Vehicle PHY configuration according to cable length

Abstract

An in-vehicle Ethernet network (20) for data communication within a vehicle (24) includes a plurality of cables (52, 56), a first Ethernet transceiver (60), and a second Ethernet transceiver (60). The plurality of cables include at least a first cable (56) having a first length and a second cable (52) having a second length shorter than the first length. The first Ethernet transceiver is coupled to the longer cable and configured to communicate first symbols over the longer cable at a first baud rate commensurate with the first cable length. The second Ethernet transceiver is coupled to the shorter cable and configured to communicate second symbols over the shorter cable at a second baud rate commensurate with the second cable length and lower than the first baud rate.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 467,003, filed on May 16, 2023, the disclosure of which is incorporated herein by reference.

[0002] The present disclosure generally relates to network communication, such as network communication in an automobile, and more particularly to methods and systems for setting the baud rate and other parameters of a physical layer (PHY) transceiver based on cable length.

[0003] Background Art Physical links connecting elements of a communication network are typically accessed using a physical layer (PHY) transceiver.

[0004] Aspects of PHY transceivers applicable to automotive Ethernet networks are described, for example, in IEEE Standard for Ethernet - Amendment 8: Physical Layer Specifications and Management Parameters for 2.5Gb / s, 5Gb / s, and 10Gb / s Automotive Electrical Ethernet.

[0005] The above description is presented as a general overview of related technologies in this field and should not be construed as admitting that any of the information it contains constitutes prior art to this patent application.

[0006] Summary of the Invention Embodiments described herein provide an in-vehicle Ethernet network for data communication within a vehicle, comprising a plurality of cables, a first Ethernet transceiver, and a second Ethernet transceiver. The plurality of cables include at least a first cable having a first length and a second cable having a second length shorter than the first length. The first Ethernet transceiver is coupled to the longer cable and configured to communicate a first symbol over the longer cable at a first baud rate commensurate with the first cable length. The second Ethernet transceiver is coupled to the shorter cable and configured to communicate a second symbol over the shorter cable at a second baud rate commensurate with the second cable length and lower than the first baud rate.

[0007] In some embodiments, a shorter cable provides one of the following links: (i) a link between a switch and a processor in the in-vehicle Ethernet network, (ii) a link between a switch and a storage device in the in-vehicle Ethernet network, and (iii) a link between a switch and a sensor device in the in-vehicle Ethernet network. In other embodiments, a longer cable provides a link between two switches in the in-vehicle Ethernet network. In yet another embodiment, a first Ethernet transceiver is configured to modulate a first symbol with a first number of bits for transmission over the first cable, and a second Ethernet transceiver is configured to modulate a second symbol with a second number of bits greater than the first number of bits for transmission over the second cable.

[0008] In one embodiment, each of the first and second Ethernet transceivers is configured to support both a first and a second baud rate, and is pre-configured to communicate at either the first or the second baud rate, respectively. In another embodiment, the first Ethernet transceiver is configured to support only the first baud rate, and the second Ethernet transceiver is configured to support only the second baud rate. In yet another embodiment, the first Ethernet transceiver has a first signal processing capability, and the second Ethernet transceiver has a second signal processing capability different from the first signal processing capability.

[0009] In some embodiments, the first Ethernet transceiver includes a first echo canceller having a first number of taps, and the second Ethernet transceiver includes a second echo canceller having a second number of taps less than the first number of taps. In other embodiments, the first Ethernet transceiver includes a first receiver including a first equalizer having a first number of taps, and the second Ethernet transceiver includes a second receiver including a second equalizer having a second number of taps less than the first number of taps. In yet another embodiment, the first Ethernet transceiver includes a plurality of echo cancellers operating in parallel requiring a first complexity level, and the second Ethernet transceiver includes non-parallel echo cancellers requiring a second complexity level lower than the first complexity level.

[0010] In one embodiment, the first Ethernet transceiver includes multiple equalizers operating in parallel, requiring a first complexity level, and the second Ethernet transceiver includes non-parallel equalizers requiring a second complexity level lower than the first complexity level. In another embodiment, the first and second cables are of the same cable type.

[0011] Embodiments described herein further provide a method for in-vehicle data communication in an in-vehicle Ethernet network comprising at least a first cable having a first length and a second cable having a second length shorter than the first length, wherein a first symbol is communicated over the longer cable by a first Ethernet transceiver coupled to the longer cable at a first baud rate commensurate with the length of the first cable. A second symbol is communicated over the shorter cable by a second Ethernet transceiver coupled to the shorter cable at a second baud rate commensurate with the length of the second cable and lower than the first baud rate.

