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  • 251.
    Kratz, Henrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik, Ångström Space Technology Centre (ÅSTC).
    Öjefors, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Stenmark, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik, Ångström Space Technology Centre (ÅSTC).
    Micromachined S-band Patch Antenna with Reduced Dielectric Constant2006Inngår i: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 130-131, s. 478-484Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A generic dielectric constant reduction method for silicon substrates is presented in detail along with a process description to produce variable dielectric layers for planar antennas. Virtually any dielectric constant below the value for solid silicon 11.9 can be produced down to the limit of structural durability. A first-order volumetric average yields a dielectric constant of 3.8 for the following bonded micromachined silicon substrates; small honeycomb cells with wall thickness of 16 μm and inner wall length of 87 μm are etched using deep reactive ion etch (DRIE) to 475 μm depth in each of two 525 μm 4 in. high ohmic wafers. These two wafers are bonded together with the etched side of both wafers facing each other. A manufactured coaxial-fed disk-patch S-band antenna illustrates the method to reduce the dielectric constant for a circular zone with a diameter of 50 mm. The antenna is designed for a center frequency of 2.5 GHz based on a lossless substrate with a dielectric constant of 3.8. Adjusting the simulation model to fit the measured values of the antenna indicates a dielectric constant of 2.2, a dielectric loss tangent of 0.002, a bulk conductivity loss of 0.006 S/m, and a resonance frequency of 3.2 GHz. A low frequency analysis in the interval 200–500 MHz with a lumped element model and a low frequency formula for the capacitance between the patch and ground plane indicates a dielectric constant in the order of 2.7–2.8. Based on measurements in an SEM, a corrected average dielectric constant is found to be 2.9. This correction is due to thinner walls than expected in the manufactured honeycomb structure. Antenna lobe characteristics have been measured with a half-power beamwidth of ∼76° in both the E-plane and H-plane at 3.2 GHz.

  • 252.
    Kratz, Henrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Öjefors, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Thorslund, Robert
    Köhler, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signalbehandling.
    Stenmark, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Micromachined Ka-band Microsystem for Agile High Speed Telemetry2006Inngår i: International Journal of Satellite Communications and NetworkingArtikkel i tidsskrift (Fagfellevurdert)
  • 253. Kung, Enoch
    et al.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Shi, L
    The performance and limitations of e-stealthy attacks on higher order systems2017Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 62, nr 2, s. 941-947Artikkel i tidsskrift (Fagfellevurdert)
  • 254.
    Kung, Enoch
    et al.
    Hong Kong Univ Sci & Technol, Elect & Comp Engn, Kowloon, Hong Kong, Peoples R China..
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Shi, Ling
    Hong Kong Univ Sci & Technol, Elect & Comp Engn, Kowloon, Hong Kong, Peoples R China..
    Optimal Stealthy Attack under KL Divergence and Countermeasure with Randomized Threshold2017Inngår i: IFAC-PapersOnLine, Elsevier, 2017, Vol. 50, nr 1, s. 9496-9501Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In a cyber-physical system, there are potential sources of malicious attacks that can damage the estimation quality in an underlying network control system. The attacker aims to maximize these damages while the estimator attempts to minimize them. In this paper we define an attack's stealth based on the KL divergence and obtain an optimal attack. Furthermore, we suggest one method in which the estimator may limit the damage to the system while imposing on any attack a probability for it to be non-stealthy. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 255.
    Kung, Enoch
    et al.
    Hong Kong Univ Sci & Technol, Dept Elect & Comp Engn, Kowloon, Hong Kong, Peoples R China.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Shi, Ling
    Hong Kong Univ Sci & Technol, Dept Elect & Comp Engn, Kowloon, Hong Kong, Peoples R China.
    The performance and limitations of ε-stealthy attacks on higher order systems2017Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 62, nr 2, s. 941-947Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In a cyber-physical system, security problems are of vital importance as the failure of such system can have catastrophic effects. Detection methods can be employed to sense the existence of an attack. In a previous study of an attack on the controller while avoiding detection in scalar systems under a certain control assumption, the notion of epsilon-stealthiness was introduced and the strength of epsilon-stealthy attacks was fully characterized. We generalize to the vector system and prove the cases in which we show that the limitations of epsilon-stealthy attack do not extend, in the sense that epsilon-stealthy can inflict damage of arbitrary magnitude to a vector system.

