Role of in-car networking

An explanation of the needs, the development, and some of the choices in in-car networking starts with the windows. When automobiles were invented they were simply machines on wheels without windows. It was only later that windows were added, first at the front, then at the sides and back. The windows were static or insertable in one piece. This obviously was not very comfortable, neither for the handling of the windows, nor for the temperature regulation in the passenger cabin. Thus, in 1928 the first mechanical window winder, able to hold a window at any position desired, was presented to the public [1]. The first power windows were introduced in 1941 [2]. BMW was the first company to introduce power windows in Europe and the first BMW with all electric power windows was a “Serie 2 BMW 503,” which had an SOP at the end of 1957 [3]. This is where it gets interesting.

It is quite straightforward to imagine a switch in a vehicle door that actuates the electric motor for a window located in the same door. Everything is in one physical location and the wiring will be short. The wiring gets longer when all movable windows are required to be controllable by the driver, in addition to the “local” control in every door. More wiring between almost exactly the same locations is needed if a central door lock plus an electronic side mirror adjustment are also discretely wired. Figure 2.1(a) indicates that with only the basic comfort functions the size, weight, and number of wires will soon become prohibitive. In the case of discrete wiring, inventiveness quickly circles around the question of “How is it possible to fit another wire onto this inline connector or through this opening between e.g. body and door?” instead of fully exploring the possibilities of creating a new feature. On top of this, large wiring bundles are not only heavy, costly, and hard to install, but also error prone and difficult to diagnose [4].