A Self-tuning Fuzzy Queue Management Algorithm for Congestion Control

This letter presents an effective self-tuning fuzzy queue management algorithm for congestion control.With the application of the algorithm, routers in IP network regulate its packet drop probability by a self-tuning fuzzy controller. The main advantage of the algorithm is that, with the parameter self-tuning mechanism, queue length can keep stable in a variety of network environments without the difficulty of parameter configuration. Simulations show that the algorithm is efficient, stable and outperforms the popular RED queue management algorithm significantly.     

一种新的模糊控制器设计方法

针对一类非线性系统，将Back-Stepping设计方法同模糊控制技术结合起来，设计了一种新的模糊控制器，给出了这种控制器的性能，并在所有信号一致有界的意义上证明了系统的稳定性，仿真结果表明，该控制器能达到预定的目的。     

An Optimal Flow Control Algorithm for Real-time Traffic over the Internet

According to the Wide Area Network model and queue dynamics in the router, the authors formulate the Internet flow control as a constrained convex programming problem, where the objective is to maximize the total utility and minimize transmission delay and delay jitter of all sources over their transmission rates. Based on this formulation, flow control can be solved by means of a gradient projection algorithm with properly rate iterations. The main difficulty facing the realization of the iteration algorithm is the distributed computation of the congestion measure. Fortunately, Explicit Congestion Notification (ECN) is likely to be used to improving the performance of TCP in the near future. By using ECN, it is possible to realize the iteration algorithm in IP networks. The algorithm is divided into two parts, algorithms in the router and the source. The main advantage of the scheme is its fast convergence ability and robustness, but small queue length fluctuation is unavoidable when the number of users increases.     

An ECN-based Optimal Flow Control Algorithm for the Internet

According to the Wide Area Network model, we formulate Internet flow control as a constrained convex programming problem, where the objective is to maximize the total utility of all sources over their transmission rates. Based on this formulation, flow control can be converted to a normal unconstrained optimization problem through the barrier function method, so that it can be solved by means of a gradient projection algorithm with properly rate iterations. We prove that the algorithm converges to the global optimal point, which is also a stable proportional fair rate allocation point, provided that the step size is properly chosen. The main difficulty facing the realization of iteration algorithm is the distributed computation of congestion measure. Fortunately, Explicit Congestion Notification (ECN) is likely to be used to improve the performance of TCP in the near future. By using ECN, it is possible to realize the iteration algorithm in IP networks. Our algorithm is divided into two parts, algorithms in the router and in the source. The router marks the ECN bit with a probability that varies as its buffer occupancy varies, so that the congestion measure of links can be communicated to the source when the marked ECN bits are reflected back from its destination. Source rates are then updated by all sessions according to the received congestion measure. The main advantage of our scheme is its fast convergence ability and robustness; it can also provide the network with zero packet loss by properly choosing the queue threshold and provide differentiated service to users by applying different utility functions.     

An ECN—based Optimal Flow Control Algroithm for the Internet

According to the Wide Area Network model,we formulate Internet flow control as a constrained convex programming problem,where the objective is to maximize the total utility of all sources over their transmission rates,Based on this formulation,flow control can be converted to a normal unconstrained optimization problem through the barrier function method.so that it can be solved by means of a gradient projection algorithm with properly rate iterations.We prove that the algorithm converges to the global optimal point,which is also a stable proportional fair rate allocation point,provided that the step size is properly chosen.The main difficulty facing the realization of iteration algorithm is the distributed computation of congestion measure.Fortunately,Explicit Congestion Notification (ECN) is likely to be used to improve the performance of TCP in the near future.By using ECN,it is possible to realize the iteration algorithm in IP networks.Our algorithm is divided into two parts,algorithms in the router and in the source.The router marks the ECN bit with a probability that varies as its buffer occupancy varies,so that the congestion measure of links can be communicated to the source when the marked ECN bits are reflected back from its destination.Source rates are then updated by all sessions according to the received congestion measure.The main advantage of our scheme is its fast convergence ability and robustness;it can also provide the network with zero packet loss by properly choosing the queue threshold and provide differentiated service to users by applying different utility functions.     

一种基于全局优化的Internet拥塞控制算法

与传统的基于经验的Internet拥塞控制算法不同，根据广域网络的数学模型，将拥塞控制转化约束非线性规划的全局优化问题，并由此依据凸优化问题的解决方法，设计了满足收敛，稳定和公平性条件的速率迭代算法；依据网络层显示拥塞指示技术的支持，将速率迭代算法分为源端和路由路两部分，从而使该算法可以在IP网络中实现，仿真结果表明了该算法的有效性。