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  • 251.
    Bennani, Zakaria
    KTH, Tidigare Institutioner, Teleinformatik.
    Quality of Service Support for Wireless LANs2000Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    As the research and development of mobile computing is becoming increasingly interesting and important to corporations and private users, great efforts are being made to ensure that the wireless network technology is being developed to match the performance level showed by wired network technologies. Introducing wireless mobile computing into already existing and operational situations, that have up to date been taken care of with wired technology, should not mean a degradation of the existing performance level. In other words, there should not be any decrease in the quality of service experienced by the end users due to the mobility or wireless factor.

    When developing quality of service support mechanisms that use characteristics specific to the Internet Protocol, considerations have to be made to make certain that the solutions and implementations developed will be deployable with the next generation Internet Protocol, IPv6. Since the ever decreasing address space in IPv4 is becoming more and more of a problem, at some point migration to IPv6 has to be made. Therefore, this thesis will base its developments on the use of IPv6.

    The thesis concerns the problem of providing statistical QoS guarantees for multimedia applications running over a wireless LAN such as WaveLAN. Using the DiffServ model and support of IPv6, we develop mechanisms for managing QoS and mobility. With the use of pre-connection schemes and a domain routing approach, Mobile Node mobility and Handoffs are handled in such a way to diminish latencies that occur when in-LAN and cross-LAN handoffs are made. To handle QoS guarantees, a bandwidth broker placed in the Access Points manages bandwidth allocations for different cells and configures the traffic parameters of each mobile so that the usage of the wireless MAC layer is controlled. The border router is connected via ATM to core routers in several places in France. Experimentation on the platform involves a DIS application (Distributed Interactive Simulation) running at different sites.

    The development work is done on FreeBSD systems in C.

  • 252.
    Bennehag, David
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Wulcan, Alexander
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Claesson, ommy
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för automation och datateknik.
    Förstudie till ett stadstäckande och öppet WiFi i Trollhättan2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Förstudien behandlar den tekniska delen av ett teoretiskt stadstäckande öppet WiFi i Trollhättan, Sverige. Trollhättans kommun beställde en förstudie från Högskolan Väst som skulle agera beslutsunderlag till hur de skulle ta ärendet vidare. Studien är begränsad till den tekniska biten, där bland annat val av utrustning, trådlösa tekniker och riskanalys av nätverket ingår. Arbetet varit väldigt teoretiskt inriktat med en metod som till största del består utav att samla information och kunskaper från vetenskapliga rapporter, teknikorienterade hemsidor och andra relaterade arbeten.De trådlösa standarder som jämfördes teoretiskt i förstudien var 802.11g och 802.11n. 802.11n valdes som den standarden som bäst passade just detta nätverk, främst för dess positiva egenskaper när det gäller täckning, hastighet och bakåtkompatibilitet. 802.11n seräven ut att garantera en säker framtid när det gäller implementering i mobila enheter. Föreslaget på utrustning består av två olika accesspunkter, antingen 2602e eller 3602e beroende på den slutgiltiga budgeten. Dessa produkter är från Cisco och klarade olikastresstester med bra resultat samtidigt som de stödde den föreslagna standarden 802.11n. WLAN controllern (Ciscos 5500-serie) som valdes ut stödjer det krav på antal accesspunkter som bestämts, samtidigt som den lämpar sig bra för eventuella framtidakrav. Routern till detta nätverk är en Cisco 891-router. Anledningen till att denna router valdes var för att den har 4 portar som kan ge ström över Ethernet till accesspunkterna. Säkerhetsanalysen gjordes med hjälp utav CORAS-metoden där det diskuteras vilka riskernätverket kan ställas inför och vad dessa risker kan få för konsekvenser. Försök till att hitta lösningar som var direkt applicerbara på det stadstäckande öppna nätverket gjordes även.Förstudien avslutas med en kostnadsberäkning av nätverket, baserad på andras tidigare arbeten och deras kostnader, speciellt från Jönköping, Helsingborg och Mountain View.

  • 253.
    Bentahar, Younes
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    DNS prestanda2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Use of computers and computer networks is nowadays a part of everyday life. You do not use them only at home when you sit at you computer, but you can use them all the time everywhere. This can involve everything from surf to any website when you are at home, to checking your email on your mobile when you are on your way to work. Most people do not think about how it really works when they try to access a web page by typing the address into their browser, but something that most people probably notice is how long it can sometimes take to access a web page.

    All items which are directly connected to the IP network have a unique IP address that is used to make it possible to communicate. The IP address is either a period separated sequence of digits representing 32 bits or a colon separated sequence of digits representing 128 bits, depending on whether the address is an IPv4 or IPv6 address. Such numeric sequences are often difficult for us humans to remember therefore, the domain name system (DNS) was constructed. DNS makes it possible for us to write addresses in a textual format to access an item stored in a device connected to the network. DNS can be seen as a directory for the network and can be compared to a telephone directory, where if you know the name of a person can find his or her phone number.

    This thesis will describe how the various address translations are done by using DNS. It will also examine how much impact DNS has on the experienced delay from the time you type a web page address in the address bar of your browser to the actual time you reach the website. A survey of DNS performance will be presented to investigate how much delay can be reduced by using one of Sweden's two most well-known public DNS servers (Google Public DNS and OpenDNS) instead of the normal default DNS server provided by one's Internet service provider (ISP).

    The survey will also show how the DNS lookup waiting time changes at different times of day and different days of the week. The purpose of this work is to provide a basic explanation of what DNS is and increase the understanding of how an everyday user in a simple way can make their network usage more effective by getting their DNS lookups to occur faster.

    The conclusion from this thesis is that the alternative DNS server, Google Public DNS has the fastest DNS lookup time for this particular computer which the measurement was carried on. But this tells us nothing about whether the case for any other network users because the observed DNS performance has a large extent dependent on the ISP you are connected to, and what place you are at.

  • 254.
    Bentes, João
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR Centrum för tillämpade intelligenta system (IS-lab).
    Khandelwal, Siddhartha
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR Centrum för tillämpade intelligenta system (IS-lab).
    Carlsson, Hampus
    Högskolan i Halmstad, Akademin för informationsteknologi.
    Kärrman, Marcus
    Högskolan i Halmstad, Akademin för informationsteknologi.
    Svensson, Tim
    Högskolan i Halmstad, Akademin för informationsteknologi.
    Wickström, Nicholas
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR Centrum för tillämpade intelligenta system (IS-lab).
    Novel System Architecture for Online Gait Analysis2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Although wearable devices can be used to perform continuous gait analysis in daily life, existing platforms only support short-term analysis in quasi-controlled environments. This paper proposes a novel system architecture that is designed for long-term, online gait analysis in free-living environments. Various aspects related to the feasibility and scalability of the proposed system are presented.

  • 255. Bentley, Frank
    et al.
    Tollmar, Konrad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Designing From Data: A Case Study From the Health Mashups Service2013Inngår i: Workshop on Informing Future Design via Large-Scale Research Methods and Big Data, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Instrumentation of mobile service interactions now allows for the ability to understand use in new ways and to base the design of system iterations as well as future services on data obtained from use “in the wild”over extended periods of time. This position paper will detail a few specific instances in the Health Mashupsproject where we were able to use usage data to improve the design and to create design implications to increase engagement in new services.

