Design Of Aircraft AFDX Network Delay Calculation System Based On Network Calculus

With the development of Avionics systems, interactions between systems became more and more complicated, the transmission data flow becomes huge. Classic Arinc 429 data bus cannot fulfill the requirement of Avionics systems. Avionics Full Duplex Switched Ethernet(AFDX) has emerged and been adopted in many aircraft types in recent years. Network topology and routing transmission makes it complicated to calculate the delay of AFDX network, and the accuracy is quite low.The author studied the network calculus and the structure of AFDX network firstly, and then designed the AFDX network delay calculation system. Taking advantages of network calculus, the author built models for the components of AFDX network elements and did the test work to make sure the result of calculation system was acceptable and reasonable. This thesis has finished the following researching tasks.1. AFDX network delay is analyzed in the following chapters. Total delay is divided into four parts: delay of sending end system, delay of sending network switch, delay of receiving network switch and delay of receiving end system. For each part, it contains receiving delay,modeling delay, route delay and queuing delay, in which queuing delay contributes most. The calculation refers to base theory of network calculus, and different priority types are considered.2. Calculation of AFDX delay is performed. Models are built for three base elements of AFDX network, namely End System, Network Switch and Virtual Link. The delays of virtual links are calculated separately according to their priorities, using formulas based on network calculation.3. AFDX network delay calculation system is implemented. To test the delay calculation,three different AFDX network data load scenarios are used. The result of delay calculation is validated by comparing the delay of different scenarios and different priorities.Based on characteristics of AFDX network delay, the main result of the study is to design AFDX network delay calculation system. From the calculation system, delays of different parts of AFDX network can be worked out, with consideration of different priorities.With the help of delay calculation system, it is easy to find out whether the network can meet the real-time requirement of end system. The outcome of the study gives a good reference for those who are using AFDX network for data communication in Avionics system.