METHOD FOR TRANSMITTING SYNCHRONIZATION INFORMATION IN A COMMUNICATIONS DEVICE, COMMUNICATIONS DEVICE AND VEHICLE

Description

[0001] The invention relates to a method for transmitting synchronization information in a communication device having at least two transceiver units. The invention also encompasses a communication device having at least two transceiver units and a vehicle having a communication device.

[0002] According to the current state of the art, locking systems in vehicles increasingly feature communication devices designed to enable unlocking or locking of a vehicle via radio signals. These communication devices generally use ultra-wideband (UWB) technology for this purpose. To unlock or lock the vehicle wirelessly, the communication device communicates with a device carried by the driver of the vehicle. The device can be, for example, a radio key or a smartphone with a UWB interface. It is common practice for vehicles to only be able to be unlocked or locked from predetermined positions relative to a particular vehicle. For example, it may be required that the device must be located in a predetermined area in front of a vehicle door.

[0003] In order to enable unlocking or locking depending on the position of the device unit in relation to the vehicle, it is common for the position of the device unit to be located via UWB signals by the communication device. The location of the device unit is usually achieved by determining the time of flight of the UWB signals exchanged between the communication device and the device unit. In order to be able to determine the position of the device unit via time of flight determinations, the communication device has several transceiver units, which are also referred to as anchors. These transceiver units are arranged at different positions on the vehicle. By recording the time of flight between the device unit and the respective transceiver units, it is possible to determine the exact position of the device unit.

[0004] In order to minimize energy consumption of the device unit and the communication device, it is common practice to assign predetermined time windows to the individual transceiver units, during which the transceiver units are set to receive and can receive UWB radio signals. Outside of the time windows, the transceiver units are not set to receive and cannot receive UWB radio signals. These time windows are defined by a distance measurement time grid specified by the device unit, with each of the transceiver units being assigned a respective time slot in the distance measurement time grid. Because the UWB signals can only be received by the respective transceiver unit within the assigned time window, precise temporal synchronization between the device unit and the individual transceiver units is required.

[0005] This synchronization is necessary because the device unit and the individual transceiver units of the communication device are located in different time zones. The time zones are specified for the device unit by the device clock, and for the transceiver units by a device clock of the communication device. The clocks usually comprise a respective oscillating quartz crystal. Deviations between the time zones can occur due to runtime differences between the device clocks, which are attributable to the different quartz crystals. In order to ensure synchronization over a period of time, it is necessary to regularly update synchronization information that links the time zone of the device unit with the time zone of the transceiver units and to pass this information on to the individual transceiver units. An example of the prior art is US 2007 / 014339.

[0006] It is therefore an object of the invention to provide a method which enables synchronization by forwarding synchronization information in the communication device.

[0007] A first aspect of the invention relates to a method for transmitting synchronization information in a communication device having at least two transceiver units. The communication device can, in particular, be a communication device for transmitting and receiving UWB radio signals. The communication device can be provided to transmit and / or receive the UWB radio signals in order to enable radio-based locking and unlocking of a locking device of a vehicle. The at least two transceiver units can be arranged at different locations on the vehicle.The transceiver units can be provided to receive the UWB radio signals from an external device unit, which can be, for example, a mobile phone or a radio key, and to determine a distance between the respective transceiver unit and the device unit from a signal strength and / or a propagation time of the UWB radio signals. The communication device can be provided to determine a position of the device unit in a predetermined distance measurement session from the detected propagation times and / or the detected signal strengths at the transceiver units of the UWB radio signals. This distance measurement session is carried out repeatedly. The method provides that the at least two transceiver units are synchronized to a device time zone using a predetermined synchronization method with a device clock of the communication device.In other words, it is provided that the at least two transceiver units are synchronized to a device time zone predetermined by the device clock. The device clock can, for example, be a device having an oscillating quartz crystal. It is provided that, in the predetermined distance measurement session, one of the transceiver units receives a time signal from an external device unit, which comprises a device clock reading of the device unit at a reference time in a device time zone. In other words, it is provided that, in order to determine a distance between the transceiver unit and the device unit, one of the transceiver units receives the time signal, which discloses which device clock reading the device unit has in the device time zone at a predetermined reference time.

[0008] The method provides that, for each distance measurement session, the receiving transceiver unit generates a synchronization data record that describes a time relationship between a device clock reading at the reference time in the device time zone and the device clock reading at the reference time in the device time zone. In other words, the transceiver unit receiving the time signal determines the current synchronization data record. The synchronization data record describes the time relationship between the device clock reading and the device clock reading at the reference time. This determines a relationship between the device time zone and the device time zone.

[0009] The receiving transceiver unit initiates a synchronization session, wherein the receiving transceiver unit defines a synchronization grid comprising a periodically repeating synchronization block comprising a session round. The receiving transceiver unit is intended to initiate a synchronization session. In other words, the receiving transceiver unit is intended to start a synchronization session parallel to the distance measurement session, which synchronization session is intended to enable regular transmission of the current synchronization data record for synchronizing the transceiver units. The receiving transceiver unit defines a synchronization time grid comprising a periodically repeating synchronization block.The synchronization session thus has its own synchronization time grid, which is different from a distance measurement time grid of the distance measurement session. The synchronization block repeats periodically and has the session round. During predetermined session slots of the session round of the periodically repeating synchronization block, the synchronization data record is transmitted to the other transceiver units. In other words, it is intended that a regular transmission of synchronization data records takes place by the transceiver unit. The synchronization data record is transmitted to the other transceiver unit in a predetermined session slot of the session round. The transceiver units are configured to be set up to receive and / or send the synchronization data record in the session rounds and / or the session slots.During this time, the reception and / or transmission of the synchronization data set can be deactivated. The invention provides the advantage that a separate synchronization session is established for synchronizing the transceiver units, which is independent of the distance measurement session. A particular advantage is that the duration of the session slots of the distance measurement session is not extended by the transmission of the synchronization data set.

