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  • 3001.
    Yu, Lizhen
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Handelshögskolan (from 2013).
    How information sharing still can help in the semiconductor Supply Chain2023Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The semiconductor industry is facing a serious capacity shortage, where deliveries of semiconductor products are suffering heavily from this crisis. The pandemic has added additional challenges to an already difficult situation. The purpose of thesis is to investigate how information sharing in the semiconductor Supply Chain can help the challenges in the semiconductor industry.

    This thesis about information sharing in the semiconductor supply chain is using a qualitative method, and an analysis is done by using a literature review and a literature survey. The literature review is about Supply Chain management, supply chain network, actors, flows, supply chain integration, Supply Chain models, information sharing, and the benefits of Supply Chain information sharing. The literature survey is an in-depth study to understand the semiconductor Supply Chain situation and the challenges. The literature review is used to analyze the challenges, and then to find out how information sharing would help semiconductor Supply Chains.

    Three Supply Chain challenges could be found, and those are: “The global logistics network of suppliers”, “A wide and increasing demand”, and “Capacity and lead time”. Information sharing can help to decrease all the 3 Supply Chain challenges in the semiconductor industry and improve the situation. This thesis show that information sharing can help but may not be helping fully because of the difficult capacity situation. Supply Chains are of course different to each other, and information sharing could be more effective in some Supply Chains than others.

  • 3002. Yusupov, Roman
    et al.
    Artan, Stefan
    Domain Specific Test Language2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

        Testing is an important part of software development. It ensures that the developed product is of high standard and quality. Tieto frequently develops large complex systems which require comprehensive testing. Testing employs manually designed test cases. According to recent development within software testing it has been shown that design of test cases can be simplified with domain specific test languages (DSTL).

        The thesis project is a research and development study in the field of software testing and has been performed at Tieto office in Karlstad. The project concerns the development of a DSTL and a suitable development environment based on the Eclipse Platform. The project evaluates the development of a domain specific test language using the tools Eclipse JDT, developed by Eclipse Foundation, and Xtext, developed by itemis AG. The experiment was evaluated by its functionality and integrability.

        The project has shown promise in using a domain specific test language with a suitable development environment. The result and evaluation have shown that the subject shows promise, but needs further development if it is to be adapted within Tieto´s organization.

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    DomainSpecificTestLanguage
  • 3003.
    Zamli, K. Z.
    et al.
    Universiti Malaysia Pahang, MYS.
    Din, F.
    Universiti Malaysia Pahang, MYS; University of Malakand, PAK.
    Ramli, N.
    Universiti Teknologi MARA Pahang, MYS.
    Ahmed, Bestoun S.
    Software module clustering based on the fuzzy adaptive teaching learning based optimization algorithm2019Ingår i: Lecture Notes in Networks and Systems, Springer , 2019, s. 167-177Konferensbidrag (Refereegranskat)
    Abstract [en]

    Although showing competitive performances in many real-world optimization problems, Teaching Learning based Optimization Algorithm (TLBO) has been criticized for having poor control on exploration and exploitation. Addressing these issues, a new variant of TLBO called Adaptive Fuzzy Teaching Learning based Optimization (ATLBO) has been developed in the literature. This paper describes the adoption of Fuzzy Adaptive Fuzzy Teaching Learning based Optimization (ATLBO) for software module clustering problem. Comparative studies with the original Teaching Learning based Optimization (TLBO) and other Fuzzy TLBO variant demonstrate that ATLBO gives superior performance owing to its adaptive selection of search operators based on the need of the current search. © Springer Nature Singapore Pte Ltd. 2019.

  • 3004.
    Zamli, K. Z.
    et al.
    Universiti Malaysia Pahang, MYS.
    Kader, M. A.
    Universiti Malaysia Pahang, MYS.
    Azad, S.
    Universiti Malaysia Pahang, MYS.
    Ahmed, Bestoun S.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Hybrid Henry gas solubility optimization algorithm with dynamic cluster-to-algorithm mapping2021Ingår i: Neural Computing & Applications, ISSN 0941-0643, E-ISSN 1433-3058, Vol. 33, s. 8389-8416Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper discusses a new variant of Henry Gas Solubility Optimization (HGSO) Algorithm, called Hybrid HGSO (HHGSO). Unlike its predecessor, HHGSO allows multiple clusters serving different individual meta-heuristic algorithms (i.e., with its own defined parameters and local best) to coexist within the same population. Exploiting the dynamic cluster-to-algorithm mapping via penalized and reward model with adaptive switching factor, HHGSO offers a novel approach for meta-heuristic hybridization consisting of Jaya Algorithm, Sooty Tern Optimization Algorithm, Butterfly Optimization Algorithm, and Owl Search Algorithm, respectively. The acquired results from the selected two case studies (i.e., involving team formation problem and combinatorial test suite generation) indicate that the hybridization has notably improved the performance of HGSO and gives superior performance against other competing meta-heuristic and hyper-heuristic algorithms.

  • 3005.
    Zamli, Kamal Z.
    et al.
    Universiti Malaysia Pahang, MYS.
    Alsewari, Abdulrahman
    Universiti Malaysia Pahang, MYS.
    Ahmed, Bestoun S.
    Czech Technical University, CZE.
    Multi-Start Jaya Algorithm for Software Module Clustering Problem2018Ingår i: Azerbaijan Journal of High Performance Computing, Vol. 1, nr 1, s. 87-112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Jaya algorithm has gained considerable attention lately due to its simplicity and requiring no control parameters (i.e. parameter free). Despite its potential, Jaya algorithm is inherently designed for single objective problems. Additionally, Jaya is limited by the intense conflict between exploration (i.e. roams the random search space at the global scale) and exploitation (i.e. neighborhood search by exploiting the current good solution). Thus, Jaya requires better control for exploitation and exploration in order to prevent premature convergence and avoid being trapped in local optima. Addressing these issues, this paper proposes a new multi-objective Jaya variant with a multi-start adaptive capability and Cuckoo search like elitism scheme, called MS-Jaya, to enhance its exploitation and exploration allowing good convergence while permitting more diverse solutions. To assess its performances, we adopt MS-Jaya for the software module clustering problem. Experimental results reveal that MS-Jaya exhibits competitive performances against the original Jaya and state-of-the-art parameter free meta-heuristic counterparts consisting of Teaching Learning based Optimization (TLBO), Global Neighborhood Algorithm (GNA), Symbiotic Optimization Search (SOS), and Sine Cosine Algorithm (SCA).

