Quality Of Service Assessment Research Articles

Evaluation of Quality of Service in 4th Generation (4G) Long Term Evolution (LTE) Cellular Data Networks

The area of study proposed in this paper is the evaluation of the Quality of Service (QoS) provided by a Long Term Evolution (LTE) cellular data network. It is aimed to address the gap between the technical capabilities and the QoS experienced by the user. The analysis is based on the live data that are collected on commercial cellular network and compared against broadband wireless LAN. A methodology for QoS assessment based on a relatively small set of Key Performance Indicators (KPIs) is devised. The measured data are used to verify the proposed methodology.

A Review of Recent Patents for Quality Assessment of Multimedia Communications by Digital Watermarking

Multimedia communication has gained an increasing interest in the last decade. The design of services and distributed multimedia applications imposes a number of Quality of Service (QoS) requirements. In particular, the processing and delivery of multimedia content are not independent and their interaction has a major impact on the QoS aspects. Recently, tracing watermarking has been introduced as a blind method for evaluating the QoS of multimedia communications. This paper aims at presenting a review of recent patents, and state of art solutions as well, in the field of QoS assessment of multimedia communication by tracing watermarking. Finally, a discussion pointing out the current and future developments in this area summarizes the remarkable points of this work.

Context-Aware Service Ranking in Wireless Sensor Networks

Wireless sensor networks (WSNs) are widely used in practice for comprehensively monitoring and gathering physical information via a multitude of sensors. As the development of WSNs, the integration of them with the external Internet is a urgent need. By wrapping the sensor functionality as a WSN service, the Web service is considered as the most promising technology to incorporate WSNs into the Internet. The quest for selecting the service with the best performance promotes service ranking technology. However, due to the dynamic WSN environment, traditional quality of service (QoS) based ranking approaches for general Web services are no longer suitable for the WSN service. In this article, in order to fit the characteristics of the WSN environment, we propose a context-aware WSN service ranking approach by aggregating the user rating and WSN service context. First, the User QoS Assessment(UQA) and Context QoS Assessment(CQA) are proposed, respectively. Then, through the performance influence on the WSN service by the variations in their context, a Fuzzy mechanism is further developed to aggregate the UQA and the CQA. Finally, the experiments are presented to confirm the validity of the proposed approach.

Watermarking-Based Blind QoS Assessment for Wireless Image Communication

This paper presents a novel scheme to blindly estimate the quality of an image communication link by means of an unconventional use of digital watermarking. The watermarking technique is usually employed for digital media copyright protection and authenticity verification. However, watermarking is here adopted as a method to provide a blind assessment of the quality of service (QoS) in wireless image communication. First, a compressed-domain watermarking scheme is proposed. Each 8×8 block in a JPEG compressed image is first processed by entropy decoding, and then the parity of the number of non-zero alternating current (AC) coefficients in each quantized discrete cosine transform (DCT) block is modified to embed the watermark. Second, the performances of the proposed watermarking scheme have been tested. Finally, the proposed watermarking scheme is applied to estimate the QoS of an image communication link based on the assessment factor which is associated with the errors between the extracted watermark and the original. Experimental results show the proposed scheme can evaluate the QoS of wireless image communication channels exactly without increasing the bit rate transmission. Moreover, the quality of the carrier image has not been affected. 

Stochastic Model for QoS Assessment in Multi-tier Web Services

Service Level Agreements (SLAs) are used to guarantee quality of service (QoS) between customers and service providers. In an SLA, parties establish a common set of rules and responsibilities. In this paper we propose a practical stochastic modeling of a multi-tier architecture considering SLAs for specific transactions. The model is parameterized with available performance testing data for a real web service, and with a testing environment having unpredictable and unknown external workloads of simultaneous execution. In addition, we present multiple scenarios of external applications impacting on the SLAs in our target architecture. Having a previous knowledge about the average time demanded by some external applications, our model results can provide evidences when the system under test will not respect the agreed-upon SLAs. Finally, we discuss possible model extensions towards further unknown workload characterizations and considerations about application execution profiling.

Quality of service assessment of opportunistic spectrum access: a medium access control approach

Opportunistic spectrum access (OSA) is a promising new spectrum management approach that will allow coexistence of both licensed and opportunistic users in each spectrum band, potentially decreasing the spectrum licensing costs for both classes of users. However, this has significant implications on the QoS experienced by the licensed and opportunistic spectrum users. In this article we investigate how tolerant to secondary user activity a licensed user should be so as to provide dependable communication with sufficient QoS to an opportunistic user. We also look at key multichannel MAC features for such OSA networks proposed in the literature, and discuss how the design of control channel management affects the QoS of opportunistic users as a function of the tolerance of licensed users. We quantify the trade-off between dependability of the OSA network and the dependability of licensed users. The main conclusion is that opportunistic users can indeed achieve good QoS, as long as the licensed users are not highly active. For example, in one of the scenarios we studied, opportunistic users can achieve a delay below 100 ms if licensed user activity stays below 30 percent.

Wireless industrial sensor networks: Framework for QoS assessment and QoS management

Abstract This paper presents a framework that addresses Quality of Service (QoS) for industrial wireless sensor networks as a real-time measurable set of parameters within the context of feedback control, thereby facilitating QoS management. This framework is based on examining the interaction between the industrial control processes and the wireless network. Control theory is used to evaluate the impact of the control/communication interaction, providing a methodology for defining, measuring, and quantifying QoS requirements. An example is presented illustrating the wireless industrial sensor network (WISN) QoS management framework for providing dynamic QoS control within WISN. The example focuses on WISN operating in a time-varying RF interference environment in order to manage application-driven QoS latency constraints.

