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  • 401. Fiedler, Markus
    et al.
    Chevul, Stefan
    Isaksson, Lennart
    Tutschku, Kurt
    Binzenhöfer, Andreas
    The Throughput Utility Function: Assessing network impact on mobile services2005Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Ett nytt sätt att uttrycka nätverkets inflytande på tjänstekvaliten (skala från 0 till 100) för mobila tjänster.

  • 402. Fiedler, Markus
    et al.
    Chevul, Stefan
    Radtke, Olaf
    Tutschku, Kurt
    Binzenhöfer, Andreas
    The Network Utility Function: A practicable concept for assessing network impact on distributed services2005Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Ett nytt sätt att uttrycka nätverkets inflytande på tjänstekvaliten (skala från 0 till 100). Undersökt scenario: trace-driven OPNET simulering av videokonferenser och TCP strömmar via flaskhalsar (t ex ADSL länkar).

  • 403. Fiedler, Markus
    et al.
    Ekelin, Annelie
    Dittrich, Yvonne
    Eriksén, Sara
    E-government as co-construction: Networks, accountability, and working relations of technology production and use2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    The project within which this paper was co-authored focuses on the domain of e-government and is a deliberate attempt by the involved partners to cultivate and expand local and regional spaces for situated innovation, design and development of public services and ICT use in the public sector. Our starting point is e-government understood as co-construction. The project is currently being funded by the Innovative Actions within ERDF, the European Regional Development unding. The partners of the e-overnment arena are public service providers, ICT providers and researchers from a number of different disciplines. In this paper, we focus on communication networks and accountability. Are communication networks enablers or disablers for e-government services, and how can they be held accountable to their users? To what extent might we need to help each other unpack ‘black boxes’ and exchange them for ‘glass boxes’ in communicating with users and across disciplinary boundaries? Using metaphors and models from telecommunications, software engineering, informatics, business administration and human work science, and inspired by the Scandinavian tradition of Participatory Design, we attempt to establish a common basis to explore the evolving technologies and practices in e-government.

  • 404. Fiedler, Markus
    et al.
    Eliasson, Charlott
    Chevul, Stefan
    Eriksén, Sara
    Quality of Experience and Quality of Service in a Service Supply Chain2007Konferensbidrag (Övrigt vetenskapligt)
    Abstract [sv]

    Bidraget behandlar sammanhanget mellan användarupplevt tjänstekvalitet och störningar på nätverksnivå med speciell hänsyn till tjänster som formas som kedjor. Det relateras till ett pågående projekt där kvaliten av karttjänster ska kartläggas. Användarupplevt tjänstekvalitet, nätverksprestanda, GIS system, karttjänster

  • 405. Fiedler, Markus
    et al.
    Eliasson, Charlott
    Ciszkowski, Tomasz
    Mazurczyk, Wojciech
    Kotulski, Zbigniew
    Parameterisation of a reputation system for VoIP in P2P networks for improved communication quality and security2008Konferensbidrag (Övrigt vetenskapligt)
    Abstract [sv]

    Pappret utvecklar ett "ryktessystem" (reputation system) som kombinerar uppmätta kommunikationskvalitets- och säkerhetsparametrar som unterlag för vägvalet i ett Peer-to-Peer (P2P) nätverk.

  • 406. Fiedler, Markus
    et al.
    Hasslinger, Gerhard
    Waiting Time Quantiles for the Gaussian Voice Traffic Model2002Övrigt (Övrigt vetenskapligt)
    Abstract [sv]

    Pappret presenterar och dikuterar en enkel approximationsformel som kan användas bl a för att dimensionera en nätverkslänk på ett sådant sätt att en önskad väntetid överskris enbart med typ 1 % sannolikhet. Statistisk multiplexeringsvinst, Gauss trafik, On-Off källor, tjänstekvalitet, väntetidskvantil

  • 407. Fiedler, Markus
    et al.
    Hlavacs, Helmut
    Hackbarth, Klaus
    Arlos, Patrik
    Quality of experience. 1- Metrics and performance evaluation2010Ingår i: Annales des télécommunications, ISSN 0003-4347, E-ISSN 1958-9395, Vol. 65, nr 1-2, s. 1-2Artikel i tidskrift (Refereegranskat)
  • 408. Fiedler, Markus
    et al.
    Hlavacs, Helmut
    Hackbarth, Klaus
    Arlos, Patrik
    Quality of experience 2: Socio-economic aspects2010Ingår i: Annales des télécommunications, ISSN 0003-4347, E-ISSN 1958-9395, Vol. 65, nr 3-4, s. 1-2Artikel i tidskrift (Refereegranskat)
  • 409. Fiedler, Markus
    et al.
    Hock, David
    Hossfeld, Tobias
    Binzenhöfer, Andreas
    Tutschku, Kurt
    Tran-Gia, Phuoc
    A natural relation between user-perceived quality and network-level perturbations2006Konferensbidrag (Övrigt vetenskapligt)
    Abstract [sv]

    Pappret diskuterar ett naturligt samband mellan användarupplevt tjänstekvalitet och nätverksstörningar i form av en exponentialfunktion. Användarupplevt tjänstekvalitet, nätverksprestanda

  • 410. Fiedler, Markus
    et al.
    Hossfeld, Tobias
    Quality of Experience-related differential equations and provisioning-delivery hysteresis2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Churn of revenue-generating and dissatisfied users has become a major point of concern for service providers and network operators. As services rely on interconnecting networks, service performance and thus user satisfaction depend on network performance. Consequently, it is of utmost importance to understand the relationships between user perception, captured by quantitative Quality of Experience (QoE) parameters, and network performance, described by Quality of Service (QoS) parameters. This paper provides insights into fundamental relationships between QoE and QoS, formulated as partial differential equations describing changes in QoE with respect to specific QoS parameters. A set of illustrating examples from the literature is given. Furthermore, the different impacts of provisioning and degree of success or failure of delivery on QoE are discussed, leading to the QoE provisioning-delivery hysteresis. This hysteresis provides a striking motivation for employing elastic adaptation mechanisms to available resources instead of suffering from uncontrolled data loss.

