Research On Traffic Scheduling And Performance Evaluation Of Avionics Networks

In recent years,the avionics system based on information technology has been developing towards the direction of integration,networking and modularization,which puts forward higher requirements on the timeliness,accuracy and safety of avionics airborne network.As a new real-time network technology based on time-triggered protocol,time-triggered Ethernet(TTE)is compatible with the standard Ethernet and AFDX airborne network,supporting multi-traffic mixed transmission,meeting the development needs of avionics system and is widely known as an ideal new-generation airborne networking technology.Considering the mission-critical and safety-critical characteristics of avionics systems,airborne networks pay more attention to the real-time performance of multi-traffic scheduling and networking.In this paper,the multi-traffic scheduling algorithm and real-time performance evaluation technology of TTE are intensively researched.The main works are as follows.To support the coexistence and scheduling of multi-traffic and reduce the queuing delay of RC services,we propose a two-phase multi-traffic hybrid scheduling algorithm(TMH).Based on the modeling and analysis of the scheduling problem,the TMH algorithm is designed with the idea of phased processing.In the first stage,In the first stage,the optimal transmission path is solved by using simulated annealing algorithm with load balancing and minimum routing hop as the optimization objectives.In the second stage,the multi-traffic alternate scheduling strategy is designed according to different traffic characteristics.Then,the correctness and effectiveness of TMH algorithm are verified by simulation model.Compared with the traditional partition scheduling method,the time domain resource utilization is improved and the RC average delay is reduced.In addition,under the star topology with redundant links,the algorithm can balance the load of the whole network,and the fluctuation range of load variance of each link is reduced by39.85% compared with the traditional path algorithm.To solve the problem of time-triggered(TT)traffic changing online in real network,we propose a two-phase multi-traffic dynamic hybrid scheduling algorithm(TMDH)with adjustable TT traffic proportion based on TMH algorithm.A counting and judging mechanism is designed for TT traffic in time domain,and then the first type(FTDSP)and the second type scheduling policy(STDSP)are implemented.The results show that:compared with the other two scheduling algorithms,TMDH algorithm not only meets the demand of fast online transmission of new TT traffic under a certain TT traffic proportion,but also guarantees the real-time performance of new TT traffic when the TT traffic is too much and exceeds the system’s capacity.In order to improve the pessimism of RC traffic delay evaluation results,we propose a TTOffset-NC performance evaluation method.Considering the TT traffic scheduling time bias,the upper bound of RC traffic delay is optimized by defining the reference frame and then using the relative bias of TT traffic to calculate the aggregate traffic arrival curve at the node port.The results show that: compared with other two evaluation methods,the pessimism of RC delay result of our method is reduced by nearly 20%,and the calculation compactness is reduced by about 36%,which is closer to the accurate delay.