[0012] This disclosure will be better understood from the following detailed description of its embodiments, in conjunction with the drawings. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic block diagram illustrating an automotive communication system according to embodiments described herein, in which a PHY transceiver can be configured according to the cable length. [Figure 2] Figures 2A-2D are block diagrams that schematically illustrate an example of a scheme for PHY connection in the communication system shown in Figure 1. [Figure 3] This flowchart schematically illustrates a method for configuring a PHY transceiver in an automotive network according to the embodiments described herein.

[0014] Modes for carrying out the invention Automotive Ethernet networks are useful for communication between end devices within a vehicle, such as between a central processor and various types of sensors. In vehicle networks, physical cables provide point-to-point communication links. Cables can include, for example, shielded or unshielded twisted-pair cables and coaxial cables.

[0015] Automotive communication networks can be configured in various topologies. For example, modern automotive networks may be configured in a "zone topology," in which several interconnected gateways are located in selected zones of the vehicle, and end devices are connected to the zone gateways. Gateways in a zone topology can include, for example, network switches such as Ethernet switches, network aggregators, local hubs, or processors.

[0016] In a zone topology, end devices in each zone are located near a common gateway and can therefore be connected to that gateway using relatively short cables, such as 2 to 5 meters in length. In contrast, gateways are located far apart from each other within the vehicle, so connecting gateways typically requires longer cables, such as 10 to 15 meters in length. In the following explanation, physical links within a zone will also be referred to as "zone links," and physical links connecting gateways will be referred to as "inter-zone links."

[0017] Physical links within a network may be accessed via physical layer (PHY) transceivers, which transmit and receive symbols modulating data bits over the physical links. The number of bits per symbol (denoted as Nb) is also referred to herein as the "modulation order."

[0018] The rate at which symbols are transmitted (or received) over a cable is called the "symbol rate" or "baud rate" (indicated as BR). The rate at which data bits are transferred over a cable is called the "data rate" (indicated as DR). The data rate is related to the baud rate, as given by DR = BR·Nb. This means that the same data rate can be achieved with different combinations of baud rate and modulation order. For example, in pulse amplitude modulation (PAM) PAM2 modulation scheme (Nb=1), the baud rate is equal to the data rate. By using PAM4 modulation scheme (Nb=2), the baud rate can be halved while maintaining the same data rate.

[0019] The amount of power consumed by a PHY transceiver typically increases with the baud rate at which the PHY operates. Therefore, communication using low baud rates can be advantageous in reducing power consumption. Low baud rates can also reduce the complexity of the PHY and improve its immunity to electromagnetic interference. In the disclosed embodiments, as will be discussed later, the PHY transceiver can be configured to communicate at a baud rate that depends on the cable length.

[0020] Signals traversing a physical link are attenuated according to the cable length. Specifically, with a given modulation scheme, cable attenuation increases as the cable length increases, resulting in a decrease in receiver performance. This allows for a higher modulation order when communicating over short cables than when communicating over long cables, without compromising reception performance.

[0021] Considering the above, a PHY transceiver may be configured with a high baud rate and low-order modulation scheme when communicating over long cables, or with a low baud rate (for example, to reduce power consumption while maintaining high noise immunity at high data rates) and high-order modulation scheme when communicating over short cables, resulting in reduced noise robustness but equivalent data rates and reception performance. This means that, in one embodiment, different PHY transceivers may be used for different cable lengths to optimize the size and cost of short-range PHY transceivers.

[0022] The PHYs in currently used automotive Ethernet networks are typically designed for a worst-case cable length of 15 meters. As a result, low-order modulation schemes and high baud rates are used for all cable lengths, leading to high power consumption due to the high baud rate. In a zone topology, zone physical links are much shorter than 15 meters (e.g., 2-5 meters), so it is possible to reduce the baud rate specified for 15 meters, at least for the zone physical links (e.g., to reduce power consumption while maintaining acceptable noise immunity).

[0023] In summary, in the disclosed embodiments, the PHY transceiver in the vehicle is configured to communicate at a baud rate that depends on the length of the cable to which the PHY is connected. Shorter cables allow for lower baud rates and reduced power consumption. Furthermore, for shorter physical links, the modulation order can be increased to compensate for the reduction in data rate due to uncompensated baud rate drops while maintaining receiver performance, even though higher modulation orders may make the device more susceptible to noise.

