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  • 1.
    Ahlström, Tobias
    et al.
    Linköpings universitet, Institutionen för systemteknik.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik.
    Superimposed Codes for CDMA over Fiber Optic Channels2004Inngår i: Ninth International Workshop on Algebraic and Combinatorial Coding Theory,2004, 2004, s. 14-19Konferansepaper (Fagfellevurdert)
  • 2.
    Axell, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Capacity Considerations for Uncoordinated Communication in Geographical Spectrum Holes2009Inngår i: Physical Communication, ISSN 1874-4907, Vol. 2, nr 1-2, s. 3-9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cognitive radio is a new concept of reusing a licensed spectrum in an unlicensed manner. The motivation for cognitive radio is various measurements of spectrum utilization, that generally show unused resources in frequency, time and space. These "spectrum holes" could be exploited by cognitive radios. Some studies suggest that the spectrum is extremely underutilized, and that these spectrum holes could provide ten times the capacity of all existing wireless devices together. The spectrum could be reused either during time periods where the primary system is not active, or in geographical positions where the primary system is not operating. In this paper, we deal primarily with the concept of geographical reuse, in a frequency-planned primary network. We perform an analysis of the potential for communication in a geographical spectrum hole, and in particular the achievable sum-rate for a secondary network, to some order of magnitude. Simulation results show that a substantial sum-rate could be achieved if the secondary users communicate over small distances. For a small number of secondary links, the sum-rate increases linearly with the number of links. However, the spectrum hole gets saturated quite fast, due to interference caused by the secondary users. A spectrum hole may look large, but it disappears as soon as someone starts using it.

  • 3.
    Boyvalenkov, P.
    et al.
    Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Sofia, Bulgaria; Faculty of Engineering, South-Western University, Blagoevgrad, Bulgaria.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem.
    Stoyanova, M.
    Faculty of Mathematics and Informatics, Sofia University, Sofia, Bulgaria.
    Refinements of Levenshtein Bounds in q-ary Hamming Spaces2018Inngår i: Problems of Information Transmission, ISSN 0032-9460, E-ISSN 1608-3253, Vol. 54, nr 4, s. 329-342Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We develop refinements of the Levenshtein bound in q-ary Hamming spaces by taking into account the discrete nature of the distances versus the continuous behavior of certain parameters used by Levenshtein. We investigate the first relevant cases and present new bounds. In particular, we derive generalizations and q-ary analogs of the MacEliece bound. Furthermore, we provide evidence that our approach is as good as the complete linear programming and discuss how faster are our calculations. Finally, we present a table with parameters of codes which, if exist, would attain our bounds.

  • 4. Boyvalenkov, Peter
    et al.
    Danev, Danyo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Datatransmission.
    Uniqueness of the 120-point spherical 11-design in four dimensions2001Inngår i: Archiv der Mathematik, ISSN 0003-889X, E-ISSN 1420-8938, Vol. 77, nr 4, s. 360-368Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We prove that on the Euclidean sphere S-3 there exist a unique up to isometry 120-point spherical 11-design and a maximal (4, 120, cos(pi /5)) -code. Both these are nothing but copies of a famous regular polytope in four dimensions-the 600-cell.

  • 5.
    Chandhar, Prabhu
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Massive MIMO as Enabler for Communications with Drone Swarms2016Inngår i: 2016 INTERNATIONAL CONFERENCE ON UNMANNED AIRCRAFT SYSTEMS (ICUAS), IEEE , 2016, s. 347-354Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Massive multiple-input multiple-output (MIMO) is an emerging technology for mobile communications, where a large number of antennas are employed at the base station to simultaneously serve multiple single-antenna terminals with very high capacity. In this paper, we study the potentials and challenges of utilizing massive MIMO for unmanned aerial vehicles (UAVs) communication. We consider a scenario where multiple single-antenna UAVs simultaneously communicate with a ground station (GS) equipped with a large number of antennas. Speci[1]cally, we discuss the achievable uplink (UAV to GS) capacity performance in the case of line-of-sight (LoS) conditions. We also study the type of antenna polarization that should be used in order to maintain a reliable communication link between the GS and the UAVs. The results obtained using a realistic geometric model show that massive MIMO is a potential enabler for high-capacity UAV network

