Transmission Control Protocol/active Queue Management Research Articles

Congestion tracking control of multi-bottleneck TCP networks with input-saturation and dead-zone

<abstract><p>This paper discusses the congestion control challenges in a network employing multi-bottleneck Transmission Control Protocol/Active Queue Management (TCP/AQM). The study specifically focuses on networks characterized by input nonlinearity and unknown disturbances. We regard the network as a whole, and consider the influence between multiple nodes and unknown disturbance, a dynamic model of multi-bottleneck network is established. And the impact of dead zone and saturation on the system is taken into account for the first time in the model, the builded TCP/AQM model is more practicable. Based on the characteristics of fuzzy logic systems (FLS), combined with backstepping technology and Lyapunov function, an adaptive congestion control algorithm is designed to make full use of the link resources of each node and improve the network utilization. Ultimately, the proposed algorithm's efficacy and superiority are substantiated through simulation.</p></abstract>

Simulation model of ANN and PID controller for TCP/AQM wireless networks by using MATLAB/Simulink

<p>The wireless network transmission control protocol/active queue management (TCP/AQM) is a network that was chosen as a topic for research a basis is laid to simulate the proposed network and to conduct the simulation under certain conditions. To manage the queue control protocol (TCP/AQM) was chosen. The solution for many modern systems depends on placing additional units called controllers, which work to improve the performance of the work of the systems. The current simulation system can be described according to the test cases that were conducted, where four test cases were identified with sequential steps. In this work there are two control methods by simulation and mathematical model of wireless network TCP/AQM with proportional, integral and derivative (PID) controller and neural network. Simulation is conducted for cases in order to determine the performance of each case through comparison according to appropriate criteria to determine the best. The first case is a wireless communication network system with with a traditional controller PID type. The second is a wireless communication network system, a large neural network controller. Simulations were conducted to choose the best methods among those suggested for nonlinear systems and to enhance and achieve the possibility of adopting MATLAB to perform the required simulation.</p>

Flower Pollination Algorithm to Tune PID Controller of TCP/AQM Wireless Networks

The current study aims to conduct a simulation that is useful in developing an appropriate design that addresses the problem of congestion in the Internet network through controlling the queue of the router. The simulation is conducted through the proposed model for simulation with different control systems that help in raising the quality of performance such as traditional Proportional Integral Derivative (PID) and advanced optimal by Flower Pollination Algorithm (FPA). It depends for Transmission Control Protocol/ Active Queue Management( TCP/AQM )simulation model for a linear system and another non-linear system. To adjust the network work and raise the level of performance, different control systems were chosen, taking into account all the things that appear through conducting experiments and for different purposes. One of the most important things that must be taken into consideration is the system disturbances as a result of the volume and values of the data, causing congestion . It was shown through the results of the experiments that were conducted considering the cases of the linear and nonlinear system to pass data traffic in the network and by adopting the different techniques of the control units, the preference of optimizasion systems over the traditional ones, as well as the preference of the traditional over without control in close loop, is the improvement of the performance of linear systems compared to the open and closed system without control. The simulation results showed that very clear the superiority of the optimization by FPA-PID controller over the conventional system (PID) , as well as very clear the superiority of the traditional system (PID)over closed system without control and open loop system.

Robust control of congestion in computer networks: An adaptive fractional-order approach

In this study, the congestion problem of computer networks is solved by introducing an adaptive fractional-order controller. The controller is designed to enhance the efficiency of nonlinear transmission control protocol/active queue management (TCP/AQM) in these networks. External disturbances can perturb the data transmission. Moreover, factors such as undetermined link capacity can affect the congestion control problem. Hence, the proposed controller should guarantee robustness against disturbances and uncertainties. Besides, small elapsed time to reach the desired queue length as well as convergence of tracking error to zero are essential in queue management. These objectives are fulfilled by designing a fractional-order controller. High tracking capability and robustness make the controller an effective method for TCP/AQM networks. Furthermore, asymptotic stability of the network is precisely proven based on the fractional-order Lyapunov lemma. A variety of simulations are performed to examine capability of the proposed method confronting disturbances and uncertainties while providing a fast and stable response with zero tracking error. The results are also compared with the results of two recently developed control approaches for congestion problem, using performance indices, which confirm the efficiency and superiority of the introduced controller.