[0024] Consider an embodiment of an in-vehicle Ethernet network for data communication within a vehicle that includes a plurality of cables including at least a first cable having a first length and a second cable having a second length shorter than the first length, a first Ethernet transceiver, and a second Ethernet transceiver. The first Ethernet transceiver is coupled to the longer cable and is configured to communicate a first symbol via the longer cable at a first baud rate corresponding to the first cable length. The second Ethernet transceiver is coupled to the shorter cable and is configured to communicate a second symbol via the shorter cable at a second baud rate corresponding to the second cable length and lower than the first baud rate. By using a lower baud rate for communication via the shorter cable, power consumption can be significantly reduced.

[0025] In this context, the expression "baud rate corresponding to the cable length" means that the baud rate and the underlying modulation order are suitable for communication via the cable at the required data rate and acceptable receiver performance.

[0026] The first (longer) and second (shorter) cables within the in-vehicle Ethernet network can provide communication links between various elements within the in-vehicle network. For example, in an exemplary zone topology, the shorter cable provides one of (i) a link between a switch and a processor of the in-vehicle Ethernet network, (ii) a link between a switch and a storage device of the in-vehicle Ethernet network, and (iii) a link between a switch and a sensor device of the in-vehicle Ethernet network, and the longer cable provides a link between two switches of the in-vehicle Ethernet network.

[0027] The currently used standards related to Ethernet PHY transceivers are usually defined for cables much longer than automotive zone links. Therefore, the currently used PHY transceivers for zone links have unnecessarily large size, cost, and power consumption.

[0028] The reduction of the baud rate of a short cable usually results in a reduction of the data rate. In some embodiments, in order to compensate for the reduction of the data rate, a higher-order modulation scheme can be used via a shorter cable. For example, a first Ethernet transceiver is configured to modulate a first symbol for transmission via a first cable with a first number of bits, and a second Ethernet transceiver is configured to modulate a second symbol for transmission via a second cable with a second number of bits greater than the first number of bits. Generally, it should be noted that the higher the modulation order, the lower the tolerance to noise, but this reduction in robustness is offset by the shortening of the physical cable length.

[0029] In some embodiments, the Ethernet transceiver supports a flexible baud rate configuration. In such embodiments, each of the first and second Ethernet transceivers is configured to support both a first baud rate and a second baud rate, and is pre-configured to communicate at the first or second baud rate, respectively. In an alternative embodiment, the first Ethernet transceiver is configured to support only the first baud rate, and the second Ethernet transceiver is configured to support only the second baud rate.

[0030] The signal processing capability of an Ethernet PHY transceiver usually increases with the underlying baud rate. As a result, an Ethernet transceiver connected to a shorter cable may require lower signal processing capability, resulting in reduced power consumption and a smaller chip area.

[0031] Ethernet transceivers typically include an echo canceller to mitigate reflections of the transmitted signal and an equalizer to reduce intersymbol interference (ISI). Both the echo canceller and the equalizer are usually implemented using filters with multiple taps. Since the performance of echo cancellers and equalizers improves with lower baud rates, Ethernet transceivers communicating over shorter cables may benefit from using echo cancellers and / or equalizers with fewer taps.

[0032] In one embodiment, to accommodate a (high) first baud rate, the first Ethernet transceiver includes multiple parallel-operating echo cancellers requiring a first complexity level. In this embodiment, because the baud rate is lower, the second Ethernet transceiver includes non-parallel echo cancellers requiring a second complexity level lower than the first complexity level.

[0033] In one embodiment, to accommodate a (high) first baud rate, the first Ethernet transceiver comprises multiple parallel-operating equalizers requiring a first complexity level. In this embodiment, because the baud rate is lower, the second Ethernet transceiver comprises non-parallel equalizers requiring a second complexity level lower than the first complexity level.

[0034] The cables used in an in-vehicle Ethernet network may be of various types. In one embodiment, the first cable and the second cable are of the same type.

[0035] In the disclosed technology, Ethernet transceivers operate at a baud rate that depends on the cable length. For example, shorter cables can use lower baud rates compared to longer cables. Furthermore, for shorter cables, higher-order modulation schemes can be used to compensate for the decrease in data rate due to the lower baud rate. Communicating at low baud rates using a zone topology with short zone cables offers advantages in terms of reduced power consumption, reduced complexity, applicability to lower-quality and cheaper cables, and reduced chip area.

[0036] Figure 1 is a schematic block diagram showing an automotive communication system 20 in which PHY transceivers can be configured according to the embodiments described herein, depending on the cable length.

