Method for optimizing the forwarding data rate in a sensor network during partial network operation in an Ethernet network - Patents.com

Abstract

The method includes the steps of: a) using a head node to determine the number of active nodes; b) using the head node to classify detected nodes into two or more classifications of nodes for prioritizing Ethernet network communications; c) receiving, by the head node, reservation requests from at least some of the plurality of nodes; and d) allocating time slots to one or more nodes in an upcoming communication window in response to the reservation requests, the allocation being based on the priority of the nodes, and priorities being assigned to them according to their classification; once the number of active nodes is determined, a bus cycle length is calculated; the number of sleeping, inactive, or defective nodes is determined; and a beacon bus cycle is determined by finding how much the bus cycle length can be shortened.

Description

[Technical field]

[0001] The present invention relates to a method, a control device and an Ethernet in-vehicle network for optimizing the transmission data rate in a sensor network in partial networking within an Ethernet in-vehicle network of a motor vehicle. [Background technology]

[0002] In addition to 10 Mbit / s (IEEE 802.3ch), other Ethernet standards are becoming available for automotive applications, with 100 Mbit / s, 1000 Mbit / s, and multi-gigabit standards currently in place.

[0003] One variant of the new standard is the CSMA / CD-based multi-drop mode. It is very different from other Ethernet variants (>10Mbit / s) because it pursues the goal that Ethernet can be designed more cost-effectively and therefore can also cope with simpler control devices. This standard does not require any switches (switch ICs) and is designed as a bus (similar to CAN). This roughly halves the number of PHYs (transceivers) required. Ethernet is therefore becoming a formidable competitor to CAN / CAN-FD and FlexRay, since it can significantly reduce the system cost. Furthermore, typical automotive interfaces such as SPI instead of xMII are also possible for the communication between the controller and the physical transceivers (PHYs).

[0004] Figure 1 compares the essential characteristics of switched Ethernet with "bus Ethernet" (multi-drop) as defined in the IEEE standard IEEE P802.3cg. The main difference here is that the resource bus access is available exclusively for switched Ethernet, meaning that any Ethernet node (ECU) can transmit at any time without collisions occurring in the process. A shared media is used in new Ethernet bus implementations with multi-drop mode, i.e. bus access must be withheld until the resource is available.

[0005] The IEEE P802.3cg standard uses, among other things, a newly defined mechanism (PLCA - Physical Layer Collision Avoidance) to avoid collisions during bus access and to implement fair access. In this case, exactly one PHY (Physical Transceiver) receives access to the bus at any one time. This allows collisions to be avoided. Access is done in a so-called round-robin manner. Each ECU (node) on the bus has the opportunity to transmit once within a defined cycle (or sequence).

[0006] A node known as the head node, which assumes the function of a network controller, then identifies the cycle and transmits a "beacon" repeatedly on the bus. The nodes therefore start a timer based on their previously defined identification ID, which identifies the order as to when the nodes are allowed to transmit, and after the timer expires and the node is recognized as the next node, it is allowed to transmit.

[0007] Figure 2 shows the basic flow of communication on an Ethernet bus: after the beacon is transmitted, it is node 0's turn first, and when it finishes its transmission, the next node is allowed to transmit (usually in each case only a single Ethernet frame may be transmitted in a slot).

[0008] FIG. 3 shows a physical representation of an Ethernet bus with stubs.

[0009] EP 2585940A1 describes that a system and method for scheduling network communications in a managed network may comprise a network controller recognizing a plurality of network nodes, which classifies the recognized network nodes into two or more classifications of nodes in order to prioritize network communications at the node level, the network controller receiving reservation requests from at least some of the plurality of network nodes, the reservation requests requesting one or more time slots for their respective network nodes in an upcoming communication window, and the network controller, in response to the reservation requests, assigning time slots in the upcoming communication window to one or more network nodes, the assignment being based on the priorities of the network nodes, the priorities being assigned to the nodes according to their classification. The patent application describes that the network controller creates a cyclic medium access plan (MAP) in which the access behavior of the network nodes is defined in each cycle. The basic principle is the required quality of service, the reservation requests from the respective nodes and their priority / lower priority, from which the network controller creates the MAP. The network controller may also automatically send MAP messages without reservation requests.

