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  • 151.
    Ingemarsson, Ingemar
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Encryption in Telefax1978Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Our standpoint is that the basic need for information security in TELETEX is provided by the data network used together with the possibility to encrypt the messages in the terminals, thereby protecting the messages from information loss. Means for detection of information destruction or change and f or verification at unencrypted data may then be provided for by the user of the TELETEX system.

  • 152.
    Ingemarsson, Ingemar
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Några reflektioner kring elektroniska betalningsmedel1979Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    De här nedskrivna tankarna är en frukt av diskussioner med bankfolk och datasäkerhetsforskare rörande olika problem med elektroniska betalningsmedel. De utgör ett försök att formulera de mest grundläggande egenskaperna i viss mån för betalningsmedel i allmänhet och för elektroniska i synnerhet. Syftet är att skapa diskussion kring de problem (främst säkerhetsproblem) som en allmän användning av elektroniska betalningsmedel kan ge upphov till.

  • 153.
    Interdonato, Giovanni
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Frenger, Pål
    Ericsson Research, Ericsson AB, Linköping, Sweden.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Scalability Aspects of Cell-Free Massive MIMO2019Ingår i: 2019 IEEE International Conference on Communications (ICC), Proceedings Shanghai, China 20–24 May 2019, Institute of Electrical and Electronics Engineers (IEEE), 2019, s. 1-6Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ubiquitous cell-free massive MIMO (multiple-input multiple-output) combines massive MIMO technology and user-centric transmission in a distributed architecture. All the access points (APs) in the network cooperate to jointly and coherently serve a smaller number of users in the same time-frequency resource. However, this coordination needs significant amounts of control signalling which introduces additional overhead, while data co-processing increases the back/front-haul requirements. Hence, the notion that the “whole world” could constitute one network, and that all APs would act as a single base station, is not scalable. In this study, we address some system scalability aspects of cell-free massive MIMO that have been neglected in literature until now. In particular, we propose and evaluate a solution related to data processing, network topology and power control. Results indicate that our proposed framework achieves full scalability at the cost of a modest performance loss compared to the canonical form of cell-free massive MIMO.

  • 154.
    Interdonato, Giovanni
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten. Ericsson Research, Linköping, Sweden.
    Frenger, Pål
    Ericsson Research, Linköping, Sweden.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Utility-based Downlink Pilot Assignment in Cell-Free Massive MIMO2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a strategy for orthogonal downlink pilot assignment in cell-free massive MIMO (multiple-input multiple-output) that exploits knowledge of the channel state information, the channel hardening degree at each user, and the mobility conditions for the users. These elements, properly combined together, are used to define a user pilot utility metric, which measures the user's real need of a downlink pilot for efficient data decoding. The proposed strategy consists in assigning orthogonal downlink pilots only to the users having a pilot utility metric exceeding a predetermined threshold. Instead, users that are not assigned with an orthogonal downlink pilot decode the data by using the statistical channel state information. The utility-based approach guarantees higher downlink net sum throughput, better support both for high-speed users and shorter coherent intervals than prior art approaches.

  • 155.
    Interdonato, Giovanni
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Ngo, Hien Quoc
    Queen’s University Belfast, UK.
    Frenger, Pål
    Ericsson Research, Ericsson AB, Linköping, Sweden.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Downlink Training in Cell-Free Massive MIMO: A Blessing in Disguise2019Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 18, nr 11, s. 5153-5169Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cell-free Massive MIMO (multiple-input multipleoutput) refers to a distributed Massive MIMO system where all the access points (APs) cooperate to coherently serve all the user equipments (UEs), suppress inter-cell interference and mitigate the multiuser interference. Recent works 1, 2 demonstrated that, unlike co-located Massive MIMO, the channel hardening is, in general, less pronounced in cell-free Massive MIMO, thus there is much to benefit from estimating the downlink channel. In this study, we investigate the gain introduced by the downlink beamforming training, extending the analysis in 1 to non-orthogonal uplink and downlink pilots. Assuming singleantenna APs, conjugate beamforming and independent Rayleigh fading channel, we derive a closed-form expression for the peruser achievable downlink rate that addresses channel estimation errors and pilot contamination both at the AP and UE side. The performance evaluation includes max-min fairness power control, greedy pilot assignment methods, and a comparison between achievable rates obtained from different capacitybounding techniques. Numerical results show that downlink beamforming training, although increases pilot overhead and introduces additional pilot contamination, improves significantly the achievable downlink rate. Even for large number of APs, it is not fully efficient for the UE relying on the statistical channel state information for data decoding.

  • 156.
    Islam, Hasan M. A.
    et al.
    Aalto Univ, Finland.
    Lagutin, Dmitrij
    Aalto Univ, Finland.
    Lukyanenko, Andrey
    Aalto Univ, Finland.
    Gurtov, Andrei
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Yla-Jaaski, Antti
    Aalto Univ, Finland.
    CIDOR: Content Distribution and Retrieval in Disaster Networks for Public Protection2017Ingår i: 2017 IEEE 13TH INTERNATIONAL CONFERENCE ON WIRELESS AND MOBILE COMPUTING, NETWORKING AND COMMUNICATIONS (WIMOB), IEEE , 2017, s. 324-333Konferensbidrag (Refereegranskat)
    Abstract [en]

    Information-Centric Networking (ICN) introduces a paradigm shift from a host centric communication model for Future Internet architectures. It supports the retrieval of a particular content regardless of the physical location of the content. Emergency network in a disaster scenario or disruptive network presents a significant challenge to the ICN deployment. In this paper, we present a Content dIstribution and retrieval framework in disaster netwOrks for public pRotection (CIDOR) which exploits the design principle of the native CCN architecture in the native Delay Tolerant Networking (DTN) architecture. We prove the feasibility and investigate the performance of our proposed solution using extensive simulation with different classes of the DTN routing strategies in different mobility scenarios. The simulation result shows that CIDOR can reduce the content retrieval time up to 50% while the response ratio is close to 100%.

  • 157.
    Jacob, Kane
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik.
    Gudey, Bala Bhaskar
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik.
    Co-Design of Antenna and LNA for 1.7 - 2.7 GHz2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In a radio frequency (RF) system, the front-end of a radio receiver consists of an active antenna arrangement with a conducting mode antenna along with an active circuit. This arrangement helps avoid losses and SNR degradation due to the use of a coaxial cable. The active circuit is essentially an impedance matching network and a low noise amplification (LNA) stage. The input impedance of the antenna is always different from the source impedance required to be presented at the LNA input for maximum power gain and this gives rise to undesired reflections at the antenna-LNA junction. This necessitates a matching network that provides the impedance matching between the antenna and the LNA at a central frequency (CF). From the Friis formula it is seen that the total noise figure (NF) of the system is dependent on the noise figure and gain of the first stage. So, by having an LNA that provides a high gain (typically >15 dB) which inserts minimum possible noise (desirably < 1 dB), the overall noise figure of the system can be maintained low. The LNA amplifies the signal to a suitable power level that will enable the subsequent demodulation and decoding stages to efficiently recover the original signal. The antenna and the LNA can be matched with each other in two possible ways. The first approach is the traditional method followed in RF engineering where in both the antenna and LNA are matched to 50 W terminations and connected to each other. In this classical method, the antenna and LNA are matched to 50 W at the CF and does not take into account the matching at other frequencies in the operation range. The second approach employs a co-design method to match the antenna and LNA without a matching network or with minimum possible components for matching. This is accomplished by varying one or more parameters of either the antenna or LNA to control the impedances and ultimately achieve a matching over a substantial range of frequencies instead at the CF alone. The co-design method is shown to provide higher gain and a lower NF with reduced number of components, cost and size as compared to the classical method.

    The thesis work presented here is a study, design and manufacturing of an antenna-LNA module for a wide frequency range of 1.7 GHz – 2.7 GHz to explore the gain and NF improvements in the co-design approach. Planar micro strip patch antennas and GaAs E-pHEMT transistor based LNA’s are designed and the matching and co-design are simulated to test the gain and NF improvements. Furthermore, fully functional prototypes are developed with Roger R04360 substrate and the results from simulations and actual measurements are compared and discussed. 

  • 158.
    Jang, Jeong Keun
    et al.
    Dongbu Hitek, South Korea.
    Kim, Ho Keun
    Ajou University, South Korea.
    Sunwoo, Myung Hoon
    Ajou University, South Korea.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    Area-efficient scheduling scheme based FFT processor for various OFDM systems2018Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This paper presents an area-efficient fast Fouriertransform (FFT) processor for orthogonal frequency-division multiplexing systems based on multi-path delay commutator architecture. This paper proposes a data scheduling scheme to reduce the number of complex constant multipliers. The proposed mixed-radix multi-path delay commutator FFT processor can support 128-, 256-, and 512-point FFT sizes. The proposed processor was synthesized using the Samsung 65-nm CMOS standard cell library. The proposed processor with eight parallel data paths can achieve a high throughput rate of up to 2.64 GSample/s at 330 MHz.

  • 159.
    Jang, Jeong Keun
    et al.
    Dongbu Hitek, South Korea.
    Kim, Ho Keun
    Ajou Univ, South Korea.
    Sunwoo, Myung Hoon
    Ajou Univ, South Korea.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Area-Efficient Scheduling Scheme Based FFT Processor for Various OFDM Systems2018Ingår i: 2018 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS 2018), IEEE , 2018, s. 338-341Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an area-efficient fast Fourier transform (FFT) processor for orthogonal frequency-division multiplexing systems based on multi-path delay commutator architecture. This paper proposes a data scheduling scheme to reduce the number of complex constant multipliers. The proposed mixed-radix multi-path delay commutator FFT processor can support 128-, 256-, and 512-point FFT sizes. The proposed processor was synthesized using the Samsung 65-nm CMOS standard cell library. The proposed processor with eight parallel data paths can achieve a high throughput rate of up to 2.64 GSample/s at 330 MHz.

