Thus, the radio standard of the radio network (modulation and coding scheme, NR - Numerology Concept) can provide that the coding rate or the redundancy component in the respective transmitted signal of the normal message can be matched to the noise level in such a way that the coding rate is selected from a plurality of possible, predetermined coding rates. This is the so-called modulation and coding scheme and / or numerology concept. Here, for the emergency message the coding with the smallest coding rate is selected, or, conversely, the coding with the greatest redundancy is selected. It is thereby ensured that the emergency message can be reliably reconstructed and / or recognized by the respective receiving circuit, despite the greater signal transmission level or signal level of the normal message.

[0023] In one embodiment, the transmission level of the emergency message is adjusted to be lower than the transmission level of the normal message by a multiple of 6 to 10 decibels. In order to achieve, on the one hand, an error-free reconstruction of the normal message (the emergency message represents additional noise for the normal message) and, on the other hand, a reliable reconstruction of the emergency message itself, said value interval for the transmission level of the emergency message has proven to be particularly effective. The transmission level can be adjusted adaptively depending on the noise level adapted by the transmission circuit and / or the reception level of the normal message.

[0024] In one embodiment, the transmitting vehicle and the at least one receiving vehicle use a radio network as an AdHoc network for a coordinated driving operation, and the emergency message is reported, the transmitting vehicle interrupts the coordinated driving operation and / or leaves the AdHoc network. In the described manner, the transmission of the emergency message is important, in particular in an AdHoc network for a coordinated driving operation of motor vehicles, for example platooning. The emergency message can then be a message with which the transmitting vehicle reports to each receiving vehicle that the transmitting vehicle interrupts the coordinated driving operation and / or even leaves the AdHoc network.

[0025] According to one aspect, the invention relates to a transmitting circuit for a motor vehicle, wherein the transmitting circuit has a control device which is set to transmit a message characteristic of an emergency into a radio channel of a radio network and, in doing so, to detect whether the radio channel is occupied by a normal message transmission of another participant and, in this case, to emit the message as an emergency message in the radio channel at a transmission level which is lower than a transmission level set for transmitting normal messages in accordance with a radio standard of the radio channel. The method steps relating to the transmitting vehicle can thus be carried out by means of the transmitting circuit. The transmitting circuit can also be improved in the described manner by implementing additional features as already set out in connection with the embodiments of the method according to the invention in the transmitting circuit as well.

[0026] According to one aspect, the invention relates to a receiving circuit for a motor vehicle, wherein the receiving circuit is set to receive a superimposed signal containing normal messages and emergency messages from a radio channel of a radio network and to reconstruct the normal messages from the superimposed signal, to model a signal component of the normal messages in the superimposed signal from the reconstructed normal messages, to determine a residual signal describing a difference between the superimposed signal and the modelled signal component of the normal messages from the superimposed signal and the modelled signal component of the normal messages, and to reconstruct the emergency messages from the residual signal. The receiving circuit can thus carry out the method steps of the embodiments of the method according to the invention provided for the respective receiving vehicle.

[0027] The transmitting circuit and / or the receiving circuit can each have a control circuit here to carry out and / or trigger or control the method steps described. The control circuit can have a data processing device or processor device which is set up to carry out an embodiment of the method according to the application. To this end, the processor device can have at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (field-programmable gate array) and / or at least one DSP (digital signal processor). Furthermore, the processor device can have program code which, when implemented by the processor device, carries out an embodiment of the method according to the application. The program code can be stored in a data memory of the processor device.

[0028] According to one aspect, the application relates to a motor vehicle having an embodiment of a transmitting circuit according to the application and / or having an embodiment of a receiving circuit according to the application. The motor vehicle according to the application is preferably designed as a car, in particular as a passenger car or a heavy goods vehicle, or as a bus or a motorcycle. That is to say, the motor vehicle according to the application can be operated as a transmitting vehicle for a coordinated driving operation and / or (in another driving situation) as a receiving vehicle.

[0029] The application also comprises combinations of features of the embodiments described. That is to say, the application also comprises embodiments which each have a combination of features of a plurality of the embodiments described, provided that these embodiments are not described as being mutually exclusive. BRIEF DESCRIPTION OF DRAWINGS

[0030] Embodiments of the application are explained below. Among others:

[0031] Figure 1 A schematic diagram of an embodiment of a motor vehicle according to the application is shown; and

[0032] Figure 2 A flowchart for illustrating an embodiment of a method according to the application is shown. DETAILED DESCRIPTION

[0033] The embodiments explained below are preferred embodiments of the application. The individual parts of the embodiments described in the embodiments each represent separate features of the application which are to be considered as independent of one another and which each improve the application independently of one another. The disclosure should therefore also include combinations different from the features of the embodiments shown. Furthermore, the embodiments described can also be supplemented by other features of the application already described.

