Multi-Layered In-Vehicle Communication Architectures

Abstract

Modern bus platforms contain an increasing number of electronic control units (ECUs) distributed over long physical distances. This creates challenges for the in-vehicle communication architecture, since long cable routes, increasing traffic demands, and stricter timing requirements may reduce communication robustness and increase end-to-end delay. Controller Area Network (CAN) is widely used in vehicle systems due to its robustness, simplicity, and established industrial use. However, in long vehicle platforms, CAN-based communication may approach practical limitations related to cable length, signal integrity, and transmission delay. This thesis investigates how a multi-layered in-vehicle communication architecture can be modeled and optimized by combining different communication technologies in a common bus architecture. The considered technologies include CAN, Ethernet, and AUTBUS. The objective is to determine where different technologies should be used and where converters should be placed in order to balance total system cost and communication delay. A mixed-integer linear optimization model is developed to assign communication technologies to discretized bus segments and to determine the required gateway placements. The model includes cable costs, gateway costs, gateway delays, transmission delays, propagation delays, ECU interface constraints, and a maximum consecutive CAN length constraint. Since cost and delay are conflicting objectives, an epsilon-constraint method is used to generate Pareto-optimal architecture alternatives. A secondary fine-tuning model is also introduced to refine boundary positions after the discrete topology has been selected. In addition to the mathematical model, physical gateway latency measurements are performed using a CANcase, CANalyzer, and CAPL scripts. The measurements show that gateway latency is not constant, but varies depending on transmission interval and network traffic. The measured latency is therefore used as a representative modelling parameter rather than an exact deterministic value. The results show that optimization framework can identify meaningful trade-offs between cost and delay in a long bus communication architecture. The Pareto front provides several feasible design alternatives, ranging from low-cost solutions with higher delay to more expensive architectures with lower delay. The fine-tuning step further reduces cost for selected Pareto points, especially in the higher-cost region of the frontier. Overall, the thesis demonstrates that mixed-technology communication architectures can provide a structured approach for improving timing performance in long vehicle platforms, provided that gateway behavior, protocol constraints, and implementation complexity are carefully considered.