  • 3006.
    Zamli, Kamal Z.
    et al.
    University Malaysia Pahang Lebuhraya, MYS.
    Din, Fakhrud
    University Malaysia Pahang Lebuhraya, MYS.
    Ahmed, Bestoun S.
    Czech Technical University, CZE.
    Bures, Miroslav
    Czech Technical University, CZE.
    A hybrid Q-learning sine-cosine-based strategy for addressing the combinatorial test suite minimization problem2018Ingår i: PLOS ONE, E-ISSN 1932-6203, Vol. 13, nr 5, artikel-id e0195675Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The sine-cosine algorithm (SCA) is a new population-based meta-heuristic algorithm. In addition to exploiting sine and cosine functions to perform local and global searches (hence the name sine-cosine), the SCA introduces several random and adaptive parameters to facilitate the search process. Although it shows promising results, the search process of the SCA is vulnerable to local minima/maxima due to the adoption of a fixed switch probability and the bounded magnitude of the sine and cosine functions (from -1 to 1). In this paper, we propose a new hybrid Q-learning sine-cosine- based strategy, called the Q-learning sinecosine algorithm (QLSCA). Within the QLSCA, we eliminate the switching probability. Instead, we rely on the Q-learning algorithm (based on the penalty and reward mechanism) to dynamically identify the best operation during runtime. Additionally, we integrate two new operations (Levy flight motion and crossover) into the QLSCA to facilitate jumping out of local minima/maxima and enhance the solution diversity. To assess its performance, we adopt the QLSCA for the combinatorial test suite minimization problem. Experimental results reveal that the QLSCA is statistically superior with regard to test suite size reduction compared to recent state-of-the-art strategies, including the original SCA, the particle swarm test generator (PSTG), adaptive particle swarm optimization (APSO) and the cuckoo search strategy (CS) at the 95% confidence level. However, concerning the comparison with discrete particle swarm optimization (DPSO), there is no significant difference in performance at the 95% confidence level. On a positive note, the QLSCA statistically outperforms the DPSO in certain configurations at the 90% confidence level.

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  • 3007.
    Zamli, Kamal Z.
    et al.
    University Malaysia Pahang, MYS.
    Din, Fakhrud
    University Malaysia Pahang, MYS.
    Baharom, Salmi
    University Putra, MYS.
    Ahmed, Bestoun S.
    Czech Technical University, CZE.
    Fuzzy adaptive teaching learning-based optimization strategy for the problem of generating mixed strength t-way test suites2017Ingår i: Engineering applications of artificial intelligence, ISSN 0952-1976, E-ISSN 1873-6769, Vol. 59, s. 35-50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The teaching learning-based optimization (TLBO) algorithm has shown competitive performance in solving numerous real-world optimization problems. Nevertheless, this algorithm requires better control for exploitation and exploration to prevent premature convergence (i.e., trapped in local optima), as well as enhance solution diversity. Thus, this paper proposes a new TLBO variant based on Mamdani fuzzy inference system, called ATLBO, to permit adaptive selection of its global and local search operations. In order to assess its performances, we adopt ATLBO for the mixed strength t-way test generation problem. Experimental results reveal that ATLBO exhibits competitive performances against the original TLBO and other meta-heuristic counterparts.

  • 3008.
    Zamli, Kamal Z.
    et al.
    University Malaysia Pahang, MYS.
    Din, Fakhrud
    University Malaysia Pahang, MYS.
    Kendall, Graham
    University Nottingham, MYS.
    Ahmed, Bestoun S.
    Czech Technical University, CZE.
    An experimental study of hyper-heuristic selection and acceptance mechanism for combinatorial t-way test suite generation2017Ingår i: Information Sciences, ISSN 0020-0255, E-ISSN 1872-6291, Vol. 399, s. 121-153Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, many meta-heuristic algorithms have been proposed to serve as the basis of a t-way test generation strategy (where t indicates the interaction strength) including Genetic Algorithms (GA), Ant Colony Optimization (ACO), Simulated Annealing (SA), Cuckoo Search (CS), Particle Swarm Optimization (PSO), and Harmony Search (HS). Although useful, meta heuristic algorithms that make up these strategies often require specific domain knowledge in order to allow effective tuning before good quality solutions can be obtained. Hyper heuristics provide an alternative methodology to meta-heuristics which permit adaptive selection and/or generation of meta-heuristics automatically during the search process. This paper describes our experience with four hyper-heuristic selection and acceptance mechanisms namely Exponential Monte Carlo with counter (EMCQ), Choice Function (CF), Improvement Selection Rules (ISR), and newly developed Fuzzy Inference Selection (FIS), using the t-way test generation problem as a case study. Based on the experimental results, we offer insights on why each strategy differs in terms of its performance. (C) 2017 Elsevier Inc. All rights reserved.