QoS assessment via stochastic analysis

Using a stochastic modeling approach based on the Unified Modeling Language and enriched with annotations that conform to the UML profile for schedulability performance, and time, the authors propose a method for assessing quality of service (QoS) in fault-tolerant (FT) distributed systems. From the UML system specification, they produce a generalized stochastic Petri net (GSPN) performance model for assessing an FT application's QoS via stochastic analysis. The ArgoSPE tool provides support for the proposed technique, helping to automatically produce the GSPN model

Expectation-based quality of service assessment

The ability to gauge quality of service is critical if we are to realise the potential of the service-oriented computing paradigm. Many techniques have been proposed for calculating the quality of a service, and they do so typically by collecting quality ratings from the users of the service, then combining them in one way or another to derive the quality of the service. We argue that collecting quality ratings alone from the users is not sufficient for deriving a reliable and accurate quality measure for a service. This is because different users often have different expectations on the quality of a service and their ratings tend to be closely related to these expectations, i.e. how their expectations are met. In this paper, we propose a quality of service assessment model based on user expectations. That is, we collect expectations as well as ratings from the users of a service, then calculate the quality of the service using only the ratings that have similar expectations. Our experiments show that the method we propose here can result in more meaningful and reliable quality ratings for services.

Multimedia Quality Prediction Methodologies for Advanced Mobile and IP-Based Telephony

This paper describes the author's perspective on multimedia quality prediction methodologies for multimedia communications in advanced mobile and internet protocol (IP)-based telephony, and reports related experiments and trials. First, the paper describes the need for perceptual QOS (Quality of Service) assessment in which various quality factors in multimedia communications for advanced mobile and IP-based telephony are analyzed. Then an objective quality prediction scheme is proposed from the viewpoints of quality measurement tools for each quality factor and an opinion model for compound quality factors in mobile and IP-based communications networks. Finally, the author's current trials of measurement tools and opinion models are described.

Quantitative assessment of user-level QoS and its mapping

This paper proposes a scheme for quantitative assessment of user-level (or perceptual) quality of service (QoS) for audio-video transmission by means of two psychometric methods: the method of paired comparisons and the law of comparative judgment. Moreover, we discuss QoS mapping from application-level QoS to user-level QoS by principal component analysis and multiple regression analysis. In the assessment, we simulate the transmission of an audio-video stream over a loaded network. In order to investigate the effect of the contents on QoS mapping, we treat two types of audio-video streams. By experiment, we demonstrate that our scheme can construct an interval scale as the user-level QoS parameter for each stream and represent it as a function of two application-level QoS parameters with high accuracy. We notice that the multiple regression line depends on the contents. We also propose the concept of control gain by media synchronization, which indicates how much media synchronization control subjectively lightens the average network load.

Engset multi-rate state-dependent loss models

Call blocking probabilities (CBP) are a key index of quality of service assessment in multi-rate networks. We focus on the CBP calculation in single link loss models where calls of each service-cla...

QoS assessment of video streams over IP networks based on monitoring transport and application layer processes at user clients

A method of assessing the quality of service (QoS) of TCP/IP-based video streams for real environments is proposed. To investigate the cause of video quality degradation and to observe the video QoS level at user clients, a method for monitoring the QoS-related parameters in both the transport and application layers for the target system is employed. To detect the cause of QoS degradation, the authors focus on the number of packet retransmissions and the transmission delay of packets observed in the transport layer. Also, for measuring the QoS level, the bit rate of video streams and buffer usage rates in the application layer are the focus. Based on measurement using an MPEG-4 video system in a real environment, it is confirmed that the buffer usage rate in the application layer tended to decrease before the detection of sudden decreases in the bit rate of video streams, and that underflow events where the buffer usage rate dropped to less than 30-50% tended to cause QoS deterioration of video applications. The proposed method deals with QoS-related parameters for TCP/IP-based video streams so it is possible to efficiently check the reasons for and the patterns of the QoS degradation.

Connection-dependent threshold model: a generalization of the Erlang multiple rate loss model

In this paper first, we review two extensions of the Erlang multi-rate loss model (EMLM), whereby we can assess the call-level quality-of-service (QoS) of ATM networks. The call-level QoS assessment in ATM networks remains an open issue, due to the emerged elastic services. We consider the coexistence of ABR service with QoS guarantee services in a VP link and evaluate the call blocking probability (CBP), based on the EMLM extensions. In the first extension, the retry models, blocked calls can retry with reduced resource requirements and increased arbitrary mean residency requirements. In the second extension, the threshold models, for blocking avoidance, calls can attempt to connect with other than the initial resource and residency requirements which are state dependent. Secondly, we propose the connection-dependent threshold model (CDTM), which resembles the threshold models, but the state dependency is individualized among call-connections. The proposed CDTM not only generalizes the existing threshold models but also covers the EMLM and the retry models by selecting properly the threshold parameters. Thirdly, we provide formulas for CBP calculation that incorporate bandwidth/trunk reservation schemes, whereby we can balance the grade-of-service among the service-classes. Finally, we investigate the effectiveness of the models applicability on ABR service at call set-up. The retry models can hardly model the behavior of ABR service, while the threshold models perform better than the retry models. The CDTM performs much better than the threshold models; therefore we propose it for assessing the call-level performance of ABR service. We evaluate the above-mentioned models by comparing each other according to the resultant CBP in ATM networks. For the models validation, results obtained by the analytical models are compared with simulation results.