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Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 251.
    Ben Slimane, Slimane
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    A low complexity antenna diversity receiver for OFDM based systems2001Inngår i: IEEE International Conference on Communications, 2001, s. 1147-1151Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A low complexity antenna diversity architecture with a new combining technique suitable for orthogonal frequency division (OFDM) based systems is introduced in this paper. For a two branch antenna diversity, this structure requires only one FFT at the receiver and allows optimum maximum ratio combining. For systems with a higher number of antennas, the number of required FFTs when using such technique is reduced by half as compared to the conventional case where a different FFT is used for each receive antenna. As a result a considerable reduction in processing complexity is obtained especially for systems with high number of subcarriers. This method can also be seen as a way of increasing the number of antennas in OFDM transceivers without any major complexity increase. Thus, a considerable increase in diversity gain can be achieved

  • 252.
    Ben Slimane, Slimane
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Bounds on the Distribution of a Sum of Independent Lognormal Random Variables2001Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 49, nr 6, s. 975-978Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The distribution function of a sum of lognormal random variables (RVs) appears in several communication problems. Approximations are usually used for such distribution as no closed form nor bounds exist. Bounds can be very useful in assessing the performance of any given system. In this letter, we derive upper and lower bounds on the distribution function of a sum of independent lognormal RVs. These bounds are given in a closed form and can be used in studying the performance of cellular radio and broadcasting systems.

  • 253.
    Ben Slimane, Slimane
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Channel estimation for HIPERLAN/2 with transmitter diversity2002Konferansepaper (Fagfellevurdert)
  • 254.
    Ben Slimane, Slimane
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Channel estimation for HIPERLAN/2 with transmitter diversity2002Inngår i: 2002 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-5, CONFERENCE PROCEEDINGS, 2002, s. 26-30Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we propose a channel estimation technique for OFDM based systems, such as HIPERLAN/2 and IEEE 802.11a, with transmitter diversity. The proposed technique estimates all channel frequency responses, corresponding to each transmitter and receiver antenna pair, required for space-time processing In this OFDM based system. This technique is able to extract the channel state Information for two transmitter antennas using the same preamble as defined in the standard of HIPERLAN/2. The feasibility of this channel estimation method Is made possible by exploiting the structure of the OFDM modulation scheme. The results showed that the accuracy provided by this proposed method is comparable to that obtained when a single transmitter antenna is used.

  • 255.
    Ben Slimane, Slimane
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Channel estimation for OFDM based systems with transmitter diversity2002Inngår i: 2002 IEEE International Conference on Systems, Man and Cybernetics,, 2002, s. 397-402Konferansepaper (Fagfellevurdert)
  • 256.
    Ben Slimane, Slimane
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Peak-to-average power ratio reduction of OFDM signals using broadband pulse shaping2002Inngår i: IEEE 56TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2002, VOLS 1-4, PROCEEDINGS, 2002, s. 889-893Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Orthogonal Frequency Division Multiplexing (OFDM) techniques allow the transmission of high data rates over broadband radio channels subject to multipath fading without the need for powerful channel equalization. However, they are very sensitive to nonlinear effects due to the high Peak-to-Average Power Ratio (PAPR) owned by the transmitted signal. This paper proposes an efficient technique for reducing the PAPR of OFDM signals. The proposed technique is very effective and flexible. The method avoids the use of extra Inverse Fast Fourier Transformations (IFFTs) as was done in some previously published techniques but instead is based on a proper selection of the time waveforms of the different sub-carriers of the OFDM modulation scheme. Thus, its implementation complexity is much low in comparison to the previous published methods. A closed form relation between the maximum PAPR and the used pulse shaping waveform is derived. The obtained results show that with broadband pulse shaping, the PAPR of OFDM modulated signals can be made very close to that of single carrier signals. The improved statistics of the PAPR in the transmitted signal is demonstrated through numerical results for some sets of time waveforms. The significant improvement in PAPR given by the present technique permits to reduce the complexity and cost of the transmitter significantly. In that, pulse shaping can be used not only to shape the spectrum of the transmitted signal but also to reduce its PAPR.