  • 3009.
    Zarkovic, Dejan
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Handelshögskolan (from 2013).
    En e-konsuments kundresa: Fysiska omgivningens påverkan på e-kundresan mätt med hjälp av eye-tracking2024Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Uppsatsen har undersökt konsumenters kundresa på olika e-handels hemsidor. Syftet har varit att undersöka var i kundresan – före eller under köp – som kundupplevelsernaär som starkast. Både positiv och negativ kundupplevelse undersöks samt hur den fysiskaomgivningen, mer specifikt fysiska butiker, påverkar e-handelsupplevelsen. Ett syfte vardessutom att se hur eye-tracking fungerar som utvärderingsmetod med hjälp av intervjuer frånanställda på Karlstads universitet som undersökt kundresor tidigare i en fysisk miljö. Dettagenomfördes även genom att upprätta kundresekartor från användartester med hjälp av bådeeye-tracking och retrospektiv tänka högt. Eye-tracking tillsammans med Tänka-högt metodenanvändes för att få en bra bild av kundresan och de kundupplevelser som är förknippade med kundresan. För att undersöka hur fysiska affärer påverkar beteendet hos e-kunder användes eye-tracking med hjälp av en retrospektiv tänka högt och semistrukturerade intervjuer.

    Resultaten, när det gäller var kunder upplever köpen som starkast, var att den fysiska affären hade en viss påverkan på vilken affär testdeltagarna väljer. Eye-tracking som utvärderingsmetod för kundresor fungerar bra med hjälp av flera andra metoder, som retrospektiv tänka högt och intervjuer.

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  • 3010.
    Zarkovic, Stefan
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Handelshögskolan (from 2013).
    Utveckling av en interaktiv introduktion till en tvåspråkig parlör för krishanteringstermer2023Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Kriskommunikation kräver att alla inblandade förstår olika termer och ord som kan användas ien kris. När övningar äger rum på gränsen mellan Sverige och Norge kan vissa språkbarriäreruppstå. Därför har en parlör med kristermer och ord för de två språken tagits fram. Syftet medföreliggande studie är att skapa en webbaserad interaktiv introduktion till parlöranvändningsom kan hjälpa fackfolk att bekanta sig med parlörens uppläggning och sökmöjligheter. Arbetetgenomfördes som en designstudie med fokus på implementationsfasen eftersom innehåll ochinteraktionsdesignen var utvärderad i tidigare studier. Denna studie identifierar och belysersvårigheter som finns när man går från en design till implementation och hur man anpassar dedesignmönster som finns tillgängliga. Den interaktiva introduktionen finns upplagd påwww.criseit.org.

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  • 3011.
    Zebari, Blend
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Handelshögskolan (from 2013).
    Recommendations for maintaining data security when working remotely: Interviews with IT stakeholders post COVID-192022Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    With companies having recently transitioned into working from home, more so in the recent years due to the appearance of COVID-19, the need to restructure the processes, invest in newtechnology, and adapt the users to the new working environment is a must. Due to the existence of available technology and processes that can be used when working remotely but where there is a lack of qualitative interviews with companies regarding the usage aspect, this study will focus on conducting qualitative interviews with data security experts from IT companies regarding their knowledge over the data security issues their company has when working from home and the recommendations they can share to prevent these issues from appearing.There will be 5 semi-structured interviews conducted with data security experts from IT companies. Their perspectives regarding data security when working remotely will also be collected. The collected data will then be analyzed manually by using Thematic Analysis to reach an outcome for this study.By conducting the Thematic Analysis, 4 themes were found, namely User Vulnerability on Data Security, Company Key Priorities, Data Backup, and User Security Measures. With these themes, it was analyzed and concluded that there are companies that still lack awareness and experience regarding data security and even though recommendations were gained to achieve this study’s purpose, it was made evident that without proper experience or communication within a company regarding data security, preventing data security breaches from appearing when working remotely will become difficult.

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  • 3012.
    Zeljkovic, Ensar
    et al.
    Univ Antwerp, Belgium.
    Marquez-Barja, Johann M.
    Univ Antwerp, Belgium.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Riggio, Roberto
    FBK CREATE, NET, Italy.
    Latre, Steven
    Univ Antwerp, Belgium.
    Proactive Access Point Driven Handovers in IEEE 802.11 Networks2018Ingår i: 14th International Conference on Network and Service Management, CNSM 2018 / [ed] S. Salsano, R. Riggio, T. Ahmed, T. Samak, CRP. DosSantos, IEEE, 2018, s. 261-267Konferensbidrag (Refereegranskat)
    Abstract [en]

    In large and densely deployed IEEE 802.11 networks, a fast and seamless handover scheme is an important aspect in order to provide reliable connectivity for mobile users. However, IEEE 802.11 only supports decentralized, reactive and mobile node-driven handovers resulting in long handover times, packet loss due to interrupted connectivity and sub-optimal access point selection. Recently, centralized approaches have been developed that try to solve many of the challenges but these are mostly proprietary, reactive and require changes to mobile node stacks. In this paper, we propose a novel handover solution based on the principle of Software Defined Networking, that addresses the aforementioned challenges. Using virtualization and softwarization, we shift the traditional mobile node-driven handovers to the access point, while maintaining compliance with legacy devices. Moreover, we develop a proactive handover algorithm ADNA, which combines network state, traffic load and node mobility information. We evaluate our approach extensively in a testbed, showing that it outperforms existing approaches by improving the overall throughput by 116% while reducing the number of handovers by 44% on average.

