Prescribed Performance Tracking Control of Time-Delay Nonlinear Systems With Output Constraints

The problem of prescribed performance tracking control for unknown time-delay nonlinear systems subject to output constraints is dealt with in this paper. In contrast with related works, only the most fundamental requirements, i.e., boundedness and the local Lipschitz condition, are assumed for the allowable time delays. Moreover, we focus on the case where the reference is unknown beforehand, which renders the standard prescribed performance control designs under output constraints infeasible. To conquer these challenges, a novel robust prescribed performance control approach is put forward in this paper.Herein, a reverse tuning function is skillfully constructed and automatically generates a performance envelop for the tracking error. In addition, a unified performance analysis framework based on proof by contradiction and the barrier function is established to reveal the inherent robustness of the control system against the time delays. It turns out that the system output tracks the reference with a preassigned settling time and good accuracy,without constraint violations. A comparative simulation on a two-stage chemical reactor is carried out to illustrate the above theoretical findings.

Internet end-to-end delay dynamics

End-to-end delay is one of the most important characteristics of Internet end-to-end packet dynamics, which can be applied to quality of services （OoS） management, service level agreement （SLA） management, congestion control algorithm development, etc. Nonstationarity and nonlinearity are found by the analysis of various delay series measured from different links. The fact that different types of links have different degree of Self-Similarity is also obtained. By constructing appropriate network architecture and neural functions, functional networks can be used to model the Internet end-to-end nonlinear delay time series. Furthermore, by using adaptive parameter studying algorithm, the nonstationarity can also be well modeled. The numerical results show that the provided functional network architecture and adaptive algorithm can precisely characterize the Internet end-to-end delay dynamics.

The Distributed Network Monitoring Model with Bounded Delay Constraints

We address the problem of optimizing a distributed monitoring system and the goal of the optimization is to reduce the cost of deployment of the monitoring infrastructure by identifying a minimum aggregating set subject to delay constraint on the aggregating path. We show that this problem is NP-hard and propose approximation algorithm proving the approximation ratio with lnm+1, where is the number of monitoring nodes. At last we extend our modal with more constraint of bounded delay variation. Key words network - distributed monitoring - delay constraint - NP-hard CLC number TP 393 Foundation item: Supported by the National Natural Science Foundation of China (60373023)Biography: LIU Xiang-hui(1973-), male, Ph. D. candidate, research direction: algorithm complexity analysis, QoS in Internet.

Effective multicasting algorithm for dynamic membership with delay constraint

This paper proposes an effective heuristic algorithm The tree constructed by DDMR has the following characteristics： for dynamic multicast routing with delay-constrained DDMR. （1） multicast tree changes with the dynamic memberships; （2） the cost of the tree is as small as possible at each node addition/removal event; （3） all of the path delay meet a fixed delay constraint; （4） minimal perturbation to an existing tree. The proposed algorithm is based on “damage” and “usefulness” concepts proposed in previous work, and has a new parameter bf（Balancing Factor） for judging whether or not to rearrange a tree region when membership changes. Mutation operation in Genetic Algorithm （GA） is also employed to find an attached node for a new adding node. Simulation showed that our algorithm performs well and is better than static heuristic algorithms, in term of cost especially.

QoS Guarantees of Multiuser Video Streaming over Wireless Links: Delay Constraint and Packet Priority Drop

To provide a certain level of Quality of Service (QoS) guarantees for multiuser wireless downlink video streaming transmissions, we propose a multiuser scheduling scheme for QoS guarantees. It is based on the classic Queue-Length-Based (QLB)-rate maximum scheduling algorithm and integrated with the delay constraint and the packet priority drop. We use the large deviation principle and the effective capacity theory to construct a new analysis model to find each user's queue length threshold (delay constraint) violation probability. This probability corresponds to the upper bound of the packet drop probability, which indicates a certain level of statistical QoS guarantees. Then, we utilize the priority information of video packets and introduce the packet priority drop to further improve the quality perceived by each user. The simulation results show that the average Peak Signal to Noise Ratio (PSNR) value of the priority drop is 0.8 higher than that of the non-priority drop and the PSNR value of the most badly damaged video frame in the priority drop is on an average 4 higher than that of the non-priority drop.