  • 160.
    Janson, Robert
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Mottaghi, Amir
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    FPGA-design av en STDM-baserad multiplexer för seriell multiprotokollskommunikation2012Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The remotely operated underwater vehicles that the client develops have needs of different kinds of data channels. In order to minimize the need of physical cable between the control unit and a ROV, a multiplex protocol has been developed. The protocol has been designed with the aim of using the bandwidth of the transferring link as efficient as possible.

    The different kinds of data channels used during this thesis project is; RS232, RS485 and CAN. ROM and FIFO-memories have been used to be able to effectively manage the different data channels. All the reading and sending of these channels have been implemented in FPGA-technology, the coding is made generic so that it will be easier to add more channels to the system in the future.

    The multiplex protocol is a modified version of the method STDM and it is a proprietary protocol. Calculations has been made in MatLab to ensure that the protocol does not exceed the maximal bandwidth that is available. The protocol utilizes the error-detecting technique CRC for the purpose of error detection.

    A PCB has been developed during this thesis project, the PCB is made so that the different data channels have connection with the FPGA circuit.

  • 161.
    Jaoua, Mohamed
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem.
    Development of an FPGA-based High-Speed Wireless Communication System in the 60GHz Frequency Band For CERN facilities and 5G deployment2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The work is devoted in the development and the exploration of the capabilities of the state of art unlicensed 60GHz (V-Band) mm-wave band that has raised so much interest and attention from numerous companies and laboratories for implementing Multi-gigabit communications [17] and especially for the 5th generation of cellular network and wireless systems. Implementing a high wireless data transfer system requires a high bandwidth and the one around the 60GHz frequency turned out to be a very promising candidate [13]. In this thesis, different protocols were investigated and simulated on MATLAB and implemented on low-cost Field-Programmable Gate Arrays (FPGAs) in order to test its performance with different transmission protocols and systems and insure a robust communication system at the frequency band around 60GHz. Furthermore, the system was tested with a series of different binary sequences such as pseudo-random bi-nary sequences (PRBS-7, PRBS-15, PRBS-23 and PRBS-31) and a high data rate communication link also in the design. The link has been tested in the lab environment and two systems have successfully achieved a relatively low bit-error rate.

  • 162.
    Jin, Di
    et al.
    Technical University Darmstadt, Germany.
    Yin, Feng
    Ericsson AB, Sweden.
    Fritsche, Carsten
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Zoubir, Abdelhak M.
    Technical University Darmstadt, Germany.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Efficient Cooperative Localization Algorithm in LOS/NLOS Environments2015Ingår i: Proc. 23rd European Signal Processing Conference (EUSIPCO), Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 185-189Konferensbidrag (Refereegranskat)
    Abstract [en]

    The well-known cooperative localization algorithm, ‘sum-product algorithm over a wireless network’ (SPAWN) hastwo major shortcomings, a relatively high computationalcomplexity and a large communication load. Using the Gaus-sian mixture model with a model selection criterion and thesigma-point (SP) methods, we propose the SPAWN-SP toovercome these problems. The SPAWN-SP easily accommo-dates different localization scenarios due to its high flexibilityin message representation. Furthermore, harsh LOS/NLOSenvironments are considered for the evaluation of coopera-tive localization algorithms. Our simulation results indicatethat the proposed SPAWN-SP demonstrates high localizationaccuracy in different localization scenarios, thanks to its highflexibility in message representation.

  • 163.
    Jingya, Li
    et al.
    Chalmers University of Technology,Gothenburg, Sweden.
    Björnson, Emil
    KTH Royal Institute of Technology, Sweden; Supelec, France.
    Svensson, Tommy
    Chalmers University of Technology,Gothenburg, Sweden.
    Eriksson, Thomas
    Chalmers University of Technology,Gothenburg, Sweden,.
    Debbah, Merouane
    CentraleSupelec, France.
    Joint Precoding and Load Balancing Optimization for Energy-Efficient Heterogeneous Networks2015Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 14, nr 10, s. 5810-5822Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper considers a downlink heterogeneous network, where different types of multiantenna base stations (BSs) communicate with a number of single-antenna users. Multiple BSs can serve the users by spatial multiflow transmission techniques. Assuming imperfect channel state information at both BSs and users, the precoding, load balancing, and BS operation mode are jointly optimized for improving the network energy efficiency. We minimize the weighted total power consumption while satisfying quality-of-service constraints at the users. This problem is nonconvex, but we prove that for each BS mode combination, the considered problem has a hidden convexity structure. Thus, the optimal solution is obtained by an exhaustive search over all possible BS mode combinations. Furthermore, by iterative convex approximations of the nonconvex objective function, a heuristic algorithm is proposed to obtain a suboptimal solution of low complexity. We show that although multicell joint transmission is allowed, in most cases, it is optimal for each user to be served by a single BS. The optimal BS association condition is parameterized, which reveals how it is impacted by different system parameters. Simulation results indicate that putting a BS into sleep mode by proper load balancing is an important solution for energy savings.

  • 164.
    Jogenfors, Jonathan
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska fakulteten.
    Breaking the Unbreakable: Exploiting Loopholes in Bell’s Theorem to Hack Quantum Cryptography2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    En viktig konsekvens av kvantmekaniken är att okända kvanttillstånd inte kan klonas. Denna insikt har gett upphov till kvantkryptering, en metod för två parter att med perfekt säkerhet kommunicera hemligheter. Ett komplett bevis för denna säkerhet har dock låtit vänta på sig eftersom en attackerare i hemlighet kan manipulera utrustningen så att den läcker information. Som ett svar på detta utvecklades apparatsoberoende kvantkryptering som i teorin är immun mot sådana attacker.

    Apparatsoberoende kvantkryptering har en mycket högre grad av säkerhet än vanlig kvantkryptering, men det finns fortfarande ett par luckor som en attackerare kan utnyttja. Dessa kryphål har tidigare inte tagits på allvar, men denna avhandling visar hur även små svagheter i säkerhetsmodellen läcker information till en attackerare. Vi demonstrerar en praktisk attack där attackeraren aldrig upptäcks trots att denne helt kontrollerar systemet. Vi visar också hur kryphålen kan förhindras med starkare säkerhetsbevis.

    En annan tillämpning av kvantmekanikens förbud mot kloning är pengar som använder detta naturens egna kopieringsskydd. Dessa kvantpengar har helt andra egenskaper än vanliga mynt, sedlar eller digitala banköverföringar. Vi visar hur man kan kombinera kvantpengar med en blockkedja, och man får då man en slags "kvant-Bitcoin". Detta nya betalningsmedel har fördelar över alla andra betalsystem, men nackdelen är att det krävs en kvantdator.

    Delarbeten
    1. Energy-time entanglement, elements of reality, and local realism
    Öppna denna publikation i ny flik eller fönster >>Energy-time entanglement, elements of reality, and local realism
    2014 (Engelska)Ingår i: Journal of Physics A: Mathematical and Theoretical, ISSN 1751-8113, E-ISSN 1751-8121, Vol. 47, nr 42, s. 424032-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The Franson interferometer, proposed in 1989 (Franson 1989 Phys. Rev. Lett. 62 2205-08), beautifully shows the counter-intuitive nature of light. The quantum description predicts sinusoidal interference for specific outcomes of the experiment, and these predictions can be verified in experiment. In the spirit of Einstein, Podolsky, and Rosen it is possible to ask if the quantum-mechanical description (of this setup) can be considered complete. This question will be answered in detail in this paper, by delineating the quite complicated relation between energy-time entanglement experiments and Einstein-Podolsky-Rosen (EPR) elements of reality. The mentioned sinusoidal interference pattern is the same as that giving a violation in the usual Bell experiment. Even so, depending on the precise requirements made on the local realist model, this can imply (a) no violation, (b) smaller violation than usual, or (c) full violation of the appropriate statistical bound. Alternatives include (a) using only the measurement outcomes as EPR elements of reality, (b) using the emission time as EPR element of reality, (c) using path realism, or (d) using a modified setup. This paper discusses the nature of these alternatives and how to choose between them. The subtleties of this discussion needs to be taken into account when designing and setting up experiments intended to test local realism. Furthermore, these considerations are also important for quantum communication, for example in Bell-inequality-based quantum cryptography, especially when aiming for device independence.

    Ort, förlag, år, upplaga, sidor
    IOP Publishing: Hybrid Open Access, 2014
    Nyckelord
    bell inequalities; energy-time entanglement; elements of reality
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-112643 (URN)10.1088/1751-8113/47/42/424032 (DOI)000344222200033 ()
    Tillgänglig från: 2014-12-05 Skapad: 2014-12-05 Senast uppdaterad: 2017-12-05
    2. Hacking the Bell test using classical light in energy-time entanglement–based quantum key distribution
    Öppna denna publikation i ny flik eller fönster >>Hacking the Bell test using classical light in energy-time entanglement–based quantum key distribution
    Visa övriga...
    2015 (Engelska)Ingår i: Science Advances, ISSN 2375-2548, Vol. 1, nr 11, s. 1-7, artikel-id e1500793Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Photonic systems based on energy-time entanglement have been proposed to test local realism using the Bell inequality. A violation of this inequality normally also certifies security of device-independent quantum key distribution (QKD) so that an attacker cannot eavesdrop or control the system. We show how this security test can be circumvented in energy-time entangled systems when using standard avalanche photodetectors, allowing an attacker to compromise the system without leaving a trace. We reach Bell values up to 3.63 at 97.6% faked detector efficiency using tailored pulses of classical light, which exceeds even the quantum prediction. This is the first demonstration of a violation-faking source that gives both tunable violation and high faked detector efficiency. The implications are severe: the standard Clauser-Horne-Shimony-Holt inequality cannot be used to show device-independent security for energy-time entanglement setups based on Franson’s configuration. However, device-independent security can be reestablished, and we conclude by listing a number of improved tests and experimental setups that would protect against all current and future attacks of this type.