  • 411. Fiedler, Markus
    et al.
    Hossfeld, Tobias
    Norros, Ilkka
    Rodrigues, Joel
    Pereira, Paulo Rogério
    The Network of Excellence Euro-NF and its Specific Joint Research Projects2011Ingår i: ICaST: ICST's Global Community Magazine (online)Artikel i tidskrift (Refereegranskat)
    Abstract [sv]

    Artikeln ger en överblick över Euro-NF och dess aktivititer. Speciellt behandlas SJRP konceptet, ilket betyder specifika gemensamma forskningsprojekt som inkubator för gemensamma publikationer och större uppföljande projekt. Tre utvalda projekt presenteras i detalj.

  • 412. Fiedler, Markus
    et al.
    Hossfeld, Tobias
    Tran-Gia, Phuoc
    A generic quantitative relationship between Quality of Experience and Quality of Service2010Ingår i: IEEE Network, ISSN 0890-8044, E-ISSN 1558-156X, Vol. 24, nr 2, s. 36-41Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quality of Experience (QoE) ties together user perception, experience and expectations to application and network performance, typically expressed by Quality of Service (QoS) parameters. Quantitative relationships between QoE and QoS are required in order to be able to build effective QoE control mechanisms onto measurable QoS parameters. On this background, this paper proposes a generic formula in which QoE and QoS parameters are connected through an exponential relationship, called IQX hypothesis. The formula relates changes of QoE with respect to QoS to the current level of QoE, is simple to match, and its limit behaviours are straighforward to interpret. It validates the IQX hypothesis for streaming services, where QoE in terms of Mean Opinion Scores (MOS) is expressed as functions of loss and reordering ratio, the latter of which is caused by jitter. For web surfing as the second application area, matchings provided by the IQX hypothesis are shown to outperform previously published logarithmic functions. We conclude that the IQX hypothesis is a strong candidate to be taken into account when deriving relationships between QoE and QoS parameters.

  • 413. Fiedler, Markus
    et al.
    Isaksson, Lennart
    Chevul, Stefan
    Karlsson, Johan
    Lindberg, Peter
    Measurements and analysis of application-perceived throughput via mobile links2005Konferensbidrag (Refereegranskat)
    Abstract [sv]

    En grundlig redovising av throughput-mätningar och deras innebörd i mobila miljöer; samtidig en demonstration att den ekvivalenta flaskhalsmodellen kan användas för fördröjningsuppskattningar

  • 414. Fiedler, Markus
    et al.
    Krieger, Udo R.
    The impact of varying channel capacity on the quality of advanced data services in PCS networks2000Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Ett modell som kan modellera den varierande kapaciteten av en trådlös länk beskrivs. Det visas hur hastigheten på ändringarna av kapaciteten påverkar tjänstekvalitén. Flödesmodell, Gilbert-Elliott modell, prestandaberäkningar

  • 415. Fiedler, Markus
    et al.
    Persson, Mårten
    Bertilsson, Tobias
    Situationsberoende spontan mobil informationstjänst för resenärer2005Övrigt (Övrigt vetenskapligt)
    Abstract [sv]

    This contribution describes a service (application) that provides travelers with up-to-date and relevant information while traveling. The service is planned to become part of the demonstration of seamless communications within the VINNOVA-sponsored project PIITSA = Personal Information for Intelligent Transport Systems through Seamless communications and Autonomous decisions. The application will combine streaming and interactive service in order to provide a traveler with spontaneous information regarding current disturbances affecting its travel and proposals of alternative routes, both using seamless communications. The service is designed and implemented by students from the BTH course ETD013 "Mobile Services".

  • 416. Fiedler, Markus
    et al.
    Tran-Gia, Phuoc
    Performance assessment for new internet services2010Ingår i: International Journal of Communication Networks and Distributed Systems, ISSN 1754-3916, E-ISSN 1754-3924, Vol. 4, nr 2, s. 131-132Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Internet has shown to be the major enabler for a large variety of services via a common infrastructure. Since early applications such as remote login, e-mail, file transfer and web browsing, many new applications and services have entered the stage, where overlay networks play an important role. When broadband access technologies reached private users, file sharing became popular. Telecommunication providers have discovered internet technology as a cost-saving alternative to classical telecom technology. 3GPP has standardised the IP multimedia system (IMS), which is nowadays also used in the world of fixed access networks to handle the coexistence of voice, TV and internet (so-called Triple Play) on access links. New application domains such as e-health, e-government, e-tourism, etc., have emerged. Many new services use other services, forming composite services or service supply chains based on internet. So, the ‘anything-over-IP-over-anything’ principle has become a reality. This emergence of new applications raises challenges. The internet has never been designed for fulfilling all imaginable application’s needs, nor to maximise user’s quality of experience (QoE). During the years, the basic best-effort paradigm has been enhanced by network-level quality of service (QoS) measures. Still, internet packet delivery cannot be guaranteed. Applications try to adapt themselves to these volatile conditions, e.g., by modifying the intensity of the data flows or adding some kind of redundancy to be used for error correction, which fits the internet principle of end-to-end control. However, in order to reach the right interplay between applications and services and the internet infrastructure, a good understanding of the characteristics of both is mandatory. On this background, this special issue focuses on performance assessment of contemporary, new and emerging applications and services using the internet.

