Change search
Refine search result
12 1 - 50 of 77
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Arenas, Julia Martinez
    et al.
    Ecole National Superieure de Telecommunications, Site de Toulouse.
    Landström, Daniel
    Department of Electrosciences, Lund Institute of Technology, Luleå tekniska universitet, Department of Applied Electronics, Lund University.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Börjesson, Per Ola
    Lund Institute of Technology, Department of Applied Electronics.
    Boucheret, Marie-Laure
    Ecole Nationale Supérieure des Télécommunications.
    Ödling, Per
    Department of Electrosciences, Lund Institute of Technology.
    Synchronization in OFDM systems: Sensitivity to the choice of pulse shape1997Conference paper (Refereed)
  • 2.
    Atanasovski, Vladimir M.
    et al.
    Faculty of Electrical Engineering, Ss. Cyril and Mehtodius, Skopje.
    Beek, Jaap van de
    Dejonghe, Antoine
    Interuniversity Micro-Electronics Center (IMEC), Leuven.
    Denkovski, Daniel
    Faculty of Electrical Engineering, Ss. Cyril and Mehtodius, Skopje.
    Gravilovska, Liljana M.
    Faculty of Electrical Engineering, Ss. Cyril and Mehtodius, Skopje.
    Grimoud, Sébastien
    Orange Labs, Telecom R and D, Issy-les-Moulineaux.
    Mähönen, Petri H.
    Institute for Networked Systems, RWTH Aachen University.
    Pavloski, Mihajlo
    Faculty of Electrical Engineering, Ss. Cyril and Mehtodius, Skopje.
    Rakovic, Valentin
    Faculty of Electrical Engineering, Ss. Cyril and Mehtodius, Skopje.
    Rihijärvi, Janne
    Institute for Networked Systems, RWTH Aachen University.
    Sayraç, Berna
    Orange Labs., Issy-les-Moulineaux.
    Constructing radio environment maps with heterogeneous spectrum sensors2011In: 2011 IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN 2011): Aachen, Germany, 3 - 6 May, 2011, Piscataway, NJ: IEEE Communications Society, 2011, 660-661 p., 5936266Conference paper (Refereed)
    Abstract [en]

    In this demonstration proposal we describe a prototype of a radio environment map (REM) for storing and reasoning about spectrum data obtained from heterogeneous sources. The architecture of the REM prototype is both modular and extendible, and can be used with very diverse spectrum sensors, ranging from high-fidelity spectrum analyzers to dedicated low-cost embedded solutions. In the proposed demonstration we will illustrate how information such as transmitter locations and estimates of spectrum occupancy over space and time can be inferred and made available through the REM, based on information obtained from a network of different spectrum sensors deployed specifically for the demonstration

  • 3.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Channel quality feedback schemes for 3GPP's Evolved-UTRA downlink2006In: IEEE GLOBECOM 2006: 2006 Global Telecommunications Conference; San Francisco, CA, USA, 27 November - 1 December 2006, Piscataway, NJ: IEEE Communications Society, 2006, 4151293Conference paper (Refereed)
    Abstract [en]

    Today's packet-based cellular systems typically are equipped with a channel quality reporting mechanism that supports scheduling and adaptive modulation/coding. When resources are scheduled not only In time but also In frequency the design of the return channel becomes intricate. The feedback signalling must balance improved cell-throughput with deteriorated spectral efficiency In the return link due to excessive signalling. In this contribution we examine system simulation results for the downlink of 3GPP's long-term evolution system equipped with various signalling schemes. The simulations results show that for a certain uplink load In bits/s/Hz, emphasizing the quality of the mobile's best channel instants (assigning these with more signalling bits) provides about 12% higher downlink throughput than capturing the quality of all channel Instants equally well. Moreover, about 95% of the throughput provided by an ideal reference feedback scheme Is obtained.

  • 4.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Estimation of synchronization parameters1996Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with the estimation of synchronization parameters in {Orthogonal Frequency Division Multiplexing} (OFDM) communication systems and in active ultrasonic measuring systems. Estimation methods for the timing and frequency offset and for the attenuation taps of the frequency selective channel are presented and investigated.In OFDM communication systems the estimation of the timing offset of the transmitted data frame is one important parameter. This offset provides the receiver with a means of synchronizing its sampling clock to that of the transmitter. A second important parameter is the offset in the carrier frequency used by the receiver to demodulate the received signal.For OFDM systems using a cyclic prefix, the joint {Maximum Likelihood} (ML) estimation of the timing and carrier frequency offset is introduced. The redundancy introduced by the prefix is exploited optimally. This novel method is derived for a non-dispersive channel. Its performance, however, is also evaluated for a frequency-selective Rayleigh-fading radio channel. Time dispersion causes an irreducible error floor in this estimator's performance. This error floor is the limiting factor for the applicability of the timing estimator. Depending on the requirements, it may be used in either an acquisition or a tracking mode. For the frequency estimator the error floor is low enough to allow for stable frequency tracking.A low-complex variant of the timing offset estimator is presented allowing a simple implementation. This is the ML estimator, given a 2-bit representation of the received signal as the sufficient statistics. Its performance is evaluated for a frequency-selective Rayleigh-fading radio channel and for a twisted-pair copper channel. Simulations show this estimator to have a similar error floor as the full resolution ML estimator.The problem of estimating the propagation time of a signal is also of interest in active pulse echo systems, such as are used in, {\it e.g.}, radar, medical imaging, and geophysics. The {Minimum Mean Squared Error} (MMSE) estimator of arrival time is derived and investigated for an active airborne ultrasound measurement system. Besides performing better than the conventional {\it Maximum a Posteriori} (MAP) estimator, this method can be used to develop different estimators in situations where the system Signal to Noise Ratio (SNR) is unknown.Coherent multi-amplitude OFDM receivers generally need to compensate for a frequency selective channel in order to detect transmitted data symbols reliably. For this purpose, a channel equalizer needs to be fed estimates of the subchannel attenuations.The linear MMSE estimator of these attenuations is presented. Of all linear estimators, this estimator optimally makes use of the frequency correlation between the subchannel attenuations. Low-complex modified estimators are proposed and investigated. The proposed modifications cause an irreducible error floor for this estimator's performance, but simulations show that for SNR values up to 20~dB, the improvement of a modified estimator compared to the Least Squares (LS) estimator is at least 3~dB.