    Ort, förlag, år, upplaga, sidor
    American Association for the Advancement of Science, 2015
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-114210 (URN)10.1126/sciadv.1500793 (DOI)000216604200020 ()
    Anmärkning

    At the time for thesis presentation publication was in status: Manuscript

    At the time for thesis presentation name of publication was: A Classical-Light Attack on Energy-Time Entangled Quantum Key Distribution, and Countermeasures

    Tillgänglig från: 2015-02-13 Skapad: 2015-02-13 Senast uppdaterad: 2018-03-09Bibliografiskt granskad
    3. Tight bounds for the Pearle-Braunstein-Caves chained inequality without the fair-coincidence assumption
    Öppna denna publikation i ny flik eller fönster >>Tight bounds for the Pearle-Braunstein-Caves chained inequality without the fair-coincidence assumption
    2017 (Engelska)Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 96, nr 2, artikel-id 022102Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In any Bell test, loopholes can cause issues in the interpretation of the results, since an apparent violation of the inequality may not correspond to a violation of local realism. An important example is the coincidence-time loophole that arises when detector settings might influence the time when detection will occur. This effect can be observed in many experiments where measurement outcomes are to be compared between remote stations because the interpretation of an ostensible Bell violation strongly depends on the method used to decide coincidence. The coincidence-time loophole has previously been studied for the Clauser-Horne-Shimony-Holt and Clauser-Horne inequalities, but recent experiments have shown the need for a generalization. Here, we study the generalized chained inequality by Pearle, Braunstein, and Caves (PBC) with N amp;gt;= 2 settings per observer. This inequality has applications in, for instance, quantum key distribution where it has been used to reestablish security. In this paper we give the minimum coincidence probability for the PBC inequality for all N amp;gt;= 2 and show that this bound is tight for a violation free of the fair-coincidence assumption. Thus, if an experiment has a coincidence probability exceeding the critical value derived here, the coincidence-time loophole is eliminated.

    Ort, förlag, år, upplaga, sidor
    AMER PHYSICAL SOC, 2017
    Nationell ämneskategori
    Atom- och molekylfysik och optik
    Identifikatorer
    urn:nbn:se:liu:diva-139910 (URN)10.1103/PhysRevA.96.022102 (DOI)000406669400003 ()
    Tillgänglig från: 2017-08-23 Skapad: 2017-08-23 Senast uppdaterad: 2017-11-29
    4. High-visibility time-bin entanglement for testing chained Bell inequalities
    Öppna denna publikation i ny flik eller fönster >>High-visibility time-bin entanglement for testing chained Bell inequalities
    Visa övriga...
    2017 (Engelska)Ingår i: Physical Review A, ISSN 2469-9926, Vol. 95, nr 3, artikel-id 032107Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The violation of Bells inequality requires a well-designed experiment to validate the result. In experiments using energy-time and time-bin entanglement, initially proposed by Franson in 1989, there is an intrinsic loophole due to the high postselection. To obtain a violation in this type of experiment, a chained Bell inequality must be used. However, the local realism bound requires a high visibility in excess of 94.63% in the time-bin entangled state. In this work, we show how such a high visibility can be reached in order to violate a chained Bell inequality with six, eight, and ten terms.

    Ort, förlag, år, upplaga, sidor
    AMER PHYSICAL SOC, 2017
    Nationell ämneskategori
    Annan fysik
    Identifikatorer
    urn:nbn:se:liu:diva-136599 (URN)10.1103/PhysRevA.95.032107 (DOI)000395983300003 ()
    Tillgänglig från: 2017-04-21 Skapad: 2017-04-21 Senast uppdaterad: 2017-10-20
    5. Quantum Bitcoin: An Anonymous, Distributed, and Secure Currency Secured by the No-Cloning Theorem of Quantum Mechanics
    Öppna denna publikation i ny flik eller fönster >>Quantum Bitcoin: An Anonymous, Distributed, and Secure Currency Secured by the No-Cloning Theorem of Quantum Mechanics
    2019 (Engelska)Ingår i: 2019 IEEE International Conference on Blockchain and Cryptocurrency (ICBC), 2019Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    The digital currency Bitcoin has had remarkable growth since it was first proposed in 2008. Its distributed nature allows currency transactions without a central authority by using cryptographic methods and a data structure called the blockchain. Imagine that you could run the Bitcoin protocol on a quantum computer. What advantages can be had over classical Bitcoin? This is the question we answer here by introducing Quantum Bitcoin which, among other features, has immediate local verification of transactions. This is a major improvement over classical Bitcoin since we no longer need the computationally-intensive and time-consuming method of recording all transactions in the blockchain. Quantum Bitcoin is the first distributed quantum currency, and this paper introduces the necessary tools including a novel two-stage quantum mining process. In addition, we have counterfeiting resistance, fully anonymous and free transactions, and a smaller footprint than classical Bitcoin.

    Nyckelord
    Quantum Bitcoin, Bitcoin, Quantum Computing
    Nationell ämneskategori
    Datavetenskap (datalogi)
    Identifikatorer
    urn:nbn:se:liu:diva-129217 (URN)10.1109/BLOC.2019.8751473 (DOI)978-1-7281-1328-9 (ISBN)978-1-7281-1329-6 (ISBN)
    Konferens
    1st IEEE International Conference on Blockchain and Cryptocurrency (IEEE ICBC)
    Tillgänglig från: 2016-06-13 Skapad: 2016-06-13 Senast uppdaterad: 2019-11-05Bibliografiskt granskad
    6. Comment on "Franson Interference Generated by a Two-Level System"
    Öppna denna publikation i ny flik eller fönster >>Comment on "Franson Interference Generated by a Two-Level System"
    2017 (Engelska)Övrigt (Övrigt vetenskapligt)
    Abstract [en]

    In a recent Letter [Phys. Rev. Lett. 118, 030501 (2017)], Peiris, Konthasinghe, and Muller report a Franson interferometry experiment using pairs of photons generated from a two-level semiconductor quantum dot. The authors report a visibility of 66% and claim that this visibility “goes beyond the classical limit of 50% and approaches the limit of violation of Bell’s inequalities (70.7%).” We explain why we do not agree with this last statement and how to fix the problem.

    Ort, förlag, år, sidor
    Ithaca, New York, USA: Cornell University Press, 2017. s. 1
    Nationell ämneskategori
    Atom- och molekylfysik och optik
    Identifikatorer
    urn:nbn:se:liu:diva-142073 (URN)
    Tillgänglig från: 2017-10-20 Skapad: 2017-10-20 Senast uppdaterad: 2019-08-15
  • 165.
    Johansson, Filip
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system.
    Lindström, Christoffer
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system.
    Inter-Process Communication in a Virtualized Environment2018Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Selecting the correct inter-process communication method isan important aspect of ensuring effective inter-vm and inter-container process communication. We will conduct a study ofIPC methods which might be useful and fits the Qemu/KVMvirtual machine and Docker container environments, and se-lect those that fit our criteria. After implementing our chosenmethods we will benchmark them in a test suite to find theones with highest performance in terms of speed. Our resultsshow that, at the most common message sizes, Unix DomainSockets work best for containers and Transparent Inter Pro-cess Communication has the best performance between vir-tual machines out of the chosen methods.

  • 166.
    Jorswieck, Eduard A.
    et al.
    Dresden Univeristy of Technology.
    Badia, Leonardo
    Università degli Studi di Padova.
    Fahldieck, Torsten
    Bell Labs, Alcatel-Lucent.
    Karipidis, Eleftherios
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Luo, Jian
    Fraunhofer Heinrich Hertz Institute.
    Spectrum sharing improves the network efficiency for cellular operators2014Ingår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 52, nr 3, s. 129-136Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The paper describes the potential gain by spectrum sharing between cellular operators in terms of network efficiency. The focus of the study is on a specific resource sharing scenario: spectrum sharing between two operators in cellular downlink transmission. If frequency bands are allocated dynamically and exclusively to one operator – a case called orthogonal spectrum sharing – significant gains in terms of achievable throughput (spectrum sharing gains between 50% and 100%) and user satisfaction are reported for asymmetric scenarios at link and system level as well as from two hardware demonstrators. Additionally, if frequency bands are allocated simultaneously to two operators – a case called non-orthogonal spectrum sharing – further gains are reported. In order to achieve these, different enablers from hardware technologies and base station capabilities are required. However, we argue that all requirements are fulfilled in 3GPP and newer mobile standards. Therefore, the results and conclusions of this overview paper encourage to seriously consider the inter-operator spectrum sharing technologies.

  • 167.
    Jorswieck, Eduard A.
    et al.
    Technical University of Dresden, Germany .
    Boche, Holger
    University of Berlin, Berlin, Germany.
    Han, Zhu
    University of Houston, USA.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Game Theory in Signal Processing and Communications2009Ingår i: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, artikel-id 128184Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Game theory is a branch of mathematics aimed at the modeling and understanding of resource conflict problems. Essentially, the theory splits into two branches: noncooperative and cooperative game theory. The distinction between the two is whether or not the players in the game can make joint decisions regarding the choice of strategy. Noncooperative game theory is closely connected to minimax optimization and typically results in the study of various equilibria, most notably the Nash equilibrium. Cooperative game theory examines how strictly rational (selfish) actors can benefit from voluntary cooperation by reaching bargaining agreements. Another distinction is between static and dynamic game theory, where the latter can be viewed as a combination of game theory and optimal control. In general, the theory provides a structured approach to many important problems arising in signal processing and communications, notably resource allocation and robust transceiver optimization. Recent applications also occur in other emerging fields, such as cognitive radio, spectrum sharing, and in multihop-sensor and adhoc networks.

