Quality Of Service Analysis Research Articles

Analysis of QoS to Guarantee Application SLAs for Trusted Industrial Control Network

Differentiated services architecture is receiving wide attention as a framework for providing different levels of service in the industrial control networks.Traditional networks are designed with no traffic differentiation; all traffic mission-critical and non-mission-critical is treated equally.In indutrial networks, it becomes important to make sure that mission-critical applications do not suffer. QoS (Quality-of-Service) solutions, available in common network devices, try to provide traffic differentiation and predictable performance for mission critical applications.In this paper we propose a novel Quality of Service provisioning approach, appropriate for trusted industrial networks. This method, based on the real-time system reconfiguration, exploits the system monitoring information, along with quality parameters from the SLAs and experience from previous executions.The presented QoS provisioning process proposes a set of actions based on application specific policies, which are closely coupled with particular SLAs in order to provide the required QoS level for the application. Furthermore, We study applies the methodology using OPNET simulation products to compare and contrast the performance of a new application in an environment with and without IP QoS solutions.

QoS Analysis of a Distributed System Considering the Processing Time

In this paper, we introduce Quality of Service(QoS) analytic model of a distributed system that decentralizes the process nodes performing each task and communicates through a network for cooperation. The model advances a service reliability model of Dai et a1.(2003) by means of considering the processing time. The service is assumed to be provided by a centralized heterogeneous distributed system which is composed of some subsystems managed by a control center. The QoS is defined as the probability that a service is provided successfully in an allowed time, we consider the hardware/software reliability and the processing time which include program execution time, data transfer time. We derive the processing time distribution for a required service through convolution of corresponding probability density function. An application example is used to explain the procedure of computing quality of service.

A distributed channel assignment control for QoS support in mobile ad hoc networks

Recently, one of the most critical issues in mobile ad hoc networks (MANETs) is providing quality of service (QoS) through routing, access/admission control, resource reservation, and mobility management. However, most existing solutions do not provide QoS effectively due to the interference arising from mobility. In this paper, we refer to interference as a quasi-exposed node problem. To solve this problem, a new algorithm, named a distributed channel assignment control, is proposed that focuses on performance enhancements related to QoS and mathematical analysis techniques for the channel bandwidth. This novel algorithm uses channel assignment control with a power control to reduce the negative effects induced by the quasi-exposed node problem, and then the channels are adaptively negotiated to allow communication in the interference region. The proposed algorithm has been evaluated via extensive simulations, and the results show that it can successfully guarantee QoS by maintaining good throughput, reducing control message overhead, and enhancing delay.

Approximation Method for QoS Analysis of Wireless Cellular Networks with Impatient Calls

Simple-closed expressions for approximate calculation of quality of service (QoS) metrics of isolated cell of wireless networks with either finite or infinite queues of both new and handover calls are developed. It is assumed that both kinds of calls might leave the system without receiving service if their waiting times exceed some threshold value. For the models with infinite queues of heterogeneous calls easily checkable ergodicity conditions are proposed. The high accuracy of the developed approximation formulas is shown. Results of numerical experiments are given.

QoS Analysis of a Scheduling Policy for Heterogeneous Users Employing AMC Jointly with ARQ

This paper analyzes the quality of service (QoS) of scheduling algorithms for heterogeneous users in multi-user (MU) wireless systems that take advantage from a cross-layer design with both adaptive modulation and coding (AMC) and automatic repeat request (ARQ). By developing a general theoretical framework based on a finite-state Markov chain, we analytically evaluate the average delay, the packet-loss rate (PLR) and the throughput of a scheduling algorithm based on the channel condition, the buffer occupancy, and the number of retransmissions, of users belonging to different service classes. The key assumption of our analysis, i.e., the independence of the stationary states of different users, highly reduces the computational complexity while preserving a sufficient accuracy. To present the proposed analysis, we also suggest an effective scheduling policy suitable for users belonging to different service classes, compliant with the WiMAX standard. The good match between analytical and simulated performance validates our theoretical findings, and enables the proposed approach to be used for cross-layer optimization.