  • 5.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    OFDM Spectral Precoding with Protected Subcarriers2013In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 17, no 12, 2209-2212 p.Article in journal (Refereed)
    Abstract [en]

    A new precoder structure reduces an OFDM signal's out-of-band emission by tens of decibels while allowing a receiver to employ a classical OFDM channel estimator.

  • 6. Beek, Jaap van de
    Orthogonal multiplexing in a subspace of frequency well-localized signals2010In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 14, no 10, 882-884 p., 5558995Article in journal (Refereed)
    Abstract [en]

    multiplexing scheme onto K OFDM subcarriers arranges M ≤ K dimensions to shape the signal's transmit spectrum while the remaining K - M dimensions are used to orthogonally multiplex data symbols. This results in a new class of basis functions along with an equivalent precoder structure. In particular, N-continuous OFDM signals are realized as an orthogonal multiplex

  • 7. Beek, Jaap van de
    Sculpting the multicarrier spectrum: a novel projection precoder2009In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 13, no 12, 881-883 p.Article in journal (Refereed)
    Abstract [en]

    A novel spectrum-sculpting precoder flexibly suppresses emitted power in predefined parts of the spectrum by tens of decibels. The precoder is particularly suitable in cognitive OFDM systems where the emitted signal's spectrum is adapted to time-varying reigning radio circumstances

  • 8.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Synchronization and channel estimation in OFDM systems1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis addresses synchronization and channel estimation in OFDM communication systems. The joint maximum likliehood estimator of symbol time and carrier frequency offsets for OFDM systems using a cyclic prefix is presented. This estimator exploits the redundancy introduced by the prefix and does not require extra pilot information. Signal models, accounting for pulse shaping, channel dispersion, or slowly changing synchronization errors and the associated maximum likliehood estimators are presented. Tracking synchronization of a multiuser OFDM system, which often has been questioned, is feasible using a scheme incorporating the above estimator concept. Furthermore, this thesis analyzes channel estimators based on the discrete Fourier transform. The symbol error rate of systems employing these estimators may experience an irreducible error floor. A novel channel estimation concept using singular-value decomposition of the channel attenuations is presented. These channel estimators, designed with suitably chosen fixed design parameters, combine low-complexity and high performance.

  • 9.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    White Paper for Research Beyond 5G2015Report (Other academic)
  • 10.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Berggren, Fredrik
    Huawei Technologies Sweden.
    EVM-constrained OFDM precoding for reduction of out-of-band emission2009In: 2009 IEEE 70th Vehicular Technology Conference - Fall: VTC 2009-Fall; Anchorage, Alaska, USA, 20 - 23 September 2009, Piscataway, NJ: IEEE Communications Society, 2009, 5378740Conference paper (Refereed)
    Abstract [en]

    This contribution addresses the potential of N-continuous OFDM signals in systems where the receiver is unaware of the transmitter precoder operation. First, we present a memoryless precoder rendering N-continuous signals. Second, we evaluate the effect on the magnitude of the emitted signal's error-vector. Third, we present three ad hoc precoders designed under a hard constraint on the allowed EVM still significantly suppressing out-of-band power

  • 11. Beek, Jaap van de
    et al.
    Berggren, Fredrik
    Huawei Technologies Sweden.
    N-continuous OFDM2009In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 13, no 1, 1-3 p.Article in journal (Refereed)
    Abstract [en]

    In this letter we report a new OFDM signalling format characterized by a precoder that renders the emitted signal's phase and amplitude continuous. It achieves superior outof- band power characteristics at the price of a slightly reduced receiver sensitivity

  • 12. Beek, Jaap van de
    et al.
    Berggren, Fredrik
    Huawei Technologies Sweden.
    Out-of-band power suppression in OFDM2008In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 12, no 9Article in journal (Refereed)
    Abstract [en]

    In this letter we show that judicious modulation of non-data subcarriers renders a transmitted OFDM signal and a few of its higher-order derivatives continuous at the OFDM symbol boundaries. This novel approach results in reduced out-of-band emission: typically, it achieves over 30 dB power suppression at adjacent-channel center-frequencies

  • 13.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Bollen, Math
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Larsson, Anders
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Eriksson, Mats
    Arctos Labs Scandinavia AB.
    Can Solar Power Help Providing Broadband Cellular Coverage in Extreme-Rural Sweden?2016Report (Other academic)
  • 14.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Börjesson, Per Ola
    Luleå tekniska universitet, Lund Institute of Technology, Department of Applied Electronics.
    Boucheret, Marie-Laure
    Ecole Nationale Supérieure des Télécommunications.
    Arenas, Julia Martinez
    Ecole National Superieure de Telecommunications, Site de Toulouse, Ericsson Radio Systems AB.
    Landström, Daniel
    Department of Electrosciences, Lund Institute of Technology, Luleå tekniska universitet, Department of Applied Electronics, Lund University.
    Ödling, Per
    Luleå tekniska universitet.
    Östberg, Christer
    Ericsson Mobile Communication AB, Telia Research AB, Telia Research.
    Wahlqvist, Mattias
    Telia Research AB, Luleå tekniska universitet.
    Wilson, Sarah Kate
    Luleå tekniska universitet, ArrayComm, San Jose.
    A time and frequency synchronization scheme for multiuser OFDM1998Report (Refereed)
  • 15.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Börjesson, Per Ola
    Lunds universitet.
    Boucheret, Marie-Laure
    Landström, Daniel
    Arenas, Julia Martiez
    Ödling, Per
    Östberg, Christer
    Wahlqvist, Mattias
    Wilson, Sarah Kate
    Luleå tekniska universitet.
    A time and frequency synchronization scheme for multiuser OFDM1999In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 17, no 11, 1900-1914 p.Article in journal (Refereed)
    Abstract [en]

    We present a multiuser synchronization scheme for tracking the mobile's uplink time and frequency offsets. It uses the redundancy introduced by the cyclic prefix and does not need additional pilots. We show performance results of an orthogonal frequency division multiplexing (OFDM)-based radio interface based on universal mobile telecommunication system (UMTS) parameters. For a UMTS-typical mobile channel environment, the performance of a coherent system employing the scheme is virtually indistinguishable from the performance of a perfectly synchronized system. In a differentially modulated system, synchronization errors decrease the system performance by about 0.7 dB compared to a perfectly synchronized system. Index Terms - Communication system, delay estimation, frequency estimation, multicarrier, multiuser system, orthogonal frequency division multiplexing (OFDM), synchronization, universal mobile telecommunication system (UMTS).