[0037] In one embodiment, the communication system 20 is installed in the vehicle 24 and provides in-vehicle connectivity between various devices, including a central processor, storage device 34, sensors and electronic control units (ECUs) 36, and cameras 40, such as an advanced driver-assistance system (ADAS) 28 and an in-vehicle infotainment (IVI) system 32. The ECUs can be used to control one or more sensors and to collect data from the sensors. The ADAS 28 can send control messages to the sensors and receive sensor data from the sensors via the vehicle network.

[0038] In various embodiments, the sensor 36 may include any suitable type of sensor. Some non-limiting examples of sensors include video cameras, speed sensors, accelerometers, sound sensors, infrared sensors, radar sensors, lidar sensors, ultrasonic sensors, ranging devices, or other proximity sensors.

[0039] Various devices communicating via the in-vehicle network may be clustered into separate zones, each corresponding to a device physically located near a common gateway within the vehicle, such as gateways 44A and 44B. In the example in Figure 1, a separate zone containing sensors 36 and cameras 40 is connected to gateway 44A around the front left, front right, rear left, and rear right corners of the vehicle. In another example, a zone associated with the central gateway 44B includes ADAS 28, IVI system 32, and storage device 34. The topology shown in Figure 1 is not mandatory, and other suitable zone topologies may be used in alternative embodiments. For example, in a different zone topology, different processors may be connected to different gateways and therefore belong to different zones.

[0040] The various elements of an in-vehicle network are connected to each other using cables of appropriate length, which are also referred to as "physical links" or simply "links" for brevity.

[0041] In the example shown in Figure 1, each gateway 44A connects to the sensors 36 and cameras 40 belonging to its zone via zone links 52. Similarly, gateway 44B connects to the ADAS 28, IVI 32, and storage device 34 in a separate zone via zone links 52. Gateway 44A is further connected to gateway 44B via inter-zone links 56. Gateways 44A and 44B may, for example, comprise Ethernet network switches. Alternatively, gateways may comprise network aggregators, local hubs, or processors. In the illustrated zone structure, for spatial zone clustering, the zone links 52 are much shorter than the inter-zone links 56.

[0042] Depending on the applicable Ethernet standard, links 52 and 56 may include any suitable physical medium. In the embodiments described herein, although not necessarily required, each link 52 and each link 56 includes a single pair of wires, for example, an optionally shielded single twisted-pair link. Alternatively, other types of links such as coaxial cables, bundled cables, or buses may also be used (but are not limited to these).

[0043] Each zone link 52 and each inter-zone link 56 is accessed using physical layer (PHY) transceivers 60 coupled at each physical link end. For clarity, Figure 1 shows only one pair of PHYs (60) used to access the zone link 52 between gateway 44A and camera 40.

[0044] The lower part of Figure 1 shows a detailed block diagram of PHY 60, which transmits data to peer PHY 62 and receives data from peer PHY via twisted-pair cable 64. In this example, cable 64 functions as a zone link 52. Alternatively, cable 64 could function as an inter-zone link 56 or any other cable in the automotive Ethernet network.

[0045] In the transmission direction, PHY 60 receives bits for transmission from a medium access control (MAC) device (not shown). Symbol mapper 70 maps the received group of bits (e.g., a group of Nb bits) to their respective symbols according to the underlying modulation scheme. Digital-to-analog converter (DAC) 72 modulates the group of bits to analog symbols at the required baud rate, and hybrid module 74 transmits the symbols to the peer PHY via cable 64.

[0046] In the receiving direction, PHY60 receives analog symbols transmitting bits from peer PHY62 via cable 64. Hybrid module 74 transfers the received symbols to analog-to-digital converter (ADC) 76, which outputs a digital signal. After applying echo rejection (described later), equalizer 78 filters the digital signal to reconstruct the symbols generated by peer PHY. Slicer 80 reconstructs the bits carried in the received symbols and sends the reconstructed bits to the MAC device.

[0047] PHY60 includes an echo canceller 82 for removing echo signals generated by reflections of the transmitted signal. Such reflections can be caused, for example, by faulty electrical connectors along the path to the peer PHY. The echo canceller receives a sampled signal of the transmitted signal and filters this sampled signal to generate a cancellation signal. A subtractor 84 subtracts the cancellation signal from the digital signal output by ADC76 to generate an echo suppression signal that is input to equalizer 78. Alternatively, the cancellation signal may be inverted (e.g., by -1) and added to the signal output by the ADC.