[0010] In US 2005 213 503 A1, according to one particular described implementation, the coordinator performs a bandwidth allocation procedure based on information from a previously unfulfilled bandwidth allocation request and responds to a current bandwidth allocation request. The current bandwidth allocation request specifies a currently requested bandwidth amount for multiple streams, and the current bandwidth allocation request may be received from multiple entities having multiple streams. When allocating available bandwidth among multiple streams from multiple entities to the currently requested bandwidth amount, the information from the previously unfulfilled bandwidth allocation request is taken into account. When scheduling bus access for network nodes, "unserved" access reservations from previous cycles are also taken into account by the head node.

[0011] In contrast to a switched network (such as 100 / 1000 etc. Mbit / s), at 10 Mbit / s you cannot get immediate access to the bus as explained, but must wait each time.

[0012] Partial networking (also called sleep / wake-up) is becoming an increasingly important feature for automobiles and also for example Ethernet buses, where control units are woken up (also via the bus) or put to sleep as needed, for example to save energy or to wake up the control units.

[0013] Compared to other Ethernet types, the 10Mbit bus offers significantly lower data rates, so special consideration must be given to data transmission efficiency, transmission latency, and access times. If security also becomes part of a 10Mbit / s system, as is the case with current CAN-FD implementations, there is little data rate remaining for payload data.

[0014] Partial networking functionality requires additional consideration of bus access times and efficiency, as this is a new scenario not considered in the standard.

[0015] Figure 4 illustrates a general problem: for a sleeping or faulty node (control device), bandwidth is wasted / kept available for all nodes. This limits the bus bandwidth and consumes resources unnecessarily.

[0016] The current problem is that the standard only allows for one frame to be transmitted per cycle, and therefore the remaining data rate of each node (here specifically the master node or head node) decreases as the number of participants on the bus increases.

[0017] The head node is implemented either in a head unit, a gateway, a fusion unit, or generally in a zone controller, i.e., typically on the same control unit that also issues update or diagnostic queries.

[0018] It is known to use what is known as a burst mode in which a node can transmit up to 255 packets during the cycle, but this mode must be statically preset and maintained.

[0019] In partially and highly automated driving there are increasing demands on vehicles that require hard real-time support from transmission networks and protocols, as already exists today in aviation or industrial automation.

[0020] Also, vehicle electrical systems will be much more flexible in the future than they are today: nodes can be deactivated during operation if they are not needed (this is also known as partial networking). This in turn means that vehicle electrical systems can change quite dynamically at run time. These features are already being implemented and mass-produced in 2020.

[0021] The aim of the present invention is to accommodate new Ethernet technologies in a cost-optimized manner and with low implementation effort.

[0022] The object is achieved by a method according to claim 1, a control device according to claim 4 and an Ethernet network according to the features of claim 6.

[0023] The present invention advantageously makes new Ethernet technologies suitable for use in automobiles in terms of cost and implementation effort.

[0024] The invention proposes a method to adapt the bus cycle to the data rate requirements of the head node. In other words, more bandwidth may be dynamically allocated to the head node when needed. The invention proposes a method to adapt the bus cycle depending on the data size to be transmitted, in such a way that the download / update requirements regarding transmission time are not violated. The method in this case calculates how much bandwidth must be provided at any given time. However, the method in this process always takes into account the standards and does not need to intervene with other nodes.

[0025] The present invention proposes a method to dynamically adapt the "bus cycle" or transmission time of the beacons to the current and future network behavior, as shown in Figure 5. In other words, the bus is adapted accordingly by removing unused transmission slots and moving them so that other nodes thus receive faster access to the bus, as shown in Figure 6. This may be implemented without additional effort, without new hardware, but only with software and configuration, although not provided up to now.

[0026] The solution and advantage of the method according to the invention consists in the individual shortening and adaptation of the schedule or bus cycle. By transmitting the beacon frame earlier, shown as "B" in Fig. 6, the subsequent bus cycle can always be executed earlier. The transmission slots of the individual nodes may be of a size between 64 and 1522 bytes and are always shown with the same size, purely for the sake of simplicity.

[0027] The quality of execution of sensor-based applications (e.g. autonomous driving, data logger, diagnostics) may be advantageously improved by the present invention. The concept may be implemented without additional financial expenditure (hardware costs) and in compliance with standards.

[0028] The use of newly introduced Ethernet protocols in automobiles requires mechanisms that exploit simple techniques and certain properties of the technology to enable implementation without expensive implementation and additional hardware. The network system according to the invention is improved in terms of reliability. The software-based approach allows Continental to get the best out of its ECUs or networks and provide more functionality to its customers.