  • 256. Bentley, Frank
    et al.
    Tollmar, Konrad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Mobile Service Laboratory (MS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Stephenson, Peter
    Levy, Laura
    Jones, Brian
    Robertson, Scott
    Price, Ed
    Catrambone, Richard
    Wilson, Jeff
    Health Mashups: Presenting Statistical Patterns between Wellbeing Data and Context in Natural Language to Promote Behavior Change2013Inngår i: ACM Transactions on Computer-Human Interaction, ISSN 1073-0516, Vol. 20, nr 5, 30- s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    People now have access to many sources of data about their health and wellbeing. Yet, most people cannot wade through all of this data to answer basic questions about their long-term wellbeing: Do I gain weight when I have busy days? Do I walk more when I work in the city? Do I sleep better on nights after I work out? We built the Health Mashups system to identify connections that are significant over time between weight, sleep, step count, calendar data, location, weather, pain, food intake, and mood. These significant observations are displayed in a mobile application using natural language, for example, "You are happier on days when you sleep more." We performed a pilot study, made improvements to the system, and then conducted a 90-day trial with 60 diverse participants, learning that interactions between wellbeing and context are highly individual and that our system supported an increased self-understanding that lead to focused behavior changes.

  • 257.
    Berbineau, Marion
    et al.
    IFSTTAR, Villeneuve d’Ascq, France.
    Jonsson, MagnusHögskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).Bonnin, Jean-MarieTelecom Bretagne, Cesson Sévigné, France.Cherkaoui, SoumayaUniversité de Sherbrooke, Canada.Aguado, MarinaUniversity of the Basque Country, Bilbao, Spain.Rico Garcia, CristinaDLR, German Aerospace Center, Oberpfaffenhofen-Wessling, Germany.Ghannoum, HassanSNCF, Paris, France.Mehmood, RashidUniversity of Huddersfield, UK.Vinel, AlexeyTampere University of Technology, Finland.
    Communication Technologies for Vehicles: 5th International Workshop, Nets4Cars/Nets4Trains 2013, Villeneuve d' Ascq, France, May 14-15, 2013, Proceedings2013Konferanseproceedings (Fagfellevurdert)
  • 258. Berg, Jacob
    et al.
    Landin, Niclas
    Kommunikationskort2017Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Raytelligence har utvecklat en radar som kan registrera rörelse och hjärtfrekvens hos människor. Datan från radarn skickas över Universal Serial Bus (USB) till en extern dator. För att produkten ska bli mer användarvänlig krävs en bättre kommunikationslösning. Projektet går ut på att implementera en trådlös kommunikation i form av bluetooth och Wireless Local Area Network (WLAN) som kan skicka datan från radarn trådlöst till en extern dator eller mobil enhet. I rapporten beskrivs de olika metoderna som använts för att åstadkomma den trådlösa kommunikationen. Det beskrivs passande gränssnitt, val av passande kommunikationsmodul, implementering och kalibrering av antenn, val av komponenter och olika sätt att motverka Elektromagnetisk Interferens (EMI) för att få bra förutsättningar för en Elektromagnetisk kompatibilitet (EMC)-certifiering. Resultatet av projektet är en produkt som bygger på kommunikationsmodulen RS9113 och Raytelligence radarkort.

  • 259.
    Bergblomma, Marcus
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Martin
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Gerdtman, Christer
    Motion Control AB, Västerås, Sweden .
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    A wireless low latency control system for harsh environments2012Inngår i: IFAC Proceedings Volumes (IFAC-PapersOnline): Vol. 11, PART 1, 2012, 17-22 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The use of wireless communication technologies in the industry offer severaladvantages. One advantage is the ability to deploy sensors where they previously could noteasily be deployed, for instance on parts that rotate. To use wireless communication in industrialcontrol loops, demands on reliability and latency requirements has to be met. This in anenvironment that may be harsh for radio communication. This work presents a reliable, lowlatency wireless communication system. The system is used in a wireless thyristor control loopin a hydro power plant generator. The wireless communication is based on Bluetooth radiomodules. The work shows a latency analysis together with empirical hardware based latencyand packet error rate measurements. The background noise of a hydro power plant station isalso investigated. The average latency between the Bluetooth modules for the proposed systemis 5.09 ms. The packet error rate is 0.00288 for the wireless low latency control system deployedin a hydro power plant.

  • 260. Berger, Andre
    et al.
    Gross, James
    RWTH Aachen University, Germany.
    Harks, Tobias
    The k–Constrained Bipartite Matching Problem: Approximation Algorithms and Applications to Wireless Networks2010Inngår i: Proceedings IEEE INFOCOM, 2010, IEEE conference proceedings, 2010, 1-9 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In communication networks, resource assignment problems appear in several different settings. These problems are often modeled by a maximum weight matching problem in bipartite graphs and efficient matching algorithms are well known. In several applications, the corresponding matching problem has to be solved many times in a row as the underlying system operates in a time-slotted fashion and the edge weights change over time. However, changing the assignments can come with a certain cost for reconfiguration that depends on the number of changed edges between subsequent assignments. In order to control the cost of reconfiguration, we propose the k-constrained bipartite matching problem for bipartite graphs, which seeks an optimal matching that realizes at most k changes from a previous matching. We provide fast approximation algorithms with provable guarantees for this problem. Furthermore, to cope with the sequential nature of assignment problems, we introduce an online variant of the k-constrained matching problem and derive online algorithms that are based on our approximation algorithms for the k-constrained bipartite matching problem. Finally, we establish the applicability of our model and our algorithms in the context of OFDMA wireless networks finding a significant performance improvement for the proposed algorithms.

  • 261.
    Berggren, Anders
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Borg, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    A Comparative Study ofTwo Multicast Routing Algorithms2002Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This Master Thesis examines several aspects of two different multicast forwarding algorithms. The scaling properties of the currently used algorithms were examined under different criteria, such as delay, traffic concentration, and size of the routing tables.

    Many new Internet applications, such as videoconferencing, resource discovery, Internet radio and online games, depend on a network support for efficient point-to-multipoint communication. Sending identical data to a group of receivers using a series of unicast transmissions obviously has massive scaling problems. Multicasting provides an efficient and elegant solution that significantly reduces the total bandwidth demand as well as the load on both senders and intermediate routers.

    In this report we study two multicast routing algorithms, source based trees (SBT) and core based trees (CBT). SBT builds one delivery tree per source and group by flooding the initial packet through the entire network, and then removing the links that do not lead to group members (“pruning”). To be able to discover new members, flooding must occur periodically. CBT on the other hand, builds one delivery tree per group, shared by all sources. There is one core router per group and members must explicitly join the delivery tree by notifying the core. Off-tree sources must tunnel their traffic to the core for distribution along the tree.

