MOST 150 Star topology interconnects driver assistant systems

November 14, 2013 // By Christoph Hammerschmidt
Doing away with the limitation to the infotainment domain, the MOST standardising body MOSTCO has introduced an Advanced Driver Assistance System that concatenates high-definition video streams of up to eight cameras, offering a total bandwidth of 1.2 Gbit/s. The Based on the current MOST150 technology, the system links the surround view cameras to a central data hub through coax cable.

This approach of a MOST-based multi-channel network with inherent synchronicity suits very well to the needs of driver assistance systems since it guarantees strict real-time determinism and an ultra-low latency of 10 milliseconds, flexible topologies, high bandwidth, safety and robustness. In addition, the technology can be considered as mature.

This automotive 360° top-view system utilizes cameras with a high dynamic range at low space requirements. Implemented as a remotely controlled two-chip solution, the cameras do not require a microcontroller.

A multiport network interface controller in the central unit allocates the full real bandwidth to each path. Each path can be configured in any conceivable topology such as ring, star, tree or bus. The branches can be connected or separated during full operation without impacting the data stream in the main system, says MOSTCO.

The video data stream between camera and processing unit represents a significant amount of data. In particular in ADAS applications, this continuous data flow must not be interrupted at any time. Not even a delay can be tolerated. The MOST architecture ensures this data transfer at guaranteed bandwidth and latency times - a clear differentiator against multiplexed architectures. No further communications processors or address data are required. Likewise, there is no need of packetizing the data, and thus no bandwidth is wasted by packet inspection for the address data processing and packet routing.

The coaxial wiring offers a scalable PHY for the driver assistance domain within the car since it ensures bidirectional data exchange and power supply across one cable. Coax wiring is the industry standard for RF signals. These cables are inherently shielded, and cost-effective cables and connectors are readily available. Critics however say that coax is more costly than the twisted-pair wiring used for the competing Ethernet technology, and, even more importance, twisted pair has a lower bending radius, a factor that is critical for wiring systems in car bodies.

Despite these arguments, MOSTCO claims