  • 417. Fiedler, Markus
    et al.
    Tutschku, Kurt
    Application of the stochastic fluid flow model for bottleneck identification and classification2003Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Den (inom teletrafikteorin välkända) flödesmodellen används för att beskriva konsekvenserna av en flaskhals på dataströmmar som passerar den: hastighetsstatistiken förändras beroende på typen av flaskhalsen och tvärtrafik. Flödesmodellen visar sig vara mycket lämpligt att bekriva fenomenerna. Nyckelord: Internet, flaskhals, flödesmodell, prestanda, management, hastighetsstatistik

  • 418. Fiedler, Markus
    et al.
    Tutschku, Kurt
    Carlsson, Patrik
    Nilsson, Arne A.
    Identification of performance degradation in IP networks using throughput statistics2003Konferensbidrag (Refereegranskat)
    Abstract [sv]

    En flaskhalsindikator som bygger på att ta differensen på hastighets-/genomströmningshistogram efter och framför en flaskhals introduceras. Den tillämpas på en videokonferens som störs på kontrollerat sätt av annan trafik. Nyckelord: Internet, flaskhals, flödesmodell, hastighetsstatistik

  • 419. Fiedler, Markus
    et al.
    Voos, Holger
    New results on the numerical stability of the stochastic fluid flow model analysis2000Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Pappret identifierar anledningar varför den stokastiska flödesmodellen analysen gärna kantrar numeriskt sett och berättar om möjliga åtgärder. Flödesmodell, QoS, numerisk analys, Eigensystem, linjär ekvationssystem

  • 420.
    Fiedler, Markus
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Wac, Katarzyna
    Bults, Richard
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Estimating performance of mobile services from comparative output-input analysis of end-to-end throughput2013Ingår i: IEEE Transactions on Mobile Computing, ISSN 1536-1233, E-ISSN 1558-0660, Vol. 12, nr 9, s. 1761-1773Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mobile devices with ever-increasing functionality and the ubiquitous availability of wireless communication networks are driving forces behind innovative mobile applications enriching our daily life. One of the performance measures for a successful application deployment is the ability to support application-data flows by heterogeneous networks within certain delay boundaries. However, the quantitative impact of this measure is unknown and practically infeasible to determine at real-time due to the mobile device resource constraints. We research practical methods for measurement-based performance evaluation of heterogeneous data communication networks that support mobile application-data flows. We apply the lightweight Comparative Output-Input Analysis (COIA) method estimating an additional delay based on an observation interval of interest (e.g., one second) induced on the flow. An additional delay is the amount of delay that exceeds non-avoidable, minimal end-to-end delay caused by the networks propagation, serialization and transmission. We propose five COIA methods to estimate additional delay and we validate their accuracy with measurements obtained from the existing healthcare and multimedia streaming applications. Despite their simplicity, our methods prove to be accurate in relation to an observation interval of interest, and robust under a variety of network conditions. The methods offer novel insights into application-data delays with regards to the performance of heterogeneous data communication networks.

  • 421.
    Fiedler, Markus
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Lundberg, Lars
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Arlos, Patrik
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    QoE-based Cross-Layer Design of Mobile Video Systems: Challenges and Concepts2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    This conceptual paper focuses on revealing challenges and offering concepts associated with the incorporation of the Quality of Experience (QoE) paradigm into the design of mobile video systems. The corresponding design framework combines application, middleware and networking layer in a unique cross-layer approach, in which all layers shall jointly analyse the quality of the video and its delivery in face of volatile conditions. Particular ingredients of the framework are efficient video processing, advanced realtime scheduling, and reduced-reference metrics on application and network layer.

  • 422.
    Fotrousi, Farnaz
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Fricker, Samuel
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för programvaruteknik.
    Fiedler, Markus
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Quality Requirements Elicitation based on Inquiry of Quality-Impact Relationships2014Ingår i: Proceedings of International Requirements Engineering, IEEE , 2014, s. 303-312Konferensbidrag (Refereegranskat)
    Abstract [en]

    Quality requirements, an important class of non functional requirements, are inherently difficult to elicit. Particularly challenging is the definition of good-enough quality. The problem cannot be avoided though, because hitting the right quality level is critical. Too little quality leads to churn for the software product. Excessive quality generates unnecessary cost and drains the resources of the operating platform. To address this problem, we propose to elicit the specific relationships between software quality levels and their impacts for given quality attributes and stakeholders. An understanding of each such relationship can then be used to specify the right level of quality by deciding about acceptable impacts. The quality-impact relationships can be used to design and dimension a software system appropriately and, in a second step, to develop service level agreements that allow re-use of the obtained knowledge of good-enough quality. This paper describes an approach to elicit such quality-impact relationships and to use them for specifying quality requirements. The approach has been applied with user representatives in requirements workshops and used for determining Quality of Service (QoS) requirements based the involved users’ Quality of Experience (QoE). The paper describes the approach in detail and reports early experiences from applying the approach. Index Terms-Requirement elicitation, quality attributes, non-functional requirements, quality of experience (QoE), quality of service (QoS).

  • 423.
    Fristedt, Pia
    et al.
    Blekinge Tekniska Högskola, Institutionen för ekonomi och samhällsvetenskap.
    Hedvall, Maria
    Blekinge Tekniska Högskola, Institutionen för ekonomi och samhällsvetenskap.
    XML Web Services and the paradigm shift in the Telecom Industry2003Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    There are a lot of changes happening in the telecom industry now since the Telecom and Internet is converging. Another thing playing a big role is that the new technology, Web Services, is emerging. Since new technology and changes in businesses goes hand in hand, there is a need to map these changes and see how to make money of the new technology in the telecom industry.

  • 424.
    Gabriel, Karim
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Moudarres, Sani Al
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    The development of a Speech Level Adjustment Technique for late Deaf People2009Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    People that become deaf later on in life do have the ability to speak with correct pronunciation but since they can not hear their own voice nor the noise in the enviroment, they have difficulties to adjust their voice level to the surrounding environment. In this thesis we propose and algorithm which can be used on a prototype to help the late deafened people to adjust their voice level to the surrounding.

