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  • 1.
    Agrawal, Piyush
    et al.
    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.
    Olofsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Gidlund, Mikael
    Long Term Channel Characterization for Energy Efficient Transmission in Industrial Environments2014Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 62, nr 8, s. 3004-3014Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the challenges for a successful use of wireless sensor networks in process industries is to design networks with energy efficient transmission, to increase the lifetime of the deployed network while maintaining the required latency and bit-error rate. The design of such transmission schemes depend on the radio channel characteristics of the region. This paper presents an investigation of the statistical properties of the radio channel in a typical process industry, particularly when the network is meant to be deployed for a long time duration, e. g., days, weeks, and even months. Using 17-20-h-long extensive measurement campaigns in a rolling mill and a paper mill, we highlight the non-stationarity in the environment and quantify the ability of various distributions, given in the literature, to describe the variations on the links. Finally, we analyze the design of an optimal received signal-to-noise ratio (SNR) for the deployed nodes and show that improper selection of the distribution for modeling of the variations in the channel can lead to an overuse of energy by a factor of four or even higher.

  • 2.
    Ahani, Ghafour
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Yuan, Di
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    On optimal proactive and retention-aware caching with user mobility2018Inngår i: 2018 IEEE 88th Vehicular Technology Conference (VTC-Fall), IEEE, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Caching popular contents at edge devices is an effective solution to alleviate the burden of the backhaul networks. Earlier investigations commonly neglected the storage cost in caching. More recently, retention-aware caching, where both the downloading cost and storage cost are accounted for, is attracting attention. Motivated by this, we address proactive and retention-aware caching problem with the presence of user mobility, optimizing the sum of the two types of costs. More precisely, a cost-optimal caching problem for vehicle-to-vehicle networks is formulated with joint consideration of the impact of the number of vehicles, cache size, storage cost, and content request probability. This is a combinatorial optimization problem. However, we derive a stream of analytical results and they together lead to an algorithm that guarantees global optimum with polynomial-time complexity. Numerical results show significant improvements in comparison to popular caching and random caching.

  • 3.
    Al-Husseiny, Zeid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Energy Efficient LTE Site Operation: with Antenna Muting and dynamic Psi-Omni2014Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    To allow access to the network at all times a base station has to continuously stay active. While being active, a base station does not usually transmit data constantly. Typically, the base stations either send out lots of data or barely anything at all, yet, the network is actively drawing power the whole time. Succeeding in lowering the power consumed when the data rate is often so low would therefore lead to great benefits, both economically and environmentally, as well as new prospects of innovation in engineering. The process of how to dynamically change from a capacity optimized mode to an energy optimized mode as well as when to do this change is studied in this thesis for LTE.

    By using methods such as antenna muting and psi-omni coverage, the power consumption can decrease. These solutions however also decreases performance, and has to be activated with great care in mind not to cause any major impact on user performance. The dynamic configuration is dependent on the load of the system, changing to an energy efficient mode when traffic is low and to a capacity optimized mode when the network needs to supply high data rates.

    Simulations show that most energy savings can be found in rural and urban environments. Dynamic antenna muting achieved, summarizing macro environments, 24.9% energy savings with 95.27% downlink data rates compared to the reference case of using sector mode continuously i.e MIMO. In the same environments, dynamic psi-omni coverage together with antenna muting achieved energy savings of 43.8% with 89.3% downlink data rates compared to typical sector mode. Traffic rates are based on future demands in Europe by 2015, assuming that 20% of the subscribers are downloading 900 MB/h and the other 80% subscribers, at 112.5 MB/h. 

  • 4.
    Apelfröjd, Rikke
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Channel Estimation and Prediction for 5G Applications2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Accurate channel state information (CSI) is important for many candidate techniques of future wireless communication systems. However, acquiring CSI can sometimes be difficult, especially if the user equipment is mobile in which case the future channel realisations must be estimated/predicted. In realistic settings the predictability of radio channels is limited due to measurement noise, limited model orders and since the fading statistics must be modelled based on a set of limited and noisy training data.

    In this thesis, the limits of predictability for the radio channel are investigated. Results show that the predictability is limited primarily due to limitations in the training data, while the model order provides a second order limitation effect and the measurement noise comes in as a third order effect.

    Then, a Kalman-based linear filter is studied for potential 5G technologies:

    Coherent coordinated multipoint joint transmission, where channel predictions and the covariance matrix of the prediction error are used to design a robust linear precoder, evaluated in a three base station system. Results show that prediction improves the CSI for the pedestrian users such that system delays of 10 ms are acceptable. The use of the covariance matrix is important for difficult user groups, but of less importance with a simple user grouping system proposed.

    Massive multiple-input multiple-output (MIMO) in frequency division duplex (FDD) systems were a reduced, suboptimal, Kalman filter is suggested to estimate channels based on non-orthogonal pilots. By introducing a fixed grid of beams, the system generates sparsity in the channel vectors seen by each user, which then estimates its most relevant channels based on unique pilot codes for each beam. Results show that there is a 5 dB loss compared to orthogonal pilots.

    Downlink time division duplex (TDD) channels are estimated based on uplink pilots. By using a predictor antenna, which scouts the channel in advance, the desired downlink channel can be estimated using pilot-based estimates of the channels before and after it (in space). Results indicate that, with the help of Kalman smoothing, predictor antennas can enable accurate CSI for TDD downlinks at vehicular velocities of 80 km/h.

    Delarbeid
    1. Kalman predictions for multipoint OFDM downlink channels
    Åpne denne publikasjonen i ny fane eller vindu >>Kalman predictions for multipoint OFDM downlink channels
    2014 (engelsk)Rapport (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Elektroteknik med inriktning mot signalbehandling
    Identifikatorer
    urn:nbn:se:uu:diva-235010 (URN)
    Tilgjengelig fra: 2014-10-28 Laget: 2014-10-28 Sist oppdatert: 2018-03-07
    2. Design and measurement based evaluations of coherent JT CoMP: A study of precoding, user grouping and resource allocation using predicted CSI
    Åpne denne publikasjonen i ny fane eller vindu >>Design and measurement based evaluations of coherent JT CoMP: A study of precoding, user grouping and resource allocation using predicted CSI
    2014 (engelsk)Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499Artikkel i tidsskrift (Fagfellevurdert) Published
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-235014 (URN)DOI:10.1186/1687-1499-2014-100 (DOI)
    Tilgjengelig fra: 2014-10-28 Laget: 2014-10-28 Sist oppdatert: 2018-11-08
    3. Robust linear precoder for coordinated multipoint joint transmission under limited backhaul with imperfect CSI
    Åpne denne publikasjonen i ny fane eller vindu >>Robust linear precoder for coordinated multipoint joint transmission under limited backhaul with imperfect CSI
    2014 (engelsk)Inngår i: 2014 11TH INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATIONS SYSTEMS (ISWCS), 2014, s. 138-143Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Coordinated Multipoint (COMP) transmission provides high theoretic gains in spectral efficiency, in particular with coherent linear Joint Transmission (JT) to multiple users. However, this requires high backhaul capacity. If the backhaul requirement cannot be met by the system, then CoNIP gains decrease as the linear precoder matrix must be adjusted to include zeros. To minimize the loss of CoMP gains, all elements in the precoder should be adjusted as zeros are added to the precoder. We here propose a low complexity method for adjusting a precoder matrix when some elements are required to be zero, with respect to a robust MSE criterion. This is done by introducing penalties on specific precoder matrix elements. This generalized MSE criterion can then be used as a low complexity tool for optimizing e.g. with respect to sum-rate. Results show that this does indeed provide a better solution than if zeros are added separately. It is especially beneficial for cell edge users, i.e. for the same users that can gain the most from JT CoNIP.

    HSV kategori
    Forskningsprogram
    Elektroteknik med inriktning mot signalbehandling
    Identifikatorer
    urn:nbn:se:uu:diva-235007 (URN)000363906500027 ()978-1-4799-5863-4 (ISBN)
    Konferanse
    International Symposium on Wireless Communication Systems ISWCS, Barcelona, Spanien, 25-29 Augusti
    Tilgjengelig fra: 2014-10-28 Laget: 2014-10-28 Sist oppdatert: 2018-03-07bibliografisk kontrollert
    4. Joint reference signal design and Kalman/Wiener channel estimation for FDD massive MIMO. Extended Report Version.
    Åpne denne publikasjonen i ny fane eller vindu >>Joint reference signal design and Kalman/Wiener channel estimation for FDD massive MIMO. Extended Report Version.
    2017 (engelsk)Rapport (Annet vitenskapelig)
    sted, utgiver, år, opplag, sider
    Uppsala: Signals and Systems, Uppsala University, 2017
    Serie
    Report r1701
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-330705 (URN)
    Tilgjengelig fra: 2017-10-03 Laget: 2017-10-03 Sist oppdatert: 2018-03-07
    5. Kalman smoothing for irregular pilot patterns; A case study for predictor antennas in TDD systems
    Åpne denne publikasjonen i ny fane eller vindu >>Kalman smoothing for irregular pilot patterns; A case study for predictor antennas in TDD systems
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    For future large-scale multi-antenna systems, channel orthogonal downlink pilots are not feasible due to extensive overhead requirements. Instead, channel reciprocity can be utilized in time division duplex (TDD) systems so that the downlink channel estimates can be based on pilots transmitted during the uplink. User mobility affects the reciprocity and makes the channel state information outdated for high velocities and/or long downlink subframe durations. Channel extrapolation, e.g. through Kalman prediction, can reduce the problem but is also limited by high velocities and long downlink subframes. An alternative solution has been proposed where channel predictions are made with the help of an extra antenna, e.g. on the roof of a car, so called predictor antenna, with the primary objective to measure the channel at a position that is later encountered by the rearward antenna(s). The predictor antenna is not directly limited by high velocities and allows the channel in the downlinks to be interpolated rather than extrapolated. One remaining challenge here is to obtain a good interpolation of the uplink channel estimate, since a sequence of uplink reference signals (pilots) will be interrupted by downlink subframes. We here evaluate a Kalman smoothing estimate of the downlink channels and compare it to a cubic spline interpolation. These results are compared to results where uplink channels are estimated through Kalman filters and predictors. Results are based on measured channels and show that with Kalman smoothing, predictor antennas can enable accurate channel estimates for a longer downlink period at vehicular velocities.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-344267 (URN)
    Tilgjengelig fra: 2018-03-06 Laget: 2018-03-06 Sist oppdatert: 2018-03-07
  • 5.
    Apelfröjd, Rikke
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Björsell, Joachim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sternad, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Phan Huy, D-T
    Kalman smoothing for irregular pilot patterns: A case study for predictor antennas in TDD systems2018Inngår i: 2018 IEEE 29th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    For future large-scale multi-antenna systems, channel orthogonal downlink pilots are not feasible due to extensive overhead requirements. Instead, channel reciprocity can be utilized in time division duplex (TDD) systems so that the downlink channel estimates can be based on pilots transmitted during the uplink. User mobility affects the reciprocity and makes the channel state information outdated for high velocities and/or long downlink subframe durations. Channel extrapolation, e.g. through Kalman prediction, can reduce the problem but is also limited by high velocities and long downlink subframes. An alternative solution has been proposed where channel predictions are made with the help of an extra antenna, e.g. on the roof of a car, so called predictor antenna, with the primary objective to measure the channel at a position that is later encountered by the rearward antenna(s). The predictor antenna is not directly limited by high velocities and allows the channel in the downlinks to be interpolated rather than extrapolated. One remaining challenge here is to obtain a good interpolation of the uplink channel estimate, since a sequence of uplink reference signals (pilots) will be interrupted by downlink subframes. We here evaluate a Kalman smoothing estimate of the downlink channels and compare it to a cubic spline interpolation. These results are also compared to results where uplink channels are estimated through Kalman filters and predictors. Results are based on measured channels and show that with Kalman smoothing, predictor antennas can enable accurate channel estimates for a longer downlink period at vehicular velocities. The gaps in the uplink pilot stream, due to downlink subframes, can have durations that correspond to a vehicle movement of up to 0.75 carrier wavelengths in space, for Rayleigh-like non-line-of-sight fading.

