Pubs:2008

<bibtex> @inproceedings{109, author={Sabine Moebs; Jennifer McManis}, title={A Learner, is a Learner, is a User, is a Customer - So what exactly do you mean by Quality of Experience?}, booktitle={Adaptive Hypermedia and Adaptive Web-based Systems}, year={2008},

abstract={An e-learner’s Quality of Experience (QoE) is informed by previous experiences as a learner, a user of computer/web-based systems, and a customer. This paper surveys different concepts for Quality of Experience (QoE) from different areas such as psychology, internet marketing, web engineering, systems and product development as well as philosophy of education. They are summarized into a proposal for a definition of Learner QoE in adaptive multimedia e-learning systems. A number of factors are identified that are likely to impact on QoE. We propose a <st1:place w:st="on">Delphi</st1:place> study to be used to provide an initial ranking of the importance of these factors. Additional user testing will be required to confirm the findings of this study.

 

},

keywords={adaptive hypermedia, quality of experience, educational philosophy}, pdf={ah_ws6_moebs_mcmanis.pdf}, } </bibtex> <bibtex> @inproceedings{162, author={C. Thorpe; S. Murphy; L. Murphy}, title={Analysis of Variation in IEEE802.11k Channel Load Measurements for Neighbouring WLAN Systems}, booktitle={ICT Mobile Summit}, year={2008}, abstract={This paper focuses on analysing the variation in IEEE802.11k channel load measurements for neighbouring WLAN systems. The channel load functionality was implemented in the QualNet simulation tool, and several scenarios were configured for testing. The effects of different numbers of active systems with different traffic patterns were examined. The results obtained indicate significant variation in channel load values calculated by different stations experiencing different levels of interference. This variation leads us to question the usefulness of a single channel load measurement; hence considerable care must be taken when using and interpreting such measurements. }, keywords={IEEE802.11k, Channel Load Measurements, Interference}, pdf={ICTMobileSummit_Paper_Camera_Ready.pdf}, } </bibtex> <bibtex> @inproceedings{183, author={Sabine Moebs}, title={A Learner, is a Learner, is a User, is a Customer - QoS-based Experience-aware Adaptation}, booktitle={ACM Multimedia}, year={2008}, abstract={This paper describes an outline of the doctoral thesis work concerning adaptation policies towards quality of experience (QoE) in performance-aware adaptive multimedia e-learning systems. QoE is considered to be mainly affected by the psychological concept of flow and learning-related factors. In turn, for multimedia systems, these factors can be heavily influenced by quality of service (QoS). In an ideal world, QoS would not be an issue and content optimally tailored to a user’s needs could always be perfectly delivered. Unfortunately, delivery conditions are not always ideal, and it may be infeasible to deliver certain multimedia content such as high quality video while maintaining an acceptable QoS. The goal of this research is to balance the constraints imposed by QoS restrictions with the requirements of flow and learning in order to produce the highest possible QoE for the learner using an adaptive multimedia system.}, keywords={Algorithms, Performance, Design, Human Factors, QoE, QoS, Flow, Learning}, pdf={smoebs_multimedia2008_ds.pdf}, } </bibtex> <bibtex> @inproceedings{184, author={S. Moebs; J. McManis}, title={ADAPTIVE SOCIAL CONNECTEDNESS IN A MULTIMEDIA E-LEARNING ENVIRONMENT}, booktitle={China-Ireland Conference on ICT (CIICT)}, year={2008}, abstract={Adaptive hypermedia systems are beneficial to e-learners in tailoring content to individual characteristics such as prior knowledge, learning preferences, etc. However, unlike popular non-adaptive learning management systems such as Moodle and Blackboard they do not support social connectedness by allowing communication with other learners. This can lead to feelings of isolation amongst learners and ultimately learner demotivation. Enabling communication has been shown to improve cohesion within a learner group and allows a tutor to monitor learner participation and intervene before learners become disengaged. This paper outlines a stand-alone component connect! for the selection of multimedia communication tools in adaptive e-learning systems to support social connectedness. In addition to the already proven benefits of supporting social interaction, attaching such a module to an adaptive hypermedia system allows us to introduce the novel feature of tailoring the communication method to the individual needs of the learner. We draw on research in the area of media ecology to assist us in making our decisions.}, keywords={adaptive systems, social connectedness}, pdf={moebs_mcmanis_adaptive_social_connectedness_final.pdf}, } </bibtex> <bibtex> @inproceedings{186, author={Seung-Bum Lee;Gabriel-Miro Muntean;Alan F. Smeaton}, title={Smart PIN: Utility-based Replication and Delivery of Multimedia Content to Mobile Users in Wireless Networks.}, booktitle={IEEE International Symposium on Broadband Multimedia Systems and Broadcasting 2008: Mobile and Handheld Systems for Entertainment on the Go}, year={2008}, abstract={Next generation wireless networks rely on heterogeneous connectivity technologies to support various rich media services such as personal information storage, file sharing and multimedia streaming. Due to users mobility and dynamic characteristics of wireless networks, data availability in collaborating devices is a critical issue. In this context Smart PIN was proposed as a personal information network which focuses on performance of delivery and cost efficiency. Smart PIN uses a novel data replication scheme based on individual and overall system utility to best balance the requirements for static data and multimedia content delivery with variable device availability due to user mobility. Simulations show improved results in comparison with other general purpose data replication schemes in terms of data availability.