Considering the node heterogeneity, the authors put forward the concept of heterogeneous degrees nodes and construct heterogeneous degrees collection tree. Last but not least, it gets minimum delay content updates tree content update tree by dynamic programming algorithm. 考虑到节点的差异性,提出节点异构度的概念并构建异构度收集树,然后通过动态规划方法求解最小延迟更新内容树。