    SBT has two main drawbacks. Firstly, the maintenance of the delivery tree requires periodic flooding of the network. Furthermore, SBT routers must keep state that grows as the product of the number of sources and the number of groups. CBT solves both of these scaling problems, but the shared tree will often lead to sub-optimal paths and increased delay. The traffic may also be concentrated on fewer links than in SBT.

    We compared the characteristics of the SBT and CBT algorithms in different network topologies using a simulation program. Since existing network simulation tools were found to be poor when it came to multicasting, we decided to develop a new network generator and simulator tool with multicasting aspects in focus. We also developed a tool to visualize the networks generated by the simulator and monitor the traffic. The report presents many simulation results that illustrate the significance of different trade-offs between SBT and CBT. Performance characteristics such as delay, join latency, tree size, total traffic and traffic concentration are analysed and examined.

    The conclusion is that each protocol can be preferable in certain scenarios, depending on how important the different parameters are. CBT always performs better than SBT for single source applications if the core can be placed at the sender’s local router. However, this core placement is not necessarily optimal for CBT. The situation is more complex in groups with several sources. There is a trade-off between the scaling problems of SBT and the increased delay and traffic concentration of CBT.

  • 262.
    Berggren, Fredrik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikation: Infrastruktur och tjänster (Stängd 20120101), Kommunikationssystem, CoS (stängd 2012-01-01).
    Capacity analysis for noncooperative interference environments2005Inngår i: VTC 2005-Spring: 2005 IEEE 61st Vehicular Technology Conference, Proceedings, IEEE , 2005, nr 3, 1479-1483 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To enhance the wireless bandwidth utilization, new forms of innovative spectrum policies, dynamically sharing channels over time and space, have been discussed. Dynamic spectrum access lets systems share the spectrum, to achieve better band-width utilization and trunking gains. In this work, we consider a case where such access is performed in an uncoordinated fashion. The paradigm shift to open frequency bands implies a need to investigate and verify resulting capacity gains. Herein, we give a general method for evaluating system capacity subject to outage probability constraints over fading channels, in an unlicensed band environment with uncoordinated systems. The channel fading effects include both attenuation, shadowing and multipath propagation and we end up with expressions, which are solved by numerical integration. The spectrum sharing is here performed by means of autonomous dynamic channel allocation (DCA), and we compare two DCA methods, maximum SIR DCA and random DCA.

  • 263.
    Berggren, Magnus
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Simon, Daniel
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Nilsson, D
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Dyreklev, P
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Norberg, P
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Nordlinder, S
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Ersman, PA
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Gustafsson, G
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Wikner, Jacob
    Linköpings universitet, Institutionen för systemteknik, Elektroniska Kretsar och System. Linköpings universitet, Tekniska fakulteten.
    Hederén, J
    DU Radio, Ericsson AB, SE-583 30, Linköping, Sweden..
    Hentzell, H
    Swedish ICT Research, Box 1151, SE-164 26, Kista, Sweden..
    Browsing the Real World using Organic Electronics, Si-Chips, and a Human Touch.2016Inngår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, nr 10, 1911-1916 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organic electronics have been developed according to an orthodox doctrine advocating "all-printed, "all-organic and "ultra-low-cost primarily targeting various e-paper applications. In order to harvest from the great opportunities afforded with organic electronics potentially operating as communication and sensor outposts within existing and future complex communication infrastructures, high-quality computing and communication protocols must be integrated with the organic electronics. Here, we debate and scrutinize the twinning of the signal-processing capability of traditional integrated silicon chips with organic electronics and sensors, and to use our body as a natural local network with our bare hand as the browser of the physical world. The resulting platform provides a body network, i.e., a personalized web, composed of e-label sensors, bioelectronics, and mobile devices that together make it possible to monitor and record both our ambience and health-status parameters, supported by the ubiquitous mobile network and the resources of the "cloud".

  • 264.
    Bergholm, Johan
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Gallardo, Sascha
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Svensson, Jonny
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Positionering och Spårning av mobila enheter, ur ett IT–forensiskt perspektiv2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    I dagens Sverige så har de mobila enheterna en självklar plats i våra fickor, likväl som i vårt samhälle och i dess brottslighet, vilket gör att det sedan några år är att anse självklart att de även har en central roll i IT–forensiska utredningar inom våra polismyndigheter. Men vid sidan av konkreta bevis för begångna brott lagrar enheterna dessutom ofta data som kan användas för att spåra enheten, och därmed också dess brukare, över tid, vilket givetvis är av intresse av polismyndigheter men skulle även kunna vara av stort intresse för exempelvis försäkringsbolag och andra delar av den 'civila sektorn' som driver utredningar men som saknar polisens befogenheter. För att ge ett så brett användningsområde som möjligt fokuserar därför rapporten inte bara på datat som är tillgängligt från den faktiska enheten och hur de kan användas för spårning och positionering, utan försöker även på praktiskt väg undersöka i vilken grad dessa metoder kan utföras med allmänt tillgänglig mjuk- och hårdvara.

  • 265.
    Berglund, Emil
    et al.
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media.
    Facklam, Alexander
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Institutionen för informatik och media.
    Framgång eller förfall?: Utvecklingen, riskerna och potentialen av BYOD2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Uppsatsen undersöker fenomenet Bring Your Own Device (BYOD), dess för- och nackdelar samt hur riskerna BYOD medför kan hanteras. För att uppnå detta har en litteraturstudie genomförts. Denna kompletteras av en enkätstudie på Stockholms Läns Landsting och tre intervjuer på Uppsala Kommun med målet att se hur dessa organisationer hanterar BYOD. Arbetet ger en djup insikt i BYOD olika aspekter och visar även på hur de risker som uppkommer kan hanteras.

  • 266.
    Berglund, Joel
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Extended LTE Coverage For Indoor Machine Type Communication2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The interest of Machine Type Communication (MTC) is increasing and is expected to play an important role in the future network society. In the process of increasing the number of connected devices, the coverage plays an important role. This thesis work aims to study the possibility of supporting coverage limited MTC-devices within LTE by extending the LTE coverage.

    It shows that coverage increase by means of repetition is a good candidate, which allows for a significant increase without hardware upgrades at a low cost in terms of radio resources. For inter-site distances up to 2500 m, the proposed repetition scheme with an increase of 20 dB allows for almost complete coverage where today’s LTE have significant lack of coverage. It also shows that even though the increased coverage implies higher resource usage, the limitation is not in the number of users supported, but rather the coverage at longer inter-site distances.