}, keywords={Content management, Non-real-time service, Interactive systems, Mobile systems, Portable and handheld devices}, } </bibtex> <bibtex> @inproceedings{187, author={Seung-Bum Lee;Gabriel-Miro Muntean;Alan F. Smeaton}, title={User-centric Utility-based Data Replication in Heterogeneous Networks.}, booktitle={IEEE International Conference on Communications, Workshop on Digital Television and Mobile Multimedia Broadcasting (ICC 2008)}, year={2008}, abstract={Information overload and convergence of devices aggravate the difficulties of accessing data distributed among various user devices especially when this is performed by mobile users and over heterogeneous wireless networks. Existing data replication systems help increase the performance of the distributed data system, but they do not consider users different levels of interest in various pieces of data and neither heterogeneous wireless connectivity issues. This paper presents the Smart Personal Information Network (Smart PIN), a performance and cost-aware personal information network which uses a novel usercentric utility-based data replication scheme to exchange content automatically, based on both network performance and user interests. The proposed user-centric data replication scheme s evaluation, through simulation, shows improved results in comparison with existing solutions.}, keywords={ Data replication, Utility Function, Heterogeneous Network}, } </bibtex> <bibtex> @inproceedings{193, author={Bogdan Ciubotaru; Gabriel-Miro Muntean}, title={M3S - Multimedia Mobility Management and Load Balancing in Wireless Broadcast Networks}, booktitle={China-Ireland International Conference on Information and Communications Technologies 2008 (CIICT 2008)}, year={2008}, pages={515-521}, abstract={Wireless local-area networks represent a viable broadband Internet access solution for enterprise, residential and public areas. Due to its short range radio, multiple wireless access points are necessary to cover a certain physical area. The tendency of mobile users to group in certain areas of interest and of mobile devices to connect to the access point with the highest signal strength determines the overall network load to be highly unbalanced. To overcome this issues which drastically affects user bandwidth share as well as the efficiency of network resource utilization, special load balancing techniques has to be employed. This paper presents the Multimedia Mobility Management System (M3S), a quality oriented mobility management framework which aims at maximizing user perceived multimedia quality by efficiently distributing the traffic load over all the communication resources available. Simulation based testing results are presented, outlining the performance of M3S against other load balancing techniques which rely on mobile device re-association with least congested access points.}, keywords={wireless broadcast networks, load balance, mobility management}, pdf={Ciubotaru_Muntean_CIICT08.pdf}, } </bibtex> <bibtex> @inproceedings{236, author={Kevin Collins, Gabriel-Miro Muntean}, title={Route-based Vehicular Traffic Management for Wireless Access in Vehicular Environments}, booktitle={Proceedings of 68th IEEE Vehicular Technology Conference Fall 2008}, year={2008}, abstract={Traffic congestion is a very serious problem which is becoming ever worse as the growth in the number of cars on the road significantly out-paces the provision of road capacity. This paper presents a novel vehicle routing algorithm for TraffCon - an innovative Traffic Management System for wireless vehicular networks - and discusses its complexity. The algorithm combats the traffic congestion problem by seeking to optimize the usage of the existing road capacity, reduce vehicle trip times and decrease fuel consumption and the consequent gas emissions. Results demonstrate that the algorithm significantly increases road capacity utilisation and consequently reduces traffic congestion in comparison with an existing approach.}, keywords={Wireless networking, Vehicular Communication, Road Traffic Congestion}, } </bibtex> <bibtex> @inproceedings{218, author={J. Fitzpatrick, S. Murphy, M. Atiquzzaman, J. Murphy}, title={ECHO: A Quality of Service based Endpoint Centric Handover scheme for VoIP}, booktitle={Wireless Communications and Networking Conference (WCNC)}, year={2008}, abstract={Existing terminal oriented handover mechanisms capable of meeting the strict delay bounds of real time applications such as VoIP do not consider the QoS of candidate handover networks. In this paper ECHO – a QoS based handover solution for VoIP– is proposed. ECHO is endpoint centric and does not require any network support; it leverages the SCTP transport protocol. ECHO incorporates network metrics that directly affect VoIP quality into the handover decision process. A dynamic variant of the ITU-T E-Model is used to calculate how the network metrics map to a user perceived voice quality metric known as the MOS. The MOS value is then used to make handover decisions between each of the available access networks. The results show that the addition of the QoS capabilities significantly improves the handover decisions that are made.