  • 16.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    Boucheret, Marie-Laure
    Landström, Daniel
    Luleå tekniska universitet.
    Arenas, Julia Martinez
    Ödling, Per
    Luleå tekniska universitet.
    On synchronization in an OFDM based UMTS proposal1997In: Emerging techniques for communication terminals: proceedings of COST 254 Workshop, Toulouse, France, 07-09 July 1997., Toulouse: INP-ENSEEIHT , 1997, 315-320 p.Conference paper (Other academic)
    Abstract [en]

    In this paper we discuss three signal models and respective Maximum Likelihood estimators of time and frequency osets. We consider implementation structures for these estimators. Furthermore, we discuss the applicability of these estimators and some variants in a proposal for the future UMTS.

  • 17.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    Boucheret, Marie-Laure
    Landström, Daniel
    Luleå tekniska universitet.
    Arenas, Julia Martinez
    Ödling, Per
    Luleå tekniska universitet.
    Wilson, Sarah Kate
    Luleå tekniska universitet.
    Three non-pilot-based time and frequency estimators for OFDM1998Report (Other academic)
    Abstract [en]

    Time-domain Maximum-Likelihood (ML) estimators of time and frequency o¤sets are derived for three Orthogonal Frequency Division Multiplexing (OFDM) signal models: a pulse-shaped one-shot OFDM signal, a stream of multiple OFDM signals and an OFDM signal in a dispersive channel environment. We then develop structures to simplify their implementation. Simulation results show the relative performance and strengths of each of these three estimators.

  • 18.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    Boucheret, Marie-Laure
    Ecole National Superieure de Telecommunications, Site de Toulouse.
    Landström, Daniel
    Luleå tekniska universitet.
    Arenas, Julia Martinez
    Ecole National Superieure de Telecommunications, Site de Toulouse.
    Ödling, Per
    Luleå tekniska universitet.
    Wilson, Sarah Kate
    Luleå tekniska universitet.
    Östberg, Christer
    Ericsson Mobile Communication AB.
    Wahlqvist, Mattias
    Telia Research AB.
    Synchronization of a TDMA-OFDM frequency hopping system1998In: Pathway to a global wireless revolution: VTC '98, 48th IEEE Vehicular Technology Conference, Westin Hotel, Ottawa, Canada, 18 - 21 May 1998, Piscataway, NJ: IEEE Communications Society, 1998, Vol. 2, 1290-1294 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we present a Time Division Multiple Access-Orthogonal Frequency Division Multiplexing (TDMA-OFDM)-based radio interface proposal for the Universal Mobile Telecommunication System (UMTS). We focus on synchronization and present an implementable algorithm for the tracking of the mobiles' time and frequency offsets at the base station in the uplink. This algorithm is based on recently developed estimation methods that use redundancy introduced by the cyclic prefix. A modified Maximum Likelihood (ML) estimator for the Additive White Gaussian Noise (AWGN) channel is used to meet both implementational requirements and performance requirements for frequency-selective fading multiuser environments. Simulation results for a typical UMTS mobile channel environment show that the uncoded symbol error rate of a coherently modulated system using our synchronization scheme is virtually indistinguishable from that of a system with no time and frequency offset.

  • 19.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    Eriksson, Håkan
    Luleå tekniska universitet.
    Gustavsson, Jan-Olov
    Luleå tekniska universitet.
    Olsson, Lennart
    Luleå tekniska universitet.
    MMSE estimation of arrival time with application to ultrasonic signals1993Report (Other academic)
    Abstract [en]

    This paper deals with arrival time estimation of a narrow-band signal disturbed by white gaussian noise. In order to estimate the distance between a transmitting source and a reflecting target an estimator, based on the criterion of minimum mean square error (MMSE), is investigated. The MMSE-estimator is implemented in an experimental ultrasound pulse-echo system, and results of comparative simulations between the MAP-estimator and the MMSE-estimator are given. The results are compared to the theoretical Weiss-Weinstein lower bound. As expected, the MMSE-estimator has smaller mean square error than the MAP-estimator. For high SNRs, however, the mean square error obtained by the MAP-estimator manages to approach that of the MMSE-estimator. Other di®erences between the two estimators are revealed in additional experiments in which the range estimates are used to generate 3-dimensional surface pictures.

  • 20.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    Landström, Daniel
    Wahlqvist, Mattias
    Telia Research.
    Ödling, Per
    Östberg, Christer
    A conceptual study of OFDM-based multiple access schemes: Part 4: Tracking of time and frequency offset1996Report (Other academic)
    Abstract [en]

    This paper is part of a conceptual study of a multiuser OFDM system. In previous reports we have examined requirements for the air interface and presented uncoded performance (in terms of bit error rate) for the uplink of such systems. In this report we adopt the user allocation structure from the previous parts of the study and examine the role of channel coding. We present performance simulations that illustrate the effects of a convolutional code exploiting channel diversity, and channel estimator performance exploiting the channel correlation.

  • 21.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Edfors, Ove
    Luleå tekniska universitet.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    Wahlqvist, Mattias
    Telia Research.
    Östberg, Christer
    Telia Research.
    A conceptual study of OFDM-based multiple access schemes: Part 2: Channel estimation in the uplink1996Report (Other academic)
    Abstract [en]

    This paper deals with the design of channel estimators in the uplink of an OFDM based multi-user system. First, we propose a user allocation scheme that is based on the aim to use the correlation of the radio channel for channel estimation purposes. Further, we present the linear MMSE channel estimator based on a few pilot tones. We present an error analysis that proves valuable in the evaluation of linear channel estimators under mismatch. Finally, we present some results on the design of linear channel estimators and pilot patterns, showing by means of examplesthe importance of careful pilot positioning.