  • 425.
    Gade, Praveen Kumar
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Osuri, Manjit
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Evaluation of Multi Criteria Decision Making Methods for Potential Use in Application Security2014Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    The first chapter introduces the thesis work. The second chapter presents the background of decision making models, their process, and the classification of decision making models. The third chapter presents the research methodology we have used in different phases which aims to answer the research questions. The fourth chapter gives a detailed literature study of how decision models can be used in application security. The fifth chapter evaluates selected decision models. The sixth chapter concludes the thesis and presents future work.

  • 426.
    Gade, Vaibhav
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Intrusion Detection System as a Service: Providing intrusion detection system on a subscription basis for cloud deployment2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 427.
    Gafur, Abdul
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Dispersion Effects on OCDMA System Performance2009Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    This thesis presents the effect of dispersion and Multi Access Interference (MAI) of optical fiber on the Bit Error Rate (BER) performance of a Direct Sequence Optical Code Division Multiple Access (DS-OCDMA) network by means of intensity modulation and optical receiver correlators. By using Matlab simulations, Signal-to-Noise Ratio (SNR) versus Received Optical Power (ROP) of an OCDMA transmission system can be evaluated with a so-called 7-chip m-sequence for different numbers of system users. This can be done for the ROP versus BER for various lengths of single mode optical fiber by taking into consideration the dispersion effect in the optical fiber. Matlab simulations can be performed in order to illustrate the reduction of the dispersion index gamma, or to visualize different scenarios, e.g., what amount of transmitted power is required in order to obtain a BER of 10-9 when the length of the optical fiber is increased.

  • 428.
    Gagbla, George Kofi
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Applying Keystroke Dynamics for Personal Authentication2005Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    With the establishment of the information society, security had become the greatest concern for Institutions transacting business over the Internet. Home banking and on-line brokerage applications currently, use basic software-only security functions for the internet such as server authentications and Secure Sockets layer. Higher levels of protections are being achieved with Smart card based authentication schemes and transaction protocols. Password based security identifies users based on what they know – the password or PIN, which can be guessed, hacked, found or stolen. Smart Cards, tokens and badges identify users based on what they have which can also be lost, loaned or stolen. The objective of the thesis was to design and implement a biometric authentication scheme by means of keystroke dynamics to secure web applications. The scheme illustrates the effect of the template size and the number of biometric features used to improve performance of FAR, FRR and EER. The enrolment process is devoid of spurious outliers that may introduce significant variations to template data. Due to the dependence of the system on the user’s psychological characteristics, the adaptation module introduces dynamism into the template features per changes in the legitimate user’s login template variants. At the quest of attaining a zero bias in statistical variants, an off-line simulator tool was designed to regenerate impostor and genuine data set obtained from live users and set as input to the system. The report includes an architectural description of the system, conceptual models and analysis of field data of over 200 samples.

  • 429. Gajowniczek, Piotr
    et al.
    Pióro, Michal
    Arvidsson, Åke
    VP reconfiguration through Simulated Allocation1996Konferensbidrag (Refereegranskat)
    Abstract [en]

    VP reconfiguration is a powerful and flexible tool to cope with traffic changes and/or equipment failures in ATM networks. In the paper we present an application of a stochastic optimization algorithm called Simulated Allocation to the problem of VP reconfiguration in response to traffic shifts. The considered optimization task takes into account the cost of VPs reconfiguration imposed by changes in VP routing tables, rearrangement and possible loss of some calls in progress. Numerical results illustrating the effectiveness of the Simulated Allocation algorithm are given.

  • 430.
    Garapati, Nagarajesh
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Delay Impact on Gaming Experience, For a First Person Shooter Game.2009Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    The growing market for online games and their significant share in the internet traffic has allured researchers to investigate the factors affecting the game playing experience of the end user. In this work an investigation has been done on how one-way delay affects the First Person Shooter game there by Quality of Experience of the player. The data that is analyzed was collected at Dream Hack Winter-2007 by Telecommunications research team of Blekinge Institute of Technology, Sweden. It consisted of 57 experiments conducted using Battle-Field2 game in a controlled LAN, with between 2 and 4 players. The network was monitored using Distributed Passive Measurement Infrastructure. This thesis implemented tools to generate accurate delay plots for each relevant stream in the captured game traffic traces. The delay plots have been ensured by identifying what IP that was disturbed and when the disturbance occurred in the trace, as per the shaper settings. Then the investigation is mainly concentrated on the analysis of one-way delay and how it affects the end-user Quality of Experience. As a part of this work we also looked at the affect of packet delay variation on end user's perception, delay distribution of the shaper and packet length distribution of the client - server and server - client packets. Conclusions were made by stating that one-way delay and packet delay variation has considerable impact on end users perception. It is found that the delay of 400 ms is threshold delay value to get a good user response and packet delay variations of 100 ms and 200 ms with variable amounts of delay are detectable by the player.

  • 431.
    Garapati, Nagarajesh
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Quality Estimation of YouTube Video Service2010Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    YouTube is today one of the most popular video sharing web sites. It is using Flash Player technology together with progressive download to deliver videos in a variety of qualities adaptable to the clients connection speed and requirements. Recently YouTube has got much more user attention with the introduction of HD (High Definition) video content on its web site. This work started with analyzing different aspects of YouTube videos and finding a way to detect re-buffering events during playback. In an effort to do this, 38 videos were uploaded to YouTube and analyzed with respect to codec, container format, encoded bitrate and resolution. An application called YouTube Player API was used to detect the re-buffering events and some more useful information for the investigation. The greater part of the work concentrated on estimating the effect of re-buffering on the end user perceived quality of YouTube videos. Finally, conclusions were made by presenting a way to estimate the effect of re-buffering on the perceptual quality of YouTube videos and stating that the maximum quality available on YouTube for HD-720P and HD-1080P is approx 3.91 and 3.86 (on a scale from 1 to 5) respectively.