[0010] The invention also includes further developments which result in further advantages.

[0011] A further development of the invention provides that the at least one further transceiver unit is set to a receive mode by the receiving transceiver unit upon initiation of the synchronization session in order to receive the synchronization data record. In other words, it is provided that the other of the transceiver units is set to the receive mode at the beginning of the synchronization session, in which the at least one further transceiver unit is continuously configured to receive the synchronization data record. The transceiver units can be set to the receive mode by transmitting a predetermined signal. The other of the transceiver units can thus continuously receive the first synchronization data record throughout the entire receive mode.The receiving transceiver unit sends the synchronization data record to the other transceiver unit in the predetermined session slot of the session round of the periodically repeating synchronization block. The other transceiver unit receives the synchronization data record and, using a predetermined coordination process, derives the synchronization time frame from the predetermined session slot. In other words, the other transceiver unit receives the synchronization data record from the receiving transceiver unit in receive mode. From a time of reception, the other transceiver unit can determine the synchronization time frame that will be used in the synchronization session. This informs the other transceiver unit how the synchronization time frame is structured and which predetermined session slot has been assigned to it.The synchronization time frame allows the other transceiver unit to determine the time at which the next session round of the synchronization time frame begins. This extension offers the advantage that the synchronization time frame can be transmitted to the other transceiver unit by transmitting a simple signal.

[0012] A further development of the invention provides that the receive mode is deactivated by at least one further transceiver unit after receipt of the first synchronization data record and is activated in a subsequent session round of the periodically repeating session block. In other words, the receive mode of the further transceiver unit is deactivated as soon as it has received the first synchronization data record. This is possible because the synchronization time grid was transmitted to it through the time of receipt of the first synchronization data record. It can therefore deduce at which time of the next session block the further synchronization data record will be transmitted. To save energy, the receive mode is only activated in a subsequent session round of the periodically repeating session block.This has the advantage that the additional synchronization data records can be received without a continuous reception mode having to be activated.

[0013] A further development of the invention provides that one of the transceiver units receives a respective additional time signal from a further external device unit, which comprises the respective device clock reading of the respective additional device at a respective additional reference time in the device time zone. It is provided that the transceiver unit generates a respective additional synchronization data record that describes a respective time relationship between the device clock reading at the respective additional reference time in the device time zone and the respective additional device clock reading at the respective additional reference time in the respective additional device time zone.The transceiver unit transmits the synchronization data set to the other transceiver units in a predetermined further session slot of the session round of the periodically repeating synchronization block. In other words, it is provided that a further time signal is received by one of the transceiver units. This further time signal, like the time signal of the first device unit, can describe the respective device clock status of the further device at a further reference time in the device time zone. For the device time zone of the further device unit, the transceiver unit can generate a further synchronization data set, which can describe the respective time relationship between the device clock status at the respective further reference time in the device time zone and the respective further device clock status.It is possible for the additional synchronization data record to be transmitted during the synchronization session. For this purpose, a separate session slot in the session round is assigned to the additional synchronization data record in the synchronization grid for transmission. It is thus possible to enable the transmission of additional synchronization data records from respective transceiver units by assigning the additional transceiver units respective session slots in the session round for transmitting the synchronization data records they generate.

[0014] A further development of the invention provides that in the synchronization data record, the device clock reading at the reference time in the device time zone is specified as a block index of a synchronization block of the distance measurement session beginning or ending at the reference time. In other words, the time of the reference time in the device time zone is not specified by a time value, but by the index of the block that begins or ends at the reference time of the distance measurement session. This results in the advantage that the device clock reading is specified by a value that is smaller than a time. The assignment of the device clock reading to a block index is possible because a distance measurement time grid of the distance measurement session is predetermined by the device time zone of the device unit.

[0015] A further development of the invention provides that the synchronization data record transmitted by one of the transceiver units is received by a transceiver unit of the transceiver units acting as a relay transceiver unit, and is sent by the transceiver unit of the transceiver units acting as a relay transceiver unit to the other of the transceiver units. In other words, it is provided that an indirect transmission of the synchronization data record transmitted by one transceiver unit to another of the transceiver units can take place via a transceiver unit acting as a relay transceiver unit. This results in the advantage that the synchronization data record can be delivered to the transceiver unit even if direct transmission of the synchronization data record from the transmitting transceiver unit is not possible.A direct transmission between two of the transceiver units may, for example, be temporarily or permanently impossible. To still enable transmission of the synchronization data record, it can be provided that the transceiver unit that generated the synchronization data record sends the synchronization data record in a first step to the transceiver unit that is to act as a relay transceiver unit. The transceiver unit acting as a relay transceiver unit can, in a second step, forward the synchronization data record it has received to the transceiver unit that is to receive the synchronization data record. It can also be provided that the synchronization data record is forwarded via more than one of the transceiver units. The number of relay transceiver units that have forwarded the data record can be specified as the value of a relay counter.

