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  • 1. Baldemair, Robert
    et al.
    Dahlman, Erik
    Fodor, Gabor
    Mildh, Gunnar
    Parkvall, Stefan
    KTH.
    Selén, Yngve
    Tullberg, Hugo
    Balachandran, Kumar
    Evolving Wireless Communications2013In: IEEE Vehicular Technology Magazine, ISSN 1556-6072, E-ISSN 1556-6080, Vol. 8, no 1, p. 24-30Article in journal (Refereed)
    Abstract [en]

    The wireless-access networks of today will have to evolve in several ways in order to address the challenges and expectations of the future. New technology components will be introduced as part of the evolution of current wireless-access technologies, such as high-speed packet access (HSPA) and long-term evolution (LTE). However, additional components may also constitute future new wireless-access technologies, which may complement the evolved technologies. Examples of such new technology components are new ways of accessing spectrum and substantially higher frequency ranges, the introduction of massive antenna configurations, direct device-to-device communication, and ultradense deployments.

  • 2. Boccardi, Federico
    et al.
    Andrews, Jeffrey
    Elshaer, Hisham
    Dohler, Mischa
    Parkvall, Stefan
    KTH, School of Electrical Engineering (EES), Communication Theory. Univ Calif San Diego, San Diego.
    Popovski, Petar
    Singh, Sarabjot
    Why to Decouple the Uplink and Downlink in Cellular Networks and How To Do It2016In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 54, no 3, p. 110-117Article in journal (Refereed)
    Abstract [en]

    Ever since the inception of mobile telephony, the downlink and uplink of cellular networks have been coupled, that is, mobile terminals have been constrained to associate with the same base station in both the downlink and uplink directions. New trends in network densification and mobile data usage increase the drawbacks of this constraint, and suggest that it should be revisited. In this article we identify and explain five key arguments in favor of downlink/uplink decoupling based on a blend of theoretical, experimental, and architectural insights. We then overview the changes needed in current LTE-A mobile systems to enable this decoupling, and then look ahead to fifth generation cellular standards. We demonstrate that decoupling can lead to significant gains in network throughput, outage, and power consumption at a much lower cost compared to other solutions that provide comparable or lower gains.

  • 3.
    Furuskär, Anders
    et al.
    Ericsson AB, SE-164 80 Stockholm, Sweden.
    Parkvall, Stefan
    Ericsson Research, Sweden.
    Persson, Magnus
    Ericsson Research, Sweden.
    Samuelsson, Maria
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Performance of WCDMA High Speed Packet Data2002In: IEEE 55TH VEHICULAR TECHNOLOGY CONFERENCE, VTC SPRING 2002, VOLS 1-4, PROCEEDINGS, New York: IEEE , 2002, p. 1116-1120Conference paper (Refereed)
    Abstract [en]

    WCDMA release 5 supports peak bitrates for data services in the order of 10 Mbit/s, together with reduced delays and increased system throughput. In this paper, a brief introduction to release 5 is given and radio resource management principles associated with the high speed packet data bearers are discussed. Scheduling performance for WWW services, provision of bearers for streaming services, as well as the simultaneous use of high speed packet data bearers and conversational bearers is elaborated upon. Simulation results indicate that with appropriate radio resource management, all the above challenges may be successfully dealt with.

  • 4.
    Ottersten, Björn
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Astély, David
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Kristensson, Martin
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    A Statistical Approach to Subspace Based Estimation with Applications in Telecommunications1996Conference paper (Other academic)
  • 5.
    Ottersten, Björn
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Astély, David
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Kristensson, Martin
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Parkvall, Stefan
    KTH, School of Electrical Engineering (EES), Signal Processing.
    A Statistical Approach to Subspace Based Estimation with Applications in Telecommunications1997In: 2nd International Workshop on TLS and Errors-in-Variables Modeling / [ed] Huffel, S. Van, SIAM , 1997, p. 285-294Chapter in book (Other academic)
  • 6.
    Parkvall, Stefan
    et al.
    Ericsson Research.
    Furuskär, Anders
    Ericsson Research.
    Dahlman, Erik
    Ericsson Research.
    Evolution of LTE toward IMT-Advanced2011In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 49, no 2, p. 84-91Article in journal (Refereed)
    Abstract [en]

    This article provides a high-level overview of LTE Release 10, sometimes referred to as LTE-Advanced. First, a brief overview of the first release of LTE and some of its technology components is given, followed by a discussion on the IMT-Advanced requirements. The technology enhancements introduced to LTE in Release 10, carrier aggregation, improved multi-antenna support, relaying, and improved support for heterogeneous deployments, are described. The article is concluded with simulation results, showing that LTE Release 10 fulfills and even surpasses the requirements for IMT-Advanced.

