中文摘要：

针对基于效用的单层调度模型对网络流划分粒度较粗,难以实现服务间效用公平和总效用最大化的问题,提出了U-S两层调度模型,设计了高效求解算法USMS,为提高求解精度,进一步提出了USIM算法.仿真实验结果显示：USMS和USIM算法具有良好的求解有效性和效率;与单层模型相比,U-S模型具有更高的总效用值.

英文摘要：

Due to the shortcoming of coarse partitioning granularity, utility-based single layer scheduling model fails to achieve good fairness among services and to maximize the whole utility.A two-layer hierarchical scheduling model named U-S as well as the corresponding algorithm USMS to solve the model is proposed. In order to improve the accuracy of the solution, we further design an improved algorithm named USIM. The evaluation experiments show that both USMS and USIM can achieve high solving effectiveness and efficiency and also have higher average whole utility than the single-layer model.