  • 6.
    Apelfröjd, Rikke
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Zirwas, Wolfgang
    Nokia Bell Labs, D-81541 Munich, Germany.
    Sternad, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Low-Overhead Cyclic Reference Signals for Channel Estimation in FDD Massive MIMO2019Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 67, nr 5, s. 3279-3291Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Massive multiple input multiple output (MIMO) transmission and coordinated multipoint transmission are candidate technologies for increasing data throughput in evolving 5G standards. Frequency division duplex (FDD) is likely to remain predominant in large parts of the spectrum below 6 GHz for future 5G systems. Therefore, it is important to estimate the downlink FDD channels from a very large number of antennas, while avoiding an excessive downlink reference signal overhead. We here propose and investigate a three part solution. First, massive MIMO downlinks use a fixed grid of beams. For each user, only a subset of beams will then be relevant, and require estimation. Second, sets of coded reference signal sequences, with cyclic patterns over time, are used. Third, each terminal estimates its most relevant channels. We here propose and compare a linear mean square estimation and a Kalman estimation. Both utilize frequency and antenna correlation, and the later also utilizes temporal correlation. In extensive simulations, this scheme provides channel estimates that lead to an insignificant beamforming performance degradation as compared to full channel knowledge. The cyclic pattern of coded reference signals is found to be important for reliable channel estimation, without having to adjust the reference signals to specific users.

  • 7.
    Arfwedson, Viktor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Improving eciency of EMC ImmunityMonitoring of RBS using a FPGA basedinstrument2014Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    A test system for Immunity testing of Ericsson's LTE radiobase station (RBS) was built using a National Instruments(NI) PXI chassis tted with a vector signal transceiver (VST)module and a PC controller module. A program made in Lab-VIEW and MATLAB was run on the controller module in thePXI chassis. The tasks of the program was, on one hand, tocontrol the VST which was used to record the signal emittedfrom the RBS and on the other hand, to process the signal anddetermine its quality by acquiring the bits transmitted. Functionalityenabling the VST to transmit a given signal was alsoincluded in the program. The built system performed up toninety times faster than the old system but lacked turbo decodingnecessary to correctly determine bit error ratio (BER)and block error ratio (BLER). The performance of the systemleaves room for adding time consuming processes such as turbodecoding later on and by examining the undecoded bits the signalquality can still be measured. The program handles both1tx and 2tx signals.

  • 8.
    Augustine, Robin
    Université Paris-Est.
    Electromagnetic modelling of human tissues and its application on the interaction between antenna and human body in the BAN context2009Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In this age of wireless technology, Body Area networks (BAN) is revolutionising the concept of patient care and health monitoring. BAN provides people good assessment of their health status at any time, wherever they are physically. The increased interest in developing effective body (in, on & off) communication systems made phantoms which can mimic the electrical properties of an actual human body necessary. Wearable antennas which are the indispensable part of BAN got to be low pro file and above all influences that human body can make. There should also be a way to reduce the effect of antennas on human body namely specific absorption rate (SAR). In this work effort has been made to develop phantoms suitable for both On body and In body communications. The base materials which are selected for the study are of biological origin (bio ceramics and biopolymers) whose behaviour is closer to that of human tissues. As these phantoms are biocompatible they are essentially non toxic where the conventionally available phantoms are toxic in nature. Different kinds of low profile conformal wearable antennas working at 2.4GHz ISM band were developed and studied in the BAN perspective. Antennas suffer much in terms of matching and efficiency when they are in contact or in the premises of human body. This is a major hurdle in the way to setting up a good body communication network. This work encompasses various techniques adopted to limit the body interferences to an acceptable level. The techniques adopted (Such as Backing Ground Plane, High Impedance Surface & Polymeric Ferrite Sheets) proved to be effective in reducing the sway in antenna characteristics when they are mounted on body. Specific absorption rate is also brought to acceptable levels and thus avoiding the formation of hot spots due to microwave absorption. A safer and cost effective BAN can be set up using this work which will lead to a safer, mobile and healthy future.

  • 9. Augustine, Robin
    From human skin permittivity measurements up to 65 GHz to development of skinequivalentphantoms for body-centric applications2011Konferansepaper (Fagfellevurdert)
  • 10.
    Aziz, Imran
    Uppsala University.
    Irradiation Hardness Investigations of 60 GHz Transceiver Chips for High Energy Physics Experimentations2019Konferansepaper (Fagfellevurdert)
  • 11.
    Aziz, Imran
    et al.
    Uppsala University.
    Ojefors, Erik
    Dahlbäck, Robin
    Rydberg, Anders
    Engblom, Gunnar
    Dancila, Dragos
    Broadband Connected Slots Phased Array Feeding a High Gain Lens Antenna at 60 GHz2019Konferansepaper (Fagfellevurdert)
  • 12.
    Aziz, Imran
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Dancila, Dragos
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Electromagnetically Coupled Multilayer Patch Antenna for 60 GHz Communications2018Konferansepaper (Fagfellevurdert)
  • 13.
    Bergslilja, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Performance evaluation of IQ-modulator ADL5375at 5.8 GHz and its effect on transmitterperformance in a telecommunications system2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Because of the tough competition inthe telecom business there is aconstant push for higher capacity anddata rates and the companies producingthe telecommunications equipment needmore cost effective products to stayahead of competitors. It is thereforeinteresting to evaluate thepossibilities to use unlicensedfrequency bands at higher frequenciesas a complement to the traditionallower frequency bands. This study isfocusing on the 5.8 GHz band, which ismainly used for WLAN applications. Akey component in most transmitter (TX)designs is is the quadraturemodulator, which upconverts theinformation signal to desired carrierfrequency. In this study an attempt toevaluate the commercially availablequadrature modulator ADL5375 at 5.8GHz. An AWR Visual System Simulator(VSS) model based on measurements ofkey parameters of ADL5375 isconstructed. An attempt is made to seewhether a TX design can pass thespecifications set by 3rd GenerationPartnership Project (3GPP) for theLong Term Evolution (LTE) standard. Totest this an LTE signal source wasalso constructed. No certainconclusions can be drawn withoutputting the modulator in a complete(TX) design but the results indicatethat it might be possible to use it ina (TX) design for the 5.8 GHz band.

  • 14.
    Bergström, Sofia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    The Impact of Antennas on Radiolink Performance in Frequency Hopping Scenarios2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This paper investigates how the communication performance of frequency hopping systems are affected by the antenna parameters. The data are generated from Antenna Toolbox in Matlab for the case of two dipole antennas is free space. Non-orthogonal and orthogonal frequency hopping are used and the statistical impact from the antenna on the SINR is investigated. The results can be used to see the wave propagation margin and also see the effects of out-of-bands emissions in frequency hopping systems.

    The numerical generated model is compared to two isotropic antenna models and it shows that the isotropic models are relatively good despite its simplicity in this case. It does however not capture the spread caused by the directivity. Another model is created which mimic the numerical generated statistical distribution. This model uses the theoretical probability of a collision for both orthogonal and non-orthogonal frequency hopping. The model also uses mean values of directivity, s-parameters and the spread of the gain to calculate a statistical antenna model. This model is better than the isotropic for the tested cases and shows that it is possible to generate a statistical model.

  • 15. Biasson, A
    et al.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Zorzi, M
    A decentralized optimization framework for energy harvesting devices2018Inngår i: IEEE Transactions on Mobile Computing, ISSN 1536-1233, E-ISSN 1558-0660, Vol. 17, nr 11, s. 2483-2496Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Designing decentralized policies for wireless communication networks is a crucial problem, which has only been partially solved in the literature so far. In this paper, we propose a Decentralized Markov Decision Process (Dec-MDP) framework to analyze a wireless sensor network with multiple users which access a common wireless channel. We consider devices with energy harvesting capabilities, that aim at balancing the energy arrivals with the data departures and with the probability of colliding with other nodes. Over time, an access point triggers a SYNC slot, wherein it recomputes the optimal transmission parameters of the whole network, and distributes this information. Every node receives its own policy, which specifies how it should access the channel in the future, and, thereafter, proceeds in a fully decentralized fashion, with no interactions with other entities in the network. We propose a multi-layer Markov model, where an external MDP manages the jumps between SYNC slots, and an internal Dec-MDP computes the optimal policy in the short term. We numerically show that, because of the harvesting, stationary policies are suboptimal in energy harvesting scenarios, and the optimal trade-off lies between an orthogonal and a random access system.

  • 16.
    Biasson, Alessandro
    et al.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6b, I-35131 Padua, Italy..
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Zorzi, Michele
    Univ Padua, Dept Informat Engn, Via Gradenigo 6b, I-35131 Padua, Italy..
    Decentralized Transmission Policies for Energy Harvesting Devices2017Inngår i: 2017 Ieee Wireless Communications And Networking Conference Workshops (WCNCW), IEEE , 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The problem of finding decentralized transmission policies in a wireless communication network with energy harvesting constraints is formulated and solved using the decentralized Markov decision process framework. The proposed policy defines the transmission strategies of all devices so as to correctly balance the collision probabilities with the energy constraints. After an initial coordination phase, in which the network parameters are initialized for all devices, every node proceeds in a fully decentralized fashion. We numerically show that, unlike in the case without energy constraints where a fully orthogonal scheme can be shown to be optimal, in the presence of energy harvesting this is no longer the best choice, and the optimal strategy lies between an orthogonal and a completely symmetric system.