  • 256.
    Kurup, D. G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Rydberg, A.
    Ampligying active reflect-antenna using a microstrip-T coupled patch - Design and Measurement2003Inngår i: IEEE Transactions on Microwave Theory and Techniques, ISSN 0018-9480, Vol. 51, nr 8, s. 1960-65Artikkel i tidsskrift (Fagfellevurdert)
  • 257.
    Kurup, D. G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Rydberg, A.
    Design of microwave amplifier using nonresonant slot matching2000Inngår i: Electronics Letters, ISSN 0013-5194, Vol. 36, nr 7, s. 602-03Artikkel i tidsskrift (Fagfellevurdert)
  • 258.
    Kurup, D. G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Rydberg, A.
    Dielectric Connectors for multilayered RF integration1999Inngår i: Microwave and Optical Technology Letters, ISSN 0895-2477, Vol. 23, nr 11, s. 230-33Artikkel i tidsskrift (Fagfellevurdert)
  • 259.
    Kurup, D. G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Rydberg, A.
    Himdi, M.
    Compact microstrip-T coupled patch antenna for dual polarisation and active-antenna applications2002Inngår i: Electronics Letters, ISSN 0013-5194, Vol. 38, nr 21, s. 1240-41Artikkel i tidsskrift (Fagfellevurdert)
  • 260.
    Kurup, D. G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Rydberg, A.
    Himdi, M.
    Design of an unequally spaced reflect-arry2003Inngår i: IEEE Antennas and wireless propagation letters, ISSN 1536-1225, Vol. 2, nr 1, s. 33-35Artikkel i tidsskrift (Fagfellevurdert)
  • 261.
    Kurup, D. G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Rydberg, A.
    Himdi, M.
    Transmission line model for field distribution in microstripline fed H-slots2001Inngår i: Electronics Letters, ISSN 0013-5194, Vol. 37, nr 14, s. 873-74Artikkel i tidsskrift (Fagfellevurdert)
  • 262.
    Kurup, D. G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Rydberg, A.
    Öjefors, E.
    Design of millimeter wave micromachined antennas for WLAN applications using a computationally efficient method2001Inngår i: Proceedings of the European Microwave Conference, LondonArtikkel i tidsskrift (Fagfellevurdert)
  • 263.
    Kurup, Danesh E
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Himdi, M
    Synthesis of uniform amplitude unequally spaced antenna arrays using the differential evolution algorithm2003Inngår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 51, nr 9, s. 2210-2217Artikkel i tidsskrift (Fagfellevurdert)
  • 264.
    Kurup, Dhanesh G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Active and Passive Unequally Spaced Reflect-Arrays and Elements of RF Integration Techniques2003Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Using an array synthesis tool based on a modified differential evolution algorithm, it is shown that the position-phase synthesis exhibits improved pattern characteristics compared to both the phase only and position only synthesis of uniform amplitude antenna arrays. The design of an unequally spaced planar reflect-array and an active power combining reflect-array are presented. The unit cell of the active reflect-array consists of an amplifying active reflect-antenna designed using a novel dual polarized microstrip-T coupled patch antenna. Two modelling approaches are proposed for the active reflect-antenna and the modelling methods are compared with the experiments.

    A computationally efficient analysis of an H-slot in the ground plane of a microstripline is carried out using a transmission line model. To improve the accuracy in the resonant region of the H-slot and retaining the computational efficiency, an artificial neural network is combined with an efficient spectral domain method. An efficient analysis tool for a silicon micromachined H-slot coupled antenna is developed by combining the transmission line models of the H-slot and an aperture coupled antenna. The experimental results are compared with the theory showing good agreement.

    The analysis and design of a microwave amplifier based on non-resonant slot matching is carried out. It is seen that the designed slot matched amplifier has decreased layout size, improved gain and noise figure characteristics compared to a stub matched amplifier. An efficient method for the analysis of non-resonant slots is compared with other approaches showing good agreement. This points to the fact that non-resonant slot matched circuits can be designed with the same speed and efficiency as we design the traditional stub based matching circuits.

    To address the problem of bandwidth and performance of reflect-arrays we propose a dielectric resonator antenna with slotline stubs. As a preliminary step we design a dielectric resonator antenna with slotline feed and the experimental results are compared with those of a commercial CAD tool. Design and analysis of 3D interconnects based on non-radiative dielectric waveguides is carried out. At millimeterwave, these interconnects are useful for hybrid and multilayer integration techniques.