  • 22.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Edfors, Ove
    Luleå tekniska universitet.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    Wahlqvist, Mattias
    Tellia Research.
    Östberg, Christer
    Telia Research.
    A conceptual study of OFDM-based multiple access schemes: Part 3: Performance evaluation of a coded system1996Report (Other academic)
    Abstract [en]

    This paper is part of a conceptual study of a multiuser OFDM system. In previous reports we have examined requirements for the air interface and presented uncoded performance (in terms of bit error rate) for the uplink of such systems. In this report we adopt the user allocation structure from the previous parts of the study and examine the role of channel coding. We present performance simulations that illustrate the effects of a convolutional code exploiting channel diversity, and channel estimator performance exploiting the channel correlation.

  • 23.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Edfors, Ove
    Luleå tekniska universitet.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    Wahlwvist, Mattias
    Telia Research AB.
    Östberg, Christer
    Telia Research AB.
    Channel estimation in the uplink of an OFDM system1996In: Proceedings of Nordic Radio Symposium: NRS '96, Lund, Sweden, August 1996, 1996, 32-35 p.Conference paper (Refereed)
    Abstract [en]

    This paper deals with the design of linear pilot based channel estimators in the uplink of an OFDM-based multiuser system, We evaluate such estimators and pilot patterns, showing by means of examples the importance of careful pilot positioning.

  • 24.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Edfors, Ove
    Luleå tekniska universitet.
    Sandell, Magnus
    Luleå tekniska universitet.
    Wilson, Sarah Kate
    Luleå tekniska universitet.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    On channel estimation in OFDM systems1995In: Countdown to the wireless twenty-first century: 1995 IEEE 45th Vehicular Technology Conference, Chicago, Illinois, USA, July 25 - 28, 1995, Piscataway, NJ: IEEE Communications Society, 1995, Vol. 2, 815-819 p.Conference paper (Refereed)
    Abstract [en]

    The use of multi-amplitude signaling schemes in wireless OFDM systems requires the tracking of the fading radio channel. The paper addresses channel estimation based on time-domain channel statistics. Using a general model for a slowly fading channel, the authors present the MMSE and LS estimators and a method for modifications compromising between complexity and performance. The symbol error rate for a 18-QAM system is presented by means of simulation results. Depending upon estimator complexity, up to 4 dB in SNR can be gained over the LS estimator

  • 25. Beek, Jaap van de
    et al.
    Lidström, Erik
    Huawei Technologies, Stockholm.
    Cai, Tao
    Huawei Technologies, Stockholm.
    Xie, Yong
    Huawei Technologies, Chengdu.
    Rakovic, Valentin
    Ss. Cyril and Methodius University, Skopje.
    Atanasovski, Vladimir M.
    Ss. Cyril and Methodius University, Skopje.
    Gavrilovska, Liljana M.
    Ss. Cyril and Methodius University, Skopje.
    Rihijärvi, Janne
    RWTH Aachen University.
    Mähönen, Petri H.
    RWTH Aachen University.
    Dejonghe, Antoine
    IMEC, Leuven.
    Wesemael, Peter Van
    IMEC, Leuven.
    Desmet, Mattias
    IMEC, Leuven.
    REM-enabled opportunistic LTE in the TV band2012In: 2012 IEEE International Symposium on Dynamic Spectrum Access Networks (DYSPAN 2012): Bellevue, Washington, USA, 16 - 19 October 2012, Piscataway, NJ: IEEE Communications Society, 2012, 272-273 p.Conference paper (Refereed)
    Abstract [en]

    In this demonstration paper we describe a prototype of an LTE system deployment that opportunistically exploits the spectral white spaces in the upper UHF TV bands, intelligently guided in its spectum access by a radio environment map (REM). The architecture is modular in the sense that interfaces are generic and minimal. In the proposed demo we will illustrate how information of primary transmitters and other secondary transmitters as well as estimates of the radio field strength over frequency, time and space can be made available and exploited by a secondary TDD-LTE base station to make judicious decisions on its spectral occupation.

  • 26.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Popović, Branislav M.
    Huawei Technologies Sweden.
    Benefits of modulation diversity in turbo-coded OFDM systems2004In: IEEE Vehicular Technology Conference (VTC) Proceedings, ISSN 1550-2252, Vol. 59, no 2, 929-933 p.Article in journal (Refereed)
    Abstract [en]

    In this paper we show that the use of modulation diversity provides gains to punctured, turbo-coded OFDM systems. For an OFDM transmission scenario based on the downlink of the 3GPP standard for mobile communications, we show that the order-2 modulation diversity observed for the raw bit-error rate transfers to the block-error rate in a number of investigated channel environments. We demonstrate gains of up to 2.5 dB depending on the puncturing rate of the scheme and the particular channel characteristics. Alternatively, for schemes with higher puncturing rates, 2 or 3 turbo decoder iterations suffice to achieve the same performance as achieved by 8 decoder iterations in a regular transmission

  • 27.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Popović, Branislav M.
    Huawei Technologies Sweden.
    Multiple access with low-density signatures2009In: GLOBECOM 2009: 2009 IEEE Global Telecommunications Conference; Honolulu, Hawaii, USA, 30 November - 4 December 2009, Piscataway, NJ: IEEE Communications Society, 2009, 5425243Conference paper (Refereed)
    Abstract [en]

    We present sets of spreading sequences that are specifically designed to suit a belief-propagation multiuser detection structure, recently presented for overloaded system scenarios. On one hand, our sequences are of the low-density type; on the other their distance spectrum properties ensure good performance in AWGN channels. Simulations results for raw and coded bit-error probability indicate that significant performance gain is achieved over random sequences and that the loss compared to the single-user bound can be kept small.

  • 28. Beek, Jaap van de
    et al.
    Rihijärvi, Janne
    Institute for Networked Systems, RWTH Aachen University.
    Achtzehn, Andreas
    Institute for Networked Systems, RWTH Aachen University.
    Mähönen, Petri H.
    Institute for Networked Systems, RWTH Aachen University.
    TV white space in Europe2012In: IEEE Transactions on Mobile Computing, ISSN 1536-1233, E-ISSN 1558-0660, Vol. 11, no 2, 178-188 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, we study the availability of TV white spaces in Europe. Specifically, we focus on the 470-790 MHz UHF band, which will predominantly remain in use for TV broadcasting after the analog-to-digital switch-over and the assignment of the 800 MHz band to licensed services have been completed. The expected number of unused, available TV channels in any location of the 11 countries we studied is 56 percent when we adopt the statistical channel model of the ITU-R. Similarly, a person residing in these countries can expect to enjoy 49 percent unused TV channels. If, in addition, restrictions apply to the use of adjacent TV channels, these numbers reduce to 25 and 18 percent, respectively. These figures are significantly smaller than those recently reported for the United States. We also study how these results change when we use the Longley-Rice irregular terrain model instead. We show that while the overall expected availability of white spaces is essentially the same, the local variability of the available spectrum shows significant changes. This underlines the importance of using appropriate system models before making far-reaching conclusions.