}, keywords={ECHO, QoS, E-Model, SCTP, Handover, VoIP}, } </bibtex> <bibtex> @article{220, author={A. Nafaa; S. Murphy; L. Murphy}, title={Analysis of a Large-Scale VOD Architecture for Broadband Operators: A P2P-Based Solution}, journal={IEEE Communications Magazine}, year={2008}, pages={47-55}, volume={46}, abstract={VOD services distribution is gaining unprecedented interest from the consumer communication industry due to its growing success in both the Internet and residential broadband market. In this article we present a scalable VOD distribution architecture for broadband operators. The solution is based on a P2P streaming concept in which a VOD streaming session requested by a given STB (Set-Top-Box) is actually provisioned via a multisource streaming session. This solution has the advantage of scaling naturally with the number of STBs in the network. In this article we focus on efficiently translating the popularity distribution into content availability in the network. Different aspects related to this issue are analyzed and challenges highlighted. }, keywords={video on demand, peer-to-peer, popularity distribution, content availability}, } </bibtex> <bibtex> @article{221, author={Y. Qiao; E. Fallon; J. Murphy; L. Murphy; X. Zhu; G. Hayes; A. Matthews; A. Hanley}, title={Performance Analysis of Multi-homed Transport Protocols with Network Failure Tolerance}, journal={IET Communications}, year={2008}, pages={336-345}, volume={2}, abstract={This paper studies the performance of multi-homed transport protocols tolerant of network failure. It evaluates the performance of different retransmission policies combined with path failure detection thresholds, infinite or finite receive buffers for various path bandwidths, delays and loss rate conditions through SCTP simulation. The results show that retransmission policies perform differently with different path failure detection threshold configurations. It identifies that retransmission of all data on an alternate path with the path failure detection threshold set to zero performs best in symmetric path conditions but its performance degrades acutely in asymmetric path conditions even when the alternate path delay is shorter than the primary path delay. It illustrates that retransmission of all data on the same path with the path failure detection threshold set to one or zero gives the most stable performance in all path configurations. }, keywords={Fault-tolerant computing, transport protocols}, pdf={performance analysis.pdf}, } </bibtex> <bibtex> @article{222, author={A. Nafaa; T. Taleb; L. Murphy}, title={Forward Error Correction Strategies for Media Streaming over Wireless Networks}, journal={IEEE Communications Magazine}, year={2008}, pages={72-79}, volume={46}, abstract={The success of next-generation mobile communication systems depends on the ability of service providers to engineer new added-value multimedia-rich services, which impose stringent constraints on the underlying delivery/transport architecture. The reliability of real-time services is essential for the viability of any such service offering. The sporadic packet loss typical of wireless channels can be addressed using appropriate techniques such as the widely-used packet-level Forward Error Correction. In designing channel-aware media streaming applications, two interrelated and challenging issues should be tackled: accuracy of characterizing channel fluctuations and effectiveness of application-level adaptation. The first challenge requires thorough insight into channel fluctuations and their manifestations at the application level, while the second concerns the way those fluctuations are interpreted and dealt with by adaptive mechanisms such as FEC. In this article we review the major issues that arise when designing a reliable media streaming system for wireless networks. }, keywords={Forward error correction, multimedia streaming, wireless channel conditions}, } </bibtex> <bibtex> @inproceedings{223, author={Yang Yu;Sean Murphy;Liam Murphy}, title={A Clustering Approach to Planning Base Station and Relay Station Locations in IEEE 802.16j Multi-hop Relay Networks}, booktitle={Proc. IEEE International Conference on Communications (ICC 2008)}, year={2008}, abstract={In this paper, a clustering approach to solve a network planning problem for 802.16j relay networks is considered. Our clustering approach consists of three basic steps: (1) divide the nodes into k distinct clusters, (2) solve the planning problem separately for each cluster, and (3) perform a final optimization to reduce issues arising at cluster boundaries. Simulation results show that our approach is more efficient than existing approaches: solutions of equivalent quality can be found in 40% of the time. Thus our technique can be used to solve larger problems with similar hardware, or similar size problems in less time.}, keywords={network planning,802.16j,Wimax,relay network,clustering}, } </bibtex> <bibtex> @inproceedings{224, author={Yang Yu;Sean Murphy;Liam Murphy}, title={Planning Base Station and Relay Station Locations in IEEE 802.16j Multi-hop Relay Networks}, booktitle={Proc. 2nd IEEE Broadband Wireless Access Workshop, colocated with IEEE CCNC 2008}, year={2008}, abstract={In this paper, a problem formulation for determining optimal node location for Base Stations (BSs) and Relay Stations (RSs) in relay-based 802.16 networks is developed. The formulation results in an Integer Programming problem. A small modification to the original model is also considered in which the state space is reduced by limiting which nodes can be associated with which. Standard branch and bound techniques are used to solve the problem. The key findings of the paper are that standard techniques can be used to find solutions to problems of small metropolitan scale or for areas within a larger city.}, keywords={network planning,802.16j,Wimax,relay network}, } </bibtex> <bibtex> @article{228, author={Vasken Genc; Sean Murphy; Yang Yu; John Murphy}, title={IEEE 802.16j Relay-based Wireless Access Networks: An Overview}, journal={Wireless Communications}, year={2008}, pages={56-63}, volume={15}, abstract={Multihop wireless systems have the potential to offer improved coverage and capacity over single-hop radio access systems. Standards development organizations are considering how to incorporate such techniques into new standards. One such initiative is the IEEE 802.16j standardization activity, adding relay capabilities to IEEE 802.16 systems. This article provides an overview of this relay-based technology, focusing on some of the most pertinent aspects. In particular, the different modes of operation (transparent and non-transparent), framing structures, and network entry procedures are described. Some consideration of the issues in designing such systems is then given, which highlights when different features within the standard are most appropriate. As these systems are very new, many open issues remain to be resolved.