  • 6.
    Chandhar, Prabhu
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Massive MIMO for Communications With Drone Swarms2018Inngår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, nr 3, s. 1604-1629Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We illustrate the potential of Massive MIMO for communication with unmanned aerial vehicles (UAVs). We consider a scenario, where multiple single-antenna UAVs simultaneously communicate with a ground station (GS) equipped with a large number of antennas. Specifically, we discuss the achievable uplink (UAV to GS) capacity performance in the case of line-of-sight conditions. We develop a realistic geometric model, which incorporates an arbitrary orientation, of the GS and UAV antenna elements to characterize the polarization mismatch loss, which occurs due to the movement and orientation of the UAVs. A closed-form expression for a lower bound on the ergodic rate for a maximum-ratio combining receiver with estimated channel state information is derived. The optimal antenna spacing that maximizes the ergodic rate achieved by an UAV is also determined for uniform linear and rectangular arrays. It is shown that when the UAVs are spherically uniformly distributed around the GS, the ergodic rate per UAV is maximized for an antenna spacing equal to an integer multiple of one-half wavelength.

  • 7.
    Chandhar, Prabhu
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    On Ergodic Rates and Optimal Array Geometry in Line-of-Sight Massive MIMO2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We investigate the achievable ergodic rate of Massive multi-input-multi-output (MIMO) system in environments with high mobility and line-of-sight (LoS). A 3-dimensional geometric model with uniform rectangular array at the basestation (BS) is used for the investigation. We derive a closed formexpression for a lower bound on the uplink ergodic rate takinginto account imperfections of the channel state information,number of BS antennas, antenna spacing, and spatial distributionof user terminals. The results show that, in LoS Massive MIMO, when the terminals are spherically uniformly distributed around the BS, the ergodic rate is maximized for antenna spacing equal to integer multiples of one-half wavelength.

  • 8.
    Chandhar, Prabhu
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    On the Zero-Forcing Receiver Performance for Massive MIMO Drone Communications2018Inngår i: 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 930-934Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We study the uplink ergodic rate performance of the zero-forcing (ZF) receiver in a Massive multiple-input and multiple-output (MIMO) enabled drone communication system. Considering a 3D geometric model for line-of-sight (LoS) propagation, approximate but accurate analyses of lower and upper bounds on the uplink ergodic rate with estimated channel state information (CSI) are provided.

  • 9.
    ChengWen, Xing
    et al.
    Beijing Institute of Technology, China .
    ZeSong, Fei
    Beijing Institute of Technology, China .
    Na, Li
    Beijing Institute of Technology, China .
    YanTao, Han
    Beijing Institute of Technology, China .
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    JingMing, Kuang
    Beijing Institute of Technology, China .
    Statistically robust resource allocation for distributed multi-carrier cooperative networks2013Inngår i: Science China Information Sciences, ISSN 1674-733X, Vol. 56, nr 2, s. 109-121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we investigate joint subcarrier and power allocation scheme for distributed multi-carrier cooperative networks with imperfect channel state information. Using practical channel estimation algorithms, the statistic model of the channel estimation error is first derived. Then based on the channel error model, the resource allocation scheme aims at maximizing the sum rate of the overall network. Specifically, both subcarrier allocation and power allocation are taken into account. In the subcarrier allocation, a realistic problem of the power leakage between neighboring subcarriers is also addressed. Furthermore, based on Lagrange dual-decomposition algorithm, a practical power allocation algorithm is proposed. Finally, the simulation results demonstrate the performance advantages of the proposed robust design.

  • 10.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    On Signal Detection Techniques for the DVB-T Standard2010Inngår i: Proceedings of the International Symposium on Communications, Control and Signal Processing (ISCCSP), 2010, s. 1-5Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    In this paper we discuss some spectrum sensing techniques for detection of DVB-T signals. Their performance is compared in terms of probability of detection and ROC curves. Some simulation results are presented for various scenarios.