  • 257.
    Ben Slimane, Slimane
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Janssen, G.J.M.
    Delft University.
    Power optimization of M-PSK cochannel signals for a narrowband multiuser detector2001Inngår i: IEEE Pacific RIM Conference on Communications, Computers, and Signal Processing - Proceedings, 2001, s. 247-250Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An analytical method is presented to determine the optimum received power values for multiple cochannel multilevel phase-shift-keying (M-PSK) modulated signals. The aim is to achieve equal symbol error probability (SEP) for each of the signals when applying a narrowband multiuser detector based on successive cancellations. Power relations based on two approximations are derived and used to compute the average SEP for the different cochannel signals. The derived power relations are also compared against optimum power relations obtained through computer simulations

  • 258.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    A doubly stochastic Poisson model for self-similar traffic1995Inngår i: IEEE International Conference on Communications, 1995, s. 456-460Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a data traffic model capable of describing the long-range dependence and self-similar burstiness structure found in measurement studies of packet data traffic. The model introduced is based on doubly stochastic Poisson processes. The intensity of arrivals is modeled as a continuous stochastic process. This process satisfies most of the properties found in the measurement studies, namely long-range dependence and self-similarity. The generality and simplicity of this model makes it attractive in data traffic modeling

  • 259.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Coded quadrature pulse-overlapping modulation techniques for personal communications1992Inngår i: 1st International Conference on Universal Personal Communications, 1992. ICUPC '92 Proceedings, 1992, s. 11-03/1-11-03/5Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Hard-limited quadrature pulse-overlapping modulation (QPOM) techniques have a constant envelope, good spectral properties and good performance especially in fading channels. These modulation techniques are suitable to applications using nonlinear or saturated power amplifiers to obtain high power and bandwidth efficiencies. A technique to combine convolutional codes and QPOM schemes to further improve its performance in fading channels is introduced and evaluated. At first, the QPOM scheme is decomposed into an encoder followed by a memoryless modulator. Then, the binary convolutional encoder is concatenated to the QPOM encoder and considered as one entity to be optimized. Performance of the coded QPOM scheme is analyzed and compared to uncoded QPOM and coded QPSK schemes

  • 260.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    IJF-OQPSK modulation schemes with MLSE receivers for portable/mobile communications1992Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A receiver structure for constant enveloped IJF-OQPSK modulation under fading channel conditions is introduced. Its performance in AWGN and Rayleigh fading channels was analyzed and verified by computer simulations. Results show the relation between the performance of the system and the memory introduced by the double-interval overlapping pulse shape. By properly using this memory, it is possible to achieve superior performance compared to conventional schemes. Even though no coding has been used, comparable results to coded schemes was obtained with no extra redundancy. Therefore, the complexity caused by multilevel modulation can be avoided, and transmission of signals with compact spectrum and good performance is possible. The constant envelope, compact spectrum, superior performance in fading channels and low complexity make the hardlimited IJF-OQPSK scheme a good choice for portable/mobile communications, to achieve low cost, small size, and high power and bandwidth efficiencies

  • 261.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Maximum likelihood sequence estimation of quadrature pulse-overlapping modulated signals for portable/mobile satellite1992Inngår i: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 10, nr 8Artikkel i tidsskrift (Fagfellevurdert)
  • 262.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Performance of 16-QAM signals on a fading mobile satellite channel1994Inngår i: AEU - International Journal of Electronics and Communications, ISSN 1434-8411, E-ISSN 1618-0399, Vol. 48, nr 2, s. 68-75Artikkel i tidsskrift (Fagfellevurdert)
  • 263.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Performance of 16-QPOM signals on a fading mobile satellite channel1993Inngår i: Proceedings of the IEEE 1993 Pacific Rim Conference on Communications, Computers and Signal Processing, 1993, s. 674-677Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The authors present a maximum likelihood sequence estimation (MLSE) receiver structure for both linear and hard-limited 16-quadrature pulse overlapping modulation (QPOM) schemes. Using this structure, the performance of these schemes over shadowed Rician fading channels is studied. The structure of linear 16-QPOM schemes allowed the use of independent decoding for in-phase and quadrature components of the transmitted signal, thus reducing considerably the complexity of the MLSE receiver. The hard-limited 16-QPOM scheme used two hard-limited QPOM schemes in parallel. It is shown that an optimum MLSE receiver for this type of signal needs to consider both in-phase and quadrature components at the same time. Using the MLSE receiver, both schemes outperform conventional coherent 16-quadrature amplitude modulation (QAM)