}, keywords={802.16j, overview, design}, pdf={16jWCMag.pdf}, } </bibtex> <bibtex> @inproceedings{230, author={Vasken Genc; Sean Murphy; John Murphy}, title={An Interference-Aware Analytical Model for Performance Analysis of Transparent Mode 802.16j Systems}, booktitle={Broadband Wireless Access Workshop co-located with GLOBECOM}, year={2008}, abstract={In this paper, an interference-aware analytical model of IEEE 802.16j systems operating in transparent mode is described. The model can be used to determine the throughput gain that can be achieved by 802.16j relay- based systems under a max-min fairness constraint in which the difference between the data rate delivered to all subscribers is minimized. Two variants of the model are considered – one in which there is no spatial reuse and one in which there is spatial reuse. The study finds that this variant of 802.16j system can deliver significant gains over traditional single-hop access systems: 40% in the case in which there is no spatial reuse and up to 80% when spatial reuse is realised.}, keywords={IEEE 802.16j, optimisation problem, performance gain, transparent multihop relay}, pdf={camerayready-BWA08.pdf}, } </bibtex> <bibtex> @inproceedings{231, author={Vasken Genc; Sean Murphy; John Murphy}, title={Performance Analysis of Transparent Relays in 802.16j MMR Networks}, booktitle={WiOpt}, year={2008}, abstract={A simulation study of the performance of transparent mode relay-based 802.16j systems is described. The study focuses on the gain in throughput that is possible in omnidirectional relay systems and increases in signalling requirements that arise due to the multihop network architecture. The study finds that the introduction of transparent mode relays cannot deliver improved throughput for a substantial part of the coverage area of a Base Station (BS) – only approximately half of the total area covered by the BS can benefit from throughput enhancement. Further, the study shows that 802.16j based systems require significant signalling overhead, with almost twice that of 802.16e in the cases studied. Finally, the study demonstrates that in a topology with users uniformly distributed within the BS cell coverage, the maximum throughput increase on the downlink that can be achieved is relatively low. Much further work is necessary to realise useful gains from these systems.}, keywords={MMR, transparent multihop relay, performance, omnidirectional antenna}, pdf={wiopt08-cameraready.pdf}, } </bibtex> <bibtex> @inproceedings{235, author={Kevin Collins, Gabriel-Miro Muntean}, title={A Vehicle Route Management Solution for Wireless Vehicular Networks}, booktitle={27th IEEE Conference on Computer Communications (IEEE INFOCOM 2008): Mobile Networking for Vehicular Environments (MOVE 2008)}, year={2008}, abstract={Traffic Congestion is a very serious problem which is growing worse as the number of cars on the road continues to increase, out-pacing the provision of road capacity. This paper presents a novel vehicle routing algorithm for TraffCon - an innovative Traffic Management System for Wireless Vehicular Networks. The algorithm tackles the traffic congestion problem by seeking to optimize the usage of the existing road capacity, reduce vehicle trip times and decrease fuel consumption and the consequent gas emissions. Results demonstrate that the algorithm significantly reduces congestion, journey times and fuel consumption and emissions in comparison with an existing approach.}, keywords={Wireless networking, Vehicular Communication, Road Traffic Congestion}, } </bibtex> <bibtex> @inproceedings{237, author={Kevin Collins, Gabriel-Miro Muntean}, title={An Adaptive Vehicle Route Management Solution Enabled by Wireless Vehicular Networks}, booktitle={Proceedings of 68th IEEE Vehicular Technology Conference Fall 2008}, year={2008}, abstract={In order to accommodate the constantly growing number of vehicles on the road with which infrastructure provision is failing to cope, new means of optimizing the available road space are required. This paper presents a novel adaptive vehicle routing algorithm for TraffCon - an innovative Traffic Management System enabled by wireless vehicular networks. The algorithm combats the vehicular traffic congestion problem by seeking to optimize the usage of existing road capacity, while also minimising vehicle fuel consumption and emissions. Results demonstrate that the algorithm significantly increases road utilisation, reduces congestion, average journey times and fuel consumption in comparison with existing approaches.}, keywords={Wireless networking, Vehicular Communication, Road Traffic Congestion}, } </bibtex> <bibtex> @inproceedings{247, author={Hrishikesh Venkataraman; Gabriel-Miro Muntean}, title={Analysis of Random Data Hopping in Distributed Multihop Wireless Networks}, booktitle={TENCON, India}, year={2008}, abstract={Spatial reuse TDMA (time division multiple access) in multihop ad hoc network is a subject of intense research interest for next generation wireless systems. In this paper, the selection of concurrent communication pairs, that utilize the same resources, is formulated as a non-linear mixed integer programming problem. However, it has been found that the solution to this non-linear programming problem is NP-hard. Recently, a random data hopping (RDH) technique applied over a time slot partitioned system has been proposed by the authors as a novel heuristic algorithm. This random data hopping scheme is further studied in this paper for different values of traffic loads, and its performance is evaluated under realistic propagation conditions. It has been found that the variation of the system throughput with the traffic load follows a concave function, and it reaches its peak when the traffic load is around 30%.}, keywords={Spatial reuse TDMA, interference avoidance model, random data hopping.}, } </bibtex> <bibtex> @inproceedings{331, author={Parsons,T.;Mos,A.;Murphy,J.;Trofin,M.;Gschwind,T.