  • 3013.
    Zhang, Ge
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    An analysis for anonymity and unlinkability for a VoIP conversation2009Ingår i: PRIVACY AND IDENTITY MANAGEMENT FOR LIFE, 2009, s. 198-212Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the growth of its popularity, more and more VoIP services are deployed in the Internet nowadays. Similarly to other Internet applications, VoIP users may desire to be unlinkable with their participated VoIP session records for privacy issues. In this paper, we explore the Items of Interests (IOIs) from anonymization aspects based on a simplified VoIP model and analyze the potential links between them. We address possible methods to break the links. Finally, we also discuss requirements for a VoIP Anonymization Service (VAS)

  • 3014.
    Zhang, Ge
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Towards Secure SIP Signalling Service for VoIP applications: Performance-related Attacks and Preventions2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Current Voice over IP (VoIP) services are regarded less secure than the traditional public switched telephone network (PSTN). This is due to the fact that VoIP services are frequently deployed in an relatively open environment so that VoIP infrastructures can be easily accessed by potential attackers. Furthermore, current VoIP services heavily rely on other public Internet infrastructures shared with other applications. Thus, the vulnerabilities of these Internet infrastructures can affect VoIP applications as well. Nevertheless, deployed in a closed environment with independent protocols, PSTN has never faced similar risks.

    The main goal of this licentiate thesis is the discussion of security issues of the Session Initiation Protocol (SIP), which serves as a signalling protocol for VoIP services. This work especially concentrates on the security risks of SIP related to performance. These risks can be exploited by attackers in two ways: either actively or passively. The throughput of a SIP proxy can be actively manipulated by attackers to reduce the availability of services. It is defined as Denial of Service (DoS) attacks. On the other hand, attackers can also profile confidential information of services (e.g., calling history) by passively observing the performance of a SIP proxy. It is defined as a timing attack. In this thesis, we carefully studied four concrete vulnerabilities existing in current SIP services, among which, three of them can lead to DoS attacks and one can be exploited for timing attacks. The results of our experiments demonstrate that these attacks can be launched easily in the real applications.

    Moreover, this thesis discusses different countermeasure solutions for the attacks respectively. The defending solutions have all in common that they are influencing the performance, by either enhancing the performance of the victim during a DoS attack, or abating the performance to obscure the time characteristic for a timing attack. Finally, we carefully evaluated these solutions with theoretical analyses and concrete experiments.

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    FULLTEXT02
  • 3015.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Berthold, Stefan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Hidden VoIP Calling Records from Networking Intermediaries2010Konferensbidrag (Refereegranskat)
    Abstract

    While confidentiality of telephone conversation contents has recently received considerable attention in Internet telephony (VoIP), the protection of the caller--callee relation is largely unexplored. From the privacy research community we learn that this relation can be protected by Chaum's mixes. In early proposals of mix networks, however, it was reasonable to assume that high latency is acceptable. While the general idea has been deployed for low latency networks as well, important security measures had to be dropped for achieving performance. The result is protection against a considerably weaker adversary model in exchange for usability. In this paper, we show that it is unjustified to conclude that low latency network applications imply weak protection. On the contrary, we argue that current Internet telephony protocols provide a range of promising preconditions for adopting anonymity services with security properties similar to those of high latency anonymity networks. We expect that implementing anonymity services becomes a major challenge as customer privacy becomes one of the most important secondary goals in any (commercial) Internet application.

  • 3016.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Cheng, Feng
    Meinel, Christoph
    SIMPA: A SIP-based Mobile Payment Architecture2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    In recent years, many mobile payment (MP) schemes have been proposed and used in practise. However, a prerequisite for extended acceptance and adoption of MP technologies is to deploy an effective MP system. So far, there is no such a standardised and scalable MP platform. Most current MP schemes are circumscribed by its mobile network infrastructures. Fortunately, the fast advancement of 3G technology equips next generation mobile phone network more benefits. Following this direction, we propose SIMPA - A SIP-based Mobile Payment Architecture for next generation mobile network, which not only supports P2P payment communications between customers and merchants using Session Initiation Protocol (SIP), but also supports several traditional Internet security protocols, to enhance privacy, confidentiality and integrity during the transaction. This paper depicts detailed protocol and system architecture of SIMPA. Some application examples from customers' view are shown to demonstrate its function and feature

  • 3017.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Cheng, Feng
    Meinel, Christoph
    Towards Secure Mobile Payment Based on SIP2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    Mobile payment has some unique advantages over more traditional payment methods in, for example, TV shopping and mobile multimedia services. Unfortunately, most existing mobile payment solutions rely heavily on underlying communication infrastructures, which are platform-dependent and have no unified implementation criteria. This limitation is reducing, however, through the rapid spread of the Voice over IP (VoIP) telephony service and its integration with mobile phones. The Session Initiation Protocol (SIP) is currently the standard signalling protocol of VoIP. Mobile payment is expected to be implemented and deployed in an SIP environment in order to keep pace with the evolution of the mobile phone network. The goal of this paper is firstly to propose a new mobile payment scheme based on SIP. The protocol of the proposed framework is thoroughly analysed. Secondly, we evaluate security issues and propose enhanced solutions to make this new framework applicable in practise

  • 3018.
    Zhang, Ge
    et al.
    Fraunhofer Institute FOKUS, Berlin, Germany.
    Ehlert, Sven
    Fraunhofer Institute FOKUS, Berlin, Germany.
    Magedanz, Thomas
    Fraunhofer Institute FOKUS, Berlin, Germany.
    Sisalem, Dorgham
    Tekelec, Berlin, Germany.
    Denial of Service Attack and Prevention on SIP VoIP Infrastructures Using DNS Flooding2007Ingår i: Proceedings of the 1st International Conference on Principles, Systems and Applications of IP Telecommunications (IPTCOMM 2007), New York: ACM Press, 2007, s. 57-66Konferensbidrag (Refereegranskat)
    Abstract [en]

    A simple yet effective Denial of Service (DoS) attack on SIP servers is to flood the server with requests addressed at irresolvable domain names.