  • 29.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Rihijärvi, Janne
    RWTH Aachen University.
    Achtzehn, Andreas
    Institute for Networked Systems, RWTH Aachen University.
    Mähönen, Petri H.
    RWTH Aachen University.
    UHF white space in Europe: A quantitative study into the potential of the 470-790 MHz band2011In: 2011 IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN 2011): Aachen, Germany, 3 - 6 May, 2011, Piscataway, NJ: IEEE Communications Society, 2011, 1-9 p., 5936207Conference paper (Refereed)
    Abstract [en]

    In this paper we study the availability of TV white spaces in Europe. We focus specifically on the 470-790 MHz UHF band that is still predominantly used for TV broadcasting also after the digital dividend (frequency reallocation as part of transition to digital TV), which has taken place or is ongoing in several European countries. We find that in the countries used in our studies, approximately 56% of the TV channels are unused, when averaged over the whole geographic area. Considering the average over population instead of geographic area reduced the mean available white space to 49% of the channels. Our results confirm quantitatively the often stated expectation that there are indeed fewer white spaces available in Europe compared to, for example, the United States. We also study the influence of different modeling assumptions on our results, especially focusing on the impact of the choice of propagation model. Our results show that changing from statistical ITU-R model to the Longley-Rice irregular terrain model does not cause a major change in the overall estimated availability of white spaces. However, changing the propagation model can significantly affect especially the local variability of the estimated availability of spectrum. This underlines the importance of using right system models in various studies before making too far-reaching conclusions

  • 30. Beek, Jaap van de
    et al.
    Rihijärvi, Janne
    RWTH Aachen University.
    Mähönen, Petri H.
    RWTH Aachen University.
    Intrinsic challenges (and opportunities) to deploy LTE in Europe's TV white spaces2012In: 2012 Future Network & Mobile Summit (FutureNetw 2012): Berlin, Germany, 4 - 6 July 2012, Piscataway, NJ: IEEE Communications Society, 2012, 6294241Conference paper (Refereed)
    Abstract [en]

    This contribution presents four business challenges associated with a potential secondary use of European TV white spaces by LTE networks. Based on a quantitative study for 11 representative European countries, we show that Europe's TV white spaces are relatively scarce, diminishing, spatially scattered and heterogeneous, as well as rural in nature. These intrinsic characteristics of the spectrum have implications for the exploitation scenarios by secondary LTE networks that regularly appear as promising use cases. We discuss these implications relation to three LTE use case scenarios: femtocell deployments, rural coverage deployments, and LTE broadcasting/ multicasting deployments

  • 31.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sandell, Magnus
    Luleå tekniska universitet.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    ML estimation of time and frequency offset in OFDM systems1997In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 45, no 7, 1800-1805 p.Article in journal (Refereed)
    Abstract [en]

    We present the joint likelihood (ML) symbol-time and carrier-frequency offset estimator in orthogonal frequency-division multiplexing (OFDM) systems. Redundant information contained within the cyclic prefix enables this estimation without additional pilots. Simulations show that the frequency estimator may be used in tracking mode and the time estimator in an acquisition mode.

  • 32.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sandell, Magnus
    Luleå tekniska universitet.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    ML estimation of timing and frequency offset in multicarrier systems1996Report (Other academic)
    Abstract [en]

    In this paper, we present a novel data-based method for simultaneous Maximum Likelihood (ML) symbol and carrier-frequency offset estimation in Orthogonal frequency division multiplexing (OFDM) systems. Statistical properties introduced by the cyclic (OFDM) systems. Statistical properties introduced by the cyclic prefix, a guard space between OFDM symbols, provide su±cient information about the unknown parameters. It is shown that the redundancy introduced by this cyclic prefix allows the estimation to be performed without additional pilots. Simulations show that the performance of the frequency estimator is applicable in a tracking mode while the timing estimation can be used in an acquisition mode.

  • 33.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sandell, Magnus
    Luleå tekniska universitet.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    On synchronization in OFDM systems using the cyclic prefix1996In: Proceedings of the 1996 SNRV and NUTEK Conference on Radio Sciences and Telecommunications in Luleå and Kiruna June 3-6, 1996: RVK 96 / [ed] Lars H. Zetterberg, Luleå: Luleå tekniska universitet, 1996, 663-667 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a data-based method for simultaneous Maximum Likelihood (ML) symbol timing and carrier-frequency offset estimation in Orthogonal frequency-division multiplexing (OFDM) systems. The cyclic extension, a guardspace preceding OFDM frames, is of decisive importance for this method. It is shown that the redundancy introduced by this cyclic extension allows the estimation to be performed without additional pilots. Simulations show that the performance of the frequency estimator is usable in a tracking mode while the timing estimation can be used in an acquisition mode.

  • 34.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sandell, Magnus
    Luleå tekniska universitet.
    Börjesson, Per-Ola
    Luleå tekniska universitet.
    ML estimation of time and frequecy offset in OFDM systems1998In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 45, no 7, 1800-1805 p.Article in journal (Refereed)
  • 35.
    Beek, Jaap van de
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sandell, Magnus
    Luleå tekniska universitet.
    Isaksson, Mikael
    Telia Research AB.
    Börjesson, Per Ola
    Luleå tekniska universitet.
    Low-complex frame synchronization in OFDM systems1995In: Gateway to the 21st century : record: 1995 Fourth IEEE International Conference on Universal Personal Communications, Meiji Kinenkan, Tokyo, Japan, November 6 - 10, 1995, Piscataway, NJ: IEEE Communications Society, 1995, 982-986 p.Conference paper (Refereed)
    Abstract [en]