[0034] The same reference signs in the figures each represent functionally identical elements.

[0035] Figure 1A motor vehicle 10 is shown, which can be driven on a road 11. An example situation is shown, in which the motor vehicle 10 first waits at a traffic light 12 and a phase change 13, by which the traffic light 12 jumps to green, allows the motor vehicle 10 to start. In the motor vehicle 10, a driver assistance function 14 can be provided, which can be designed as an autonomous driving function or as a function to assist the driver, for example ACC (automatic cruise control). By means of the driver assistance function 14, the motor vehicle 10 can, for example, be driven in coordination as a platoon 15 or, in general, a coordinated driving operation 16 by means of the driver assistance function 14. A possible example for another coordinated driving operation 16 is a crossroad, at which the motor vehicle 10 automatically takes note of the right of way. In the coordinated driving operation 16 as a platoon 15, it can be provided, for example, that the motor vehicles 10 jointly start or accelerate after the phase change 13, so that these motor vehicles start moving in a serpentine manner or in the manner of a platoon.

[0036] For the coordinated driving operation 16, the motor vehicles 10 can be coupled or coordinated with one another by means of a radio network 17 for coordinated driving maneuvers. For example, acceleration values for starting can be coordinated between the motor vehicles 10. To this end, each motor vehicle 10 can have a communication circuit 18, which can operate the radio network 17, for example, on the basis of WIFI or mobile radio. The radio channel 27 can be based on a V2X communication standard, among others. The radio network 17 can be an AdHoc network, for example, to which the motor vehicles 10 can participate, which are located within a common transmission range, i.e., can be reached directly by means of a radio connection (without the aid of a mobile radio network or another static network). The respective communication circuit 18 can be coupled with the driver assistance function 14 by means of a control circuit 19, which can be designed as a transmission circuit 20 for sending messages 21 and / or as a receiving circuit 22 for receiving messages 21.

[0037] A prerequisite for the coordinated driving operation 16 is that each of the participating motor vehicles 10 also respectively actually knows and is able to perform the agreed driving maneuvers. In Figure 1 In the example situation shown in Fig. 1, an unexpected traffic obstacle 24 makes it impossible for one of the motor vehicles 10, here referred to as motor vehicle 23, to perform the coordinated driving operation. As a traffic obstacle 24, for example, a pedestrian or cyclist can be in the driving path of the motor vehicle 23. In order for the remaining motor vehicles 10 to take note of the fact that the motor vehicle 23, despite the agreed driving maneuver, does not perform this driving maneuver and / or other coordinated driving maneuvers, the motor vehicle 23 must inform the remaining motor vehicles 10 by means of an emergency message 25 that the motor vehicle 23 interrupts the coordinated driving operation 16, i.e., no longer belongs to or is coordinated with the platoon 15.

[0038] For this purpose, the radio channel 27 of the radio network 17 can be used. The radio channel 27 can be a frequency range. The emergency message can be transmitted into the radio channel 27 at a time t. In Figure 1 is shown exemplarily how the radio channel 27 can be formed at a time t and a frequency f. For the radio network 17, it can be provided or prescribed that the emergency message 21 is transmitted into the radio channel 27 in a time slot 28, which can be obtained by the radio standard used.

[0039] Figure 1 It is shown how this can occur, namely that at the moment or time period in which the motor vehicle 23 as the transmitting vehicle 29 has to transmit the emergency message 25 in the radio network 17, another motor vehicle as a further participant 30 of the radio network 17 has already issued a normal message 31. The normal message means that the participant 30 can occupy the radio channel 27 itself, as obtained from the protocol or radio standard of the radio network 17. Thus, when the transmitting vehicle 29 has to transmit its emergency message 25 to the remaining motor vehicles, the radio channel 27 is occupied by the normal message 31. In order to distinguish here, the remaining motor vehicles 10 are referred to as receiving vehicles 33. In the motor vehicles 10, it can be achieved here by the design of the control circuit 19 that the emergency message 25 can still be issued without delay, that is to say without waiting until the normal message 31 no longer occupies the radio channel 27.

[0040] Figure 1 It is explained how the superposition of the normal message 32 and the emergency message 25 is produced in the mentioned time slot 28 at a time t by the transmitting vehicle 29 using its transmitting circuit 20 by simultaneously transmitting the emergency message 25 superimposed or superposed with the normal message 32. For example, in terms of time slots, the entire time slot 28 can be provided not only for the normal message 32 but also for the emergency message 25. In the frequency range, the two messages (normal message 31 and emergency message 25) can also at least partially intersect.