}, title={Extracting Interactions in Component Based Systems}, booktitle={IEEE Transactions on Software Engineering}, year={2008}, abstract={Monitoring, analysing and understanding component based enterprise software systems are challenging tasks. These tasks are essential in solving and preventing performance and quality problems. Obtaining component level interactions which show the relationships between different software entities is a necessary prerequisite for such efforts. This paper focuses on component based Java applications, currently widely used by industry. They pose specific challenges while raising interesting opportunities for component level interaction extraction tools. We present a range of representative approaches for dynamically obtaining and using component interactions. For each approach we detail the needs it addresses, and the technical requirements for building an implementation of the approach. We also take a critical look at the different available implementations of the various techniques presented. We give performance and functional considerations and contrast them against each other by outlining their relative advantages and disadvantages. Based on this data, developers and system integrators can better understand the current state of the art and the implications of choosing or implementing different dynamic interaction extraction techniques.}, keywords={Distributed objects, components, containers, tracing.}, pdf={extracting.pdf}, } </bibtex> <bibtex> @inproceedings{332, author={Alocci,I.;Murphy,S.;Nafaa,A.;Murphy,J.}, title={Development of an IEEE 802.11s Simulation Model for QualNet}, booktitle={Networking & Electronic Commerce Research Conference}, year={2008}, abstract={In this work, an initial variant of an 802.11s simulation model for the QualNet simulator is described. The tool builds on the existing QualNet 802.11 model by adding capabilities suitable for mesh networking. More specifically, the model provides support for propagation of beacon frames in mesh networks and link establishment procedures by which nodes attach to the network.}, keywords={Networking,QOS}, pdf={development.pdf}, } </bibtex> <bibtex> @inproceedings{333, author={Qiao,Y.;Fallon,E.;Murphy,L.;Murphy,J.;Hanley,A.}, title={Path Selection of SCTP Fast Retransmission in Multi-Homed Wireless Environments}, booktitle={13th IFIP International Conference on Personal Wireless Communications}, year={2008}, abstract={In heterogeneous wireless network environments, network connections of a device may have a significant differential. This paper studies the effect of path bandwidth differential on the performance of fast retransmission strategies in Multi-homing environments. It identifies that fast retransmission on an alternate path may cause receive buffer blocking when path bandwidth differential is significant and the receive buffer is limited. A theoretical model is proposed for selecting retransmission path during the fast retransmission phase, which is based on receive buffer and path conditions. The model is verified through simulations with various path differentials.}, keywords={Wireless Communication}, pdf={path selection.pdf}, } </bibtex> <bibtex> @article{334, author={Trofin,M.;Murphy,J.}, title={Static Verification of Component Composition in Contextual Composition Frameworks}, journal={International Journal on Software Tools for Technology Transfers}, year={2008}, pages={247-261(15 pages)}, volume={10(3)}, abstract={Contextual component frameworks, such as Enterprise JavaBeans (EJB), allow for components to specify boundary conditions for the runtime context. These conditions are satisfied at runtime by services of the underlying platform, thus ensuring that the context in which components run exhibits properties that allow them to operate correctly. Depending on how components call each other, it is possible that satisfying such conditions lead to problems such as reduced performance due to redundant service execution, or permanent errors (composition mismatches), due to incompatible boundary conditions. Currently, the semantics of these boundary conditions are expressed in natural language only, making it impossible to incorporate them into an automatic analysis tool. Furthermore, early understanding of how components call each other would be necessary, but it is currently difficult to achieve by means of a tool, as the method dispatch rules in a component system differ from the dispatch rules of the programming language(s) in which they were developed. We have developed a metamodel, $${\mathbb{M}}$$ , for describing boundary conditions, an analysis method, $${\mathbb{A}}$$ , and a static component-level call graph extraction method for EJB applications, CHA EJB . $${\mathbb{A}}$$ uses $${\mathbb{M}}$$ models to analyze inter-component call graphs, and thus detect problems such as composition mismatches or redundancies, thus allowing for remedial action to take place. We present $${\mathbb{M}},{\mathbb{A}}$$ and CHA EJB in this article, show that $${\mathbb{A}}$$ produces correct results, and describe a prototype analysis tool implementing the three, which we used to validate our approach on two popular EJB applications. }, keywords={Software components - Contextual composition - Static analysis - Enterprise Java }, pdf={static verification.pdf}, } </bibtex> <bibtex> @inproceedings{335, author={Fallon,E.;Murphy,L.;Murphy,J.}, title={An Analysis of the Performance of an MIH Based Switch Strategy for Heterogenous Network Mobility}, booktitle={IEEE 17th IST Mobile & Wireless Communications Summit}, year={2008}, abstract={The increasingly ubiquitous deployment of wireless networks has created significant opportunities for mobile application developers. The availability of highcapacity, low financial cost networks has the potential to enable mobile application developers to offer feature-rich end-user-oriented product offerings. Standardisation efforts such as Media Independent Handover (MIH) will support this trend by providing developers with a detailed view of the financial cost and performance capabilities of available wireless and mobile networks. Even with the increasingly pervasive deployment of Wireless LAN (WLAN), it is unlikely those mobile applications will exclusively utilise WLAN networks, as many are deployed without consideration of seamless network mobility. In the scenario where WLAN coverage gaps exist, it will be necessary to utilise mobile networks such as UMTS as a communication bridge. In such an environment, the mobility support provided by multi-homed protocols such as the Stream Control Transmission Protocol (SCTP) has significant potential. This paper investigates how MIH performance characteristics - in particular the Received Signal Strength (RSS) from a WLAN Access Point (AP) - can be used to optimise SCTP switch performance. Results indicate that in certain situations there is a performance problem with utilising a "retransmit on same path" approach to lost packet retransmission when the primary path is explicitly set, as would be the case with MIH. Careful configuration of the RSS threshold for switchover is shown to alleviate the problem.