    Orthogonal frequency-division multiplexing (OFDM) systems have gained an increased interest due to their use in wireless applications such as mobile communication systems. A novel data-based frame synchronization method for OFDM-systems is presented. OFDM frames are shown to contain sufficient information to synchronize a system without the use of pilots. The cyclic extension, preceding OFDM frames, is of decisive importance for this method. Based on only the sign bits of the in-phase and the quadrature components of the received OFDM signal, the maximum likelihood solution is derived. This solution basically consists of a correlator, a moving sum and a peak detector. The stability of the generated frame-clock is improved significantly by averaging over a few number of frames. Simulations show that this low-complex, averaging method can be used to synchronize an OFDM system on twisted pair copper wires and in slowly fading radio channels

  • 36. Beek, Jaap van de
    et al.
    Tao, Cai
    Huawei Technologies Sweden.
    Grimoud, Sébastien
    Orange Labs, Telecom R and D, Issy-les-Moulineaux.
    Sayrac, Berna
    Orange Labs, Telecom R and D, Issy-les-Moulineaux.
    Mähönen, Petri H.
    Rheinisch-Westfälische Technische Hochschule Aachen, Institute for Networked.
    Nadreddine, Jad
    Rheinisch-Westfälische Technische Hochschule Aachen, Institute for Networked.
    Rihijärvi, Janne
    Rheinisch-Westfälische Technische Hochschule Aachen, Institute for Networked.
    How a layered rem architecture brings cognition to today's mobile networks2012In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 19, no 4, 17-24 p.Article in journal (Refereed)
    Abstract [en]

    In this article, we present a layered radio environment map architecture along with its applications to the self-organizing network functionalities of heterogeneous LTE radio access networks comprising macrocells and femtocells. In this architecture, the functional blocks reappear with different spatial and temporal granularity at different architectural layers. Although the radio environment map is one of the key promising technologies to enable future cognitive radio networks, it can be already applied to provide limited cognitive capabilities to today's commercial networks too. We explain why, and show how, this architecture can support today??s LTE self-organizing network functions like automatic neighbor relation and minimization of drive tests, and also allow the smooth introduction of new radio access technologies through refarming. We also demonstrate some of the quantitative benefits adopting radio environment map technologies can bring using the minimization of drive tests as an example.

  • 37.
    Browne Mwakyanjala, Moses
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Emami, Reza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Software-defined radio transceiver for QB50 CubeSat telemetry and telecommand2016In: Proceedings of the 34th AIAA International Communications Satellite Systems Conference (ICSSC 2016), American Institute of Aeronautics and Astronautics, 2016Conference paper (Refereed)
    Abstract [en]

    This paper presents the development of a ground system based on software-defined radio for supporting both ground testing and space telemetry and telecommand of one of the nanosatellites in the QB50 mission. The QB50 project is an ongoing European Commission Seventh Framework initiative, which aims at launching a constellation of 50 CubeSats in the lower thermosphere to carry out in-situ scientific measurements. The paper discusses the implementation of amateur radio protocols and telecommunication modulation schemes on the ground system. The system setup, deployment and scheduling are also discussed using two separate ground stations. The use of different software for testing the system is detailed, the results show the operability of the developed ground system. © 2016, American Institute of Aeronautics and Astronautics Inc

  • 38.
    Browne Mwakyanjala, Moses
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Emami, Reza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    van de Beek, Jaap
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Verication of phase and frequency modulation for software-defined radio baseband systems using field data2017Conference paper (Refereed)
  • 39.
    Börjesson, Per Ola
    et al.
    Department of Applied Electronics, Lund University.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Boucheret, Marie-Laure
    Ecole Nationale Supérieure des Télécommunications.
    Landström, Daniel
    Department of Applied Electronics, Lund University.
    Arenas, Julia Martinez
    Ericsson Radio Systems AB.
    Ödling, Per
    Department of Applied Electronics, Lund University.
    Wilson, Sarah Kate
    Luleå tekniska universitet.
    Three non-pilot based time- and frequency estimators for OFDM2000In: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 80, no 7, 1321-1334 p.Article in journal (Refereed)
    Abstract [en]

    Time-domain maximum-likelihood (ML) estimators of time and frequency offsets are derived for three orthogonal frequency division multiplexing (OFDM) signal models: a pulse-shaped one-shot OFDM signal, a stream of multiple OFDM signals and an OFDM signal in a dispersive channel environment. We then develop structures to simplify their implementation. Simulation results show the relative performance and strengths of each of these three estimators.

  • 40.
    Cai, Tao
    et al.
    Huawei Technologies Sweden.
    Beek, Jaap van de
    Nasreddinne, Jad
    Institute for Networked Systems, RWTH Aachen University.
    Petrova, Marina M.
    Institute for Networked Systems, RWTH Aachen University.
    Mähönen, Petri H.
    Institute for Networked Systems, RWTH Aachen University.
    A TD-LTE prototype system with modules for general-purpose cognitive resource management and radio-environmental mapping2011In: International Journal of Wireless Information Networks, ISSN 1068-9605, E-ISSN 1572-8129, Vol. 18, no 3, 131-145 p.Article in journal (Refereed)
    Abstract [en]

    In this article we describe a demonstrator that shows how the cognitive resource manager (CRM) and the radio-environmental map (REM) can be efficiently implemented in full commercial grade cellular system (i.e., LTE system). The demonstrator shows how the modular CRM together with its open interface, the universal link-layer API (ULLA), facilitates the implementation of efficient radio resource management techniques guaranteeing the quality of service in the LTE system. The CRM, through ULLA, is able to obtain PHY/MAC status information of the link between the tested eNode B and the user equipment, and reconfigure link parameters. This measure-and-control by CRM/ULLA is independent of the underlying radio access technology, which shows the neutrality of CRM/ULLA towards PHY/MAC characteristics. The article also shows how the REM can be easily implemented in such system and how the REM provides the CRM with environmental information that enhances system management performance

  • 41.
    Cai, Tao
    et al.
    Huawei Technologies Sweden.
    Beek, Jaap van de
    Sayraç, Berna
    Orange Labs., Issy-les-Moulineaux.
    Grimoud, Sébastien
    Orange Labs., Issy-les-Moulineaux.
    Nasreddine, Jad
    Institute for Networked Systems, RWTH Aachen University.
    Rihijärvi, Janne
    Institute for Networked Systems, RWTH Aachen University.
    Mähönen, Petri H.
    Institute for Networked Systems, RWTH Aachen University.
    Design of layered radio environment maps for RAN optimization in heterogeneous LTE systems2011In: 2011 IEEE 22nd International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2011): Toronto, Ontario, Canada, 11 - 14 September 2011, Piscataway, NJ: IEEE Communications Society, 2011, 172-176 p., 6139803Conference paper (Refereed)
    Abstract [en]