  • 11.
    Danev, Danyo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Datatransmission.
    Some constructions of superimposed codes in Euclidean spaces2003Inngår i: Discrete Applied Mathematics, ISSN 0166-218X, E-ISSN 1872-6771, Vol. 128, nr 1 SPEC., s. 85-101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We describe three new methods for obtaining superimposed codes in Euclidean spaces. With help of them we construct codes with parameters improving upon known constructions. We also prove that the spherical simplex code is not optimal as superimposed code at least for dimensions greater than 9. © 2003 Elsevier Science B.V. All rights reserved.

  • 12.
    Danev, Danyo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Datatransmission.
    Superimposed Codes in Rn Obtained from Spherical Codes2001Inngår i: Electronic Notes in Discrete Mathematics, ISSN 1571-0653, E-ISSN 1571-0653, Vol. 6, s. 98-106Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We give a sufficient condition for a spherical code to be a (n, d, m, T)-spherical superimposed code. We apply this condition to obtain new spherical superimposed codes with help of known spherical codes and codes in the real projective spaces PRn-1. © 2001.

  • 13.
    Danev, Danyo
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Axell, Erik
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Spectrum Sensing Methods for Detection of DVB-T Signals in AWGN and Fading Channels2010Inngår i: Proceedings of the 21st Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 2010, s. 2721-2726Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we consider spectrum sensing of DVB-T signals in differentfading environments. We compare state-of-the-art detectorsincluding detectors based on pilot subcarriers, as well as detectors for general OFDM signals that exploit the correlation structure incurred by the cyclicprefix. Energy detection is also included for comparison. We shownumerically that the choice of detector depends on the scenario, the detectorrequirements, and on the available prior knowledge. We also show that it ispossible to obtain good detection performance by exploiting the correlation,even in a frequency selective channel.

  • 14.
    Danev, Danyo
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Dodunekov, Stefan
    Bulgarian Academy of Sciences.
    A Family of Ternary Quasi-Perfect BCH Codes2008Inngår i: Designs, Codes and Cryptography, ISSN 0925-1022, E-ISSN 1573-7586, Vol. 49, s. 265-271Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper we present a family of ternary quasi-perfect BCH codes. These codes are of minimum distance 5 and covering radius 3. The first member of this family is the ternary quadratic-residue code of length 13.

  • 15.
    Danev, Danyo
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Institutionen för systemteknik, Datatransmission.
    Dodunekov, Stefan
    A Family of Ternary Quasi-Perfect Codes2007Konferansepaper (Fagfellevurdert)
  • 16.
    Danev, Danyo
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Dodunekov, Stefan
    Bulgarian Academy of Science.
    Radkova, Diana
    Sofia University.
    A family of constacyclic ternary quasi-perfect codes with covering radius 32011Inngår i: DESIGNS CODES AND CRYPTOGRAPHY, ISSN 0925-1022, Vol. 59, nr 1-3, s. 111-118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper a family of constacyclic ternary quasi-perfect linear block codes is presented. This family extends the result presented in a previous work by the first two authors, where the existence of codes with the presented parameters was stated as an open question. The codes have a minimum distance 5 and covering radius 3.

  • 17.
    Danev, Danyo
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Dodunekov, Stefan
    Bulgarian Academy of Sciences, Bulgaria.
    Radkova, Diana
    Sofia University, Bulgaria.
    A Family of Constacyclic Ternary Quasi-Perfect Codes with  Covering Radius 32009Inngår i: Proceedings of the International Workshop on Coding and Cryptography (WCC'09), 2009, s. 111-118Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper a family of constacyclic ternary quasi-perfect linearblock codes is presented. This family extends the result presented ina previous work by the first two authors, where the existence of codeswith the presented parameters was stated as an open question. The codes have a minimum distance 5 and covering radius 3.