Stability analysis of PD AQM control for delay models of TCP networks

ABSTRACT This paper focuses on the local stability analysis of nonlinear delay models of transmission control protocol/active queue management (TCP/AQM) networks by using a Proportional-Derivative (PD) controller as AQM strategy. More precisely, we derive the complete set of PD controllers that exponentially stabilises the corresponding linear delay system. Nonlinear sufficient stability conditions for the local asymptotic stability of the equilibrium are derived by means of the Lyapunov–Krasovskii functional approach. The robustness issue to uncertainty in the network parameters is also addressed. The results are illustrated by means of some numerical examples.

Neural Network-Based Distributed Adaptive Pre-Assigned Finite-Time Consensus of Multiple TCP/AQM Networks

In this study, a class of finite-time consensus of multiple transmission control protocol/active queue management (TCP/AQM) networks is investigated on the basis of a design idea of multi-agent systems, and for the first time, to our knowledge, a novel congestion control concept with neural networks is proposed. First, the problem statement and design goal of the consensus of multiple TCP/AQM networks is given. Then, a pre-assigned finite-time function is introduced to ensure that the tracking error approaches a pre-defined area within finite time. Furthermore, by combining a barrier Lyapunov function and backstepping technique, a neural network-based distributed adaptive finite-time control protocol for the output consensus of multiple TCP/AQM networks is presented, which can effectively generate the desired controls and ensure that the convergent time of all errors has nothing to do with the initial condition and design parameters. In addition, all signals in the closed-loop system are bounded. Finally, an example is given to further illustrate the effectiveness of the theoretical finding presented.

Stability of TCP/AQM Networks Under DDoS Attacks With Design

The current Internet is dramatically suffering the Distributed Denial of Service (DDoS) attacks, in which the perpetrator maliciously makes network resource unavailable to its intended users by temporarily or indefinitely disrupting the services of a host connected to the Internet. In this paper, we investigate an Internet transmission control protocol/active queue management (TCP/AQM) router subject to DDoS attacks. We utilize the time delay control theory to analyze the dynamics of the congestion control windows, and the queues at the router. We derive some explicit conditions under which the TCP/AQM system under DDoS attacks is asymptotically stable. We discuss the convergence of the queue lengths in the router. Our results suggest that, if the network parameters in the TCP window updating, and control parameters in the AQM algorithm satisfy certain conditions, the TCP/AQM system is stable, and its queue lengths can converge to any given target. This result is important, and promising in terms of applications in that, when the DDoS attacked traffic is differentiated from the legitimate traffic, one is able to choke the DDoS attacks by limiting their rates, and then to improve the bandwidth usage of the normal flows. We illustrate the theoretical results using the network simulation platform $ns2$ , and demonstrate that the controlled network can achieve good performance, enhancing the Internet robustness, and performance against DDoS attacks.

Adaptive Finite-Time Congestion Control for Uncertain TCP/AQM Network with Unknown Hysteresis

The issue of adaptive practical finite-time (FT) congestion control for the transmission control protocol/active queue management (TCP/AQM) network with unknown hysteresis and external disturbance is considered in this paper. A finite-time congestion controller is designed by the backstepping technique and the adaptive neural control method. This controller guarantees that the queue length tracks the desired queue in finite-time, and it is semiglobally practical finite-time stable (SGPFS) for all the signals of the closed-loop system. At last, the simulation results show that the control strategy is effective.

Study on TCP/AQM network congestion with adaptive neural network and barrier Lyapunov function

A novel network congestion algorithm is introduced for Transmission Control Protocol/Active Queue Management (TCP/AQM) system in this paper. The established TCP/AQM system is more accurate and general. Moreover, an adaptive congestion controller is designed by virtue of the Barrier Lyapunov Function (BLF), backstepping-like and Neural Networks (NNs) approximation techniques, by which the transient and steady-state performances on the tracking error can be pre-given and other signals of the closed-loop system also are verified to be semi-globally, uniformly and ultimately bounded. Finally, a comparison example is considered to demonstrate the feasibility and superiority of the presented scheme.