  • 168.
    Joshi, Raoul
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Sundström, Per
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    WCDMA Cell Load Control in a High-speed Train Scenario: Development of Proactive Load Control Strategies2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Load control design is one of the major cornerstones of radio resource management in today's UMTS networks. A WCDMA cell's ability to utilize available spectrum efficiently, maintain system stability and deliver minimum quality of service (QoS) requirements to in-cell users builds on the algorithms employed to manage the load. Admission control (AC) and congestion control (CC) are the two foremost techniques used for regulating the load, and differing environments will place varying requirements on the AC and CC schemes to optimize the QoS for the entire radio network. This thesis studies a real-life situation where cells are put under strenuous conditions, investigates the degrading effects a high-speed train has on the cell's ability to maintain acceptable levels of QoS, and proposes methods for mitigating these effects.

    The scenario is studied with regard to voice traffic where the limiting radio resource is downlink power. CC schemes that take levels of fairness into account between on-board train users and outdoor users are proposed and evaluated through simulation. Methods to anticipatorily adapt radio resource management (RRM) in a cell to prepare for a train is proposed and evaluated through simulation. A method to detect a high-speed train in a cell, and the users on it, is outlined and motivated but not simulated.

    Simulation results are promising but not conclusive. The suggested CC schemes show a surprising tendency towards an increase in congestion avoidance performance. Proactive RRM shows a significant increase in QoS for on-board users. No negative effects to users in the macro environment is noticed, with regard to the studied metrics.

  • 169.
    Jönsson, Oscar
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska högskolan.
    An explorative study of the technology transfer coach as a preliminary for the design of a computer aid2014Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The university technology transfer coach has an important role in supporting the commercialization of research results. This thesis has studied the technology transfer coach and their needs in the coaching process. The goal has been to investigate information needs of the technology transfer coach as a preliminary for the design of computer aids.Using a grounded theory approach, we interviewed 17 coaches working in the Swedish technology transfer environment. Extracted quotes from interviews were openly coded and categorized. The analysis show three main problem areas related to the information needs of the technology transfer coach; awareness, communication, and resources. Moreover, 20 features for future computer aids were extracted from the interview data and scenarios and personas where developed to exemplify the future use of computer aids.We conclude that there is a need for computer support in the coaching process. Such systems should aid the coach in; awareness, aiding the coach to focus on meetings; communication, aid the coach to transfer commercialisation knowledge; and resources, aid the coach in accessing and delivering of resources to the coachee. However, it is imperative that the computer aids do not interfere with the coach current process; and that the computer aid is not seen as the sole solution.

  • 170.
    Jörgensen, Eskil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem.
    Cell Acquisition and Synchronization for Unlicensed NB-IoT2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Narrowband Internet-of-Things (NB-IoT) är en ny trådlös teknik som är designad för att hantera mobilnät med vidsträckt täckning för ett massivt antal mycket billiga och strömsnåla användarenheter. Studier har inletts för att operera NB-IoT i olicensierade frekvensband, varav några kräver att frekvenshoppande spridningsspektrum, med kort uppehållstid per kanal, används. För att en användarenhet ska kunna ansluta till en basstation måste den slutföra synkronisingsfasen inom uppehållstiden, så att basstationens hoppmönster kan avkodas. På grund utav den stora signalförsvagningen, den smala bandbredden och användarenhetens egenskaper är det en stor utmaning att förkorta synkroniseringstiden. Detta examensarbete studerar olika metoder för att förkorta synkroniseringstiden i NB-IoT utan att öka kraven på användarenheten. Arbetet visar att artificiell snabb-fädning kan kombineras med tätare referenssignalering för att uppnå förbättringar i synkroniseringsprocessen som är tillräckliga för att möjliggöra operation av NB-IoT i olicensierade frekvensband.

  • 171.
    Karhu, Jonas
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    3-D Positioning in Large Warehouses using Radio-frequency identification2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In large warehouses, there are a lot of articles that needs do be kept track of. As the number of articles grows larger, the administrative complexity increases. Thus, a solution that automatically keeps track of the position of each article in real-time is of interest. That is, if an item in the warehouse is moved, no manual administration should be needed to know the new position of the item.

    Radio detection and ranging (RADAR) is a ranging technique that doesn’t need to communicate with an object to find the distance to it, instead signals are sent and when they are reflected off the object and returned to the sender, the distance to the object may be calculated. However, you cannot tell two equally shaped objects apart purely based on RADAR techniques. There are many other techniques for ranging, sound navigation and ranging (SONAR) is another example, but they all lack the possibility of detecting the identity of the object.

    So, in order to find a specific item’s position, some kind of  communication with the item is necessary. Radiofrequency identification (RFID) is a neat technology with which this is possible. An RFID reader can send radio signals out in the air, and objects that are in the vicinity of the reader and are tagged with an RFID tag can receive that signal and respond with it’s unique identification number. This way, the RFID reader can identify the RFID tagged object from a distance. There are also a variety of ways to approximate the distance between reader and tag. Unfortunately this is a rather difficult task, especially in indoor  environments.

    There are already some existing products on the market that uses RFID for different kinds of positioning. In this thesis, the theory behind positioning, the fundamentals of RFID and different positioning solutions will be analysed and presented.

    A number of tests were carried out with an RFID system within the ultra-high frequency (UHF) band, which is around 866 MHz. The test system only supported range estimation based on the received signal strength indicator (RSSI) and the test results showed that narrowband RSSI measurements are highly disturbed by multipath propagation which make the overall positioning performance insufficient. Further analysis of time based range estimation techniques, such as time of arrival (TOA), time of flight (TOF) and time difference of arrival (TDOA), revealed that better positioning accuracy is possible, especially if ultra-wide bandwidth (UWB) is used.

  • 172.
    Karipidis, Eleftherios
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten. University of Maryland, MD 20742 USA.
    He, Qing
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Max-Min Power Control in Wireless Networks With Successive Interference Cancelation2015Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 14, nr 11, s. 6269-6282Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider a wireless network comprising a number of cochannel (hence mutually interfering) links. We study the power control problem of maximizing the rate that all links can simultaneously support under a novel setup, where receivers have interference cancelation (IC) capabilities. The problem of allocating the transmitting power is intertwined with determining the links on which receivers can perform IC and the order of cancelations. We provide and prove the theoretical results of the problem complexity and structural properties. For the problem solution, we propose a mixed-integer linear programming framework that enables jointly determining the optimal power and the IC patterns using off-the-shelf algorithms. This allows for the accurate assessment of the potential of IC for power control. Extensive numerical results are presented for performance evaluation, demonstrating the benefit of deploying IC in power control.

  • 173.
    Karlsson, Eric
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Lagerbielke, Alexander
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Demonstrator Development for Phone as a Key Based on Bluetooth Low Energy2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this work a demonstrator for phone as a key has been developed. This demonstrator estimates the position of a mobile device in and around a test vehicle. Trilateration, ROCRSSI and fingerprinting with neural networks have been investigated for the localization of the mobile device. To filter the input data Kalman filter and average mean filter have been investigated. The best performing technique was determined to be the use of neural networks with a Kalman filter. The resulting demonstrator can determine if the mobile device is within the ranges of three predefined zones for the technology and three zones defined in the thesis. The demonstrator can estimate the location of the mobile device in real-time for these zones.

  • 174.
    Karlsson, Marcus
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Aspects of Massive MIMO2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Det ställs hårda krav på nästa generations cellulära trådlösa system: att simultant öka datatakten på kommunikationen och dess tillförlitlighet utan att konsumera mer resurser, oavsett om det spektrum eller energi. Massiv mimo (eng: Multiple-Input Multiple-Output) har visat, både i teori och praktik, att tekniken är redo att tackla utmaningen. Massiv mimo kan betjäna många användare samtidigt, med god service, utan att öka den utstrålade effekten jämfört med nuvarande system. Massiv mimo, där basstationerna är utrustade med hundratals antenner, skiljer sig från dagens system vilket gör att många nya problem dyker upp och nya infallsvinklar på befintliga problem krävs. Denna avhandling analyserar två problem, och hur dessa förändras i ett massiv mimo sammanhang: säkerhet för fysiska lagret och överföring av systeminformation. Särskiljt visas att en störsändare med ett stort antal antenner kan överträffa en traditionell störsändare med en enda antenn. Antalet antenner ger störsändaren möjlighet att hitta strukturer i signaler och utnyttja detta för att förbättra störningens effekt. Det stora antalet antenner visar sig vara användbart även för överföring av systeminformation, där basstationen inte har någon kanalkännedom. Antennerna ger möjligheten att tillämpa spatial kodning (eng: space-time block coding). Vi visar hur överföringen utan kanalkännedom kan göras i massiv mimo genom att använda en fix förkodningsmatris för att reducera antalet pilotsymboler. Samtidigt kodar vi spatiellt över antennerna för att tillhandahålla spatiell diversitet.

  • 175.
    Karlsson, Marcus
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Blind Massive MIMO Base Stations: Downlink Transmission and Jamming2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Massiv MIMO (eng: Multiple-Input--Multiple-Output) är en teknologi inom cellulär kommunikation som förutspås ha en betydande roll i framtida kommunikationssystem på grund av de många fördelar som denna teknologi medför. Massiv MIMO innebär att basstationen har ett stort antal antenner där varje antenn kan styras individuellt. De många antennerna gör att basstationen kan rikta de elektromagnetiska signalerna på ett sådant sätt att de förstärks på positioner där användarna befinner sig men släcks ut i övrigt. Detta i sin tur innebär att flera användare kan betjänas samtidigt, på samma frekvensband utan att de stör varandra. Detta medför att massiv MIMO kan erbjuda en högre datatakt än nutida cellulära kommunikationssystem.