    Delarbeid
    1. Compact microstrip-T coupled patch antenna for dual polarisation and active-antenna applications
    Åpne denne publikasjonen i ny fane eller vindu >>Compact microstrip-T coupled patch antenna for dual polarisation and active-antenna applications
    2002 Inngår i: Electronics Letters, ISSN 0013-5194, Vol. 38, nr 21, s. 1240-41Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-90647 (URN)
    Tilgjengelig fra: 2003-09-05 Laget: 2003-09-05bibliografisk kontrollert
    2. Transmission line model for field distribution in microstripline fed H-slots
    Åpne denne publikasjonen i ny fane eller vindu >>Transmission line model for field distribution in microstripline fed H-slots
    2001 Inngår i: Electronics Letters, ISSN 0013-5194, Vol. 37, nr 14, s. 873-74Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-90648 (URN)
    Tilgjengelig fra: 2003-09-05 Laget: 2003-09-05bibliografisk kontrollert
    3. Design of microwave amplifier using nonresonant slot matching
    Åpne denne publikasjonen i ny fane eller vindu >>Design of microwave amplifier using nonresonant slot matching
    2000 Inngår i: Electronics Letters, ISSN 0013-5194, Vol. 36, nr 7, s. 602-03Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-90649 (URN)
    Tilgjengelig fra: 2003-09-05 Laget: 2003-09-05bibliografisk kontrollert
    4. Design of an unequally spaced reflect-arry
    Åpne denne publikasjonen i ny fane eller vindu >>Design of an unequally spaced reflect-arry
    2003 Inngår i: IEEE Antennas and wireless propagation letters, ISSN 1536-1225, Vol. 2, nr 1, s. 33-35Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-90650 (URN)
    Tilgjengelig fra: 2003-09-05 Laget: 2003-09-05bibliografisk kontrollert
    5. Dielectric Connectors for multilayered RF integration
    Åpne denne publikasjonen i ny fane eller vindu >>Dielectric Connectors for multilayered RF integration
    1999 Inngår i: Microwave and Optical Technology Letters, ISSN 0895-2477, Vol. 23, nr 11, s. 230-33Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-90651 (URN)
    Tilgjengelig fra: 2003-09-05 Laget: 2003-09-05bibliografisk kontrollert
    6. Synthesis of uniform amplitude unequally spaced antenna arrays using differential evolution algorithm
    Åpne denne publikasjonen i ny fane eller vindu >>Synthesis of uniform amplitude unequally spaced antenna arrays using differential evolution algorithm
    2003 (engelsk)Inngår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 51, nr 9, s. 2210-2217Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A computationally efficient global optimizationmethod, the differential evolution algorithm (DEA), is proposedfor the synthesis of uniform amplitude arrays of two classes,i.e., unequally spaced arrays with equal phases and unequalphases. Phase-only synthesis and the synthesis of uniformly exitedunequally spaced arrays (position only synthesis) are comparedand it is seen that, by using the unequal spacing, the number ofarray elements can be significantly reduced for attaining reducedsidelobe levels. From the DEA-based synthesis of unequallyspaced arrays with uniform amplitudes and unequal phases, itis found that a tradeoff exists between the size of the unequallyspaced arrays and the range of phases for the same radiationcharacteristics. The proposed synthesis technique using uniformamplitudes, unequal spacing, and unequal phases (position-phasesynthesis) not only decreases the size of the array for the samesidelobe level compared to both the phase-only synthesis andposition-only synthesis but also retains their advantages.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-90652 (URN)10.1109/TAP.2003.816361 (DOI)
    Tilgjengelig fra: 2003-09-05 Laget: 2003-09-05 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    7. Ampligying active reflect-antenna using a microstrip-T coupled patch - Design and Measurement
    Åpne denne publikasjonen i ny fane eller vindu >>Ampligying active reflect-antenna using a microstrip-T coupled patch - Design and Measurement
    2003 Inngår i: IEEE Transactions on Microwave Theory and Techniques, ISSN 0018-9480, Vol. 51, nr 8, s. 1960-65Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-90653 (URN)
    Tilgjengelig fra: 2003-09-05 Laget: 2003-09-05bibliografisk kontrollert
    8. Design of millimeter wave micromachined antennas for WLAN applications using a computationally efficient method
    Åpne denne publikasjonen i ny fane eller vindu >>Design of millimeter wave micromachined antennas for WLAN applications using a computationally efficient method
    2001 Inngår i: Proceedings of the European Microwave Conference, LondonArtikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-90654 (URN)
    Tilgjengelig fra: 2003-09-05 Laget: 2003-09-05bibliografisk kontrollert
  • 265.
    Kurup, Dhanesh G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Himdi, M.
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Synthesis of uniform amplitude unequally spaced antenna arrays using differential evolution algorithm2003Inngår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 51, nr 9, s. 2210-2217Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A computationally efficient global optimizationmethod, the differential evolution algorithm (DEA), is proposedfor the synthesis of uniform amplitude arrays of two classes,i.e., unequally spaced arrays with equal phases and unequalphases. Phase-only synthesis and the synthesis of uniformly exitedunequally spaced arrays (position only synthesis) are comparedand it is seen that, by using the unequal spacing, the number ofarray elements can be significantly reduced for attaining reducedsidelobe levels. From the DEA-based synthesis of unequallyspaced arrays with uniform amplitudes and unequal phases, itis found that a tradeoff exists between the size of the unequallyspaced arrays and the range of phases for the same radiationcharacteristics. The proposed synthesis technique using uniformamplitudes, unequal spacing, and unequal phases (position-phasesynthesis) not only decreases the size of the array for the samesidelobe level compared to both the phase-only synthesis andposition-only synthesis but also retains their advantages.

  • 266.
    Langelaar, Johannes
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Strömme Mattsson, Adam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Natvig, Filip
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Development of real time audio equalizer application using MATLAB App Designer2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This paper outlines the design of a high-precision graphic audio equalizer with digital filters in parallel, along with its implementation in MATLAB App Designer. The equalizer is comprised of 31 bands separated with a one-third octave frequency ratio, and its frequency response is controlled by 63 filters. Furthermore, the application can process audio signals, in real time, recorded by microphone and from audio files. While processing, it displays an FFT plot of the output sound, also in real time, equipped with a knob by which the refreshing pace can be adjusted. The actual frequency response proved to match the desired one accurately, but the matching is computationally demanding for the computer. An even higher accuracy would entail a computational complexity beyond the power of ordinary computers, and was thus concluded to be inappropriate. As a result, the final application manages to provide most laptops with both high precision and proper functionality.

  • 267.
    Larsson, Bertil
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Tidssynkroniserade mätningar i vattenkraftstationer2010Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Vattenfall and Svenska Kraftnät perform start-up tests, where hydropower generators are used to power up the electrical grid in case of a blackout. To monitor the electrical grid, Phasor Measurement Units (PMU) are used. Each PMU is individually equipped with a GPS-receiver to precisely timestamp the data relative to the official time UTC. During the test, it is also of interest to timestamp the measurement signals from individual hydropower generators to later compare with PMU-data, and thus study the power grids impact on the generator.

     

    The aim is to work out an appropriate method to make these measurements and to build a data acquisition system, capable of timestamp data relative to UTC, from a generator in one of Vattenfalls hydroelectric power stations. The problem is that the generator is located in an underground station which hampers the reception of GPS-signals and wiring should be avoided if possible.

     

    Time synchronization has been solved by using Vattenfalls network, which is synchronized by the network protocol NTP. The network includes the concerned hydropower stations and thus can wiring from the surface be avoided. The maximum error for the server in the specific hydroelectric power station is bounded within [-4.62, 3.18] ms relative to UTC. The conclusion is that Vattenfalls NTP-network meets the requirements to distribute time. A platform from National Instruments, programmed with the graphical language LabVIEW, has been used for data acquisition. The platform is programmed to synchronize its internal clock to a NTP-server, timestamp the input signals and save the data on the internal hard drive.

  • 268.
    Larsson, Joel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Gimbal stabilizer for cockpit bases of terrain vehicle or combat boat: A proof of concept2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The purpose of this project was to construct a 2-axis stabilized model platform, as a proof of concept, intended to use for a cockpit base of a terrain vehicle or a combat boat. The stabilization of the platform in the roll and pitch axes is realized using a feedback control system that contains a proportional-integral-derivative (PID) controller, two DC motors driving the roll and pitch movements, and a 6-axis inertial measurement unit (IMU) measuring the roll and pitch angles.