  • 18.
    Danev, Danyo
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Datatransmission.
    Füredi, Zoltán
    Ruszinkó, Miklós
    Multiple Access Euclidean Channel2007Inngår i: Multiple Access Channels - Theory and Practice / [ed] Ezio Biglieri and László Györfi, Amsterdam: IOS Press , 2007, s. 54-72Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    While multiple-access communication dates back to systems invented in the 1870's to transmit simultaneous data through a single wire, the foundation of the discipline now known as 'multiuser information theory' was laid in 1961, when Claude E. Shannon published his paper on two-way channels. Since then, multiuser information theory has been an extremely active research area, and has seen a large number of fundamental contributions, covering, besides the two-way channel studied in, multiple access, interference, broadcast, and wiretap channels. However, several key canonical problems have defied many efforts. This book brings together leading experts working in the fields of information theory, coding theory, multiple user communications, discrete mathematics, etc., who survey recent and general results on multiple-access channels (rate regions, rate splitting, etc.), and give an overview of the problems of current CDMA solutions (fading channels, multi-user detection, multiple-antenna systems, iterative joint decoding, OFDMA, etc.). This publication consist of three parts. The first part includes chapters devoted to the information-theoretical aspects of multiple-access communication. In the second part, multiple-access techniques are discussed and the third part of this volume covers coding techniques

  • 19.
    Danev, Danyo
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Institutionen för systemteknik, Datatransmission.
    Grimnell, Mikael
    Tjäder, Mats
    Tullberg, Hugo
    Efficient Message-Passing Decoding of LDPC Codes using Vector-based Messages2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we investigate reduced complexitydecoders for LDPC codes over M-PSK modulation. Capacitycalculations show only minor losses if only phase informationis considered in the decoder. We device a decoder based onphase angle summation, which unfortunately does not work forcodes over Galois fields (but shows promising results for codesover integer rings). For codes over Galois Fields we constructtable-based decoders which gives performance close to BeliefPropagation decoders at substantially reduced complexity.

  • 20.
    Danev, Danyo
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Datatransmission.
    Olsson, Jonas
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik.
    On a sequence of cyclic codes with minimum distance six2000Inngår i: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 46, nr 2, s. 673-674Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A sequence of q-ary cyclic codes is analyzed. For each finite field GF (q), q=4, there is a code with parameters [n, k, d, q] = [q(q-1)+1, q(q-1)-6, 6,q]. All these codes are n-, k-, and d-optimal, with only one exception. The dual codes are considered. Their true minimum distances are calculated in the range 4=q=32.

  • 21.
    Danev, Danyo
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Datatransmission.
    Puaca, Daniel
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Datatransmission.
    New majority logic decoding algorithm for Reed-Muller codes2007Inngår i: International Workshop on Optimal Codes and Related Topics,2007, 2007, s. 203-208Konferansepaper (Fagfellevurdert)
  • 22.
    Danev, Danyo
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Datatransmission.
    Ruszinkó, Miklós
    Laczay, Bálint
    Multiple Access Adder Channel2007Inngår i: Multiple Access Channels - Theory and Practice / [ed] Ezio Biglieri and László Györfi, Amsterdam: IOS Press , 2007, s. 26-53Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    While multiple-access communication dates back to systems invented in the 1870's to transmit simultaneous data through a single wire, the foundation of the discipline now known as 'multiuser information theory' was laid in 1961, when Claude E. Shannon published his paper on two-way channels. Since then, multiuser information theory has been an extremely active research area, and has seen a large number of fundamental contributions, covering, besides the two-way channel studied in, multiple access, interference, broadcast, and wiretap channels. However, several key canonical problems have defied many efforts. This book brings together leading experts working in the fields of information theory, coding theory, multiple user communications, discrete mathematics, etc., who survey recent and general results on multiple-access channels (rate regions, rate splitting, etc.), and give an overview of the problems of current CDMA solutions (fading channels, multi-user detection, multiple-antenna systems, iterative joint decoding, OFDMA, etc.). This publication consist of three parts. The first part includes chapters devoted to the information-theoretical aspects of multiple-access communication. In the second part, multiple-access techniques are discussed and the third part of this volume covers coding techniques