  • 17.
    Biswas, Sinchan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Shirazinia, Amirpasha
    Analyt & AI Grp, S-17062 Stockholm, Sweden.
    Sum Throughput Maximization in a Cognitive Multiple Access Channel With Cooperative Spectrum Sensing and Energy Harvesting2019Inngår i: IEEE TRANSACTIONS ON COGNITIVE COMMUNICATIONS AND NETWORKING, ISSN 2332-7731, Vol. 5, nr 2, s. 382-399Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper focuses on the problem of sensing throughput optimization in a fading multiple access cognitive radio (CR) network, where the secondary user (SU) transmitters participate in cooperative spectrum sensing and are capable of harvesting energy and sharing energy with each other. We formulate the optimization problem as a maximization of the expected achievable sum-rate over a finite horizon, subject to an average interference constraint at the primary receiver, peak power constraints, and energy causality constraints at the SU transmitters. The optimization problem is a non-convex, mixed integer non-linear program (MINLP) involving the binary action to sense the spectrum or not, and the continuous variables, such as the transmission power, shared energy, and sensing time. The problem is analyzed under two different assumptions on the available information pattern: 1) non-causal channel state information (CSI), energy state information (ESI), and infinite battery capacity and 2) the more realistic scenario of the causal CSI/ESI and finite battery. In the non-casual case, this problem can be solved by an exhaustive search over the decision variable or an MINLP solver for smaller problem dimensions, and a novel heuristic policy for larger problems, combined with an iterative alternative optimization method for the continuous variables. The causal case with finite battery is optimally solved using a dynamic programming (DP) methodology, whereas a number of sub-optimal algorithms are proposed to reduce the computational complexity of DP. Extensive numerical simulations are carried out to illustrate the performance of the proposed algorithms. One of the main findings indicates that the energy sharing is more beneficial when there is a significant asymmetry between average harvested energy levels/channel gains of different SUs.

  • 18.
    Björsell, Joachim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Long Range Channel Predictions for Broadband Systems: Predictor antenna experiments and interpolation of Kalman predictions2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The field of wireless communication is under massive development and the demands on the cellular system, especially, are constantly increasing as the utilizing devices are increasing in number and diversity. A key component of wireless communication is the knowledge of the channel, i.e, how the signal is affected when sent over the wireless medium. Channel prediction is one concept which can improve current techniques or enable new ones in order to increase the performance of the cellular system. Firstly, this report will investigate the concept of a predictor antenna on new, extensive measurements which represent many different environments and scenarios. A predictor antenna is a separate antenna that is placed in front of the main antenna on the roof of a vehicle. The predictor antenna could enable good channel prediction for high velocity vehicles. The measurements show to be too noisy to be used directly in the predictor antenna concept but show potential if the measurements can be noise-filtered without distorting the signal. The use of low-pass filter and Kalman filter to do this, did not give the desired results but the technique to do this should be further investigated.

    Secondly, a interpolation technique will be presented which utilizes predictions with different prediction horizon by estimating intermediate channel components using interpolation. This could save channel feedback resources as well as give a better robustness to bad channel predictions by letting fresh, local, channel predictions be used as quality reference of the interpolated channel estimates. For a linear interpolation between 8-step and 18-step Kalman predictions with Normalized Mean Square Error (NMSE) of -15.02 dB and -10.88 dB, the interpolated estimates had an average NMSE of -13.14 dB, while lowering the required feedback data by about 80 %. The use of a warning algorithm reduced the NMSE by a further 0.2 dB. It mainly eliminated the largest prediction error which otherwise could lead to retransmission, which is not desired. 

  • 19.
    Björsell, Joachim
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sternad, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Grieger, Michael
    AIRRAYS Wireless Solut Dresden, Dresden, Germany.
    Using predictor antennas for the prediction of small-scale fading provides an order-of-magnitude improvement of prediction horizons2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Our aim is to investigate long range predictions (up to several wavelengths) of the small-scale fading of radio channels. The purpose is to enable advanced 5G downlink transmission schemes that require accurate channel state information at transmitters, such as massive MIMO and coherent joint transmission, for vehicular users. We here present a proof of concept for the recently introduced predictor antenna scheme which promises a significant increase in prediction horizon compared to conventional techniques. Predictor antennas utilize the exterior of moving vehicles by placing antenna arrays on top of their roofs. They are used to estimate the fading radio channels that are encountered later by the following antennas. The level of predictability is determined by the correlation between the channel measured at the predictor antenna and the channel that is later encountered by the following antennas when they move to that position. That correlation, and the resulting prediction errors, are assessed on a large set of measurement data sampled at vehicular velocities, at a carrier frequency of 2.53 GHz, from a multitude of urban fading environments. These represent a wide variety of propagation environments, including narrow and wide roads, intersections, dense urban environments and residential areas. Using low-pass filtered predictor antenna measurements, the obtained average prediction Normalized Mean Squared Error (NMSE) is -11 dB for prediction horizons of 0.25 wavelengths and -8.5 dB for horizons of 3 wavelengths. This represents an order of magnitude increase of the prediction horizons as compared to time-series prediction that typically, in practice, fails to work for prediction beyond 0.3 wavelengths in space. As a result, we have a tool that enables advanced 5G transmit schemes for vehicular users and vehicle-to-infrastructure links.

  • 20.
    Carlos, Pérez Penichet
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorarkitektur och datorkommunikation.
    Hermans, Frederik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorarkitektur och datorkommunikation.
    Voigt, Thiemo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorarkitektur och datorkommunikation.
    On Limits of Constructive Interference in Backscatter Systems2017Inngår i: Global Internet of Things Summit (GIoTS), 2017, IEEE, 2017, s. 178-182Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Backscatter communication reduces the energy consumption of resource-constrained sensors and actuators by several orders of magnitude as it avoids the resource-consuming need to generate a radio wave. Many backscatter systems and applications suffer from low communication range. By exploiting the collective power of several tags that transmit the same data simultaneously, constructive interference may help to remedy this problem and increase the communication range. When several tags backscatter the same signal simultaneously it is not necessarily true that constructive interference occurs. As our theoretical results and previous work indicate the interference might also be destructive. Our experimental results on real hardware suggest that exploiting constructive interference to increase the communication range requires careful coordination which is difficult in decentralized settings.

  • 21.
    Cooray, Vernon
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Rachidi, Farhad
    Swiss Fed Inst Technol, EMC Lab, CH-1015 Lausanne, Switzerland.
    Rubinstein, Marcos
    Haute Ecole Ingn & Gest Canton Vaud, Inst Informat & Commun Technol, CH-1401 Yverdon, Switzerland.
    Formulation of the Field-to-Transmission Line Coupling Equations in Terms of Scalar and Vector Potentials2017Inngår i: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 59, nr 5, s. 1586-1591Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    More than 60 years ago, Prof. S. Rusck introduced a coupling model to take into account the interaction of lightning-generated electromagnetic fields with overhead power transmission and distribution lines. The model which assumes that the ground is perfectly conducting has served the power system research community for many decades. Recently, it was found that this model is not complete because some of the forcing terms in the relevant transmission line equations, which are based purely on the scalar and vector potentials, were missing. In the present paper, the correct transmission line equations pertinent to the interaction of external electromagnetic fields with overhead lines, described in terms of scalar and vector potentials, are derived by incorporating the effects of a finitely conducting ground. The model presented in this paper can be considered as a correction and an extension of the Rusck model to account for a finitely conducting ground.

  • 22.
    Dancila, Dragos
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Beuerle, Bernhard
    Micro and Nanosystems, Royal Institute of Technology (KTH).
    Shah, Umer
    Micro and Nanosystems, Royal Institute of Technology (KTH).
    Augustine, Robin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Gustafsson, Andreas
    Department of Radar Systems, Swedish Defence Research Agency (FOI).
    Oberhammer, Joachim
    Micro and Nanosystems, Royal Institute of Technology (KTH).
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Leaky Wave Antenna at 300 GHz in KTH’s Micromachined Waveguide Technology2018Konferansepaper (Annet vitenskapelig)
  • 23.
    Dancila, Dragos
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Moossavi, Reza
    Mittuniversitetet, Avdelningen för Elektronikkonstruktion (EKS).
    Siden, Johan
    Mittuniversitetet.
    Zhang, Zhibin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Anders, Rydberg
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Antennas on Paper Using Ink-Jet Printing of Nano-Silver Particles for Wireless Sensor Networks in Train Environment2016Inngår i: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 58, nr 4, s. 754-759Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents the design, manufacturing and measurements of antennas on paper, realized using ink-jetprinting of conductive inks based on nano-silver particles (nSPs). The extraction of the substrate characteristicssuch as the dielectric constant and dielectric loss is performed using a printed ring resonator technique. Thecharacterization of the nSPs conductive inks assesses different parameters as sintering time and temperature.Two antennas are realized corresponding to the most common needs for Wireless Sensor Networks (WSN) inTrains Environment. The first one is a patch antenna characterized by a broadside radiation pattern and suitedfor operation on metallic structures. The second one is a quasi-yagi antenna, with an end fire radiation patternand higher directivity, without requiring a metallic ground plane. Both antennas present a good matching (S11 < -20 dB and S11 < -30 dB, respectively) and acceptable efficiency (55 % and 45 %, respectively) for the papersubstrate used at the center frequency of 2.4 GHz, corresponding to the first channel of the IEEE 802.15.4 band.

  • 24.
    Deng, Tao
    et al.
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu 610031, Sichuan, Peoples R China.
    Fan, Pingzhi
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu 610031, Sichuan, Peoples R China.
    Yuan, Di
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Optimizing Retention-Aware Caching in Vehicular Networks2019Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 67, nr 9, s. 6139-6152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Caching is an effective way to address the challenges due to explosive data traffic growth and massive device connectivity in fifth-generation (5G) networks. Currently, few works on caching pay attention to the impact of the time duration for which content is stored, called retention time, on caching optimization. The research on retention time is motivated by two practical issues, i.e., flash memory damage and storage rental cost in cloud networks, together giving rise to the storage cost. How to optimize caching contents taking the storage cost into consideration is a challenging problem, especially for the scenarios with cache-enabled mobile nodes. In this paper, a retention-aware caching problem (RACP) in vehicular networks is formulated, considering the impact of the storage cost. The problem's complexity analysis is provided. For symmetric cases, an optimal dynamic programming (DP) algorithm with polynomial time complexity is derived. For general cases, a low complexity and effective retention aware multi-helper caching algorithm (RAMA) is proposed. Numerical results are used to verify the effectiveness of the algorithms.

  • 25.
    Ek, Patrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Deployment of Indoor Small-Cells for 4G mobile Broadband2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis presents an investigation of the impact of indoor small-cells. It is expected

    that small-cells will be able to increase the throughput and capacity for the existing

    networks. A deployment algorithm is presented with focus on offloading traffic from

    the macro layer. The performance of the deployments created with the proposed

    algorithm, is compared with a reference deployment. The different deployments are

    then simulated in a real network simulator, which performs static simulations in 3

    dimension using the theory of multiple knife-edge diffraction. The small-cells increased

    the throughput and capacity remarkably and additional gains were obtained with the

    proposed algorithm. The thesis also includes strategies for small-cell deployment.

