Research on the QoS Control of Next Generation IP Network

（1）TCP/IP路由器端QoS控制的研究本文的目的之一是提出一种新的路由器端包控制算法，解决V-WFQ问题。在V-WFQ中，如果TCP和UDP连接在路由器处聚合，则吞吐量的公平性降低，并且如果一些连接在路由器处加入或离开，则队列长度变长。针对这些问题，提出了一种利用连续计数器和删除计数器来统计当前活动连接数的算法。我们证实了我们的方法相比，其他传统方法的性能。（2）保证丢包率的快速连接接纳控制研究了稳态时队长尾概率的指数衰减规律，并给出了指数衰减的一个充分条件。研究结果表明，若队长分布函数的Laplace-Stieltjes变换的收敛轴的真实的点为极点，则尾概率呈指数衰减。该结果具有一般性，可以应用于许多类型的队列。这项研究的结果已提交给IEEE transactions。（3）分组网络中延迟时间的估计研究了分组端到端延迟时间的确定性上界。假设业务流由令牌桶算法成形。在这项研究中，我们提出了一个新的上限，这是更准确的比其他传统的界限，注意到聚合突发处理随着时间的推移。通过计算机模拟，我们证实了我们的上界是上级优于其他界。

(1)Study on the QoS control at TCP/IP routerOne of the purposes of this research is to propose a new algorithm of packet control at a router which solves problems of V-WFQ. In V-WFQ, the fairness of throughputs degrades if TCP and UDP connections are aggregated at a router, and the queue length becomes long if some connections join or leave at a router. To solve these problems, we propose an algorithm which uses continuous counter and deleting counter to count the present number of active connections. We confirmed the performance of our method compared to other conventional methods.(2)Study on a fast connection admission control which guarantees the packet loss probabilityWe investigate the exponential decay of the tail probability of the queue length in the steady state and give a sufficient condition for the exponential decay. A result obtained in this research is a theorem that if the real point of the axis of convergence of the Laplace-Stieltjes transform of the distribution function of the queue length is a pole, then the tail probability decays exponentially. This result is so general that it can be applied to many type of queues. The result of this research was submitted to the IEEE transactions.(3)Evaluation of delay time in a packet networkWe study a deterministic upper bound for the end-to-end delay time of a packet. It is assumed that a traffic stream is shaped by a token bucket algorithm. In this study, we proposed a new upper bound which is more accurate than other conventional bounds by noticing that the aggregated burst is processed as time goes. We confirmed that our upper bound is superior to other bounds by computer simulation.