    För att kunna rikta signalerna på ett effektivt sätt måste basstationen känna till kanalen, eller utbredningsmiljön, mellan sig själv och de användare som betjänas. När en användare precis kommer in i systemet vet basstationen inte var användaren befinner sig, men måste likväl tillgodose användaren med information om hur systemet fungerar. Nu måste alltså basstationen kommunicera med användaren, utan möjligheten att kunna rikta signalen på ett effektivt sätt. Det är detta problem som vi i huvudsak studerar i denna avhandling: hur man kan utnyttja de många antennerna på basstationen för att skicka information till användarna utan någon kanalkännedom.

    Vi studerar även hur en gruppantenn med många antenner, baserad på samma teknologi som massiv MIMO, kan användas som en störsändare. Störsändarens mål är att hindra kommunikationen mellan två enheter på ett effektivt sätt. En störsändare med ett stort antal antenner kan, utan någon kännedom av vad de två enheterna skickar, i många fall prestera bättre än en konventionell störsändare på grund av att störsignalen kan riktas mot en specifik enhet.

    Delarbeten
    1. Performance of In-Band Transmission of System Information in Massive MIMO Systems
    Öppna denna publikation i ny flik eller fönster >>Performance of In-Band Transmission of System Information in Massive MIMO Systems
    2018 (Engelska)Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, nr 3, s. 1700-1712Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We consider transmission of system information in massive multiple-input multiple-output (MIMO). This information needs to be reliably delivered to inactive users in the cell without any channel state information at the base station. Downlink transmission entails the use of downlink pilots and a special type of precoding that aims to reduce the dimension of the downlink channel and the pilot overhead, which would otherwise scale with the number of base station antennas. We consider a scenario in which the base station transmits over a small number of coherence intervals, providing little time/frequency diversity. The system information is transmitted with orthogonal space-time block codes to increase reliability and performance is measured using outage rates. Several different codes are compared, both for spatially correlated and uncorrelated channels and for varying amounts of time/frequency diversity. We show that a massive MIMO base station can outperform a single-antenna base station in all considered scenarios.

    Ort, förlag, år, upplaga, sidor
    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018
    Nyckelord
    Fading channels; array signal processing; signal detection; MIMO; 5G mobile communication; narrowband; spatial diversity; space-time codes
    Nationell ämneskategori
    Telekommunikation
    Identifikatorer
    urn:nbn:se:liu:diva-147125 (URN)10.1109/TWC.2017.2784809 (DOI)000427226500021 ()
    Anmärkning

    Funding Agencies|Swedish Research Council; ELLIIT

    Tillgänglig från: 2018-04-20 Skapad: 2018-04-20 Senast uppdaterad: 2019-06-28
    2. Jamming a TDD Point-to-Point Link Using Reciprocity-Based MIMO
    Öppna denna publikation i ny flik eller fönster >>Jamming a TDD Point-to-Point Link Using Reciprocity-Based MIMO
    2017 (Engelska)Ingår i: IEEE Transactions on Information Forensics and Security, ISSN 1556-6013, E-ISSN 1556-6021, Vol. 12, nr 12, s. 2957-2970Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We present a method for jamming a time-division duplex link using a transceiver with a large number of antennas. By utilizing beamforming, a jammer with M antennas can degrade the spectral efficiency of the primary link more than conventional omnidirectional jammers under the same power constraint, or perform equally well with approximately 1/M of the output power. The jammer operates without any prior knowledge of channels to the legitimate transmitters, or the legitimate signals by relying on channel reciprocity.

    Ort, förlag, år, upplaga, sidor
    IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017
    Nyckelord
    Jamming; beamforming; reciprocity; massive MIMO; time-division duplex
    Nationell ämneskategori
    Telekommunikation
    Identifikatorer
    urn:nbn:se:liu:diva-141105 (URN)10.1109/TIFS.2017.2725823 (DOI)000409037000010 ()
    Anmärkning

    Funding Agencies|Swedish Research Council; ELLIIT

    Tillgänglig från: 2017-09-27 Skapad: 2017-09-27 Senast uppdaterad: 2019-06-28
  • 176.
    Karlsson, Marcus
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    On the Operation of Massive MIMO with and without transmitter CSI2014Ingår i: Signal Processing Advances in Wireless Communications (SPAWC), 2014 IEEE 15th International Workshop on, IEEE , 2014, s. 1-5Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper considers the issue of activating inactive terminals by control signaling in the downlink in a massive MIMO system. There are two basic difficulties with this. First, the lack of CSI at the transmitter. Second, the short coherence interval, which limits the number of orthogonal pilots in the case of many antennas. The proposed scheme deals with these issues by repeating the transmission over the antennas. We show that this repetition does not affect the spectral efficiency significantly, while making it possible to estimate the channel in a standard way using MMSE. The paper also sheds some light the uplink-downlink power balance in massive MIMO.

  • 177.
    Karlsson, Mikael
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem.
    Beam-Forming-Aware Link-Adaptation for Differential Beam-Forming in an LTE FDD System2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The ability for base stations to be able to beam-form their signals, directing the signal energy to specific users, is a topic of research that has been heavily studied during the last decades. The beam-forming technique aims to increase the signal-to-interference-and-noise-ratio of the user and, consequently, increase the capacity and coverage of the communication system. One such method is the Differential Beam-Forming technique, that has been developed at Ericsson Research. In this version of beam-forming, the beams can be dynamically sharpened and widened when tracking a specific terminal, to try to optimize the signal energy sent to that terminal.

    Beam-forming, however, makes the link-adaptation algorithm process substantially harder to perform. The reason for this is that the link-adaptation algorithm now has to take into account not only the changing radio environment, but also the changing transmit signal that is being beam-formed. Fortunately, since the beam-formed signal is known at the point of transmission, there should be a potential to utilize this knowledge to make the link-adaptation more efficient.

    This thesis, investigates how the link-adaptation algorithm could be changed to perform better in beam-forming setups, as well as what information from the beam-forming algorithm that could be included and utilized in the link-adaptation algorithm. This is done by designing and investigating three new link-adaptation algorithms, in the context of Differential Beam-Forming in an LTE FDD system. The algorithms that has been designed are both of a beam-forming-aware and beam-forming-unaware character, meaning if the beam-forming information is utilized within the algorithm, or not. These algorithms have been simulated for different base station antenna array-sizes. Unfortunately, due to simulator restrictions, the terminals have been simulated in a stationary environment, which has proven to be a limiting factor for the results. However, the results still show that smarter beam-forming-aware link-adaptation could possibly be used to increase the performance of the link-adaptation when using beam-forming.

  • 178.
    Karlsson, Tom
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Persson, Mike
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Outdoor localization in long range WSN using trilateration2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis report investigates how good position estimations that can be done outdoors with received signal strength indication (RSSI) trilateration for sub 1-GHz radio nodes. A custom network and an empirical distance model have been created as well as a technique for weighting multiple distance estimations, using wrapped normal probability density functions. The developed localization system was tested on an open area of one square kilometer, to estimate a node’s position on various locations. To evaluate the localization system, mean and median error of the estimated positions were calculated.

  • 179.
    Kasebzadeh, Parinaz
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Parameter Estimation for Mobile Positioning Applications2017Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The availability and reliability of mobile positioning algorithms depend on both the quality of measurements and the environmental characteristics. The positioning systems based on global navigation satellite systems (GNSS), for example, have typically a few meters accuracy but are unavailable in signal denied conditions and unreliable in multipath environments. Other radio network based positioning algorithms have the same drawbacks. This thesis considers a couple of cases where these drawbacks can be mitigated by model-based sensor fusion techniques.

    The received signal strength (RSS) is commonly used in cellular radio networks for positioning due to its high availability, but its reliability depends heavily on the environment. We have studied how the directional dependence in the antenna gain in the base stations can be compensated for. We propose a semiempirical model for RSS  measurements, composed of an empirical log-distance model of the RSS decay rate, and a deterministic antenna gain model that accounts for non-uniform base station antenna radiation. Evaluations and comparisons presented in this study demonstrate an improvement in estimation performance of the joint model compared to the propagation model alone.

    Inertial navigation systems (INS ) rely on integrating inertial sensor measurements. INS  as a standalone system is known to have a cubic drift in the position error, and it needs supporting sensor information, for instance, position fixes from GNSS whenever available. For pedestrians, special tricks such as parametric gait models and step detections can be used to limit the drift. In general, the more accurate gait parameters, the better position estimation accuracy. An improved pedestrian dead reckoning (PDR) algorithm is developed that learns gait parameters in time intervals when direct position measurements (such as GNSS positions) are available. We present a multi-rate filtering solution that leads to improved estimates of both gait parameters and position. To further extend the algorithm to more realistic scenarios, a joint classifier of the user’s motion and the device’s carrying mode is developed. Classification of motion mode (walking, running, standing still) and device mode (hand-held, in pocket, in backpack) provides information that can assist in the gait learning process and hence improve the position estimation. The algorithms are applied to collected data and promising results are reported. Furthermore, one of the most extensive datasets for personal navigation systems using both rigid body motion trackers and smartphones is presented, and this dataset has also been made publicly available.