  • 267.
    Berglund, Martin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Lotfi, Sara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization, and control design2013Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 4, 045020- s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a lumped thermal model of a dual-axis laser micromirror device for beam steering in a free-space optical (FSO) communication system, designed for fractionated spacecraft. An FSO communication system provides several advantages, such as larger bandwidth, smaller size and weight of the communication payload and less power consumption. A dual-axis mirror device is designed and realized using microelectromechanical systems technology. The fabrication is based on a double-sided, bulk micromachining process, where the mirror actuates thermally by joints consisting of v-grooves filled with the SU-8 polymer. The size of the device, consisting of a mirror, which is deflectable versus its frame in one direction, and through deflection of the frame in the other, is 15.4 × 10.4 × 0.3 mm3. In order to further characterize and understand the micromirror device, a Simulink state-space model of the actuator is set up using thermal and mechanical properties from a realized actuator. A deviation of less than 2% between the modelled and measured devices was obtained in an actuating temperature range of 20–200 °C. The model of the physical device was examined by evaluating its performance in vacuum, and by changing physical parameters, such as thickness and material composition. By this, design parameters were evaluated for performance gain and usability. For example, the crosstalk between the two actuators deflecting the mirror along its two axes in atmospheric pressure is projected to go down from 97% to 6% when changing the frame material from silicon to silicon dioxide. A feedback control system was also designed around the model in order to examine the possibility to make a robust control system for the physical device. In conclusion, the model of the actuator presented in this paper can be used for further understanding and development of the actuator system.

  • 268.
    Bergman, Svante
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Lattice based linear precoding for MIMO block codes2007Inngår i: 2007 IEEE International Conference on Acoustics, Speech, and Signal Processing, IEEE , 2007, 329-332 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Herein, the design of linear dispersion codes for block based multiple-input multiple-output communication systems is investigated. The receiver as well as the transmitter are assumed to have perfect knowledge of the channel, and the receiver is assumed to employ maximum likelihood detection. We propose to use linear precoding and lattice invariant operations to transform the channel matrix into a lattice with large coding gain. With appropriate approximations, it is shown that this corresponds to selecting lattices with good sphere packing properties. Lattice invariant transformations are then used to minimize the power consumption. An algorithm for this power minimization is presented along with a lower bound on the optimization. Numerical results indicate that there is a potential gain of several dB by using the method compared to channel inversion with adaptive bit loading.

  • 269.
    Bergman, Svante
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Lattice-based linear precoding for MIMO channels with transmitter CSI2008Inngår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 56, nr 7, 2902-2914 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein, the design of linear dispersion codes for multiple-input multiple-output communication systems is investigated. The receiver as well as the transmitter are assumed to have perfect knowledge of the channel, and the receiver is assumed to employ maximum likelihood detection. We propose to use linear precoding and lattice invariant operations to transform the channel matrix into a lattice generator matrix with large minimum distance separation. With appropriate approximations, it is shown that this corresponds to selecting lattices with good sphere-packing properties. Lattice invariant transformations are then used to minimize the power consumption. An algorithm for this power minimization is presented along with a lower bound on the optimization. Numerical results indicate significant gains by using the proposed method compared to channel diagonalization with adaptive bit loading.

  • 270.
    Bergman, Svante
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Palomar, Daniel P.
    Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Joint Bit Allocation and Precoding for MIMO Systems With Decision Feedback Detection2009Inngår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 57, nr 11, 4509-4521 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper considers the joint design of bit loading, precoding and receive filters for a multiple-input multiple-output (MIMO) digital communication system employing decision feedback (DF) detection at the receiver. Both the transmitter as well as the receiver are assumed to know the channel matrix perfectly. It is well known that, for linear MIMO transceivers, a diagonal transmission (i.e., orthogonalization of the channel matrix) is optimal for some criteria. Surprisingly, it was shown five years ago that for the family of Schur-convex functions an additional rotation of the symbols is necessary. However, if the bit loading is optimized jointly with the linear transceiver, then this rotation is unnecessary. Similarly, for DF MIMO optimized transceivers a rotation of the symbols is sometimes needed. The main result of this paper shows that for a DF MIMO transceiver where the bit loading is jointly optimized with the transceiver filters, the rotation of the symbols becomes unnecessary, and because of this, also the DF part of the receiver is not required. The proof is based on a relaxation of the available bit rates on the individual substreams to the set of positive real numbers. In practice, the signal constellations are discrete and the optimal relaxed bit loading has to be rounded. It is shown that the loss due to rounding is small, and an upper bound on the maximum loss is derived. Numerical results are presented that confirm the theoretical results and demonstrate that orthogonal transmission and the truly optimal DF design perform almost equally well.

  • 271.
    Bergqvist, Joakim
    KTH, Tidigare Institutioner, Teleinformatik.
    Dynamic modeling of real-time data sources1996Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis reports on the development and implementation of a method for dynamically generating a state model from the prerecorded trace of a cell-arrival process and the user of this state machine to drive a simulator to evaluate the effects of multiplexing multiple copies of traffic similar to the original trace.

  • 272.
    Bergsaker, Agnethe
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för informatik (IK). Centrum för Informationslogistik.
    Standardsystem och användbarhet: Hur ska man som utvecklare säkra att användbarhet uppnås i små SharePoint-projekt?2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    IT (Informationsteknologi) används i dag mycket för att distribuera och förmedla information internt och externt. Ett bra verktyg för informationshantering är verksamhetens intranät. Arbetet handlar om användbarhet i små SharePoint-projekt. Med användbarhet omfattas faktorerna användarvänlighet, anpassning och användaracceptans. Små SharePoint-projekt (på under 300 timmar) innebär att det finns mindre resurser för att tillämpa användbarhet.

    Syftet med detta arbete är att undersöka utvecklare inom SharePoint sina åsikter och förhållningssätt kring användbarhet, samt hur användbarhet bäst kan uppnås i små projekt med begränsade resurser. En kvantitativ metod har används för att genomföra fallstudie av tre utvecklare i ett konsultföretag. Intervjuerna har varit semistrukturerade.

    Resultatet av forskningen drar slutsatsen att användaracceptansen är avgörande för att ett intranät ska uppfattas som användbart för användarna. Användarvänligheten är i standard SharePoint redan relativt definierad och fastställd. Anpassning av ett system istället för att använda inbyggda standarder är ofta kostsamt och resurskrävande. Utvecklarna bör därmed fokusera på utbildning, användarmedverkan, kommunikation och andra faktorer som kan öka acceptansen hos slutanvändarna.

  • 273.
    Bergström, Andreas
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten. Ericsson Research.
    Hendeby, Gustaf
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Gunnarsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten. Ericsson Research.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    TOA Estimation Improvements in Multipath Environments by Measurement Error Models2017Inngår i: Proceedings of the 2017 IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC), Institute of Electrical and Electronics Engineers (IEEE), 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many positioning systems rely on accuratetime of arrival measurements. In this paper, we addressnot only the accuracy but also the relevance of Time ofArrival (TOA) measurement error modeling. We discusshow better knowledge of these errors can improve relativedistance estimation, and compare the impact of differentlydetailed measurement error information. These models arecompared in simulations based on models derived froman Ultra Wideband (UWB) measurement campaign. Theconclusion is that significant improvements can be madewithout providing detailed received signal information butwith a generic and relevant measurement error model.

  • 274.
    Berner, Jessica
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för datavetenskap, fysik och matematik, DFM.
    Wildt-Persson, Andrea
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för datavetenskap, fysik och matematik, DFM.
    Sociala Intranät: Dess användning, möjligheter och risker2011Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Organizations over the world increasingly start to realize the possibilities of the use of a social intranet, also known as Enterprise 2.0. The social intranets can be used to collaborate and communicate with colleagues in the workplace. Both Cook (2008) and Coope (Barnett, 2011) say that Enterprise 2.0 is about to fundamentally change the way organizations communicate. But do companies know how these tools can be used?