[0048] In the example in Figure 1, various elements of the PHY transceiver can be configured depending on the length of the physical link (e.g., cable 64) to which the PHY transceiver is connected. For this purpose, in some embodiments, the PHY transceiver 60 includes a parameter mapper 86 that handles various parameter settings within the PHY transceiver. The parameter mapper may hold predefined parameters such as the baud rate, modulation schemes of different modulation orders, and the number of taps used in the echo canceller 82 and equalizer 78. The PHY transceiver 60 receives or holds the length of cable 64 and selects the actual parameter settings according to the cable length.

[0049] In some embodiments, the symbol mapper 70 and slicer 80 support a number of predefined baud rates and modulation schemes, each having a different modulation order. The actual baud rate and the modulation scheme used are selected by the parameter mapper 86 depending on the cable length. For example, assuming two length categories, "short cable" and "long cable," the PHY transceiver is configured to use a high baud rate and low-order modulation scheme when cable 64 is a long cable, and a low baud rate and high-order modulation scheme when cable 64 is a short cable, in order to reduce power consumption.

[0050] In some embodiments, each of the equalizer 78 and echo canceller 82 is implemented using a digital filter with multiple taps. The actual number of taps used is determined by the parameter mapper 86 depending on the cable length.

[0051] In the example in Figure 1, the PHY transceiver 60 supports selectable baud rates and modulation schemes, although this is not mandatory. In alternative embodiments, a given PHY transceiver may support only one combination of baud rate and modulation scheme according to a given length of cable 64. In these embodiments, multiple different PHY transceivers, each having a different baud rate and modulation scheme configuration, may be used within the same automotive network.

[0052] Next, we will describe various configurations for connecting elements via zone links 52 and inter-zone links 56.

[0053] Figures 2A to 2D are block diagrams that schematically illustrate an example of a scheme for PHY connection in the communication system shown in Figure 1.

[0054] In Figure 2A, the gateway 44A connects to the sensor 36 via a zone link 52. On the gateway side, a PHY transceiver 60, labeled PHY1, connects the gateway to the zone link 52. On the sensor side, a peer PHY transceiver 60, labeled PHY2, connects the other end of the zone link to a microcontroller 88 that mediates between PHY2 and the sensor. In one embodiment, the microcontroller 88 functions as a medium access control (MAC) controller and is therefore also referred to herein as a MAC device, host, or system-on-a-chip (SoC). In some embodiments, the PHY circuitry and the circuitry that performs the MAC function (e.g., the microcontroller 88) are integrated into the same device.

[0055] In Figure 2B, gateway 44A is connected to camera 40 via zone link 52. On the gateway side, a PHY transceiver labeled PHY1 is connected between the gateway and zone link 52. On the camera side, a peer PHY transceiver labeled PHY2 connects zone link 52 to a bridge device 90 that mediates between PHY2 and the camera.

[0056] In Figure 2C, gateway 44B connects to a central processor, such as ADAS28 or IVI system 32, via zone link 52. On the gateway side, a PHY transceiver labeled PHY1 connects between the gateway and zone link 52. On the central processor side, a peer PHY transceiver labeled PHY2 connects to the associated processor.

[0057] In Figure 2D, the central gateway 44B is connected to gateway 44A via an interzone link 56. In this case, PHY transceivers PHY1 and PHY2 connect gateways 44A and 44B to the opposite ends of the interzone link.

[0058] In the examples in Figures 2A to 2D, cable lengths are classified into two length categories: "short cable length" for zone links and "long cable length" for inter-zone links. In these examples, the PHY connected to the long cable is configured with a high baud rate and low-order modulation scheme, while the PHY connected to the short cable is configured with a low baud rate and high-order modulation scheme.

[0059] A zone structure with relatively short zone links has several advantages, as will be described herein.

[0060] As mentioned above, using shorter cables allows for a reduction in baud rate (and an increase in modulation order), which significantly reduces power consumption. For example, in a 10-gigabit PHY, reducing the baud rate from 5.6 baud to 2.8 baud (changing the modulation scheme from PAM4 to PAM16) can result in a power consumption reduction of approximately 40%.

[0061] Reducing cable length and baud rate is also beneficial for echo cancellation, equalization, and mitigation of electromagnetic interference, as will be discussed later in this specification.

[0062] Regarding echo cancellation, shorter cables typically result in fewer reflections than longer cables. Assuming a fixed number of taps in the echo canceller, using a lower baud rate will allow the echo canceller to function better and improve the residual echo signal. Alternatively, shorter cable lengths and lower baud rates allow for a reduction in the number of taps in the echo canceller while maintaining acceptable echo cancellation performance. Reducing the number of taps in the echo canceller also reduces implementation complexity, power consumption, and chip area.