  • 264.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Performance of 16-QPOM signals on a fading mobile satellite channel1993Inngår i: Proceedings of the IEEE Global Telecommunications Conference, IEEE , 1993, s. 1787-1791Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Presents the bit error probability of 16-QPOM schemes over mobile satellite shadowed Rician fading channels. An upper bound on the pairwise error probability is derived, and then combined with the transfer function bounding technique. The derived upper bound is given in a closed form without the need of any numerical integration. This upper bound is then used to evaluate the performance of both linear and hard-limited 16-QPOM signals. Simulation results are also performed to verify the analytical results

  • 265.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Performance of quadrature pulse-overlapping modulated signals in Rayleigh fading channels1991Inngår i: IEEE Global Telecommunications Conference and Exhibition, 1991, s. 1802-1806Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The authors discuss the average bit error probability of constant envelope quadrature pulse-overlapping modulation and maximum likelihood Viterbi decoding in a Rayleigh fading channel. The quadrature pulse-overlapping modulation is first decomposed into a linear encoder followed by a memoryless modulator. An upper bound on the average bit error probability as a function of the transfer function of the linear encoder is then developed under the assumption of using the Viterbi decoder with perfect fading amplitude measurement. Tightness of the bound was examined by means of computer simulation. A performance comparison with conventional quadrature phase shift keying is also provided

  • 266.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Quadrature Pulse-Overlapping Modulation Techniques1994Inngår i: Coded-Modulation Techniques for Fading Channels / [ed] S. Hamidreza Jamali, Tho Le-Ngoc, Kluwer Academic Publishers , 1994Kapittel i bok, del av antologi (Fagfellevurdert)
  • 267.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Tight bounds on the error probability of coded modulation schemes in Rayleigh fading channels1994Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a tight upper bound on the bit error performance of coded modulation schemes in Rayleigh fading channels. Upper and lower bounds on the pairwise error probability are first derived. The upper bound is then expressed in a product form to be used with the transfer function bounding technique. This upper bound has the same simplicity as the union-Chernoff bound while providing closer results to the exact expression. Examples for 4-state and 8-state TCM 8PSK schemes are also given to illustrate the tightness and the application of this upper bound

  • 268.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Tight Bounds on the Error Probability of Coded Modulation Schemes in Rayleigh Fading Channels1995Inngår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 44, nr 1, s. 121-130Artikkel i tidsskrift (Fagfellevurdert)
  • 269.
    Bengtsson, Hoai
    et al.
    Viktoria Swedish ICT, Gothenburg, Sweden.
    Chen, Lei
    Viktoria Swedish ICT, Gothenburg, Sweden.
    Voronov, Alexey
    Viktoria Swedish ICT, Gothenburg, Sweden.
    Englund, Cristofer
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR Centrum för tillämpade intelligenta system (IS-lab). Viktoria Swedish ICT, Gothenburg, Sweden.
    Interaction Protocol for Highway Platoon Merge2015Inngår i: 2015 IEEE 18th International Conference on Intelligent Transportation Systems / [ed] Lisa O’Conner, Los Alamitos: IEEE, 2015, s. 1971-1976, artikkel-id 7313411Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An interaction protocol for cooperative platoon merge on highways is proposed. The interaction protocol facilitates a challenge scenario for the Grand Cooperative Driving Challenge (GCDC) 2016, where two platoons running on separate lanes merge into one platoon due to a roadwork in one of the lanes. Detailed interaction procedures, described with state machines of each vehicle are presented. A communication message set is designed to support platoon controllers to perform safe and efficient manoeuvres. © 2015 IEEE.

