Research On Performance Of Ethernet Technology For Next-generation Intra-Veichle Networks

Vehicles are being developed to be more and more intelligent,comfortable and safe to meet the growing demands for advanced functions.Devices related to driver assistant,online diagnosis and infotainment system are being integrated into the automobile electronic system.As a result,the bandwidth and the openness requirement of intra-vehicles network and the communication requirement between multiple subsystems are increasing.Today's intra-vehicle network,which integrates multiple heterogeneous sub-networks based on a central gateway,cannot meet the future demand of the automobile electronic system.The next generation intra-vehicle network will be evolved into a hierarchical architecture,where Ethernet acts as the backbone with heterogeneous subnetworks using different buses.Under such environment,how to make the Ethernet to provide the quality of service for automotive applications in intra-vehicle network,especially the guarantee for real-time,has drawn lots of attention from both academia and industry.The researches about Ethernet in intra-vehicle network are still in the prototype stage,and the schemes and protocols are still under discussion with no unified specifications.This thesis focuses on the two candidate Ethernet technologies which are Ethernet AVB and IEEE 802.1P/Q.The main work of this thesis is as follows:First,a detailed and easy method named FnLBF(First nRT Last class B Fragment),which aims at reducing the latency of real-time messages in Ethernet AVB has been proposed.This method aims at assisting the design process of intra-vehicle network.Based on the calculation of worst-case end-to-end delay,this method reduces the latency of real-time messages by adjusting the frame size of some message types.When ensuring the latencies are bellowing the required thresholds,this method could guarantee minimum changes of real-time stream and guarantee optimum frame size of non-real time messages to ensure the ratio of valid data in the non-real time stream.Second,under the background of intra-vehicle network,the thesis analyses the performance of some lightweight strategies for quality of service based on IEEE 802.1P/Q by building mathematical model.Based on a particular type of intra-vehicle Ethernet backbone network,the system model is built from the perspective of Queuing Theory,the average latencies of different types of messages are deduced and the performance of the discussed messages scheduling strategies are compared.Moreover,the time performance of real-time messages under the interference of non-real time message in discussed strategies has been evaluated.The work of this thesis has some reference significance for the improvement of Ethernet technology used in intra-vehicle network and for the design of intra-vehicle network.