[0063] As mentioned above, the Equalizer 78 is typically implemented using a digital filter with multiple taps. Shorter cables experience less attenuation than longer cables, so shortening the cable length allows the use of an equalizer with fewer taps compared to longer cables. This also reduces implementation complexity, power consumption, and chip area.

[0064] Communication over Ethernet links such as links 52 and 56 is susceptible to electromagnetic interference (EMI) from various sources, which can corrupt electrical signals, such as signals carrying data over the Ethernet links (52 and 56), potentially leading to communication errors and system malfunctions. Electromagnetic compatibility (EMC) is the ability of a device to operate as intended in an environment without affecting the ability of other devices in the same environment to operate as intended.

[0065] In an automotive environment, EMI sources can be located inside or outside the vehicle. External EMI sources include, for example, radio towers, power lines, and airport radar. Internal EMI sources include, for example, the vehicle engine and other mechanical and electromechanical components, windshield wipers, mobile phones, and infotainment systems. Furthermore, in a full-duplex bidirectional link, mutual interference can occur between the two communication directions.

[0066] When the baud rate is lowered for short cables, both EMI and EMC are improved through various mechanisms, such as the following: Lowering the baud rate reduces the bandwidth, which in turn reduces exposure to EMI signals, especially high-frequency EMI signals, thus improving EMI. • As the baud rate decreases, undesirable energy emissions from the PHY transceiver are reduced at out-of-band frequencies. Using a lower baud rate improves the PHY transceiver's immunity to out-of-band EMI. For example, lowering the baud rate places a wider bandwidth of interfering radar pulses (a significant source of EMI) out of band, allowing them to be filtered out. • Improved EMC and EMI allow for the use of lower-quality or cheaper cables that are more susceptible to interference than high-quality cables, thereby reducing costs.

[0067] The echo canceller 82 and equalizer 78 may be configured to operate in parallel or non-parallel. In one embodiment, to accommodate high baud rates, a PHY transceiver connected to a long cable may have multiple echo cancellers operating in parallel, requiring a first (high) level of complexity as well as relatively high power consumption. In this embodiment, because the baud rate is lower, a PHY transceiver connected to a short cable may have non-parallel echo cancellers, which require a second (low) level of complexity (and typically lower power consumption) than the first level of complexity.

[0068] In another embodiment, to accommodate high baud rates, a PHY transceiver connected to a long cable includes multiple equalizers operating in parallel, which require a first (high) level of complexity. In this embodiment, because the baud rate is lower, a PHY transceiver connected to a short cable includes non-parallel equalizers that require a second (low) level of complexity, which is lower than the first level of complexity.

[0069] Parallel implementation (as described above) may be necessary because the maximum speed at which various operations, such as filtering, can be performed is limited by the underlying silicon manufacturing process. For example, digital filtering using a 28nm process is typically slower than the same digital filtering using a 5nm process. Therefore, depending on the underlying process, a PHY for high-baud rate applications may need to use multiple subsystems (e.g., filters) operating in parallel with each other, with these subsystems operating at lower rates.

[0070] Different elements and components of the communication system 20, such as the PHY device 60, may be implemented using dedicated hardware or firmware, for example, using hardwired or programmable logic in one or more application-specific integrated circuits (ASICs) and / or one or more field-programmable gate arrays (FPGAs). Additionally or alternatively, some functions of the components of the communication system 20, such as the functions of the PHY 60, may be implemented in software and / or using a combination of hardware and software elements. Elements not essential to understanding the disclosed technology have been omitted from the diagram for clarity.

[0071] In some embodiments, the parameter mapper 86 includes a programmable processor programmed with software to perform the functions described herein. The software may be downloaded, for example, in electronic form over a network to one of the processors, or alternatively or additionally, provided and / or stored in a non-temporary tangible medium such as magnetic, optical, or electronic memory.

[0072] Figure 3 is a schematic flowchart illustrating a method for configuring a PHY transceiver in an automotive network according to the embodiments described herein.

[0073] This method begins with a connection operation 150 in which a network technician (or any other qualified person) connects a configurable PHY transceiver (e.g., 60) to a cable when building an automotive network. The cable has a specific length depending on the distance between the connected elements and the harness design within the vehicle.

[0074] In parameter configuration operation 154, the network technician configures the PHY to the baud rate and modulation scheme according to the cable length. For example, suppose cables in an automotive network are categorized into several length categories. For example, in two categories, cables are classified as either "long cables" (e.g., inter-zone links) or "short cables" (zone links).