  • 7.
    Parkvall, Stefan
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Klang, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Wahlberg, Bo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Carlemalm, Catharina
    Signals and Systems, Uppsala University, P.O Box 534. SE-751 21 Uppsala, Sweden.
    Advanced Detectors for Multi-User Wireless Communications1999In: RadioVetenskap och Kommunikation (RVK), 1999, p. 407-410Conference paper (Other academic)
  • 8.
    Parkvall, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ström, Erik G.
    Sensitivity Analysis of Linear DS-CDMA Detectors to Propagation Delay Estimation Errors1995In: Proceedings IEEE Global Telecommunications Conference, 1995, p. 1872-1876Conference paper (Refereed)
    Abstract [en]

    An asynchronous direct-sequence code division multiple access (DS-CDMA) communication system operating over an additive white Gaussian noise (AWGN) channel is considered. In many applications, the near-far problem can be the limiting factor. Several near-far resistant receivers have therefore been proposed (e.g., the decorrelating receiver). These receivers assume perfect knowledge of the propagation delay from all users to the receiver. In practice, the delays are estimated and therefore subject to estimation errors. The performance penalty these errors impose on linear detectors, especially the decorrelating detector, is evaluated

  • 9.
    Parkvall, Stefan
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Strom, Erik G
    Department of Signals and Systems, Chalmers University of Technology, 412 96 G¨oteborg, Sweden.
    Milstein, Laurence B
    Wireless Communication, University of California, San Diego, La Jolla, CA 92093 USA.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Asynchronous near-far resistant DS-CDMA receivers without a priori synchronization1999In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 47, no 1, p. 78-88Article in journal (Refereed)
    Abstract [en]

    In this paper, several receivers for data demodulation in an asynchronous direct-sequence code-division multiple access (DS-CDMA) system operating without prior knowledge of the propagation delays are proposed and compared. Special attention is paid to the near-far problem, and the proposed schemes are numerically shown to he near-far resistant, The near-far resistance is obtained by estimating the a priori unknown propagation delay using a subspace-based technique. Quantities obtained in the estimation procedure are used to design a filter used for suppression of interference, according to the minimum mean square error criterion. Either a decision feedback technique or a simple two-state Viterbi algorithm is subsequently used for the data demodulation in the uncoded case, By extending the trellis used in the Viterbi algorithm, error correcting coding is easily implemented.

  • 10.
    Parkvall, Stefan
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ström, Erik G
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    The impact of timing errors on the performance of linear DS-CDMA receivers1996In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 14, no 8, p. 1660-1668Article in journal (Refereed)
    Abstract [en]

    In this paper, an asynchronous direct-sequence code-division multiple-access (DS-CDMA) communication system operating over an additive white Gaussian noise (AWGN) channel is considered. In many applications, the near-far problem can be the limiting factor for the capacity of a DS-CDMA system. Several near-far resistan t receivers have, therefore, been proposed (e.g., the decorrelating receiver). These receivers assume perfect knowledge of the propagation delay from all users to the receiver. In practice, the delays are estimated and therefore subject to errors. The performance degradation these errors impose on linear detectors, especially the decorrelating detector, is the topic of this paper.

  • 11.
    Skoglund, Mikael
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Giese, Jochen
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Code design for combined channel estimation and error protection2002In: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 48, no 5, p. 1162-1171Article in journal (Refereed)
    Abstract [en]

    We consider the problem of data transmission over a linear-filter channel with an unknown filter response. Traditionally, the various operations (equalization, detection, decoding) carried out by the receiver of a system that operates over an unknown channel assume access to high-quality estimates of the channel parameters. Such estimates are typically computed by a separate device for channel identification. In contrast, this paper focuses on combined channel estimation, equalization, and decoding. We also study the problem of code design, assuming such combined decoding. More precisely, we investigate nonlinear block coding and present a design criterion and a design algorithm, under the assumptions that a statistical description of the channel is available, and that the structure of the decoder is known to the transmitter. Numerical simulations demonstrate that the new scheme is capable of outperforming four different benchmark schemes.

  • 12.
    Skoglund, Mikael
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Code design for combined channel estimation and error correction coding2000In: IEEE International Symposium on Information Theory - Proceedings, IEEE Information Theory Society , 2000, p. 74-Conference paper (Refereed)
    Abstract [en]

    The problem of data transmission over an unknown channel is considered and an approach to code design for joint channel estimation, equalization and error correction is proposed. In contrast to most traditional approaches, where the receiver is designed given knowledge of the code used at the transmitter, this paper proposes an approach where the code is designed based on knowledge of the receiver structure and the statistical properties of the channel.

