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  • 1.
    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.

  • 2.
    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)
  • 3.
    Tayebeh, Taheri
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nilsson, Rickard
    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.
    Hybrid spectral precoding/windowing for low-latency OFDM2017Conference paper (Refereed)
  • 4.
    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.

  • 5.
    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 Ultrasound2017In: 2017 IEEE International Ultrasonics Symposium, IEEE, 2017Conference paper (Refereed)
  • 6.
    Mohamad, Medhat
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nilsson, Rickard
    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.
    An SDR-based prototype of spectrally-precoded OFDM2017Conference paper (Refereed)
    Abstract [en]

    Spectrally precoded OFDM is a recent approach that aims for the suppression of the OOB, as well as the in-band gap, emissions in OFDM systems. Theoretically, the technique shows High suppression of the OOB and the in-band gap emissions. Although, practically hardware impairments may limit the precoder's performance. Yet, this demonstration shows that despite the hardware impairments, implemented spectrally precoded OFDM generates emissions tens of decibels less than that of plain OFDM. Therefore, the demonstration proves that communications links are less vulnerable to interference coming from spectrally precoded OFDM signals than to interference coming from plain OFDM signals

  • 7.
    Pitaval, Renaud-Alexandre
    et al.
    Huawei Technologies Sweden AB.
    Popovic, Branislav M.
    Huawei Technologies Sweden AB.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    N-continuous SC-FDMA and its Polarized Transmission and Reception2017In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857Article in journal (Refereed)
    Abstract [en]

    This paper investigates the application of Ncontinuous spectral projection precoding design to Single-Carrier Frequency-Division Multiple Access (SC-FDMA). It first considers a general orthogonal projection-based precoded system with an improved iterative receiver and analyzes its ultimate performance in an additive white Gaussian noise channel, both in terms of achievable throughput and symbol-error rates. For N-continuous SC-FDMA, the distribution of the symbol errors is very much a-symmetric; few base pulses carry the lion share of the self-induced interference, resulting in a zero throughput. We show that an optimized transmission and reception scheme based on a polarized use of the base pulses can satisfactorily deal with this asymmetry, and the end-to-end throughput can be recovered to be close to optimal. Applying a similar scheme to N-continuous OFDM enables also an improved performance in the high-SNR regime where the interference effect strikes the most.

  • 8.
    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)
  • 9.
    Landström, Anders
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Simonsson, Arne
    Ericsson Research AB.
    Thurfjell, Magnus
    Ericsson Research AB.
    Ökvist, Peter
    Ericsson Research AB.
    Measurement-Based Stochastical mmWave Channel Modeling2016In: 2016 IEEE Globecom Workshops (GC Wkshps), Piscataway, NJ: IEEE Communications Society, 2016, 7848959Conference paper (Refereed)
    Abstract [en]

    Emerging mmWave technology will require newchannel models. Compared to the lower frequency bands,mmWaves will be more reflected and absorbed but less diffracted.Hence, placement of individual physical structures in the en-vironment will affect the propagation much more than before,providing a challenge for channel modeling. At the same time,however, an increasing amount of information about the topologyof the physical environment, in particular for buildings, is madeavailable through better measurement equipment and servicesfor obtaining 3D data. We propose a Monte-Carlo approachfor channel modeling where interactions between mmWaves andthe surrounding small-scale environment can be included, givena stochastic representation. This method is not only suitablefor assessment of basic effects such as material reflection andabsorption, but can also in the future be extended to variousadditional effects such as weather, traffic, foliage, etc. Theframework is verified against 15 GHz measurements from anurban environment, demonstrating how major reflection pathscan be replicated by modeling the closest buildings.IndexTerms

  • 10.
    Taheri, Tayebeh
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nilsson, Rickard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Asymmetric Transmit-windowing for low-latency and robust OFDM2016In: Globecom Workshops (GC Wkshps), 2016 IEEE, Piscataway, NJ: IEEE Communications Society, 2016, 7848842Conference paper (Refereed)
    Abstract [en]

    In the content of low-latency 5G systems we revisit in this paper the question of shortening the cyclic prefix in windowed OFDM system without sacrificing OOB power emissions or increasing the ISI and ICI. Based on interference power analysis we propose a new asymmetric window which provides 30 percent cyclic prefix length reduction without increasing adjacent-channel interference power or channel-induced ISI/ICI.

