GB2524170A

GB2524170A - Media oriented systems transport data communication network with radio communication for a motor vehicle and method for operating the same

Info

Publication number: GB2524170A
Application number: GB1502932.5A
Authority: GB
Inventors: Chamjiv Bangar; Andrew W Hill
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2015-02-23
Filing date: 2015-02-23
Publication date: 2015-09-16
Also published as: GB201502932D0

Abstract

A vehicle network based on Media Oriented Systems Transport (MOST) wherein first and second ring buses are connected via wireless bridging nodes (wireless adapters) in each respective ring bus. A Media Oriented Systems Transport data communication network for a motor vehicle, comprises a first ring bus 20A, a first set of multimedia units (AGW, HU, NAVI) connected to the first ring bus, and a first wireless adapter 10A connected to the first ring bus. It further comprises a second ring bus 20B, a second set of multimedia units (CDC) connected to the second ring bus, a second wireless adapter 10B connected to the second ring bus, in which the first wireless adapter and the second wireless adapter are coupled via a radio communication 30 (such as Ultra WideBand, UWB, Bluetooth (RTM) or Zigbee (RTM) to exchange data with each other. The first ring bus is closed by the first wireless adapter, which is designed to emulate the second set of multimedia units (CDC) by providing them as virtual bus members NICA1 to the first ring bus. A motor vehicle comprising such a data communication network as well as a method for operating such a data communication network is also presented.

Description

Intellectual Property Office Application No. GB1502932.5 RTN4 Date ti August 20t5 The following terms are registered trade marks and should be read as such wherever they occur in this document:

MOST

Bluetooth Virtex Wi-Fi Zigbee Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo Media Oriented Systems Transport data communication network with radio communication for a motor vehicle and method for operating the same The invention relates to a Media Oriented Systems Transport data communication network for a motor vehicle, which comprises a first ring bus, a first set of multimedia units connected to the first ring bus, a first wireless adapter connected to the first ring bus, a second bus, a second set of multimedia units connected to the second ring bus, a second wireless adapter connected to the second ring bus, in which the first wireless adapter and the second wireless adapter are coupled via a radio communication to exchange data with each other. The invention also relates to a motor vehicle comprising such a data communication network. The invention further relates to a method for operating a Media Oriented Systems Transport data communication network for a motor vehicle, which comprises a first ring bus connecting a first set of multimedia units and a first wireless adapter to the first ring bus, and a second ring bus connecting a second set of multimedia units and a second wireless adapter to the second ring bus, in which the first wireless adapter and the second wireless adapter are coupled via a radio communication, including the step of exchanging data with each other by the first and the second wireless adapter.

As the expectations for automotive teleniatics increase, so does the complexity of the system. This usually results in additional modules and additional cabling. Cabling between modules is a large problem in automotive not only due to cost and weight but also from a perspective of routing complexity. A channel must be found to route the cable, which will already contain other cables. Each cable may have different starting and finishing places, and each cable will have particular requirements regarding bend radius and installation clearance for the connectors.

This is an even larger problem for afterniarket or dealer installations as making modifications to existing harnesses means accepting the parameters already in play for that harness. Installation of new cables in the channels is often not possible due to incompatibilities of space, weight, bend radius, or cabling length. Even if it is physically possible to add cables, the amount of the interior fittings that must be removed can make the operation time prohibitive for the dealer.

Being able to adapt in-car communication to a wireless protocol therefore could realize significant savings in cabling, and allow easier future expansion.

Media-Oriented Systems Transport (MOST) is an interface used by many automobile manufacturers characterized by a synchronous data communication over a ring topology.

The MOST specification conforms to the OSI model of communication used in other networking protocols such as Ethernet. The current maintainer of the MOST specification, the MOST Cooperation, was founded in 1998.

MOST was designed specifically to transmit audio, video, data and control, effectively acting as a high-speed in-vehicle bus to standardize the interface and to minimize redundant cabling. In theory, it can run over either plastic optical fiber (POE) or over copper and can run between 50Mbps and 150Mbps. MOST is architected as a ring topology, where there are a number of time-synchronous channels allowing the transfer of isochronous data such as audio and video. Additionally, the standard was intended to be implemented by a variety of OEMs, allowing suppliers to use the same devices in multiple targets. In practice, however, the speeds of MOST were too slow for video, the adoption rate was poor and the POE transport cables were both expensive and difficult to route due to their fairly wide bend radius.

