Vol. 65, n° 1-2, January-February 2014
Content available on Springerlink

Guest editors
Markus Fiedler, Blekinge Institute of Technology, Sweden
Helmut Hlavacs, University of Vienna, Austria
Klaus Hackbarth, University of Cantabria, Spain
Patrik Arlos, Blekinge Institute of Techology, Sweden

Foreword 

Markus Fiedler, Helmut Hlavacs, Klaus Hackbarth, Patrick Arlos

Automated qualitative assessment of multi-modal distortions in digital images based on GLZ

Andrzej Głowacz¹ · Michał Grega¹ · Przemysław Gwiazda²· Lucjan Janowski¹ · Mikołaj Leszczu¹ · Piotr Romaniak¹ · Simon Pietro Romano<sup>3

1</sup> Department of Telecommunications, AGH University of Science and Technology, Krakow, Poland
² Telekomunikacja Polska R&D, Warsaw, Poland
³ Computer Science Department, Universita’ degli Studi di Napoli Federico II, Naples, Italy

Abstract This paper introduces a novel approach to a qualitative assessment of images affected by multimodal distortions. The idea is to assess the image quality perceived by an end user in an automatic way in order to avoid the usual time-consuming, costly and non-repeatable method of collecting subjective scores during a psycho-physical experiment. This is achieved by computing quantitative image distortions and mapping results on qualitative scores. Useful mapping models have been proposed and constructed using the generalised linear model (GLZ), which is a generalisation of the least squares regression in statistics for ordinal data. Overall qualitative image distortion is computed based on partial quantitative distortions from component algorithms operating on specified image features. Seven such algorithms are applied to successfully analyse the seven image distortions in relation to the original image.Asurvey of over 12,000 subjective quality scores has been carried out in order to determine the influence of these features on the perceived image quality. The results of quantitative assessments are mapped on the surveyed scores to obtain an overall quality score of the image. The proposed model  have been validated in order to prove that the above technique can be applied to automatic image quality assessment.

Keywords Image quality · Image distortion · MOS · Mean opinion score · GLZ · Generalised linear models · Quality metrics

An integrated framework of HoQ & AHP for QoE improvement of network-based ASP services

Dohoon Kim

College of Business Administration, Kyung Hee University

Abstract The ASP (Application Service Provider) industry provides an essential infrastructure for Internetbased e-business transactions. First, we introduce the HoQ (House of Quality) framework, which provides the best way to not only arrange and evaluate VoC (Voice of Customers) and VoE (Voice of Engineers) but also combine VoC and VoE, thereby presenting explicit directions for QoE (Quality of Experience) enhancement. However, there have been few studies on HoQ for developing and improving telecom services. Here, we employ the AHP (Analytical Hierarchy Process) method to evaluate VoC, VoE, and their relationships so that qualitative measurement, which is the weakest point of the traditional HoQ approach, can be substituted by quantitative and interactive estimation. The case study discussed here serves as an illustration of the applicability and usefulness of the integrated HoQ/AHP approach to the ASP industry. The proposed integrated framework successfully finds key functional elements, such as business customization and security/failure management, to reengineer the service delivery process, thereby helping service providers develop better ASP services to improve QoE effectively and efficiently.

Keywords: Quality of Service (QoS), Quality of Experience (QoE), Voice of Customer (VoC), Voice of Engineer (VoE), House of Quality (HoQ), Analytical Hierarchical Process (AHP), Application Service Provider (ASP), IT Service Quality, Service Delivery Process Reengineering

Optimal Server Bandwidth for Mobile Video on Demand

Shelley Buchinger · Helmut Hlavacs

Institute of Distributed and Multimedia Systems Faculty of Computer Science, University of Vienna, Austria

Abstract Multimedia services such as video-on-demand or IPTV in mobile environments established themselves in our daily lives, yet the obtained Quality of Service still leads to many open issues. One of them consists in minimizing the server bandwidth, and we recently proposed a novel patching scheme for transporting true video-on-demand called Hierarchical Patching whichminimizes the server bandwidth. In this paper we present a new concept called Low Start, consisting of encoding the first part of a movie with a lower bitrate than the rest. In Hierarchical Patching, video parts at the beginning have a much higher probability to be transmitted than parts at the end. By using Low Start we show that the overall server bandwidth can be drastically reduced. We furthermore investigate the impact of Low Start on the subjective QoS as perceived by human observers, and show that for mobile video the optimal strategy is to encode a very short start time with a bandwidth as low as possible.

Keywords Batching · server bandwidth · true video-ondemand · video patching

Quality of Experience from user and network perspectives

Junaid Shaikh¹ · Markus Fiedler¹ · Denis Collange²

¹ Blekinge Institute of Technology, Karlskrona, Sweden
² Orange Labs, Sophia-Antipolis, France

Abstract The impact of network performance on user experience is important to know, as it determines the success or failure of a service. Unfortunately, it is very difficult to assess it in real-time on an operational network. Monitoring of network-level performance criteria is easier and more usual. But the problem is then to correlate these network-level Quality of Service (QoS) to the Quality of Experience (QoE) perceived by the users. Efforts have been done in the previous years to map user behaviour to traffic characteristics on the network to QoS. However, being able to successfully relate these traffic characteristics to user satisfaction is not a simple task and still requires further investigations. In this work, we try to associate on one side the correlations between various traffic characteristics measured on an operational network and on the other side the user experience tested on an experimental platform. Our aim is to observe some pronounced trends regarding relationships between both types of results. More precisely, we want to validate how and to what extent the volumes of user sessions represent the level of user satisfaction. Along this way, we need to revise classical relationships between some of the network performance indicators such as loss, download time and throughput in order to strengthen the understanding of this impact on each other and on user satisfaction. This preliminary study is based on the application web.