    The project started with a study of various stabilized platforms and the theories behind them and a model of the system was created in SimuLink to simulate the system and design the controller. After the simulations where satisfactory a model platform of a scaled-down actual size was constructed. The platform’s frame was printed in a 3D printer. The control system for the platform has been implemented. The PID controller was implemented on the Arduino Mega 2560 development board, and it regulates the pitch and roll movements through two DC motors. The platform’s pitch and roll angles are measured by a 3-axis gyroscope in an IMU sensor (MPU-6050). The measurements are processed by a Kalman filter implemented on the Arduino board to reduce the noise.

    The Simulink simulation provided a functioning control system. However, the prototype of the implemented model platform does not work with god stability as expected. The reason for this result is mostly due to the unsuccessful construction of the platform frame and the bad choice of motors.

  • 269.
    Larsson, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Development of a Digital Universal Filter Bank2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This is a master's thesis project, which is a part of the Master Programme in Electrical Engineering at Uppsala university.

    When developing a product or performing measurements, it is sometimes necessary to remove some content of a signal. This might be due to an interfering source that has to be filtered out, or that only a specific frequency interval is of interest. In such a case, it would be practical if a universal frequency selective filter was available and easy to use. In this thesis, a platform for implementing different frequency selective digital filters is developed. Through a user interface, parameters such as sampling frequency, filter order, type of filter and cutoff frequencies are set by the user. This provides a platform which is easy to configure in order to run one or multiple IIR or FIR filters in various constellations. By combining different filters, a wide variety of frequency responses can be obtained. A prototype is constructed, which allows the user to connect up to two input signals and retrieve up to two output signals. The filter bank is programmed in C and implemented in a 32-bit microcontroller, base on the ARM architecture. To get a reliable prototype, a printed circuit board is designed and manufactured. To protect the electronics from external stress, a cover is designed and 3D-printed.

    The filter design algorithms and the algorithm used when running the filter bank gives satisfying results. The capacity of the filter bank can be increased by refining the filtering algorithm. By improving the hardware, noise generated by the electronics can be decreased. The filter bank has a really good potential to become a very useful tool.

  • 270.
    Larsson Sköld, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Parametrisering av en monofonisk melodi: med analys baserad på cepstrogram2011Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Ett vanligt problem att lösa inom musik är transkribering av musik till noter. En algoritm för att transkribera monofoniska signaler till noter utvecklades.För att extrahera grundtonens läge användes en analys baserat på ett cepstrum. Cepstrumet används ofta vid extrahering av grundtoner hos röster.En träffsäkerhet på 99% för en manlig röstinspelning och 90% för en kvinlig uppnåddes. Resultatet blev noter som sedan kunde redigeras av en användare.

  • 271.
    Le Hoang, Sean Chuong
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Automation of ultrasonic Time-of-Flight technique for saw log classification using signal processing2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The thesis project is aimed to automate ultrasonic Time-of-Flight (ToF) technique for saw log classification using signal processing. The ToF technique works in such a way that ultrasonic tone-burst pulses are sent into a saw log, and then the ToF that the pulses take for the propagation is measured and used to calculate the sound speed and further, the Modulus of Elasticity (MoE). Based on the MoE, the quality of the logs is predicted and presorted before sawing. Development of matched filters is the central task for automating the ToF technique. 

    The whole project was carried out in two different parts: 1) Fundamentals and MATLAB implementation, and 2) Real-time implementation based on digital signal processor.    

    In the first part, fundamentals on the ToF technique and matched filters have been studied, and then MATLAB simulations of matched filters for automating the technique have been made. After this, test measurements have been conducted. The test results are shown to be consistent with the simulation: matched filtering works well for automating the ToF technique.

    In the second part of the report, an embedded algorithm has been developed and implemented on a Digital Signal Processor. The algorithm is the first step in the automation of measurements. Eventually, two test measurements have been performed with the DSP. The results were obtained using both oscilloscope to visualize and MATLAB to plot the obtained debug log, and they have shown that the algorithm works, and can automatically measure the ToF, which is in turn used to calculate the sound speed and MoE.

    The further work on the project that needs to be done, is to applying the developed system to the real situations in sawmills, and improving it according to their requirements.

  • 272.
    Leong, Alex S
    et al.
    Department of Electrical and Electronic Engineering, The University of Melbourne, Australien.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Nair, Girish N
    Department of Electrical and Electronic Engineering, The University of Melbourne, Australien.
    A quantized filtering scheme for multi-sensor linear state estimation with non-detectability at the sensors and fusion center feedback2013Konferansepaper (Fagfellevurdert)
  • 273. Leong, Alex S.
    et al.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Nair, Girish N.
    Quantized Filtering Schemes for Multi-Sensor Linear State Estimation: Stability and Performance Under High Rate Quantization2013Inngår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 61, nr 15, s. 3852-3865Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper we consider state estimation of a discrete time linear system using multiple sensors, where the sensors quantize their individual innovations, which are then combined at the fusion center to form a global state estimate. We prove the stability of the estimation scheme under sufficiently high bit rates. We obtain asymptotic approximations for the error covariance matrix that relates the system parameters and quantization levels used by the different sensors. Numerical results show close agreement with the true error covariance for quantization at high rates. An optimal rate allocation problem amongst the different sensors is also considered.