[0041] Figure 2 It is explained how the emergency message 25 can still be received in each of the receiving vehicles 33 by the receiving circuit 22. In a step S10, the transmitting circuit 20 can receive the emergency message 25. The emergency message 25 is explained here by way of example with message data in the form of an image sequence. While the normal message 31 as the transmitting signal 35 of the participant 30 is contained in the radio channel 27, the transmitting signal 37 of the emergency message 25 can also be issued by superposition 36 or superimposition. Thereby, a superposition signal 38 (superimposition signal) is obtained. At this point, the transmission level 39 of the transmitting signal 37 of the emergency message 25 is selected to be lower than the transmission level 40 actually provided for the transmitting circuit 20 for issuing the normal message.

[0042] In step Sll, the superimposed signal 38 can be received by the respective receiving circuit 22 of the receiving vehicle 33. The superimposed signal is formed by a mixture or superimposition of the transmission signal 35 of the normal message, the transmission signal 37 of the emergency message 25 and the channel noise or noise signal.

[0043] However, since the transmission signal 35 of the normal message 31 is dominant, in step S12 it can be decoded by the receiving circuit 22, wherein the emergency message 25, that is to say its transmission signal 37, is treated as noise. Thereby, the normal message 31 can be reconstructed, resulting in a reconstructed normal message 42. The data of the reconstructed normal message 42, that is to say of the normal message, can be used to generate an artificial or copied transmission signal 43. To this end, the conversion of the data of the normal message 31 into an analog radio signal can be imitated, for which a digital model of the conversion process, for example as copied in the transmission circuit 20, can be used. Thereby, the signal course and / or signal spectrum of the normal message 31 is provided as the copied transmission signal 43. In step S13, the copied transmission signal 43 can be removed or subtracted from the received superimposed signal 38, for example by means of a subtraction 44. Thereby, the difference between the (ideal) copied transmission signal 43 and the superimposed signal 38 is obtained. The difference represents a residual signal 45, which still contains noise and the transmission signal 43 of the emergency message 25. Here, too, the level 46 of the copied transmission signal 43 can be matched to the reception level 47 of the superimposed signal 38.

[0044] In step S14, the emergency message 25, that is to say the data of the emergency message, can be decoded in a further decoded manner on the basis of the residual signal 45.

[0045] Thus, in the receiving circuit 22 there is not only the normal message 41, but also the emergency message 25.

[0046] Subsequently, the driver assistance function 14 of the receiving vehicle 33 can be configured or adapted in terms of the emergency message, that is to say taking into account that the transmitting vehicle 29 no longer participates in the cooperative driving operation 16. For example, a safety distance to the transmitting vehicle 29 can be preset and / or taken into account, for example when planning a trajectory, the transmitting vehicle 29 being considered as a non-cooperative road user.

[0047] That is, the idea is to emit the emergency message 25 in synchronization with the normal message of the other participant occupying the radio channel. It is provided to emit the emergency message with a lower power than according to the radio standard and furthermore with the maximum available redundancy. In order to adjust the lower power, for example a modem driving the transmitting circuitry can be switched off and / or the vehicle antenna compensator can be switched off. Preferably, here 6 to 10 decibels are reduced compared to the normal message according to the V2X communication standard. In order to obtain stability or redundancy, the lowest modulation and coding scheme, MCS, can be used. Here, the MCS scheme is understood to be for the mobile radio standard LTE, but other MSC configurations can also be provided. In the case of NR-V2X, the most stable numerology can be used. If possible, a rateless coding scheme on a higher communication layer, for example the application layer or the network layer, can also be specified for multiple transmissions in the same occupied radio channel.

[0048] For a receiving vehicle in the radio network, this results in a superimposed or superposed signal of the normal message used and the simultaneously transmitted emergency message. Thereby, a phase change (leaving the coordinated driving operation) can be reported by the emergency message simultaneously with the normal message in the transmitting vehicle 29. The respective receiving circuit of the receiving vehicle can perform the signal superposition according to the steps S11 to S14 described by a hierarchical decoding or an iterative decoding with feedback in the form of a duplicated transmitted signal. This corresponds to a decoding according to the decision feedback decoding type. Thereby, it can be recognized whether an emergency message is present in addition to the normal message in the time slot 28.

[0049] Preferably, as short a message (data quantity) as possible is used as the emergency message, i.e. the duration for transmitting the emergency message corresponds to the duration of a time slot or is shorter than this duration together with the duration in the redundancy bits. In the normal message or normal message according to the V2X standard, for example the BSM (basic safety message), a data quantity of 120 bytes can be achieved, so that a message which is much shorter, for example less than 40 bytes, can be transmitted as the emergency message in the time slot 28 together with the corresponding redundancy. If a synchronized data transmission is provided, the time offset between the normal message and the emergency message can be selected according to a specification, which can be known not only in the transmitting vehicle 29 but also in each receiving vehicle 33, so that the header of the emergency message can be purposefully searched for or detected in the remaining signal 45. If no such header is detected at a predetermined position in the time slot, in particular at the beginning of the time slot, it can be assumed that no emergency message is contained in the time slot.