[0029] A particular application-specific benefit of more accurate and predictable delays is improved scheduling and execution of communications in vehicles. This means that existing bus systems can be used more efficiently and jumping on board more expensive technologies with higher bandwidth can be avoided. This can also impact the required buffer storage, in which case it can be made unnecessary or smaller. Fusion of different data, for example ultrasonic, radar or microphone, can thereby be improved and made more accurate. Furthermore, data logging can be made even more accurate.

[0030] Today, applications are adjusted and adapted to the platform. The present invention describes a way to allow the software to be designed with some flexibility and to make the most of the underlying system without having to permanently program it into the software in advance. The starting point is what is known as the worst case, which wastes resources and money and impairs quality. The present invention allows software developers and designers to provide software / applications that can be more flexibly and more precisely adapted to the requirements of the application case. By incorporating the aforementioned method into the software, it is possible to perform optimizations on a case-by-case basis or within the control device. This means that the software can be developed in a more platform-dependent manner.

[0031] Partial networking as a system feature is unfortunately necessary in 10 Mbit / s technology, although it would have an even greater impact on the overall system if, for example, bus efficiency were to be affected thereby and controllers no longer wasted time "waiting", which would have an even greater impact on the overall system.

[0032] New technologies can no longer be confined to the automobile. Protocols such as IP, AVB and TSN have thousands of pages of specifications and test suites. It is not currently known whether these new protocols can be controlled in the automobile.

[0033] One advantage of the invention is that no changes to the usual hardware are required, so that existing hardware can continue to be used. The new method can be integrated into existing networks without damaging existing equipment. No standards are violated, since existing protocols can be used. These sensors should be as cheap as possible, especially to supply the mass market. This represents a great added value if more expensive interfaces such as cables / plugs can be eliminated. In addition, the quality of the data is improved the faster it reaches the bus and the less waiting and / or storage is required.

[0034] The proposal solves the problem that the beacon cycle time only depends on the bus and its configuration, and not on the individual nodes or their requirements. A fundamental change in the new architecture is characterized by the centralization of the software in fewer computing units. These so-called servers or central computers no longer consist of just one μC or μP, but also contain several μCs, μPs, SOCs, and Ethernet switches with many ports. They represent separate local area networks, each with separate software, which also means that the respective software components do not (cannot) know that they are communicating with components located, for example, in the same housing. Zone architectures with a central server are known. Here, on the one hand, the server contains many powerful processors, and on the other hand, many software or applications run on the server. The communication effort in the control device is enormous, which represents a separate local area network. All of the vehicle's software will run here in the future, with each controller having its own software stack provided by different suppliers.

[0035] The concept of dynamically transferring functions and applications to other control units / processors, i.e. optimizing them, is known. This is called live migration, reallocation or migration. Serial applications for transferring software to other ECUs / processors are known.

[0036] Thanks to new architectures, hardware is becoming more generalized and software is becoming platform independent, so for the first time there is the possibility to implement software on different ECUs, which until now was not possible for all functions and ECUs. What software runs on which control unit (server) is therefore not necessarily determined at the time of designing the system. However, software migration is not limited here to ECU-to-ECU operations, but also applies to controller-to-controller operations within the same ECU. Summary of the Invention [Means for solving the problem]

[0037] The concept may be implemented in a standard-compliant manner without additional financial expenditures such as hardware costs. The use of the newly introduced Ethernet protocols in automobiles requires mechanisms that exploit certain characteristics of simple techniques and technologies to enable implementation without expensive implementations and further additional hardware. The network system according to the invention is improved in terms of reliability.

[0038] A particular application-specific benefit of more accurate and predictable delays is improved scheduling and execution of communications in vehicles. This means that existing bus systems can be used more efficiently and jumping on board expensive technology (higher bandwidth) can be avoided. This may also impact the required buffer storage, which may then be made unnecessary (or smaller). Fusion of different data (e.g. ultrasonic + radar, or microphone) may thereby be improved and made more accurate. Furthermore, data logging can be made much more accurate.

[0039] For software updates, more realistic time windows can be reported through the present invention and there is no need to assume the worst case, thus allowing downloads / updates that would otherwise never be initiated or be initiated later.

[0040] The use of the method according to the invention may also be used in other industrial fields using 10 Mbit / s Ethernet, such as for example industrial automation.