  • 13.
    Ström, Erik G
    et al.
    University of Florida, Dept . of Electrical Engineering, 405 CSE Bldg., Gainesville, Florida 32611, USA.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Miller, Scott L.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Complexity Reduction of Direct Sequence Code Division Multiple Access Receivers1994In: IEEE International Conference on Communications, 1994. SUPERCOMM/ICC ’94, Conference Record, ’Serving Humanity Through Communications.’, IEEE , 1994, p. 1643-1647Conference paper (Refereed)
    Abstract [en]

    Considers an asynchronous direct-sequence code division multiple access (DS-CDMA) communication system over an AWGN channel. The authors are interested in reducing the computational complexity of a receiver by lowering the dimensionality of the received vector. Dimension reduction has previously been done in an ad hoc manner by several researchers. The present authors derive an optimum form of dimension reduction. The optimality criteria is that the Cramer-Rao bound on estimators of propagation delay, received phase and power are invariant to the reduction transform.

  • 14.
    Ström, Erik G
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Miller, Scott L
    Department of Electrical Engineering, University of Florida, Gainesville, FL 3261 1 USA.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    DS-CDMA synchronization in time-varying fading channels1996In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 14, no 8, p. 1636-1642Article in journal (Refereed)
    Abstract [en]

    Herein, the problem of estimating propagation delays of the transmitted signals in a direct-sequence code-division multiple access (DS-CDMA) system operating over fading channels is considered. Even though this study is limited to the case when the propagation delays are fixed during the observation interval, the channel gain and phase are allowed to vary in time. Special attention is given to the near-far problem which is catastrophic for the standard acquisition algorithm. An estimator based on subspace identification techniques is proposed, and the Cramer-Rao bound, which serves as an optimality criterion, is derived. The Cramer-Rao bound is shown to be independent of the near-far problem, which implies that there is no fundamental reason for propagation delay estimators to be near-far limited. Furthermore, the proposed algorithm is experimentally shown to be robust against the near-far problem.

  • 15.
    Ström, Erik G
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Miller, Scott L
    Department of Electrical Engineering, University of Florida, Gainesville, FL 3261 1 USA.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Propagation delay estimation in asynchronous direct-sequence code-division multiple access systems1996In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 44, no 1, p. 84-93Article in journal (Refereed)
    Abstract [en]

    In an asynchronous direct-sequence code-division multiple access CDS-CDMA) communication system, the parameter estimation problem, i.e., estimating the propagation delay, attenuation and phase shift of each user's transmitted signal, may be complicated by the so-called near-far problem. The near-far problem occurs when the amplitudes of the users' received signals are very dissimilar, as the case might be in many important applications, In particular, the standard method for estimating the propagation delays will fail in a near-far situation, Several new estimators, the maximum likelihood, an approximative maximum likelihood and a subspace-based estimator, are therefore proposed and are shown to be robust against the near-far problem, No knowledge of the transmitted bits is assumed, and the proposed estimators can thus be used for both acquisition and tracking. In addition, the Cramer-Rao bound is derived for the parameter estimation problem.

  • 16.
    Ström, Erik G
    et al.
    University of Florida, Dept . of Electrical Engineering, 405 CSE Bldg., Gainesville, Florida 32611, USA.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Miller, Scott L.
    Department of Electrical Engineering, University of Florida, Gainesville, FL 3261 1 USA.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Sensivity Analysis of Near-Far Resistant DS-CDMA Receivers to Propagation Delay Estimation Errors1994In: Proceedings of IEEE 44th Vehicular Technology Conference, IEEE , 1994, p. 757-761Conference paper (Refereed)
    Abstract [en]

    We consider an asynchronous direct-sequence code division multiple access (DS-CDMA) communication system operating over an AWGN channel. In certain applications, the near-far problem can be the limiting factor for the capacity of a DS-CDMA system. Several near-far resistant receivers have therefore been proposed (e.g., the decorrelating receiver). These receivers assume perfect knowledge of the propagation delay from all users to thereceiver. In practice, the delays need to be estimated and will thus be subject to estimation errors. We evaluate the performance penalty these errors will impose on previously proposed near-far resistant receivers.