[0016] A further development of the invention provides that the synchronization data record has an age value, wherein the age value describes a number of blocks since the generation of the synchronization data record. In other words, the age value describes the number of blocks of the synchronization time frame before which the respective synchronization data record was generated. This further development results in the advantage that a reliability and / or timeliness of the respective synchronization data record can be determined. The transceiver units can thus, for example, adapt a duration of the periods in which they are in receive mode depending on the reliability and / or timeliness of the synchronization data record.For example, it can be provided that a safety time window, which describes a period before and / or after a time slot in which the receive mode is additionally activated, has a length that depends on the age value of the synchronization data record. This can, for example, compensate for the fact that a synchronization that occurred longer ago is less accurate than a current synchronization.

[0017] A further development of the invention provides that a renewed synchronization data record is received by one of the transceiver units, and the age value of the renewed synchronization data record is compared with an age value of a synchronization data record stored in the transceiver unit. In other words, the received or generated synchronization data record is stored by the transceiver unit. This synchronization data record has the respective age value. If the renewed synchronization data record is received by the transceiver unit, the age value of the renewed synchronization data record is compared with the age value of the stored synchronization data record. In other words, the method allows the transceiver unit to determine which of the synchronization data records available to it is older.The synchronization record stored in the transceiver unit is intended to be overwritten by the new synchronization record if the age value of the new synchronization record is younger than the age value of the synchronization record. In other words, the stored synchronization record is overwritten by the new synchronization record if the new synchronization record is younger than the stored synchronization record. This provides the advantage that a stored synchronization record is only overwritten by a new synchronization record if the new synchronization record is younger than the stored synchronization record.This ensures that if an older synchronization data record is forwarded via several relay transceiver units, the replacement of a younger data record stored in the transceiver unit by an older data record is prevented.

[0018] A second aspect of the invention relates to a communication device comprising at least two transceiver units. The communication device can be, for example, a radio device of a locking system of a vehicle. The at least two transceiver units can be configured to send and / or receive radio signals during a distance measurement session in order to determine a distance to a device unit. The communication device is configured to synchronize the at least two transceiver units to a device time zone using a predetermined synchronization method with a device clock of the communication device. In other words, the communication device has a device clock configured to specify a device time zone.The communication device is configured to synchronize the at least two transceiver units with the device clock, so that the two transceiver units operate in the device time zone specified by the device clock. The communication device is configured to receive, through one of the transceiver units, a time signal from an external device unit in a predetermined distance measurement session, which time signal comprises a device clock reading of the device unit at a reference time in a device time zone. In other words, it is provided that the transceiver unit is configured to carry out the predetermined distance measurement method in a predetermined distance measurement session in order to determine a distance between the transceiver unit and an external device unit. The external device unit can be, for example, a radio key or a mobile phone.The transceiver unit is configured to receive the time signal received from the device unit. The time signal comprises a device clock reading of a device clock of the device unit at a reference time in the device time zone. In other words, the time signal has a reading of a device clock of the device unit. The device clock reading was read at a reference time. However, the device time zone can differ from the device time zone. In order to enable the two clock readings to be assigned to one another, it is provided that the communication device is configured to generate, via the receiving transceiver unit, a synchronization data record that describes a time relationship between a device clock reading at the reference time in the device time zone and the device clock reading at the reference time in the device time zone.In other words, the transceiver unit is configured to create the synchronization data record, which enables an assignment of the device time zone to the device time zone. For this purpose, the synchronization data record has the time relation, which includes the device clock reading, which is provided by the device clock in the device time zone at the reference time, and assigns the device clock reading of the device time zone to this time. The communication device is configured to initiate a synchronization session via the receiving transceiver unit, wherein a synchronization time grid is defined by the receiving transceiver unit, which synchronization time grid has a periodically repeating synchronization block.In other words, the communication device is configured to transmit the synchronization data set from the generating transceiver unit to the other transceiver units using the predetermined synchronization session, wherein the transmission takes place in the synchronization session, which has a predetermined synchronization time frame. The synchronization time frame has the predetermined synchronization block, which is divided into individual session rounds. The communication device is provided for transmitting the synchronization data set to other transceiver units by the receiving transceiver unit in the predetermined session slot of the session round of the periodically repeating synchronization block.In other words, it is provided that in the session slot assigned to the transceiver unit, the synchronization data record is sent by the transceiver unit to the other of the transceiver units.

[0019] A third aspect of the invention relates to a vehicle having a communication device. The vehicle can, for example, be a passenger car with a locking device that can be configured to unlock a door of the vehicle depending on a located position of a device unit.

[0020] The invention also includes further developments of the communication device according to the invention and the vehicle according to the invention, which have features as already described in connection with the further developments of the method according to the invention. For this reason, the corresponding further developments of the communication device according to the invention and the vehicle according to the invention are not described again here.

[0021] The invention also includes combinations of the features of the described embodiments.

[0022] An embodiment of the invention is described below. It shows: Fig. 1 a schematic representation of a vehicle having a communication device; Fig. 2 a schematic representation of a synchronization time grid and several distance measurement time grids for respective distance measurement sessions; Fig. 3 a schematic representation of a division of the synchronization grid; Fig. 4 a schematic representation of a possible structure of the transmitted synchronization data records; Fig. 5 possible transmission paths between individual transceiver units, whereby direct transmissions can take place between two of the transceiver units; Fig. 6 a schematic representation of existing direct connections between the transceiver units; and Fig. 7 a schematic representation of a process for transmitting synchronization data records in a so-called relay procedure.