  • 180.
    Kashyap, Salil
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Can wireless power transfer benefit from large transmitter arrays?2015Ingår i: Proceedings of IEEE Wireless Power Transfer Conference (WPTC), Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 1-3Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we illustrate the potential benefits of using large transmitter arrays for wireless power transfer. Specifically, we analyze the probability of outage in energy transfer over fading channels when the base station (BS) with multiple antennas beamforms energy to a wireless sensor node. Our analytical and numerical results show that by using large transmitter arrays, the range of wireless power transfer can be increased while maintaining a target outage probability. We also observe and quantify that by using multi-antenna arrays at the BS, a lower downlink energy is required to get the same outage performance

  • 181.
    Kashyap, Salil
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    On the feasibility of wireless energy transfer using massive antenna arrays in Rician channels2015Ingår i: 16th IEEE International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2015, Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 46-50Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we examine the feasibility of wireless energy transfer (WET) using arrays with multiple antennas. Specifically, we compute the probability of outage in energy transfer over a Rician fading channel when the base station (BS) with multiple antennas transfers energy to a wireless sensor node (WSN). Through our analytical and numerical results, we prove that by deploying more antennas at the BS, the range of WET can be increased while maintaining a target outage probability. We observe that the use of massive antenna arrays at the BS results into huge savings of radiated energy. We show that for typical energy levels used in WET, the outage performance with imperfect channel state information (CSI) is essentially the same as that obtained based on perfect CSI. We also observe that a strong line-of-sight component between the BS and the WSN lowers the probability of outage in energy transfer.

  • 182.
    Kashyap, Salil
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Mollén, Christopher
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Emil, Björnson
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Performance Analysis of (TDD) Massive MIMO with Kalman Channel Prediction2017Ingår i: Acoustics, Speech and Signal Processing (ICASSP), 2017 IEEE International Conference on, 2017, s. 3554-3558Konferensbidrag (Refereegranskat)
    Abstract [en]

    In massive MIMO systems, which rely on uplink pilots to estimate the channel, the time interval between pilot transmissions constrains the length of the downlink.  Since switching between up- and downlink takes time, longer downlink blocks increase the effective spectral efficiency.  We investigate the use of low-complexity channel models and Kalman filters for channel prediction, to allow for longer intervals between the pilots.  Specifically, we quantify how often uplink pilots have to be sent when the downlink rate is allowed to degrade by a certain percentage.  To this end, we consider a time-correlated channel aging model, whose spectrum is rectangular, and use autoregressive moving average (ARMA) processes to approximate the time-variations of such channels.  We show that ARMA-based predictors can increase the interval between pilots and the spectral efficiency in channels with high Doppler spreads.  We also show that Kalman prediction is robust to mismatches in the channel statistics.

  • 183.
    Kaushik, K.
    et al.
    Department of Electrical Engineering, Bharti School of Telecom, Indian Institute of Technology Delhi, New Delhi, India.
    Mishra, Deepak
    Department of Electrical Engineering, Bharti School of Telecom, Indian Institute of Technology Delhi, New Delhi, India.
    De, Swades
    Department of Electrical Engineering, Bharti School of Telecom, Indian Institute of Technology Delhi, New Delhi, India.
    Chowdhury, Kaushik Roy
    Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, USA.
    Heinzelman, Wendi
    Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA.
    Low-cost wake-up receiver for RF energy harvesting wireless sensor networks2016Ingår i: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 16, nr 16, s. 6270-6278Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The existing passive wake-up receivers (WuRxs) are radio frequency identification (RFID) tag based, which incur high cost and complexity. In this paper, we study cost-effective and long-range WuRx solutions for range-based wake-up (RW) as well as directed wake-up (DW). In particular, we consider the case of an RF energy harvesting wireless sensor node and investigate how a low-cost WuRx can be built using an RF energy harvester available at the node. Experimental results show that our developed prototype can achieve a wake-up range of 1.16 m with +13 dBm transmit power. Furthermore, our empirical study shows that at +30 dBm transmit power the wake-up distance of our developed RW module is >9 m. High accuracy of DW is demonstrated by sending a 5-bit ID from a transmitter at a bit rate up to 33.33 kbps. Finally, we present optimized WuRx designs for RW and DW using Agilent advanced design system, which offer up to 5.69 times higher wake-up range for RW and energy savings per bit of about 0.41 mJ and 21.40 nJ, respectively, at the transmitter and the sensor node in DW.

  • 184.
    Kazim, Muhammad Irfan
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska fakulteten.
    Kazim, Muhammad Imran
    Department of Electrical Engineering, Eindhoven University of Technology (TU/e), P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
    Wikner, J. Jacob
    Linköpings universitet, Institutionen för systemteknik, Elektroniska Kretsar och System. Linköpings universitet, Tekniska fakulteten.
    An Efficient Full-Wave Electromagnetic Analysis for Capacitive Body-Coupled Communication2015Ingår i: International Journal of Antennas and Propagation, ISSN 1687-5869, E-ISSN 1687-5877, Vol. 2015, s. 15-, artikel-id 245621Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Measured propagation loss for capacitive body-coupled communication (BCC) channel (1 MHz to 60 MHz) is limitedly available in the literature for distances longer than 50 cm. This is either because of experimental complexity to isolate the earth-ground or design complexity in realizing a reliable communication link to assess the performance limitations of capacitive BCC channel. Therefore, an alternate efficient full-wave electromagnetic (EM) simulation approach is presented to realistically analyze capacitive BCC, that is, the interaction of capacitive coupler, the human body, and the environment all together. The presented simulation approach is first evaluated for numerical/human body variation uncertainties and then validated with measurement results from literature, followed by the analysis of capacitive BCC channel for twenty different scenarios. The simulation results show that the vertical coupler configuration is less susceptible to physiological variations of underlying tissues compared to the horizontal coupler configuration. The propagation loss is less for arm positions when they are not touching the torso region irrespective of the communication distance. The propagation loss has also been explained for complex scenarios formed by the ground-plane and the material structures (metals or dielectrics) with the human body. The estimated propagation loss has been used to investigate the link-budget requirement for designing capacitive BCC system in CMOS sub-micron technologies.

  • 185.
    Khodari, Mohammad
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik.
    Decentralized firmware attestation for in-vehicle networks2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Today's vehicles are controlled by several so called electronic control units (ECUs). ECUs can be seen as small computers that work together in order to perform a common task. They control everything from critical tasks such as engine control to less critical functionality such as window control. The most prominent trend that can be observed today is the development of self-driving functionality. Due to inherent complexity of self-driving functionality, ECUs are becoming more dependent on each other. A fundamental problem in today's vehicles is that there does not exist any efficient way of achieving trust in the vehicle's internal-network. How can ECUs be assured that the output of other ECUs can be trusted? If an ECU produces the wrong output when the vehicle is in autonomous mode it can lead to the vehicle performing unsafe actions and risking the lives of the passengers and driver.

    In this thesis we evaluate different already established firmware attestation solutions for achieving trust in a decentralized network. Furthermore, three new firmware attestation solutions specially tailored for the automotive domain are proposed. We demonstrate that all the found existing solutions have a fundamental flaw, they all have a single point of failure. Meaning that if you eliminate the correct node, the entire attestation process stops functioning. Thus, a new more robust solution specially tailored for the automotive domain needed to be developed. Three different consistency verification mechanisms were designed. One parallel solution, one serial solution and one merkle-tree solution. Two of the three proposed solutions, the parallel solution and serial solution, were implemented and assessed. Two tests were conducted, a detection performance test and a timing performance test.

    By assessing the detection performance test and timing performance test of the serial and parallel solutions, it was concluded that the parallel solution showed a significant improvement in both stability and performance over the serial solution.

  • 186.
    Khosravi Dehkourdi, Tony
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Simulation Platform for Resource Allocation in Multi-Cellular Wireless Networks2012Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The goal of this Master's thesis was to solve resource allocation problems in wireless networks through the implementation of a lightweight simulation platform. The spectrum and power resources of wireless networks have to be efficiently used to accommodate the growing number of wireless terminals and the massive increase of data transferred by their applications. The major problem that needs to be tackled is interference, which significantly limits the performance of wireless systems. In this thesis, the resource allocation of interest was the joint problem of scheduling and power control with Quality of Service (QoS) constraints. The Signal-to-Interference-plus-Noise Ratio (SINR) was used to quantify QoS. This thesis studied the recently proposed mixed-integer linear programming (MILP) formulation of the problem. Due to the scheduling component, the problem is inherently combinatorial and NP-hard, therefore computationally expensive and difficult to solve in tractable time. A simulation platform was implemented in order to automate and facilitate the solving process.As a starting point, wireless channels and channel modeling issues were studied. Then, the platform was implemented to simulate random instances of multi-cellular wireless networks, with several mobile stations per cell, and generate the corresponding channels. Finally, the platform was extended to use the GNU Linear Programming Kit (GLPK) API in order to optimally solve the aforementioned formulated problem for various inputs of generated channels.Tests of the simulation platform were performed to check the consistency of the results. Indeed, the output results satisfied the initial expectations regarding the SINR constraints and the formulation. Moreover, they were produced in reasonable time. An analysis of the output results was presented.This thesis resulted in a configurable and lightweight simulation platform which is able to solve the MILP-formulated resource allocation problem. The simulation platform is basic and does not cover all the aspects of multi-cellular wireless networks and wireless channels. Due to its modularity, it can be extended in a future project.

  • 187.
    Kieu, Le Minh
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Public transportation modeling in urban areas2011Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Public transportation stands a very important role in the modern society. It solves many transportation problems, reduces the negative impacts of motor vehicles to the environment, and brings benefit and mobility to everyone. Public transportation models are used in urban area transit networks in order to predict the future impacts of the traffic policy and changes. Models in public transportation simulation are extensively studied in the literature, but very few have compared all the available models to a traffic data to find which model is the most accurate one in simulating a transit network.

    This study provides an overview of some of the available approaches in public transportation modeling, describes how they work by both theoretical review and examples. On the analysis, the modeling results from each model are compared with the Stockholm traffic data. The Stockholm traffic data of average weighted travel time, travel distance, in-vehicle travel distance and number of transfers are extracted from the RES05/06 survey data. The model which provides modeling outputs with least root mean square error compared to the survey data is found. This study could give an initial suggestion for the same type of transit modeling in choosing the appropriate model and finding the direction for calibrating the parameter settings through our proposed comparison measures. 

