Packet-switched Communication Networks Research Articles

Batch poissonian arrival models of multiservice network traffic

The emergence of packet-switched communication networks has made it clear that Poissonian arrival flow models are not quite adequate and required the development of new models based on non-Poisson distributions. This paper is devoted to the analysis of a particular case of a batch Markovian flow, namely, batch (nonordinary) Poissonian arrivals. Such a flow is stationary and memoryless but not ordinary. We consider a class of queueing systems with constant service time. We present results of analytical computations of arrival flow parameters and also simulation results. We show that the variance of the queue depends on the third moment of the batch size in a batch Poissonian arrival flow.

A routing method with adaptively adjusting memory information based on local routing history.

Finding the shortest paths for packets from sources to destinations in packet-switched communication networks is an inevitable problem in building a future high-speed information society. A routing method with memory information has already been proposed to alleviate the congestion of large volumes of packet flow. This routing method shows a high transmission completion rate even for large volumes of packet flows in communication networks with scale-free properties. However, the method exhibits poor performance for networks with local triangular connections and long distances between nodes. To overcome these problems, in this study, we first enhanced the routing performance of the conventional communication network models by using the betweenness centrality of nodes, which is one of the network centralities that measures the number of shortest paths that pass through each node in the networks. Subsequently, we adaptively changed the transmitting paths of packets by using only local information. Numerical simulations indicated that our routing method performs successfully for various topologies of communication networks by avoiding the congested node, and effectively using the memory information.

Method for calculation indicators steganographic systems in multiservice communication networks

An analysis of the performance indicators multiservice telecommunication networks using the sixth technological order based on the NGN (Next Generation Network) architectural concept and future FN (Future Networks) networks was carried out to build high-performance steganographic systems with increased covert channels throughput, ensuring the achievement of a certain level information security. Comprehensive criteria for the efficiency the functioning steganographic systems are considered and the channel capacity of the steganosystem as a communication system with packet switching is selected. On the basis of the study, a new approach to constructing a method for evaluating complex indicators of the quality of steganographic communication during embedding and extracting hidden data is proposed. The quality of steganographic communication refers to the properties stegano communication to ensure the efficiency of the system, both timely and reliable transmission of messages. On the basis of the proposed approach, the effectiveness steganographic systems in the construction of covert channels for the transmission secret data transmitted over communication channels was studied. Taking into account the new entropy approach, a method for calculating the indicators of the latent throughput steganographic systems in packet-switched communication networks has been created. As a result of the study calculation method, important analytical expressions were obtained for evaluating complex indicators throughput steganographic systems, such as the throughput of covert channels, the maximum possible value of the performance of a binary source packets, the average packet transmission time with the proposed coding scheme, and the residual throughput of the communication channel.

RESEARCH EFFICIENCY OF STEGANOGRAPHIC SYSTEMS IN EMBEDDING OR EXTRACTING HIDDEN INFORMATION

The performance indicators multiservice telecommunication networks based on the architectural concept of the next Next Generation Network (NGN) and Future Networks (FN) are analyzed, using promising steganographic methods, algorithms and technologies that support a wide range cryptographic strength. As a criterion for complex indicators of the effectiveness steganographic systems, both the throughput of the covert channel, the channel utilization factor, and the probabilistic-temporal characteristics are chosen. The issues constructing covert channels, taking into account the length service packets for transmitting covert data, are considered. As a result of the study, a new approach to the construction of a mathematical model (MM) of the bandwidth steganographic systems as a communication system is proposed, which is based on the entropy approach. On the basis of the model, complex indicators effectiveness steganographic systems are studied, taking into account the parameters of the threat and stability of steganosystems. On the basis MM, the maximum throughput of a covert channel is investigated, taking into account the informative characteristics of steganographic systems. Analytical expressions have been obtained to evaluate the complex indicators steganographic systems for hiding data transmitted over communication channels when embedding and when extracting data with the necessary parameters. A numerical analysis was carried out and a graphical dependence of the maximum throughput of a covert channel on the channel utilization factor was plotted for a given system speed. Based on the results obtained, one can judge the effectiveness of modern steganographic systems in embedding and extracting hidden multimedia type data in packet-switched communication networks.