[0023] The exemplary embodiment explained below is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual, independently considered features of the invention, which also further develop the invention independently of one another and are thus also to be considered as components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiment can also be supplemented by further features of the invention already described.

[0024] The device unit and the transceiver units can have a computing unit. A computing unit can be understood, in particular, as a data processing device; the computing unit can therefore, in particular, process data to perform computing operations. This may also include operations for performing indexed access to a data structure, for example, a look-up table (LUT).

[0025] The computing unit may, in particular, contain one or more computers, one or more microcontrollers, and / or one or more integrated circuits, for example, one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), and / or one or more single-chip systems (SoCs). The computing unit may also contain one or more processors, for example, one or more microprocessors, one or more central processing units (CPUs), one or more graphics processing units (GPUs), and / or one or more signal processors, in particular one or more digital signal processors (DSPs). The computing unit may also include a physical or virtual network of computers or other of the aforementioned units.

[0026] In various embodiments, the computing unit includes one or more hardware and / or software interfaces and / or one or more memory units.

[0027] A memory unit can be a volatile data memory, for example, a dynamic random access memory (DRAM) or a static random access memory (SRAM), or a non-volatile data memory, for example, a read-only memory (ROM), a programmable read-only memory (PROM), an erasable read-only memory (EPROM), an electrically erasable read-only memory (EEPROM), a flash memory (FRAM), a ferroelectric random access memory (FRAM), a magnetoresistive random access memory (MRAM), or a phase-change random access memory (MRAM).PCRAM (phase change random access memory)

[0028] In the figures, functionally identical elements are provided with the same reference numerals.

[0029] Fig. 1 shows a schematic representation of a vehicle 1 having a communication device 2. The communication device 2 can have transceiver units TRX, which can be configured to send predetermined distance measurement signals 4 to a device unit 5 and / or to receive them from the device unit 5 in order to be able to determine a distance between a respective transceiver unit TRX and the device unit 5 in a predetermined distance measurement session S. It can be provided that the distance measurement signals 4 are sent and / or received by the respective transceiver units TRX in respective distance measurement time windows 6. The distance measurement time windows 6 can be predetermined in a distance measurement time grid of the distance measurement session S7.It can be provided that the respective transceiver units TRX can only be set to a distance measurement reception mode in their respective distance measurement time windows 6 of the distance measurement time grid 7 in order to save energy. To determine the distance measurement time windows 6, the communication device 2 can have a device clock 8, which can specify a device time zone 9. The device clock 8 can be configured, for example, as a quartz clock. The individual transceiver units TRX can be synchronized with the device clock 8 and thus operate in the same device time zone 9. The device unit 5 can have a device clock 10, which can specify a device time zone 11, 14.In order for the device unit 5 to transmit a distance measurement signal 4 and the respective transceiver unit TRX to receive the distance measurement signal 4 within its assigned distance measurement time window 6, it may be necessary for the device unit 5 to be synchronized with the transceiver units TRX 4. This may result in the problem that there may be a time difference between the device time zone 11, 14 of the device unit 5 and the device time zone 9 of the communication device 2, which may result from different runtimes of the quartz crystals of the device clock 10 and the device clock 8. In order to maintain synchronization between the communication device and the device unit 5, it may therefore be necessary for regular synchronizations to take place between the communication device 2 and the device unit 5.According to the prior art, a time signal 12 is sent by the device unit 5 to a transceiver unit TRX4 acting as a master transceiver unit TRX. The time signal 12 can include a device clock reading 13 of the device clock 10 of the device unit 5 at a reference time T in the device time zone 11, 14. The transceiver unit TRX4 can receive the time signal 12 and generate a synchronization data record 15 that describes a time relationship between the device clock reading of the device clock 8 at the reference time in the device time zone 9 and the device clock reading 13 of the device clock 10 at the reference time in the device time zone 11, 14. This makes it possible to specify the reference time in both time zones. It may be necessary for the synchronization information in the synchronization data record 15 to be transmitted to the other of the transceiver units TRX 4.This can be done, for example, via radio. However, it must be ensured that a collision between synchronization time windows 16 of a synchronization session does not collide with the distance measurement time windows 6 of the distance measurement session S. A further problem may arise from the fact that, in the case where multiple device units 5 communicate with the communication device 2, an unnecessarily high increase in the data volume for synchronizing the individual transceiver units TRX must be avoided.

[0030] It is therefore provided that the synchronization session is initiated by the master transceiver unit TRX of the transceiver units TRX. The master transceiver unit TRX defines a synchronization time grid 17, which has a periodically repeating synchronization block 18. The synchronization block 18 itself has a session round 19 in which session slots 20 are arranged, with each of the session slots 20 being assigned to a respective transceiver unit TRX. It is provided that in the respective session slots 20, the transceiver units TRX predetermine the synchronization time windows in which the respective synchronization data records 15 are sent, and the transceiver units TRX are set to a synchronization receive mode for receiving the synchronization data records 15.