  • 26.
    Ericsson, Elias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Adaptive Wireless Transmission System2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 27.
    Eriksson, Markus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Olofsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    On Long-Term Statistical Dependences in Channel Gains for Fixed Wireless Links in Factories2016Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 64, nr 7, s. 3078-3091Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reliability and throughput in an industrial wireless sensor network can be improved by incorporating the predictions of channel gains when forming routing tables. Necessary conditions for such predictions to be useful are that statistical dependences exist between the channel gains and that those dependences extend over a long enough time to accomplish a rerouting. In this paper, we have studied such long-term dependences in channel gains for fixed wireless links in three factories. Long-term fading properties were modeled using a switched regime model, and Bayesian change point detection was used to split the channel gain measurements into segments. In this way, we translated the study of long-term dependences in channel gains into the study of dependences between fading distribution parameters describing the segments. We measured the strengths of the dependences using mutual information and found that the dependences exist in a majority of the examined links. The strongest dependence appeared between mean received power in adjacent segments, but we also found significant dependences between segment lengths. In addition to the study of statistical dependences, we present the summaries of the distribution of the fading parameters extracted from the segments, as well as the lengths of these segments.

  • 28.
    Flink, Oskar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Wireless electrocardiogram transmission based on ultra wideband radio2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Ultra wideband (UWB) communications has been a subject of much discussion over the last decade. The method of UWB has had a hard time to establish itself among other methods such as Bluetooth and WiFi but as internet of things (IoT) gains a foothold in our daily lives, UWB has presented some new application areas. These application areas are, among other things, self driving cars, energy efficient data transfer, health care applications, sensor networks and real time location systems. This project aims to use UWB communications to real-world applications, specifically, electrocardiography (ECG) - an application in health care in this project, and develop a prototype for the application. The prototype consists of two Android smart phones and two UWB modules (EVK1000 evaluation kits from DecaWave, Inc). Each smartphone connects a UWB module so that the two smart phones, one as sender and the other as receiver, can communicate directly through UWB radios. This is intended to serve as a proof-of-concept that UWB devices are well suited for short range data transfer applications. The result achieved by the project is an android application along with sending and receiving programs for the development boards by Decawave and additional information regarding UWB and its uses. The results also include a comparison of UWB, Bluetooth and WiFi as of todays standard. The goal of the project is to learn how android applications are programmed, how UWB is used in todays technology and how to program and use development boards presented by companies. The prototype has been built and shown that 12-lead simulated ECGsignals from the sender can be transfered to the receiver through the UWB communications. The work includes programming (in C) the two UWB modules for UWB communications, and Java for the android applications (programs) on the smart phones. The Android application is handling transmission of ECG signals to the sending UWB module and then receiving them from the receiving UWB module as well as displaying them on the receiver. The future work to continue the present project is to replace the sending smart phone by an ECG device that sends real ECG signals.

  • 29. Goodwin, Graham
    et al.
    Cea, Mauricio
    Lau, Katrina
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Control challenges in mobile telecommunications2014Inngår i: The Impact of Control Technology / [ed] Samad, Tariq; Annaswamy, Anuradha, IEEE Control Systems Society , 2014, 2ndKapittel i bok, del av antologi (Fagfellevurdert)
  • 30.
    Granbom, Markus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Förenklad felinformation på trafikinformationsutrustning2013Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    This thesis lays the foundation of the future routines of effective error repotring fortraffic devices in the raiway sector.If a device, for example a timetable display, stops working it is vital that the device isfixed as fast as possible so that the travelers dont miss any important information.The methods that are used today are old and not very effective. It can take time forthe repairmen to find the right device or locating the broken component. At the sametime he is supposed to maintain telephone contact with central control throughoutthe whole session.The need for a new, more effective, system is vital to make the whole repair pfocessmore effective and let the repairmen work without having to contact the centralcontrol by phone.I started this work by examining the possibilities of assigning every object with aunique identifier (ID tag) that could be accessed by a manual scan device. The ideawas that the ID tag could holw information about the object and be obtained byscanning the ID and get the information presented on a mobile device.The work also included building a internet application that enabled the reader to seeand change the information on the ID tag.The result was a database that stored information of different objects which could beobtained by scanning the ID tag and presented by a internet application.

  • 31. Grinchtein, Olga
    et al.
    Carlsson, Mats
    Pearson, Justin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    A constraint optimisation model for analysis of telecommunication protocol logs2015Inngår i: Tests and Proofs: TAP 2015, Springer, 2015, s. 137-154Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Testing a telecommunication protocol often requires protocol log analysis. A protocol log is a sequence of messages with timestamps. Protocol log analysis involves checking that the content of messages and timestamps are correct with respect to the protocol specification. We model a protocol specification using constraint programming (MiniZinc), and we present an approach where a constraint solver is used to perform protocol log analysis. Our case study is the Public Warning System service, which is a part of the Long Term Evolution (LTE) 4G standard. We were able to analyse logs containing more than 3000 messages with more than 4000 errors.

  • 32.
    Grudén, Mathias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wireless Sensor Network and Radio Wave Propagation in Harsh Environments2012Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This licentiate thesis cover two important subjects regarding the application of wireless sensor networks (WSNs). Both subjects are related to propagation mechanisms. The first subject is what the radio channel looks like and how it behaves. In this case three different, and extreme, environments are measured and characterized - a train, a half scale jet engine fan and a full scale military jet engine. The train environment is characterized by measure the path loss and fading over distance. For the case with the jet engines, difficulties were found to measure the path loss over distance, so in this case stationary antennas were used, but with the engine running. Each of these shows an extreme type of fading, also known as Rayleigh fading. For the case of jet engine at full speed (about 10 000 rpm), it was shown that the time between two consecutive fading dips where only 290 μs, which is about twice the length of a data package from the WSN involved in this project. The Rayleigh distributed amplitude fading occurs when there is a multipath environment, the radio waves propagate several different paths between the transmitter and receiver, which causes a superposition at the receiver. When having Rayleigh fading, the performance of the radio link is greatly reduced. When applying a WSN in this type of environment, the use of several antennas will improve the received power of the signal. This is done by adding extra antennas to a wireless system and in a clever way combine the signals, or select one of two signals from the antennas. In a book chapter and in a paper presented in the thesis, a new and low energy type of diversity is described. The performance of this new type of diversity is shown by having a two branch diversity and discretely shifting the phase of each branch before combining them. In this case, four relative phase shifts are performed during each symbol received. When performing a combining like this, the energy is saved by not having any decision circuitry. By using this type of diversity and using a 90 % signal reliability and an ideal environment, the diversity gain is 5.5 dB for an averaging detector and 10.3 dB for a peak detector.  The drawback with this system is that it is only limited for systems using simple types of amplitude (ASK) or frequency (FSK) modulation.

    Delarbeid
    1. Reliability Experiments for Wireless Sensor Networks in Train Environment
    Åpne denne publikasjonen i ny fane eller vindu >>Reliability Experiments for Wireless Sensor Networks in Train Environment
    Vise andre…
    2009 (engelsk)Inngår i: European Microwave Week (EuMWeek), Second European Wireless Technology Conference, EuWIT, 2009, s. 37-40Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Forskningsprogram
    Elektroteknik med inriktning mot signalbehandling; Teknisk fysik med inriktning mot mikrovågsteknik
    Identifikatorer
    urn:nbn:se:uu:diva-120593 (URN)
    Konferanse
    European Microwave Week (EuMWeek), Second European Wireless Technology Conference, EuWIT
    Prosjekter
    WISENET
    Tilgjengelig fra: 2010-03-15 Laget: 2010-03-15 Sist oppdatert: 2016-04-14bibliografisk kontrollert
    2. Antenna diversity with opportunistic combining for ASk systems with single channel receivers
    Åpne denne publikasjonen i ny fane eller vindu >>Antenna diversity with opportunistic combining for ASk systems with single channel receivers
    2010 (engelsk)Inngår i: Proceedings of the Fourth European Conference on Antennas and Propagation (EuCAP), 2010, s. 1-5Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-138838 (URN)
    Konferanse
    Fourth European Conference on Antennas and Propagation (EuCAP)
    Prosjekter
    WISENET
    Tilgjengelig fra: 2010-12-20 Laget: 2010-12-20 Sist oppdatert: 2016-04-18bibliografisk kontrollert
    3. Diversity Techniques for Robustness and Power Awareness in Wireless Sensor Systems for Railroad Transport Applications
    Åpne denne publikasjonen i ny fane eller vindu >>Diversity Techniques for Robustness and Power Awareness in Wireless Sensor Systems for Railroad Transport Applications
    2011 (engelsk)Inngår i: Sustainable Wireless Sensor Networks / [ed] Winston Seah and Yen Kheng Tan, InTech Open Publishers , 2011, 1, s. 75-95Kapittel i bok, del av antologi (Fagfellevurdert)
    sted, utgiver, år, opplag, sider
    InTech Open Publishers, 2011 Opplag: 1
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-159204 (URN)978-953-307-297-5 (ISBN)
    Prosjekter
    wisenet
    Tilgjengelig fra: 2011-09-25 Laget: 2011-09-25 Sist oppdatert: 2016-04-20bibliografisk kontrollert
    4. Wireless sensor networks for aircraft engines
    Åpne denne publikasjonen i ny fane eller vindu >>Wireless sensor networks for aircraft engines
    Vise andre…
    2011 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-138847 (URN)
    Konferanse
    Smart Systems Integration Conference, Dresden, Germany, 22-23.03.2011
    Prosjekter
    wisenet
    Tilgjengelig fra: 2010-12-20 Laget: 2010-12-20 Sist oppdatert: 2016-04-20bibliografisk kontrollert
    5. Measurements and Simulations of Wave Propagation for Wireless Sensor Networks in Jet Engine Turbines
    Åpne denne publikasjonen i ny fane eller vindu >>Measurements and Simulations of Wave Propagation for Wireless Sensor Networks in Jet Engine Turbines
    2011 (engelsk)Inngår i: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 10, s. 1139-1142Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In this letter, measurements and simulations of wave propagation inside a jet engine fan have been performed. The investigation was done using both EM simulations of different cases of propagation inside the engine and by measuring the corresponding cases inside a half-scale model of a jet engine fan. The average path loss was calculated, and the shapes of the fading distributions were extracted. The time between two consecutive fading dips was measured in the empirical part. Measurements were performed with engine speeds of both 30 and 60 rpm and were shown to be linearly scalable from 60 rpm to full speed of 10 000 rpm. The results showed an average path loss of about 55 dB. When scaling the measurements from 60 rpm to full-speed rotation of about 10 000 rpm, the fading was so severe that the time slot between consecutive fading dips was limited to 290 mu s.

    Emneord
    Communication channels, electromagnetic propagation, propagation losses, radio communication, radiowave propagation
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-161778 (URN)10.1109/LAWP.2011.2171309 (DOI)000296260200004 ()
    Tilgjengelig fra: 2011-11-21 Laget: 2011-11-17 Sist oppdatert: 2017-12-08bibliografisk kontrollert
  • 33.
    Grudén, Mathias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wireless Sensor Network Systems in Harsh Environments and Antenna Measurement Techniques2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Wireless sensor network (WSN) has become a hot topic lately. By using WSN things that previously were difficult or impossible to measure has now become available. One of the main reasons using WSN for monitoring is to save money by cost optimization and/or increase safety by letting the user knowing the physical status of the monitored structure. This thesis considers four main topics, empirical testing of WSN in harsh environments, antenna designs, antenna measurements and radio environment emulation.