From US 7,917,109 B2 there is known a MOST network which includes a plurality of units that are arranged on a ring bus. A wireless transceiver interface is connected to the ring bus and receives input data from and transmits output data to a wireless device over a wireless communication channel. The wireless transceiver can be configured and arranged to provide output data in a format compatible with Bluetooth.

It is an object of the present invention to provide a MOST data communication network for a motor vehicle as well as a motor vehicle comprising the same and a method for operating such a data communication network which allows a more flexible arrangement of the multimedia units.

This object is solved by a data communication network having the features of patent claim 1, a motor vehicle having the features of patent claim 7 and a method having the features of patent claim 8. Advantageous embodiments with expedient and non-trivial developments of the invention are indicated in the other patent claims.

According to the present invention, a generic data communication network with the features of the preamble of patent claim 1 is enhanced in such a way that the first ring bus is closed by the first wireless adapter which is designed to emulate the second set of multimedia units by providing them as virtual bus members to the first ring bus. According to another aspect of the present invention, a generic method with the features of the preamble of patent claim 8 is enhanced by emulating the second set of multimedia units by providing them as virtual bus members to the first ring bus by the first wireless adapter, thereby closing the first ring bus. This offers to dramatically minimize wiring inside of the vehicle, needing only to feed the cabling to an antenna point rather than throughout the entire vehicle. The plastic optic fibre (POE) used for MOST is both expensive and has a poor minimum bend radius, which constrains physical placement of units inside the vehicle. It dramatically decreases the amount of cabling used in the vehicle, which represents a significant cut in the costs of wiring a module. It also gives much freer placement possibilities for modules inside the vehicle as the bend radius of the plastic optical fibre no longer constrains the module's location. UWB is also faster than MOST and so this protocol increases effective transmission speed in a heavily loaded system.

According to a preferred embodiment, the second ring bus is closed by the second wireless adapter, which is designed to emulate the first set of multimedia units, providing them as virtual bus members to the second ring bus. Thereby, on each ring bus either a physical device or its mirrored device as a virtual bus member is present.

In a preferred embodiment the first wireless adapter and the second wireless adapter are designed to perform the radio communication using ultra-wideband radio technology.

Ultra-wideband (UWB) is a wireless communication standard well suited for in-vehicle communication. It uses fairly low power, spread-spectrum emissions, which is favourable for power and thermal budgets of the devices and also increases the amount of data that can be transferred within the maximum emission regulations for a particular band. In addition, it is highly resistant to multipath propagation, a distinct advantage in a cluttered space like a vehicle's cabin where placement of seats, passengers and luggage are all subject to frequent change.

In a preferred embodiment the first ring bus and/or the second ring bus include plastic optical fibre within. The first ring bus as well as the second ring bus might be set up by any composition of plastic optical fibre interconnection sections or electrically wired interconnection sections made of copper or other conductive materials. This gives a maximum degree of freedom in placement and connecting the multimedia units.

According to a preferred embodiment, the first ring bus and the second ring bus are logically identical in view of the bus members, particularly in view of the order of the bus members within each ring bus. This is useful by creating the virtual bus members as mirrored clones of the real physical devices given by the two sets of multimedia units.

In a preferred embodiment there is virtual data provided by each virtual bus member, which contains a first binary information, which represents an attendance of the respective represented physical unit of the two sets of multimedia units, and a second binary information, which represents an inconsistency between the virtual bus member and the respective represented physical unit. This allows a fast response to a request from one bus member to another bus member, which is not physically present on the same ring bus.

According to another aspect of the present invention, a motor vehicle might comprise a data communication network as described before, thereby becoming an inventive motor vehicle.

Further advantages, features and details of the invention derive from the following description of a preferred embodiment as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone can be employed not only in the respective indicated combination but also in any combination or taken alone without leaving the scope of the invention.

The advantages described for the data communication network of the invention and features and embodiments thereof are equally applicable to the method according to the invention and vice versa. Thus, corresponding method features may be provided for features of the data communication network and vice versa.

The drawings show in: Fig. 1 a simplified schematic illustration of a wireless MOST adapter according to a preferred embodiment of the invention; and Fig. 2 a simplified schematic illustration of a MOST data communication network with two ring buses coupled via a radio communication according to a preferred embodiment of the invention.