Adaptive fuzzy funnel congestion control for TCP/AQM network

In this paper, a performance constraint control problem is considered for Transmission Control Protocol/Active Queue Management (TCP/AQM) network with external disturbance and input saturation. On the basis of backstepping-like design procedure and fuzzy approximation technique, an adaptive fuzzy controller with prescribed constraint is achieved to ensure that the transient and steady state performances of the tracking errors can be satisfied. The stability analysis proves that all the signals in the closed-loop system are semi-globally, uniformly and ultimately bounded. The simulation results clarify the feasibility and effectiveness of the proposed approach.

Adaptive neural practically finite-time congestion control for TCP/AQM network

Inspired by the prescribed performance control (PPC), a new performance function, called finite-time performance function (FTPF), is first defined in this paper, by which a novel finite-time control design process is introduced. This work is also the first to solve the finite-time control issue for a class of transmission control protocol/active queue management (TCP/AQM) networks. Meanwhile, with the aid of FTPF, PPC and neural networks, a new adaptive practically pre-assigned finite-time controller is designed, which guarantees that the queue length q(t) tracks the desired queue qref in finite-time and all the signals of the closed-loop system are semi-globally practical finite-time stable (SGPFS). Finally, simulation results are shown to illustrate the effectiveness of the proposed method.

Comparative analysis of the performance of various active queue management techniques to varying wireless network conditions

This paper demonstrates the robustness of active queue management techniques to varying load, link capacity and propagation delay in a wireless environment. The performances of four standard controllers used in Transmission Control Protocol/Active Queue Management (TCP/AQM) systems were compared. The active queue management controllers were the Fixed-Parameter Proportional Integral (PI), Random Early Detection (RED), Self-Tuning Regulator (STR) and the Model Predictive Control (MPC). The robustness of the congestion control algorithm of each technique was documented by simulating the varying conditions using MATLAB® and Simulink® software. From the results obtained, the MPC controller gives the best result in terms of response time and controllability in a wireless network with varying link capacity and propagation delay. Thus, the MPC controller is the best bet when adaptive algorithms are to be employed in a wireless network environment. The MPC controller can also be recommended for heterogeneous networks where the network load cannot be estimated.

Congestion tracking control for uncertain TCP/AQM network based on integral backstepping

An H∞ congestion tracking control problem for nonlinear transmission control protocol/active queue management (TCP/AQM) network is proposed in this paper. Inspired by the existing network models, a modified TCP/AQM network model with external disturbance and modelling uncertainty is first introduced. And then, a novel function for the desired queue length is defined for the first time, which can simulate the changes in the queue length during a day. Next, a novel AQM scheme is presented to control network congestion by combining H∞ theory and integral backstepping technique. The proposed method guarantees that the better tracking performance of the queue is achieved, and all the signals are asymptotically stable in the closed-loop system in probability. Finally, the effectiveness of the presented algorithm is tested by simulation results.

Adaptive backstepping H∞ tracking control with prescribed performance for internet congestion

This paper extends the well-known control method, prescribed performance control (PPC), to network congestion control problems. An adaptive H∞ tracking problem for Transmission Control Protocol/Active Queue Management (TCP/AQM) system with external disturbance is studied. Firstly, a modified network model is given. And then, the model is changed to an equivalent error model by using error transformation. Next, to solve the network congestion problem, prescribed performance, backstepping technique, adaptive control and H∞ control are combined to design a congestion controller. Due to the use of prescribed performance, the controller can guarantee both the transient and steady state performance of the system. Meanwhile, the output of the system can track the desired queue, and unknown link capacity can be estimated. Finally, a simulation result is shown to clarify the feasibility and effectiveness of proposed approach.

A New DiffServ Edge Router with Controlled‐UDP

The existing edge routers can not assign the link capacities between User datagram protocol (UDP) subscribers and Transmission control protocol (TCP) subscribers to ensure the multiple priorities traffics with Differentiate-Serve (DiffServ). To solve the problem, a new DiffServ edge router with Controlled-UDP (C-UDP) is proposed. The proposed DiffServ edge router can control the data rates of UDP and TCP subscribers according to their priorities. In the proposed edge router, there are multi-queues buffers controlled by TCP Active queue management (AQM) and UDP AQM algorithms to implement fair and stable link capacities. The proposed TCP AQM and UDP AQM algorithms achieve the network congestion control and DiffServ by operating AQM parameters on the stable conditions proposed by us. The dynamic simulation results demonstrate the proposed edge router for DiffServ network to be valid.

