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为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文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。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。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,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。
In order to solve the problem of channel resource waste of typical source multicast algorithm in LEO satellite IP network, a set of single-core shared tree multicasting algorithm is proposed in this paper, that is, the core group merge and share tree (CCST) (w-CCST) algorithm. The CCST algorithm includes a dynamic approximation center (DAC) selection method and a core group combining and multicast path construction method. The DAC method is proposed for low-orbit satellite networks that periodically and regularly move without the need for complex on-board calculations. In the core group combination method, using the core node as the initial core group, the shortest path of the core group and the remaining group members is gradually extended until the construction of the entire multicast tree is completed, so that the tree cost of the multicast tree is minimized and greatly increased Network bandwidth utilization and multicast transmission efficiency. The weighting factor proposed in the w-CCST algorithm can adjust the compromise between the tree cost and the end-to-end propagation delay, so the tree cost can be modestly increased by adjusting the weighting factors and the end-to-end propagation delay can be reduced to support Some end-to-end delay demanding real-time multicast services. Finally, compared with the typical algorithms in LEO satellite IP network, the simulation results show that the average tree cost of CCST algorithm is significantly lower than that of other algorithms, and the average end-to-end propagation delay of w-CCST algorithm is less than that of CCST algorithm.