Research on the QoS Control of Next Generation IP Network

(1) TCP/IP路由器的QoS控制研究本研究的目的之一是提出一种新的路由器分组控制算法，解决V-WFQ问题。在V-WFQ中，如果在一台路由器上聚合TCP和UDP连接，吞吐量的公平性会降低，如果在一台路由器上有一些连接加入或离开，队列长度会变长。为了解决这些问题，我们提出了一种使用连续计数器和删除计数器来计算当前活动连接数的算法。与其他传统方法相比，我们证实了该方法的性能。(2)保证丢包概率的快速接入控制研究我们研究了稳定状态下队列长度尾部概率的指数衰减，给出了指数衰减的充分条件。本文得到的一个定理是，如果队列长度分布函数的Laplace-Stieltjes变换的收敛轴实点为极点，则尾部概率呈指数衰减。这个结果非常普遍，可以应用于许多类型的队列。该研究结果已提交给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。假设流量流是由令牌桶算法形成的。在这项研究中，我们提出了一个新的上界，它比其他传统的上界更准确，因为我们注意到聚合的突发是随着时间的推移而处理的。通过计算机模拟，证实了我们的上界优于其他的上界。

(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.