[0075] In one embodiment, a network technician determines the cable length (or length category) and configures the baud rate and modulation scheme accordingly. In one embodiment, the parameter mapper 86 of the PHY 60 maintains a predefined mapping that maps length categories to corresponding baud rates and modulation schemes of different modulation orders. The network technician provides the cable length category to the PHY transceiver, and the parameter mapper maps the length category to the associated baud rate and modulation scheme. Generally, the mapping maps longer cables to higher baud rates and lower modulation schemes, and shorter cables to lower baud rates and higher modulation schemes.

[0076] In hardware configuration operation 158, the network technician configures the number of taps in the echo canceller, equalizer, or both of the PHY transceiver according to the cable length. In one embodiment, a parameter mapper maintains a predefined number of taps in the echo canceller and / or equalizer for each length category. The network technician provides the length category to the PHY transceiver, and the parameter mapper maps the length category to the corresponding number of taps in the echo canceller and / or equalizer. Following operation 158, the method terminates.

[0077] Lowering the baud rate can also be useful for communication over cables that support a given low frequency range. For example, consider a cable certified for communication at a data rate of 1 gigabit per second (Gbps) and supporting a frequency range up to 600 megahertz. Such a cable is typically not suitable for communication at a data rate of 2.5 Gbps because the Nyquist sampling rate in this case is 704 megahertz, which is much higher than 600 megahertz. To communicate at a data rate of 2.5 Gbps over this cable, it is possible to lower the baud rate by, for example, 5 / 4 times and change the modulation scheme from PAM4 to PAM5. As a result, the Nyquist frequency drops to 704·(4 / 5) ≈ 560 megahertz, which is supported by a 1 Gbps cable. Note that in this example, the baud rate does not depend on the cable length.

[0078] The embodiments described above are given as examples, and other suitable embodiments may also be used. For example, in the embodiments described above, cable lengths are mainly classified into two length categories, e.g., long cables and short cables. In alternative embodiments, cables may be classified into three or more length categories, e.g., long cables, medium-length cables, and short cables.

[0079] The embodiments described above are examples only, and the present invention is not limited to those specifically shown and described above. Rather, the scope of the present invention includes both combinations and partial combinations of the various features described above, as well as variations and modifications thereof that would be conceivable to those skilled in the art by reading the foregoing description and that are not disclosed in the prior art. Documents incorporated by reference in this patent application should be considered integral parts of this application, except that, insofar as any term is defined in those incorporated documents in a manner that contradicts the definitions made expressly or implicitly herein, only the definitions herein should be considered.

Claims

1. An in-vehicle Ethernet network for data communication within a vehicle, A plurality of cables, each including at least a first cable having a first length and a second cable having a second length shorter than the first length, A first Ethernet transceiver, coupled to a longer cable than the aforementioned, and configured to communicate a first symbol over the longer cable at a first baud rate corresponding to the length of the first cable, A second Ethernet transceiver is coupled to a shorter cable than the one described above, is matched to the length of the second cable, and is configured to communicate a second symbol over the shorter cable at a second baud rate lower than the first baud rate. An in-vehicle Ethernet network equipped with this feature.

2. The in-vehicle Ethernet network according to claim 1, wherein a shorter cable provides one of the following: (i) a link between the switch and the processor of the in-vehicle Ethernet network; (ii) a link between the switch and the storage device of the in-vehicle Ethernet network; and (iii) a link between the switch and the sensor device of the in-vehicle Ethernet network.

3. The in-vehicle Ethernet network according to claim 1, wherein a longer cable provides a link between two switches of the in-vehicle Ethernet network.

4. An in-vehicle Ethernet network according to any one of claims 1 to 3, wherein the first Ethernet transceiver is configured to modulate the first symbol for transmission over the first cable with a first number of bits, and the second Ethernet transceiver is configured to modulate the second symbol for transmission over the second cable with a second number of bits greater than the first number of bits.

5. The automotive Ethernet network according to any one of claims 1 to 3, wherein each of the first and second Ethernet transceivers is configured to support both the first baud rate and the second baud rate, and is pre-configured to communicate at either the first or second baud rate, respectively.

6. The in-vehicle Ethernet network according to any one of claims 1 to 3, wherein the first Ethernet transceiver is configured to support only the first baud rate, and the second Ethernet transceiver is configured to support only the second baud rate.