[0041] This object is advantageously solved by a method for optimizing a transmission data rate in a sensor network in a partial networking in an Ethernet network, the method comprising: a) the head node determining the number of active nodes; b) the head node classifying the identified nodes into two or more classifications of nodes for prioritizing Ethernet network communications; c) the head node receiving reservation requests from at least some of the plurality of nodes; d) in response to the reservation request, allocating time slots to one or more nodes in the upcoming communication window, the allocation being based on the priority of the nodes, which priorities are assigned to them according to their classification; after the number of active nodes is identified, a bus cycle length is calculated, the number of sleeping or inactive or defective nodes is identified, and a beacon bus cycle is identified in terms of how much the bus cycle length can be shortened.

[0042] In an advantageous embodiment of the method, the bus load is continuously monitored and the subsequent bus cycle is executed early by early transmission of a beacon (B').

[0043] A further advantageous embodiment of the method is characterized in that following the determination of the bus location (node ​​ID) of the sleeping node, a check is performed to determine whether there is a node with a higher bus location (node ​​ID) which does not represent an inactive sleeping node, and the bus location (node ​​ID) of the active node is optimized.

[0044] A further advantageous embodiment of the method further comprises determining the required download data rate in accordance with the last bus cycle (D frei ) is identified and the required data rate per bus cycle (D zus ) is identified, and the last bus cycle (D frei ) in the Ethernet network is compared to the required data rate per bus cycle (D zus ), no change is made in the next bus cycle and the last bus cycle (D frei ) is less than the required data rate per bus cycle, a change is made in the next bus cycle.

[0045] Particularly advantageous is an implementation by a control unit for an Ethernet network, designed as a first node to send signals to a second control unit of the Ethernet vehicle network, to receive signals from the second control unit, to determine a propagation time of the signal on a connection path to the second control unit, to determine a maximum speed of the connection path based on the propagation time, and to determine a type of transmission medium of the connection path based on the maximum speed, the control unit comprising at least a microprocessor, a volatile memory and a non-volatile memory, at least two communication interfaces and a synchronizable timer, the non-volatile memory containing program instructions which, when executed by the microprocessor, are capable of implementing and executing at least one embodiment of the method according to the invention.

[0046] Particularly advantageous is an implementation by an Ethernet network for a motor vehicle having a first control unit and a second control unit, the control units being connected to each other via at least one connection path, the first control unit being designed to execute the method according to the invention.

[0047] A particularly advantageous embodiment of the Ethernet in-vehicle network is characterized in that the Ethernet network has a third control unit that is only indirectly connected to the first control unit and directly connected to the second control unit via a third connection path, the third control unit being designed to determine a propagation time of a third signal on the third connection path, and the first control unit being designed to trigger the determination of the propagation time of the third signal via a service message to the third control unit.

[0048] By implementing the method disclosed by the present invention, it is possible to use platform-independent software with higher quality and durability. The present invention may also be used in other communication systems with clock synchronization components and embedded systems.

[0049] Exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail below. [Brief description of the drawings]

[0050] [Figure 1] 1 shows a schematic diagram of the difference between an Ethernet bus (10 Mbit / s) and a switched network. [Diagram 2] Illustrates the basic flow of communication on an Ethernet bus. [Diagram 3] 1 illustrates a physical representation of an Ethernet bus with a stub. [Figure 4] A sleeping node not only wastes a lot of bus bandwidth, but also increases the latency of other nodes unnecessarily. [Diagram 5] 1 illustrates dynamic adaptation of a transmission time window. [Figure 6] Solutions and advantages of shortening and adapting schedules or bus cycles individually are presented. [Figure 7] A further example of shortening an unnecessarily long schedule without the proposed optimization (top) and after optimization / shortening (bottom) is shown. [Figure 8] Calculation of the next beacon cycle with minimum and maximum values ​​is shown. [Figure 9] 1 shows the determination of beacon transmission time based on the location (here, node ID) of an active / asleep node. [Figure 10] 1 illustrates cycle time reduction and optimization by delayed transmission of the next beacon frame in the case of exclusively inactive participants (highest node IDs) at the "ends" of the bus. [Figure 11] An example of just one sleeping node (ID2) is used to illustrate various options for optimizing bus cycles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] Figure 1 shows a schematic diagram of the difference between an Ethernet bus (10 Mbit / s) and a switched network.

[0052] The present invention presents a novel method for optimizing the efficiency of data transmission on an automobile's 10 Mbit / s bus and reducing bus access times for nodes.