  • 274. Leong, Alex S
    et al.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Quevedo, Daniel E
    On the optimality of threshold policies in event triggered estimation with packet drops2015Konferansepaper (Fagfellevurdert)
  • 275.
    Leong, Alex S.
    et al.
    Univ Paderborn, Dept Elect Engn EIM E, Paderborn, Germany..
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Quevedo, Daniel E.
    Univ Paderborn, Dept Elect Engn EIM E, Paderborn, Germany..
    Optimal Transmission Policies for Variance Based Event Triggered Estimation With an Energy Harvesting Sensor2016Inngår i: 2016 24Th European Signal Processing Conference (EUSIPCO), 2016, s. 225-229Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper considers a remote state estimation problem where a sensor observes a dynamical process, and transmits local state estimates over an independent and identically distributed (i.i.d.) packet dropping channel to a remote estimator. The sensor is equipped with energy harvesting capabilities. At every discrete time instant, provided there is enough battery energy, the sensor decides whether it should transmit or not, in order to minimize the expected estimation error covariance at the remote estimator. For transmission schedules dependent only on the estimation error covariance at the remote estimator, the energy available at the sensor, and the harvested energy, we establish structural results on the optimal scheduling which show that for a given battery energy level and a given harvested energy, the optimal policy is a threshold policy on the error covariance, i.e. transmit if and only if the error covariance exceeds a certain threshold. Similarly, for a given error covariance and a given harvested energy, the optimal policy is a threshold policy on the battery level. Numerical studies confirm the qualitative behaviour predicted by our structural results.

  • 276.
    Leong, Alex S
    et al.
    Paderborn Univ, Dept Elect Engn EIM E, D-33098 Paderborn, Germany.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Quevedo, Daniel E
    Paderborn Univ, Dept Elect Engn EIM E, D-33098 Paderborn, Germany.
    Sensor scheduling in variance based event triggered estimation with packet drops2017Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 62, nr 4, s. 1880-1895Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper considers a remote state estimation problem with multiple sensors observing a dynamical process, where sensors transmit local state estimates over an independent and identically distributed (i.i.d.) packet dropping channel to a remote estimator. At every discrete time instant, the remote estimator decides whether each sensor should transmit or not, with each sensor transmission incurring a fixed energy cost. The channel is shared such that collisions will occur if more than one sensor transmits at a time. Performance is quantified via an optimization problem that minimizes a convex combination of the expected estimation error covariance at the remote estimator and expected energy usage across the sensors. For transmission schedules dependent only on the estimation error covariance at the remote estimator, this work establishes structural results on the optimal scheduling which show that: 1) for unstable systems, if the error covariance is large then a sensor will always be scheduled to transmit and 2) there is a threshold-type behavior in switching from one sensor transmitting to another. Specializing to the single sensor case, these structural results demonstrate that a threshold policy (i.e., transmit if the error covariance exceeds a certain threshold and don't transmit otherwise) is optimal. We also consider the situation where sensors transmit measurements instead of state estimates, and establish structural results including the optimality of threshold policies for the single sensor, scalar case. These results provide a theoretical justification for the use of such threshold policies in variance based event triggered estimation. Numerical studies confirm the qualitative behavior predicted by our structural results.

  • 277.
    Leong, Alex S
    et al.
    Department of Electical Engineering, Paderborn University, Tyskland.
    Quevedo, Daniel
    Department of Electrical Engineering, Paderborn University, Tyskland.
    Dolz, Daniel
    Procter & Gamble, Germany.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Transmission Scheduling for Remote State Estimation over Packet Dropping Links in the Presence of an Eavesdropper2019Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 64, nr 9, s. 3732-3739Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper studies remote state estimation in the presence of an eavesdropper. A sensor transmits local state estimates over a packet dropping link to a remote estimator, while an eavesdropper can successfully overhear each sensor transmission with a certain probability. The objective is to determine when the sensor should transmit, in order to minimize the estimation error covariance at the remote estimator, while trying to keep the eavesdropper error covariance above a certain level. This is done by solving an optimization problem that minimizes a linear combination of the expected estimation error covariance and the negative of the expected eavesdropper error covariance. Structural results on the optimal transmission policy are derived, and shown to exhibit thresholding behaviour in the estimation error covariances. In the infinite horizon situation, it is shown that with unstable systems one can keep the expected estimation error covariance bounded while the expected eavesdropper error covariance becomes unbounded. An alternative measure of security, constraining the amount of information revealed to the eavesdropper, is also considered, and similar structural results on the optimal transmission policy are derived. In the infinite horizon situation with unstable systems, it is now shown that for any transmission policy which keeps the expected estimation error covariance bounded, the expected amount of information revealed to the eavesdropper is always lower bounded away from zero. An extension of our results to the transmission of measurements is also presented.

  • 278.
    Leong, Alex S
    et al.
    Univ Paderborn, Dept Elect Engn EIM E, D-33098 Paderborn, Germany.
    Quevedo, Daniel E
    Univ Paderborn, Dept Elect Engn EIM E, D-33098 Paderborn, Germany.
    Ahlén, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Johansson, K H
    Royal Inst Technol, ACCESS Linnaeus Ctr, Sch Elect Engn, S-10044 Stockholm, Sweden.
    On network topology reconfiguration for remote state estimation2016Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 61, nr 12, s. 3842-3856Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we investigate network topology reconfiguration in wireless sensor networks for remote state estimation, where sensor observations are transmitted, possibly via intermediate sensors, to a central gateway/estimator. The time-varying wireless network environment is modelled by the notion of a network state process, which is a randomly time-varying semi-Markov chain and determines the packet reception probabilities of links at different times. For each network state, different network configurations can be used, which govern the network topology and routing of packets. The problem addressed is to determine the optimal network configuration to use in each network state, in order to minimize an expected error covariance measure. Computation of the expected error covariance cost function has a complexity of O(2(M Delta max)), where M is the number of sensors and Delta max is the maximum time between transitions of the semi-Markov chain. A sub-optimal method which minimizes the upper bound of the expected error covariance, that can be computed with a reduced complexity of O(2(M)), is proposed, which in many cases gives identical results to the optimal method. Conditions for estimator stability under both the optimal and suboptimal reconfiguration methods are derived using stochastic Lyapunov functions. Numerical results and comparisons with other low complexity approaches demonstrate the performance benefits of our approach.

