1994-09-01

Robust Adaptive Data-Compression for Peak-Load Reduction in Low-Speed Automotive Multiplex Systems 941658

The improvement of low-speed MUX-systems in car-body areas gets important in a scenario where on one hand, the possible number of integrated local control units (LCU's) gets larger and on the other hand, the possible versions of a car range from basic to top-of-the-line. Cost and developement time can be reduced if the same MUX-System is used throughout this whole range. A possibility to realize this is the use of data-compression (DC) for data-transmission. Basic configurations integrating only a small number of LCU's of a car-MUX can communicate without using data-compression, whereas for the top-of-the-line versions, the performance can be enhanced using DC only for communication processes between additional control units causing critical peak load situations.
Specifically, the use of adaptive algorithms in automotive multiplex systems is a promising way to improve the MUX's capacity performance by minimizing redundant symbols/information in peak-load situations. The main problem in realizing adaptive compression is to get enough robustness in synchronizing the adaption of the compression base in both sender/encoder and receiver/decoder. Desynchronization appears mainly as a consequence of unrecognized transmission errors.
The algorithm is realized on a rapid prototyping platform on a 68000 computer using a standard LCU taskhandling operating system. This platform allows fast program developement as well as the real-time evaluation of different parametrizations of DC-algorithms and the integration into a simultaneous engineering process.
First results from laboratory-vehicle tests with a prototype of a traffic management control system on this platform are presented.

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