  • 11.
    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

  • 12.
    Nilsson, Rickard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Channel Measurements in an Open-pit Mine using USRPs:: 5G – Expect the Unexpected2016In: 2016 IEEE Wireless Communications and Networking Conference: WCNC 2016, Doha, Qatar, 3-7  April 2016, 2016, 212-217 p., 7564672Conference paper (Refereed)
    Abstract [en]

    In this paper, we describe and analyze the results of a radio channel measurement campaign in an extreme industrial environment; a large open-pit copper mine targeted by next generation’s highly voiced device communications. We present a practical and efficient method to perform robust and high-sensitivity impulse response measurements without a common clock reference using the widely spread USRP hardware. With this technique, we performed channel sounding on a large number of locations within the mine. One important observation is that the radio channel’s impulse response in an open-pit mine can often be more than 10 microseconds long, and much unlike the responses normally associated with Wi-Fi and mobile cellular radio systems, which poses serious design challenges for future 5G radio systems.

  • 13.
    Landström, Anders
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Transmitter Localization for 5G mmWave REMs by Stochastic Generalized Triangulation2016In: 23rd International Conference on Telecommunications (ICT 2016), Piscataway, NJ: IEEE Communications Society, 2016, 789-793 p., 7500413Conference paper (Refereed)
    Abstract [en]

    Future mobile networks will need new tools to deal with the challenges of emerging technologies. In particular, more flexible networks will require localization of transmitters in the networks. In this work we present a novel method for transmitter localization, suitable for rich multipath mmWave 5G scenarios such as dense urban environments. Our work combines stochastic estimation of Radio Environmental Maps (REMs) with the well known concept of triangulation, generalizing the latter into a method for localization in anisotropic propagation environments. It can be considered a conceptual bridge from classical distance-based triangulation into a generalized version where the propagation environment is taken into account. The result is a highly flexible tool for network planning in general and transmitter localization in particular.

  • 14.
    Mohamad, Medhat
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nilsson, Rickard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Minimum-EVM N-continuous OFDM2016In: 2016 IEEE International Conference on Communications (ICC): Kuala Lumpur, 22-27 May 2016, Piscataway, NJ: IEEE Communications Society, 2016, 7511164Conference paper (Refereed)
    Abstract [en]

    The N-continuous precoder for the suppression ofOOB emission in OFDM systems that minimizes the EVM isintroduced. We show that the minimum in-band interference dueto the introduced precoding approach is 3 dB less than the inbandinterference of existing N-continuous precoders. Moreover,we introduce a novel practical block precoder that approachesthe performance of the suggested optimal precoder. We analyzethe spectrum of the OFDM signal after block precoding, the inbandinterference due to block precoding and the effect of blockprecoding on the BER. The price to pay for block precoding isthe computational complexity that grows linearly with the blocksize.

  • 15.
    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)
  • 16.
    Eriksson, Mats
    et al.
    Arctos Labs Scandinavia AB.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Rural 5G: Oxymoron or Opportunity?2015In: IEEE ComSoc Technology News, no NovemberArticle in journal (Other (popular science, discussion, etc.))
  • 17.
    Perotti, Alberto G.
    et al.
    Huawei Technologies Sweden.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems. Huawei Technologies Sweden.
    Popovic, Branislav M.
    Huawei Technologies Sweden.
    Downlink Overloaded Multiple Access Based on Constellation Expansion2015In: 2014 IEEE Globecom Workshops: GC Wkshps 2014, Austin, 8-12 December 2014, Piscataway, Nj: IEEE Communications Society, 2015, 977-982 p.Conference paper (Refereed)
    Abstract [en]

    A new overloaded multiple access scheme for the downlink of wireless systems is presented. It performs simultaneous transmission of multiple data streams intended for users experiencing similar signal-to-noise ratios (SNR). The proposed scheme performs stream multiplexing by mapping the coded bits of each stream onto the labels of an expanded constellation according to a time-varying pattern designed for providing the same level of protection against errors to all streams. Using this scheme, multiple data streams can be concurrently transmitted on the same time-frequency resource blocks of OFDMA systems, thus achieving a higher aggregate spectral efficiency and tighter delay constraints.