  • 432.
    Garlapati, Naveen
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Mohammed, Altaf Ahmed
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Evaluation of Power Conservation Algorithms in Industrial Wireless Sensor Networks2012Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Sensors play a prominent role in the industrialized society of today and a world without sensors is inconceivable as most of the electronic applications are based on it. Various applications including in the fields like military control in battlefield surveillance, industrial automation, health monitoring, security systems and many more utilizes wireless sensors, which reveals its prominence and deployment perspective. Such sensor nodes are becoming more common as the technology for wireless communication is becoming increasingly affordable. This thesis deals with the estimation of battery life for the selected algorithms where a specific industrial application is considered, utilizing wireless battery powered sensor nodes in order to measure indoor temperature in buildings as part of a heating control system. This application can accommodate only two batteries and sometimes it is to be placed in highly restricted areas, which makes it difficult to replace the batteries often. Hence saving the battery life is an intrinsic issue which needs to be overcome by any industrial manufacturer. So far, various algorithms have been implemented to solve this issue but have not succeeded completely. In our research we introduced a new approach to choose the best suited algorithm based on the requirements of specific industrial application. Also, by implementing those algorithms and considering the time interval of 15, 30 and 60 min, the battery life is estimated for any network. The purpose of the paper is to study and compare different power conservation algorithms for wireless sensor networks in relation to the specific constraints found in this heating control system. The different algorithms are evaluated on the basis of their ability to preserve power while simultaneously fulfilling these specific constraints. Three different algorithms are selected and studied through simulations and their individual operational behavior in relation to the specific industrial application is shown. Finally, this report demonstrates the total energy consumed per message, average distance calculations from source node to sink node, by performing simulations in MATLAB (v7.9.0). This paper also exhibits the behavior of PEGASIS, EEAR and SPIN-1 algorithms considering node number variation, node range and different communication intervals as parameters. By performing quantitative analysis of obtained results, at the end one can find the sustainability of the battery life. For 200 nodes network, it is lasting longer when PEGASIS algorithm (high energy efficient) is used. But for the same number of deployed nodes, the EEAR based network sustains smaller than PEGASIS based network (considering two batteries) as EEAR could accomplish self organizing technique, similarly SPIN-1 based networks lasts very small as they could implement both self organizing and self-healing techniques. Hence it is to conclude that, for this specific industrial application, the researchers as well as manufacturers can incorporate these results directly in their application.

  • 433.
    GESSESE, Mengistu
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    OLADELE, Olayinka
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    PERFORMANCE EVALUATION OF LTE DOWNLINK WITH MIMO TECHNIQUES2010Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Long Term Evolution (LTE) of the Universal Mobile Telecommunication System (UMTS) also known as the Evolved Packet System (EPS) is a transilient move in the field of mobile communications. Such a revolution is necessitated by the unceasing increase in demand for high speed connections on networks, low latency and delay, low error rates and resilience because modern users and network applications have become increasingly dependent on these requirements for efficient functionality and performance. Third Generation Partnership Project Long Term Evolution (3GPP LTE) promises high peak data rates for both uplink and downlink transmission, spectral efficiency, low delay and latency, low bit error rates, to mention but a few. These functional and performance targets of 3GPP LTE are laudable and can be met with a great measure of certainty, but then a vital question emerges: What are the prime drivers or enablers for these technology standard requirements to be met? LTE leverages on a number of technologies namely Multi Input Multiple Output (MIMO) antennas, Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Division Multiplexing Access (OFDMA) at the downlink, Single Carrier Frequency Division Multiple Access (SCFDMA) at the uplink, support for Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (16QAM), and 64QAM. This thesis work evaluates the performance of LTE downlink with MIMO techniques. MIMO technology involves the use of multiple antennas at the transmitter, receiver or both. There are different combinations of array configuration and polarization, transmission and detection schemes that can be implemented to achieve different purposes in functional and performance terms. In terms of array configuration and polarization, there exists single polarized array and cross polarized array (which could be compact or detached); transmission schemes include diversity schemes particularly transmit diversity and spatial multiplexing; detection schemes such as Zero Forcing (ZF) and Soft Sphere Decoding (SSD). The performance metrics considered are throughput and BER and these are used to evaluate the performance of LTE in flat-fading and International Telecommunications Union B (ITU-B) Pedestrian channel with zero forcing and soft sphere decoding for Single Input Single Output (SISO), transmit diversity and spatial multiplexing. The granular analysis and evaluation of the performance 3GPP LTE is imperative and this thesis implements this on the downlink side. A thorough analysis and performance evaluation of the LTE downlink with MIMO antennas is thus the focal point and the results demonstrate that the design goals and requirements of 3GPP LTE can be met with a great deal of reliability and certainty. The simulations show that the performance of MIMO is better than SISO in both channel models particularly when SSD is employed. When high order modulation is utilized, performance in the flat-fading channel model is better than ITU pedestrian B channel at low SNR regions. Spatial multiplexing is ideal for achieving very high peak rates, while transmit diversity is a valuable scheme to minimize the rate of bit error occurrence thereby improving signal quality.

  • 434.
    Ghadami, Soheil
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    The Evaluation of the Gaussian Mixture Probability Hypothesis Density Filter Applied in a Stereo Vision System2011Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    In this thesis, the performance of the Gaussian Mixture Probability Hypothesis Density (GM-PHD) filter using a pair of stereo vision system to overcome label discontinuity and robust tracking in an Intelligent Vision Agent System (IVAS) is evaluated. This filter is widely used in multiple-target tracking applications such as surveillance, human tracking, radar, and etc. A pair of cameras is used to get the left and right image sequences in order to extract 3-D coordinates of targets’ positions in the real world scene. The 3-D trajectories of targets are tracked by GM-PHD filter. Many tracking algorithms fail to simultaneously maintain stability of tracking and label continuity of targets, when one or more targets are hidden for a while to camera’s view. The GM-PHD filter performs well in tracking multiple targets; however, the label continuity is not maintained satisfactorily in some situations such as full occlusion and crossing targets. In this project, the label continuity of targets is guaranteed by a new method of labeling, and the simulation results show satisfactory results. A random walk motion is used to validate the ability of the algorithm in tracking and maintaining targets’ labels. In order to evaluate the performance of the GM-PHD filter, a 3-D spatial test motion model is introduced. Here, the two target trajectories are generated in a way that either occlusion or crossing occurs in some time intervals. Then, the two key parameters, angular velocity and motion speed, are used to evaluate the performance of algorithm. The simulation results for two moving targets in occlusion and crossing show that the proposed system not only robustly tracks them, but also maintains the label continuity of two targets.

