中文摘要：

基于二层QBDs（quasi birth-death models），提出了一个（X,S）-bottleneck区域性能分析模型，（X,S）-bottleneck区域的特征通过第1层QBD模型描述，而经过（X,S）-bomeneck区域的每条流的特征由第2层QBD模型描述．基于该性能分析模型，对优却．bottleneck区域的性能进行了一些概率分析，如（X,S）-boaleneek区域的平衡状态概率、经过该区域通信流的成功转发概率和吞吐量等，确定了上述概率及吞吐量的取值范围．仿真实验结果表明了该性能分析模型对于分析（X,S）-bottleneck区域性能的有效性．结论有助于无线网络通信性能的改进和管理．

英文摘要：

The performance analytical model for （X,S）-bottleneek cell is proposed and perform some probabilistic analysis on the perforrnanees of （X,S）-bottleneck cell, such as the probability of balance state, the transmission probability of a flow, and the throughput of （X, S）-bottleneck cell. To capture the essential aspects of （X,S）- bottleneck cell, two-hierarchy Quasi Birth-Death models （QBDs） are used to model the （2t＇,S）-bottleneck cell. The general characters of （X,S）-bottleneck cell are govern by the first hierarchy QBDs, while the characters of each flow are captured by the second hierarchy QBDs. Based on the analytical model, a methodology to derive the balance-state probability of （X,S）-bottleneck cell is proposed, and some theoretic ranges for the transmission probability of a flow and the throughput. The simulations show that the proposed model can analyze effectively the performance of （X, S）-bottleneck cell. The results are helpful for improving and managing wireless networks.