[0031] Fig. 2 shows a schematic representation of a synchronization time grid 17 and several distance measurement time grids for respective distance measurement sessions S. Shown are the distance measurement time grids "UWB Device Time" defined by the respective device units 5, which define the distance measurement time windows 6 in which, during the distance measurement sessions S, distance measurement signals 4 can be exchanged between the respective device unit 5 and the communication device 2 of the vehicle 1, and the transceiver units TRX can be set to a distance measurement reception mode. Additionally, the synchronization time grid 17 "Vehicle Time" defined by the master transceiver unit TRX, to which all transceiver units TRX are synchronized, is shown. The distance measurement sessions S S1 to S4 can be assigned to a respective device unit 5.A distance measurement time grid of each of the distance measurement sessions S can be predetermined by the device time zone 11, 14 of the respective device unit 5. The distance measurement time grids of the respective distance measurement sessions S can have predetermined blocks, each of which can have a predetermined duration. Within a block, a respective round can be arranged, in which a distance measurement between the respective device unit 5 and the individual transceiver units TRX can be carried out by exchanging distance measurement signals 4. For each additional device unit 5, it may be necessary to generate respective synchronization data records 15, which must be sent by one of the transceiver units TRX to the other transceiver units TRX.For this purpose, it is necessary to provide a method that avoids an excessive increase in the amount of data transmitted and the resulting increased risk of a collision between distance measurement time windows 6 of different distance measurement sessions S and synchronization time windows 16. It is therefore provided to initiate the predetermined synchronization session, in which the respective synchronization data sets 15 required for the individual distance measurement sessions S are exchanged between the transceiver units TRX. The synchronization grid can be specified by the master transceiver unit TRX and have a predetermined duration. Each block can have a respective round in which the synchronization data sets 15 can be transmitted and received in respective slots by the individual transceiver units TRX. The synchronization time grid 17 is specified by the master transceiver unit TRX.This can, for example, be the transceiver unit TRX that initiated the first distance measurement session S with one of the device units 5. In order to be able to communicate the synchronization time frame 17 to the other transceiver units TRX, it can be provided in a first step that the other transceiver units TRX are placed into a permanent synchronization receive mode by the master transceiver unit TRX. While the other transceiver units TRX are in synchronization receive mode, the master transceiver unit TRX can send the first synchronization data set 15 to the individual transceiver units TRX.Since each of the transceiver units TRX is assigned a predetermined synchronization slot of the synchronization time grid 17, the transceiver units TRX can determine the synchronization time grid from the time of reception of the first synchronization data set 15 and thus determine the future reception times. After receiving the first synchronization data set 15, the individual transceiver units TRX can enter the synchronization reception mode during the respective session slots 20 and deactivate the synchronization reception mode during a remaining session slot.

[0032] The idea concerns the internal transmission of synchronization information (vehicle internal sync), which a transceiver unit (TRX), also known as an anchor, receives either through the reception of a UWB packet or through the process known as "BLE Timesync." Both mechanisms are described in the CCC specification and provide the anchor with information about the current time (UWBDeviceTime) in the time zone of the smartphone device.

[0033] One goal of the method is to transmit local temporal synchronization information into a synchronization data record 15, which can be transmitted to other transceiver units TRX in a time-independent manner. The synchronization data record 15 can have data tuples that assign a device clock state of the device time zone 9 "Vehicle Time" to the device clock state 13 "Clock State" of the device time zone 11, 14 "UWB Device Time". The synchronization data record 15 can also include supplementary information. This supplementary information can include an uncertainty value Uncertainty and a source value S ID . The source value S ID can identify the transceiver unit TRX that generated the synchronization data record 15.

[0034] It is intended that all transceiver units TRX of the communication device 2 are synchronized with the device clock 8 of the communication device 2. The transceiver units TRX can thus be assigned to the device time zone 9 defined by the device clock 8. The device clock 8 can be synchronized by a control unit via a bus system or by a UWB session of the transceiver units TRX. A transceiver unit TRX therefore has two clocks acting as clock masters: the device clock 10 Device Clock and the device clock 8 Vehicle Clock. Any arbitrary point in time t can be represented by a clock state Clock State in the two time zones: C_Devicet, C_Vehiclet. The synchronization data record 15 can be distributed from the creating transceiver unit TRX to all other transceiver units TRX via a bus system, for example the CAN bus.This can be done, for example, via direct distribution or central distribution via a vehicle's ECU 1. Another option is radio-based distribution via UWB "UWB Timesync" or via other relay channels such as BLE or WLAN. During distribution, a cyclical update of the synchronization data set 15 can be provided.

[0035] The format of synchronization data record 15 can be compressed by omitting redundant or implicit information. For example, synchronization data record 15 can specify the relationship between the clock states as the offset between the clock state of device clock 10 and the clock state of device clock 8: OffsetV − Dt = C_Vehiclet − C_Devicet

[0036] The clock status of the device clock 10 can be represented via a distance measurement time grid of the distance measurement session S MAC-Grid. In this case, the time can be converted to a fixed reference of the MAC-Grid block or round level. The MAC-Grid variables of the distance measurement time grid of the distance measurement session S can be transmitted instead of a time. It can be provided that a non-synchronized anchor extrapolates an existing synchronization data set 15 for a current device clock status 13.

[0037] For example, there may be a synchronization data record 15 that assigns the device clock status to the device clock status 13 at a time t1. If a device clock status 13 is required for a later time t2, it can be calculated using the following formula. C_Devicet 2 = C_Vehiclet 2 − C_Vehiclet 1 ∗ C_Devicet 1 ∗ Clock _ skew

[0038] It can be provided that a calculation of an uncertainty range is performed based on the uncertainty value "Uncertainty." In this case, or instead, worst-case assumptions can be made for the relative rate difference "Clock_skew" between the device clock 10 and the device clock 8. An estimate of the relative rate difference between the device clock 10 and the device clock 8 can be made based on multiple synchronization data sets 15. The synchronization data set 15 can be distributed via the CAN bus.

