低树代价的低轨卫星网络组播算法

为了解决低轨卫星网络中现有典型源组播算法的信道资源浪费问题,提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法.CCST算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法.在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而大大提高了网络带宽利用率.在w-CCST算法中,通过调整加权因子可以适度增大树代价、降低端到端传播时延,以支持某些时延性能要求严格的实时业务.仿真结果说明,CCST算法的树代价性能比其它算法有显著改善,w-CCST算法的端到端传播时延性能好于CCST算法. 

Multicast routing algorithms with low tree cost for LEO satellite networks

To resolve the channel resources waste problem of the typical source-based multicast routing algorithm in low earth orbit(LEO) satellite networks,a new core-based shared tree algorithm called the core-cluster combination shared tree(CCST) algorithm and its improved one(i.e.w-CCST algorithm) were proposed.The(w-)CCST algorithm consists of the dynamic approximate center(DAC) core selection method and the(weighted) core-cluster combination multicast routing construction method.The core-cluster combination method takes core node and its nearest group member in hops as initial core-cluster,and extends it to construct entire multicast tree step by step by a shortest path scheme between newly-generated core-cluster and surplus group members,which can greatly improve transport bandwidth utilization.In the w-CCST algorithm,a weighted factor was proposed to decrease end-to-end propagation delay and meanwhile increase tree cost a bit to support some real-time applications with strict delay requirements.Simulation results show that tree cost performance of the CCST algorithm is greatly better than that of other algorithms,while end-to-end propagation delay performance of the w-CCST algorithm is better than that of the CCST algorithm.