}, keywords={SCTP, WLAN, Network Migration}, pdf={an analysis.pdf}, } </bibtex> <bibtex> @article{336, author={Parsons,T.;Murphy,J.}, title={Detecting Performance Antipatterns in Component Based Enterprise Systems}, journal={Journal of Optical Technology}, year={2008}, pages={55-90(36 pages)}, volume={7(3)}, abstract={We introduce an approach for automatic detection of performance antipatterns. The approach is based on a number of advanced monitoring and analysis techniques. The advanced analysis is used to identify relationships and patterns in the monitored data. This information is subsequently used to reconstruct a design model of the underlying system, which is loaded into a rule engine in order to identify predefined antipatterns. We give results of applying this approach to identify a number of antipatterns in two JEE applications. Finally, this work also categorises JEE antipatterns into categories based on the data needed to detect them.}, keywords={Component Systems,Antipatterns}, pdf={detecting performance.pdf}, } </bibtex> <bibtex> @inproceedings{404, author={S.Fallon;P.Jacob;Y.Qiao;L.Murphy;E.Fallon;A.Hanley}, title={An Analysis of Alterations to the SCTP RTO Calculation Mechanism for WLAN Environments}, booktitle={10th IFIP International Conference on Mobile & Wireless Communications Networks}, year={2008}, abstract={As a connection oriented transport layer protocol the Stream Control Transmission Protocol (SCTP) inherits many of the features of the Transmission Control Protocol (TCP) including the mechanism by which Retransmission Timeout (RTO) is calculated. Previous investigations have established that the mechanism through which SCTP calculates RTO is inappropriate in Wireless LAN (WLAN) environments. This paper investigates the performance implications of changes to the SCTP RTO calculation mechanism. In particular alterations to the parameters ?, the smoothing factor, and ?, the delay variance factor are investigated. Results indicate that performance improvements are achievable through careful selection of ? and ? values. Throughput improvements of 63% over the default mechanism defined in RFC 4960 are described. These performance improvements however, while significant, still can not address the switchover delays which result from the distortions caused by continuously increasing RTT values in WLAN environments.}, keywords={SCTP,TCP,Wireless LAN}, pdf={analysis.pdf}, } </bibtex> <bibtex> @article{405, author={O.Ashagi;S.Murphy;L.Murphy}, title={Interference Mitigation in License-exempt 802.16 systems:a distributed approach}, journal={Unlicensed Mobile Access Technology}, year={2008}, pages={49-50}, volume={August }, abstract={Operating in license-exempt IEEE 802.16 wireless spectrum is a challenging research issue. The research focus is on deriving intelligent algorithms to mitigate the interference that occurs between different users. In this chapter, we propose an enhancement to our previously published distributed approach to mitigate interference between 802.16 systems operating in close proximity, by introducing a re-listening mechanism to determine whether there are more subcarriers available in the channel than what the base stations (BSs) are currently using. Simulation results show that the re-listening mechanism offers a 100 percent throughput increase for some BSs. Our results also show the general trend of throughput variations between the downlink and the uplink, due to the differences in transmission power.}, keywords={IEEE 802.16,}, pdf={interference.pdf}, } </bibtex> <bibtex> @inproceedings{406, author={S.Fallon;P.Jacob;Y.Qiao;L.Murphy;E.Fallon;A.Hanley}, title={SCTP Switchover Performance Issues in WLAN Environments}, booktitle={IEEE Consumer Communications & Networking Conference(CCNC 2008)}, year={2008}, abstract={The increased number and diversity of underlying networks have made transparent network migration a necessity. Through its support for multi-homing the Stream Control Transmission Protocol (SCTP) enables seamless network mobility by abstracting multiple underlying physical paths into a single end-to-end association. One of these paths is selected as the primary. When a number of retransmission failures occur on the primary path, switchover is initiated to a secondary path. The number of retransmission attempts before switchover is initiated can be configured; however, the delay between each retransmission is managed internally in SCTP using a Retransmission TimeOut (RTO) value. This paper shows that the current SCTP mechanism for calculating RTO values is inappropriate in WLAN environments, since increased Round Trip Times (RTT) significantly distort RTO calculations. Experimental and simulated results indicate that SCTP behaves in a counterintuitive manner which allows more time for switchover as network conditions degrade: delays of up to 187 seconds can be experienced before switchover occurs. We show that additional SCTP parameters need to be carefully configured in order to reduce this switchover delay to a more acceptable level.