  • 279.
    Leong, Alex S
    et al.
    Department of Electrical and Electronic Engineering, The University of Melbourne, Parkville, VIC 3052, Australien.
    Quevedo, Daniel E
    School of Electrical Engineering & Computer Science, The University of Newcastle, Newcastle, Australien.
    Ahlén, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Johansson, KH
    KTH, Stockholm.
    Network topology reconfiguration for state estimation over sensor networks with correlated packet drops2014Konferansepaper (Fagfellevurdert)
  • 280.
    Leong, Alex S.
    et al.
    Paderborn Univ, Dept Elect Engn EIM E, Paderborn, Germany..
    Quevedo, Daniel E.
    Paderborn Univ, Dept Elect Engn EIM E, Paderborn, Germany..
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    State Estimation Over Markovian Packet Dropping Links in the Presence of an Eavesdropper2017Inngår i: 2017 IEEE 56Th Annual Conference On Decision And Control (Cdc), IEEE, 2017, s. 6616-6621Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Remote state estimation problems in the presence of an eavesdropper have recently been studied. In this setup, a sensor transmits over a random packet dropping link to a remote estimator, which at the same time can be randomly overheard by an eavesdropper. For i.i.d. packet dropping links to the remote estimator and to the eavesdropper, it has been shown that with unstable systems one can keep the expected estimation error covariance bounded, while the expected eavesdropper error covariance becomes unbounded in the infinite horizon. In this paper we show that the same behaviour can be achieved when transmission of local state estimates occur over a Markovian packet dropping link, and eavesdropping occurs according to another Markovian packet dropping link.

  • 281.
    Leong, Alex S.
    et al.
    Paderborn Univ, Dept Elect Engn EIM E, Paderborn, Germany..
    Quevedo, Daniel E.
    Paderborn Univ, Dept Elect Engn EIM E, Paderborn, Germany..
    Dolz, Daniel
    Procter & Gamble, North Rhine Westphalia, Germany..
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    On Remote State Estimation in the Presence of an Eavesdropper2017Inngår i: IFAC-PapersOnLine, Elsevier, 2017, Vol. 50, nr 1, s. 7339-7344Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper studies a remote state estimation problem in the presence of an eavesdropper. A sensor transmits local state estimates over a packet dropping link to a remote estimator, which at the same time can be overheard by an eavesdropper with a certain probability. The objective is to determine when the sensor should transmit, in order to minimize the estimation error covariance at the remote estimator, while trying to keep the eavesdropper error covariance above a certain level. This is done by solving an optimization problem that minimizes a linear combination of the expected estimation error covariance and the negative of the expected eavesdropper error covariance. Structural results on the optimal transmission policy are derived, and shown to exhibit thresholding behaviour in the estimation error covariances. In the infinite horizon situation, it is shown that with unstable systems one can keep the expected estimation error covariance bounded while the expected eavesdropper error covariance becomes unbounded. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 282.
    Leong, Alex S
    et al.
    Department of Electical Engineering, Paderborn University, Tyskland.
    Quevedo, Daniel E
    Department of Electrical Engineering, Paderborn University, Tyskland.
    Tanaka, Takashi
    Royal Inst Technol, Sch Elect Engn, Dept Automat Control, Stockholm, Sweden.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Ahlén, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Event-Based Transmission Scheduling and LQG Control Over a Packet Dropping Link2017Inngår i: 20th IFAC World Congress / [ed] Denis Dochain, Didier Henrion, Dimitri Peaucelle, Elsevier, 2017, s. 8945-8950Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper studies a joint transmission scheduling and controller design problem, which minimizes a linear combination of the control cost and expected energy usage of the sensor. Assuming that the sensor transmission decisions are event-based and determined using the random estimation error covariance information available to the controller, we show a separation in the design of the transmission scheduler and controller. The optimal controller is given as the solution to an LQG-type problem, while the optimal transmission policy is a threshold policy on the estimation error covariance at the controller.

  • 283. Leong, AS
    et al.
    Quevedo, Daniel E
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Optimal control of energy resources for state estimation over wireless channels2018Inngår i: SpringerBriefs in Control, Automation and Robotics / [ed] Başar, Tamer; Krstic, Miroslav, Springer Publishing Company, 2018Kapittel i bok, del av antologi (Fagfellevurdert)
  • 284.
    Li, Jingya
    et al.
    Dept of Signals and Systems, Chalmers Tekniska Universitet, Göteborg.
    Papadogiannis, Agisilaos
    Dept of Signals and Systems, Chalmers Tekniska Universitet, Göteborg.
    Apelfröjd, Rikke
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Svensson, Tommy
    Dept of Signals and Systems, Chalmers Tekniska Universitet, Göteborg.
    Sternad, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Performance evaluation of coordinated multi-point transmission schemes with predicted CSI2012Inngår i: IEEE Conference on Personal, Indoor and Mobile Radio Communications, PIMRC, Sydney, Australien, 2012, s. 1055-1060Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Coordinated multi-point (CoMP) transmission is considered as an efficient technique to improve cell-edge performance as well as system spectrum efficiency. In CoMP-enabled systems, a cluster of coordinated base stations (BSs) are typically assumed to be connected to a control unit (CU) via backhaul links, and the provided performance gain relies heavily on the quality of the channel state information (CSI) available at the CU side. In this paper, we consider the downlink of a CoMP cluster and compare three different CoMP transmission schemes: zero-forcing coherent joint transmission, non-coherent joint transmission and coordinated scheduling. Moreover, for each of the analyzed schemes, the performance in terms of average sum rate of the CoMP cluster is studied with predicted CSI, considering the effects of the feedback and backhaul latency, as well as the user mobility. Compared to zero-forcing coherent joint transmission, we show that non-coherent joint transmission and coordinated scheduling are more robust to channel uncertainty. In addition, depending on the latency, user mobility and user locations, different schemes would achieve the highest average sum rate performance. Hence, a system could switch between the transmission schemes to improve the sum rate.