    The WSN has been tested in train environment for monitoring of ball bearings and inside jet engines to monitor strain of blades and temperatures. In total, two investigations have been performed aboard the train wagon and one in the jet engine. The trials have been successful and provide knowledge of the difficulties with practical WSN applications. The key issues for WSN are robust communication, energy management (including scavenging) and physical robustness.

    For the applications of WSN in harsh environments antennas has to be designed. In the thesis, two antennas has been designed, one for train environment and one for the receiver in the jet engine. In the train environment, a more isotropic radiation pattern is preferable; hence a small dual layered patch antenna is designed. The antenna is at the limit of being electrically small; hence slightly lower radiation efficiency is measured. For the WSN in the jet engine, a directive patch array is designed on an ultra-thin and flexible substrate. The thin substrate of the antenna causes rather lower radiation efficiency. But the antenna fulfils the requirements of being conformal and directive.

    In reverberation chambers are used to measure antennas, but there are difficulties to provide a realistic radio environment, for example outdoor or on-body. In this thesis, a large reverberation chamber is designed and verified. It enables measurement between 400 MHz and 3 GHz. Also, a sample selection method is designed to provide a post processing possibilities to emulate the radio environment inside the chamber. The method is to select samples from a data set that corresponds to a desired probability density function. The method presented in this thesis is extremely fast but the implementation of the method is left for future research.

    Delarbeid
    1. Field Operational Testing for Safety Improvement of Freight Trains using Wireless Monitoring by Sensor Network
    Åpne denne publikasjonen i ny fane eller vindu >>Field Operational Testing for Safety Improvement of Freight Trains using Wireless Monitoring by Sensor Network
    Vise andre…
    2013 (engelsk)Inngår i: IET Wireless Sensor Systems, ISSN 2043-6386, E-ISSN 2043-6394Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Today, the majority of wagon failures on railroad systems are because of the poor maintenance of ball bearings, which causes emergent stops and delays. The existing stationary detectors, lack in predicting failures which cause troubles in scheduling maintenance. During the fall of 2011, a trial was performed by applying a wireless sensor network (WSN) aboard a train wagon with the objective to demonstrate a proof of concept for monitoring the temperature of ball bearings aboard the train wagon. This trial investigates several key aspects when applying sensor networks such as radio wave propagation, energy scavenging and performance of the WSN aboard the wagon. Two wireless links were used in the WSN. The aboard network communicates at 2.45 GHz, and the external communication is an 868 MHz radio frequency identification radio link. Since the energy in the WSN node is limited, appropriate energy scavenging devices are also presented and evaluated in a lab environment. Effort has been made to overcome these problems. The energy consumption in the network is still a problem; the most promising energy scavenging technique is piezoelectric harvesting by vibrations, which in the experiments scavenged 2.32 mW.

    Emneord
    Wireless sensor network, train
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-218887 (URN)10.1049/iet-wss.2013.0048 (DOI)
    Prosjekter
    Wisenet
    Tilgjengelig fra: 2014-02-19 Laget: 2014-02-19 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    2. Reliability Experiments for Wireless Sensor Networks in Train Environment
    Åpne denne publikasjonen i ny fane eller vindu >>Reliability Experiments for Wireless Sensor Networks in Train Environment
    Vise andre…
    2009 (engelsk)Inngår i: European Microwave Week (EuMWeek), Second European Wireless Technology Conference, EuWIT, 2009, s. 37-40Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Forskningsprogram
    Elektroteknik med inriktning mot signalbehandling; Teknisk fysik med inriktning mot mikrovågsteknik
    Identifikatorer
    urn:nbn:se:uu:diva-120593 (URN)
    Konferanse
    European Microwave Week (EuMWeek), Second European Wireless Technology Conference, EuWIT
    Prosjekter
    WISENET
    Tilgjengelig fra: 2010-03-15 Laget: 2010-03-15 Sist oppdatert: 2016-04-14bibliografisk kontrollert
    3. Design of a miniaturized patch antenna for easy deployment on metal surfaces
    Åpne denne publikasjonen i ny fane eller vindu >>Design of a miniaturized patch antenna for easy deployment on metal surfaces
    2013 (engelsk)Inngår i: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 55, nr 4, s. 723-727Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A small dual-layer patch antenna designed for placement on a large conducting surface is presented. It uses the surrounding metal as a ground plane in order to reduce its size. The result is a small patch antenna with good radiation qualities in metallic surroundings. It can also be used in applications where shielding sensitive equipment from radiated fields is necessary, by using the shielding as the metal surface. It is constructed for use with the IEEE 802.15.4 standard at the 2.45 GHz ISM band. The lower layer is made in Fr-4 with standard height and width. This makes eventual serial production cheaper. The antenna has a measured total efficiency between 1.5 dB and 3.6 dB in the frequency range it is designed for. The longest side is 18.35 mm, equaling 14.9% of the wavelength.

    Emneord
    patch antennas, metallic environment, antenna measurements, compact antennas, microstrip antennas
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-197965 (URN)10.1002/mop.27437 (DOI)000315524800008 ()
    Tilgjengelig fra: 2013-04-08 Laget: 2013-04-08 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    4. Empirical Tests of Wireless Sensor Network in Jet Engine Including Characterization of Radio Wave Propagation and Fading
    Åpne denne publikasjonen i ny fane eller vindu >>Empirical Tests of Wireless Sensor Network in Jet Engine Including Characterization of Radio Wave Propagation and Fading
    2014 (engelsk)Inngår i: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 13, s. 762-765Artikkel i tidsskrift (Fagfellevurdert) Published
    Emneord
    Wireless Sensor Network, Jet engine, Propagation
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-218889 (URN)10.1109/LAWP.2014.2316311 (DOI)000335565400002 ()
    Tilgjengelig fra: 2014-02-19 Laget: 2014-02-19 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    5. Design and Evaluation of a Conformal Patch Antenna Array for use with Wireless Sensor Network inside Jet Engines
    Åpne denne publikasjonen i ny fane eller vindu >>Design and Evaluation of a Conformal Patch Antenna Array for use with Wireless Sensor Network inside Jet Engines
    2013 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-218890 (URN)
    Konferanse
    European Conference on Antennas and Propagation (EuCAP), Gothenburg.
    Tilgjengelig fra: 2014-02-19 Laget: 2014-02-19 Sist oppdatert: 2014-04-29
    6. Large Ad Hoc Shielded Room with Removable Mode Stirrer for Mobile Phone Antenna Tests
    Åpne denne publikasjonen i ny fane eller vindu >>Large Ad Hoc Shielded Room with Removable Mode Stirrer for Mobile Phone Antenna Tests
    2013 (engelsk)Inngår i: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 55, nr 1, s. 21-27Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Reverberation chambers (RC) are widely used for measuring antenna performance and parameters for MIMO systems. RCs for mobile phone antenna tests are often specially designed for this purpose. The lowest frequency of operation of an RC is decided by its size. With a trend of lower frequency bands being allocated for mobile phones, the minimum size of RCs for mobile phone antenna tests increases, and is approaching the size of a normal room. At the same time, many large shielded rooms are already in use for various electrical measurements. In this paper, a standard shielded room designed for EMC testing is used as an RC for mobile phone antenna tests. To complete the RC, a large mode stirrer is built. The fact that the room is also used for other tests requires a detachable, foldable, and lightweight stirrer design. Therefore, metal meshes are evaluated for the design of the mode stirrer. The performance of the used room is verified by standard tests for RCs, and it is verified that it is possible to measure antennas from about 400 MHz up to 4 GHz with good accuracy. The size of the room also enables measurements including humans carrying mobile phones or body area networks.

    Emneord
    Antenna measurements, electromagnetic propagation, electromagnetic shielding, microwave communication, microwave radio propagation
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-197409 (URN)10.1109/TEMC.2012.2204758 (DOI)000315118100003 ()
    Tilgjengelig fra: 2013-03-28 Laget: 2013-03-25 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    7. Sample-Selection Method for Arbitrary Fading Emulation Using Mode-Stirred Chambers
    Åpne denne publikasjonen i ny fane eller vindu >>Sample-Selection Method for Arbitrary Fading Emulation Using Mode-Stirred Chambers
    2010 (engelsk)Inngår i: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 9, s. 409-412Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Mode-stirred chambers (MSCs) consist of one or more resonant cavities coupled in some way in order to allow the measurement of different antenna parameters such as antenna efficiency, correlation, diversity gain, or multiple-input-multiple-output (MIMO) capacity, among others. In a single-cavity MSC, also known as a reverberation chamber (RC), the environment is isotropic and the amplitude of the signal is Rayleigh distributed. Real environments, however, rarely follow an isotropic Rayleigh-fading scenario. Previous results have shown that a Rician-fading emulation can be obtained via hardware modification using an RC. The different methods lack from an accurate emulation performance and are strongly dependent upon chamber size and antenna configurations. With the innate complexity of more-than-one-cavity MSC, the coupling structure generates sample sets that are complex enough so as to contain different clusters with diverse fading characteristics. This letter presents a novel method to accurately emulate a more realistic Rician-fading distribution from a Rayleigh-fading distribution by selecting parts of the sample set that forms different statistical ensembles using a complex two-cavity multi-iris-coupled MSC. Sample selection is performed using a genetic algorithm. Results demonstrate the potential of MSCs for versatile MIMO fading emulation and over-the-air (OTA) testing. The method is patent protected by EMITE Ing., Murcia, Spain.

    Emneord
    Diversity gain, mode-stirred chamber (MSC), multiple-output (MIMO) capacity
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-136546 (URN)10.1109/LAWP.2010.2049729 (DOI)000277885900003 ()
    Tilgjengelig fra: 2010-12-14 Laget: 2010-12-13 Sist oppdatert: 2017-12-11bibliografisk kontrollert
    8. Sample Selection Algorithms for Enhanced MIMO Antenna Measurements Using Mode-Stirred Reverberation Chambers
    Åpne denne publikasjonen i ny fane eller vindu >>Sample Selection Algorithms for Enhanced MIMO Antenna Measurements Using Mode-Stirred Reverberation Chambers
    Vise andre…
    2012 (engelsk)Inngår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 60, nr 8, s. 3892-3900Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Mode-stirred reverberation chambers (MSRCs) are a useful tool for measuring several wireless-related MIMO antenna parameters. In a conventional single-cavity MSRC, the emulated fading environment is isotropic and the amplitude of the signal is Rayleigh distributed. Previous contributions have enhanced the emulation capabilities of MSRCs so as to include the ability to emulate Rician- and non-isotropic fading environments. In this contribution, arbitrary amplitude probability density functions (PDF) emulation using a MSRC is presented by selecting parts of the sample set that forms different statistical ensembles. Several algorithms are presented and compared in terms of computation time and power accuracy using simulated as well as measured data from different MSRCs to obtain Rician, on-body and amplitude PDFs of standardized models. The technique is patent-protected by EMITE.