[0053] Figure 2 shows the basic flow of communication on an Ethernet bus: after the beacon is transmitted, it is node 0's turn first, and when it finishes its transmission, the next node is allowed to transmit (usually in each case only a single Ethernet frame may be transmitted in a slot).

[0054] The basic idea of ​​the method according to the invention describes a dynamic adaptation of the bus cycle. Unlike FlexRay, this has no negative or undesirable effects. The nodes do not have a fixedly defined time window, but only follow a sequence. The head node also does not know which data will be transmitted in advance by the nodes.

[0055] FIG. 3 shows a physical representation of an Ethernet bus with stubs.

[0056] The method first identifies all participants on the bus, which is usually statically pre-configured since the head node needs to know this number of participants to schedule flows.

[0057] Figure 4 shows that a sleeping node not only wastes a lot of bus bandwidth, but also unnecessarily increases the latency of other nodes.

[0058] Figure 5 shows the dynamic adaptation of the transmission time window. The head node then identifies all sleeping or faulty or inactive nodes on the bus. A distinction may be made here as to whether they are currently sleeping or whether the future time is known if the node is inactive, in which case sleeping or inactive means that they are not participating in bus communication (neither actively sending user data nor passively receiving user data). The head node receives this knowledge either through a higher software layer or application communicated by a message from one or the participants on the bus, for example a response to a sleep / wake-up signal due to an error condition of the node, for example through a request from the network administrator, checking the protocol, reading a register on the node.

[0059] Figure 6 shows the solution and the advantages of shortening and adapting the schedule or bus cycles individually. By transmitting the beacon frame, shown as "B", earlier, the subsequent cycle can always be executed earlier. The transmission slots of the individual nodes may be between 64 and 1522 bytes in size and are always shown as the same size, purely for simplicity.

[0060] FIG. 7 shows a further example of shortening an unnecessarily long schedule without the proposed optimization (top) and after optimization / shortening (bottom).

[0061] FIG. 8 shows the calculation of the next beacon cycle with minimum and maximum values.

[0062] The beacon cycle (i.e., when the next beacon will be transmitted, or the number of nodes active on the bus) may be calculated by identifying the number of sleeping or faulty or inactive participants. As such, one may first calculate how much time it is possible to save on the bus, or how much a bus cycle can be shortened, depending on the remaining number of active nodes, regardless of what ID they have.

[0063] Cycle length in normal mode: Z = participants x (send window + frame size) is therefore typically shortened to: Z' = (participants - inactive participants) x (send window + frame size)

[0064] FIG. 9 illustrates determining the beacon transmission time based on the location (here, node ID) of an active / asleep node.

[0065] Every node on the bus has a unique ID. The method uses the total number of nodes and their IDs to locate sleeping participants every bus cycle. The number of participants on an automotive 10 Mbit / s Ethernet bus is limited by the bus topology, so it is easy to get an overview of whether there are active nodes "behind" a sleeping or possibly failed node (IDsleepingnode <IDactivenode)。

[0066] If there are no further active nodes up to the highest ID, the beacon cycle is adapted such that a beacon is set before the transmission slot, so-called transmission opportunity, of the first sleeping node that only has active nodes in front and sleeping nodes behind. This method assumes that there are no further active nodes, or ECUs, sensors behind the sleeping node, i.e. higher ID, as shown in Fig. 10. This probability is relatively high, since 10 Mbit / s Ethernet bus systems in the automotive environment are nowadays usually designed for 8 ECUs.

[0067] FIG. 10 illustrates the reduction and optimization of cycle times by delayed transmission of the next beacon frame in the case of exclusively inactive participants at the "ends" of the bus, and therefore the highest node IDs.

[0068] However, if a node with a smaller ID no longer participates on the bus, the invention proposes to adapt or optimize the IDs of the participants.

[0069] In this regard, there are several proposals according to the present invention, as shown in Figure 11. The selection or combination of methods may be adapted depending on the application.

[0070] The IDs of all active participants on the bus with higher IDs are pre-decreased by the number of sleeping nodes. For example, if ID3 is asleep, then ID4 is decremented by 1. This maintains the transmission order of the bus participants.

[0071] Another possibility is to fill the sleeping IDs with the participants with the highest IDs. If ID3 is asleep, this ID is reassigned to the highest ID (e.g. ID8). This changes the order of the bus participants, but fewer bus participants need to be reconfigured.