  • 435.
    Ghandchi, Bahram
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Saleh, Taha
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Indoor Mobile Positioning system (MPS) classification in different wireless technology domain2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The main purpose of this thesis work is to find and compare different network characteristics of MPS (Mobile Positioning System) in the different wireless technology domains. Since decades ago MNO’s (Mobile Network Operators) added many new services based on the geographical areas of subscribers and their needs. Here we define wireless networks and go through different types of technologies and do the comparison when they collect different types of data for their location-based services and see if we could have the same accuracy with 2G (second generation) of mobile network as like as 3G (third generation) and higher. Finally, we will come up with a proposal for new age technology.

  • 436.
    Gharari, Farnaz
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Performance Analysis of Piecewise-and-Forward Relay Network on Rayleigh Fading Channel2015Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    The rapid changes and developments in cellular and wireless networks aim to provide more reliable communications with high data rate transmission. So far, one solution which is being considered for improving the reliability and eciency of mobile communications is cooperative communications. Implementing di fferent relay scenarios leads to the improvement of the security, ecient, and fast transmission with a good quality of service. The work of this thesis is on the piecewise-and-forward (PF) relay network. This relay protocol is implemented for decreasing the complexity of signal detection at the receiver. Our focus is to investigate the performance of PF relay networks based on the statistical variations which are caused by the fading environment. We considered a relay network with one source and one destination while multiple parallel relays aid the transmission process. At the destination the maximum likelihood (ML) method is implemented for detecting the received signals. Therefore, the probability density function (PDF) of received signals should be used at the ML detector. We analytically investigate the PDF of the received signals, when the transmitted signals are faced with Rayleigh fading. For verifying the theoretical calculations, we use Monte-Carlo simulations in MATLAB to evaluate the results. Afterwards, the bit error rate (BER) has been considered for investigating the performance of the PF relay network over a Rayleigh fading channel. Furthermore, the BER performance of the PF relay network is compared with three well known relay networks, amplify-and-forward (AF), decode-and forward (DF), and estimate-and-forward (EF) relay networks.

  • 437.
    Gholamzadeh Shirmohammadi, Bamshad
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Relationships between Quality of experience and TCP flag ratios for web services2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Context: Nowadays one of the most beneficial business in IT area is web services with huge amount of users. The key ofsuccess in these type of services is flexibility in terms of providing same quality of services (QoS) and ability of fasttroubleshooting when number of users increase rapidly. To achieve these targets, evaluation of the user satisfaction is highlyessential. Moreover it is required to link user dissatisfaction to QoS parameters in terms of troubleshooting.

    Objectives: The main aim the research is to find an intelligent method for evaluation of the user satisfaction. The method isproposed to estimate quality-of-experience (QoE) without asking users to send their feed back. Connecting to this aim, thesecond target is finding the definition of function in equations of QoS=function(QoE). And finally, comparison of theimpact of QoS parameters on mobile application users and web site users is the last objective.

    Methods: For this research a web-server for video sharing propose is designed. The users can use it via web site or anAndroid mobile application. The three main QoS parameters (Packet-loss, delay and throughput) are changed gradually. Theusers are asked to score the mobile application and web site at the same time. In parallel the traffic of web-server is capturedand analyzed. Then based on variations in mean opinion scores (MOS) and also changes in TCP flags, the proper patternsfor each of the QoS parameters is provided. In this part the QoE is linked to transport layer. For the second objective, theQoE is directly linked to QoS. On the other words the graphs with QoE as horizontal axis and one of the QoS parameters asvertical axis are provided. And finally based on the gradient of these trends, the amount of impact of QoS parameters onmobile application users and web site users is compared.

    Results: Based on the results of the research, decrement in SYN and FIN flags and increment in ACK is an alarm for downgoing user satisfaction. In this situation, the problem is belongs to packet-loss. Increasing in the percentage of SYN is alsoa signal for user dissatisfaction. In this case, the problem is result of delay. And finally if the web-server problem is aboutthroughput then, SYN, FIN and ACK has up going trends. In all of the cases the rest of TCP flags has not clear up going ordecreasing trend.The correlation between QoS and QoE is formulated. The trends of MOS relative to QoS parameters for mobile phone andlaptop are very similar in case of packet-loss. For throughput the mobile phone users are a little more sensitive. The mostsignificant difference between the MOS values for mobile application and web site is belongs to delay. The increment indelay has really big negative effect on mobile application users.

    Conclusion: The final method for user satisfaction evaluation is based on the way of variations in the TCP flags. Among allthe flags, SYN, FIN and ACK passed the criteria to make the patterns. Moreover the method indicate the problem isbelongs to which of the QoS parameters. The correlation between QoE and QoS is formulated. And finally according tothese formulas, two separate web-servers for mobile application and web site is recommended.

