Auto Electronics

Ten years of multimedia networking with MOST

Since its inception in ‘98, Media-Oriented Systems Transport (MOST) technology has made significant strides in the last 10 years. During that period, it has been accepted as the de-facto standard for multimedia and infotainment networking in the automotive industry. And it is being implemented in 55 car models worldwide, including the first Asian models from Toyota and Hyundai/Kia. A faster third-generation (150 Mbps) version has also been unwrapped, optimized for robustness, quality and efficiency.

About 10 years ago, BMW and Daimler with Harman (today Harman/Becker) and OASIS SiliconSystems (now SMSC) cooperated on defining and designing the MOST technology. Envisioning the future, the companies saw the need for a common infotainment network standard instead of proprietary solutions. In 1998, these companies founded the MOST Cooperation with Audi joining shortly thereafter. The first specifications were crafted with the ability to handle 25 Mbps. Within three years, BMW introduced the 7 series as the first MOST car in 2001. The following year 13 more models implemented the MOST infotainment backbone. Now, 10 years later, 16 carmakers and their 78 premier component suppliers contribute to the proliferation of MOST.

According to SMSC's senior director of business development Henry Muyshondt, “MOST Cooperation or MOSTCO is working with the consumer electronics industry to make it easier to connect CE devices to cars. Efforts are under way with the Consumer Electronics Association (CEA) to bring the CE and automotive worlds together. Many OEM suppliers are also working on this front with their aftermarket divisions that can benefit from using MOST.”

In cooperation with SMSC, semiconductor supplier STMicroelectronics has designed and launched the industry's first integrated power-management solution for MOST. The power management IC, designed to work with SMSC's MOST network processors, includes the power supply and MOST-compliant power-management control logic, with enhanced diagnostic and full system monitoring (power supply, network status, wake-up events, temperature).

Starting with 25 Mbps, the third-generation MOST has migrated to 150 Mbps data rate. The MOST rev. 3.0 specifications have just been released. Crafted to work with the MOST150 physical layer, it enables the use of higher bandwidth of 150 Mbps, an isochronous transport mechanism to support extensive video applications, as well as an Ethernet channel for efficient transport of IP-based packet data.

Backward compatible, the new generation of MOST provides the automotive-ready physical layer for Ethernet. The rev. 3.0 also adds significant enhancements to the control channel (which is used for real-time control of devices).

The rev. 3.0 incorporates several “lessons learned” from the experience of MOST Cooperation's compliance verification program. Emphasis has been put on clear specification points where conformance can be verified during compliance testing, according to MOST Cooperation.

The organization has taken measures to simplify risk assessment and increase confidence in the readiness to apply the new technology. For instance, diagnosis capability has been optimized by an overhaul of ring break diagnosis behavior as well as detection of sudden signal-off. The robustness of the procedures has been verified during the early phase of the specification by using failure-mode effects analysis (FMEA) as well as reference implementations through virtual prototypes. To verify ring break diagnosis behavior the functional and timing behavior was modeled and executed in more than 100,000 test sets that use well-known methods from system-on-chip (SoC)-verification. Additionally, digital transmission content protection (DTCP) has been adapted to the MOST standard. MOST was the first network to be fully approved by the DVD Copy Control Association (DVD CCA) to carry DTCP-protected content.

Offering backward compatibility, existing applications can be reused in the new network by modifying their network interfaces. Since rev. 3.0 supports the MOST150 physical layer, it allows carmakers to continue to use plastic optical fibers and LED light sources. Thus, allowing them to continue using their optical wire harness and assembly processes, making the transition to higher bandwidth networking a smooth evolution, said MOST Cooperation.

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