  • 23.
    Jorswieck, Eduard A.
    et al.
    Dresden University of Technology.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Complete Characterization of the Pareto Boundary for the MISO Interference Channel2008Inngår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 56, nr 10, s. 5292-5296Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this correspondence, we study the achievable rate region of the multiple-input single-output (MISO) interference channel, under the assumption that all receivers treat the interference as additive Gaussian noise. Our main result is an explicit parametrization of the Pareto boundary for an arbitrary number of users and antennas. The parametrization describes the boundary in terms of a low-dimensional manifold. For the two-user case we show that a single real-valued parameter per user is sufficient to achieve all points on the Pareto boundary and that any point on the Pareto boundary corresponds to beamforming vectors that are linear combinations of the zero-forcing (ZF) and maximum-ratio transmission (MRT) beamformers. We further specialize the results to the MISO broadcast channel (BC). A numerical example illustrates the result.

  • 24.
    Larsson, Erik G.
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Accuracy Comparison of LS and Squared-Range LS for Source Localization2010Inngår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 58, nr 2, s. 916-923Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this correspondence we compute a closed-form expression for theasymptotic (large-sample) accuracy of the recently proposedsquared-range least-squares (SR-LS) method for source localization. We compare its accuracy to that of the classicalleast-squares (LS) method and show that LS and SR-LS performdifferently in general. We identify geometries where theperformances of the methods are identical but also geometries when thedifference in performance is unbounded.

  • 25.
    Larsson, Erik G.
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Jorswieck, Eduard A.
    Dresden University of Technology.
    Asymptotically Optimal Transmit Strategies for the Multiple Antenna Interference Channel2008Inngår i: Proceedings of the 46th Annual Allerton Conference on Communication, Control, and Computing (Allerton'08), 2008, s. 708-714Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider the interference channel with multiple antennas at the transmitter. We prove that at high signal-to-noise ratio (SNR), the zero-forcing transmit scheme is optimal in the sum-rate sense. Furthermore we prove that at low SNR, maximum-ratio transmission is optimal in the sum-rate sense. We also provide a discussion of the connection to classical results on spectral efficiency in the wideband regime. Finally, we propose a non-convex optimization approach based on monotonic optimization to solve the sum rate maximization problem.

  • 26.
    Larsson, Erik G.
    et al.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten. University of Sofia, Bulgaria.
    Olofsson, Mikael
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Sörman, Simon
    Ericsson Res, Linkoping, Sweden.
    Teaching the Principles of Massive MIMO: Exploring reciprocity-based multiuser MIMO beamforming using acoustic waves2017Inngår i: IEEE signal processing magazine (Print), ISSN 1053-5888, E-ISSN 1558-0792, Vol. 34, nr 1, s. 40-47Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Massive multiple-input, multiple-output (MIMO) is currently the most compelling wireless physical layer technology and a key component of fifth-generation (5G) systems. The understanding of its core principles has emerged during the last five years, and material is becoming available that is rigorously refined to focus on timeless fundamentals [1], facilitating the instruction of the topic to both master- and doctoral-level students [2]. Meaningful laboratory work that exposes the operational principles of massive MIMO is more difficult to accomplish. At Linköping University, Sweden, this was achieved through a project course, based on the conceive-design-implement-operate (CDIO) concept [3], and through the creation of a specially designed experimental setup using acoustic signals.

  • 27.
    Roth, Stefan
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Jiansong, Gan
    Ericsson Research, Beijing, China.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Subframe allocation for relay networks in the LTE advanced standard2010Inngår i: Proceedings of IEEE 21st International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), 2010, 2010, s. 1758-1763Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The use of relays is a promising way to extend coverage and increase rates in Long Term Evolution Advanced (LTE Advanced) networks. Performing a transmission in several hops (BS-relay & relay-user) requires more radio resources than a single hop transmission. This paper analyses how the available radio resource should be allocated between relays and users in order to maximize throughput and/or fairness. Time and frequency multiplexed backhaul is investigated under some basic assumptions on the division of the radio resource. It is shown that the system will typically be backhaul limited and that the two ways of multiplexing will perform equally when fairness is taken into account. The analysis results in throughput/fairness suboptimal solutions, dependant on the number of relays per cell, spectral efficiencies and fraction of users served by relays. The analysis is verified by simulations, performed using a MATLAB based network simulator.