  • 3019.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Fischer Hübner, Simone
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Peer-to-Peer VoIP Communications Using Anonymisation Overlay Networks2010Ingår i: Communications and Multimedia Security: Proceedings of the 11th IFIP TC 6/TC 11, CMS2010, international conference on Communications and Multimedia Security / [ed] De Decker, Bart; Schaumüller-Bichl, Ingrid, Berlin: Springer , 2010, s. 130-141Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nowadays, Voice over Internet Protocol (VoIP) which enables voice conversation remotely over packet switched networks gains much attentions for its low costs and flexible services. However, VoIP calling anonymity, particularly to withhold who called whom, is difficult to achieve since VoIP infrastructures are usually deployed in an open networking environment (e.g., the Internet). Our work studies an anonymisation overlay network (AON) based solution to prevent surveillance from external attackers, who are able to wiretap the communication channels as well as to manipulate voice packets in the channels. However, it has been demonstrated that the VoIP combined with traditional AONs are vulnerable to two attacks, namely watermark attack and complementary matching attack. Taking these two attacks into account, we investigate the defensive dropping method in VoIP: A VoIP user-agent sends packets to an AON in a constant rate, but packets during periods of silence are marked. Then, the AON drops some silence packets and forwards the remaining ones to their destinations. The result of our experiments shows that the dropping rate must be carefully selected to counteract both of the two attacks. Finally, we discuss further threats in terms of this solution

  • 3020.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Fischer Hübner, Simone
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Bezzi, Michele
    Duquenoy, Penny
    Hansen,, Marit
    Privacy and Identity Management for Life: 5th IFIP primelife international summer school revised selected papers2010Konferensbidrag (Refereegranskat)
  • 3021.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Fischer Hübner, Simone
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Pallares, Jordi Jaen
    Rebahi, Yacine
    SIP Proxies: New Reflectors? Attacks and Defenses2010Konferensbidrag (Refereegranskat)
    Abstract

    To mitigate identity theft in SIP networks, an inter-domain authentication mechanism based on certificates is proposed in RFC 4474 [10]. Unfortunately, the design of the certificate distribution in this mechanism yields some vulnerabilities. In this paper, we investigate an attack which exploits SIP infrastructures as reflectors to bring down a web server. Our experiments demonstrate that the attacks can be easily mounted. Finally, we discuss some potential methods to prevent this vulnerability

  • 3022.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Fischer-Hübner, Simone
    Karlstads universitet, Institutionen för informationsteknologi.
    A survey on anonymous voice over IP communication: attacks and defenses2019Ingår i: Electronic Commerce Research, ISSN 1389-5753, E-ISSN 1572-9362, ISSN 1389-5753, Vol. 19, nr 3, s. 655-687Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Anonymous voice over IP (VoIP) communication is important for many users, in particular, journalists, human rights workers and themilitary. Recent research work has shown an increasing interest in methods of anonymous VoIP communication. This survey starts by introducing and identifying the major concepts and challenges in this field. Then we review anonymity attacks on VoIP and the existing work done to design defending strategies. We also propose a taxonomy of attacks and defenses. Finally, we discuss possible future work.

  • 3023.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Fischer-Hübner, Simone
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Counteract DNS Attacks on SIP Proxies Using Bloom Filters2013Ingår i: 2013 International Conference on Availability, Reliability and Security, IEEE, 2013, s. 678-684Konferensbidrag (Refereegranskat)
    Abstract [en]

    SIP proxies play an important part in VoIP services. A Denial of Service (DoS) attack on them may cause the failure of the whole network. We investigate such a DoS attack by exploiting DNS queries. A SIP proxy needs to resolve domain names for processing a message. However, a DNS resolution may take a while. To avoid being blocked, a proxy suspends the processing task of the current message during its name resolution, so that it can continue to deal with other messages. Later when the answer is received, the suspended task will be resumed. It is an asynchronous implementation of DNS queries. Unfortunately, this implementation consumes memory storage and also brings troubles like a race condition. An attacker can collect a list of domain names which take seconds to resolve. Then, the attacker sends to a victim SIP proxy messages which contain these domain names. As a result, the victim proxy has to suspend a number of messages in a short while. Our experiments show that a SIP proxy can be easily crashed by such an attack and thus be not available anymore. To solve the problem, we analyzed the reasons that make a DNS query time-consuming, and then proposed a prevention scheme using bloom filters to blacklist suspicious DNS authoritative servers. Results of our experiments show it efficiently mitigates the attack with a reasonable false positive rate.

  • 3024.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Fischer-Hübner, Simone
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Ehlert, Sven
    Blocking attacks on SIP VoIP proxies caused by external processing2010Ingår i: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 45, nr 1, s. 61-76Artikel i tidskrift (Refereegranskat)
  • 3025.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Fischer-Hübner, Simone
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Martucci, Leonardo A.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Ehlert, Sven
    Fraunhofer FOKUS, Berlin, Germany.
    Revealing the calling history on SIP VoIP systems by timing attacks2009Ingår i: Proceedings of the 4th International Conference on Availability, Reliability and Security (ARES 2009), IEEE Press, IEEE Computer Society, 2009, s. 135-142Konferensbidrag (Refereegranskat)
    Abstract [en]

    Many emergent security threats which did not exist in the traditional telephony network are introduced in SIP VoIP services. To provide high-level security assurance to SIP VoIP services, an inter-domain authentication mechanism is defined in RFC 4474. However, this mechanism introduces another vulnerability: a timing attack which can be used for effectively revealing the calling history of a group of VoIP users. The idea here is to exploit the certificate cache mechanisms supported by SIP VoIP infrastructures, in which the certificate from a caller's domain will be cached by the callee's proxy to accelerate subsequent requests. Therefore, SIP processing time varies depending whether the two domains had been into contact beforehand or not. The attacker can thus profile the calling history of a SIP domain by sending probing requests and observing the time required for processing. The result of our experiments demonstrates that this attack can be easily launched. We also discuss countermeasures to prevent such attacks