    The study emanates from three questions:

    • How can social intranets be used in business?
    • How can internal communication and collaboration get easier through the use of a social intranet?
    • What are the possible risks with the use of social intranets?

    In this study we have in a qualitative manner been interviewing two companies that currently use social intranets in their daily activities – Securitas and Skåneme-jerier. The interviews where performed via telephone with two people familiar with the respective social intranets. We have also sent out a questionnaire via e-mail to a user group of each company's intranet, to gain knowledge of users' opi-nions.

    The interviews show that both companies agree that it is important for peers to communicate and exchange information and knowledge with each other. The so-cial intranets are used both for communication, collecting employees' knowledge, and to ease the employees information need by gathering all information at the same place. Respondents also pointed out the advantage of written information and knowledge. As it is written it is also searchable. It will also remain in the organiza-tion even though the creator might leave the company. The fact that all users can edit for example wikis and files on the intranet can be used to keep information up to date.

  • 275.
    Berthold, Stefan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Inter-temporal Privacy Metrics2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Informational privacy of individuals has significantly gained importance after information technology has become widely deployed. Data, once digitalised, can be copied, distributed, and long-term stored at negligible costs. This has dramatic consequences for individuals that leave traces in the form of personal data whenever they interact with information technology, for instance, computers and phones; or even when information technology is recording the personal data of aware or unaware individuals. The right of individuals for informational privacy, in particular to control the flow and use of their personal data, is easily undermined by those controlling the information technology.

    The objective of this thesis is to study the measurement of informational privacy with a particular focus on scenarios where an individual discloses personal data to a second party which uses this data for re-identifying the individual within a set of other individuals. We contribute with privacy metrics for several instances of this scenario in the publications included in this thesis, most notably one which adds a time dimension to the scenario for modelling the effects of the time passed between data disclosure and usage. The result is a new framework for inter-temporal privacy metrics.

  • 276.
    Berthold, Stefan
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Lundin, Reine
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap.
    Re-identification revisitedManuskript (preprint) (Annet vitenskapelig)
  • 277.
    Bertilsson, Erik
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    A Scalable Architecture for Massive MIMO Base Stations Using Distributed Processing2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Massive MIMO is an emerging technology for future wireless systems that has received much attention from both academia and industry recently. The most prominent feature of Massive MIMO is that the base station is equiped with a large number of antennas. It is therefore important to create scalable architectures to enable simple deployment in different configurations.

    In this thesis, a distributed architecture for performing the baseband processing in a massive OFDM MU-MIMO system is proposed and analyzed. The proposed architecture is based on connecting several identical nodes in a K-ary tree. It is shown that, depending on the chosen algorithms, all or most computations can be performed in a distrbuted manner. Also, the computational load of each node does not depend on the number of nodes in the tree (except for some timing issues) which implies simple scalability of the system.

    It is shown that it should be enough that each node contains one or two complex multipliers and a few complex adders running at a couple of hundres MHz to support specifications similar to LTE. Additionally the nodes must communicate with each other over links with data rates in the order of some Gbps.

    Finally, a VHDL implementation of the system is proposed. The implementation is parameterized such that a system can be generated from a given specification.

  • 278.
    Bertilsson, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    A Scalable Architecture for Massive MIMO Base Stations Using Distributed Processing2016Inngår i: 2016 50TH ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS AND COMPUTERS, Washington: IEEE COMPUTER SOC , 2016, 864-868 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Massive MIMO-systems have received considerable attention in recent years as an enabler in future wireless communication systems. As the idea is based on having a large number of antennas at the base station it is important to have both a scalable and distributed realization of such a system to ease deployment. Most work so far have focused on the theoretical aspects although a few demonstrators have been reported. In this work, we propose a base station architecture based on connecting the processing nodes in a K-ary tree, allowing simple scalability. Furthermore, it is shown that most of the processing can be performed locally in each node. Further analysis of the node processing shows that it should be enough that each node contains one or two complex multipliers and a few complex adders/subtracters operating at some hundred MHz. It is also shown that a communication link of some Gbps is required between the nodes, and, hence, it is fully feasible to have one or a few links between the nodes to cope with the communication requirements.

  • 279.
    Bhatia, Nupur
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Policy Management in Context-Aware Networks2007Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The Ambient Network (AN) Project is part of the European Commission’s 6th Framework Programme and aims to enable cooperation between heterogeneous networks, using current and future wireless technologies, minimising the effort of mobile users to gain access to the services that they are interested in - irrespective of their location or the network they are currently using. Because of the highly mobile nature of users and a demand for instant and dynamic access to services, these networks have to be composed ‘on the fly’ without any pre-configurations.

    The use of context information in AN can remove the need for pre-configuration of networks, hence making them autonomic. However, a concern exists that the free and uncontrolled dissemination of context information could breech the privacy of the participants. It is extremely important to address these privacy issues in order to control who has access to what context information. This control can be achieved through the use of well defined policies. This creates a requirement for a framework in the ContextWare architecture for protecting context information.

    This masters thesis project is part of an effort to create a policy based infrastructure for authorisation of access to network context information within the AN. The thesis investigates, models, and designs an architecture for a policy management system based on OASIS XACML, that creates an extension to the architecture for management of context information in the AN. In addition to a policy management architecture within an AN, a policy management architecture for composing ANs is also created. To facilitate the transfer of requests and policies, the thesis creates a Policy Management Protocol. The designed architecture was then implemented to create a proof of concept.

    The designed architecture and protocol were evaluated by running tests on the prototype. The measurements from the tests are analysed and presented in this thesis. The analysis of the experimental data indicates that a policy management system is both feasible and practical. The results show that the delay overhead caused by introducing policy management in a distributed context provisioning system, ranges from 1.7% in a system without load to 6% in a worst case scenario. The throughput of the policy management system is 15 requests per second under load.

  • 280.
    Bhatti, Ayesha
    Linköpings universitet, Institutionen för datavetenskap.
    Snippet Generation for Provenance Workflows2011Independent thesis Advanced level (degree of Master (Two Years)), 30 poäng / 45 hpOppgave
    Abstract [en]

    Scientists often need to know how data was derived in addition to what it is. The detailed tracking of data transformation or provenance allows result reproducibility, knowledge reuse and data analysis. Scientific workflows are increasingly being used to represent provenance as they are capable of recording complicated processes at various levels of detail. In context of knowledge reuse and sharing; search technology is of paramount importance specially considering the huge and ever increasing amount of scientific data. It is computationally hard to produce a single exact answer to the user's query due to sheer volume and complicated structure of provenance.  One solution to this difficult problem is to produce a list of candidate matches and let user select the most relevant result. Here search result presentation becomes very important as the user is required to make the final decision by looking at the workflows in the result list. Presentation of these candidate matches needs to be brief, precise, clear and revealing. This is a challenging task in case of workflows as they contain textual content as well as graphical structure. Current workflow search engines such as Yahoo Pipes! or myExperiment ignore the actual workflow specification and use metadata to create summaries. Workflows which lack metadata do not make good summaries even if they are useful and relevant as search criteria. This work investigates the possibility of creating meaningful and usable summaries or snippets based on structure and specification of workflows. We shall  (1) present relevant published work done regarding snippet building techniques (2) explain how we mapped current techniques to our work (3) describe how we identified techniques from interface design theory in order to make usable graphical interface (4) present implementation of two new algorithms for workflow graph compression and their complexity analysis (5) identify future work in our implementation and outline open research problems in snippet building field.