  • 188.
    Korzun, Dmitry
    et al.
    Department of Computer Science, Petrozavodsk State University, Petrozavodsk, Russian Federation.
    Kuptsov, Dmitriy
    Helsinki Institute for Information Technology, Helsinki, Finland.
    Gurtov, Andrei
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    A comparative simulation study of deterministic and stochastic strategies for reduction of packet reordering in multipath data streaming2016Ingår i: International journal of simulation. Systems, Science and Technology, ISSN 1473-8031, E-ISSN 1473-804X, Vol. 17, nr 33, s. 10.1-10.8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multipath routing gains clear network performance advantages for data streaming in networked systems with high path diversity. The level of packet reordering, however, becomes higher: distant packets are reordered, the application performance is reduced due to head-of-line blocking at the destination, and a large resequencing buffer is needed for sorting incoming packets. In this paper, we study by simulation the stochastic compensation effect to reduce packet reordering. If a source randomizes packet scheduling into multiple paths of random transmission delays, then these two sides of randomness “quench” each other. We perform comparison experiments to test this hypothesis in various multipath configurations, focusing on deterministic vs. randomized strategies of packet scheduling. The experiments confirm the existence of the stochastic compensation effect and its considerable influence on the application performance. © 2016, UK Simulation Society. All rights reserved.

  • 189.
    Kosta, Antzela
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Analysis of the Age of Information in Status Update Systems2018Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Rapid advances in wireless technology have taken us towards a pervasively connected world in which a vast array of wireless devices, from mobile phones to environmental sensors, seamlessly communicate with each other. In some of these systems the freshness of the transmitted information is of high importance. Characterization of time-critical information can be done through the so called real-time status updates that are messages, in the form of packets, carrying a timestamp of their generation. Status updates track time-varying content that needs to be transmitted from the generation point to a remote destination within a network. To quantify the freshness of information in networked systems a novel metric, different than delay or latency, termed as "age of information" (AoI) has been introduced. In this thesis, we focus on the communication systems' adaptability to meet stringent timeliness constraints.

    In Paper I, we expand the concept of information ageing by introducing the cost of update delay (CoUD) metric to characterize the cost of having stale information at the destination. Furthermore, we introduce the value of information of update (VoIU) metric that captures the degree of importance of the update received at the destination. A theoretical analysis and insights into the relation of cost and value are provided.

    Paper II investigates AoI in relation with throughput in a shared access setup with heterogeneous traffc. More specifically, we consider a shared access system consisting of a primary link and a network of secondary nodes, with multipacket reception (MPR) capabilities. To study the joint throughput-timeliness performance, we formulate two optimization problems considering both objectives and provide guidelines for the design of such a multiple access system fulfilling both timeliness and throughput requirements.

    Finally, in Paper III we investigate the AoI performance in various multiple access (MA) schemes, including scheduling and random access. We present analysis of the AoI with and without packet management at the transmission queue of the source nodes, considering that packet management is the capability to replace unserved packets at the queue whenever newer ones arrive. We incorporate the effect of channel fading and network path diversity in such a system and provide simulation results that illustrate the impact of network operating parameters on the performance of the different access protocols.  

    Delarbeten
    1. Age and Value of Information: Non-linear Age Case
    Öppna denna publikation i ny flik eller fönster >>Age and Value of Information: Non-linear Age Case
    2017 (Engelska)Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    We consider a real-time status update system consisting of a source-destination network. A stochastic process is observed at the source, and samples, so called status updates, are extracted at random time instances, and delivered to the destination. In this paper, we expand the concept of information ageing by introducing the Cost of Update Delay (CoUD) metric to characterize the cost of having stale information at the destination. We introduce the Value of Information of Update (VoIU) metric that captures the reduction of CoUD upon reception of an update. The importance of the VoIU metric lies on its tractability which enables an alternative performance criterion in status update systems.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2017
    Serie
    IEEE International Symposium on Information Theory, ISSN 2157-8117
    Nationell ämneskategori
    Datorteknik
    Identifikatorer
    urn:nbn:se:liu:diva-148170 (URN)10.1109/ISIT.2017.8006543 (DOI)000430345200066 ()978-1-5090-4096-4 (ISBN)
    Konferens
    IEEE International Symposium on Information Theory (ISIT) 2017
    Tillgänglig från: 2018-06-01 Skapad: 2018-06-01 Senast uppdaterad: 2019-07-15
    2. Age of Information and Throughput in a Shared Access Network with Heterogeneous Traffic
    Öppna denna publikation i ny flik eller fönster >>Age of Information and Throughput in a Shared Access Network with Heterogeneous Traffic
    2018 (Engelska)Ingår i: IEEE Global Telecommunications Conference (GLOBECOM), 2018, pp. 1-6., 2018Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    We consider a cognitive shared access scheme consisting of a high priority primary node and a low priority network with N secondary nodes accessing the spectrum. Assuming bursty traffic at the primary node, saturated queues at the secondary nodes, and multipacket reception capabilities at the receivers, we derive analytical expressions of the time average age of information of the primary node and the throughput of the secondary nodes. We formulate two optimization problems, the first aiming to minimize the time average age of information of the primary node subject to an aggregate secondary throughput requirement. The second problem aims to maximize the aggregate secondary throughput of the network subject to a maximum time average staleness constraint. Our results provide guidelines for the design of a multiple access system with multipacket reception capabilities that fulfills both timeliness and throughput requirements.

    Serie
    IEEE Global Communications Conference ; 2018
    Nyckelord
    Throughput, Receivers, Information age, Delays, Aggregates, Queueing analysis
    Nationell ämneskategori
    Elektroteknik och elektronik Telekommunikation
    Identifikatorer
    urn:nbn:se:liu:diva-154649 (URN)10.1109/GLOCOM.2018.8647212 (DOI)000465774300065 ()978-1-5386-4727-1 (ISBN)978-1-5386-4728-8 (ISBN)
    Konferens
    IEEE Global Telecommunications Conference (GLOBECOM)
    Anmärkning

    Funding agencies: European Unions Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant [642743]

    Tillgänglig från: 2019-02-25 Skapad: 2019-02-25 Senast uppdaterad: 2019-06-28
  • 190.
    Kosta, Antzela
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Pappas, Nikolaos
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Angelakis, Vangelis
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Age of Information: A New Concept, Metric, and Tool2017Bok (Refereegranskat)
    Abstract [en]

    In an increasingly networked world in which information is becoming increasingly actual, how can a system know with certainty just how fresh the information on a remote system is? Much work has been done on delay or latency in systems, but only recently has the concept of the freshness of information in or about a system become quantifiable. This is termed the Age of Information.

    Age of Information provides a whole new set of metrics and tools that can be used to characterize the freshness of information in communications, control and, indeed, information systems. In its early development, this monograph provides the reader with an easy-to-read tutorial-like introduction into this novel approach of dealing with information within systems. A critical summary of the work to date details the concept for the reader. A description of the fundamentals of the performance metrics is then presented before showing how the approach can be used as a tool in improving metrics in other contexts.

    The survey and tutorial nature of this monograph will save any researcher or student considerable time in understanding the basics of Age of Information, which is destined to become an important research topic in networked systems.

  • 191.
    Kosta, Antzela
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Pappas, Nikolaos
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Angelakis, Vangelis
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Age of Information: A New Concept, Metric, and Tool2017Ingår i: Foundations and Trends in Networking, ISSN 1554-057X, Vol. 12, nr 3, s. 162-259Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Age of information (AoI) was introduced in the early 2010s as a notion to characterize the freshness of the knowledge a system has about a process observed remotely. AoI was shown to be a fundamentally novel metric of timeliness, significantly different, to existing ones such as delay and latency. The importance of such a tool is paramount, especially in contexts other than transport of information, since communication takes place also to control, or to compute, or to infer, and not just to reproduce messages of a source. This volume comes to present and discuss the first body of works on AoI and discuss future directions that could yield more challenging and interesting research.

  • 192.
    Kosta, Antzela
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Pappas, Nikolaos
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Ephremides, Anthony
    Univ Maryland, MD 20742 USA.
    Angelakis, Vangelis
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Age of Information Performance of Multiaccess Strategies with Packet Management2019Ingår i: Journal of Communications and Networks, ISSN 1229-2370, E-ISSN 1976-5541, Vol. 21, nr 3, s. 244-255Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider a system consisting of N source nodes communicating with a common receiver. Each source node has a buffer of infinite capacity to store incoming bursty traffic in the form of status updates transmitted in packets, which should maintain the status information at the receiver fresh. Packets waiting for transmission can be discarded to avoid wasting network resources for the transmission of stale information. We investigate the age of information (AoI) performance of the system under scheduled and random access. Moreover, we present analysis of the AoI with and without packet management at the transmission queue of the source nodes, where as packet management we consider the capability to replace unserved packets at the queue whenever newer ones arrive. Finally, we provide simulation results that illustrate the impact of the network operating parameters on the age performance of the different access protocols.

  • 193.
    Kountouris, Marios
    et al.
    Huawei Technologies, France.
    Pappas, Nikolaos
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Avranas, Apostolos
    Huawei Technologies, France.
    QoS Provisioning in Large Wireless Networks2018Ingår i: 16th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt): Workshop on Spatial Stochastic Models for Wireless Networks (SpaSWiN), 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Quality of service (QoS) provisioning in next-generation mobile communications systems entails a deep understanding of the delay performance. The delay in wireless networks is strongly affected by the traffic arrival process and the packet service process, which in turn depends on the medium access mechanisms and the signal-to-interference-plus-noise ratio (SINR). In this work, we analyze the delay of large wireless networks, where the sources are distributed as a Poisson point process. We provide analytical expressions for the service process and derive delay violation probability bounds using tools from stochastic network calculus and stochastic geometry. Furthermore, we analyze the delay performance under statistical queueing constraints imposed as limitations on buffer violation probabilities. The impact of QoS requirements, network geometry and spatial density of interferers on the throughput and delay performance is identified. Our results provide useful guidelines for resource allocation and system dimensioning to guarantee stringent delay requirements.