  • 3026.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Pallares, Jordi Jaen
    Rebahi, Yacine
    Fischer-Hübner, Simone
    Karlstads universitet, Institutionen för informationsteknologi.
    SIP Proxies: New Reflectors in the Internet2010Ingår i: Communications and Multimedia Security: 11th IFIP TC 6/TC 11 International Conference, CMS 2010, Linz, Austria, May 31 – June 2, 2010. Proceedings, Springer, 2010, s. 142-153Konferensbidrag (Refereegranskat)
    Abstract [en]

    To mitigate identity theft in SIP networks, an inter-domain authentication mechanism based on certificates is proposed in RFC 4474 [10]. Unfortunately, the design of the certificate distribution in this mechanism yields some vulnerabilities. In this paper, we investigate an attack which exploits SIP infrastructures as reflectors to bring down a web server. Our experiments demonstrate that the attacks can be easily mounted. Finally, we discuss some potential methods to prevent this vulnerability.

  • 3027.
    Zhang, Ge
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Rebahi, Yacine
    Tuan Minh, Nguyen
    Performance Analysis of Identity Management in the Session Initiation protocol (SIP)2009Ingår i: Communications of the ACS, ISSN 2090-102X, Vol. 2, nr 001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Session Initiation Protocol (SIP) is a standard for managing IP multimedia sessions in the Internet. Identity management in SIP is a crucial security field that deals with identifying users in SIP networks and controlling their access to the corresponding resources. RFC 4474 describes a mechanism, based on certificates, for dealing with the SIP users identities. This RFC recommends the use of the RSA algorithm as it is currently the most popular public key cryptography system. The proliferation of small and simple devices as well as the need to increase the capacity of the SIP servers to handle the increasing VoIP traffic will make continued reliance on RSA more challenging over time. In this paper, we describe our implementation of the current RFC 4474, our integration of elliptic curves cryptography into this RFC and show that the corresponding performance is much more significant than the one where RSA is used. This paper can be considered as a first step in standardizing the use of elliptic curves in the identity management for SIP

  • 3028. Zhang, Xiaojing
    et al.
    Lindberg, Therese
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för ingenjörsvetenskap och fysik (from 2013).
    Xiong, N.
    Vyatkin, Valeriy
    Mousavi, Atash
    Cooling Energy Consumption Investigation of Data Center IT Room with Vertical Placed Server2017Ingår i: Energy Procedia, ISSN 1876-6102, Vol. 105, s. 2047-2052Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As energy consumption by cooling data center IT equipment can be over 40 % of total energy consumption, efficient cooling for large data centers is essential for reducing operation costs. Modern data centers are complex systems involving IT facilities, power system, cooling and ventilation systems. In our previous work, literature study was made to investigate available data center energy consumption models; and energy consumption models for data center IT room with distributed air flow control were developed. In this paper, the models are further extended and developed to cover the combined distributed air flow control and vertical placed servers in raised floor ventilation system. Simulation of the three types of ventilation systems with Even load, Idle server and Uneven load scenarios showed that significant cooling energy consumed by a traditional ventilation system can be saved by applying the proposed new concept and method. (C) 2017 The Authors. Published by Elsevier Ltd.

    Ladda ner fulltext (pdf)
    Zhang2017
  • 3029.
    Zhu, Yuxiang
    et al.
    Shandong University of Science and Technology, China.
    Peng, Yanjun
    Shandong University of Science and Technology, China.
    Asl, Arsineh Boodaghian
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Handelshögskolan (from 2013).
    Dual Adaptive Adjustment for Customized Garment Pattern2019Ingår i: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, s. 1-12, artikel-id 8069373Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a dual adaptive garment slice adjustment technique for automatic resizing of apparel products with variant body shapes, and this technique can quickly generate clothed characters. Our first contribution is to propose a novel fit evaluation method. When a 2D garment pattern and a 3D draped garment have the same triangle topology connection, we calculate the shape variable of each triangle and output heat map simultaneously. For sewing a pattern to a newly targeted human body, we propose a fully automatic adjustment method that conforms to the body structure and is composed of two stages. In the coarse auto adjustment (CAA) stage, we propose a method of controlling the size of a garment by the length of a bounding box in five parts of the human body. Then, the garment pattern is automatically adjusted using the measured dimension, by stretching or shrinking. In the fine auto adjustment (FAA) stage, boundary vertices control the shape in the adjustment process. For better matching with the body, the vertices of the garment pattern boundary are relocated with the calculated moving distance and moving direction. As demonstrated in the results, our method enables fully automatic adjustment, preserving the original pattern style of garments between characters with vastly body shapes. Compared with the state-of-art 2D editing method, our proposed approach leads to time saving, and it achieves realistic garment effect compared to auto fitting methods.

  • 3030. Zibuschka, Jan
    et al.
    Fritsch, Lothar
    Norsk Regnesentral.
    A hybrid approach for highly available & secure storage of pseudo-SSO credentials2012Ingår i: Secure IT Systems: 17th Nordic Conference, NordSec 2012, Karlskrona, Sweden, October 31 – November 2, 2012. Proceedings, Springer, 2012, s. 169-183Konferensbidrag (Refereegranskat)
    Abstract [en]

    Abstract: We present a novel approach for password/credential storage in Pseudo-SSO scenarios based on a hybrid password hashing/password syncing approach that is directly applicable to the contemporary Web. The approach supports passwords without requiring modification of the server side and thus is immediately useful; however, it may still prove useful for storing more advanced credentials in future SSO and identity management scenarios, and offers a high level of security. Keywords. Single sign-on, authentication, syncing, hashing.

