Research On Load Based Adaptive Routing For Satellite Networks

Since satellite networks have a wide range of geographic coverage and long communication distance without geographic restrictions,satellite networks play an important role in the global communications.The unbalanced distribution of population which is caused by geographical factors results in the unbalanced distribution of traffic in satellite networks.In addition,the unbalanced load results in higher end-to-end delay and packet drop rate,influencing the performance of satellite networks.We propose a load based adaptive routing for satellite networks to balance load.Due to the highly dynamic changes in satellite networks,there exists short-time light traffic in the links,which affects the calculation of queuing delay and the selection of routes and also makes the satellite networks perform worse.Firstly,we propose an adaptive estimated queuing delay model,which filters the short-time light traffic and provides more effective queuing delay.Secondly,we propose a load based adaptive routing algorithm,which adjusts the routing adaptively based on the load of satellite to balance the traffic distribution.The main contributions of this thesis can be summarized as follows:1.An adaptive estimated queuing delay model is proposed,which filters short-time light load and adjusts the value of estimated queuing delay adaptively based on the past estimated queuing delay and the current average expected queuing delay.The proposed model provides a more effective queuing delay for the global route computation in satellite networks.2.A load based adaptive routing algorithm for satellite networks is designed.The routing algorithm adjusts route dynamically with the route state model in order to make full use of network resources and to balance load.3.The computation method of state transition probabilities in the route state model is proposed.The state transition probabilities are based on the real-time load state and the cost of global route,aiming at the load balancing and low end-to-end delay.The load based adaptive routing for satellite networks is implemented by NS2 and compared with the representative satellite routing algorithm which aims at load balancing.The simulation results show that the proposed routing performs better in terms of end-to-end delay,packet drop rate,throughput and distribution of traffic.