A New Queueing Model for QoS Analysis of IEEE 802.11 DCF with Finite Buffer and Load

Quality of Service (QoS) and queue management are important issues for IEEE 802.11 systems. However, existing 2-dimensional (2-D) Markov chain models of 802.11 systems are unable to capture the complete QoS performance and queueing behavior due to the lack of an adequate finite buffer model. We present a 3-dimensional (3-D) Markov chain that integrates the 802.11 system contention resolution and queueing processes into one model. The 3rd dimension, that models the queue length, allows us to accurately capture important QoS measures, delay and loss, plus throughput and queue length, for realistic 802.11 systems with finite buffer under finite load. We derive an efficient method for solving the steady state probabilities of the Markov chain. Our 3-D Markov chain is the first finite buffer model defined and solved for 802.11 systems. The solutions, validated by extensive simulations, capture the system dynamics over a wide range of traffic load, buffer capacity, and network size. Our 3-D model points to the existence of an effective maximum throughput and shows its relationship with buffer capacity. We demonstrate that our 3-D model can also be used in resource allocation to determine adequate buffer sizes under a particular QoS constraint.

Cross-Layer Analysis of the End-to-End Delay Distribution in Wireless Sensor Networks

Emerging applications of wireless sensor networks (WSNs) require real-time quality-of-service (QoS) guarantees to be provided by the network. Due to the nondeterministic impacts of the wireless channel and queuing mechanisms, probabilistic analysis of QoS is essential. One important metric of QoS in WSNs is the probability distribution of the end-to-end delay. Compared to other widely used delay performance metrics such as the mean delay, delay variance, and worst-case delay, the delay distribution can be used to obtain the probability to meet a specific deadline for QoS-based communication in WSNs. To investigate the end-to-end delay distribution, in this paper, a comprehensive cross-layer analysis framework, which employs a stochastic queueing model in realistic channel environments, is developed. This framework is generic and can be parameterized for a wide variety of MAC protocols and routing protocols. Case studies with the CSMA/CA MAC protocol and an anycast protocol are conducted to illustrate how the developed framework can analytically predict the distribution of the end-to-end delay. Extensive test-bed experiments and simulations are performed to validate the accuracy of the framework for both deterministic and random deployments. Moreover, the effects of various network parameters on the distribution of end-to-end delay are investigated through the developed framework. To the best of our knowledge, this is the first work that provides a generic, probabilistic cross-layer analysis of end-to-end delay in WSNs.

Subjective QoE analysis of VoIP applications in a wireless campus environment

The quality perceived by the user, a concept known as Quality of user Experience (QoE), is gaining momentum. Together with the efforts of providing appropriate architectures able to deliver the expected level of Quality of Service (QoS), users' perception of the level of quality could play a key role in making a VoIP multimedia application to succeed or to fail. QoE can be measured from different approaches; subjective ones are based on polls while objective ones are mainly based on QoS network performance parameters. Although a subjective evaluation could be costly and time consuming, it gives the most accurate results. Moreover, wireless environments incorporate new challenges in terms of QoS and QoE because of inherent wireless communication characteristics. In this way, our contribution is twofold. First, we carry out a subjective QoE assessment for VoIP applications in a real wireless environment. Skype, Gizmo5, ooVoo, and Damaka are the selected VoIP applications under study. Next, we contrast QoE results with QoS evaluation from the captured video calls made during the poll. Results show that there is no precise match on both assessments, because of QoE parameters that cannot be inferred from QoS analysis, because of the different effect of some QoS parameters which prevail, or even because of the popularity of the VoIP application.