}, keywords={SCTP, WLAN, Switchover, Heterogeneous Networks}, pdf={sctp.pdf}, } </bibtex> <bibtex> @article{425, author={C.H.Muntean}, title={Improving Learner Quality of Experience by Content Adaptation based on Network Conditions}, journal={Computers in Human Behaviour}, year={2008}, pages={1452-1472}, volume={24}, abstract={Apart from user characteristics, properties of the network over which the content is delivered and device on which the content is displayed affect end-user perceived quality. This paper presents a learner quality of experience (QoE) model that apart from the user-related content adaptation, considers delivery performance-based content personalisation in order to improve user experience when interacting with an online learning system. A comparison-based study on the benefit of using the proposed learner QoE model in adaptive and personalized education was conducted involving the original AHA! and QoEAHA – a version of AHA! enhanced with the learner QoE model. Testing results demonstrate significant benefits in terms of learning achievement, learning performance, learner navigation and user QoE in favour of the learner QoE model-enhanced solution.}, keywords={QoE}, pdf={Muntean_2008_Computers-in-Human-Behavior.pdf}, } </bibtex> <bibtex> @inproceedings{436, author={B.Ciubotaru;Gabriel-Miro Muntean}, title={M3S-Multimedia Mobility Management & Load Balancing in Wireless Broadcast Networks}, booktitle={IET Chine-Ireland International Conference on Information & Communications Technology}, year={2008}, abstract={Wireless local-area networks represent a viable broadband Internet access solution for enterprise, residential and public areas. Due to its short range radio, multiple wireless access points are necessary to cover a certain physical area. The tendency of mobile users to group in certain areas of interest and of mobile devices to connect to the access point with the highest signal strength determines the overall network load to be highly unbalanced. To overcome this issues which drastically affects user bandwidth share as well as the efficiency of network resource utilization, special load balancing techniques has to be employed. This paper presents the multimedia mobility management system (M3S), a quality oriented mobility management framework which aims at maximizing user perceived multimedia quality by efficiently distributing the traffic load over all the communication resources available. Simulation based testing results are presented, outlining the performance of M3S against other load balancing techniques which rely on mobile device re-association with least congested access points}, keywords={Multimedia,Wireless Networks,Mobile Communication}, } </bibtex> <bibtex> @inproceedings{446, author={C.Xu;Gabriel-Miro Muntean;E.Fallon;A.Hanley;F.Karayel}, title={A Balanced Tree-based Strategy for Unstructured Media Distribution in P2P Networks}, booktitle={IEEE International Conference on Communication}, year={2008}, abstract={Most research on P2P multimedia streaming assumes that users access video content sequentially and passively. Unlike P2P live streaming in which the peers start playback from the current point of streaming when they join the streaming session, in P2P video-on-demand streaming VCR-like operations such as forward, backward, and random-seek have to be supported. Providing this level of interactive streaming service in a P2P environment is a significant challenge. This paper proposes a Balanced Binary Tree-based strategy for Unstructured video-ondemand distribution in P2P networks (BBTU). BBTU assumes videos can be divided into several segments which can be fetched from different peers. BBTU involves two steps: 1) balance binary tree construction based on a prefetching algorithm in order to support interactivity; 2) unstructured video dissemination over network based on gossip protocol, which is the overlay for video distribution. Analysis and simulation show how BBTU is an efficient interactive streaming solution in P2P environment.}, keywords={P2P video-on-demand; interactivity; balanced}, pdf={a balanced.pdf}, } </bibtex> <bibtex> @inproceedings{447, author={C.XU;Gabriel-Miro Muntean;E.Fallon;X.Li}, title={DONET-VOD:A Hybrid Overlay Solution for Efficient Peer-to-Peer Video on Demand Services}, booktitle={IEEE International Conference on Multimedia & Expo(ICME)}, year={2008}, abstract={The existing DONet-based approach uses successfully a random gossip algorithm for scalable live video streaming. This pure mesh overlay network-based solution may lead to unacceptable latency or even failure of VCR operations in Video-on-Demand (VoD) services where nodes usually have different playing offsets, across a wide range. This paper proposes DONet-VoD which enhances DONet in order to address issues related to VoD delivery and VCR operations. In DONet-VoD, DONet principle is employed for the video distribution over the overlay network and a novel algorithm which uses a multi-way tree structure and extra prefetching buffers at the nodes is proposed to support efficient VoD operations. Video segments are prefetched and stored in a distributed manner in the nodes’ prefetching buffer along the tree. The cooperation between DONetbased video delivery and the tree-located multimedia components enable multimedia streaming interactive commands to be performed efficiently. This paper presents and discusses the prefetching scheme, details the cooperation procedure, and then analyses the performance of the proposed DONet-VoD}, keywords={Peer-to-peer, VoD, prefetching, multiway}, pdf={donet.pdf}, } </bibtex> <bibtex> @inproceedings{448, author={C.Xu;Y.Qiao;E.Fallon;Gabriel-Miro Muntean}, title={Comparitive Study of Real-Time Multimedia Transmission over Multi-Homing Transport Protocols}, booktitle={IEEE /IFIP International Conference on Management of Multimedia Networks & Services}, year={2008}, abstract={The availability of multimedia applications suitable for deployment using 3G and GPRS networks has led to a requirement for end-to-end quality of service. More efficient mechanisms are needed in order to provide the required end user quality of service in wireless data networks. This paper investigates the performance implications of transmitting real-time multimedia content over a multi-homed transport protocol in a manner which is tolerant of network failure. It evaluates video quality with different retransmission policies combined with various path failure detection thresholds, path bandwidths, delays and loss rate conditions through Partial Reliable Stream Control Transmission Protocol (PRSCTP). A solution called Evalvid-SCTP, which is a trace driven simulation of MPEG-4 video over SCTP, was designed to achieve the performance evaluation.