  • 28.
    Tumula V.K., Chaitanya
    et al.
    McGill Univ., Canada.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Larsson, Erik G
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Constant envelope signal space diversity2014Inngår i: Proceedings of the 2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), IEEE conference proceedings, 2014, s. 3147-3151Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose a nonlinear signal space diversity (SSD) precoding techniquethat produces transmit signals that have constant envelope(CE) in discrete time, resulting in low peak-to-average power ratio(PAPR) waveforms after pulse-shape filtering. We propose twomethods for construction of CE signal set. While the proposed CESSDscheme is inferior to the conventional SSD designs in termsof coding gain performance, it performs better in terms of overallpower efficiency because of the reduced back-off requirement of thepower amplifier (PA).

  • 29.
    Wu, Yi
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Improved Detection of ACK/NACK Messages in the LTE Uplink Control Channel2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we present an improved detector for ACK/NACK message detection in the LTE uplink control channel with imperfect channel state information at the receiver. The detector is based on the generalized likelihood-ratio test (GLRT) paradigm. We derive detection metrics for the cases when the noise variances at the receiver are known and unknown. Noise here may comprise both thermal noise and interference. Simulation results show remarkable performance gains of the GLRT-based detector with unknown noise variances compared to the training-based maximum-likelihood detector with unknown noise variances when the noise variances in two slots are different. Furthermore, the performance of the GLRT-based detector with unknown noise variances is nearly the same as that of the training-based maximum-likelihood detector with known noise variances.

  • 30.
    Wu, Yi
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    On ACK/NACK messages detection in the LTE PUCCH with multiple receive antennas2012Inngår i: Signal Processing Conference (EUSIPCO), 2012, IEEE COMPUTER SOC , 2012, s. 994-998Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we study ACK/NACK messages detection in the LTE physical uplink control channel (PUCCH) with multiple receive antennas. The LTE PUCCH is typically characterized by high interference variability due to severe inter-user interferences and slot-level frequency hopping. We present detection methods applicable for the cases when the noise variances at the receiver are known and unknown. Noise here may comprise both thermal noise and interference. The proposed detection technique is based on the generalized likelihood-ratio test (GLRT) paradigm. Simulation results show that GLRT-based detector offers a significant gain over the training-based maximum-likelihood detector when the noise variances in two slots are different and unknown. For the case when the noise variances at the receiver are known, the GLRT-based detector has nearly the same performance as the training-based maximum-likelihood detector.

  • 31.
    ZeSong, Fei
    et al.
    Beijing Institute of Technology, China.
    ChengWen, Xing
    Beijing Institute of Technology, China.
    Na, Li
    Beijing Institute of Technology, China.
    YanTao, Han
    Beijing Institute of Technology, China.
    Danev, Danyo
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    JingMing, Kuang
    Beijing Institute of Technology, China.
    Power allocation for OFDM-based cognitive heterogeneous networks2013Inngår i: Science China Information Sciences, ISSN 1674-733X, Vol. 56, nr 4, s. 1-10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, the capacity maximization and the spectrum utilization efficiency improvement are investigated for the Pico cells in broadband heterogeneous networks. In frequency-reuse model, the users attached to Macro base station are usually viewed as primary users, and those attached to Pico base station should be regarded as cognitive radio (CR) users. As both the primary users and the CR users communicate in parallel frequency bands, the performance of the system is limited by the mutual inter-carrier interference (ICI). In order to control ICI and maximize the achievable transmission rate of the CR users, an effective power allocation scheme is proposed to maximize the transmission rate of the CR users under a given interference threshold prescribed by the primary users. By transforming this suboptimal solution into an innovative matrix expression, the algorithm is easier to perform in practice. The simulation results demonstrate that the proposed algorithm provides a large performance gain in Pico cell capacity over the non-cooperative and equal power allocation schemes.

1 - 31 of 31
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