    Emneord
    Algorithms, antenna measurements, fading channels, genetic algorithms
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-182546 (URN)10.1109/TAP.2012.2201103 (DOI)000308435800037 ()
    Tilgjengelig fra: 2012-10-11 Laget: 2012-10-11 Sist oppdatert: 2017-12-07bibliografisk kontrollert
  • 34.
    Guo, Jun
    et al.
    Swiss Fed Inst Technol, Electromagnet Compatibil Grp, CH-1015 Lausanne, Switzerland.
    Rubinstein, Marcos
    Univ Appl Sci Western Switzerland, CH-2800 Yverdon, Switzerland.
    Cooray, Vernon
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Rachidi, Farhad
    Swiss Fed Inst Technol, Electromagnet Compatibil Grp, CH-1015 Lausanne, Switzerland.
    On the Modeling of Non-Vertical Risers in the Interaction of Electromagnetic Fields With Overhead Lines2019Inngår i: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 61, nr 3, s. 631-636Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper proposes a simple method to take into account non-vertical risers through an equivalent partial inductance. The proposed approach was validated considering several examples and taking as reference full-wave results obtained using a numerical electromagnetics code numerical electromagnetics code (NEC)-4.

  • 35. Guo, X
    et al.
    He, Y
    Atapattu, S
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Evans, J
    Power allocation for distributed detection systems in wireless sensor networks with limited fusion centre feedback2018Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 66, nr 10, s. 4753-4766Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider a distributed detection system for a wireless sensor network over slow-fading channels. Each sensor only has knowledge of quantized channel state information (CSI) which is received from the fusion center via a limited feedback channel. We then consider transmit power allocation at each sensor in order to maximize a J-divergence based detection metric subject to a total and individual transmit power constraints. Our aim is to jointly design the quantization regions of all sensors CSI and the corresponding power allocations. A locally optimum solution is obtained by applying the generalized Lloyd algorithm (GLA). To overcome the high computational complexity of the GLA, we then propose a low-complexity near-optimal scheme which performs very close to its GLA based counterpart. This enables us to explicitly formulate the problem and to find the unique solution despite the non-convexity of the optimization problem. An asymptotic analysis is also provided when the number of feedback bits becomes large. Numerical results illustrate that only a small amount of feedback is needed to achieve a detection performance close to the full CSI case.

  • 36.
    Guo, Xiaoxi
    et al.
    Univ Melbourne, Dept Elect & Elect Engn, Melbourne, Vic 3010, Australia..
    Leong, Alex S.
    Univ Melbourne, Dept Elect & Elect Engn, Melbourne, Vic 3010, Australia..
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Power Allocation for Estimation Outage Minimization with Secrecy Outage Constraints2016Inngår i: 2016 Australian Communications Theory Workshop (AusCTW), New York: IEEE, 2016, s. 71-76Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we investigate the distortion outage minimization problem for a wireless sensor network (WSN) in the presence of an eavesdropper. The observation signals transmitted from the sensors to the fusion center (FC) are overheard by the eavesdropper. Both the FC and the eavesdropper reconstruct minimum mean squared error (MMSE) estimates of the physical quantity observed. We address the problem of transmit power allocation to minimize the distortion outage at the FC, subject to a long-term transmit power constraint among the sensors and a secrecy outage constraint at the eavesdropper. Applying a rigorous probabilistic power allocation technique we derive power policies for the full channel state information (CSI) case. Additional suboptimal power control policies are studied for the partial CSI case in order to reduce the high computational cost as the number of sensors or receive antennas grows. Numerical results show better performance can be achieved by adding multiple receive antennas at the FC.

  • 37. Hassan, Emadeldeen
    et al.
    Noreland, Daniel
    Augustine, Robin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wadbro, Eddie
    Berggren, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Topology Optimization of Planar Antennas for Wideband Near-Field Coupling2015Inngår i: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 63, nr 9, s. 4208-4213Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present an approach to design from scratch planar microwave antennas for the purpose of ultra-wideband (UWB) near-field sensing. Up to about 120 000 design variables associated with square grids on planar substrates are subject to design, and a numerical optimization algorithm decides, after around 200 iterations, for each edge in the grid whether it should consist of metal or a dielectric. The antenna layouts produced with this approach show UWB impedance matching properties and near-field coupling coefficients that are flat over a much wider frequency range than a standard UWB antenna. The properties of the optimized antennas are successfully cross-verified with a commercial software and, for one of the designs, also validated experimentally. We demonstrate that an antenna optimized in this way shows a high sensitivity when used for near-field detection of a phantom with dielectric properties representative of muscle tissue.

  • 38. He, Yuan Yuan
    et al.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sum Rate Maximization for Cognitive MISO Broadcast Channels: Beamforming Design and Large Systems Analysis2014Inngår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 13, nr 5, s. 2383-2401Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper considers the ergodic weighted sum rate maximization (WSRMax) problem for an underlay cognitive radio multiple input single output (MISO) broadcast channel. In this setting, a secondary network, consisting of a base-station with M transmit antennas and K single-antenna secondary users (SUs), is allowed to share the same spectrum with a primary user (PU), under an average total transmit power (ATTP) constraint and an average interference power (AIP) constraint at the PU receiver. We show that the ATTP constraint always remains active, and as the maximum ATTP P-av -> infinity, the ergodic WSR approaches infinity similar to conventional non-CR networks. We propose a novel low-complexity suboptimal beamforming scheme termed "Partially-Projected & Regularized Zero-Forcing Beamforming" (PP-RZFBF) with a close-form beamformer, by combining the regularized zero-forcing (RZF) with the channel projection idea, to achieve a tradeoff between maximizing secondary throughput and suppressing secondary multiuser interference as well as the interference on PU. In order to analyze and optimize the performance of this scheme, we employ the large system analysis technique, in the limit as M and K approach infinity with a fixed ratio r = K/M. This allows us to derive deterministic limiting approximations for the PP-RZFBF problem which enables us to determine asymptotically optimal beamformers for PP-RZFBF. In the large system limit, for the PP-RZFBF scheme, we also find that as P-av -> infinity, the interference on PU caused by the secondary transmission is asymptotically removed. A special suboptimal beamforming scheme called "CZFBF" is also considered, which involves zero forcing all the interference, including the secondary multiuser interference as well as the interference imposed on PU. Various interesting comparisons between PP-RZFBF and CZFBF are provided. Numerical simulations illustrate that the asymptotically optimal beamformers for the PP-RZFBF scheme provide an excellent performance even for finite-sized systems.

  • 39.
    Hellkvist, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Performance Evaluation Of Self-Backhaul For Small-Cell 5G Solutions2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis evaluates the possibility of using millimeter waves of frequency 28GHz for the use of wireless backhaul in small cell solutions in the coming fifth generation mobile networks. This frequency band has not been used in preceding mobile networks but is undergoing a lot of research. In this thesis simulations are performed to evaluate how the high frequency waves behave inside a three dimensional grid of buildings. The simulations use highly directive antenna arrays with antenna gains of 26dBi.

    A main results of the investigation was that a high bandwidth of 800MHz was not enough to provide 12Gbps in non line-of-sight propagation within the simulations. Furthermore, without interference limiting techniques, the interference is probable to dominate the noise, even though the high diffraction losses of millimeter waves propose that interference should be very limited in urban areas.

  • 40.
    Hinnemo, Malkolm
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Design of an Antenna for a Wireless Sensor Network for Trains2011Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    An antenna for a wireless sensor network for trains is designed and built. The network will monitor temperature and vibrations of the wheel bearings on the train wagons. Doing this will allow for an earlier detection of damaged wheels, which will ease planning of maintenance and reduce wear on the rails considerably. The requirement of the system is that it is to be installed without any cables attached to the sensor nodes. This calls for wireless communication, and that for that antennas are needed.A train is a difficult environment to transmit electromagnetic (EM) waves in. It is full of metal and EM-waves cannot pass through a conducting material. Having much metal in its vicinity also affects the function of the antenna. This needs to be taken into consideration when making the design.The constructed antenna is a small dual-layer patch antenna. Dual layer means that it is constructed out of two sheets known as substrates of isolating material with different characteristics. The lower one of these substrates is made in such a way that integration with a circuit board is possible. Such integration would reduce the production cost considerably. The antenna is designed for direct placement on a conducting surface. This surface could be part of the train. It uses the surrounding metal as a ground plane in order to reduce its size. The result is a small patch antenna with good radiation qualities in metallic surroundings. The longest side is 18.35 mm, equaling 14.9 % of the wavelength that the antenna is designed for.

  • 41.
    Hinnemo, Malkolm
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Grudén, Mathias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Design of a Miniaturized Patch Antenna for Easy Deployment on Metal Surfaces2012Konferansepaper (Fagfellevurdert)
  • 42.
    Hinnemo, Malkolm
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Zherde, Filip
    Edling, Thomas
    Edvinsson, Nils
    Grudén, Mathias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Brunnberg, Kjell
    Jansson, Erik
    Hellström, Ulf
    Andersson, Lennart
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Continuous Monitoring of Train Wagons Using Wireless Sensor Network and Battery Assisted RFID Tags2012Inngår i: GigaHertz 2012 conference, Stockholm, Sweden, 2012., 2012Konferansepaper (Fagfellevurdert)
  • 43.
    Holmberg, Måns
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Dancila, Dragos
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Hjörvarsson, Björgvin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Marattukalam, Jithin J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Johansson, Niklas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Andersson, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Direct metal laser sintering printed millimeter and submillimeter waveguides2018Konferansepaper (Annet vitenskapelig)
  • 44.
    Ingvarsson, Staffan
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Historiska institutionen.
    Telefonkriget i Stockholm: Nationella och lokala perspektiv 1903-19182016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This is a study that focuses on the debate and the different arguments that was used in the period 1903-1918 during the time when the monopoly concerning telephones where established in Stockholm and Sweden and when Stockholm had different competing telephone companies. The different arguments used both in the Swedish parliament and in the Stockholm City Council pro and against the creation of a national monopoly are studied. The purpose of the study is to describe how the debate evolved and how the different arguments where used. The primary arguments against the creation of a monopoly where mostly the same during the studied time; an ideological argumentation based on the positive effects of competition and the argument that the cost for the state to buy the competitor was too high. The argument for creation of the monopoly evolved during time. In the beginning the main argument was based on theory of natural monopolies but over time arguments based on the socialist position that state monopolies where good gained ground and in the end of the studied period the fact that the state lost earnings on the competition also became a valid argument for the creation of the monopoly. The shortages concerning vital materials because of the war were also used as arguments in the end of the studied period. The debate evolves during a time in which the Swedish parliamentary system also evolves and universal suffrages is introduced and the final decision in creating the monopoly by granting the national operator finances for acquiring the private company is in part due to the fact of the by then different political situation in the Swedish parliament. The local dimension in this study shows a difference between the national and the local perspective where – the ideological dimensions apart – the city had fiscal and influenced based reasons to prefer the city based private company before the state owned national operator.