  • 3031.
    Zibuschka, Jan
    et al.
    Goethe University.
    Fritsch, Lothar
    Goethe University.
    Radmacher, Mike
    Goethe University.
    Scherner, Tobias
    Goethe University.
    Rannenberg, Kai
    Goethe University.
    Enabling privacy of real-life LBS: A platform for flexible mobile service provisioning2007Ingår i: New Approaches for Security, Privacy and Trust in Complex Environments, Springer, 2007, s. 325-336Konferensbidrag (Refereegranskat)
    Abstract [en]

    Privacy in computerized environments is perceived very differently depending on the respective point of view. Often "privacy enhancing technologies" - initiated by the user, as a measure of self-defense - are seen as conflicting with business goals such as cost-efficiency, revenue assurance, and options for further business development based on existing data. This paper presents the design and implementation of an architecture and prototype for privacy-friendly, interoperable location-based services (LBS), based on intermediation of location data via a location middleware component. The aim is to combine privacy-friendliness, efficiency, and market potential. Therefore the security interests of the stakeholders are analyzed and an architecture solution including an intermediary is introduced. Then the prototype implementation (at a mobile operator) is described and the usage of the prototype for a commercial service and product offer by the operator involved in the development is discussed.

  • 3032.
    Ziegenbein, Marius-Lukas
    Karlstads universitet, Fakulteten för humaniora och samhällsvetenskap (from 2013), Handelshögskolan (from 2013).
    Fighting the Biggest Lie on the Internet: Improving Readership of Terms of Service and Privacy Policies2022Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    When joining a new service, in order to access its features, users are often required to accept the terms of service and privacy policy. However, the readership of these documents is mostly non-existent, leaving an information asymmetry, the imbalance of knowledge between two parties. Due to this, users are sacrificing their online data privacy without being aware of the consequences. The purpose of this work is to investigate the readership of terms of service and privacy policies among users of social media services. We implemented a prototype called ‘ShareIt’, which resembles a photo-sharing platform to gain insight about readership, behavior and effectiveness of our adjusted presentations of terms of service and privacy policies in regard to readership and comprehension. We conducted a survey experiment using the prototype with 31 participants and concluded, that 80,6% of our participants did not spend more than ten seconds in our terms of serviceand privacy policy. The observed behavior suggests, that social media users are used to sharing information on the internet which in addition to their trust towards online services leads to the aforementioned low readership. We presented adjustments to the presentation of terms of service and privacy policies which showed a slight tendency of higher engagement in comparison to the current way of accessing these documents. This result however, due to the lack of readership examined for our participants, has to remain debatable and needs further investigation.

    Ladda ner fulltext (pdf)
    fulltext
  • 3033. Zola, Enria
    et al.
    Barcelo-Arroyo, Francisco
    Dely, Peter
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Expected Bit Rate for Terminals Moving According to the Random Waypoint Model in a WLAN Cell2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The IEEE 802.11 standard defines the different bit rates and modulation schemes to which a WLAN device may adapt according to the channel quality. User mobility may also have an impact on the available bit rate. This paper presents a study of the bit rate evolution along time for devices that move according to the Random Waypoint mobility pattern in WLAN cells. Simulation has been applied in order to obtain statistical results that permit to characterize the evolution of the bit rate behavior along time and to compute average results in the ideal case (without interference) and in the presence of interfering devices. Our results can be useful in the solution of optimization problems in which decision on where to connect must be taken based on some minimum guaranteed bit rate. They also can be useful in the design of inter and intra-cell handover methods and load balancing schemes.

  • 3034. Zola, Enrica
    et al.
    Barcelo, Francisco
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Multi-objective Optimization of WLAN Associations with Improved Handover Costs2014Ingår i: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 18, nr 11Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The deployment of a large number of access points in public areas presents a new paradigm in which a given station may be served by more than one access point at a time. Recently, a network model has been proposed to derive the optimal association strategy for the stations by solving a linear optimization problem. According to that model, a station cannot download data while performing a handover. In this letter, we demonstrate that, even in static conditions (i.e., no mobility and constant load in the cell), an association strategy can force a handover. We thus propose a multi-objective optimization function that maximizes the download rates and minimizes the number of handovers. As a handover implies an extra cost due to necessary signaling to be exchanged, we propose a new handover cost function that takes into account the extra bandwidth. Using the new strategy, the system throughput slightly decreases, and the number of handovers is reduced.

  • 3035. Zola, Enrica
    et al.
    Dely, Peter
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Barcelo-Arroyo, Francisco
    Robust Association for Multi-radio Devices under Coverage of Multiple Networks2013Konferensbidrag (Refereegranskat)
  • 3036. Zola, Enrica
    et al.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Energy Efficient Control of Virtual Machine Consolidation under Uncertain Input Parameters for the Cloud2015Ingår i: Proceedings of the Workshop on Engineering and Control for Reliable Cloud Services, Ghent, Belgium, September 2015, 2015Konferensbidrag (Refereegranskat)
  • 3037.
    Zola, Enrica
    et al.
    UPC, Dept Network Engn, Barcelona, Spain.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Energy Efficient Virtual Machine Consolidation under Uncertain Input Parameters for Green Data Centers2015Ingår i: 2015 IEEE 7th International Conference on Cloud Computing Technology and Science (CloudCom), IEEE, 2015, s. 436-439Konferensbidrag (Refereegranskat)
    Abstract [en]

    Reducing the energy consumption of data centers and the Cloud is very important in order to lower CO2 footprint and operational cost (OPEX) of a Cloud operator. To this extent, it becomes crucial to minimise the energy consumption by consolidating the number of powered-on physical servers that host the given virtual machines (VMs). In this work, we propose a novel approach to the energy efficient VM consolidation problem by applying Robust Optimisation Theory. We develop a mathematical model as a robust Mixed Integer Linear Program under the assumption that the input to the problem (e.g. resource demands of the VMs) is not known precisely, but varies within given bounds. A numerical evaluation shows that our model allows the Cloud Operator to tradeoff between the power consumption and the protection from more severe and unlikely deviations of the uncertain input.