QoS analysis of medium access control in LR-WPANs under bursty error channels

Low Rate Wireless Personal Areas Networks (LR-WPANs) have been widely deployed for the purpose of short range, low rate, and low power wireless networking. The IEEE 802.15.4 standard defines a Medium Access Control (MAC) layer protocol for LR-WPANs. The analytical models reported in the literature for 802.15.4 MAC have been mainly developed under the assumptions of ideal channels or uniform error channels, which fail to capture the characteristics of bursty and correlated channel errors in a practical wireless network environment. In this paper, we present an analytical model for 802.15.4 MAC in LR-WPANs in the presence of bursty error channels. This model can be used to obtain the Quality-of-Service (QoS) performance metrics, including throughput, service time, and frame delay. The accuracy of the model is validated through NS-2 simulation experiments. Utilizing the analytical model, we investigate the QoS performance of 802.15.4 MAC under various traffic loads, backoff parameters, numbers of nodes, and channel conditions. The analytical model is demonstrated to be a cost-effective tool for evaluating the QoS performance of 802.15.4 MAC in the presence of bursty error channels.

Energy consumption and message delay analysis of QoS enhanced base station controlled dynamic clustering protocol for wireless sensor networks

This paper proposes and analyzes a Quality of service enhanced Base station Controlled Dynamic Clustering Protocol (QBCDCP), suitable for the support of video and imaging traffic over resource constrained wireless sensor nodes. The protocol achieves energy efficiency through a rotating head clustering approach and delegation of energy-intensive tasks to a high-power base station, while providing quality of service (QoS) support by including delay and bandwidth parameters in the route selection process. A Time Division Multiple Access (TDMA) scheme is used for intra- and intercluster communication, providing bandwidth reservation. Performance of QBCDCP is evaluated in terms of energy consumption and end-to-end image delay via analytical and discrete-event simulation techniques. Numerical results provide insights on the selection of network parameters such as number of clusters that improve the sensing node lifetime while maintaining high quality of service. The results also demonstrate the trade-off between end-to-end image delay and sensor node lifetime.

QoS Perceived by Users of Ubiquitous UMTS: Compositional Models and Thorough Analysis

.This paper provides a QoS analysis of a dynamic, ubiquitous UMTS network scenario in the automotive context identi_ed in the ongoing EC HIDENETS project. The scenario comprises different types of mobile users, applications, traffic conditions, and outage events reducing the available network resources. Adopting a compositional modeling approach based on Stochastic Activity Networks (SAN) formalism, we analyze the Quality of Service (QoS) both from the users' perspective and from the mobile operator's one. The classical QoS analysis is enhanced by taking into account the congestion both caused by the outage events and by the varying traffic conditions. The impact of users' mobility on the selected QoS indicators is further investigated combining the SAN modelling approach with an ad-hoc mobility simulator, which also allows to re_ne the model representing the UMTS network behavior.

Analysis of QoS in cooperative services for real time applications

Future complex architectures for Web-Services-based delivery of services and objects require applications able to deal with different levels of Quality of Service (QoS) and able to describe also the quality of the associated object. In order to allow applications adapting in front of degraded quality in a pre-determined way, all the nodes participating in a given business process shall coordinate their efforts in (i) deciding how to deal with service degradation/disruption, and in (ii) managing the overall quality (i.e., not only the Web-Service QoS but also the quality of the objects being delivered through the cooperative process). According to this rationale, one of the main goals of the Quadrantis project has been to investigate how to provide combined quality measurement of services and delivered objects, such as videos, voice, texts, or images. QoS modelling and management according to users’ needs are presented. Users will access services according to QoS Contracts negotiated with service providers, while the streaming content is based on user profiles, to face a more dynamic management of QoS deviations in the Real Time provisioning level. In our approach, applications can request QoS, and react and repair to violations of the terms set forth in contracts or in expected delivery parameters, such as bandwidth or frame rate. To this extent, we present a framework for providing applications and services with QoS adaptation functionality, through the step-wise induction of a monitoring and recovery solutions at both Web-Services and streaming layers. The foundations of the merging between the two layers, which deal with very different aspects and protocols, are based on quality.