  • 45.
    Jobs, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Design and Performance of Diversity based Wireless Interfaces for Sensor Network Nodes2013Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The main focus of the work presented in this licentiate thesis concerns antenna design, adaptive antenna control and investigation on how the performance of small wireless nodes can be increased by inclusion of multiple antennas. In order to provide an end-user suitable solution for wireless nodes the devices require both small form factor and good performance in order to be competitive on the marked and thus the main part of this thesis focuses on techniques developed to achieve these goals. Two prototype systems have been developed where one has been used by National Defence Research Agency (FOI) to successfully monitor a test-subject moving in an outdoor terrain. The other prototype system shows the overall performance gain achievable in a wireless sensor node when multiple antennas and antenna beam steering is used. As an example of how to include multiple antennas in a wireless node the concept of using dual conformal patch antennas for wireless nodes is presented. The proposed antenna showed an excess of 10 dB gain when using a single driven antenna element as would be the case in a system utilizing antenna selection combining. When used as a 2-element phased array, up to 19 dB gain was obtained in a multiscattering environment. Using the second order resonance the proposed antenna structure achieves low mutual coupling and a reflection coefficient lower than -15 dB. The presented antenna design shows how a dual antenna wireless node can be designed using discrete phase control with passive matching which provides a good adaptive antenna solution usable for wireless sensor networks. The inclusion of discrete phase sweep diversity in a wireless node has been evaluated and shown to provide a significant diversity gain. The diversity gain of a discrete phase sweep diversity based system was measured in both a reverberation chamber and a real life office environment. The former environment showed between 5.5 to 10.3 dB diversity gain depending on the detector architecture and the latter showed a diversity gain ranging from 1 to 5.4 dB. Also the performance of nodes designed to be placed in a high temperature and multiscattering environment (the fan stage of a jet engine) has been evaluated. The work was carried out in order to verify that a wireless sensor network is able to operate in such a multiscattering environment. It was shown that the wireless nodes are able to operate in an emulated turbine environment based on real-life measured turbine fading data. The tested sensor network was able to transmit 32 byte packages using cyclic redundancy check at 2 Mbps at an engine speed of 13.000 rpm.

    Delarbeid
    1. Conformal dual patch antenna for diversity based sensor nodes
    Åpne denne publikasjonen i ny fane eller vindu >>Conformal dual patch antenna for diversity based sensor nodes
    2012 (engelsk)Inngår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 48, nr 6, s. 306-307Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A conformal antenna structure based on dual triangular patches is presented. The dual antennas are designed to be used in diversity based sensor node applications and are integrated in the enclosure of the node. The internal shielded enclosure houses the required electronics and power supply. Simulations and measurements show acceptable diversity performance and efficiency in the second resonance mode.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrovågsteknik; Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-172827 (URN)10.1049/el.2012.0088 (DOI)000301439000005 ()
    Prosjekter
    WISENET
    Forskningsfinansiär
    Vinnova, WISENET
    Tilgjengelig fra: 2012-04-17 Laget: 2012-04-16 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    2. Diversity Techniques for Robustness and Power Awareness in Wireless Sensor Systems for Railroad Transport Applications
    Åpne denne publikasjonen i ny fane eller vindu >>Diversity Techniques for Robustness and Power Awareness in Wireless Sensor Systems for Railroad Transport Applications
    2011 (engelsk)Inngår i: Sustainable Wireless Sensor Networks / [ed] Winston Seah and Yen Kheng Tan, InTech Open Publishers , 2011, 1, s. 75-95Kapittel i bok, del av antologi (Fagfellevurdert)
    sted, utgiver, år, opplag, sider
    InTech Open Publishers, 2011 Opplag: 1
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-159204 (URN)978-953-307-297-5 (ISBN)
    Prosjekter
    wisenet
    Tilgjengelig fra: 2011-09-25 Laget: 2011-09-25 Sist oppdatert: 2016-04-20bibliografisk kontrollert
    3. Antenna diversity with opportunistic combining for ASk systems with single channel receivers
    Åpne denne publikasjonen i ny fane eller vindu >>Antenna diversity with opportunistic combining for ASk systems with single channel receivers
    2010 (engelsk)Inngår i: Proceedings of the Fourth European Conference on Antennas and Propagation (EuCAP), 2010, s. 1-5Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-138838 (URN)
    Konferanse
    Fourth European Conference on Antennas and Propagation (EuCAP)
    Prosjekter
    WISENET
    Tilgjengelig fra: 2010-12-20 Laget: 2010-12-20 Sist oppdatert: 2016-04-18bibliografisk kontrollert
    4. Performance Evaluation of a Conformal Dual Patch Antenna in an Indoor Environment
    Åpne denne publikasjonen i ny fane eller vindu >>Performance Evaluation of a Conformal Dual Patch Antenna in an Indoor Environment
    2013 (engelsk)Inngår i: 7th European Conference on Antennas and Propagation (EuCAP), 2013, s. 439-442Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    The performance of a conformal dual patch antenna design for wireless sensor networks were measured and evaluated in a real world multi-scattering environment. Both simulated and measured radiation patterns when using the antenna as a two element phased array were measured and corresponded well. The environment was measured and show strong fading characteristics. The measured data shows that the proposed structure gives a distinct advantage to the nodes communication compared to single element antennas while keeping the form factor suitable for integration of embedded hardware.

    Serie
    Proceedings of the European Conference on Antennas and Propagation, ISSN 2164-3342
    Emneord
    Antenna, Array, Reconfigurable, Conformal, Sensor, WSN, Indoor, Steerable, Performance
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrovågsteknik
    Identifikatorer
    urn:nbn:se:uu:diva-198643 (URN)000327126000100 ()978-88-907018-3-2 (ISBN)
    Konferanse
    7th European Conference on Antennas and Propagation (EuCAP), APR 08-12, 2013, Gothenburg, SWEDEN
    Prosjekter
    WISENET
    Tilgjengelig fra: 2013-04-22 Laget: 2013-04-22 Sist oppdatert: 2015-03-09bibliografisk kontrollert
    5. Wireless sensor networks for aircraft engines
    Åpne denne publikasjonen i ny fane eller vindu >>Wireless sensor networks for aircraft engines
    Vise andre…
    2011 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-138847 (URN)
    Konferanse
    Smart Systems Integration Conference, Dresden, Germany, 22-23.03.2011
    Prosjekter
    wisenet
    Tilgjengelig fra: 2010-12-20 Laget: 2010-12-20 Sist oppdatert: 2016-04-20bibliografisk kontrollert
    6. Wireless body area network (WBAN) monitoring application system (MASS) for personal monitoring
    Åpne denne publikasjonen i ny fane eller vindu >>Wireless body area network (WBAN) monitoring application system (MASS) for personal monitoring
    Vise andre…
    2009 (engelsk)Inngår i: 6th edition of the International Workshop on Wearable Micro and Nano Technologies for Personalised Health (pHealth 2009), Oslo, Norge, 2009Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrovågsteknik
    Identifikatorer
    urn:nbn:se:uu:diva-121065 (URN)
    Konferanse
    6th edition of the International Workshop on Wearable Micro and Nano Technologies for Personalised Health (pHealth 2009), Oslo, Norge
    Prosjekter
    WISENET
    Tilgjengelig fra: 2010-03-18 Laget: 2010-03-18 Sist oppdatert: 2016-04-14bibliografisk kontrollert
  • 46.
    Jobs, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Wireless Interface Technologies for Sensor Networks2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The main focus of the work presented in this thesis concerns the development and improvement of Wireless Sensor Networks (WSNs) as well as Wireless Body Area Networks (WBANs). WSN consist of interlinked, wireless devices (nodes) capable of relaying data wirelessly between the nodes. The applications of WSNs are very broad and cover both wireless fitness monitoring systems such as pulse watches or wireless temperature monitoring of buildings, among others.

    The topics investigated in the work presented within this thesis covers antenna design, wireless propagation environment evaluation and modeling, adaptive antenna control and wireless nodes system design and evaluation. In order to provide an end-user suitable solution for wireless nodes the devices require both small form factor and good performance in order to be competitive on the marked and thus the main part of this thesis focuses on techniques developed and data collected to help achieve these goals. 

    Several different prototype systems have been developed which have been used to measure data by the Swedish Defence Research Agency (FOI), GKN Aerospace Sweden AB, the Swedish Transport Administration. The system developed with GKN Aerospace was used to do real-time test measurements inside a running RM12 jet engine and required a substantial amount of measurements, environmental modeling and system validation in order to properly design a wireless system suitable for the harsh and fast fading environment inside a jet engine. For FOI improvements were made on a wearable wireless body area network initially developed during the authors master thesis work. Refinements included work on new generation wireless nodes, antenna packaging and node-supported diversity techniques.

    Work and papers regarding the design of different types of antennas suitable for wireless nodes are presented. The primary constraints on the presented antennas are the limited electrical size. The types of antennas developed include electrically small helix antennas manufactured both on stretchable substrates consisting of a PDMS substrate with Galinstan as the liquid metal conductors, screen printed silver ink for helix antennas and conformal dual patch antennas for wireless sensor nodes. Other standard type antennas are included on the wireless sensors as well.

    Delarbeid
    1. A Tunable Spherical Cap Microfluidic Electrically Small Antenna
    Åpne denne publikasjonen i ny fane eller vindu >>A Tunable Spherical Cap Microfluidic Electrically Small Antenna
    2013 (engelsk)Inngår i: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 9, nr 19, s. 3230-3234Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We present a novel microfluidic three-dimensional elec- trically small antenna (ESA). It is easy to construct simply by pneumatically inflating a planar stretchable liquid alloy microfluidic antenna into a spherical cap. Its center frequency is tuned when it is inflated; demonstrating combined high efficiency and a wide tunable frequency range around its hemispherical shape.

