A Modified Traffic-Light Routing Algorithm Based On Various QoS Demands In NGEO Satellite Networks

In recent decades,there have been a lot of researches on NGEO satellite networks,which have obvious advantages over GEO satellites,such as lower orbits,shorter end-to-end delay,less demand for the power of ground terminals and so on.However,with the development of satellite communication technology,the rapid growth of the ground user traffics have become a huge challenge to the limited space resources.Besides,due to the uneven distribution in space the sudden in time of user traffics,it is likely to cause the "hot spot" problem,which means that a few satellite nodes in the network work under the heavy load and drop too many packets at certain times while other nodes are fairly free.Firstly this article proposes a routing algorithm based on various QoS demands and load balancing applied for NGEO satellite networks.We research the service requirements of different users in detail,and the link cost and the state information of three types of flows are defined.Besides,the definitions are used for the modified traffic-light routing algorithm to achieve better load balancing.In the modified traffic-light routing algorithm,a set of traffic lights are used to indicate the congestion status at both the current node and the next node.When a packet travels along a pre-calculated route to the destination,it may adjust the route dynamically,according to the real-time color of traffic lights at each intermediate node.Through the combination of preliminary planning and real-time adjustment,each packet can eventually get an approximately optimal transmission path.Secondly this paper also studies the characteristics of bandwidth allocation in satellite networks,and analyzes the allocation schemes by the bargaining game theory.Aiming at the packets scheduling problem,a reasonable profit model is constructed,to compute the maximum gain points of satellite network system.Based on this we can get the best recourse allocation scheme.Finally in this paper a Iridium-like satellite network is designed on NS2 platform,in which we realizes the modified traffic-light routing algorithm based on various QoS demands in NGEO satellite networks.Then on MATLAB simulation platform we analyze the performance of the modified traffic-light routing algorithm,including the end-to-end delay,total throughput of networks,packet loss rate and bandwidth utilization.