[0072] FIG. 11 illustrates various options for optimizing bus cycles using an embodiment with only one sleeping node (ID2).

[0073] To avoid unnecessary optimization or adaptation of bus cycles, the method proposes to identify the current bus load, which may be identified by the time difference of the last beacon and the number of participating nodes. If the bus load is low, it may be statistically assumed that it will not increase sharply for the next cycle. However, it is proposed to continuously monitor the bus load, so that it is still possible to react to any changes.

[0074] In a final step, the bus cycles are adapted with respect to the required data rate. For this, two possibilities are proposed below.

[0075] In one advantageous sub-step, a method for comparing the required data rate with the current bus capacity may be identified. First, the required download data rate is calculated here for a 10 Mbit bus. Then, the number of active nodes is identified by the head node. The slots of inactive participants, either in an error state or in sleep mode, which are only passively listening, are identified, and the D frei The method is made available for a head node, referred to as

[0076] This already results in bus optimization, without the process of actively intervening in ongoing communication or muting nodes. The actual data rate may then be reported to the application, without the process of always assuming the worst case. This saves memory and returns a real-time window to the application, and possibly also to the driver. This method is a first step to optimizing cycles.

[0077] Another possible optimization step is described to prevent a subset (or even all) of the other participants on the bus (except the head node, of course) from transmitting based on the calculated required data rate at the head node, thus reducing the cycle time for download (or security update) purposes, so that the head node can provide its required data rate even if there is not enough bandwidth available according to normal bus operation. For this purpose, the amount of data that the head node still has to transmit in the current cycle is constantly compared, and this value is considered as a limit value that must not fall below 0 in this cycle, so that the cycle will end before by the transmission of the next beacon. This method results in the highest possible fairness towards the other bus participants, since only within a certain tolerance, as much bandwidth as is needed is used by the head node, and the remainder is still available for use by subsequent nodes. Since each bus participant can be between 0 (not transmitting any data), 64 (transmitting a minimum Ethernet frame) and 1522 bytes (transmitting a maximum Ethernet frame), the amount of nodes that may still transmit during a cycle due to this remaining bandwidth cannot be predicted exactly.

[0078] To further increase fairness, it is proposed that if a node is no longer able to transmit and the cycle ends by the next beacon (because the remaining required data rate in that slot is below the maximum potential Ethernet frame), the "remaining bandwidth" is carried over to the next cycle and released for use by other bus participants in the next cycle. In this way, a kind of "credit" can be accumulated even though the bandwidth requirements at the head node are met.

[0079] However, to prevent the credits from increasing excessively and thus potentially causing large data bursts during which many of the other bus participants could transmit large amounts of data unhindered, it is also proposed to limit the increase in credits in time, either by saturating or resetting the credits after a configurable period in seconds, or by a cycle counter, where the credits are saturating or resetting after a configurable number of bus cycles.

[0080] This kind of cycle optimization is not the only one that can be considered. An intermediate solution between "no fairness" and "maximum possible fairness" could be, for example, a simpler method in which only the head node is allowed to transmit for some cycles, with correspondingly large credits accumulating quickly. After a certain threshold, this could then be reduced once by inserting cycles in which all nodes are given the opportunity to transmit before they have to "rest" again for a certain number of cycles. If necessary, to simplify the method, this variant could be implemented without considering credits at all, just according to the number of cycles, for example "only the head node transmits 99 cycles, then all nodes transmit 1 cycle". However, in this case, certain jitters (variations) in the data rate of the head node cannot be eliminated.

[0081] The method according to the invention may also be carried out by alternative method steps in which, after determining the number of active nodes, unused transmission possibilities are determined, whereby an absolute data rate for the head node is calculated per time unit.

[0082] In the following, the invention proposes the method already presented to determine the trustworthiness of a communication partner or its application, provided that this trustworthiness is determined, an exchange of sensitive data may be performed.

[0083] A head node on a server, for example, is usually connected on a PCB (Printed Circuit Board) via MII (Media Independent Interface) or PCI Express, and may therefore always be managed without a transceiver (PHY).

[0084] Ethernet transceivers (PHYs) introduce delays in the triple nanosecond range, which sounds small, but delays on layer 2 (MAC) are in the single nanosecond range or tend towards zero, depending on how fine the measurement resolution is.

[0085] The method first identifies the address of the application between which data is to be exchanged (received, sent, or both).

