Congestion Detection And Avoidance Strategy For Hierarchical Services In Space-Ground Integrated Networks

The high coverage of satellites in space-based networks can solve the problem that ground-based networks are difficult to extend to some extreme environments and become an effective supplement to groundbased networks,and the current research related to the integrated network between heaven and earth has become a key project in the national 13th Five-Year Plan.However,at the same time,the communication environment of space-based networks is complex.In this paper,we propose solutions to the congestion problem in the DTN network architecture based on the integrated network between heaven and earth from two perspectives of congestion detection and congestion avoidance.DTN networks are characterized by long time delay and frequent connection interruptions.Data in the network is transmitted through contacts,which have start and end times,and the amount of data that can be transmitted during the connected period of the contact is limited.Routing in DTN networks is composed of sequences of contacts,and when the available capacity of a contact on a route is exhausted due to congestion,the route is no longer available.This may lead to the failure of the routing used by the lower priority data units.The first innovation of this paper is the CGR-Key algorithm based on the load evaluation of key contacts,which defines the contacts with higher risk of congestion as key contacts,proposes the calculation method of key contacts,and detects the congestion problem in the network in time by monitoring the change of available capacity of key contacts on the route based on the setting of threshold value.According to the simulation experiment results,the delivery rate of requests is improved.Load imbalance also exists in DTN networks,where routes from different destination nodes in the routing table may share the same waiting queue to forward data,and bundled packets need to compete for the capacity of the waiting queue.Due to the difference in performance of routes,bundled packet traffic will be injected into the few waiting queues associated with the optimal routes,leading to load imbalance and congestion risk.To address the congestion avoidance problem,this paper proposes the congestion avoidance algorithm CGR-LB based on waiting queue load balancing.The algorithm proposes metrics to consider queue load and dimensionless metrics to measure routes.In the routing stage,after preprocessing the metric data using linear normalization,the evaluation function is used to obtain the evaluation value of the route by weighting the sum of the two metrics,from which the best route is selected to load balance the waiting queue and avoid subsequent congestion.The simulation experimental results show that the CGR-LB algorithm effectively improves the arrival rate of bundles with little difference in average delay.