  • 285. Li, Y
    et al.
    Zhang, F
    Quevedo, Daniel E
    Department of Electrical Engineering, Paderborn University, Tyskland.
    Lau, V K
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Shi, L
    Power control of an energy harvesting sensor for remote state estimation2017Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 62, nr 1, s. 277-290Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate sensor transmission power control for remote state estimation. Instead of using a conventional sensor, a sensor equipped with an energy harvester which can obtain energy from the external environment is utilized. We formulate power control of the energy harvesting sensor into an infinite time-horizon Markov decision process (MDP). To deal with the computation complexity associated with this multi-dimensional MDP, a continuous-time approach and perturbation analysis are used and a closed-form approximate value function is derived. Based on the approximation, we obtain a closed-form optimal power control solution which has a threshold-based structure. A numerical example is provided to evaluate the estimation performance of the optimal solution compared with other power scheduling schemes.

  • 286.
    Li, Yuzhe
    et al.
    Univ Alberta, Dept Elect & Comp Engn, Edmonton, AB T6G 1H9, Canada.
    Quevedo, Daniel E
    Univ Paderborn, Dept Elect Engn, D-33098 Paderborn, Germany.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Shi, Ling
    Hong Kong Univ Sci & Technol, Dept Elect & Comp Engn, Kowloon, Hong Kong, Peoples R China.
    A game-theoretic approach to fake-acknowledgment attack on cyber-physical systems2017Inngår i: IEEE Transactions on Signal and Information Processing over Networks, E-ISSN 2373-776X, Vol. 3, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A class of malicious attacks against remote state estimation in cyber-physical systems is considered. A sensor adopts an acknowledgement (ACK)-based online power schedule to improve the remote state estimation performance under limited resources. To launch malicious attacks, the attacker can modify the ACKs from the remote estimator and convey fake information to the sensor, thereby misleading the sensor with subsequent performance degradation. One feasible attack pattern is proposed and the corresponding effect on the estimation performance is derived analytically. Due to the ACKs being unreliable, the sensor needs to decide at each instant, whether to trust the ACK information or not and adapt the transmission schedule accordingly. In the meanwhile, there is also a tradeoff for the attacker between attacking and not attacking when the modification of ACKs is costly. To investigate the optimal strategies for both the sensor and the attacker, a game-theoretic framework is built and the equilibrium for both sides is studied.

  • 287.
    Li, Yuzhe
    et al.
    Univ Alberta, Dept Elect & Comp Engn, Edmonton, AB, Canada.
    Quevedo, Daniel E.
    Univ Paderborn, Dept Elect Engn EIM E, Paderborn, Germany.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Shi, Ling
    Hong Kong Univ Sci & Technol, Dept Elect & Comp Engn, Hong Kong, Hong Kong, Peoples R China.
    Fake-acknowledgment attack on ACK-based sensor power schedule for remote state estimation2015Inngår i: 2015 54th IEEE Conference On Decision And Control (CDC), 2015, s. 5795-5800Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider a class of malicious attacks against remote state estimation. A sensor with limited resources adopts an acknowledgement (ACK)-based online power schedule to improve the remote state estimation performance. A malicious attacker can modify the ACKs from the remote estimator and convey fake information to the sensor. When the capability of the attacker is limited, we propose an attack strategy for the attacker and analyze the corresponding effect on the estimation performance. The possible responses of the sensor are studied and a condition for the sensor to discard ACKs and switch from online schedule to offline schedule is provided.

  • 288.
    Li, Yuzhe
    et al.
    Hong Kong Univ Sci & Technol, Hong Kong, Peoples R China.
    Quevedo, Daniel E
    Paderborn Univ, Paderborn, Germany.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Shi, Ling
    Hong Kong Univ Sci & Technol, Hong Kong, Peoples R China.
    SINR-based DoS attack on remote state estimation: A game-theoretic approach2017Inngår i: IEEE Transactions on Control of Network Systems, ISSN 2325-5870, Vol. 4, nr 3, s. 632-642Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider remote state estimation of cyberphysical systems under signal-to-interference-plus-noise ratio-based denial-of-service attacks. A sensor sends its local estimate to a remote estimator through a wireless network that may suffer interference from an attacker. Both the sensor and the attacker have energy constraints. We first study an associated two-player game when multiple power levels are available. Then, we build a Markov game framework to model the interactive decision-making process based on the current state and information collected from previous time steps. To solve the associated optimality (Bellman) equations, a modified Nash Q-learning algorithm is applied to obtain the optimal solutions. Numerical examples and simulations are provided to demonstrate our results.