[0086] The method then starts a propagation time measurement for this component. For example, the PDelay_Request method of the gPTP protocol (or 802.1AS) may be used here. In response, two responses may be sent back, using hardware timestamps to identify the propagation time of the message. (The use of protocols with hardware timestamps is important, so for example NTP is ruled out as its resolution is too imprecise).

[0087] Using this calculated value, the method calculates the physical distance to this participant, which is not expressed directly here in units of measurement, e.g., meters or centimeters, but may be converted into the number of components (PHYs, switches) that are part of the connection, since this delay is large in contrast to the delay on the actual cable.

[0088] Alternatively, the method measures the propagation time to a participant / address by initiating a propagation time measurement (eg, part of the PTP protocol) and calculating the distance from there to this participant.

[0089] The measured propagation times must first be evaluated to provide an indication of location. The software cannot know if the partner is located in the same ECU or not, ideally it must know if a generalized SW is used and not a special version, plus the IP address can be tampered with or changed. The propagation times of MII-based connections do not require a PHY (transceiver). However, neither the time synchronization software nor the actual application commissioning this study knows this. The PHY converts the data into electrical signals and encodes them, which takes much more time than if two Ethernet MACs communicated with each other over an MII-based line.

[0090] The presented method also recognizes if a participant is directly connected to the requesting participant. If not, then depending on the latency, a respective appropriate protocol may be selected. For example, MAC-Sec or IP-Sec may be used for latencies that apply inside the vehicle, and other IP / TCP based methods may be used if the latency is too high and the participant is undoubtedly outside the vehicle.

Claims

1. A method for optimizing a transmission data rate in a sensor network in partial networking in an Ethernet network conforming to IEEE P802.3cg (multidrop), comprising: a) the head node identifies the number of nodes, each of which has a unique node ID; b) the head node receiving reservation requests from at least some of the nodes; and c) in response to a reservation request, allocating time slots to one or more nodes in an upcoming communication window, said allocating being based on priorities of said nodes, said priorities being assigned thereto according to classifications of said nodes; After the number of active nodes and node IDs are identified by the head node, a bus cycle length (Z) is calculated, the bus cycle length (Z) being determined by the product of the number of nodes and the sum of a transmission window and a frame size, and the number of sleeping nodes, inactive nodes, or defective nodes and their respective node IDs are identified by the head node; A beacon cycle, which identifies when the next beacon will be transmitted and indicates the number of nodes active on the bus, is calculated by using the number of sleeping or inactive or defective nodes identified by the head node to identify the number of active nodes and to identify a shortened bus cycle length (Z'), which is determined by the product of the difference between the number of active nodes and the number of sleeping or inactive or defective nodes and the sum of the transmission window and the frame size; characterized in that the bus load is continuously monitored and subsequent bus cycles are executed early by early transmission of a beacon (B'), method.

2. 2. The method of claim 1, wherein following the determination of the node ID of the sleeping node, a check is performed to determine whether there is a node with a higher node ID that does not represent an inactive sleeping node.

3. A control unit for an Ethernet network conforming to IEEE P802.3cg (multidrop), comprising: - sending a signal to a second control unit of an Ethernet in-vehicle network and receiving said signal from said second control unit; determining a propagation time of said signal on a connection path to said second control unit; a control unit designed to determine a maximum speed of said connection path based on said propagation time, The control unit includes at least a microprocessor; a volatile and non-volatile memory; at least two communication interfaces, a synchronizable timer, The non-volatile memory, when executed by the microprocessor, Characterized in that it comprises program instructions capable of implementing and executing at least one embodiment of the method according to claim 1 or 2, Control unit.

4. 4. An Ethernet network for a motor vehicle having a first control unit and a second control unit, said control units being connected to each other via at least one connection path, said first control unit being designed like a control unit according to claim 3.

5. 5. The Ethernet network according to claim 4, characterized in that the Ethernet network has a third control unit (5) which is only indirectly connected to the first control unit (3) and directly connected to the second control unit via a third connection path, the third control unit being designed to determine a propagation time of a third signal on the third connection path, and the first control unit being designed to trigger the determination of the propagation time of the third signal via a service message to the third control unit.

6. A computer program comprising instructions which, when executed by a computer, cause the computer to carry out the method (200) according to claim 1 or 2.

7. A computer readable medium on which the computer program according to claim 6 is stored.

8. A vehicle having an Ethernet in-vehicle network comprising a plurality of control units according to claim 3.

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