  • 17.
    Ström, Erik G
    et al.
    University of Florida, Dept . of Electrical Engineering, 405 CSE Bldg., Gainesville, Florida 32611, USA.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Miller, Scott L.
    University of Florida, Dept . of Electrical Engineering, 405 CSE Bldg., Gainesville, Florida 32611, USA.
    Ottersten, Björn E.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Propagation Delay Estimation of DS-CDMA Signals in a Fading Environment1994In: IEEE Global Telecommunications Conference, Communication Theory Mini-Conference (1994 IEEE GLOBECOM), 1994, p. 85-89Conference paper (Refereed)
    Abstract [en]

    The problem considered is of estimating propagation delays of the transmitted signals in a direct sequence code division multiple access (DS-CDMA) system operating over fading channels. Special attention is given to the near-far problem. An estimator based on subspace identification techniques is proposed. The Cramer-Rao bound is presented and used as a benchmark when evaluating the performance of the estimator.

  • 18.
    Ström, Erik G
    et al.
    Dept. EE, University of Florida, 405 CSE Building, Gainesville, Florida 32611, USA.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Near-Far Resistant Propagation Delay Estimators for Asynchronous Direct-Sequence Code Division Multiple Access Systems1994In: Lecture Notes in Computer Science: Mobile Communications, Proceedings 1994 International Zurich Seminar on Digital Communications, Springer-Verlag , 1994, p. 251-260Conference paper (Refereed)
    Abstract [en]

    This paper considers an asynchronous direct-sequence code division multiple access (DS-CDMA) communication system over an AWGN channel. We are interested in estimating the propagation delay from the different users to the receiver. The Cram'er-Rao bound for such an estimator is derived and compared with the measured variance of three algorithms. The performance of the classical correlation-based estimator is demonstrated to be quite good in a noise-limited scenario. However, in a near-far situation, i.e., when the multiple access interference becomes dominant, the performance of the classical method is severely degraded. We therefore propose two new algorithms which are shown to be near-far resistant.

  • 19.
    Zhang, Charlie Jianzhong
    et al.
    Univ Wisconsin, Madison, WI 53706 USA..
    Ma, Jianglei
    Huawei Canada R Ctr, Markham, ON, Canada..
    Li, Geoffrey Ye
    Georgia Tech, Atlanta, GA 30332 USA..
    Kishiyama, Yoshihisa
    Hokkaido Univ, Sapporo, Hokkaido, Japan..
    Parkvall, Stefan
    KTH. Ericsson Res, Kista, Sweden.
    Liu, Guangyi
    China Mobile Res Inst, Wireless & Device Dept, Beijing, Peoples R China..
    Kim, Young-Han
    Univ Calif San Diego, Dept Elect & Comp Engn, La Jolla, CA 92093 USA..
    Key Technology for 5G New Radio2018In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 56, no 3, p. 10-11Article in journal (Refereed)
  • 20. Zhang, Charlie Jianzhong
    et al.
    Ma, Jianglei
    Li, Geoffrey Ye
    Georgia Tech, Sch ECE, Atlanta, GA USA..
    Yu, Wei
    Univ Toronto, Toronto, ON, Canada..
    Jindal, Nihar
    Univ Calif Berkeley, Elet Engn Comp Sci, Berkeley, CA USA..
    Kishiyama, Yoshihisa
    NTT DoCoMo, INC, Toyota, Japan..
    Parkvall, Stefan
    KTH. Royal Inst Technol, Stockholm, Sweden..
    New Waveforms for 5G Networks2016In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 54, no 11, p. 64-65Article in journal (Other academic)
  • 21.
    Östman, Thomas
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    An Improved MUSIC Algorithm for Estimation of Time Delays in Asynchronous DS-CDMA Systems1999In: IEEE Transactions on Communications, ISSN 0090-6778, Vol. 47, no 11, p. 1628-1631Article in journal (Refereed)
    Abstract [en]

    The problem of near–far resistant time-delay estimation in an asynchronous direct-sequence code-division multipleaccess system is considered, and by better exploiting the structureof the problem, estimators superior to previously known techniques are obtained. For a typical numerical example, a gain insignal-to-noise ratio of approximately 3 dB is obtained.

  • 22.
    östman, Thomas
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Parkvall, Stefan
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Improved MUSIC Algorithm for Estimation of Time Delays in Asynchronous DS-CDMA Systems1997In: Proceedings of Asilomar Conference on Signals, Systems & Computers, IEEE , 1997, p. 838-842Conference paper (Refereed)
    Abstract [en]

    An algorithm for time delay estimation in an asynchronous direct-sequence code-division multiple access (DS-CDMA) system which exploits the structure of the system better than previously known algorithms, is presented. The different algorithms are compared through simulation and asymptotic analysis (large number ofvector samples). For a typical scenario it is shown that the proposed algorithm decreases the standard deviationof the time delay errors with a factor of approximately 2.

1 - 22 of 22
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