[0050] V2X communication does not use a central planning unit, but the participants have to find out whether a radio channel is occupied or free. C-V2X and 5G NR-V2X use semi-persistent planning, in which the devices monitor the channel by measuring. Before transmitting the information 21, it is known in the transmitting circuit whether the channel is occupied or free.

[0051] If an emergency message 25 has to be sent, the vehicle is most likely in one of the following situations: the vehicle has to inform other vehicles that it is changing from a cooperative driving operation to a solo maneuver, or the V2X radio channel is occupied because an unexpected situation has arisen and multiple vehicles are trying to communicate. What is needed is a message to all vehicles in the surroundings, despite the radio channel being occupied.

[0052] The examples in general show how phase transitions can be provided in a complex V2X communication process.

Claims

1. A method for transmitting an emergency message (25) from a sending vehicle (29) to at least one receiving vehicle (33) via a radio network (17), while in a radio channel (27) of the radio network (17) a normal message (31) has already been issued by a radio network participant (30) different from the sending vehicle (29), wherein In the method, - a transmitting circuit (20) of a transmitting vehicle (29) emits an emergency message (25) in a radio channel at a transmission level (39) which is lower than a transmission level (40) of normal messages (31), wherein, for adjusting the transmission level (39) of the emergency message (25), a modem of the transmitting circuit (20) is manipulated and / or an antenna compensation circuit is switched off; - a corresponding receiving circuit (22) of at least one receiving vehicle (33) receives from the radio channel (27) a superimposed signal (38) which contains the normal messages (31) and the emergency message (25), reconstructs the normal messages (31) from the superimposed signal (38), models a signal component of the normal messages (31) in the superimposed signal (38) from the reconstructed normal messages (42), determines a residual signal (45) which describes a difference between the superimposed signal (38) and the modelled signal component from the superimposed signal (38) and the modelled signal component of the normal messages (31), reconstructs the emergency message (25) from the residual signal (45); wherein, in the radio network (17), the normal messages (31) are transmitted in preset time slots (28) of a synchronous data transmission, and the transmitting circuit (20) emits the emergency message (25) with a predetermined time offset relative to a start time of the time slots (28), and, for checking whether the emergency message (25) is contained in the superimposed signal (38), the receiving circuit (22) checks a signal section in the superimposed signal (38) which corresponds to the start time of the time slots (28) plus the predetermined time offset, in order to determine whether a predetermined header of a possible emergency message (25) is present; wherein the emergency message is a message whose content is already known in the receiving circuit.

2. The method of claim 1, wherein, For modelling the signal component from the message data of the reconstructed normal messages (42), a copy of the transmitting signal (43) of the participant (30) is made, the copied transmitting signal (43) is matched to a reception level (47) which the superimposed signal (38) has at the receiving circuit (22), in order to determine the signal component.

3. The method of any of the above claims, wherein, In the radio network (17), a plurality of modulation and coding schemes and / or numerologies are provided for transmitting the normal messages (31), and from among them a coding and / or rateless coding scheme with the greatest redundancy is used for the emergency message (25).

4. The method of any of the above claims, wherein, The transmission level of the emergency message (25) is adjusted to be 6 to 10 decibels lower than the transmission level (40) of the normal messages (31).

5. The method of any of the above claims, wherein, The transmitting vehicle (29) and the at least one receiving vehicle (33) operate the radio network (17) as an AdHoc network for a coordinated driving operation (16), the emergency message (25) reports that the transmitting vehicle (29) interrupts the coordinated driving operation and / or leaves the AdHoc network.

6. A transmitting circuit (20) for a motor vehicle (10), wherein The transmitting circuit (20) has a control device which is set up to transmit a message which is characteristic of an emergency into a radio channel (27) of a radio network (17) and to detect there whether the radio channel (27) is occupied by a transmission of a normal message (31) of another participant (30) and in this case to emit the message as an emergency message (25) in the radio channel (27) at a transmission level (39) which is lower than the transmission level (40) of the normal message (31), in order to adjust the transmission level (39) of the emergency message (25) the modem of the transmitting circuit (20) and / or the antenna compensation circuit are manipulated, wherein in the radio network (17) the normal messages (31) are transmitted in predetermined time slots (28) of a synchronous data transmission and the transmitting circuit (20) emits the emergency message (25) with a predetermined time offset relative to the start time of the time slot (28), wherein the emergency message is a message whose content is already known in the receiving circuit.

7. Motor vehicle (10) with a transmitting circuit (20) according to claim 6.

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