  • 194.
    Kovalev, Anton
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Garrido, Mario
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Implementation approaches for 512-tap 60 GSa/s chromatic dispersion FIR filters2017Ingår i: Conference Record of The Fifty-First Asilomar Conference on Signals, Systems & Computers / [ed] Michael B. Matthews, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 1779-1783Konferensbidrag (Refereegranskat)
    Abstract [en]

    In optical communication the non-ideal properties of the fibers lead to pulse widening from chromatic dispersion. One way to compensate for this is through digital signal processing. In this work, two architectures for compensation are compared. Both are designed for 60 GSa/s and 512 filter taps and implemented in the frequency domain using FFTs. It is shown that the high-speed requirements introduce constraints on possible architectural choices. Furthermore, the theoretical multiplication complexity estimates are not good predictors for the energy consumption. The results show that the implementation with 10% more multiplications per sample has half the power consumption and one third of the area consumption. The best architecture for this specification results in a power consumption of 3.12 W in a 65 nm technology, corresponding to an energy per complex filter tap of 0.10 mW/GHz.

  • 195.
    Krisell, Martin
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska högskolan.
    Elliptic Curve Digital Signatures in RSA Hardware2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En digital signatur är den elektroniska motsvarigheten till en handskriven signatur. Den kan bevisa källa och integritet för valfri data, och är ett verktyg som blir allt viktigare i takt med att mer och mer information hanteras digitalt.

    Digitala signaturer använder sig av två nycklar. Den ena nyckeln är hemlig och tillåter ägaren att signera data, och den andra är offentlig och tillåter vem som helst att verifiera signaturen. Det är, under förutsättning att nycklarna är tillräck- ligt stora och att det valda systemet är säkert, omöjligt att hitta den hemliga nyckeln utifrån den offentliga. Eftersom en signatur endast är giltig för datan som signerades innebär detta också att det är omöjligt att förfalska en digital signatur.

    Den mest välanvända konstruktionen för att skapa digitala signaturer idag är RSA, som baseras på det svåra matematiska problemet att faktorisera heltal. Det finns dock andra matematiska problem som anses vara ännu svårare, vilket i praktiken innebär att nycklarna kan göras kortare, vilket i sin tur leder till att mindre minne behövs och att beräkningarna går snabbare. Ett sådant alternativ är att använda elliptiska kurvor.

    Det underliggande matematiska problemet för kryptering baserad på elliptiska kurvor skiljer sig från det som RSA bygger på, men de har en viss struktur gemensam. Syftet med detta examensarbete var att utvärdera hur elliptiska kurvor presterar jämfört med RSA, på ett system som är designat för att effektivt utföra RSA.

    De funna resultaten är att metoden med elliptiska kurvor ger stora fördelar, även om man nyttjar hårdvara avsedd för RSA, och att dessa fördelar ökar mångfaldigt om speciell hårdvara används. För några användarfall av digitala signaturer kan, under några år framöver, RSA fortfarande vara fördelaktigt om man bara tittar på hastigheten. För de flesta fall vinner dock elliptiska kurvor, och kommer troligen vara dominant inom kort. 

  • 196.
    Krishnamoorthi, Vengatanathan
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Carlsson, Niklas
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Halepovic, Emir
    ATandT Labs Res, NJ USA.
    Slow but Steady: Cap-based Client-Network Interaction for Improved Streaming Experience2018Ingår i: 2018 IEEE/ACM 26TH INTERNATIONAL SYMPOSIUM ON QUALITY OF SERVICE (IWQOS), IEEE , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Due to widespread popularity of streaming services, many streaming clients typically compete over bottleneck links for their own bandwidth share. However, in such environments, the rate adaptation algorithms used by modern streaming clients often result in instability and unfairness, which negatively affects the playback experience. In addition, mobile clients often waste bandwidth by trying to stream excessively high video bitrates. We present and evaluate a cap-based framework in which the network and clients cooperate to improve the overall Quality of Experience (QoE). First, to motivate the framework, we conduct a comprehensive study using the lab setup showing that a fixed rate cap comes with both benefits (e.g., data savings, improved stability and fairness) and drawbacks (e.g., higher startup times and slower recovery after stalls). To address the drawbacks while keeping the benefits, we then introduce and evaluate a framework that includes (i) buffer-aware rate caps in which the network temporarily boosts the rate cap of clients during video startup and under low buffer conditions, and (ii) boost-aware client-side adaptation algorithms that optimize the bitrate selection during the boost periods. Combined with information sharing between the network and clients, these mechanisms are shown to improve QoE, while reducing wasted bandwidth.

  • 197.
    Kronstrand, Alexander
    et al.
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska fakulteten.
    Holmqvist, Andreas
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska fakulteten.
    Overlay Network2015Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Nowadays, optical fiber is widely used in several areas, especially in communication networking. The main reason is that optical fiber has low attenuation and high bandwidth. However, the switching functionality is performed in the electrical domain (inside the router), thus we have transmission delays in the network lanes. In this study we explore the possibility of developing a hardware “plug-in” that can be connected in parallel with routers of the network enabling the router with “plug-in” to let it bypass time-critical traffic. We researched different switching techniques for optical fibers and realized it would be an expensive endeavor to create one for a large number of wavelength/connections, thus, we scaled it down to prove the concept “plug-in” where we use fiber optical switches and Mux/Demuxes for our design.

    With our chosen optical components, we were able to bypass the routers (layer 3 switches) in our test environment and switch between different users to chose which one has the direct link. The conclusion can be drawn that it is possible to create such a “plug-in” which could be used by ISPs, to provide a faster lane to consumers with less modification of existing networks.

  • 198.
    Kumar, Pardeep
    et al.
    UiT Arctic University of Norway, Norway.
    Gurtov, Andrei
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten. ITMO University, Russia.
    Iinatti, Jari
    University of Oulu, Finland.
    Sain, Mangal
    Dongseo University, South Korea.
    Ha, Phuong H.
    UiT Arctic University of Norway, Norway.
    Access Control Protocol With Node Privacy in Wireless Sensor Networks2016Ingår i: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 16, nr 22, s. 8142-8150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For preventing malicious nodes joining wireless sensor networks (WSNs), an access control mechanism is necessary for the trustworthy cooperation between the nodes. In addition to access control, recently, privacy has been an important topic regarding how to achieve privacy without disclosing the real identity of communicating entities in the WSNs. Based on elliptic curve cryptography, in this paper, we present an access control protocol with node privacy (called ACP) for the WSN. The proposed scheme not only accomplishes the node authentication but also provides the identity privacy (i.e., source to destination and vice-versa) for the communicating entities. Compared with the current state of the art, the proposed solution can defend actively against attacks. The efficacy and the efficiency of the proposed ACP are confirmed through the test bed analysis and performance evaluations.

  • 199.
    Kumar, Sidharth
    et al.
    IIT Delhi, India.
    De, Swades
    IIT Delhi, India.
    Mishra, Deepak
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    RF Energy Transfer Channel Models for Sustainable IoT2018Ingår i: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 5, nr 4, s. 2817-2828Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Self-sustainability of wireless nodes in Internet-of-Things applications can be realized with the help of controlled radio frequency energy transfer (RF-ET). However, due to significant energy loss in wireless dissipation, there is a need for novel schemes to improve the end-to-end RF-ET efficiency. In this paper, first we propose a new channel model for accurately characterizing the harvested dc power at the receiver. This model incorporates the effects of nonline of sight (NLOS) component along with the other factors, such as radiation pattern of transmit and receive antennas, losses associated with different polarization of transmitting field, and efficiency of power harvester circuit. Accuracy of the model is verified via experimental studies in an anechoic chamber (a controlled environment). Supported by experiments in controlled environment, we also formulate an optimization problem by accounting for the effect of NLOS component to maximize the RF-ET efficiency, which cannot be captured by the Friis formula. To solve this nonconvex problem, we present a computationally efficient golden section-based iterative algorithm. Finally, through extensive RF-ET measurements in different practical field environments we obtain the statistical parameters for Rician fading as well as path loss factor associated with shadow fading model, which also asserts the fact that Rayleigh fading is not well suited for RF-ET due to presence of a strong line of sight component.

  • 200.
    Kumar, Sidharth
    et al.
    Department of Electrical Engineering, Indian Institute of Technology Delhi, New Delhi, India.
    Mishra, Deepak
    Department of Electrical Engineering, Indian Institute of Technology Delhi, New Delhi, India.
    De, Swades
    Department of Electrical Engineering, Indian Institute of Technology Delhi, New Delhi, India.
    An accurate channel model for optimizing effect of non-LOS component in RF energy transfer2017Ingår i: 23rd National Conference on Communications, NCC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 1-6Konferensbidrag (Refereegranskat)
    Abstract [en]

    Self-sustainability of wireless sensor nodes can be realized with the help of controlled radio frequency energy transfer (RF-ET). However due to significant energy loss in wireless dissipation, there is a need for novel schemes to improve the end-To-end RF-ET efficiency. In this work we propose a new channel model for accurately characterizing the harvested DC power at the receiver. This model incorporates the effects of non-line of sight (NLOS) component along with the other factors, such as, polarization of transmitting field, radiation pattern of transmit and receive antennas, polarization loss factor, and efficiency of power harvester circuit. We have validated accuracy of the proposed model by carrying out experiments in an anechoic chamber. In addition to this characterization, we formulate an optimization problem by accounting for the effect of NLOS component to maximize the RF-ET efficiency. To solve this nonconvex problem, we present a computationally-efficient golden section based iterative algorithm. Finally, via numerical investigation we show that significant efficiency improvement can be achieved with

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