Оценка эффективности метода синтеза мультисервисной сети связи

The article proposes directions for evaluating the efficiency of the multiservice communication network structure variant, and on the basis of euclidean heuristics, an approach to evaluating the efficiency of the method of synthesizing a multiservice packet-switched communication network consisting in searching for a structure on a limited set of vertices connected by minimum edges by weight, which is a set of independent spanning trees on a limited subset of minimum connections. It is proposed to assess the effectiveness of the method of synthesizing a multiservice communication network for connected saturated graphs, since an accurate analysis of the effectiveness of euclidean heuristics is a difficult analytical task and very significantly depends on both the number and location of vertices and the number of edges incident by it. The given version of estimation of efficiency of method of synthesis of multiservice communication network is based on results of multivariate computational experiment for random saturated graphs, upper limits of characteristics of which are obtained from normative and technical documentation by evaluation analysis of values of parameters of promising multiservice communication networks. Assessment of the set of main and additional actions when searching for the required number of independent spanning trees, the structure of the multiservice communication network in comparison with the Prima algorithm allows us to conclude that, that the synthesis method under consideration enables to obtain a rational solution to the structure synthesis problem, constituting a multiservice communication network in an acceptable time compared to known synthesis methods; which, according to the results of statistical tests for the considered practically important subset of implementation options for promising multiservice communication networks, is two to three times less than the estimate of the time for performing a search on a set of all vertices.

A Survey of Fast-Recovery Mechanisms in Packet-Switched Networks

In order to meet their stringent dependability requirements, most modern packet-switched communication networks support fast-recovery mechanisms in the data plane. While reactions to failures in the data plane can be significantly faster compared to control plane mechanisms, implementing fast recovery in the data plane is challenging, and has recently received much attention in the literature. This survey presents a systematic, tutorial-like overview of packet-based fast-recovery mechanisms in the data plane, focusing on concepts but structured around different networking technologies, from traditional link-layer and IP-based mechanisms, over BGP and MPLS to emerging software-defined networks and programmable data planes. We examine the evolution of fast-recovery standards and mechanisms over time, and identify and discuss the fundamental principles and algorithms underlying different mechanisms. We then present a taxonomy of the state of the art, summarize the main lessons learned, and propose a few concrete future directions.

Discrete Sliding Mode Control Design for Bilateral Teleoperation System via Adaptive Extended State Observer.

The goal of this paper is to improve the synchronization control performance of nonlinear teleoperation systems with system uncertainties in the presence of time delays. In view of the nonlinear discrete states of the teleoperation system in packet-switched communication networks, a new discrete sliding mode control (DSMC) strategy is performed via a new reaching law in task space. The new reaching law is designed to reduce the chattering and improve control performance. Moreover, an adaptive extended state observer (AESO) is used to estimate the total system disturbances. The additional gain of AESO is adjusted in time to decrease the estimation errors of both system states and disturbances automatically and improve the estimation performances of the AESO. Finally, the validity of the designed control strategy is demonstrated by both simulation and experiments. Furthermore, the experimental comparison results indicate that the improvement is achievable with the proposed AESO and DSMC.

A Survey on Network Calculus Tools for Network Infrastructure in Real-Time Systems

Network Calculus is an established analytical framework which can provide deterministic estimates of latency and buffer requirements for feed-forward packet-switched communication networks. Researchers find it useful in analyzing network performance in real-time systems. As there are several Network Calculus tools and software packages for estimating network performance, it is important to select suitable Network Calculus tools for network analysis problems. This article introduces twelve established tools for Network Calculus analysis and compares their advantages and disadvantages in terms of their applicability for various systems and analysis needs. We also provide recommendations for users to select the suitable tools for research. Five public tools, namely DiscoDNC, RTC Toolbox, Deborah, CyNC, and nc-tandem-tight, are chosen to analyze end-to-end delay in a series of tandem networks for their performance demonstration. Simulations of the same tandem networks are implemented to compare with the analytical results achieved by the Network Calculus tools. To our best knowledge, this is the first comprehensive study that compares existing tools of Network Calculus analysis for real-time system network infrastructure. Our aim is to provide quick guidance to research communities for selecting suitable tools to analyze delay performance of networks.

Simulation modeling of packet switching network segment functioning

The testing results of required channel resource mathematical estimating models for the for serving the proposed multimedia load in packet-switched communication networks are presented in the article. The assessment of the attainable level of quality of service at the level of data packet transportation was carried out by means of simulation modeling of the functioning of a switching node of a communication network. The developed modeling algorithm differs from the existing ones by taking into account the introduced delay for processing each data stream packet arriving at the switching node, depending on the size of the reserved buffer and the channel resource for its maintenance. A joint examination of the probability of packet loss and the introduced delay in the processing of data packets in the border router allows a comprehensive assessment of the quality of service «end to end», which in turn allows you to get more accurate values of the effective data transmitted rate by aggregating flows at the entrance to the transport network.

Bandwidth Reduction and Convergence Analysis of Extremum Seeking Control with Feedback Encoding

Frequently a physical plant of a control system has an optimum operating point such as the spark (or injection) time of an internal combustion engine that results in maximum torque. Extremum Seeking Control (ESC) is a method of adaptive control capable of locating and maintaining a plant at such an optimum operating point in real time. It is capable of doing so with minimal a priori knowledge of the plant and can also track slowly varying changes. Input perturbed ESC schemes that use periodic dither signals have the disadvantage of requiring a high bandwidth for sampling and correlating the plant output with the dither signal. If the feedback path were to be implemented over a packet switched communication network, the high bandwidth requirement could result in increased congestion and consequently packet delays and dropouts. As a solution encoding using sporadic (aperiodic) sampling techniques can be used in the feedback path of the ESC scheme to reduce the required bandwidth. However, in order to ensure convergence of the ESC scheme with encoding, the effect of the signal reconstruction error due to encoding on the critical correlation stage has to be investigated. The contribution of this paper is an investigation of the convergence requirements and bandwidth performance of two encoding schemes; Memory Based Event Triggering (MBET) and Event Triggered Adaptive Differential Modulation (ETADM). The results show that MBET can fail for objective functions with plateaus. ETADM fails when the number of ETADM steps used for reconstructing the plant output per perturbation cycle are too low to allow correlation. In terms of bandwidth reduction MBET performs better than ETADM (97\% and 70\% respectively). However, the use of MBET results in a longer convergence time.

Analysis of overtaking in M/M/c queues

Overtaking events can occur in parallel processing systems when customers are served simultaneously by multiple servers. We say that one customer overtakes another when the customer leaves the system after having been served ahead of another customer(s) who arrived earlier. Overtaking events are an important issue in flexible assembly systems or packet switched communication networks. Although materials (or packets) can be processed by different servers simultaneously, there is a designated order for the assembly of final products (or data). If overtaking occurs, then additional time and money may be required to rearrange materials (or packets) to the original order (called resequencing). We investigate overtaking in an M/M/c queueing system. Two distributions were considered to describe the amount of overtaking: the number of customers that an arbitrary (tagged) customer overtakes and the number of customers who overtake the tagged customer. Explicit forms of these distributions are provided for some cases. Finally, we apply our results to practical issues in flexible assembly systems and telecommunication systems.

Stochastic adaptive event‐triggered control and network scheduling protocol co‐design for distributed networked systems

In a distributed ‘networked control system’ (NCS), multiple physical systems or agents are connected to their corresponding controllers through a shared packet-switched communication network. For such distributed NCS, periodic sampled controller design is unsuitable to handle packet-switched closed-loop control systems and a novel stochastic optimal adaptive event-sampled controller scheme is proposed in the application layer for each physical system or agent expressed as an uncertain linear dynamic system. Lyapunov stability analysis will be utilised to derive the event trigger condition. In addition, a network scheduling protocol is also required for such NCS. Traditional network scheduling protocols are unsuitable for such NCS since the behaviour of the physical systems is disregarded during the protocol design. Therefore in this study, a novel distributed network scheduling protocol via cross-layer approach is developed to improve the performance of distributed NCS by minimising an overall system cost function which consists of the information collected from both the event-triggered controller for each physical system in the application layer and the distributed scheduling protocol from the network layer. It will be demonstrated that the proposed co-design approach will not only allocate the network resources efficiently but also it will improve the performance of the overall distributed NCS. Simulation results are included to demonstrate the effectiveness of the proposed cross-layer co-design.

Convergence results for ant routing algorithms via stochastic approximation

In this article, we provide convergence results for an Ant-based Routing Algorithm (ARA) for wireline, packet-switched communication networks, that are acyclic. Such algorithms are inspired by the foraging behavior of ants in nature. We consider an ARA algorithm proposed earlier by Bean and Costa [2005]. The algorithm has the virtues of being adaptive and distributed, and can provide a multipath routing solution. We consider a scenario where there are multiple incoming data traffic streams that are to be routed to their respective destinations via the network. Ant packets, which are nothing but probe packets, are introduced to estimate the path delays in the network. The node routing tables, which consist of routing probabilities for the outgoing links, are updated based on these delay estimates. In contrast to the available analytical studies in the literature, the link delays in our model are stochastic, time-varying, and dependent on the link traffic. The evolution of the delay estimates and the routing probabilities are described by a set of stochastic iterative equations. In doing so, we take into account the distributed and asynchronous nature of the algorithm operation. Using methods from the theory of stochastic approximations, we show that the evolution of the delay estimates can be closely tracked by a deterministic ODE (Ordinary Differential Equation) system, when the step size of the delay estimation scheme is small. We study the equilibrium behavior of the ODE system in order to obtain the equilibrium behavior of the routing algorithm. We also explore properties of the equilibrium routing probabilities, and provide illustrative simulation results.

Analysis of finite-buffer state-dependent bulk queues

In this paper, we consider a general state-dependent finite-buffer bulk queue in which the rates and batch sizes of arrivals and services are allowed to depend on the number of customers in queue and service batch sizes. Such queueing systems have rich applications in manufacturing, service operations, computer and telecommunication systems. Interesting examples include batch oven processes in the aircraft and semiconductor industry; serving of passengers by elevators, shuttle buses, and ferries; and congestion control mechanisms to regulate transmission rates in packet-switched communication networks. We develop a unifying method to study the performance of this general class of finite-buffer state-dependent bulk queueing systems. For this purpose, we use semi-regenerative analysis to develop a numerically stable method for calculating the limiting probability distribution of the queue length process. Based on the limiting probabilities, we present various performance measures for evaluating admission control and batch service policies, such as the loss probability for an arriving group of customers and for individual customers within a group. We demonstrate our method by means of numerical examples.

Robust Rendezvous of Heterogeneous Euler-Lagrange Systems on Packet-Switched NetworksRobustes Rendezvous von heterogenen Euler-Lagrange Systemen mithilfe paketvermittelnder Netzwerke

Abstract A robust rendezvous controller design for multi-agent systems (MAS) is presented. The agents are modeled as Euler-Lagrange systems which exchange their position information on a packet-switched communication network, where the resulting communication delay is modeled in a distributed delay framework. A synthesis method for static position feedback controllers for these agents is proposed. It achieves rendezvous for uncertain communication delays with bounded average delay and for heterogeneous uncertain agent dynamics. The controllers only have to satisfy certain design conditions that relate sector bounds of the agent dynamics, Lipschitz bounds of the controllers, and the average communication delays of the network. A major advantage of the presented design condition is that the controller parameters depend only on the dynamics of the corresponding agent and the average communication delay to its neighbors, but not on the dynamics of the other agents or the delays in other parts of the network. This decentralized feature of the controller design is particularly useful for large and heterogeneous MAS. The performance of the controllers is illustrated by simulation.

Resilience Analysis of Packet-Switched Communication Networks

In the presence of local network outages, restoration and protection switching mechanisms redirect the traffic over alternative paths to mitigate the effect of failures. However, some failure combinations still lead to loss of ingress-egress connectivity within a network or to severe congestion due to rerouted traffic. Congestion may also be caused by unexpected traffic shifts due to changed user behavior or due to changes of interdomain routing. This paper presents a framework for the analysis of ingress-egress unavailability and link congestion due to: 1) failures; 2) changes of user behavior; and 3) changed interdomain routing. It proposes algorithms to find the most probable combinations of 1)-3) according to some models, and to evaluate the connectivity and the relative link load of the network under these conditions. We have implemented this concept in a software tool and its visualization of the results leads to a comprehensive view of the network's resilience. It helps to anticipate potential ingress-egress disconnection and congestion before failures and overload occur or before planned modifications (new infrastructure, new routing, new customers) take effect. Thus, it detects weak points in a network, predicts the effectiveness of potential upgrades, and thereby supports careful bandwidth overprovisioning.

Real-time available-bandwidth estimation using filtering and change detection

This paper presents a filter-based method BART (Bandwidth Available in Real-Time) for real-time estimation of end-to-end available bandwidth in packet-switched communication networks. BART relies on self-induced congestion, and repeatedly samples the available bandwidth of the network path with sequences of probe-packet pairs. The method is light-weight with respect to computation and memory requirements, and performs well when only a small amount of probe traffic is injected. BART uses Kalman filtering, which enables real-time estimation. It maintains a current estimate, which is incrementally improved with each new measurement of the inter-packet time separation in a sequence of probe-packet pairs. It is possible to tune BART according to specific needs. The estimation performance can be significantly enhanced by employing a change-detection technique. An implementation of BART has been evaluated in a physical test network with carefully controlled cross traffic. In addition, experiments have been performed over the Internet as well as over a mobile broadband connection.

An Optimal Distributed Routing Algorithm using Dual Decomposition Techniques

We consider the routing problem in wireline, packet-switched communication net- works. We cast our optimal routing problem in a multicommodity network flow optimization frame- work. Our cost function is related to the congestion in the network, and is a function of the flows on the links of the network. The optimization is over the set of flows in the links corresponding to the various destinations of the incoming traffic. We separately address the single commodity and the multicommodity versions of the routing problem. We consider the dual problems, and using dual decomposition techniques, we provide primal-dual algorithms that converge to the optimal solutions of the problems. Our algorithms, which are subgradient algorithms to solve the corresponding dual problems, can be implemented in a distributed manner by the nodes of the network. For online, adap- tive implementations of our algorithms, the nodes in the network need to utilize 'locally available information' like estimates of queue lengths on outgoing links. We show convergence to the optimal routing solutions for synchronous versions of the algorithms, with perfect (noiseless) estimates of the queueing delays. Every node of the network controls the flows on the outgoing links using the distributed algorithms. For both the single commodity and multicommodity cases, we show that our algorithm converges to a loop-free optimal solution. Our optimal solutions also have the attractive property of being multipath routing solutions. 1. Introduction. We consider in this paper the routing problem in wireline, packet-switched communication networks. Such a network can be represented by a directed graph G = (N , L), where N denotes the set of nodes and L the set of directed links of the network. For such a network we are given a set of origin-destination (OD) node pairs, with a certain incoming traffic rate (in packets per sec) associated with each OD pair. The arriving packets at the origin node have to be transported by the network to the corresponding destination node of the OD pair. The routing objective is to establish a packet traffic flow pattern so that packets are directed to their respective destinations while, at the same time, minimizing congestion in the network. A typical framework for accomplishing the same involves setting up an optimization problem, with the cost being related to the network-wide congestion and the constraints being the natural flow conservation relations in the network. For large-scale networks which are of interest to us, it is desired that the routing solution be implementable in a decentralized manner by the nodes of the network.

Compensation of position errors in passivity based teleoperation over packet switched communication networks

Because of the use of scattering based communication channels, passivity based telemanipulation systems can be subject to a steady state position error between master and slave robots. In this paper, we consider the case in which the passive master and slave sides communicate through a packet switched communication channel (e.g. Internet) and we provide a modification of the slave impedance controller for compensating the steady state position error arising in free motion because of packets loss.

An efficient dynamic resource allocation algorithm for packet-switched communication networks based on Hopfield neural excitation method

Dynamic Resource Allocation (DRA) algorithms set up different connections over the same resources and perform a scheduling policy to distribute the resources usage. Recently, intelligent DRA techniques based on Hopfield Neural Networks computational methods have been proposed, showing their potential for solving this kind of complex optimization problems. However, the initial algorithms suffer from severe instability problems impacting performance. This paper addresses these specific limitations stressing the proper neuron dynamics and proposing an efficient energy formulation and an optimum calculation of the weighting coefficients. These changes result in a maximum resource utilization together with an optimized neural network convergence.