Keywords Quality of Experience . Quality of Service . Traffic analysis . Passive measurements . Opinion Score

On the fairness characteristics of FAST TCP

Tuan A. Trinh · Balázs Sonkoly · Sándor Molnár

Department of Telecommunications and Media Informatics, Budapest University of Technology and Economics, Budapest, Hungary

Abstract Fairness of competing transmission control protocol (TCP) flows is an integral and indispensable part of transport protocol design for next-generation, high-bandwidth-delay product networks. It is not just a protocol-intrinsic property but it could also have severe impact on quality of experience (QoE). In this paper, we revisit FAST TCP fairness behavior based on a comprehensive performance evaluation study. We demonstrate that FAST TCP with proper parameter settings can always achieve fair behavior with HighSpeed TCP and Scalable TCP. We also show that this behavior is a rather robust property of the protocol concerning different traffic mix or network topology. The dynamic behavior of reaching the fair equilibrium state can be different, which is demonstrated in the paper. Our study also emphasizes the important need for finding a dynamic sensitive fairness metric for performance evaluation of transport protocols for next-generation, high-bandwidth-delay product networks.

Keywords High-speed networks · FAST TCP · Fairness analysis

Towards real-time anomalies monitoring for QoE indicators

Frédéric Guyard · Sergio Beker

 FTRD/Orange Labs, Sophia-Antipolis, France

Abstract Anomaly detection and characterization is a main topic for network managers. Although qualityof- service (QoS) indicators can help to infer problem occurrence, they do not provide immediate insight on the user’s perceived quality. Evolved service-level agreements (SLA) will likely be established in terms of quality of experience (QoE) indicators. QoS metrics composing the QoE indicators need to be monitored on a real-time basis by the SLA management tools in order to detect anomalies driving to contract violations. Monitoring SLA contracts may involve the surveillance of individual application sessions for several users. In this work, we address the problem of anomaly detection with impact on a relatively large number of users, either on one or on several types of applications simultaneously. We propose a method to characterize the state of the network, representingQoE indicators as time series and reducing the dimension of the data set. The singular spectrum analysis (SSA) method, using a combination of geometric and statistical methods, is proposed as an analysis tool in order to detect anomalies on QoE indicator evolution.

Keywords Anomaly detection · QoE indicators · Singular spectrum analysis

 

Open Topics

General random coding bounds: AWGN channels to MIMO fading channels

Heung-No Lee¹ Jingqiao Zhang², Cheon Won Choi³

¹ Gwangju Institute of Science and Technology, GIST, Gwangju, South Korea
² Amazon.com, Seattle, USA
³ Dankook University, Yongin, South Korea

Abstract Random coding bounds are obtained for multiple-input multiple-output (MIMO) fading channels. To derive the result in a compact and easy-to-evaluate form, a series of combinatorial codeword enumeration problems are solved for input-constrained MIMO fading channels. The bounds obtained in this paper are shown useful as performance prediction measures for MIMO systems which employ turbo-like block codes as the outer code to derive the space-time inner code. The error exponents for MIMO channels are also derived from the bounds, and then compared with the classical Gallager error exponents as well as the channel capacities. The random coding bounds associated with the maximum likelihood receiver exhibit good match with the extensive system simulation results obtained with a turbo-iterative receiver.

Keywords Union bound . Random coding exponent . MIMO capacity

MUQAMI+: a scalable and locally distributed key management scheme for clustered sensor networks

Muhammad Khaliq-ur-Rahman Raazi Syed¹ · Heejo Lee² · Sungyoung Lee¹ Young-Koo Lee¹

¹ Department of Computer Engineering, Kyung Hee University, Seoul, Korea
² Divison of Computer & Communication Engineering, Korea University, Seoul, South Korea

Abstract Wireless sensor networks (WSN) are susceptible to node capture and many network levels attacks. In order to provide protection against such threats, WSNs require lightweight and scalable key management schemes because the nodes are resourceconstrained and high in number. Also, the effect of node compromise should be minimized and node capture should not hamper the normal working of a network. In this paper, we present an exclusion basis system-based key management scheme called MUQAMI+ for large-scale clustered sensor networks. We have distributed the responsibility of key management to multiple nodes within clusters, avoiding single points of failure and getting rid of costly inter-cluster communication. Our scheme is scalable and highly efficient in terms of re-keying and compromised node revocation.

Keywords Locally distributed · Key management · Sensor networks · Key revocation · Scalable key management · Flexible scheme

Analysis of energy-tax for multipath routing in wireless sensor networks

Md. Abdur Razzaque · Choong Seon Hong

Department of Computer Engineering, Kyung Hee University

Abstract Recently, multipath routing in wireless sensor networks (WSN) has got immense research interest due to its capability of providing increased robustness, reliability, throughput, and security. However, a theoretical analysis on the energy consumption behavior of multipath routing has not yet been studied. In this paper, we present a general framework for analyzing the energy consumption overhead (i.e., energy tax) resulting from multipath routing protocol inWSN. The framework includes a baseline routing model, a network model, and two energy consumption schemes for sensor nodes, namely, periodic listening and selective wake-up schemes. It exploits the influence of node density, link failure rates, number of multiple paths, and transmission environment on the energy consumption. Scaling laws of energy-tax due to routing and data traffic are derived through analysis, which provide energy profiles of single-path and multipath routing and serve as a guideline for designing energy-efficient protocols forWSN. The crossover points of relative energy taxes, paid by single-path and multipath routing, reception, and transmission, are obtained. Finally, the scaling laws are validated and performance comparisons are depicted for a reference network via numerical results.

Keywords Sensor network · Energy-tax analysis · Single-path routing · Multipath routing · Scaling law