  • 18.
    Mohamad, Medhat
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nilsson, Rickard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    An analysis of out-of-band emission and in-band interference for precoded and classical OFDM systems2015In: European Wireless 2015: 21th European Wireless Conference, 20-22 May 2015, Budapest, Hungary, Piscataway, NJ: IEEE Communications Society, 2015, 7147703Conference paper (Refereed)
    Abstract [en]

    In this paper we present analytical expressions for the out-of-band (OOB) emission and in-band interference of two different OOB suppressed OFDM-systems; classical low-pass filtered and precoded. Then, we analytically compare their performance in terms of OOB emission suppression and introduced level of in-band interference. We analyse the fact that the in-band interference introduced by the filter depends on the length of the cyclic prefix as well as the behavior of the channel while that of the precoded OFDM does not. The analysis confirms that edged subcarriers suffer higher in-band interference than central subcarriers. Moreover, frequency precoders, for a specific choice of notching frequencies, can outperform time precoders.

  • 19.
    Gavrilovska, Liljana M.
    et al.
    Ss. Cyril and Methodius University, Skopje.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Xie, Yong
    Huawei Technologies, Chengdu.
    Lidström, Erik
    Huawei Technologies, Stockholm.
    Riihijärvi, Janne
    RWTH Aachen University.
    Mähönen, Petri H.
    RWTH Aachen University.
    Atanasovski, Vladimir M.
    Ss. Cyril and Methodius University, Skopje, Faculty of Electrical Engineering, Ss. Cyril and Mehtodius, Skopje.
    Denkovski, Daniel
    Faculty of Electrical Engineering, Ss. Cyril and Mehtodius, Skopje.
    Rakovic, Valentin
    Faculty of Electrical Engineering, Ss. Cyril and Mehtodius, Skopje.
    Enabling LTE in TVWS with radio environment maps: from an architecture design towards a system level prototype2014In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 53, 62-72 p.Article in journal (Refereed)
    Abstract [en]

    This paper reports recent prototyping efforts that show the feasibility of the radio environmental map to enable efficient exploitation of TV white spaces by a cellular LTE system. We describe a flexible REM backend implementation, fully integrated with standard-compliant operational LTE base station equipment. Simulations results indicate that REMs enhance white-space detection by their means to incorporate accurate and local channel propagation information, while experimental laboratory results illustrate the feasibility and performance of transmitter localization capabilities in a REM.

  • 20.
    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.

  • 21. 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.

  • 22. 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.

  • 23. 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

  • 24. 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.

  • 25.
    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

  • 26.
    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

  • 27.
    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

  • 28.
    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

  • 29. 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

  • 30.
    Sun, Guolin
    et al.
    Huawei Technologies Sweden.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    A method of signaling precoder information for dynamical spectrum shaping2010In: 2010 6th International Conference on Wireless Communications, Networking and Mobile Computing (WiCOM 2010): Chengdu City, China, 23 - 25 September 2010, Piscataway, NJ: IEEE Communications Society, 2010, 5600884Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose a method for signalling precoder information in cognitive radio networks employing precoded OFDM. In this way, radio transmitters in said cognitive radio networks change their spectral occupancy from one time to another, characterized by the steps of 1. The network determines a suitable precoder uniquely characterized by a codebook index from a finite codebook of precoders, said codebook being known at both the network-side and by the mobile units. 2. The network informs the relevant mobile units about the precoder to use by broadcasting the codebook index Meanwhile, we propose several measurement based optimization methods for spectrum shaping to determine the suitable precoder from, for instance, a database of interference information, or feedback information from UEs about their current interference and noise environment, then notify the precoder information over a CPC. We could use a codebook of precoders each being designed for a certain radio scenario, this precoder jointly considering noise level and frequency band. We could use a codebook with precoders forcing the OFDM signal to be N-continuous and where said codebook index is directly related to the continuity order N. We also could use a codebook with precoders forcing the spectrum of the OFDM signal to be zero at pre-defined frequencies f 0...f M, and where said codebook index is directly related to the said frequencies. f 0...f M.