  • 289.
    Li, Yuzhe
    et al.
    Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowlooon, Hong Kong.
    Quevedo, Daniel E
    School of Electrical Engineering & Computer Science, The University of Newcastle, NSW 2308, Australien.
    Lau, Vincent
    Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowlooon, Hong Kong.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Shi, Ling
    Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowlooon, Hong Kong.
    Transmission power scheduling for energy harvesting sensor in remote state estimation2014Inngår i: Proceedings of the 19th World Congress, 2014, s. 122-127Konferansepaper (Fagfellevurdert)
  • 290. Limmanee, A
    et al.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Nekouei, E
    Optimal power policies and throughput scaling analyses in fading cognitive broadcast channels with primary outage probability constraint2014Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, s. 35-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper focuses on a spectrum-sharing-based fading cognitive radio broadcast channel (BC) with a single-antenna secondary base station (SBS) and M single-antenna secondary receivers (SRs) utilizing the same spectrum band with a delay-sensitive primary user (PU). The service-quality requirement for the primary user is set by an outage probability constraint (POC). We address the optimal power allocation problem for the SBS ergodic sum capacity (ESC) maximization in the secondary BC network subject to POC and a transmit power constraint at SBS specified by either a long-term or a short-term power constraint. The optimality conditions reveal that in each joint channel state, the SBS allocates transmission power to the only one selected SR with the highest value of a certain metric consisting of the ratio of the SR's direct channel power gain and the sum of interference power and noise power at the SR. Then, the secondary network throughput scaling analysis as the number of SRs becomes large, is also investigated, showing that if PU applies a truncated channel inversion (TCI) power policy, the SBS ESC scales like epsilon(p) log(log M) where epsilon(p) is the PU outage probability threshold. To reduce the amount of channel side information (CSI) transferred between the two networks, we propose a suboptimal transmission scheme which requires only 1-bit feedback from the delay-sensitive PR (partial CSI). We show that the new power control policy is asymptotically optimal, i.e. the SBS ESC under this reduced feedback scheme still scales like epsilon(p) log(log M).

  • 291.
    Limmanee, Athipat
    et al.
    Department of Electrical and Electronic Engineering, The University of Melbourne, VIC 3010, Australien.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Ahlén, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Distorsion minimization via multiple sensors under energy harvesting constraints2013Konferansepaper (Fagfellevurdert)
  • 292.
    Limmanee, Athipat
    et al.
    Department of Electrical and Electronic Engineering, The University of Melbourne, Australien.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Evans, Jamie S
    Department of Electrical and Electronic Engineering, The University of Melbourne, Australien.
    Service-outage capacity maximization in cognitive radio for parallel fading channels2013Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 61, nr 2, s. 507-520Artikkel i tidsskrift (Fagfellevurdert)
  • 293.
    Lindberg, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Wideband Active and Passive Antenna Solutions for Handheld Terminals2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis presents solutions and studies related to the design of wideband antennas for wireless handheld terminal applications. A method of electrically shortening the terminal chassis length to obtain resonance at high frequencies has been proposed and evaluated, thereby increasing the antennas impedance bandwidth. No significant effect on the lower frequency band in a dual-band antenna prototype has been observed, making the method suitable for multi-band applications. The chassis has further been utilized as a zero-thickness 0.9 - 2.7 GHz high efficiency antenna by inserting a notch in the chassis center, and a feasibility study for typical phones has been performed. Additionally, the effect of talk position on the chassis wave-mode has been investigated, where the standard equivalent circuit model for terminal antennas has been modified to include the presence of the users head. The model has been used to explain measured and simulated effects concerning frequency detuning, efficiency reduction and bandwidth enhancements when the terminal is placed in talk position.

    The use of a hands-free earpiece cord is currently mandatory for FM radio reception as the cord is utilized as antenna. However, there is currently a market driven demand for removing the cord requirement since many modern phones are equipped with speakers and Bluetooth headsets. In this thesis, an active ferrite loop antenna is proposed as an internal replacement/complement with a performance of -23 dB (G/T degradation) compared to a full-size lossless dipole in urban environments. Also, a modification to the cord is suggested for DVB H reception.

    Complex matching networks have been investigated to increase the bandwidth of dual band PIFA antennas, and a printed dual band dipole has been integrated with a modified Marchand balun for dual resonance at two separate frequency bands, thus covering the commercial cellular bands 824-960 and 1710-2170 MHz with a single antenna.

    Delarbeid
    1. A Bandwidth Enhancement Technique for Mobile Handset Antennas using Wavetraps
    Åpne denne publikasjonen i ny fane eller vindu >>A Bandwidth Enhancement Technique for Mobile Handset Antennas using Wavetraps
    2006 (engelsk)Inngår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 54, nr 8, s. 2226-2233Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A novel technique for enhancing the impedance bandwidth of wireless terminal antennas is presented. By introducing resonant short circuit transmission lines to the long sides of the chassis edges, an effective electrical shortening of the terminal ground plane is achieved. This effect has been used to realize terminal ground planes with resonant lengths at high frequencies, such as GSM 1800/1900.MHz or UNITS 2 GHz, thereby extending the impedance bandwidth. The proposed technique has been validated by simulations and measurements. Three typical applications are presented where the introduction of wavetraps improves the bandwidth and/or in-band performance.

    Emneord
    bandwidth, broadband communication, microstrip antennas, mobile antennas
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-95373 (URN)10.1109/TAP.2006.879211 (DOI)000240116800006 ()
    Tilgjengelig fra: 2007-01-12 Laget: 2007-01-12 Sist oppdatert: 2017-12-14bibliografisk kontrollert
    2. Earpiece cord antenna for DVB-H reception in wireless terminals
    Åpne denne publikasjonen i ny fane eller vindu >>Earpiece cord antenna for DVB-H reception in wireless terminals
    2006 (engelsk)Inngår i: IEE Electronics Letters, Vol. 42, nr 11, s. 3-Artikkel i tidsskrift (Fagfellevurdert) Published
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-95374 (URN)
    Tilgjengelig fra: 2007-01-12 Laget: 2007-01-12