7. The in-vehicle Ethernet network according to any one of claims 1 to 3, wherein the first Ethernet transceiver has a first signal processing capability, and the second Ethernet transceiver has a second signal processing capability different from the first signal processing capability.

8. The in-vehicle Ethernet network according to any one of claims 1 to 3, wherein the first Ethernet transceiver comprises a first echo canceller having a first number of taps, and the second Ethernet transceiver comprises a second echo canceller having a second number of taps less than the first number of taps.

9. An in-vehicle Ethernet network according to any one of claims 1 to 3, wherein the first Ethernet transceiver comprises a first receiver having a first equalizer having a first number of taps, and the second Ethernet transceiver comprises a second receiver having a second equalizer having a second number of taps less than the first number of taps.

10. An in-vehicle Ethernet network according to any one of claims 1 to 3, wherein the first Ethernet transceiver comprises a plurality of parallel-operating echo cancellers requiring a first level of complexity, and the second Ethernet transceiver comprises a non-parallel echo canceller requiring a second level of complexity lower than the first level of complexity.

11. An in-vehicle Ethernet network according to any one of claims 1 to 3, wherein the first Ethernet transceiver comprises a plurality of parallel-operating equalizers requiring a first level of complexity, and the second Ethernet transceiver comprises a non-parallel equalizer requiring a second level of complexity lower than the first level of complexity.

12. The in-vehicle Ethernet network according to any one of claims 1 to 3, wherein the first cable and the second cable are of the same cable type.

13. A method for data communication within a vehicle, In an in-vehicle Ethernet network comprising at least a first cable having a first length and a second cable having a second length shorter than the first length, The steps include: communicating a first symbol via a longer cable, using a first Ethernet transceiver coupled to the longer cable, at a first baud rate corresponding to the length of the first cable; The steps include: communicating a second symbol via a shorter cable, using a second Ethernet transceiver coupled to the shorter cable, at a second baud rate lower than the first baud rate corresponding to the length of the second cable; and A method for data communication, including...

14. The method for data communication according to claim 13, wherein a shorter cable provides one of the following: (i) a link between the switch and the processor of the in-vehicle Ethernet network; (ii) a link between the switch and the storage device of the in-vehicle Ethernet network; and (iii) a link between the switch and the sensor device of the in-vehicle Ethernet network.

15. The method for data communication according to claim 13, wherein a longer cable provides a link between two switches of the in-vehicle Ethernet network.

16. A method for data communication according to any one of claims 13 to 15, wherein the step of communicating the first symbol by the first Ethernet transceiver includes the step of modulating the first symbol with a first number of bits for transmission over the first cable, and the step of communicating the second symbol by the second Ethernet transceiver includes the step of modulating the second symbol with a second number of bits greater than the first number of bits for transmission over the second cable.

17. A method for data communication according to any one of claims 13 to 15, comprising the steps of: supporting both the first baud rate and the second baud rate by each of the first and second Ethernet transceivers; and pre-configuring each of the first and second Ethernet transceivers to communicate at the first or second baud rate, respectively.

18. A method for data communication according to any one of claims 13 to 15, comprising the steps of: supporting only the first baud rate with the first Ethernet transceiver; and supporting only the second baud rate with the second Ethernet transceiver.

19. A method for data communication according to any one of claims 13 to 15, wherein the first Ethernet transceiver has a first signal processing capability, and the second Ethernet transceiver has a second signal processing capability different from the first signal processing capability.

20. A method for data communication according to any one of claims 13 to 15, wherein the first Ethernet transceiver comprises a first echo canceller having a first number of taps, and the second Ethernet transceiver comprises a second echo canceller having a second number of taps less than the first number of taps.

21. A method for data communication according to any one of claims 13 to 15, wherein the first Ethernet transceiver comprises a first receiver having a first equalizer having a first number of taps, and the second Ethernet transceiver comprises a second receiver having a second equalizer having a second number of taps less than the first number of taps.

22. A method for data communication according to any one of claims 13 to 15, wherein the first Ethernet transceiver comprises a plurality of parallel-operating echo cancellers requiring a first level of complexity, and the second Ethernet transceiver comprises a non-parallel echo canceller requiring a second level of complexity lower than the first level of complexity.

23. A method for data communication according to any one of claims 13 to 15, wherein the first Ethernet transceiver comprises a plurality of parallel-operating equalizers requiring a first level of complexity, and the second Ethernet transceiver comprises a non-parallel equalizer requiring a second level of complexity lower than the first level of complexity.

24. The method for data communication according to any one of claims 13 to 15, wherein the first cable and the second cable are of the same cable type.

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