[0039] Another possibility is to transmit the synchronization records 15 via UWB "UWB-Timesync".

[0040] In this case, a separate synchronization session can be initiated, which can bundle a distribution of the synchronization data records 15 of all distance measurement sessions S. It can thus be provided that the synchronization session is initiated in addition to the distance measurement sessions S. The synchronization session T can have its own synchronization time grid 17, in which the transceiver units TRX exchange the synchronization data records 15. In this synchronization session, the synchronization data records 15 of different distance measurement sessions S can be exchanged. A distance measurement session S can exist for a respective device unit 5 that is to be located by the communication device 2. The synchronization time grid 17 of the synchronization session can be selected independently of the distance measurement time grids of the distance measurement sessions S.

[0041] To initiate the synchronization session, one of the transceiver units TRX can be designated as the master transceiver unit TRX. This defines the synchronization time grid 17 MAC Grid of the synchronization session. The synchronization time grid 17 of the synchronization session can have the device time zone 9 as a reference. In contrast, the distance measurement time grid of the distance measurement sessions S is defined with respect to the device time zone 11, 14 of the respective device time zone 11, 14.

[0042] The transceiver unit TRX that negotiated a first of the distance measurement sessions S can be designated as the master transceiver unit TRX. The other transceiver units TRX adopt the synchronization time grid 17 defined by the master transceiver unit TRX and are so-called slave transceiver units TRX. The slave transceiver units TRX transmit in the respective time slots assigned to them. A transmission sequence of the transceiver unit TRX can be defined in advance in the communication device 2 or dynamically determined during the initialization of the synchronization session by the master transceiver unit TRX. The initialization of the synchronization session can occur in conjunction with the first distance measurement session S. The same parameters of the physical layer that are used for the distance measurement session S can be used for the synchronization session.The master transceiver unit TRX can start the synchronization time grid 17 MAC Grid, taking into account the start of the distance measurement session S. At the start of the synchronization session, the transceiver units TRX that are slave master transceiver units TRX switch to a continuous synchronization reception mode "scanning" until they receive the first synchronization data record 15 of the synchronization session from the master transceiver unit TRX. Upon reception, the slave master transceiver units TRX can determine the synchronization time grid 17 of the synchronization session. During the synchronization session, the most recent synchronization data records 15 of all distance measurement sessions S can be periodically transmitted. Each of the transceiver units TRX can manage its own table of synchronization data records 15, which can be updated with new synchronization data records 15.The new synchronization data sets 15 can be those that were generated by the transceiver unit TRX itself or received by another of the transceiver units TRX. For new synchronization data sets 15, each of the transceiver units TRX can determine, based on the uncertainty value U, whether the new synchronization data set 15 is more reliable than the existing synchronization data set 15.

[0043] The transceiver units TRX can act as relay transceiver units TRX and forward received synchronization data sets 15 to other transceiver units TRX.

[0044] Each of the transceiver units TRX transmits in the synchronization time slot of the synchronization time grid 17 assigned to it. This can also occur if the master transceiver unit TRX cannot receive directly. Each of the transceiver units TRX can determine the quality of its available synchronization time grid 17 of the synchronization session, which is updated upon receipt of a synchronization session packet.

[0045] The quality of the synchronization time grid 17 of the synchronization session available to the transceiver unit TRX is described by the elapsed time since the receipt of the last known synchronization data set 15 from the master transceiver unit TRX, as well as the number of relay transceiver units TRX that have forwarded the synchronization data set 15 from the master transceiver unit TRX. A synchronization session protocol or a respective synchronization data set 15 stored in a respective transceiver unit TRX can include information about the quality of the synchronization time grid 17 of the synchronization session and an age value of a duration since a last reception from the master transceiver unit TRX (the "Timesync Grid Age"). The synchronization data set 15 can also include a relay counter.This can specify a number of relay transceiver units TRX and describe how many relay transceiver units TRX the synchronization data set 15 has been forwarded to since it was sent by the master transceiver unit TRX "Relay Counter".

[0046] A slave transceiver unit TRX can terminate a periodic transmission of the synchronization data records 15 if no other synchronization data record 15 of the synchronization session has been received for a predetermined period of time, or the age value of the synchronization time grid 17 exceeds a predetermined value.

[0047] The master transceiver unit TRX can terminate the synchronization session when all distance measurement sessions S are finished or the device unit 5 has not been received for a predefined time (timeout).

[0048] Fig. 3 shows a schematic representation of a division of the synchronization grid. Shown is a synchronization block 18 of the synchronization grid, which may comprise multiple synchronization rounds. One of the synchronization rounds comprises multiple synchronization slots, wherein a respective synchronization slot may be assigned to a respective transceiver unit TRX. The sequence of the synchronization slots and the assignment of the transceiver units TRX may be predetermined. A synchronization round may comprise a transmission of synchronization data records 15, which may contain temporal relationships between device time zones 11, 14 and device time zones 9 of all distance measurement sessions S.