    In this contribution a layered radio environment map (REM) architecture is designed and applied in the framework of radio-access network optimization for heterogeneous LTE systems that comprise both macrocells and femtocells. We define layer as the hierarchical representation of a geographical area. In each layer, different instances of the same architectural block will have different spatial/temporal granularities, associated with network functionalities. The effectiveness of the proposed architecture to support LTE functions like automatic neighbor relation (ANR) and minimization of drive tests (MDT) is discussed. In addition, we present the benefits of using such architecture in the implementation of these functions along with its potential to bring performance gains

  • 42.
    Cai, Tao
    et al.
    Huawei Technologies, Stockholm.
    Koudouridis, Georgios P.
    R&D Centre, Huawei Technologies Sweden AB.
    Johansson, Johannes D.
    R&D Centre, Huawei Technologies Sweden AB.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nasreddinne, Jad
    Institute for Networked Systems, RWTH Aachen University.
    Petrova, Marina M.
    Institute for Networked Systems, RWTH Aachen University.
    Mähönen, Petri H.
    Institute for Networked Systems, RWTH Aachen University.
    An implementation of cognitive resource management on LTE platform2010In: 2010 IEEE 21st International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2010): Istanbul, Turkey, 26 - 30 September 2010, Piscataway, NJ: IEEE Communications Society, 2010, 2663-2668 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we describe an LTE based demonstrator of the Universal Link Layer API (ULLA) and Cognitive Resource Manager (CRM) modules that are developed in ARAGORN project. The demonstrated LTE system comprises one LTE TDD eNode B and one User Equipment (UE). We first introduce ULLA and CRM framework and then demonstrate their suitability to be implemented with the existing LTE equipments. We show how, through ULLA, CRM is able to obtain PHY/MAC status information of the link between the eNode B and UE, and in turn change system parameters to achieve better resource utilization and transmission efficiency. The control logic can be implemented with simple adaptation or policy-based intelligent methods. The platform clearly shows the feasibility to use ULLA/CRM architecture for radio resource management in a LTE network. It also shows the neutrality of ULLA/CRM mechanisms towards PHY/MAC characteristics of LTE technology platform; hence the platform is viable to flexibly switch between technology platforms (e.g. between LTE access and WiFi access) under the control of ULLA/CRM

  • 43.
    Carlson, Johan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    van de Beek, Jaap
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Mohamad, Medhat
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Mbit/second Communication through a Rock Bolt Using Ultrasound2017Conference paper (Refereed)
    Abstract [en]

    This paper presents a digital communication system based on Orthogonal Frequency Division Multiplexing (OFDM) and MHz-range ultrasound, for transmission of data through solid materials and liquids. The system is tested on experiments using a off-the-shelf ultrasound transducers with a center frequency of 3.5 MHz as transmitter and receiver, respectively. The propagation medium in the experiment was a 1 m long section of an epoxy coated steel rock bolt. The results show that data rates in excess of 1 Mbit/second is attainable, using readily available hardware and software.

  • 44.
    Carlson, Johan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    van de Beek, Jaap
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Mohamad, Medhat
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Mbit/second Communication through a Rock Bolt Using Ultrasound2017Conference paper (Refereed)
    Abstract [en]

    This paper presents a digital communication system based on Orthogonal Frequency Division Multiplexing (OFDM) and MHz-range ultrasound, for transmission of data through solid materials and liquids. The system is tested on experiments using a off-the-shelf ultrasound transducers with a center frequency of 3.5 MHz as transmitter and receiver, respectively. The propagation medium in the experiment was a 1 m long section of an epoxy coated steel rock bolt. The results show that data rates in excess of 1 Mbit/second is attainable, using readily available hardware and software.

  • 45.
    Chiaraviglio, Luca
    et al.
    CNIT, Italy.
    Blefari-Melazzi, Nicola
    CNIT, Italy.
    Liu, William
    AUT, New Zealand.
    Gutierrez, Jairo A.
    AUT, New Zealand.
    van de Beek, Jaap
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Birke, Robert
    IBM Research, Switzerland.
    Chen, Lydia
    IBM Research, Switzerland.
    Idzikowski, Filip
    Faculty of Electronics and Telecommunications, Poznan University of Technology.
    Kilper, Daniel
    The University of Arizona.
    Monti, Paolo
    KTH Royal Institute of Technology.
    Wu, Jinsong
    University of Chile.
    5G in rural and low-income areas: Are we ready?2017In: Proceedings of the 8th ITU Kaleidoscope academic conference: ICTs for a Sustainable World, Piscataway, NJ: IEEE Communications Society, 2017, 99-106 p., 7805720Conference paper (Refereed)
    Abstract [en]

    Current trends in telecommunication networks foresee the adoption of the,fifth generation (5G) of wireless networks in the near fixture. However; a large number of people are living without coverage and connectivity. To face this issue, we consider the possibility of deploying 5G networks in rural and low-income zones. After detailing the current state-of-the-art, we consider the main challenges that need to be faced. Moreover; we define the main pillars to follow in order to deploy 5G networks in such zones, as well as a proposal of a future network architecture.