Stability of singular networked control systems with control constraint

Based on bounded network-induced time-delay, the networked control system is modeled as a linear time-variant singular system. Using the Lyapunov theory and the linear matrix inequality approach, the criteria for delay-independent stability and delay-dependent stability of singular networked control systems are derived and transformed to a feasibility problem of linear matrix inequality formulation, which can be solved by the Matlab LMI toolbox, and the feasible solutions provide the maximum allowable delay bound that makes the system stable. A numerical example is provided, which shows that the analysis method is valid and the stability criteria are feasible.

A PCA-Based Internet Delay Space Dividing Algorithm

It's a hot issue to improve the accuracy of network coordinate systems(NCS). By analyzing the error source of NCSes, it's emphasized that guaranteeing the low dimensionality of embedding datasets is the principle on the designing of NCSes. Based on this observation, a PCA based Internet delay space dividing algorithm(IDSD-PCA) is proposed. Beginning at choosing an optimized sub dataset randomly, IDSD-PCA partitions the Internet delay dataset into several sub datasets with low dimensionality by iterations. After the partition, the whole delay dataset and sub datasets are embedded into a hierarchical NCS. The experimental results show that with this framework both the metric space based models and the non-metric space based models can predict the end-to-end delays more accurately.

A statistical end-to-end performance model for networks with complex topologies

Network calculus provides new tools for performance analysis of networks, but analyzing networks with complex topologies is a challenging research issue using statistical network calculus. A service model is proposed to characterize a service process of network with complex topologies. To obtain closed-form expression of statistical end-to-end performance bounds for a wide range of traffic source models, the traffic model and service model are expanded according to error function. Based on the proposed models, the explicit end-to-end delay bound of Fractional Brownian Motion（FBM） traffic is derived, the factors that affect the delay bound are analyzed, and a comparison between theoretical and simulation results is performed. The results illustrate that the proposed models not only fit the network behaviors well, but also facilitate the network performance analysis.

A New Delay-Constrained Multicast Routing Algorithm Based on Shared Edges

In this paper, we made a detail analysis for the ESAMPH algorithm, and proposed ESAMPH_D algorithm according to the insufficient of ESAMPH algorithm. The ESAMPH_D algorithm does not consider those paths that do not satisfy the delay constraint, so we can ensure that all paths be taken into account will meet the limit of delay constraint, then we find the least costly path in order to build a minimum cost multicast tree. Simulation results show that the algorithm is better than ESAMPH algorithm in performance.

A delay-constrained energy-efficient component carrier adjusting scheme for LTE-Advanced systems

The energy efficiency and packet delay tradeoffs in long term evolution-advanced(LTE-A) systems are investigated.Analytical expressions are derived to explain the relation of energy efficiency to mean packet delay,arrival rate and component carrier(CC) configurations,from the theoretical respective which reveals that the energy efficiency of multiple CC systems is closely related to the frequency of CCs and the number of active CCs.Based on the theoretical analysis,a CC adjusting scheme for LTE-A systems is proposed to maximize energy efficiency subject to delay constraint by dynamically altering the on/off state of CCs according to traffic variations.Numerical and simulation results show that for CCs in different frequency bands with equal transmit power,the proposed scheme could significantly improve the energy efficiency of users in all aggregation levels within the constraint of mean packet delay.

Real-time Performance Evaluation of Line Topology Switched Ethernet

Recently,switched Ethernet has become an active area of research because of its wide uses in industry.However,its uses have various real-time constraints on data communications.This paper analyzes the performance of the line topology switched Ethernet as a data acquisition network.Network calculus theory,which has been successfully applied to assess the real-time performance of packet-switched networks,is used to analyze the networks.To properly describe the activity of switches,a novel approach of modeling data flows into or out of switches is addressed.Based on our model,a concisely analytical expression of the maximal end-to-end delay in line topology switched Ethernet is derived.Finally,the relative simulation results are demonstrated.These results agree well with the analytical results,and thus they validate the data flow modeling techniques.