[0049] The transceiver unit TRX1 can be the master transceiver unit TRX of the synchronization session and specify the synchronization time frame 17. A designation of one of the transceiver units TRX as the master transceiver unit TRX and an order of the slave transceiver units TRX can be predetermined in the communication device 2, or can be dynamically assigned from synchronization session to synchronization session.

[0050] Each of the transceiver units TRX attempts to receive the synchronization data sets 15 from all other transceiver units TRX in order to obtain the most current time relations Fig. 4 shows a schematic representation of a possible structure of the transmitted synchronization data records 15.

[0051] A synchronization data record 15 can include the time relations per distance measurement session S, as well as information about the time sync layer for the vehicle-side synchronization of the device clock 8.

[0052] The format of the time relations can be adapted to optimize the size of the source data or to omit redundant information. A device clock reading 13 can be extrapolated to the boundaries of a distance measurement session block or a synchronization session block. It is sufficient to transmit an index of the distance measurement session block or the synchronization session block. Device clock readings 13 and / or device clock readings with a comparatively high resolution do not need to be transmitted. It can be provided that, instead of a data tuple from the device clock reading 13 and the device clock reading, only the difference between these two values ​​is transmitted as a time relation ("offset"). Timesync link layer information can be omitted if it is already known through vehicle-side synchronization of the transceiver units TRX with the device clock 8, e.g., vehicle clock synchronization via CAN bus.

[0053] The synchronization data record 15 can comprise a data record header 21, synchronization time grid information 22, and synchronization data 23 of a synchronization session. A synchronization data record 15 for a specific session can, for example, contain a reference to the respective session. The synchronization data records 15 can also contain a current device clock reading UT 13 UT of the device unit 5 and a current device clock reading VTVT of the communication device 2. A respective synchronization data record 15 can also comprise an uncertainty value UU, which can, for example, comprise measurement and / or estimation inaccuracies of a current time. The synchronization data record 15 can also comprise a source value S ID S ID that identifies the transceiver unit TRX that generated the respective data record.A relay counter RCRC can indicate the number of relay transceiver units TRX that have forwarded the synchronization data set 15. A value S can determine the distance measurement session S. A synchronization session identification T ID T ID can identify the synchronization session. An age value AC can indicate an old AC of the synchronization data set 15. A master transceiver unit identification M ID can indicate the master transceiver unit TRX of the synchronization session.

[0054] Fig. 5 shows possible transmission paths between individual transceiver units TRX, whereby direct transmissions can occur between two transceiver units TRX. If distribution takes place via UWB or another wireless medium, there is no guarantee that each transceiver unit TRX can receive the synchronization data set 15 from another transceiver unit TRX at any time. Scenarios can arise where a synchronization data set 15 only reaches a specific transceiver unit TRX with the help of the relay functionality of other transceiver units TRX. Latencies can occur during transmission. In the worst case, one of the transceiver units TRX can be completely isolated from the other transceiver units TRX (an "isolated anchor").

[0055] Fig. 6 shows a schematic representation of existing direct connections between the transceiver units TRX. A possible special case is shown in which each of the transceiver units TRX can only send synchronization data sets 15 via a direct connection to another of the transceiver units TRX.

[0056] Fig. 7shows a schematic representation of a process for transmitting synchronization data records 15 in a so-called relay process. Synchronization blocks 18 of the synchronization process and individual synchronization slots are shown, with each synchronization slot showing a respective transceiver unit TRX acting as a sender and a respective transceiver unit TRX acting as a receiver of a synchronization data record 15. A number displayed on the arrows can indicate the age value of a respective data record or the number of redirections performed via relay transceiver units TRX.

[0057] It can be provided that in a first synchronization block 18, the synchronization data set 15 is transmitted from a transceiver unit TRX1 to a transceiver unit TRX2. A respective counter of the relay forwardings can be zero. In a second slot, which can be assigned to the second transceiver unit TRX2, a transmission of the synchronization data set 15 can take place from the second transceiver unit TRX1 to the third transceiver unit TRX3 and the first transceiver unit TRX1, whereby the relay counter RC can assume the value 1. In a third slot, the transceiver unit TRX3 can transmit the synchronization data set 15 to the transceiver unit TRX2 and the transceiver unit TRX4. In a fourth slot, the transceiver unit TRX4 can transmit the synchronization data set 15 to the transceiver unit TRX3.

[0058] In the synchronization session block shown below, a connection between the transceiver unit TRX2 and the transceiver unit TRX3 may be interrupted. As a result, a new synchronization data record 15 cannot be received by the transceiver unit TRX3. An outdated synchronization data record 15 may therefore be stored in the transceiver unit TRX3.

[0059] In a third synchronization session block, a connection between transceiver unit TRX2 and transceiver unit TRX3 may still be interrupted. In this synchronization session block, transceiver unit TRX4 may receive synchronization data record 15 from transceiver unit TRX2.