}, keywords={PR-SCTP, Multi-homing, MPEG-4 Video, Congestion Control}, pdf={comparitive study.pdf}, } </bibtex> <bibtex> @article{453, author={C.H.Muntean;Gabriel-Miro Muntean}, title={Open Corpus Architecture for Personalised Ubiquitous e-Learning}, journal={Personal & Ubiquitous Computing}, year={2008}, pages={197-205}, volume={13}, abstract={As the e-learning area matures, there are a growing number of e-learning content providers that produce and distribute material that covers a large range of topics, differs in quality and is represented in various formats. Lately, different devices and various network technologies allow extensive user access to educational content almost anywhere, anytime and from any device. Ubiquitous e-learning has the potential to provide continuous and context-based, educational material to human learners anytime, anywhere and on any device. Since each person has different expectations related to the content, the performance of the delivery and display of that content, it is desirable for an ubiquitous e-learning environment to provide user-oriented personalisation of e-learning material. However very often there are multiple sources of e-learning material at various web locations (open corpus resources) that cover the same topic, but differ in terms of quality, formatting and even cost. It is very difficult for learners to select the content that best suits their interests and goals, characteristics of the device used and delivery network as well as their cost budget. This paper proposes an innovative ubiquitous e-learning environment called Performance-based E-learning Adaptive Cost-efficient Open Corpus frameworK (PEACOCK) that provides support for the selection and distribution of personalised e-learning rich media content (e.g. multimedia, pictures, graphics and text) to e-learners such as it will best suit users’ interests and goals, meet their formatting preferences and cost constraints, while considering the limitations introduced by the end-user devices and the delivery networks to the user. PEACOCK’s main goal is to maximise the users’ e-learning experience and increase their learning satisfaction and learning outcome.}, keywords={Adaptive e-learning systems �}, pdf={open corpus.pdf}, } </bibtex> <bibtex> @article{454, author={Gabriel-Miro Muntean;G.Ghinea;T.N.Sheehan}, title={Region of Interest-based Adaptive Multimedia Streaming Scheme}, journal={IEEE Trans. on Broadcasting}, year={2008}, pages={296-303}, volume={54}, abstract={Adaptive multimedia streaming aims at adjusting the transmitted content based on the available bandwidth such as losses that often severely affect the end-user perceived quality are minimized and consequently the transmission quality increases. Current solutions affect equally the whole viewing area of the multimedia frames, despite research showing that there are regions on which the viewers are more interested in than on others. This paper presents a novel region of interest-based adaptive scheme (ROIAS) for multimedia streaming that when performing transmission-related quality adjustments, selectively affects the quality of those regions of the image the viewers are the least interested in. As the quality of the regions the viewers are the most interested in will not change (or will involve little change), the proposed scheme provides higher overall end-user perceived quality than any of the existing adaptive solutions.}, keywords={Content adaptation, multimedia streaming,}, pdf={region.pdf}, } </bibtex> <bibtex> @article{455, author={Gabriel-Miro Muntean;G.Ghinea;P.Frossard;M.Etoh;F.Speranza;H.R.Wu}, title={Advanced Solutions for Quality-Oriented Multimedia Broadcasting}, journal={IEEE Trans. on Broadcasting}, year={2008}, pages={494-498}, volume={54}, abstract={Multimedia content is increasingly being delivered via different types of networks to viewers in a variety of locations and contexts using a variety of devices. The ubiquitous nature of multimedia services comes at a cost, however. The successful delivery of multimedia services will require overcoming numerous technological challenges many of which have a direct effect on the quality of the multimedia experience. For example, due to dynamically changing requirements and networking conditions, the delivery of multimedia content has traditionally adopted a best effort approach. However, this approach has often led to the end-user perceived quality of multimedia-based services being negatively affected. Yet the quality of multimedia content is a vital issue for the continued acceptance and proliferation of these services. Indeed, end-users are becoming increasingly quality-aware in their expectations of multimedia experience and demand an ever-widening spectrum of rich multimedia-based services.}, keywords={Multimedia,Network}, pdf={advanced solution.pdf}, } </bibtex> <bibtex> @inproceedings{477, author={Mathias Kretschmer; Sebastian Robitzsch; Christian Niephaus; Karl Jonas; Gheorghita Ghinea}, title={Wireless Mesh Network Coverage with QoS Differentiation for Rural Areas}, booktitle={First International Workshop on Wireless Broadband Access for Communities and Rural Developing Regions}, year={2008}, abstract={...}, keywords={WMN}, } </bibtex> <bibtex> @inproceedings{478, author={Andreas Roos; Sebastian Robitzsch; Bangnan Xu; Sabine Wieland; Andreas Schwarzbacher}, title={Service quality improvement based on Network Attachment Subsystem extensions and Service Enhancement Function - Mesh Networks as an example}, booktitle={13th International Telecommunications Network Strategy and Planning Symposium}, year={2008}, abstract={...}, keywords={WMN, Security}, } </bibtex>