In 1998, Mercedes Benz adopted the D2B (digital domestic data bus) car networking system architecture using POF  for its S-class series of automobiles. The D2B architecture consisted of a ring topology operating at 4–10 Mbit/s and was the first information entertainment networking system that united GPS navigation systems, audio, radio, and car phone. This networking system enabled

passengers to control each multimedia source through a central console panel.

 

With the success of the D2B system, the MOST Cooperation was founded in 1998 to standardize the multimedia networking technology and improve on the D2B architecture. Unlike D2B, the MOST standard was designed as a synchronous network system. A timing master sends the clock asynchronous and continuous data signals to all slave equipment, so that all the equipment is synchronized. This architecture avoids buffering and sample rate conversion.

 

The first mass-produced vehicle to use the MOST standard was the BMW 7 Series in 2001. After BMW’s adoption of MOST, Daimler, Audi, Porsche, Volvo, and Saab followed, with more than 115 vehicle models adopting the MOST standard today. And in 2012, Audi will continue the MOST tradition by implementing the MOST150 standard on its A3 model. The MOST150 standard again uses a ring topology to achieve its 150 Mbit/s transmission speed to improve the performance of each component used. The speed increase was enabled by enhancement of optical devices (transmitter and receiver) and improvements in LED drivers and network controllers.

 

Future POF requirements

There are several network protocols for a car network such as low-speed CAN (Controller Area Network), LIN (Local Interconnect Network), and high-speed CAN. Each protocol is classified as being part of the power train, body control, information control, or safety information.

 

Regarding safety, it has been common practice to prepare the communications network system separately from the body control system to ensure safety. So far, the bandwidth needed for adequate vehicle safety controls is 10 Mbit/s; however, new safety technologies such as advanced driver assistance systems (ADAS) are under consideration by car manufacturers and challenging the current MOST specifications.

 

The noise-free, weight-saving media features derived from POF networking systems, such as broadband capability, will prompt system engineers to improve the MOST requirements. Fortunately, the standards continue to evolve and already a 105ºC heat-resistant cable has been developed to supersede the former 85ºC cable. Apart from networking, POF can also be used for ambient lighting in a car, addressing both aesthetic functions like cup holders and mood lighting, as well as safety lighting concerns such as door and foot lighting.

 

Plastic optical fiber has been meeting the demands of the world’s premium car networking systems since 1998. Third-generation MOST150 standards are just now being implemented, but new POF designs are anticipated in order to address not only infotainment but also automotive lighting requirements for this 21st century and beyond.