[0060] Overall, the example shows how procedures for passing on synchronization information can be provided. List of reference symbols

[0061] 1Vehicle 2Communication device TRXTransceiver unit 4Distance measurement signal 5Device unit 6Distance measurement time window 7Distance measurement session 8Device clock 9Device time zone 10Device clock 11Device time zone 12Time signal 13Device clock reading 15Synchronization data record 16Synchronization time window 17Synchronization time grid 18Synchronization block 19Session round 20Session slot 21Data record header 22Synchronization time grid information 23Synchronization data of a synchronization session R CRelay counter A CAge value V TCurrent device clock reading T IDSynchronization session identification M IDMaster transceiver unit identification UUncertainty value U TCurrent device clock reading S IDSource value SDance measurement session

Claims

1. Method for forwarding synchronization information in a communication apparatus (2) having at least two transceiver units (TRX), where - the at least two transceiver units (TRX) are synchronized to an apparatus time zone (9) by a predetermined synchronization method using an apparatus clock (8) of the communication apparatus (2), - one of the transceiver units (TRX) receives in respective predetermined ranging sessions (7, S) a time signal (12) from an external device unit (5), which time signal comprises a device clock state (13) of the device unit (5) at a reference time in a device time zone (11, 14), characterized in that - the receiving transceiver unit (TRX) generates at each of the ranging sessions (7, S) a synchronization dataset (15), which describes a time relationship between an apparatus clock state at the reference time in the apparatus time zone (9) and the device clock state (13) at the reference time in the device time zone (11, 14), - the receiving transceiver unit (TRX) initiates a synchronization session, in which the receiving transceiver unit (TRX) defines a synchronization time grid (17) in which a synchronization block (18) is repeated periodically, in which a session round (19) takes place, - the receiving transceiver unit (TRX) transfers in a predetermined session slot (20) of the respective session round (19) of the periodically repeating synchronization block (18) the current synchronization dataset (15) to the others of the transceiver units (TRX).

2. Method according to Claim 1, characterized in that - when the synchronization session is initiated, the receiving transceiver unit (TRX) sets the at least one further transceiver unit of the transceiver units (TRX) to a receive mode in order to receive a first synchronization dataset (15), - the at least one further transceiver unit of the transceiver units (TRX) receives the first synchronization dataset (15) in the predetermined session slot (20) of the session round (19) of the periodically repeating synchronization block (18), - the at least one further transceiver unit of the transceiver units (TRX) derives from the predetermined session slot (20) the synchronization time grid (17) according to a predetermined alignment method, and ascertains a time of a next session round (19).

3. Method according to Claim 2, characterized in that the receive mode is deactivated by the at least one further transceiver unit of the transceiver units (TRX) after receiving the first synchronization dataset (15), and is activated in a next session round (19) of the periodically repeating session block.

4. Method according to Claim 3, characterized in that one of the transceiver units (TRX) receives from a further external device unit (5) a respective further time signal (12), which further time signal comprises the respective device clock state (13) of the respective further device unit at a respective further reference time in the device time zone (11, 14), where - the transceiver unit (TRX) generates a respective further synchronization dataset (15), which describes a respective time relationship between the apparatus clock state at the respective further reference time in the apparatus time zone (9) and the respective further device clock state (13) at the respective further reference time in the respective further device time zone (11, 14), - the transceiver unit (TRX) transfers in a predetermined respective further session slot (20) of the session round (19) of the periodically repeating synchronization block (18) the synchronization dataset (15) to the others of the transceiver units (TRX).

5. Method according to one of the preceding claims, characterized in that in the synchronization dataset (15), the device clock state (13) at the reference time in the device time zone (11, 14) is given as a block index of a synchronization block (18) of the ranging session (7, S), which synchronization block starts or ends at the reference time.

6. Method according to one of the preceding claims, characterized in that the synchronization dataset (15) is received by one of the transceiver units (TRX) that is acting as a relay transceiver unit (TRX), and is sent to the further transceiver unit of the transceiver units (TRX) by the transceiver unit of the transceiver units (TRX) that is acting as the relay transceiver unit (TRX).

7. Method according to one of the preceding claims, characterized in that the synchronization dataset (15) has an age value (A C), where the age value (A C) describes the number of blocks since the synchronization dataset (15) was generated.

8. Method according to Claim 7, characterized in that a fresh synchronization dataset (15) is received by one of the transceiver units (TRX), the age value (A C) of the fresh synchronization dataset (15) is compared with an age value (A C) of a synchronization dataset (15) stored in the transceiver unit (TRX), and the synchronization dataset (15) stored in the transceiver unit (TRX) is overwritten by the fresh synchronization dataset (15) if the age value (A C) of the fresh synchronization dataset (15) is less than the age value (A C) of the synchronization dataset (15).

9. Communication apparatus (2) having at least two transceiver units (TRX), where the communication apparatus (2) is configured to synchronize the at least two transceiver units (TRX) to an apparatus time zone (9) by a predetermined synchronization method using an apparatus clock (8) of the communication apparatus (2), the communication apparatus (2) is configured to receive by one of the transceiver units (TRX) in a predetermined ranging session (7, S) a time signal (12) from an external device unit (5), which time signal comprises a device clock state (13) of the device unit (5) at a reference time in a device time zone (11, 14), characterized in that the communication apparatus (2) is configured to generate by the receiving transceiver unit (TRX) a synchronization dataset (15), which describes a time relationship between an apparatus clock state at the reference time in the apparatus time zone (9) and the device clock state (13) at the reference time in the device time zone (11, 14), - to initiate by the receiving transceiver unit (TRX) a synchronization session, in which the receiving transceiver unit (TRX) defines a synchronization time grid (17) which has a periodically repeating synchronization block (18), which has a session round (19), - to transfer by the receiving transceiver unit (TRX) in a predetermined session slot (20) of the session round (19) of the periodically repeating synchronization block (18) the synchronization dataset (15) to the others of the transceiver units (TRX).

10. Vehicle comprising a communication apparatus (2) according to Claim 9.