Fundamental Issues in Networked Control Systems

Abstract--This paper provides a survey on modeling and theories of networked control systems （NCS）. In the first part, modeling of the different types of imperfections that affect NCS is discussed. These imperfections are quantization errors, packet dropouts, variable sampling/transmission intervals, vari- able transmission delays, and communication constraints. Then follows in the second part a presentation of several theories that have been applied for controlling networked systems. These theories include： input delay system approach, Markovian system approach, switched system approach, stochastic system approach, impulsive system approach, and predictive control approach. In the last part, some advanced issues in NCS including decentral- ized and distributed NCS, cloud control system, and co-design of NCS are reviewed. Index Terms--Decentralized networked control systems （NCS）, distributed networked control systems, network constraints, net- worked control system, quantization, time delays.

A Discrete-Time Traffic and Topology Adaptive Routing Algorithm for LEO Satellite Networks

“Minimizing path delay” is one of the challenges in low Earth orbit (LEO) satellite network routing algo-rithms. Many authors focus on propagation delays with the distance vector but ignore the status information and processing delays of inter-satellite links. For this purpose, a new discrete-time traffic and topology adap-tive routing (DT-TTAR) algorithm is proposed in this paper. This routing algorithm incorporates both inher-ent dynamics of network topology and variations of traffic load in inter-satellite links. The next hop decision is made by the adaptive link cost metric, depending on arrival rates, time slots and locations of source-destination pairs. Through comprehensive analysis, we derive computation formulas of the main per-formance indexes. Meanwhile, the performances are evaluated through a set of simulations, and compared with other static and adaptive routing mechanisms as a reference. The results show that the proposed DT-TTAR algorithm has better performance of end-to-end delay than other algorithms, especially in high traffic areas.

End-to-end delay analysis for networked systems

End-to-end delay measurement has been an essential element in the deployment of real-time services in networked systems. Traditional methods of delay measurement based on time domain analysis, however, are not efficient as the network scale and the complexity increase. We propose a novel theoretical framework to analyze the end-to-end delay distributions of networked systems from the frequency domain. We use a signal flow graph to model the delay distribution of a networked system and prove that the end-to-end delay distribution is indeed the inverse Laplace transform of the transfer function of the signal flow graph. ~vo efficient methods, Cramer＇s rule-based method and the Mason gain rule-based method, are adopted to obtain the transfer function. By analyzing the time responses of the transfer function, we obtain the end-to-end delay distribution. Based on our framework, we propose an efficient method using the dominant poles of the transfer function to work out the bottleneck links of the network. Moreover, we use the framework to study the network protocol performance. Theoretical analysis and extensive evaluations show the effectiveness of the proposed approach.

Optimized Resource Allocation and Queue Management for Traffic Control in MANET

A set of mobile devices that employs wireless transmission for communication is termed Mobile Ad hoc Networks(MANETs).Offering better communication services among the users in a centralized organization is the primary objective of the MANET.Due to the features of MANET,this can directly End-to-End Delay(EED)the Quality of Service(QoS).Hence,the implementation of resource management becomes an essential issue in MANETs.This paper focuses on the efficient Resource Allocation(RA)for many types of Traffic Flows(TF)in MANET.In Mobile Ad hoc Networks environments,the main objective of Resource Allocation(RA)is to process consistently available resources among terminals required to address the service requirements of the users.These three categories improve performance metrics by varying transmission rates and simulation time.For solving that problem,the proposed work is divided into Queue Management(QM),Admission Control(AC)and RA.For effective QM,this paper develops a QM model for elastic(EL)and inelastic(IEL)Traffic Flows.This research paper presents an AC mechanism for multiple TF for effective AC.This work presents a Resource Allocation Using Tokens(RAUT)for various priority TF for effective RA.Here,nodes have three cycles which are:Non-Critical Section(NCS),Entry Section(ES)and Critical Section(CS).When a node requires any resources,it sends Resource Request Message(RRM)to the ES.Elastic and inelastic TF priority is determined using Fuzzy Logic(FL).The token holder selects the node from the inelastic queue with high priority for allocating the resources.Using Network Simulator-2(NS-2),simulations demonstrate that the proposed design increases Packet Delivery Ratio(PDR),decrease Packet Loss Ratio(PLR),minimise the Fairness and reduce the EED.