Design of the Congestion Control for TCP/AQM Network with Time-Delay

The purpose of this paper is to design congestion controller for TCP/AQM (transmission control protocol/active queue management) networks using model following control; the equilibrium of a class of TCP/AQM networks with time-delay is investigated, and the effect of communication time-delay on the stability is addressed. The features of this design method are bounded property of the internal states of the control system being given and the utility of this control. Such design exhibits important attributes including fast convergence with high accuracy to a desired queue length. Simulation results show that the time-delay nonlinear behavior of the system can be controlled by this method.

Adaptive mechanism-based congestion control for networked systems

In order to assure the communication quality in network systems with heavy traffic and limited bandwidth, a new ATRED (adaptive thresholds random early detection) congestion control algorithm is proposed for the congestion avoidance and resource management of network systems. Different to the traditional AQM (active queue management) algorithms, the control parameters of ATRED are not configured statically, but dynamically adjusted by the adaptive mechanism. By integrating with the adaptive strategy, ATRED alleviates the tuning difficulty of RED (random early detection) and shows a better control on the queue management, and achieve a more robust performance than RED under varying network conditions. Furthermore, a dynamic transmission control protocol–AQM control system using ATRED controller is introduced for the systematic analysis. It is proved that the stability of the network system can be guaranteed when the adaptive mechanism is finely designed. Simulation studies show the proposed ATRED algorithm achieves a good performance in varying network environments, which is superior to the RED and Gentle-RED algorithm, and providing more reliable service under varying network conditions.

Traffic monitoring in transmission control protocol/active queue management networks through a time-delay observer

The use of the control theory tools for traffic control in communication networks, for example, the congestion control in internet protocol (IP) routers, has given rise to challenging issues in the time-delay system framework. In this study, the authors propose to design a linear time-delay observer for traffic monitoring in transmission control protocol/active queue management (TCP/AQM) networks. More precisely, the authors focus on a bottleneck topology consisting of long-lived TCP communications through a router. The developed mechanism, located at the router, aims at supervising the network via TCP flow estimations as well as detecting a class of anomalies. This issue is formulated as a stability problem for multiple delayed systems and appropriate robust control tools such as quadratic separation are adopted to address it. Then, some simulations via the network simulator NS-2 and an emulation experiment support the proposed methodology.

Computing non-fragile PI controllers for delay models of TCP/AQM networks

This article focuses on the stabilisation problem of fluid-flow delay models of transmission control protocol/active queue management (TCP/AQM) networks by using a proportional-integral (PI) controller as AQM strategy. More precisely, the complete set of PI controllers that exponentially stabilises the corresponding linear time-delay system is derived. Using the particular geometric properties of this set of the controller parameters, the issues of robustness to uncertainty in the network parameters and to perturbation in the controller coefficients are addressed. Then, a methodology to compute a non-fragile PI AQM controller is provided. Finally, exponential estimates for the closed-loop system solutions, allowing to evaluate the performance of the corresponding PI-controlled closed-loop system, are proposed by using a Lyapunov–Krasovskii functional approach. An illustrative example completes the presentation.

A Design of Gain-scheduled Congestion Controllers using State Predictive Observers

Abstract In this paper, a design problem of congestion controllers is discussed for TCP/AQM(Transmission Control Protocol/Active Queue Management) networks. The proposed method consists of two control techniques. First one is based on a gain-scheduling technique considering nonlinearities of TCP/AQM networks. But the designed congestion controller is a state feedback controller and it is impossible to embed the congestion controller in real computer networks. To avoid this problem, second one is based on a design technique of state predictive observer for linear time-delay systems. Thus it can be possible to embed the congestion controller in real networks by combining these methods. Firstly dynamical models of TCP/AQM are described as linear systems with self-scheduling parameters, which also depend on information delay. Here it is distinguishing to focus on constraints on the maximum queue length and TCP window-size, which are the network resources in TCP/AQM networks. And a design method of memoryless state feedback controllers is shown for linear system with a self-scheduling parameter and an information delay. But the designed gain- scheduled congestion controller is a state feedback controller and it is impossible to apply this controller to computer networks directly. Thus observers are also designed and the observer-based congestion controllers are derived.