  • 3038.
    Zola, Enrica
    et al.
    Universitat Politècnica de Catalunya (UPC), Barcelona.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Optimising for Energy or Robustness? Trade-off for VM Consolidation under Uncertainty2016Ingår i: Optimization Letters, ISSN 1862-4472, E-ISSN 1862-4480Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reducing the energy consumption of virtualized datacenters and the Cloud is very important in order to lower CO2 footprint and operational cost of a Cloud operator. However, there is a trade-off between energy consumption and perceived application performance. In order to save energy, Cloud operators want to consolidate as many Virtual Machines (VM) on the fewest possible physical servers, possibly involving overbooking of resources. However, that may involve SLA violations when many VMs run on peak load. Such consolidation is typically done using VM migration techniques, which stress the network. As a consequence, it is important to find the right balance between the energy consumption and the number of migrations to perform. Unfortunately, the resources that a VM requires are not precisely known in advance, which makes it very difficult to optimise the VM migration schedule. In this paper, we therefore propose a novel approach based on the theory of robust optimisation. We model the VM consolidation problem as a robust Mixed Integer Linear Program and allow to specify bounds for e.g. resource requirements of the VMs. We show that, by using our model, Cloud operators can effectively trade-off uncertainty of resource requirements with total energy consumption. Also, our model allows us to quantify the price of the robustness in terms of energy saving against resource requirement violations.

  • 3039. Zola, Enrica
    et al.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Kim, Wooseong
    Joint User Association and Energy Aware Routing for Green Small Cell mmWave Backhaul Networks2017Ingår i: 2017 IEEE Wireless Communications and Networking Conference (WCNC), IEEE, 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    A dense deployment of small cells is one of the key characteristics envisioned for future 5G mobile networks in order to provide the required capacity increase. To cut cabling costs, small cells are foreseen to form multihop topologies using high capacity backhaul wireless links in the mmWave bands. Such small cells are deployed within the coverage area of a macro cell (eNB) to provide localized capacity where needed according to the well known Heterogeneous Network concept (HetNet). However, green networking will be very important because powering on unnecessarily a massive amount of small cells may lead to increased OPEX and CO2 emission. In this paper, we propose an optimization model that minimizes the total power consumption of 5G HetNets deployments while providing the required capacity and coverage. Our model jointly optimizes the user association, routing in the multihop backhaul and decides to power on or off the small cells to serve the user demands. Our numerical evaluation show significant power savings over a large range of traffic demand distributions while keeping the blocking probability low.

  • 3040. Zola, Erica
    et al.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Minimizing the Impact of Handover in WLAN: A Study on Performance Optimization2015Ingår i: Proceedings of SWE-CTW 2015, May 27th – 29th, Karlstad, Sweden, 2015Konferensbidrag (Refereegranskat)
  • 3041. Zuccato, Albin
    A Decision Matrix Approach to Prioritize Holistic Security Requirements in E-Commerce2005Konferensbidrag (Refereegranskat)
  • 3042. Zuccato, Albin
    A Holistic Information Security Management Frameworkapplied for electronic and mobile commerce2002Konferensbidrag (Refereegranskat)
  • 3043. Zuccato, Albin
    A modified mean value approach to assess securityrisks2002Konferensbidrag (Refereegranskat)
  • 3044. Zuccato, Albin
    Holistic Information Security Management Framework for electronic commerce2005Doktorsavhandling, monografi (Övrigt vetenskapligt)
  • 3045. Zuccato, Albin
    Holistic security management framework applied in electronic commerce2007Ingår i: Computers & Security 26(3), s. 256-265Artikel i tidskrift (Refereegranskat)
  • 3046. Zuccato, Albin
    Holistic security requirement engineering for electronic commerce2004Ingår i: Holistic security requirement engineering for electronic commerceArtikel i tidskrift (Refereegranskat)
  • 3047. Zuccato, Albin
    Introducing privacy risks in a companies information system security risk analysis2004Konferensbidrag (Refereegranskat)
  • 3048. Zuccato, Albin
    Legislation and economical aspects of ElectronicMoney with special viewpoint on Europe1999Konferensbidrag (Refereegranskat)
  • 3049. Zuccato, Albin
    Privacy Risk Management in a Business Environment2003Ingår i: / [ed] John Sören Pettersson, 2003Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 3050. Zuccato, Albin
    Towards a systemic holistic security management2002Övrigt (Övrig (populärvetenskap, debatt, mm))
    Abstract [en]

    Information System Security and its management "is a parasite on the profit" Gerald Kovacich.



    This thesis presents research intended to both modify the understanding for, and to introduce information system security not only as a cost factor but also as a business enabler for eCommerce systems. To achieve this, system theoretic concepts will be applied to information security management, taking technology, sociology and business aspects into consideration. The first aspects dealt with are security conception and system specification. A set of requirements for electronic money systems has been developed. However, security management does not only consist of requirement specifications, but must also open for an economically and socially acceptable implementation. Therefore we have developed a holistic framework for security management. This framework describes the activities and workflows that lead to satisfactory security levels in eCommerce. To be able to develop an understandable framework we apply black boxing in order to hide details. The development progress results in investigations of some of the black boxes mentioned. To motivate the need of inclusion in the framework, two of these inquires will be presented, where the first one deals with the improvement of a risk assessment methodology for faster application in e-commerce, and the second one with the influence of the Internet on privacy.

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