Quantitative analysis of location management and QoS in wireless networks

As a fundamental component in wireless networks, location management consists of two operations: location update and paging. These two supplementary operations enable the mobile user ubiquitous mobility. However, in case of failed location update, a significant consequence is the obsolete location identity in the network databases and thereafter the incapability in establishing the valid route for the potential call connection, which will seriously degrade the network quality-of-service (QoS). This issue is not theoretically studied in the literature. In this paper, we perform a quantitative analysis of the location management effect on QoS in the wireless networks. The metrics call blocking probability and the average number of blocked calls are introduced to reflect the QoS. For the sake of general applicability, the performance metrics are formulated with the relaxed tele-traffic parameters. Namely, the call inter-arrival time, cell residence time, location area residence time and location update inter-arrival time follow a general probability density function. The formulae are additionally specified in the static and several dynamic location management mechanisms. Numerical examples are presented to show the interaction between the performance metrics and location management schemes. The discussions on the sensitivity of tele-parameters are also given.

Analysis of QoS for DVB‐RCS‐based IP network

PurposeThe internet has been used to transport data in the form of packet. Multimedia applications including voice and video are being sent using the internet. In the past, the internet did not support any kind of sophisticated quality of service (QoS) mechanism. Although the type of service (ToS) field in the internet protocol (IP) header has been present and allowed the differentiated treatment of packets, it was never really used on a large‐scale. IP applications have been mostly used on terrestrial networks so far. This paper aims to describe the architecture of a DVB‐RCS based satellite network supporting interactive and multimedia applications.Design/methodology/apporachThe use of TCP/IP has made it possible to have two way communication using open standard satellite networks based on digital video broadcast return channel via satellite (DVB‐RCS). The voice and video are sensitive to delay and jitter so bandwidth must be guaranteed while transporting it. With the extensive use of IP for carrying voice and video, there is a need to add QoS functionality in satellite networks. The performance of data transfer using voice and video with reference to QoS parameters in satellite network is analyzed in this paper.FindingsThe results show that satellite networks based on DVB‐RCS can carry voice and video traffic and offer good quality of service in terms of packet loss and jitter but are poor in quality in terms of packet delay.Originality/valueThis paper describes the architecture of a DVB‐RCS based satellite network supporting interactive and multimedia applications.

QoS modeling and analysis of component‐based software systems: a stochastic approach

AbstractThere is a growing demand for using commercial‐off‐the‐shelf (COTS) software components to facilitate the development of software systems. Among many research topics for component‐based software, quality‐of‐service (QoS) evaluation is yet to be given the importance it deserves. In this paper, we propose a novel analytical model to evaluate the QoS of component‐based software systems. We use the component execution graph (CEG) graph model to model the architecture at the process level and the interdependence among components. The CEG graph can explicitly capture sequential, parallel, selective and iterative compositions of components. For QoS estimation, each component in the CEG model is associated with execution rate, failure rate and cost per unit time. Three metrics of the QoS are considered and analytically calculated, namely make‐span, reliability and cost. Through a case study, we show that our model is capable of modeling real‐world COTS software systems effectively. Also, Monte‐Carlo simulation in the case study indicates that analytical results are consistent with simulation and all are covered by 95% confidence intervals. We also present a sensitivity analysis technique to identify QoS bottlenecks. This paper concludes with a comparison with related work. Copyright © 2007 John Wiley & Sons, Ltd.