  • 438.
    Gillani, Syed Fakhar Uz Zaman
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Investigation of End User IPTV Quality for Content Delivered in MPEG-2 Transport Stream2010Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    IPTV or Internet Protocol Television is a system where digital television is delivered to the end user using the Internet Protocol. It relies on the same technologies that are used for computer networks and adds new possibilities, such as video on demand, on top of the traditionally broadcasted TV. Video content for IPTV is typically compressed using a MPEG-2 or H.264 (MPEG-4 part 10) compression and sent in an MPEG-2 transport stream over IP. Since TV is a "real time service" packets are delivered using a simple unreliable transmission model and packets may arrive out of order or be lost. Lost packets are normally not re-transmitted since they anyhow would arrive too late to be useful and packet loss will thus decrease perceived quality for the end user. The Master thesis is an investigation of the parameters that affect the perceived quality in MPEG-2 Transport Stream (TS). The aim of the thesis is to develop an objective parametric model1 that can estimate the perceived quality at transport layer. The thesis work includes experimentation performed on High Definition (HD) video sequences with various bit rates and packet loss ratios (PLR).

  • 439.
    Ginka, Anusha
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Salapu, Venkata Satya Sameer
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datavetenskap.
    Optimization of Packet Throughput in Docker Containers2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Container technology has gained popularity in recent years, mainly because it enables a fast and easy way to package, distribute and deploy applications and services. Latency and throughput have a high impact on user satisfaction in many real-time, critical and large-scale online services. Although the use of microservices architecture in cloud-native applications has enabled advantages in terms of application resilience, scalability, fast software delivery and the use of minimal resources, the packet processing rates are not correspondingly higher. This is mainly due to the overhead imposed by the design and architecture of the network stack. Packet processing rates can be improved by making changes to the network stack and without necessarily adding more powerful hardware.

    In this research, a study of various high-speed packet processing frameworks is presented and a software high-speed packet I/O solution i.e., as hardware agnostic as possible to improve the packet throughput in container technology is identified. The proposed solution is identified based on if the solution involves making changes to the underlying hardware or not. The proposed solution is then evaluated in terms of packet throughput for different container networking modes. A comparison of the proposed solution with a simple UDP client-server application is also presented for different container networking modes. From the results obtained, it is concluded that packet mmap client-server application has higher performance when compared with simple UDP client-server application.

  • 440.
    Godavarthi, Nandini Chowdary
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Power Consumption Models for Streaming on Mobile Terminals with On-Off Characteristics2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The usage of smartphones has been increasing with surprising speed. These smartphones are popular for delivery of video content. The main drawbacks of these smartphones are battery life and video freezing. Despite, while streaming a video it consumes large of amount of power affecting QoE. So, in this case we considered streaming a video from server to mobile client involving ONOFF characteristics. While streaming, there exists some transition delay while switching the power states and the effect of these transition delays might affect instantaneous power consumption of the smartphone.

    Henceforth, this thesis aims to determine the effect on instantaneous power consumption from distributed state durations and transitions in exponential fluid flow model, for a streamed video. Power measurements along with ON and OFF times were measured with the help of a benchmark tool, Monsoon Power Monitor tool. VLQoE tool, a video streaming tool was used to present a two state model based on the inter-picture time, for the HTTP-based video streaming. Experiments were executed in a closed enclosure setup using a black-box to avoid external obstacles that might possibly affect the power consumption metrics. Considering these measurements, the effect on instantaneous power consumption stemming from the exponentially distributed state durations and transitions in the corresponding fluid flow model can be determined and modelled. 

  • 441.
    Gopalakrishna, Abhijith
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Capacity Analysis of Cognitive Radio Relay Networks under Transmission and Interference Power Constraints2012Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    This thesis investigates the performance of cognitive radio relay networks (CRRN) in Rayleigh fading channel under various power constraints. Here spectrum sharing approach is considered, whereby a secondary user (SU) may be allowed to transmit simultaneously with a primary user (PU) as long as SU interference to PU remains below a tolerable level. In addition, SU has to meet certain quality of service (QoS) constraints of its own link. To support these QoS constraints, the maximal data rate that can be reliably transmitted with arbitrarily small error of probability is found. It is observed that this capacity is affected by channel quality and interference limit allowed by PU. Ergodic capacity and outage capacity which are two well known capacities, are analysed for CRRN under interference power constraints. This thesis also finds effective capacity for CRRN, a link layer channel model that models the effect of channel fading on queuing behaviour of the link. Effective capacity under interference and secondary transmitter power constraints is also investigated. The way of analysing effective capacity under interference and transmit power constraints is extended to ergodic capacity and outage capacity. Here it is observed that, capacity is affected by the minimum of transmit power and interference power constraints. Monte-Carlo simulations are carried out to support theoretical results obtained in this thesis.

  • 442.
    Gopalakrishna, Abhijith
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Ha, Dac Binh
    Capacity Analysis of Cognitive Radio Relay Networks with Interference Power Constraints in Fading channels2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper investigates the performance of cognitive radio relay networks with interference power constraints in Rayleigh fading channel. Here we consider spectrum sharing approach, whereby secondary user (SU) may be allowed to transmit simultaneously with primary user (PU) as long as its interference to the PU remains below tolerable level. In addition, SU has to meet certain Quality of Service (QoS) constraints of its own link. To support this QoS constraint, what is the maximal data rate that can be reliably transmitted with arbitrarily small error of probability is found. We observe that this capacity is affected by channel quality of secondary transmission links as well as the interference limit allowed from primary user. Close form expression for effective capacity considering delay as a QoS constraint is derived and simulation results are provided to support theoretical results. The approach of finding effective capacity is extended to outage capacity and ergodic capacity in delay insensitive applications.

  • 443.
    Grandhi, Veera Venkata Santosh Surya Ganesh
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    On the Quality of Service of mobile cloud gaming using GamingAnywhere2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In the recent years, the mobile gaming has been tremendously increased because of its enormous entertainment features. Mobile cloud gaming is a promising technology that overcomes the implicit restrictions such as computational capacity and limited battery life. GamingAnywhere is an open source cloud gaming system which is used in this thesis to measure the Quality of service of mobile cloud gaming. The aim of the thesis is to measure the QoS used in GamingAnywhere for mobile cloud gaming. Games are streamed from the server to the mobile client. In our study, QoS is measured using Differentiated Service (DiffServ) architecture for the traffic shaping. The research method is carried out using an experimental testbed. Dummynet is used for traffic shaping. Performance is measured in terms of bitrate, packet loss, jitter, and frame rate. Different resolutions of the game are considered in our empirical research and our results show that the framerate and bitrate have increased with the impact of network delay.