Multi-level cross-layer protocol for end-to-end delay provisioning in wireless multimedia sensor networks

Rapid developments in information and communication technology in recent years have posed a significant challenge in wireless multimedia sensor networks(WMSNs).End-to-end delay and reliability are the critical issues in multimedia applications of sensor networks.In this paper we provide a new cross-layer approach for provisioning the end-to-end delay of the network at a desirable level of the packet delivery ratio(PDR),used here as a measure of network reliability.In the proposed multi-level cross-layer(MLCL)protocol,the number of hops away from the sink is used to set a level for each node.A packet is routed through the path with the minimum hop count to the sink using this level setting.The proposed protocol uses cross-layer properties between the network and medium access control(MAC)layers to estimate the minimum delay,with which a node can deliver a packet to the sink.When a node wants to send a packet,the MLCL protocol compares this minimum delay with the time to live(TTL)of a packet.If the TTL of the packet is higher than the minimum delay,the node sends the packet through the path with the minimum delay;otherwise,the node drops the packet as the node cannot deliver it to the sink within the TTL duration.This packet dropping improves network performance because the node can send a useful packet instead of an unusable packet.The results show a superior performance in terms of end-to-end delay and reliability for the proposed protocol compared to state-of-the-art protocols.

New Approach of QoS Metric Modeling on Network on Chip

This paper presents a new NoC QoS metrics modeling shaped on mesh architecture. The new QoS model is based on the QoS parameters. The goal of this work is to quantify buffering requirements and packet switching techniques in the NoC nodes by analyzing some QoS metrics such as End-to-End delays (EEDs) and packet loss. This study is based on simulation approach of a 4 × 4 mesh NoC behavior under multimedia communication process. It proposes a study of NoC switching buffer size avoiding packet drop and minimizing EED. Mainly, we focus on percent flit losses due to buffer congestion for a network loading. This leads to identify the optimal buffer size for the switch design. The routing approach is based on the Wormhole Routing method.

Routing Multipoint Connections in Packet-Switched Computer Networks

The problem of constructing minimum cost multicast trees with end to end delay and delay variation constraints to meet the quality of service requirements in high speed packet switched environments is studied in this paper. The routing problem of the bounded delay along the paths from the source to each destination and the bounded variation among the delays along these paths is disussed, and then a new algorithm based on Hopfield neural networks to optimize the multicast tree with delay and variation constraints is presented. The simulations show that the proposed algorithm achieves its best performance in high speed computer networks.

A method for measuring the clock offset of two hosts in the network

In order to detect the performance parameters of the network, for example, the network delay or delay jitter, the clock synchronization relations between the two hosts at two ends along the network must be calculated in advance. Then with the correct temporal relations between the two hosts, multimedia transmission along the network and display can occur by the proper order. A refined method based on Paxson's algorithm is proposed and testified. More accurate results can be attained by the method. By the way, the method can be used in a more complicated environment. Furthermore, an end-to-end network performance tester based on the proposed algorithm is designed and implemented.

Cross-Layer Hidden Markov Analysis for Intrusion Detection

Ad hoc mobile cloud computing networks are affected by various issues,like delay,energy consumption,flexibility,infrastructure,network lifetime,security,stability,data transition,and link accomplishment.Given the issues above,route failure is prevalent in ad hoc mobile cloud computing networks,which increases energy consumption and delay and reduces stability.These issues may affect several interconnected nodes in an ad hoc mobile cloud computing network.To address these weaknesses,which raise many concerns about privacy and security,this study formulated clustering-based storage and search optimization approaches using cross-layer analysis.The proposed approaches were formed by cross-layer analysis based on intrusion detection methods.First,the clustering process based on storage and search optimization was formulated for clustering and route maintenance in ad hoc mobile cloud computing networks.Moreover,delay,energy consumption,network lifetime,and link accomplishment are highly addressed by the proposed algorithm.The hidden Markov model is used to maintain the data transition and distributions in the network.Every data communication network,like ad hoc mobile cloud computing,faces security and confidentiality issues.However,the main security issues in this article are addressed using the storage and search optimization approach.Hence,the new algorithm developed helps detect intruders through intelligent cross layer analysis with theMarkov model.The proposed model was simulated in Network Simulator 3,and the outcomes were compared with those of prevailing methods for evaluating parameters,like accuracy,end-to-end delay,energy consumption,network lifetime,packet delivery ratio,and throughput.