In the following an experimental setup is presented. The use of the AGW,CDC, HU etc. are example telematics units that can be on the MOST bus. The CDC is not required to be the unit that is on the second ring, nor is it required that only one unit is on that second ring. Further, it is not necessary for the units to be telematics or multimedia units.

An original MOST ring 20 including a head unit HU and a compact disc changer CDC was targeted. The compact disc changer CDC was removed from the original MOST ring and replaced with a custom wMOST adapter 10, namely a first wMOST adapter 1 °A.

which gives a first MOST ring 20A Then, a new ring in form of a second MOST ring 20B was created with just the compact disc changer CDC and a wMOST adapter 10B In this way, a single ring of four devices was split into two rings one with a single device and the other with the remaining three.

The wMOST adapter 10 consisted of a Xilinx Virtex-4LX FPGA, a UWB transmitter 12 and a MOST Physical Layer and fiber optical transceiver (shown in Fig. 1 as an fiber optic receiver FOR/ fiber optic transmitter FOT pair), which is coupled to at least one MOST device 18 in a MOST ring 20. On the FPGA 11 was a MicroBlaze soft-core processor 15 and three MOST network interface controllers (N IC) / IP cores 16, which are internally coupled by a local MOST ring 21, as well as a UWB controller 17. The MicroBlaze ran software that handled the exchange of information between the UWB radio and the newly created MOST ring, namely the second MOST ring 2UB The first MOST ring 20A is coupled to the first wMOST adapter 1 °A by a first fiber optic receiver FORA and a first fiber optic transmitter FOTA. The second MOST ring 20B is coupled to the second wMOST adapter 1 °B by a second fiber optic receiver FORB and a second fiber optic transmitter FOTB. The first wMOST adapter 10A comprises a first UWB transceiver UWB XCVA and a FPGA-irnplemented first UWB controller UWBA as well as a first MicroBlaze soft-core processor MBA. The second wMOST adapter 1 OB comprises a second UWB transceiver UWBXCVB and a FPGA-implemented second UWB controller UWBB as well as a second MicroBlaze soft-core processor MBB.

As noted earlier, and as can be seen in Fig. 1, each wMOST adapter 10 contains multiple MOST IF cores 16. The purpose of this approach isto virtually duplicate the entire ring on both sides of the wireless interface. If we consider the original MOST ring 20 shown schematically in Fig. 2, we see (in clockwise order) the compact disc changer CDC, the navigation unit NAVI, the head unit HU and the audio gateway AGW. When we break this apart into two separate rings, namely a first MOST ring 20A and a second MOST ring 20B, joined by a wireless link 30, as shown in Fig. 2, we break it into two effectively identical rings by emulating the devices that are not physically present in the ring. So, in a first MOST ring 20A, the navigation unit NAVI, head unit HU and audio gateway AGW are physically present and the first wMOST adapter 1 QA contains a single MOST IF core NICA1 that represents the compact disc changer CDC. In the second MOST ring 2OB, there is the physical compact disc changer CDC plus a second wMOST adapter 1 OB containing three MOST IF cores 16, namely a second MOST network interface controller NICB2, a third MOST network interface controller NICBS and a fourth MOST network interface controller NICB4: one for each of the navigation unit NAVI, the head unit HU and the audio gateway AGW. With this method, each ring has an identical number of MOST controllers (whether distinct physical devices or FPGA IF cores) in the same order, and so can be used as logically identical rings.

Each physical device (audio gateway AGW, compact disc changer CDC, head unit HU and compact disc changer CDC) maps directly to an FPGA IF core (first MOST network interface controller NICA1, second MOST network interface controller NICB2, third MOST network interface controller NICBS and fourth MOST network interface controller NICB4) on the opposite ring, and the control settings must be identical. This includes the device ID and whether the device is a master or a slave on the ring. So in the first MOST ring 20A of our example, the bus master is the physical head unit HU, whereas in the second ring the master is the third MOST network interface controller NICB3 that is the virtual complement of the physical head unit HU.