  • 444. Grbic, Nedelko
    et al.
    Nordholm, Sven
    Nordberg, Jörgen
    Claesson, Ingvar
    A New Pilot-Signal based Space-Time Adaptive Algorithm2001Konferensbidrag (Refereegranskat)
    Abstract [sv]

    En ny adaptiv algoritm presenteras för smart antennas. Fördelen med algoritmen är att även perioder i förbindelsen där utsänd signal är okänd, utförs en blind adaption av kanalutjämning/beamforming.

  • 445. Griffiths, Wayne
    et al.
    Zepernick, Hans-Jürgen
    Caldera, Manora
    APP Decoding of Binary Linear Block Codes on Gilbert-Elliott Channels2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, a mathematical framework for APP decoding of binary linear block codes on the Gilbert-Elliott channel (GEC) is developed. For this purpose, the theory of group representations and finite state machines are combined for deriving a `dual APP' algorithm for the GEC. The presented approach belongs to the class of single-sweep algorithms. As such, complexity benefits of the dual approaches are preserved while additional storage savings are obtained over other single-sweep algorithms. The presented APP decoding technique also takes account of the increasing demand for efficient utilization of bandwidth making higher rate codes more desirable.

  • 446. Griffiths, Wayne
    et al.
    Zepernick, Hans-Jürgen
    Caldera, Manora
    APP Decoding of Block Codes Over Gilbert-Elliott Channels Using Generalized Weight Polynomials2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present an a posteriori probability (APP) decoding algorithm for binary linear block codes over a Gilbert- Elliott channel (GEC) using generalized weight polynomials. The proposed approach is based on a single-sweep APP decoding technique that uses matrix multiplications. By fixing the crossover probability in the ‘bad’ state of the GEC at fifty percent, an APP decoding decision can be reached by evaluating trivariate polynomials without the need for the computationally more expensive matrix multiplications. In this case, the GEC is described by three variables, namely, the average fade to average connection time ratio, the burst factor, and the channel reliability factor. These variables can easily be deduced from error sequence measurements and hence can be related to many practical digital communication scenarios. The polynomial approach is demonstrated using a simple example and results of computer simulations are presented.

  • 447. Griffiths, Wayne
    et al.
    Zepernick, Hans-Jürgen
    Caldera, Manora
    APP Decoding of Block Codes Over Prime Fields on Non-Binary Gilbert-Elliott Channels2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present an a-posteriori probability (APP) decoding algorithm for linear block codes over prime fields when used on non-binary Gilbert-Elliott channels (GECs). The proposed approach is based on a single-sweep APP decoding technique that uses matrix multiplications. The trellis-based decoding algorithm incorporates the channel-induced error process by modeling it as a stochastic automaton. It is applicable to high rate block codes over prime fields on channels with memory such as the non-binary GEC. It allows simple implementation in the spectral domain.

  • 448. Griffiths, Wayne
    et al.
    Zepernick, Hans-Jürgen
    Caldera, Manora
    APP Decoding of Non-Binary Block Codes on Gilbert-Elliott Channels Using Generalized Weight Polynomials2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we present an a-posteriori probability (APP) decoding algorithm for non-binary block codes on non-binary Gilbert-Elliott channels (GECs) using generalized weight polynomials. The proposed approach is based on a single-sweep APP decoding technique that utilizes matrix multiplications. By fixing the crossover probability in the `bad' state of the non-binary GEC such that for a given transmitted symbol, all symbols are equally likely to be received, an APP decoding decision can efficiently be reached by evaluating trivariate polynomials. In this case, the non-binary GEC is described by three variables that are referred to as the average fade to connection time ratio, the burst factor, and the channel reliability factor. The application of the generalized weight polynomial approach is demonstrated with respect to numerical performance results obtained for simple non-binary block codes from computer simulations.

  • 449. Griffiths, Wayne
    et al.
    Zepernick, Hans-Jürgen
    Caldera, Manora
    On APP Decoding of Non-Binary Block Turbo Codes over Discrete Channels2004Konferensbidrag (Refereegranskat)
  • 450.
    Guduru, Manish Reddy
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Investigating the effects of load on the XIFI node2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Having a good understanding of the load requirements in the datacenter improves the capability to effectively provision the resources available to the meet the demands and objectives of application services. Especially in a large project like XIFI this aspect becomes even more critical because of the limited availability of the resources and the complexity of the various entities present.In this study we frame a structure that provides deep insights to comprehend XIFI infrastructure. Further, we model the user requests that approach the node for resource allocation to run their applications. We aim to provide an understanding on different aspects involved in modelling. The objective of this present study is to investigate the effect of load on the XIFI node. To achieve this objective, we model the XIFI node by examining the various entities involved in it. Furthermore, we provide an overview about what constitutes as load in the XIFI node.We conduct a detailed specifications study after which we identify the imperative entities required for the modelling of both the XIFI node and the requests. We examine the model by simulating it in CloudSim for two different scenarios varying the specifications.We simulated the designed structure for 30 iterations and analyzed 10,000 user requests for two cases where total RAM of the node is increased in the second case when compared to the first case. We analyze the CPU usage, RAM usage, Bandwidth usage and Storage usage in both the cases and examine the effects of the user requests on each one of them.The results provided evidence that the load indices on the host are dependent on each other. Also, it showed that the request modelling had an impact on the load of the host. It can also be concluded that the resource provisioning can be effective if the user behavior is known.

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