    sted, utgiver, år, opplag, sider
    Weinheim: John Wiley & Sons, 2013
    Emneord
    microfluidic electronics
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot materialvetenskap; Teknisk fysik med inriktning mot mikrosystemteknik; Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-198541 (URN)10.1002/smll.201300070 (DOI)000327899900007 ()
    Prosjekter
    VR Forass to Wu, and Wisenet
    Tilgjengelig fra: 2013-04-19 Laget: 2013-04-19 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    2. Antenna diversity with opportunistic combining for ASk systems with single channel receivers
    Åpne denne publikasjonen i ny fane eller vindu >>Antenna diversity with opportunistic combining for ASk systems with single channel receivers
    2010 (engelsk)Inngår i: Proceedings of the Fourth European Conference on Antennas and Propagation (EuCAP), 2010, s. 1-5Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-138838 (URN)
    Konferanse
    Fourth European Conference on Antennas and Propagation (EuCAP)
    Prosjekter
    WISENET
    Tilgjengelig fra: 2010-12-20 Laget: 2010-12-20 Sist oppdatert: 2016-04-18bibliografisk kontrollert
    3. Empirical Tests of Wireless Sensor Network in Jet Engine Including Characterization of Radio Wave Propagation and Fading
    Åpne denne publikasjonen i ny fane eller vindu >>Empirical Tests of Wireless Sensor Network in Jet Engine Including Characterization of Radio Wave Propagation and Fading
    2014 (engelsk)Inngår i: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 13, s. 762-765Artikkel i tidsskrift (Fagfellevurdert) Published
    Emneord
    Wireless Sensor Network, Jet engine, Propagation
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-218889 (URN)10.1109/LAWP.2014.2316311 (DOI)000335565400002 ()
    Tilgjengelig fra: 2014-02-19 Laget: 2014-02-19 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    4. Modelling of EM Propagation in Simplified Jet Turbine Structure using Helical Rays
    Åpne denne publikasjonen i ny fane eller vindu >>Modelling of EM Propagation in Simplified Jet Turbine Structure using Helical Rays
    2015 (engelsk)Inngår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 51, nr 11, s. 809-811Artikkel i tidsskrift, Letter (Fagfellevurdert) Published
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-239397 (URN)10.1049/el.2014.4465 (DOI)000354773500005 ()
    Tilgjengelig fra: 2014-12-22 Laget: 2014-12-22 Sist oppdatert: 2017-12-05bibliografisk kontrollert
    5. Hemispherical coil electrically small antenna made by stretchable conductors printing and plastic thermoforming
    Åpne denne publikasjonen i ny fane eller vindu >>Hemispherical coil electrically small antenna made by stretchable conductors printing and plastic thermoforming
    2015 (engelsk)Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, nr 2, artikkel-id 027004Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A production scalable technique is presented to make hemispherical coil antennas by using a stretchable printed silver paste conductor and plastic thermoforming. To ease the fabrication process an unbalanced feed-structure was designed for solderless mounting on conductive materials. The manufactured antenna had a resonance frequency of 2.467 GHz with a reflection coefficient of -33.8 dB. The measured and simulated radiation patterns corresponded to that of monopole structure and the measured efficiency was 40%.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik; Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-238904 (URN)10.1088/0960-1317/25/2/027004 (DOI)000349106800024 ()
    Tilgjengelig fra: 2014-12-17 Laget: 2014-12-17 Sist oppdatert: 2017-12-05bibliografisk kontrollert
    6. Measurements and Simulations of Wave Propagation for Wireless Sensor Networks in Jet Engine Turbines
    Åpne denne publikasjonen i ny fane eller vindu >>Measurements and Simulations of Wave Propagation for Wireless Sensor Networks in Jet Engine Turbines
    2011 (engelsk)Inngår i: IEEE Antennas and Wireless Propagation Letters, ISSN 1536-1225, E-ISSN 1548-5757, Vol. 10, s. 1139-1142Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    In this letter, measurements and simulations of wave propagation inside a jet engine fan have been performed. The investigation was done using both EM simulations of different cases of propagation inside the engine and by measuring the corresponding cases inside a half-scale model of a jet engine fan. The average path loss was calculated, and the shapes of the fading distributions were extracted. The time between two consecutive fading dips was measured in the empirical part. Measurements were performed with engine speeds of both 30 and 60 rpm and were shown to be linearly scalable from 60 rpm to full speed of 10 000 rpm. The results showed an average path loss of about 55 dB. When scaling the measurements from 60 rpm to full-speed rotation of about 10 000 rpm, the fading was so severe that the time slot between consecutive fading dips was limited to 290 mu s.

    Emneord
    Communication channels, electromagnetic propagation, propagation losses, radio communication, radiowave propagation
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-161778 (URN)10.1109/LAWP.2011.2171309 (DOI)000296260200004 ()
    Tilgjengelig fra: 2011-11-21 Laget: 2011-11-17 Sist oppdatert: 2017-12-08bibliografisk kontrollert
    7. Conformal dual patch antenna for diversity based sensor nodes
    Åpne denne publikasjonen i ny fane eller vindu >>Conformal dual patch antenna for diversity based sensor nodes
    2012 (engelsk)Inngår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 48, nr 6, s. 306-307Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A conformal antenna structure based on dual triangular patches is presented. The dual antennas are designed to be used in diversity based sensor node applications and are integrated in the enclosure of the node. The internal shielded enclosure houses the required electronics and power supply. Simulations and measurements show acceptable diversity performance and efficiency in the second resonance mode.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrovågsteknik; Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-172827 (URN)10.1049/el.2012.0088 (DOI)000301439000005 ()
    Prosjekter
    WISENET
    Forskningsfinansiär
    Vinnova, WISENET
    Tilgjengelig fra: 2012-04-17 Laget: 2012-04-16 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    8. Performance Evaluation of a Conformal Dual Patch Antenna in an Indoor Environment
    Åpne denne publikasjonen i ny fane eller vindu >>Performance Evaluation of a Conformal Dual Patch Antenna in an Indoor Environment
    2013 (engelsk)Inngår i: 7th European Conference on Antennas and Propagation (EuCAP), 2013, s. 439-442Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    The performance of a conformal dual patch antenna design for wireless sensor networks were measured and evaluated in a real world multi-scattering environment. Both simulated and measured radiation patterns when using the antenna as a two element phased array were measured and corresponded well. The environment was measured and show strong fading characteristics. The measured data shows that the proposed structure gives a distinct advantage to the nodes communication compared to single element antennas while keeping the form factor suitable for integration of embedded hardware.

    Serie
    Proceedings of the European Conference on Antennas and Propagation, ISSN 2164-3342
    Emneord
    Antenna, Array, Reconfigurable, Conformal, Sensor, WSN, Indoor, Steerable, Performance
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrovågsteknik
    Identifikatorer
    urn:nbn:se:uu:diva-198643 (URN)000327126000100 ()978-88-907018-3-2 (ISBN)
    Konferanse
    7th European Conference on Antennas and Propagation (EuCAP), APR 08-12, 2013, Gothenburg, SWEDEN
    Prosjekter
    WISENET
    Tilgjengelig fra: 2013-04-22 Laget: 2013-04-22 Sist oppdatert: 2015-03-09bibliografisk kontrollert
    9. Diversity Techniques for Robustness and Power Awareness in Wireless Sensor Systems for Railroad Transport Applications
    Åpne denne publikasjonen i ny fane eller vindu >>Diversity Techniques for Robustness and Power Awareness in Wireless Sensor Systems for Railroad Transport Applications
    2011 (engelsk)Inngår i: Sustainable Wireless Sensor Networks / [ed] Winston Seah and Yen Kheng Tan, InTech Open Publishers , 2011, 1, s. 75-95Kapittel i bok, del av antologi (Fagfellevurdert)
    sted, utgiver, år, opplag, sider
    InTech Open Publishers, 2011 Opplag: 1
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-159204 (URN)978-953-307-297-5 (ISBN)
    Prosjekter
    wisenet
    Tilgjengelig fra: 2011-09-25 Laget: 2011-09-25 Sist oppdatert: 2016-04-20bibliografisk kontrollert
    10. Wireless body area network (WBAN) monitoring application system (MASS) for personal monitoring
    Åpne denne publikasjonen i ny fane eller vindu >>Wireless body area network (WBAN) monitoring application system (MASS) for personal monitoring
    Vise andre…
    2009 (engelsk)Inngår i: 6th edition of the International Workshop on Wearable Micro and Nano Technologies for Personalised Health (pHealth 2009), Oslo, Norge, 2009Konferansepaper, Publicerat paper (Fagfellevurdert)
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrovågsteknik
    Identifikatorer
    urn:nbn:se:uu:diva-121065 (URN)
    Konferanse
    6th edition of the International Workshop on Wearable Micro and Nano Technologies for Personalised Health (pHealth 2009), Oslo, Norge
    Prosjekter
    WISENET
    Tilgjengelig fra: 2010-03-18 Laget: 2010-03-18 Sist oppdatert: 2016-04-14bibliografisk kontrollert
  • 47.
    Jobs, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Grudén, Mathias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Rydberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Modelling of EM Propagation in Simplified Jet Turbine Structure using Helical Rays2015Inngår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 51, nr 11, s. 809-811Artikkel i tidsskrift (Fagfellevurdert)
  • 48.
    Kathiravelu, Thabotharan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Pears, Arnold
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    State of the art in modeling opportunistic networks2011Inngår i: Mobile Opportunistic Networks: Architectures, Protocols and Applications, Boca Raton, FL: Auerbach Publications , 2011, s. 25-50Kapittel i bok, del av antologi (Fagfellevurdert)
  • 49.
    Krasowski, Piotr
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Troha, Douglas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Wireless system design: NB-IoT downlink simulator2017Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The newly defined NB-IoT standard currently lacks a toolkit and simulator. In order to develop algorithms for this new standard there is a need for channels and signals as reference during tests. MATLAB is commonly used for testing LTE signals and therefore the toolkit was developed in this environment. The toolkit focuses primarily on the Layer 1-relevant functionality of NB-IoT, the grid generation, encoding, rate-matching and modulation of channels. The simulator focuses on testing the developed toolkit in a virtual LTE NB-IoT environment. The virtual environment attempts to emulate a base station and a terminal. The path followed is scheduling, channel processing, grid generation, QPSK and OFDM modulation through a modeled channel, OFDM demodulation, channel estimation, equalisation, QPSK demodulation and reversal of channel processing. The simulator tests primarily the NPDSCH channel implementations. Measurements of bit error and block error rates were made and it was concluded that they follow the expected trends. More testing is required to validate the remaining channels. A sector equaliser and an interpolating equaliser were tested by measuring block error rate and checking constellation diagrams and it was concluded that the performance of the interpolation equaliser is more consistent. In order to improve the equalisation further the noise estimation must be reworked.

  • 50.
    Lei, Lei
    et al.
    Luxembourg Univ, Interdisciplinary Ctr Secur Reliabil & Trust, Luxembourg, Luxembourg.
    You, Lei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Yang, Yang
    Luxembourg Univ, Interdisciplinary Ctr Secur Reliabil & Trust, Luxembourg, Luxembourg.
    Yuan, Di
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datalogi.
    Chatzinotas, Symeon
    Luxembourg Univ, Interdisciplinary Ctr Secur Reliabil & Trust, Luxembourg, Luxembourg.
    Ottersten, Bjorn
    Luxembourg Univ, Interdisciplinary Ctr Secur Reliabil & Trust, Luxembourg, Luxembourg.
    Power and Load Optimization in Interference-Coupled Non-Orthogonal Multiple Access Networks2018Inngår i: 2018 IEEE Global Communications Conference (GLOBECOM), IEEE , 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Towards energy savings in large-scale non-orthogonal multiple access (NOMA) networks, we investigate power and load optimization for multi-cell and multi-carrier NOMA systems in this paper. To capture the coupling relation of mutual interference among cells, firstly, we extend a load-coupling model from orthogonal multiple access (OMA) to NOMA networks. Next, with this analytical tool, we formulate the considered optimization problem in NOMA-based load-coupled systems, where optimizing load, power, and determining decoding order are the key aspects in the optimization. Theoretically, we prove that the minimum network energy consumption can be achieved by using all the time-frequency resources in each cell to deliver users' demand. To achieve the optimal load and enable efficient power optimization, we develop a power-adjustment algorithm. Numerical results demonstrate promising energy-saving gains of NOMA over OMA in large-scale cellular networks, in particular for the high-demand and resource-limited scenarios.

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