  • 31.
    Sun, Guolin
    et al.
    Huawei Technologies Sweden.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Simple distributed interference source localization for radio environment mapping2010In: 2010 IFIP Wireless Days (WD 2010): Venice, Italy, 20 - 22 October 2010, IEEE Communications Society, 2010, 5657755Conference paper (Refereed)
    Abstract [en]

    In order to construct a radio environmental map that can help navigating secondary communication in TV bands, we present a new method of interference source localization for cognitive radio networks. Our low-cost, high-precision localization method, operates without any prior knowledge of the interference source other than transmitter power. It can be divided into two steps: an estimation step at each sensor based on classical methods to estimate the angle of arrival and the received signal power, followed by an SNR-aided fusion. Simulation results show that tens of sensor nodes each having two antennas in a large-scale area setting are enough to achieve accurate location. The proposed location method is practical, economic and essential for blind interference source localization in cognitive radio networks

  • 32.
    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

  • 33. 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

  • 34. 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

  • 35.
    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

  • 36.
    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.

  • 37. 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

  • 38.
    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.

  • 39.
    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

  • 40.
    Popović, Branislav M.
    et al.
    Huawei Technologies Sweden.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    User traffic multiplexing on OFDM downlink2004In: Proceedings of the 2004 IEEE International Symposium on Spread Spectrum Techniques and Applications: 30 August - 2 September 2004, Sydney, Australia, Piscataway, NJ: IEEE Communications Society, 2004, 429-433 p.Conference paper (Refereed)
    Abstract [en]

    A user traffic multiplexing scheme for the downlink of an OFDM cellular system is proposed and evaluated. The scheme is based on the set of orthogonal time-frequency (T-F) patterns obtained from a generic Costas sequence. An inter-cell interference averaging method, based on randomly variable cyclic time offsetting of the whole set of orthogonal T-F patterns, is also part of the scheme. The time offset is changed for each transmission time interval, according to a cell-specific multi-level pseudo-random sequence. In such a way the inter-cell OFDM interference becomes limited and noise-like, while no resource planning on the system level is required

  • 41.
    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.

  • 42.
    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.

  • 43.
    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).

  • 44.
    Landström, Daniel
    et al.
    Department of Electrosciences, Lund Institute of Technology, Luleå tekniska universitet, Department of Applied Electronics, Lund University.
    Ödling, Per
    Department of Applied Electronics, Lund University.
    Börjesson, Per Ola
    Lunds universitet, Luleå tekniska universitet, Lund Institute of Technology, Department of Applied Electronics.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Uplink OFDM synchronization of future multiuser radio systems1999In: Proceedings of radiovetenskap och kommunikation: Karlskrona 14-17 juni 1999 / RVK 99 / [ed] Jan-Olof Gustafsson, Karlskrona: Högskolan i Karlskrona/Ronneby , 1999Conference paper (Refereed)
  • 45.
    Landström, Daniel
    et al.
    Department of Electrosciences, Lund Institute of Technology.
    Beek, Jaap van de
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Wilson, Sarah Kate
    Luleå tekniska universitet.
    Ödling, Per
    Department of Electrosciences, Lund Institute of Technology.
    Börjesson, Per Ola
    Symbol time offset estimation in coherent OFDM systems1999In: IEEE International Conference on Communications: ICC '99, Piscataway, NJ: IEEE Communications Society, 1999, Vol. 1, 500-505 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents a symbol time offset estimator for coherent OFDM systems. This estimator exploits both the redundancy in the cyclic prefix and the pilot symbols used for channel estimation. The estimator is robust against frequency offsets and is suitable for use in dispersive channels. We base the estimator on the ML estimator for the AWGN channel. Simulations of an example system indicate a system performance as close as 0.3 dB to a perfectly synchronized system. Compared to an estimator not using pilots, our estimator's performance could allow a shorter cyclic prefix and thus a more spectrally efficient system

  • 46.
    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.

  • 47.
    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)
  • 48.
    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.

  • 49.
    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)
  • 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.
    Wilson, Sarah Kate
    Luleå tekniska universitet.
    Börjesson, Per-Ola
    Luleå tekniska universitet.
    OFDM channel estimation by singular value decomposition1998In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 46, no 7, 931-939 p.Article in journal (Refereed)
12 1 - 50 of 75
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