Cross-layer QoS Analysis of Opportunistic OFDM-TDMA and OFDMA Networks

Performance analysis of multiuser orthogonal frequency division multiplexing (OFDM-TDMA) and orthogonal frequency division multiple access (OFDMA) networks in support of multimedia transmission is conducted in this work. We take a cross-layer approach and analyze several quality-of-service (QoS) measures that incilude the bit rate and the bit error rate (BER) in the physical layer, and packet average throughput/delay and packet maximum delay in the link layer. The authors adopt a cross-layer QoS framework similar to that in IEEE 802.16, where service classification, flow control and opportunistic scheduling with different subcarrier/bit allocation schemes are implemented. In the analysis, the Rayleigh fading channel in the link layer is modeled by a finite-state Markov chain, and the channel state information (CSI) is assumed to be available at the base station. With the M/G/1 queueing model and flow control results, the analysis provides important insights into the performance difference of these two multiaccess systems. The derived analytical results are verified by extensive computer simulation. It is demonstrated by analysis and simulation that OFDMA outperforms OFDM-TDMA in QoS metrics of interest. Thus, OFDMA has higher potential than OFDM-TDMA in supporting multimedia services.

Service-level agreement-based QoS analysis for web services discovery and composition

Quality-of-Service (QoS) in Web services considers a service's non- functional characteristics during service specification, discovery, and composition. In order to encourage the development of QoS-aware Web services, we first develop a QoS-aware model, which contains a common set of QoS attributes including response time, throughput, reliability, availability and price etc. Then, based on the attributes, two alternative service selection methods, namely absolute and relative matchmaking, are presented. Finally, according to the formal semantics of different workflow patterns, we utilize the aggregative effects of QoS attributes to help service consumers perform QoS-aware service composition.

A formal approach to the integrated analysis of security and QoS

Concurrent and distributed systems are subject to several requirements of different nature. Among them security and quality of service (QoS) are two fundamental aspects, which can have a profound impact on the system performability. Unfortunately, the study of the tradeoff between security guarantees and performance needs is hard to accomplish, because the related analysis activities are usually carried out separately. In this paper, we present an integrated and tool-supported methodology encompassing both activities, which can provide insights about how to trade the QoS delivered by a system with its security guarantees. The methodology is illustrated by assessing the effectiveness and the efficiency of the securing strategy implemented in the NRL Pump, a trusted device proposed to secure the replication of information from a low-security level enclave to a high-security level enclave.

A calculus for stochastic QoS analysis

The issue of Quality of Service (QoS) performance analysis in packet-switched networks has drawn a lot of attention in the networking community. There is a lot of work including an elegant theory under the name of network calculus, which focuses on analysis of deterministic worst case QoS performance bounds. In the meantime, researchers have studied stochastic QoS performance for specific schedulers. However, most previous works on deterministic QoS analysis or stochastic QoS analysis have only considered a server that provides deterministic service, i.e. deterministically bounded rate service. Few have considered the behavior of a stochastic server that provides input flows with variable rate service, for example wireless links. In this paper, we propose a stochastic network calculus to analyze the end-to-end stochastic QoS performance of a system with stochastically bounded input traffic over a series of deterministic and stochastic servers. We also prove that a server serving an aggregate of flows can be regarded as a stochastic server for individual flows within the aggregate. Based on this, the proposed framework is further applied to analyze per-flow stochastic QoS performance under aggregate scheduling.

QoS analysis for component-based embedded software: Model and methodology

Component-based development (CBD) techniques have been widely used to enhance the productivity and reduce the cost for software systems development. However, applying CBD techniques to embedded software development faces additional challenges. For embedded systems, it is crucial to consider the quality of service (QoS) attributes, such as timeliness, memory limitations, output precision, and battery constraints. Frequently, multiple components implementing the same functionality with different QoS properties (measurements in terms of QoS attributes) can be used to compose a system. Also, software components may have parameters that can be configured to satisfy different QoS requirements. Composition analysis, which is used to determine the most suitable component selections and parameter settings to best satisfy the system QoS requirement, is very important in embedded software development process. In this paper, we present a model and the methodologies to facilitate composition analysis. We define QoS requirements as constraints and objectives. Composition analysis is performed based on the QoS properties and requirements to find solutions (component selections and parameter settings) that can optimize the QoS objectives while satisfying the QoS constraints. We use a multi-objective concept to model the composition analysis problem and use an evolutionary algorithm to determine the Pareto-optimal solutions efficiently.