  • 281.
    Bhide, Priyanka
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    Design and Evaluation of Aceelerometer Based Mobile Authentication Techniques2017Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Smartphones’ usages are growing rapidly. Smart phone usages are not limited to the receiving/calling or SMSing anymore. People use smartphone for online shopping, searching various information in the web, bank transactions, games, different applications for different usages etc. Anything is possible by just having a smartphone and the internet. The more usages of the smartphone also increase keeping more secrete information about the user in the phone. The popularity is increasing and so is different ways to steal/hack the phones. There are many areas which require further investigation in the field of smartphone security and authentication.

    This thesis work evaluates the scope of different inbuilt sensors in smartphones for mobile authentication based techniques. The Android Operating system was used in the implementation phase. Android OS has many open source library and Services which have been used for the sensor identification using Java Android platform.

    Two applications using Accelerometer sensor and one using Magnetometer sensor were developed. Two foremost objectives of this thesis work were-1) To figure it out the possibilities of sensor based authentication technique. 2) To check the end user perception/opinion about the applications.

    Usability testing was conducted to gather the user’s assessments/vision of the applications. Two methods which were used for usability testing are named Magical move and Tapping. Users (Most of them) have shown interest and inclination towards tapping application. Although, some users were also expressed inhibitions using both sensor based methods.

  • 282.
    Bildtmark, Kim
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi.
    Jädersand, Robin
    Högskolan i Halmstad, Akademin för informationsteknologi.
    Security Awareness for Mobility: En studie om företagsmobilitet och de säkerhetsrisker som följer2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 283.
    Bilien, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Key Agreement for Secure Voice over IP2003Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis reviews the usual properties and requirements for key agreement protocols. It then focuses on MIKEY, a work-in-progress protocol designed to conduct key agreements for secure multimedia exchanges. The protocol was implemented and incorporated in a SIP user agent - minisip. This implementation was used to measure the additional delay required for key exchange during call establishment. Finally, some schemes are proposed regarding the use of MIKEY in advanced VoIP scenarios, such as conferences and terminal mobility.

  • 284.
    Billman, Johan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Hellström, Victor
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Abusing Keep-Alive Forwarding to flood a VANET: When safety messages become a safety risk2016Independent thesis Basic level (university diploma), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Cooperative Intelligent Transport Systems (C-ITS) enable vehicles to cooperate with each other and can be used to increase traffic safety and traffic flow. There are several standard initiatives for C-ITS, such as WAVE in the US, ARIB in Japan and ETSI ITS G5 in Europe.

    Decentralized Environment Notification Message (DENM) is a kind of message within ETSI TC ITS. DENMs are event-triggered, multi-hop notification messages that can be for- warded using Keep-Alive Forwarding (KAF).

    In this thesis, KAF is used to flood the network with DENMs sent from a single attack- ing vehicle. Using the simulation tools SUMO, OmNet++ and Veins, a highway scenario is studied. In the scenario, a vehicle sends out a DENM into a network that is being attacked by one other vehicle. Due to how KAF allows messages to be forwarded the other vehicles help flood the network. The results clearly indicate that KAF can be abused to create a Denial of Service (DoS) attack. After just a few seconds, the attack has introduced large de- lays and very high packet loss. The delay to receive a DENM is increased by several orders of magnitude and the packet loss reach unacceptable levels. By getting DENMs several seconds after they are needed, or by not getting them at all, could lead to traffic hazards. 

  • 285.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Parsapoor, Mahboobeh
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    A Framework and Architecture for a Cognitive Manager Based on a Computational Model of Human Emotional Learning2013Inngår i: Proceedings of SDR-WInnComm-Europe 2013: Wireless Innovation European Conference on Wireless Communications Technologies and Software Defined Radio / [ed] Lee Pucker, Kuan Collins & Stephanie Hamill, 2013, 64-72 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we propose an architecture for a cognitive engine that is based on the emotional learning cycle instead of the traditional cognitive cycle. The cognitive cycle that traditionally has been used as reference for cognitive radio is on the basis of the Unified Theories of Cognition (UTC) to model rational decision making in humans. UTC represents a rational goal-oriented decision-action made by an intelligent agent. However, the emotional cycle represents an emotional reaction-oriented cycle instead. These two models differ in function and structure of learning, decision making and optimization. In this work the structure of these two learning cycles are compared and a computational model for artificial emotional learning based engine is suggested.

  • 286.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Sjöberg, Katrin
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    A comparison of spatial energy consumption distribution for single- and mulihop wireless network architectures2004Konferansepaper (Fagfellevurdert)
  • 287.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Svensson, Bertil
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE).
    Knowledge Horizon - Dynamic limitations in a wireless ad hoc network2003Inngår i: SNCNW 2003 Swedish National Computer Networking Workshop 2003 on-line proceedings, 2003, 1-3 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we investigate the impact of node mobility in a wireless ad hoc network (WAHN). Especially we investigate the possibility to provide guaranteed services in a WAHN, i.e., the network topology predictability. We combine link expiration time (LET) estimation with information propagation speed (IPS) in a time-space diagram and as result an operation area is revealed. The result gives that a WAHN, where the nodes are mobile, has a knowledge horizon (KH), the distance of which is dependent on the mobility of the nodes. Beyond the KH, knowledge about the network state is impossible to achieve. Thus, we can not predict long distance network topology state when the node mobility is high.

  • 288.
    Bilstrup, Urban
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Wiberg, Per-Arne
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Routing protocol for wireless real-time multihop networks1999Konferansepaper (Fagfellevurdert)
  • 289.
    Bin, Yang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Using Six Sigma Methodology to improve the performance of the Shipment Test2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Competition and lead-time pressure motivates us to find new and better ways of continuously improving the output of our work. The emphasis on improvement in both efficiency and quality has become more and more significant in daily activities. The performance of Ericsson’s AXE/APZ products during shipment test phase is one such activity and is the focus of this thesis project. One of the essential principles of shipment testing is to ensure that the test campaigns finish on time. Over the last several decades companies have spent large amounts of time and money on improving test quality and efficiency. Unfortunately, the results have not always been as good as expected. It seems that it is very difficult to improve shipment testing performance using traditional test management methods.

    Motorola introduced Six Sigma in 1986 and achieved 5.4 Sigma level which help them saved 2.2 Billion dollars during the first six years. From Statistic aspect, it means only 3.4 defects per million opportunities. The Six Sigma methodology has been applied as a management philosophy focused on improving efficiency and performance during the shipment test period.

    This thesis gives an introduction to the Six Sigma approach, including the concepts of Six Sigma, its history, development, and methodology. More specifically the author uses the Define, Measure, Analyze, Improve, and Control (DMAIC) approach to evaluate the performance of Ericsson’s AXE/APZ Shipment Testing. This project goal was defined: Compare with the performance of 08AXE shipment test which 87% of test campaigns (2.68 sigma level) were finished on time, 3 sigma level in 09AXE shipment test which means 93%of the test campaigns will be finished on time has to be achieved.  The thesis measured the 08AXE shipment test performance and analyzed the lead time of test campaigns, found the root causes such as poor documents quality from the legacy project, lack of test resources, no system impact analysis. The thesis also provided a set of proposals for improvements and control of the improved process in order to ensure sustainable improved performance results. Finally 93% test campaigns were finished on time in 09AXE and project goal was fulfilled.

  • 290.
    Bjorklund, Svante
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Johansson, Tommy
    Swedish Def Res Agcy FOI, SE-58111 Linkoping, Sweden..
    Petersson, Henrik
    Swedish Def Res Agcy FOI, SE-58111 Linkoping, Sweden..
    Target Classification in Perimeter Protection with a Micro-Doppler Radar2016Inngår i: 2016 17TH INTERNATIONAL RADAR SYMPOSIUM (IRS), 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In security surveillance at the perimeter of critical infrastructure, such as airports and power plants, approaching objects have to be detected and classified. Especially important is to distinguish between humans, animals and vehicles. In this paper, micro-Doppler data (from movement of internal parts of the target) have been collected with a small radar of a low complexity and cost-effective type. From time-velocity diagrams of the data, some physical features have been extracted and used in a support vector machine classifier to distinguish between the classes "human", "animal" and "man-made object". Both the type of radar and the classes are suitable for perimeter protection. The classification result are rather good, 77% correct classification. Particularly interesting is the surprisingly good ability to distinguish between humans and animals. This also indicates that we can choose to have limitations in the radar and still solve the classification task.

  • 291.
    Bjorklund, Svante
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Petersson, Henrik
    Swedish Def Res Agcy FOI, SE-58111 Linkoping, Sweden..
    Hendeby, Gustaf
    Swedish Def Res Agcy FOI, SE-58111 Linkoping, Sweden.;Linkoping Univ, SE-58183 Linkoping, Sweden..
    Features for micro-Doppler based activity classification2015Inngår i: IET radar, sonar & navigation, ISSN 1751-8784, E-ISSN 1751-8792, Vol. 9, nr 9, 1181-1187 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Safety and security applications benefit from better situational awareness. Radar micro-Doppler signatures from an observed target carry information about the target's activity, and have potential to improve situational awareness. This article describes, compares, and discusses two methods to classify human activity based on radar micro-Doppler data. The first method extracts physically interpretable features from the time-velocity domain such as the main cycle time and properties of the envelope of the micro-Doppler spectra and use these in the classification. The second method derives its features based on the components with the most energy in the cadence-velocity domain (obtained as the Fourier transform of the time-velocity domain). Measurements from a field trial show that the two methods have similar activity classification performance. It is suggested that target base velocity and main limb cadence frequency are indirect features of both methods, and that they do often alone suffice to discriminate between the studied activities. This is corroborated by experiments with a reduced feature set. This opens up for designing new more compact feature sets. Moreover, weaknesses of the methods and the impact of non-radial motion are discussed.

  • 292.
    Bjurefors, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Measurements in opportunistic networks2012Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Opportunistic networks are a subset of delay tolerant networks where the contacts are unscheduled. Such networks can be formed ad hoc by wireless devices, such as mobile phones and laptops. In this work we use a data-centric architecture for opportunistic networks to evaluate data dissemination overhead, congestion in nodes' buffer, and the impact of transfer ordering. Dissemination brings an overhead since data is replicated to be spread in the network and overhead leads to congestion, i.e., overloaded buffers.

    We develop and implement an emulation testbed to experimentally evaluate properties of opportunistic networks. We evaluate the repeatability of experiments in the emulated testbed that is based on virtual computers. We show that the timing variations are on the order of milliseconds.

    The testbed was used to investigate overhead in data dissemination, congestion avoidance, and transfer ordering in opportunistic networks. We show that the overhead can be reduced by informing other nodes in the network about what data a node is carrying. Congestion avoidance was evaluated in terms of buffer management, since that is the available tool in an opportunistic network, to handle congestion. It was shown that replication information of data objects in the buffer yields the best results. We show that in a data-centric architecture were each data item is valued differently, transfer ordering is important to achieve delivery of the most valued data.

  • 293.
    Bjurefors, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för datorteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Opportunistic Networking: Congestion, Transfer Ordering and Resilience2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Opportunistic networks are constructed by devices carried by people and vehicles. The devices use short range radio to communicate. Since the network is mobile and often sparse in terms of node contacts, nodes store messages in their buffers, carrying them, and forwarding them upon node encounters. This form of communication leads to a set of challenging issues that we investigate: congestion, transfer ordering, and resilience.

    Congestion occurs in opportunistic networks when a node's buffers becomes full. To be able to receive new messages, old messages have to be evicted. We show that buffer eviction strategies based on replication statistics perform better than strategies that evict messages based on the content of the message.

    We show that transfer ordering has a significant impact on the dissemination of messages during time limited contacts. We find that transfer strategies satisfying global requests yield a higher delivery ratio but a longer delay for the most requested data compared to satisfying the neighboring node's requests.

    Finally, we assess the resilience of opportunistic networks by simulating different types of attacks. Instead of enumerating all possible attack combinations, which would lead to exhaustive evaluations, we introduce a method that use heuristics to approximate the extreme outcomes an attack can have. The method yields a lower and upper bound for the evaluated metric over the different realizations of the attack. We show that some types of attacks are harder to predict the outcome of and other attacks may vary in the impact of the attack due to the properties of the attack, the forwarding protocol, and the mobility pattern.

  • 294.
    Bjurefors, Fredrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Karaliopoulos, Markourios
    Rohner, Christian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Smith, Paul
    Theodoropoulos, George
    Gunningberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Resilience and Opportunistic Forwarding: Beyond Average Value Analysis2014Inngår i: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 48, nr SI, 111-120 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Opportunistic networks are systems with highly distributed operation, relying on the altruistic cooperation of highly heterogeneous, and not always software and hardware-compatible, user nodes. Moreover, the absence of central coordination and control makes them vulnerable to malicious attacks. In this paper, we study the resilience of popular forwarding protocols to a representative set of challenges to their normal operation. These include jamming locally disturbing message transfer between nodes, hardware/software failures and incompatibility among nodes rendering contact opportunities useless, and free-riding phenomena. We first formulate and promote the metric envelope concept as a tool for assessing the resilience of opportunistic forwarding schemes. Metric envelopes depart from the standard practice of average value analysis and explicitly account for the differentiated challenge impact due to node heterogeneity (device capabilities, mobility) and attackers’ intelligence. We then propose heuristics to generate worst- and best-case challenge realization scenarios and approximate the lower and upper bounds of the metric envelopes. Finally, we demonstrate the methodology in assessing the resilience of three popular forwarding protocols in the presence of the three challenges, and under a comprehensive range of mobility patterns. The metric envelope approach provides better insights into the level of protection path diversity and message replication provide against different challenges, and enables more informed choices in opportunistic forwarding when network resilience becomes important.

  • 295.
    Bjurefors, Fredrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Karaliopoulos, Merkourios
    Rohner, Christian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Smith, Paul
    Theodoropoulos, George
    Gunningberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Resilience and Opportunistic Forwarding: Beyond Average Value Analysis2013Inngår i: CHANTS '13 Proceedings of the 8th ACM MobiCom workshop on Challenged networks, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Opportunistic networks are systems with highly distributed operation, relying on the altruistic cooperation of heterogeneous, and not always software- and hardware-compatible user nodes. Moreover, the absence of central control makes them vulnerable to malicious attacks. In this paper, we take a fresh look at the resilience of opportunistic forwarding to these challenges. In particular, we introduce and promote the use of metric envelopes as a resilience assessment tool. Metric envelopes depart from the standard practice of average value analysis and explicitly account for the differentiated impact that a challenge may have on the forwarding performance due to node heterogeneity (device capabilities, mobility) and attackers’ intelligence. The use of metric envelopes is demonstrated in the case of three challenges: jamming, hardware/software failures and incompatibilities, and free-riding phenomena. For each challenge, we first devise heuristics to generate worst- and best-case realization scenarios that can approximate the metric envelopes. Then we derive the envelopes of common performance metrics for three popular forwarding protocols under a comprehensive range of mobility patterns. The metric envelope approach enables more informed choices in opportunistic forwarding whenever network resilience considerations become important. 

  • 296.
    Bjurén, Johan
    Högskolan i Skövde, Institutionen för informationsteknologi.
    USING CASE-BASED REASONING FOR PREDICTING ENERGY USAGE2013Independent thesis Advanced level (degree of Master (Two Years)), 30 poäng / 45 hpOppgave
    Abstract [en]

    In this study, the inability to in a future meet the electricity demand and the urge to change the consumption behavior considered. In a smart grid context there are several possible ways to do this. Means include ways to increase the consumer’s awareness, add energy storages or build smarter homes which can control the appliances. To be able to implement these, indications on how the future consumption will be could be useful. Therefore we look further into how a framework for short-term consumption predictions can be created using electricity consumption data in relation to external factors. To do this a literature study is made to see what kind of methods that are relevant and which qualities is interesting to look at in order to choose a good prediction method. Case Based Reasoning seemed to be able to be suitable method. This method was examined further and built using relational databases. After this the method was tested and evaluated using datasets and evaluation methods CV, MBE and MAPE, which have previously been used in the domain of consumption prediction. The result was compared to the results of the winning methods in the ASHRAE competition. The CBR method was expected to perform better than what it did, and still not as good as the winning methods from the ASHRAE competition. The result showed that the CBR method can be used as a predictor and has potential to make good energy consumption predictions. and there is room for improvement in future studies.

  • 297.
    Björklund, Daniel
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Implementation of a Software-Defined Radio Transceiver on High-Speed Digitizer/Generator SDR142012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis describes the specification, design and implementation of a software-defined radio system on a two-channel 14-bit digitizer/generator. The multi-stage interpolations and decimations which are required to operate two analog-to-digital converters at 800 megasamples per second (MSps) and two digital-to-analog converters at 1600 MSps from a 25 MSps software-side interface, were designed and implemented. Quadrature processing was used throughout the system, and a combination of fine-tunable low-rate mixers and coarse high-rate mixers were implemented to allow frequency translation across the entire first Nyquist band of the converters. Various reconstruction filter designs for the transmitter side were investigated and a cheap implementation was done through the use of programmable base-band filters and polynomial approximation.

  • 298.
    Björklund, Fredrik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Karlström, Elin
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Enabling Testing of Lateral Active Safety Functions in a Multi-rate Hardware in the Loop Environment2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    As the development of vehicles moves towards shorter development time, new ways of verifying the vehicle performance is needed in order to begin the verification process at an earlier stage. A great extent of this development regards active safety, which is a collection name for systems that help both avoid accidents and minimize the effects of a collision, e.g brake assist and steering control systems. Development of these active safety functions requires extensive testing and verification in order to guarantee the performance of the functions in different situations. One way of testing these functions is to include them in a Hardware in the Loop simulation, where the involved hardware from the real vehicle are included in the simulation loop.

    This master thesis investigates the possibility to test lateral active safety functions in a hardware in the loop simulation environment consisting of multiple subsystems working on different frequencies. The subsystems are all dependent of the output from other subsystems, forming an algebraic loop between them. Simulation using multiple hardware and subsystems working on different frequencies introduces latency in the simulation. The effect of the latency is investigated and proposed solutions are presented. In order to enable testing of lateral active safety functions, a steering model which enables the servo motor to steer the vehicle is integrated in the simulation environment and validated.

  • 299.
    Björklund, Svante
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Grahn, Per
    Nelander, Anders
    Pettersson, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Measurement of Rank and Other Properties of Direct and Scattered Signals2016Inngår i: International Journal of Antennas and Propagation, ISSN 1687-5869, E-ISSN 1687-5877, Vol. 2016, 5483547Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have designed an experiment for low-cost indoor measurements of rank and other properties of direct and scattered signals with radar interference suppression in mind. The signal rank is important also in many other applications, for example, DOA (Direction of Arrival) estimation, estimation of the number of and location of transmitters in electronic warfare, and increasing the capacity in wireless communications. In real radar applications, such measurements can be very expensive, for example, involving airborne radars with array antennas. We have performed the measurements in an anechoic chamber with several transmitters, a receiving array antenna, and a moving reflector. Our experiment takes several aspects into account: transmitted signals with different correlation, decorrelation of the signals during the acquisition interval, covariance matrix estimation, noise eigenvalue spread, calibration, near-field compensation, scattering in a rough surface, and good control of the influencing factors. With our measurements we have observed rank, DOA spectrum, and eigenpatterns of direct and scattered signals. The agreement of our measured properties with theoretic and simulated results in the literature shows that our experiment is realistic and sound. The detailed description of our experiment could serve as help for conducting other well-controlled experiments. © Copyright 2016 Svante Björklund et al.

  • 300.
    Björklund, Ulf
    KTH, Tidigare Institutioner, Teleinformatik.
    Understanding the Performance of the Linux IPv6 Implementation1998Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The new version of the Internet protocol, IP version 6, will eventually replace the current version IP version 4. Before that change can take place the different implementations of IPv6 must be able to perform at least as well as their predecessors, The implementation that is considered here is that of the Linux operating system. All measurements considers native IPv6, e.g. no tunneling in IPv4 packets.

    A small network of two computers was set up on which the performance tests were performed. Throughput and response times were measured on both Ethernet and Fast Ethernet. The conclusions are that IPv6 performs almost as well as IPv4 in both cases. IPv4's slight advantage is due to the fact that it has less overhead on the network since the header is smaller.

    Later a connection to the 6bone is setup. It is run on an ATM network. The performance across that network is also tested.

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