In order to use them as logically identical rings, whenever a change is made to any of the MOST devices, whether a real device 18 or created with FPGA IF core 16, this change must be mirrored to all of the matching devices. So, if the real compact disc changer CDC on the second MOST ring 209 changes the currently playing track and sends a next track" message, this must be communicated to the FPGA IF core 16 representing the compact disc changer CDC on the first MOST ring, namely the first MOST network interface controller NICA1, which must also make a corresponding internal change and also send a "next track" message. This must happen on every instance, so if there were three or four rings involved, each of these rings' matching FFGA IF cores 16 would need to make these changes.

The MicroBlaze soft-core processor 15 is responsible for transferring the messages from the MOST FFGA IF cores 16 and sending them to the other ring over UWB. As these messages are received over UWB, the MicroBlaze on the receiving ring transfers these messages to the correct MOST NIC, which is responsible for transmitting them across the physical MOST ring.

While this works in the general case, MOST, like most network protocols, has a certain amount of error checking built into the protocol. However, as the protocol works on time-guaranteed delivery, both the latency and uncertainty added by the wireless link may be critical. For instance, one device, perhaps the head unit HU, may poll the compact disc changer CDC to see if it is present on the ring. As this request hits the dummy compact disc changer node on the first wMOST adapter 1 °A, this adapter will send back the message to the head unit HU that the device is on and ready to receive data. However, it is possible the compact disc changer CDC has not yet completed initialization, is not present in the system, or can otherwise not fulfill any requests made of it. It may seem to make sense to delay the responses from the compact disc changer CDC until the correct responses returns from the second MOST ring 20B as the true compact disc changer ring across the UWB wireless link 30, however the amount of time added by the wireless latency will often exceed the network timeout, and the head unit HU will not accept the message indicating a successful initialization.

Our solution is to add what is effectively a cache table to each of the MOST IF cores 16 on each ring 20A and 20B, containing a present bit (indicating the device the IF core represents is on and functioning correctly) and a inconsistency bit (indicating that the real device and its matching IF core could be in inconsistent states). When a real device attempts to send a message to the duplicated ring, first the transfer logic checks to see whether that device has indicated via UWB wireless link 30 that it is present and accessible. If it is not accessible, the MOST IF core ignores the message as if it never

S

received it, and does not send an acknowledgement back to the sender. This would be the effective action if all devices CDC, NAVI, HU and AGB were in the same physical ring but the receiver was not present and ready. As each real device comes online, it indicates its presence over the UWB wireless link 30 and each UWB wMOST adapter 10 updates its table accordingly. If a message arrives on a MOST IF core 16 that represents a device that has registered as present, namely one of the four MOST network interface controllers NICA1, NICB2, NICB3 and NICB4, that node forwards the message over LJWB wireless link to the appropriate ring to access the desired device and simultaneously indicates a successful transfer to the initiating node (in order to fulfill timing constraints). At the same time, it marks the inconsistency bit in its cache table to indicate that the results of the requested operation are not final. If the other node returns with an unsuccessful transfer, it notifies the original ring to cancel the original operation and indicate that it was in fact not successful. If the other node successfully completes the operation, the original ring is updated to clear its inconsistency bit.

As an example, imagine the compact disc changer CDC is currently playing the last track on the disc. A request from the head unit HU to advance the track ought to return a failure as there are no further tracks to play. However, the MOST IF core 16 representing the compact disc changer node on the first MOST ring 20A, namely the first MOST network interface controller NICA1 will return a success, mark the compact disc changer CDC as inconsistent and transmit the request to the second MOST ring 2OB When the second MOST ring 20B receives this request at the MOST IF core 16 representing the head unit node, namely third MOST network interface controller NICB3, this is passed along to the compact disc changer CDC who returns the message that it cannot fulfill the request. The MOST IF core representing the head unit node then transmits this back to the first MOST ring 20A, which cancels the operation, in this case by indicating that the previous track (in other words, the previously playing track) should be played (and is being played) instead.

Though this all happens in an amount of time to be too slow to fulfill MOST's timing requirements for a single request, practically it happens much too fast for the application processor to make the change, and in our experiments no glitches were apparent to the end user.

To minimize the number of erroneous transfers, more information about each node can be cached than simply whether the attached device is on and responding. Control information regarding the settings (i.e. number of tracks, current track, number of discs inserted, etc.) can be captured and cached as well. In this case, if a request for the next track occurs while the final track is currently playing, this is detected at the first MOST ring 20A so it can immediately refuse the request and does not need to send any synchronization message over UWB wireless link 30.

The embodiment merely serves to illustrate the invention without limiting it. Thus of course arrangements can feature any design, in particular as regards the number and arrangement of the bus members, without leaving the scope and spirit of the invention.

Also, the technical means for building up the wireless MOST adapter may vary as may the used wireless technology (WiFi, Zigbee etc.).

In conclusion, a data communication network and a method for wireless MOST bridging using ultra-wideband radio have been demonstrated.

List of reference signs wMOST adapter 1 OA first wMOST adapter 1 OB second wMOST adapter

11 field programmable gate array (ERGA)

12 UWB transmitter 13 fiber optic receiver (FOR) 14 fiber optic transmitter (FOT) MicroBlaze soft-core processor 16 MOST network interface controllers (NIC)/MOST P core 17 UWB controller 16 MOST device MOST ring 20A first MOST ring 20B second MOST ring original MOST ring 21 local MOST ring wireless link AGW audio gateway CDC compact disc changer FOR fiber optic receiver FORA first fiber optic receiver FORB second fiber optic receiver FOT fiber optic transmitter FOTA first fiber optic transmitter FOTB second fiber optic transmitter HU head unit MBA first MicroBlaze soft-core processor MBB second MicroBlaze soft-core processor NAVI navigation unit NICA1 first MOST network interface controller N1C32 second MOST network interface controller N1C83 third MOST network interface controller N1C84 fourth MOST network interface controller UWB_XCVA first UWB transceiver UWBXCVB second LJWB transceiver UWBA first UWB controller UWBB second UWB controller

Claims

Patent Claims A data communication network for a motor vehicle, comprising: -a first ring bus (20$ -a first set of bus units (AGW, HU,NAVI) connected to the first ring bus (20$, -a first wireless adapter (1 OA) connected to the first ring bus (204, -a second ring bus (203), -a second set of bus units (CDC) connected to the second ring bus (203), -a second wireless adapter (103) connected to the second ring bus (203), in which the first wireless adapter (10$ and the second wireless adapter (10) are coupled via a radio communication (30) to exchange data with each other, characterized in that the first ring bus (20$ is closed by the first wireless adapter (104, which is designed to emulate the second set of bus units (CDC) by providing them as virtual bus members (NICA1) to the first ring bus (20$.
2. The data communication network of claim 1, characterized in that the second ring bus (203) is closed by the second wireless adapter (1 OA), which is designed to emulate the first set of bus units (AGW, HU,NAVI) providing them as virtual bus members (N1C31, N1C32, N1C34) to the second ring bus (203).
3. The data communication network of claim 1 or 2, characterized in that the first wireless adapter (10$ and the second wireless adapter (20$ are designed to perform the radio communication using ultra-wideband radio technology.
4. The data communication network of one of the previous claims, characterized in that the first ring bus (20$ and/or the second ring (20$ bus includes plastic optical fiber within.
5. The data communication network of one of the previous claims, characterized in that the first ring bus (204 and the second ring bus (208) are logically identical in view of the bus members, particularly in view of the order of the bus members within each ring bus (20A 208).
6. The data communication network of one of the previous claims, characterized in that there is virtual data provided by each virtual bus member (NICA1, NICB1, NICB2, N1C84), which contains a first binary information, which represents an attendance of the respective represented physical unit of the two sets of multimedia units (CDC, AGW, HU,NAVI), and a second binary information, which represents an inconsistency between the virtual bus member and the respective represented physical unit.
7. A motor vehicle comprising the data communication network of one of the previous claims.
8. A method for operating data communication network for a motor vehicle, comprising a first ring bus (204 connecting a first set of bus units (AGW, HU,NAVI) and a first wireless adapter (104 to the first ring bus (204, and a second ring bus (20B) connecting a second set of bus units (CDC) and a second wireless adapter (108) to the second ring bus (208), in which the first wireless adapter (104 and the second wireless adapter (108) are coupled via a radio communication (30), including the step: -exchanging data with each other by the first and the second wireless adapter (iOA 108), characterized by -emulating the second set of bus units (CDC) by providing them as virtual bus members (NICA1) to the first ring bus (204 by the first wireless adapter (104 thereby closing the first ring bus (204.