  • 270. Bengtsson, Hoai
    et al.
    Chen, Lei
    Voronov, Alexey
    Englund, Cristofer
    RISE., Swedish ICT, Viktoria.
    Interaction Protocol for Highway Platoon Merge2015Inngår i: Intelligent Transportation Systems (ITSC), 2015 IEEE 18th International Conference on, 2015Konferansepaper (Fagfellevurdert)
  • 271.
    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.

  • 272.
    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.

  • 273.
    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.

  • 274.
    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.

  • 275. 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.

  • 276. 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, E-ISSN 1557-7325, Vol. 20, nr 5, s. 30-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.

  • 277.
    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)
  • 278. 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.

  • 279.
    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, s. 17-22Konferansepaper (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.

  • 280. 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, s. 1-9Konferansepaper (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.

  • 281.
    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.

  • 282.
    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, s. 1479-1483Konferansepaper (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.

  • 283.
    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, s. 1911-1916Artikkel 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".

  • 284.
    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.

  • 285.
    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.

  • 286.
    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.

  • 287.
    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, s. 045020-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.

  • 288.
    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, s. 329-332Konferansepaper (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.

  • 289.
    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, s. 2902-2914Artikkel 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.

  • 290.
    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, s. 4509-4521Artikkel 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.

  • 291.
    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.

  • 292.
    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.

  • 293.
    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.

  • 294.
    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.

  • 295.
    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.

  • 296.
    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)
  • 297.
    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.

  • 298.
    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, s. 864-868Konferansepaper (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.

  • 299.
    Besharat Pour, Shiva
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Li, Qi
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Connecting Silos: Automation system for thesis processing in Canvas and DiVA2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    As the era of digitalization dawns, the need to integrate separate silos into a synchronized connected system is becoming of ever greater significance. This thesis focuses on the Canvas Learning Management System (LMS) and the Digitala vetenskapliga arkive (DiVA) as examples of separate silos.

    The thesis presents several methods of automating document handling associated with a degree project. It exploits the fact that students will submit their thesis to their examiner via Canvas. Canvas is the LMS platform used by students to submit all their coursework. When the examiner approves the thesis, it will be archived in DiVA and optionally published on DiVA. DiVA is an institutional repository used for research publications and student theses.

    When manually archiving and publishing student theses on DiVA several fields need to be filled in. These fields provide meta data for the thesis itself. The content of these fields (author, title, keywords, abstract, …) can be used when searching via the DiVA portal. It might not seem like a massive task to enter this meta data for an individual thesis; however, given the number of theses that are submitted every year, this process takes a large amount of time and effort. Moreover, it is important to enter this data correctly, which is difficult when manually doing this task. Therefore, this thesis project seeks to automate this process for future theses.

    The proposed solution parses PDF documents and uses information from the LMS in order to automatically generate a cover for the thesis and fill in the required DiVA meta data. Additionally, information for inserting an announcement of the student's oral thesis presentation into a calendar system will be provided. Moreover, the data in each case will be checked for correctness and consistency.

    Manually filling in DiVA fields in order to publish theses has been a quite demanding and time-consuming process. Thus, there is often a delay before a thesis is published on DiVA. Therefore, this thesis project’s goal is to provide KTH with an automated means to handle thesis archiving and publication on DiVA, while doing so more efficiently, and with fewer errors. The correctness of the extracted meta data will be evaluated by comparing the results to the previously entered meta data for theses that have previously been achieved in DiVA. The automated process has been calculated to take roughly 50 seconds to prepare the information needed to publish a thesis to DiVA with ~71% accuracy, compared with 1 hour and 34% accuracy in the previous manual method.

  • 300.
    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.

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