Infotainment technology on the move

  • 21-Nov-2011 07:53 EST
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The adoption of MOST150 is driven by the permanent increase of bandwidth requirements. As shown in the image, only a limited number of network layers are affected by the change in technology.

Audi and Daimler announced that they will introduce MOST150 networks in future vehicles. At the VDI (Association of German Engineers) congress on Electronic Systems for Motor Vehicles, the two vehicle manufacturers gave some insight into their activities to validate future infotainment network technology.

“We will introduce the first vehicle with a MOST150 based infotainment network in 2012,” said Dipl. Ing. (FH) Stephan Esch, head of E/E vehicle networks at Audi. According to the networking specialist, the new Audi A3 will use MOST150 to network infotainment components and functions.

This global industry-first application, however, is only the beginning said Esch: “Following the initial application in an Audi model, MOST150 will be used for future series applications. The roll out of this new type of all-over-one-wire infotainment will continue in further Audi models and the VW A-segment.” Daimler will first introduce the MOST150 standard in its on-coming S-Class, which is scheduled for 2013, according to Dipl. Ing. Stefan Wachter, manager for telematics system networking within Mercedes-Benz cars development.

Both premium vehicle manufacturers collaborated within their MOST Cooperation membership to validate the new MOST multichannel network standard. Audi performed the initial tests based on an evaluation board with seven devices to confirm use cases and basic functions such as timing, power management parameters, communication channels, and wakeup/sleep.

Daimler picked up from this and implemented the INIC firmware, MOST Netservices, and the INIC host CPU interfaces in a generic controller to check all relevant parts of the network stack. Then Audi installed the network components in a car to verify the system’s sensitivity to physical stress. This included temperature stress, high and low voltages, sleep/wakeup, and bus diagnosis. The final step of evaluation was handled by Daimler again. It consisted of bringing in Tier 1 suppliers to see if the standard can actually be integrated into their devices.

Confirmed use of the MOST Ethernet channel

"We achieved system stability. The performance of the new standard was optimized during our joint validation of MOST 150 and the relevant hardware components, such as the photo-optic transmitter, have been qualified to automotive standards. Now that we found that MOST150 is a stable standard, we can focus on function development”, Wachter concluded in Baden-Baden. “During the validation process we also confirmed the use of the new standard’s Ethernet channel with over 100 Mbit of bandwidth”, Stephan Esch added.

The Audi manager stressed that it simply makes sense “to have one interface for all data. Take the networking of consumer electronics devices via the new isochronous channel which is perfect for video streaming.” The new Ethernet channel (Ethernet interface according to IEEE 802.3), which is part of MOST150, will serve to establish a link structure suited for devices with IP address. Therefore Esch considers the new MOST specification “The solution for infotainment networks.”

The physical component layer of the bus can remain more or less the same. The connectors, for instance, and the POF (polymer optical fiber) cable do not require any changes. Yet, the new MOST specification also supports coaxial cable as physical layer. In other areas the new standard offers improvements which go back to lessons learnt from MOST25. “Among the new functions are improved network diagnosis features such as the detection of dynamic events”, Wachter explained. “Sudden signal-off situations can now be detected so that the detail level of error analysis is much better.”

In a brief outlook, Wachter said that MOST150 offers further potential “for connecting other image and sensor based systems which pose similar streaming and latency requirements as infotainment systems do.” Esch added that “the evaluation of other use cases including driver assistance functions is ongoing.”

Asked about the expected development of the Ethernet standard in automotive applications, Esch assumed a rather neutral, matter-of fact attitude: “IP will definitely grow, and it is important to distinguish between IP protocol and the lower layers (data link and physical layer). MOST150 is an existing solution for automotive IP applications and Ethernet might be another one in future. It all depends on the system requirements as this is the real basis for choosing the best infotainment standard.”

BMW uses Ethernet with unshielded twisted pair cable

BMW confirmed during the VDI conference that it is readying Ethernet with unshielded twisted pair (UTP) cable for automotive applications. Said Albrecht Neff, Project Manager Ethernet, within the company’s electronic development: “Networking via Ethernet and IP over unshielded twisted pair cable is ready for series application. We have given a definite 'go.'”

BMW has been cooperating with Broadcom and Freescale to get to this point. According to the BMW expert, adapting the industrial Ethernet standard (IEEE 802.3) to automotive requirements mainly necessitated changes on the physical level. “The automotive qualification was completed by BMW in 2010”, said Neff. The first application is networking a camera-based park pilot, which is scheduled for market introduction in 2013.

As the shielding of Ethernet cable is expensive, a lot of effort went into ensuring electromagnetic compatibility with UTP cable. “This is not a trivial matter,” Neff explained.

The vehicle manufacturer now seeks to establish Broadcom technology as an open standard and pursues this goal within a special interest group. Among the benefits of Ethernet, which are owed to the 100 Mbit full duplex bandwidth, Neff mentioned that flash times are drastically reduced: “While it can take up to 16 hours to flash vehicle systems via CAN, the same procedure takes 30 minutes via Ethernet.”

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