  • 46.
    Chiaraviglio, Luca
    et al.
    CNIT, Italy.
    Blefari-Melazzi, Nicola
    CNIT, Italy.
    Liu, William
    AUT, New Zealand.
    Gutierrez, Jairo A.
    AUT, New Zealand.
    van de Beek, Jaap
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Birke, Robert
    IBM Research, Switzerland.
    Chen, Lydia
    IBM Research, Switzerland.
    Idzikowski, Filip
    Faculty of Electronics and Telecommunications, Poznan University of Technology.
    Kilper, Daniel
    The University of Arizona.
    Monti, Paolo
    KTH Royal Institute of Technology.
    Wu, Jinsong
    University of Chile.
    5G in rural and low-income areas: Is it feasible?2017In: IEEE Communications Standards Magazine, ISSN 2471-2825Article in journal (Refereed)
    Abstract [en]

    Nowadays, at least two billion people are experiencing a complete lack of wireless cellular coverage. Such users live in rural areas and low-income regions, where the network operators are not keen to invest, mainly due to high Capital Expenditure (CapEx) and Operational Expenditure (OpEx) costs, as well as the scarcity of electricity from the grid. We tackle this challenge by proposing a 5G network explicitly designed to serve rural and low-income areas. Our solution investigates the possibility of mounting Remote Radio Heads (RRHs) on top of Unmanned Aerial Vehicles (UAVs), as well as Large Cells (LCs) to increase the coverage range. In addition, 5G-nodes are powered by solar panels and batteries. Preliminary results, obtained over three representative case studies (located in Italy, Cook Islands, and Zimbabwe) show that providing connectivity in rural and low-income areas by means of the proposed 5G architecture is feasible. At the same time, we also show that the monthly subscription fee paid by the users can be kept sufficiently low, e.g., less than 1 [EUR/month] in low-income areas, and less than 10 [EUR/month] in rural regions.

  • 47.
    Chiaraviglio, Luca
    et al.
    Consorzio Nazionale Interuniversitario per le Telecomunicazioni and University of Rome Tor Vergata.
    Blefari-Melazzi, Nicola
    Consorzio Nazionale Interuniversitario per le Telecomunicazioni and University of Rome Tor Vergata.
    Liu, William
    Auckland University of Technology.
    Gutiérrez, Jairo A.
    Auckland University of Technology.
    van de Beek, Jaap
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Birke, Robert
    IBM Research, Switzerland.
    Chen, Lydia
    IBM Research.
    Idzikowski, Filip
    Poznan University of Technology.
    Kilper, Daniel
    University of Arizona.
    Monti, Paolo
    KTH Royal Institute of Technology.
    Bagula, Antoine
    University of Western Cape.
    Wu, Jinsong
    University of Chile.
    Bringing 5G into Rural and Low-Income Areas: Is It Feasible?2017In: IEEE Communications Standards Magazine, ISSN 2471-2825, Vol. 1, no 3, 50-57 p.Article in journal (Refereed)
    Abstract [en]

    Nowadays, at least two billion people are experiencing a complete lack of wireless cellular network coverage. These users live in rural areas and low-income regions, where network operators are not keen to invest, mainly due to high capital expenditure and operational expenditure costs, as well as the scarcity of electricity from the grid. We tackle this challenge by proposing a 5G network explicitly designed to serve rural and low-income areas. Our solution investigates the possibility of mounting remote radio heads on top of unmanned aerial vehicles, as well as large cells (LCs) to increase the coverage range. In addition, 5G nodes are powered by solar panels and batteries. Preliminary results, obtained over three representative case studies located in Italy, Cook Islands, and Zimbabwe, show that providing connectivity in rural and low-income areas by means of the proposed 5G architecture is feasible. At the same time, we also show that the monthly subscription fee paid by the users can be kept sufficiently low, that is, less than €1/month in low-income areas, and around €11/month in rural regions.

  • 48.
    Edfors, Ove
    et al.
    Department of Applied Electronics, Lund University.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sandell, Magnus
    Bell Labs, Lucent Technologies, Windmill Hill Business Park, Swindon.
    Wilson, Sarah Kate
    Luleå tekniska universitet.
    Börjesson, P-O
    Department of Applied Electronics, Lund University.
    Analysis of DFT-Based Channel Estimators for OFDM2000In: Wireless personal communications, ISSN 0929-6212, E-ISSN 1572-834X, Vol. 12, no 1, 55-70 p.Article in journal (Refereed)
    Abstract [en]

    In this paper we analyze the performance of three low-complexity channel estimators, based on the discrete Fourier transform (DFT), for orthogonal frequency-division multiplexing (OFDM) systems. Estimators of this type have been analyzed for discrete-time channels, and we extend this analysis to continuous-time channels. We present analytical expressions for their mean-squared error (MSE) and evaluate their complexity vs. symbol-error rate (SER) for 16-QAM. The analysis shows that this type of estimators may experience an irreducible error floor at high SNRs. However, in one of the three estimators the error floor can be eliminated while the complexity stays low and the performance is maximized.

  • 49.
    Edfors, Ove
    et al.
    Luleå tekniska universitet.
    Sandell, Magnus
    Luleå tekniska universitet.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Landström, Daniel
    Luleå tekniska universitet.
    Sjöberg, Frank
    Luleå tekniska universitet.
    An introduction to orthogonal frequency-division multiplexing1997Report (Other academic)
    Abstract [en]

    This report is an introduction to orthogonal frequency-division multiplexing (OFDM). The focus is on signal processing areas pursued by our research group at Luleå University of Technology. We present an historical background and some frequently used system models. Typical areas of applications are also described, both wireless and wired. In addition to the general overview, the addressed areas include synchronization, channel estimation and channel coding. Both time and frequency synchronization are described, and the effects of synchronization errors are presented. Different types of channel estimators are described, where the focus is on low-complexity algorithms, and in this context, advantages and disadvantages of coherent and differential modulation are also discussed. Channel coding is described, both for wireless and wired systems, and pointers are included to evaluation tools and bitloading algorithms. An extensive bibliography is also included.

  • 50.
    Edfors, Ove
    et al.
    Luleå tekniska universitet.
    Sandell, Magnus
    Luleå tekniska universitet.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Landström, Daniel
    Luleå tekniska universitet.
    Sjöberg, Frank
    Luleå tekniska universitet.
    An introduction to orthogonal frequency-division multiplexing1997Report (Other academic)
    Abstract [en]

    This report is an introduction to orthogonal frequency-division multiplexing (OFDM). The focus is on signal processing areas pursued by our research group at Luleå University of Technology. We present an historical background and some frequently used system models. Typical areas of applications are also described, both wireless and wired. In addition to the general overview, the addressed areas include synchronization, channel estimation and channel coding. Both time and frequency synchronization are described, and the effects of synchronization errors are presented. Different types of channel estimators are described, where the focus is on low-complexity algorithms, and in this context, advantages and disadvantages of coherent and differential modulation are also discussed. Channel coding is described, both for wireless and wired systems, and pointers are included to evaluation tools and bitloading algorithms. An extensive bibliography is also included.

12 1 - 50 of 77
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf