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  • 1.
    Ainomae, Ahti
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Bengtsson, Mats
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Trump, Tonu
    Tallinn Univ Technol, Dept Radio & Telecommun Engn, EE-12616 Tallinn, Estonia..
    Distributed Largest Eigenvalue-Based Spectrum Sensing Using Diffusion LMS2018In: IEEE TRANSACTIONS ON SIGNAL AND INFORMATION PROCESSING OVER NETWORKS, ISSN 2373-776X, Vol. 4, no 2, p. 362-377Article in journal (Refereed)
    Abstract [en]

    In this paper, we propose a distributed detection scheme for cognitive radio (CR) networks, based on the largest eigenvalues (LEs) of adaptively estimated correlation matrices (CMs), assuming that the primary user signal is temporally correlated. The proposed algorithm is fully distributed, there by avoiding the potential single point of failure that a fusion center would imply. Different forms of diffusion least mean square algorithms are used for estimating and averaging the CMs over the CR network for the LE detection and the resulting estimation performance is analyzed using a common framework. In order to obtain analytic results on the detection performance, the exact distribution of the CM estimates are approximated by a Wishart distribution, by matching the moments. The theoretical findings are verified through simulations.

  • 2.
    Alizadeh, Mahmoud
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. University of Gävle.
    Characterisation, Modelling and Digital Pre-DistortionTechniques for RF Transmitters in Wireless Systems2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wireless systems have become an inevitable part of modern technologies serving humankind. The rapid growth towards large dimensional systems, e.g. 5th generation (5G) technologies, incurs needs for improving the performance of the systems and considering aspects to make them as far as possible environmentally friendly in terms of power efficiency, cost, and so on. One of the key parts of every wireless communication system is the radio frequency (RF) power amplifier (PA), which consumes the largest percentage of the total energy. Hence, accurate models of RF PAs can be used to optimize their design and to compensate for signal distortions. This thesis starts with two methods for frequency-domain characterisation to analyse the dynamic behaviour of PAs in 3rd-order non-linear systems. Firstly, two-tone signals superimposed on large-signals are used to analyse the frequency-domain symmetry properties of inter-modulation (IM) distortions and Volterra kernels in different dynamic regions of RF PAs in a single-input single-output (SISO) system. Secondly, three-tone signals are used to characterise the 3rd-order self- and cross-Volterra kernels of RF PAs in a 3 × 3 multiple-input multiple-output (MIMO) system. The main block structures of the models are determined by analysing the frequency-domain symmetry properties of the Volterra kernels in different three-dimensional (3D) frequency spaces. This approach significantly simplifies the structure of the 3rd-order non-linear MIMO model.

    The following parts of the thesis investigate techniques for behavioural modelling and linearising RF PAs. A piece-wise modelling technique is proposed to characterise the dynamic behaviour and to mitigate the impairments of non-linear RF PAs at different operating points (regions). A set of thresholds decompose the input signal into several sub-signals that drive the RF PAs at different operating points. At each operating point, the PAs are modelled by one sub-model, and hence, the complete model consists of several sub-models. The proposed technique reduces the model errors compared to conventional piece-wise modelling techniques.

    A block structure modelling technique is proposed for RF PAs in a MIMO system based on the results of the three-tone characterisation technique. The main structures of the 3rd- and higher-order systems are formulated based on the frequency dependence of each block. Hence, the model can describe more relevant interconnections between the inputs and outputs than conventional polynomial-type models.

    This thesis studies the behavioural modelling and compensation techniques in both the time and the frequency domains for RF PAs in a 3 × 3MIMO system. The 3D time-domain technique is an extension of conventional 2D generalised memory polynomial (GMP) techniques. To reduce the computational complexity, a frequency-domain technique is proposed that is efficient and feasible for systems with long memory effects. In this technique, the parameters of the model are estimated within narrow sub-bands. Each sub-band requires only a few parameters, and hence the size of the model for each sub-band is reduced.

  • 3.
    Alizadeh, Mahmoud
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. University of Gävle.
    Händel, Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Rönnow, Daniel
    University of Gävle.
    Basis Function Decomposition Approach in Piece-Wise Modeling for RF Power Amplifiers2018In: 6th Telecommunications forum TELFOR 2018, Belgrade, Serbia, 2018Conference paper (Refereed)
    Abstract [en]

    In this paper, a new approach is proposed to decompose the basis functions in a piece-wise modeling technique for nonlinear radio frequency (RF) power amplifiers. The proposed technique treats the discontinuity problem of the model output at the joint points between different operating points, whereas preserves the linear and nonlinear properties of the original model within each region. Experimental results show that the proposed technique outperforms the conventional piece-wise model in terms of model errors.

  • 4.
    Alizadeh, Mahmoud
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. Univ Gavle, Dept Elect Math & Nat Sci, SE-80176 Gavle, Sweden..
    Händel, Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Rönnow, Daniel
    Univ Gavle, Dept Elect Math & Nat Sci, SE-80176 Gavle, Sweden..
    Basis Function Decomposition Approach in Piece-Wise Modeling for RF Power Amplifiers2018In: 2018 26TH TELECOMMUNICATIONS FORUM (TELFOR), IEEE , 2018, p. 140-143Conference paper (Refereed)
    Abstract [en]

    In this paper a new approach is proposed to decompose the basis functions in a piece-wise modeling technique for nonlinear radio frequency (RF) power amplifiers. The proposed technique treats the discontinuity problem of the model output at the joint points between different operating points, whereas preserves the linear and nonlinear properties of the original model within each region. Experimental results show that the proposed technique outperforms the conventional piece-wise model in terms of model errors.

  • 5.
    Alizadeh, Mahmoud
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. University of Gävle.
    Händel, Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Rönnow, Daniel
    University of Gävle.
    Behavioural modelling and digital pre-distortion techniques for RF PAs in a 3x3 MIMO system2018In: International journal of microwave and wireless technologies, ISSN 1759-0795, E-ISSN 1759-0787Article in journal (Refereed)
    Abstract [en]

    Modern telecommunications are moving towards (massive) multi-input multi-output systems in 5th generation (5G) technology, increasing the dimensionality of the system dramatically. In this paper, the impairments of radio frequency (RF)power amplifiers (PAs) in a 3x3 MIMO system are compensated in both time and frequency domains. A three-dimensional(3D) time-domain memory polynomial-type model is proposed as an extension of conventional 2D models. Furthermore, a 3D frequency-domain technique is formulated based on the proposed time-domain model to reduce the dimensionality of the model, while preserving the performance in terms of model errors. In the 3D frequency-domain technique, the bandwidth of a system is split into several narrow sub-bands, and the parameters of the system are estimated for each subband. This approach requires less computational complexity, and also the procedure of the parameters estimation for each sub-band can be implemented independently. The device-under-test (DUT) consists of three RF PAs including input and output cross-talk channels. The proposed techniques are evaluated in both behavioural modelling and digital pre-distortion(DPD) perspectives. The results show that the proposed DPD technique can compensate the errors of non-linearity and memory effects by about 23.5 dB and 7 dB in terms of the normalized mean square error and adjacent channel leakage ratio, respectively.

  • 6.
    Alizadeh, Mahmoud
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. Department of Electronics, Mathematics and Natural Sciences, University of Gävle (HiG), Gävle, Sweden.
    Rönnow, D.
    Händel, Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Characterization of Volterra Kernels for RF Power Amplifiers Using a Two-Tone Signal and a Large-Signal2018In: 2018 12th International Conference on Communications, COMM 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 351-356, article id 8430119Conference paper (Refereed)
    Abstract [en]

    The 3rd-order Volterra kernels of a radio frequency (RF) power amplifier (PA) are characterized using a large-signal and a two-tone probing-signal. In this technique, the magnitude and phase asymmetries of the kernels of the PA excited by the probing-signal are analyzed in different amplitude regions of the large-signal. The device under test is a class-AB PA operating at 2.14 GHz. The maximum sweeping frequency space of the probing-signal is 20 MHz. The results indicate that the Volterra kernels of the PA show different behaviors (frequency dependency and asymmetry) in different regions.

  • 7.
    Alizadeh, Mahmoud
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. University of Gävle.
    Rönnow, Daniel
    University of Gävle.
    Händel, Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    A new Block-Structure Modeling Technique for RF Power Amplifiers in a 2×2 MIMO System2017In: 2017 13th International Conference on Advanced Technologies, Systems and Services in Telecommunications, TELSIKS 2017 - Proceeding, Nis, Serbia: IEEE, 2017, Vol. 2017, p. 224-227Conference paper (Refereed)
    Abstract [en]

    A new block-structure behavioral model is proposed for radio frequency power amplifiers in a 2×2 multiple-input multiple-output system including input cross-talk. The proposed model forms kernels of blocks of different nonlinear order that correspond to the significant frequency response of measured frequency domain Volterra kernels. The model can therefore well describe the input-output relationships of the nonlinear dynamic behavior of PAs. The proposed model outperforms conventional models in terms of model errors.

  • 8.
    Avula, Ramana R.
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Månsson, Daniel
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Privacy-preserving smart meter control strategy including energy storage losses2018In: Proceedings - 2018 IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT-Europe 2018, Institute of Electrical and Electronics Engineers (IEEE), 2018, article id 8571537Conference paper (Refereed)
    Abstract [en]

    Privacy-preserving smart meter control strategies proposed in the literature so far make some ideal assumptions such as instantaneous control without delay, lossless energy storage systems etc. In this paper, we present a one-step-ahead predictive control strategy using Bayesian risk to measure and control privacy leakage with an energy storage system. The controller estimates energy state using a three-circuit energy storage model to account for steady-state energy losses. With numerical experiments, the controller is evaluated with real household consumption data using a state-of-the-art adversarial algorithm. Results show that the state estimation of the energy storage system significantly affects the controller's performance. The results also show that the privacy leakage can be effectively reduced using an energy storage system but at the expense of energy loss.

  • 9.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Ghauch, Hadi
    Fodor, Gabor
    Skoglund, Mikael
    KTH, Superseded Departments (pre-2005), Signals, Sensors and Systems. KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Smart Antenna Assignment is Essential in Full-Duplex Communications2019In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857Article in journal (Refereed)
    Abstract [en]

    Full-duplex communications have the potential to almost double the spectralefficiency. To realize such a potentiality, the signal separation at base station’s antennasplays an essential role. This paper addresses the fundamentals of such separationby proposing a new smart antenna architecture that allows every antenna to beeither shared or separated between uplink and downlink transmissions. The benefitsof such architecture are investigated by an assignment problem to optimally assignantennas, beamforming and power to maximize the weighted sum spectral efficiency.We propose a near-to-optimal solution using block coordinate descent that divides theproblem into assignment problems, which are NP-hard, a beamforming and powerallocation problems. The optimal solutions for the beamforming and power allocationare established while near-to-optimal solutions to the assignment problems are derivedby semidefinite relaxation. Numerical results indicate that the proposed solution isclose to the optimum, and it maintains a similar performance for high and low residualself-interference powers. With respect to the usually assumed antenna separationtechnique and half-duplex transmission, the sum spectral efficiency gains increase withthe number of antennas. We conclude that our proposed smart antenna assignment forsignal separation is essential to realize the benefits of multiple antenna full-duplexcommunications.

  • 10.
    Bao, Jinchen
    et al.
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 611756, Sichuan, Peoples R China..
    Ma, Zheng
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 611756, Sichuan, Peoples R China..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Tsiftsis, Theodoros A.
    Jinan Univ, Sch Elect & Informat Engn, Zhuhai 519070, Peoples R China..
    Zhu, Zhongliang
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 611756, Sichuan, Peoples R China..
    Bit-Interleaved Coded SCMA With Iterative Multiuser Detection: Multidimensional Constellations Design2018In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 66, no 11, p. 5292-5304Article in journal (Refereed)
    Abstract [en]

    This paper investigates the constellation/codebook design of a promising uplink multiple access technique, sparse code multiple access (SCMA), proposed for the fifth generation mobile networks. The application of bit-interleaved coded modulation with iterative multiuser detection is considered for uplink SCMA over fading channels. Extrinsic information transfer chart is used to aid the analysis and the design of multidimensional constellations, and the design criteria for multidimensional constellations and labelings optimization are thus established. Furthermore, a new and simple approach of multi-stage optimization for the multidimensional constellation design is proposed for SCMA, to improve the bit-error rate performance and alleviate the complexity of turbo multiuser detection. Numerical and simulation results are also provided to demonstrate the performance and verify the efficiency of the proposed scheme, compared with the state of the art.

  • 11.
    Bassi, Germán
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Piantanida, Pablo
    Lossy Communication Subject to Statistical Parameter Privacy2018In: 2018 IEEE International Symposium on Information Theory (ISIT) - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 1031-1035, article id 8437690Conference paper (Refereed)
    Abstract [en]

    We investigate the problem of sharing (communi-cating) the outcomes of a memoryless source when some of its statistical parameters must be kept private. Privacy is measured in terms of the Bayesian statistical risk according to a desired loss function while the quality of the reconstruction is measured by the average per-letter distortion. We first bound -uniformly over all possible estimators- the expected risk from below. This information-theoretic bound depends on the mutual information between the parameters and the disclosed (noisy) samples. We then present an achievable scheme that guarantees an upper bound on the average distortion while keeping the risk above a desired threshold, even when the length of the sample increases.

  • 12.
    Bassi, German
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. Univ Paris Sud, CNRS, Cent Supelec, Lab Signaux & Syst,L2S,UMR 8506, F-91192 Gif Sur Yvette, France.
    Piantanida, Pablo
    Shamai (Shitz), Shlomo
    The Wiretap Channel With Generalized Feedback: Secure Communication and Key Generation2019In: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 65, no 4, p. 2213-2233Article in journal (Refereed)
    Abstract [en]

    It is a well-known fact that feedback does not increase the capacity of point-to-point memoryless channels, however, its effect in secure communications is not fully understood yet. In this paper, an achievable scheme for the wiretap channel with generalized feedback is presented. This scheme, which uses the feedback signal to generate a shared secret key between the legitimate users, encrypts the message to be sent at the bit level. New capacity results for a class of channels are provided, as well as some new insights into the secret key agreement problem. Moreover, this scheme recovers previously reported rate regions from the literature, and thus it can be seen as a generalization that unifies several results in the field.

  • 13.
    Cao, Le Phuong
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Optimal Transmit Strategies for Multi-antenna Systems with Joint Sum and Per-antenna Power Constraints2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nowadays, wireless communications have become an essential part of our daily life. During the last decade, both the number of users and their demands for wireless data have tremendously increased. Multi-antenna communication is a promising solution to meet this ever-growing traffic demands. In this dissertation, we study the optimal transmit strategies for multi-antenna systems with advanced power constraints, in particular joint sum and per-antenna power constraints. We focus on three different models including multi-antenna point-to-point channels, wiretap channels and massive multiple-input multiple-output (MIMO) setups. The solutions are provided either in closed-form or efficient iterative algorithms, which are ready to be implemented in practical systems.

    The first part is concerned with the optimal transmit strategies for point-to-point multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) channels with joint sum and per-antenna power constraints. For the Gaussian MISO channels, a closed-form characterization of an optimal beamforming strategy is derived. It is shown that we can always find an optimal beamforming transmit strategy that allocates the maximal sum power with phases matched to the complex channel coefficients. An interesting property of the optimal power allocation is that whenever the optimal power allocation of the corresponding problem with sum power constraint only exceeds per-antenna power constraints, it is optimal to allocate maximal per-antenna power to those antennas to satisfy the per-antenna power constraints. The remaining power is distributed among the other antennas whose optimal allocation follows from a reduced joint sum and per-antenna power constraints problem with fewer channel coefficients and a reduced sum power constraint. For the Gaussian MIMO channels, it is shown that if an unconstraint optimal power allocation for an antenna exceeds a per-antenna power constraint, then the maximal power for this antenna is used in the constraint optimal transmit strategy. This observation is then used in an iterative algorithm to compute the optimal transmit strategy in closed-form.

    In the second part of the thesis, we investigate the optimal transmit strategies for Gaussian MISO wiretap channels. Motivated by the fact that the non-secure capacity of the MISO wiretap channels is usually larger than the secrecy capacity, we study the optimal trade-off between those two rates with different power constraint settings, in particular, sum power constraint only, per-antenna power constraints only, and joint sum and per-antenna power constraints. To characterize the boundary of the optimal rate region, which describes the optimal trade-off between non-secure transmission and secrecy rates, related problems to find optimal transmit strategies that maximize the weighted rate sum with different power constraints are derived. Since these problems are not necessarily convex, equivalent problem formulation is used to derive optimal transmit strategies. A closed-formsolution is provided for sum power constraint only problem. Under per-antenna power constraints, necessary conditions to find the optimal power allocation are provided. Sufficient conditions, however, are available for the case of two transmit antennas only. For the special case of parallel channels, the optimal transmit strategies can deduced from an equivalent point-to-point channel problem. In this case, there is no trade-off between secrecy and non-secrecy rate, i.e., there is onlya transmit strategy that maximizes both rates.

    Finally, the optimal transmit strategies for large-scale MISO and massive MIMO systems with sub-connected hybrid analog-digital beamforming architecture, RF chain and per-antenna power constraints are studied. The system is configured such that each RF chain serves a group of antennas. For the large-scale MISO system, necessary and sufficient conditions to design the optimal digital and analog precoders are provided. It is optimal that the phase at each antenna is matched tothe channel so that we have constructive alignment. Unfortunately, for the massive MIMO system, only necessary conditions are provided. The necessary conditions to design the digital precoder are established based on a generalized water-filling and joint sum and per-antenna optimal power allocation solution, while the analog precoder is based on a per-antenna power allocation solution only. Further, we provide the optimal power allocation for sub-connected setups based on two properties: (i) Each RF chain uses full power and (ii) if the optimal power allocation of the unconstraint problem violates a per-antenna power constraint then it is optimal to allocate the maximal power for that antenna. The results in the dissertation demonstrate that future wireless networks can achieved higher data rates with less power consumption. The designs of optimal transmit strategies provided in this dissertation are valuable for ongoing implementations in future wireless networks. The insights offered through the analysis and design of the optimal transmit strategies in the dissertation also provide the understanding of the optimal power allocation on practical multi-antenna systems.

  • 14.
    Cao, Le Phuong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Transmit Beamforming for Single-User Large-Scale MISO Systems With Sub-Connected Architecture and Power Constraints2018In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 22, no 10, p. 2096-2099Article in journal (Refereed)
    Abstract [en]

    This letter considers optimal transmit beamforming for a sub-connected large-scale MISO system with RF chain and per-antenna power constraints. The system is configured such that each RF chain serves a group of antennas. For the hybrid scheme, necessary and sufficient conditions to design the optimal digital and analog precoders are provided. It is shown that, in the optimum, the optimal phase shift at each antenna has to match the channel coefficient and the phase of the digital precoder. In addition, an iterative algorithm is provided to find the optimal power allocation. We study the case where the power constraint on each RF chain is smaller than the sum of the corresponding per-antenna power constraints. Then, the optimal power is allocated based on two properties: each RF chain uses full power and if the optimal power allocation of the unconstraint problem violates a per-antenna power constraint then it is optimal to allocate the maximal power for that antenna.

  • 15.
    Cao, Phuong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Optimal Transmit Strategies for Gaussian MISO Wiretap Channels2018In: IEEE Transactions on Information Forensics and Security, ISSN 1556-6013, E-ISSN 1556-6021Article in journal (Other academic)
    Abstract [en]

    This paper studies the optimal tradeoff between secrecy and non-secrecy rates of the MISO wiretap channels for different power constraint settings:sum power constraint only, per-antenna power constraints only and joint sum and per-antenna power constraints. The problem is motivated by the fact thatchannel capacity and secrecy capacity are generally achieved by different transmit strategies. First, a necessary and sufficient condition to ensure a positive secrecy capacity is shown. The optimal tradeoff between secrecy rate and transmission rate is characterized by a weighted rate sum maximization problem. Since this problem is not necessarily convex, equivalent problem formulations are introduced to derive the optimal transmit strategies. Under sum power constraint only, a closed-form solution is provided. Under per-antenna power constraints, necessary conditions to find the optimal power allocation are provided. Sufficient conditions are provided for the special case of two transmit antennas. For the special case of parallel channels, the optimal transmit strategies can deduced from an equivalent point-to-point channel problem. Lastly, the theoretical results are illustrated by numerical simulations.

  • 16.
    Cavarec, Baptiste
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. KTH Royal Inst Technol, Dept Informat Sci & Engn, Sch Elect Engn, Stockholm, Sweden..
    Bengtsson, Mats
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. KTH Royal Inst Technol, Dept Informat Sci & Engn, Sch Elect Engn, Stockholm, Sweden..
    CHANNEL DEPENDENT CODEBOOK DESIGN IN SPATIAL MODULATION2018In: 2018 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH AND SIGNAL PROCESSING (ICASSP), IEEE, 2018, p. 6413-6417Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a modulation design based on Spatial Modulation for the uplink in IoT applications. The proposed modulation design uses a Tabu search based deterministic heuristic to adapt the modulation link based on channel information fed back by the receiver. Our approach allows adaptivity to rate and energy constraints. We numerically validate the proposed method on a scenario with full channel state information available at the transceiver, showing clear performance gains compared to simpler heuristics and channel independent codebook designs.

  • 17.
    Celebi, Hasan Basri
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Pitarokoilis, Antonios
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Training-assisted channel estimation for low-complexity squared-envelope receivers2018In: 2018 IEEE 19TH INTERNATIONAL WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS (SPAWC), IEEE , 2018, p. 196-200Conference paper (Refereed)
    Abstract [en]

    Squared-envelope receivers, also known as energy detectors, are, due to their simplified circuitry, low-cost and low-complexity receivers. Hence they are attractive implementation structures for future Internet-of-Things (IoT) applications. Even though there is considerable work on the wider research area of squared-envelope receivers, a comprehensive comparison and statistical characterization of training-assisted channel estimators for squared-envelope receivers appear to be absent from the literature. A detailed description of practical channel estimation schemes is necessary for the optimal training design of latency-constrained IoT applications. In this paper, various channel estimators are derived, their bias and variance are studied, and their performance is numerically compared against the Cramer-Rao lower bound.

  • 18.
    Celebi, Hasan Basri
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Pitarokoilis, Antonios
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Training-Assisted Channel Estimation for Low-Complexity Squared-Envelope Receivers2018In: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC, Institute of Electrical and Electronics Engineers Inc. , 2018Conference paper (Refereed)
    Abstract [en]

    Squared-envelope receivers, also known as energy detectors, are, due to their simplified circuitry, low-cost and low-complexity receivers. Hence they are attractive implementation structures for future Internet-of-Things (IoT) applications. Even though there is considerable work on the wider research area of squared-envelope receivers, a comprehensive comparison and statistical characterization of training-assisted channel estimators for squared-envelope receivers appear to be absent from the literature. A detailed description of practical channel estimation schemes is necessary for the optimal training design of latency-constrained IoT applications. In this paper, various channel estimators are derived, their bias and variance are studied, and their performance is numerically compared against the Cramer-Rao lower bound.

  • 19.
    Champati, Jaya
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Al-Zubaidy, Hussein
    Gross, James
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Statistical Guarantee Optimization for Age of Information for the D/G/1 Queue2018Conference paper (Refereed)
    Abstract [en]

    Age of Information (AoI) has proven to be a useful metric in networked systems where timely information updates are of importance. Recently, minimizing the “average age” has received considerable attention. However, various applications pose stricter age requirements on the updates which demand knowledge of the AoI distribution. In this work, we study the distribution of the AoI and devise a problem of minimizing the tail of the AoI distribution function with respect to the frequency of generating information updates, i.e., the sampling rate of monitoring a process, for the D/G/1 queue model under FCFS queuing discipline. We argue that computing an exact expression for the AoI distribution may not always be feasible. Therefore, we opt for computing a bound on the tail of the AoI distribution and use it to formulate a tractable α-relaxed Upper Bound Minimization Problem (α-UBMP), where α > 1 is an approximation factor. This approximation can be used to obtain “good” heuristic solutions. We demonstrate the efficacy of our approach by solving α-UBMP for the D/M/1 queue. We show, using simulation, that the rate solutions obtained are near optimal for minimizing the tail of the AoI distribution.

  • 20.
    Champati, Jaya Prakash
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Al-Zubaidy, H.
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Statistical guarantee optimization for age of information for the D/G/1 queue2018In: INFOCOM 2018 - IEEE Conference on Computer Communications Workshops, Institute of Electrical and Electronics Engineers Inc. , 2018, p. 130-135Conference paper (Refereed)
    Abstract [en]

    Age of Information (AoI) has proven to be a useful metric in networked systems where timely information updates are of importance. Recently, minimizing the 'average age' has received considerable attention. However, various applications pose stricter age requirements on the updates which demand knowledge of the AoI distribution. In this work, we study the distribution of the AoI and devise a problem of minimizing the tail of the AoI distribution function with respect to the frequency of generating information updates, i.e., the sampling rate of monitoring a process, for the D/G/1 queue model under FCFS queuing discipline. We argue that computing an exact expression for the AoI distribution may not always be feasible. Therefore, we opt for computing a bound on the tail of the AoI distribution and use it to formulate a tractable a-relaxed Upper Bound Minimization Problem (a-UBMP), where a > 1 is an approximation factor. This approximation can be used to obtain 'good' heuristic solutions. We demonstrate the efficacy of our approach by solving a-UBMP for the D/M/1 queue. We show, using simulation, that the rate solutions obtained are near optimal for minimizing the tail of the AoI distribution. © 2018 IEEE.

  • 21. Charalambous, C. D.
    et al.
    Stavrou, Photios
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Kourtellaris, C. K.
    Tzortzis, I.
    Directed Information Subject to a Fidelity. Applications to Conditionally Gaussian Processes2018In: 2018 European Control Conference, ECC 2018, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 3071-3076, article id 8550054Conference paper (Refereed)
    Abstract [en]

    This paper is concerned with the minimization of directed information over conditional distributions that satisfy a fidelity of reconstructing a conditionally Gaussian random process by another process, causally. This information theoretic extremum problem is directly linked, via bounds to the optimal performance theoretically attainable by non-causal, causal and zero-delay codes of data compression. The application example includes the characterization of causal rate distortion function for conditionally Gaussian random processes subject to a meansquare error fidelity.

  • 22.
    Charalambous, Themistoklis
    et al.
    Aalto Univ, Dept Elect Engn & Automat, Espoo, Finland..
    Kim, Su Min
    Korea Polytech Univ, Dept Elect Engn, Shihung, South Korea..
    Nomikos, Nikolaos
    Univ Aegean, Dept Informat & Commun Syst Engn, Samos, Greece..
    Bengtsson, Mats
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Johansson, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Relay-pair selection in buffer-aided successive opportunistic relaying using a multi-antenna source2019In: Ad hoc networks, ISSN 1570-8705, E-ISSN 1570-8713, Vol. 84, p. 29-41Article in journal (Refereed)
    Abstract [en]

    We study a cooperative network with a buffer-aided multi-antenna source, multiple half-duplex (HD) buffer-aided relays and a single destination. Such a setup could represent a cellular downlink scenario, in which the source can be a more powerful wireless device with a buffer and multiple antennas, while a set of intermediate less powerful devices are used as relays to reach the destination. The main target is to recover the multiplexing loss of the network by having the source and a relay to simultaneously transmit their information to another relay and the destination, respectively. Successive transmissions in such a cooperative network, however, cause inter-relay interference (IRI). First, by assuming global channel state information (CSI), we show that the detrimental effect of IRI can be alleviated by precoding at the source, mitigating or even fully cancelling the interference. A cooperative relaying policy is proposed that employs a joint precoding design and relay-pair selection. Note that both fixed rate and adaptive rate transmissions can be considered. For the case when channel state information is only available at the receiver side (CSIR), we propose a relay selection policy that employs a phase alignment technique to reduce the IRI. The performance of the two proposed relay pair selection policies are evaluated and compared with other state-of-the-art relaying schemes in terms of outage and throughput. The results show that the use of a powerful source can provide considerable performance improvements.

  • 23.
    Chen, Xianhao
    et al.
    Southwest Jiaotong Univ, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China.;Xidian Univ, State Key Lab Integrated Serv Networks, Xian 710126, Shaanxi, Peoples R China..
    Liu, Gang
    Southwest Jiaotong Univ, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Ma, Zheng
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Zhang, Xi
    Texas A&M Univ, Dept Elect & Comp Engn, Networking & Informat Syst Lab, College Stn, TX 77843 USA..
    Xu, Weiqiang
    Zhejiang Sci Tech Univ, Sch Informat Sci & Technol, Hangzhou 310018, Zhejiang, Peoples R China..
    Fan, Pingzhi
    Southwest Jiaotong Univ, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Optimal Power Allocations for Non-Orthogonal Multiple Access Over 5G Full/Half-Duplex Relaying Mobile Wireless Networks2019In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 18, no 1, p. 77-92Article in journal (Refereed)
    Abstract [en]

    This paper investigates the power allocation problems for non-orthogonal multiple access with coordinated direct and relay transmission (CDRT-NOMA), where a base station (BS) communicates with its nearby user directly, while communicating with its far user only through a dedicated relay node (RN). The RN is assumed to operate in either half-duplex relaying (HDR) mode or full-duplex relaying (FDR) mode. Based on instantaneous channel state information (CSI), the dynamic power allocation problems under HDR and FDR schemes are formulated respectively, with the objective of maximizing the minimum user achievable rate. After demonstrating the quasi-concavity of the considered problems, we derive the optimal closed-form power allocation policies under the HDR scheme and the FDR scheme. Then, a hybrid relaying scheme dynamically switching between HDR and FDR schemes is further designed. Moreover, we also study the fixed power allocation problems for the considered CDRT-NOMA systems based on statistical CSI so as to optimize the long-term system performance. The simulations show that our proposed power allocation policies can significantly enhance the performance of CDRT-NOMA systems.

  • 24.
    Ciftci, Baris
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Norrga, Staffan
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Kildehöj, Lars
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    A Proposal for Wireless Control of Submodules in Modular Multilevel Converters2018Conference paper (Refereed)
    Abstract [en]

    The modular multilevel converter is one of the most preferred converters for high-power conversion applications. Wireless control of the submodules can contribute to its evolution by lowering the material and labor costs of cabling and by increasing the availability of the converter. However, wireless control leads to many challenges for the control and modulation of the converter as well as for proper low-latency high-reliability communication. This paper investigates the tolerable asynchronism between phase-shifted carriers used in modulation from a wireless control point of view and proposes a control method along with communication protocol for wireless control. The functionality of the proposed method is validated by computer simulations in steady state.

  • 25.
    del Aguila Pla, Pol
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jaldén, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Cell detection by functional inverse diffusion and non-negative group sparsity – Part I: Modeling and Inverse Problems2018In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 66, no 20, p. 5407-5421Article in journal (Refereed)
    Abstract [en]

    In this two-part paper, we present a novel framework and methodology to analyze data from certain image-based biochemical assays, e.g., ELISPOT and Fluorospot assays. In this first part, we start by presenting a physical partial differential equations (PDE) model up to image acquisition for these biochemical assays. Then, we use the PDEs' Green function to derive a novel parametrization of the acquired images. This parametrization allows us to propose a functional optimization problem to address inverse diffusion. In particular, we propose a non-negative group-sparsity regularized optimization problem with the goal of localizing and characterizing the biological cells involved in the said assays. We continue by proposing a suitable discretization scheme that enables both the generation of synthetic data and implementable algorithms to address inverse diffusion. We end Part I by providing a preliminary comparison between the results of our methodology and an expert human labeler on real data. Part II is devoted to providing an accelerated proximal gradient algorithm to solve the proposed problem and to the empirical validation of our methodology.

  • 26.
    del Aguila Pla, Pol
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jaldén, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Cell detection by functional inverse diffusion and non-negative group sparsity – Part II: Proximal optimization and Performance evaluation2018In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 66, no 20, p. 5422-5437Article in journal (Refereed)
    Abstract [en]

    In this two-part paper, we present a novel framework and methodology to analyze data from certain image-based biochemical assays, e.g., ELISPOT and Fluorospot assays. In this second part, we focus on our algorithmic contributions. We provide an algorithm for functional inverse diffusion that solves the variational problem we posed in Part I. As part of the derivation of this algorithm, we present the proximal operator for the non-negative group-sparsity regularizer, which is a novel result that is of interest in itself, also in comparison to previous results on the proximal operator of a sum of functions. We then present a discretized approximated implementation of our algorithm and evaluate it both in terms of operational cell-detection metrics and in terms of distributional optimal-transport metrics.

  • 27.
    del Aguila Pla, Pol
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jaldén, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Cell detection on image-based immunoassays2018In: 2018 IEEE 15th International Symposium on Biomedical Imaging (ISBI 2018), IEEE, 2018, p. 431-435Conference paper (Refereed)
    Abstract [en]

    Cell detection and counting in the image-based ELISPOT and Fluorospot immunoassays is considered a bottleneck.The task has remained hard to automatize, and biomedical researchers often have to rely on results that are not accurate.Previously proposed solutions are heuristic, and data-based solutions are subject to a lack of objective ground truth data. In this paper, we analyze a partial differential equations model for ELISPOT, Fluorospot, and assays of similar design. This leads us to a mathematical observation model forthe images generated by these assays. We use this model to motivate a methodology for cell detection. Finally, we provide a real-data example that suggests that this cell detection methodology and a human expert perform comparably.

  • 28.
    del Aguila Pla, Pol
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jaldén, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Cell detection on image-based immunoassays2018In: 2018 IEEE 15Th International Symposium On Biomedical Imaging (ISBI 2018), Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 431-435Conference paper (Refereed)
    Abstract [en]

    Cell detection and counting in the image-based ELISPOT and Fluorospot immunoassays is considered a bottleneck. The task has remained hard to automatize, and biomedical researchers often have to rely on results that are not accurate. Previously proposed solutions are heuristic, and data-based solutions are subject to a lack of objective ground truth data. In this paper, we analyze a partial differential equations model for ELISPOT, Fluorospot, and assays of similar design. This leads us to a mathematical observation model for the images generated by these assays. We use this model to motivate a methodology for cell detection. Finally, we provide a real-data example that suggests that this cell detection methodology and a human expert perform comparably.

  • 29.
    del Aguila Pla, Pol
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jaldén, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Convolutional group-sparse coding and source localization2018Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a new interpretation of non-negatively constrained convolutional coding problems as blind deconvolution problems with spatially variant point spread function. In this light, we propose an optimization framework that generalizes our previous work on non-negative group sparsity for convolutional models. We then link these concepts to source localization problems that arise in scientific imaging, and provide a visual example on an image derived from data captured by the Hubble telescope.

  • 30.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Gkatzikis, Lazaros
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    On Maximizing Sensor Network Lifetime by Energy Balancing2018In: IEEE Transactions on Control of Network Systems, ISSN 2325-5870, Vol. 5, no 3Article in journal (Refereed)
    Abstract [en]

    Many physical systems, such as water/electricity distribution networks, are monitored by battery-powered wireless-sensor networks (WSNs). Since battery replacement of sensor nodes is generally difficult, long-term monitoring can be only achieved if the operation of the WSN nodes contributes to long WSN lifetime. Two prominent techniques to long WSN lifetime are 1) optimal sensor activation and 2) efficient data gathering and forwarding based on compressive sensing. These techniques are feasible only if the activated sensor nodes establish a connected communication network (connectivity constraint), and satisfy a compressive sensing decoding constraint (cardinality constraint). These two constraints make the problem of maximizing network lifetime via sensor node activation and compressive sensing NP-hard. To overcome this difficulty, an alternative approach that iteratively solves energy balancing problems is proposed. However, understanding whether maximizing network lifetime and energy balancing problems are aligned objectives is a fundamental open issue. The analysis reveals that the two optimization problems give different solutions, but the difference between the lifetime achieved by the energy balancing approach and the maximum lifetime is small when the initial energy at sensor nodes is significantly larger than the energy consumed for a single transmission. The lifetime achieved by energy balancing is asymptotically optimal, and that the achievable network lifetime is at least 50% of the optimum. Analysis and numerical simulations quantify the efficiency of the proposed energy balancing approach.

  • 31.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Santi, Paolo
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Vasilakos, Athanasios
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    The sensable city: A survey on the deployment and management for smart city monitoringIn: IEEE Communications Surveys and Tutorials, ISSN 1553-877X, E-ISSN 1553-877XArticle in journal (Refereed)
  • 32.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Optimal Node Deployment and Energy Provision for Wirelessly Powered Sensor Networks2018In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 2, p. 407-423Article in journal (Refereed)
    Abstract [en]

    In a typical wirelessly powered sensor network (WPSN), wireless chargers provide energy to sensor nodes by using wireless energy transfer (WET). The chargers can greatly improve the lifetime of a WPSN using energy beamforming by a proper charging scheduling of energy beams. However, the supplied energy still may not meet the demand of the energy of the sensor nodes. This issue can be alleviated by deploying redundant sensor nodes, which not only increase the total harvested energy, but also decrease the energy consumption per node provided that an efficient  scheduling of the sleep/awake of the nodes is performed. Such a problem of joint optimal sensor deployment, WET scheduling, and node activation is posed and investigated in this paper. The problem is an integer optimization that is challenging due to the binary decision variables and non-linear constraints. Based on the analysis of the necessary condition such that the WPSN be immortal, we decouple the original problem into a node deployment problem and a charging and activation scheduling problem. Then, we propose an algorithm and prove that it achieves the optimal solution under a mild condition. The simulation results show that the proposed algorithm reduces the needed nodes to deploy by approximately 16%, compared to a random-based approach. The simulation also shows if the battery buffers are large enough, the optimality condition will be easy to meet.

  • 33.
    Fang, Zequn
    et al.
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Ma, Zheng
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Karagiannidis, George K.
    Aristotle Univ Thessaloniki, Elect & Comp Engn Dept, Thessaloniki, Greece..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Fan, Pingzhi
    Southwest Jiaotong Univ, Prov Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Low complexity decoding of Reed-Solomon codes over magnetic recording channels2019In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 55, no 3, p. 159-160Article in journal (Refereed)
    Abstract [en]

    A low complexity soft-decision decoding technique is presented for Reed-Solomon codes, over magnetic recording channels (MRC), by considering symbol and bit reliability, jointly. A symbol detection scheme for burst error scenarios has been put forward for the iterative error-and-erasure decoding algorithm (IEED), which is based on multiple trials, and is a combination of the generalised minimum distance and Chase-2 decoding schemes. In order to decrease complexity, the decoding test patterns are used in a certain order, while the stopping criteria is also discussed. Simulations show that the proposed algorithms can achieve almost the same performance as that of IEED for the additive white Gaussian noise channel and slightly better performance in MRC, but with significantly less complexity.

  • 34.
    Flierl, Markus
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Girod, Bernd
    Stanford University.
    Generalized B pictures and the draft H.264/AVC video-compression standard2003In: IEEE transactions on circuits and systems for video technology (Print), ISSN 1051-8215, E-ISSN 1558-2205Article in journal (Refereed)
  • 35.
    Flierl, Markus
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Girod, Bernd
    Stanford University.
    Systems, methods, devices and arrangements for motion-compensated image processing and coding2008Patent (Other (popular science, discussion, etc.))
  • 36.
    Flierl, Markus
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Girod, Bernd
    Stanford University.
    Video Coding with Motion-Compensated Lifted Wavelet Transforms2004In: Signal processing. Image communication, ISSN 0923-5965, E-ISSN 1879-2677Article in journal (Refereed)
  • 37.
    Flierl, Markus
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Mavlankar, Aditya
    Stanford University.
    Girod, Bernd
    Stanford University.
    Motion and Disparity Compensated Coding for Multiview Video2007In: IEEE transactions on circuits and systems for video technology (Print), ISSN 1051-8215, E-ISSN 1558-2205Article in journal (Refereed)
  • 38.
    Flierl, Markus
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Vandergheynst, Pierre
    EPFL.
    Distributed Coding of Highly Correlated Image Sequences with Motion-Compensated Temporal Wavelets2006In: EURASIP Journal on Applied Signal ProcessingArticle in journal (Refereed)
  • 39.
    Flierl, Markus
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Wiegand, Thomas
    TU Berlin.
    Girod, Bernd
    Stanford University.
    Rate-constrained multihypothesis prediction for motion-compensated video compression2002In: IEEE transactions on circuits and systems for video technology (Print), ISSN 1051-8215, E-ISSN 1558-2205Article in journal (Refereed)
  • 40.
    Gao, Yulan
    et al.
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiao, Yue
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Wu, Mingming
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Shao, Jinliang
    Univ Elect Sci & Technol China, Sch Math Sci, Chengdu 611731, Sichuan, Peoples R China..
    Game Theory-Based Anti-Jamming Strategies for Frequency Hopping Wireless Communications2018In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 8, p. 5314-5326Article in journal (Refereed)
    Abstract [en]

    In frequency hopping (FH) wireless communications, finding an effective transmission strategy to properly mitigate jamming has been recently considered as a critical issue, due to the inherent broadcast nature of wireless communications. Recently, game theory has been proposed as a powerful tool for dealing with the jamming problem, which can be considered as a player (jammer) playing against a user (transmitter). Different from existing results, in this paper, a bimatrix game framework is developed for modeling the interaction process between the transmitter and the jammer, and the sufficient and necessary conditions for Nash equilibrium (NE) strategy of the game are obtained under the linear constraints. Furthermore, the relationship between the NE solution and the global optimal solution of the corresponding quadratic programming is presented. In addition, a special analysis case is developed based on the continuous game framework in which each player has a continuum of strategies. Finally, we show that the performance can be improved based on our game theoretic framework, which is verified by numerical investigations.

  • 41.
    Ghauch, Hadi
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Mahboob Ur Rahman, Muhammad
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Imtiaz, Sahar
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Qvarfordt, Christer
    Huawei.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    User Assignment in C-RAN Systems: Algorithms and BoundsIn: Article in journal (Refereed)
  • 42.
    Ghauch, Hadi
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Kim, Taejoon
    KTH, School of Electrical Engineering and Computer Science (EECS). City University of Hong Kong.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Low-Overhead Coordination in Sub-28 Millimeter-Wave Networks2018Conference paper (Refereed)
  • 43. Ghayem, Fateme
    et al.
    Sadeghi, Mostafa
    Babaie-Zadeh, Massoud
    Chatterjee, Saikat
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jutten, Christian
    Sparse Signal Recovery Using Iterative Proximal Projection2018In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 66, no 4, p. 879-894Article in journal (Refereed)
    Abstract [en]

    This paper is concerned with designing efficient algorithms for recovering sparse signals from noisy underdetermined measurements. More precisely, we consider minimization of a nonsmooth and nonconvex sparsity promoting function subject to an error constraint. To solve this problem, we use an alternating minimization penalty method, which ends up with an iterative proximal-projection approach. Furthermore, inspired by accelerated gradient schemes for solving convex problems, we equip the obtained algorithm with a so-called extrapolation step to boost its performance. Additionally, we prove its convergence to a critical point. Our extensive simulations on synthetic as well as real data verify that the proposed algorithm considerably outperforms some well-known and recently proposed algorithms.

  • 44.
    Ghourchian, Hamid
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. Sharif Univ Technol, Elect Engn Dept, Tehran 11155, Iran.
    Amini, Arash
    Sharif Univ Technol, Elect Engn Dept, Tehran 11155, Iran.;Sharif Univ Technol, Adv Commun Res Inst, Tehran 11155, Iran..
    Gohari, Amin
    Sharif Univ Technol, Elect Engn Dept, Tehran 11155, Iran.;Sharif Univ Technol, Adv Commun Res Inst, Tehran 11155, Iran..
    How Compressible Are Innovation Processes?2018In: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 64, no 7, p. 4843-4871Article in journal (Refereed)
    Abstract [en]

    The sparsity and compressibility of finitedimensional signals are of great interest in fields, such as compressed sensing. The notion of compressibility is also extended to infinite sequences of independent identically distributed or ergodic random variables based on the observed error in their nonlinear k-term approximation. In this paper, we use the entropy measure to study the compressibility of continuous-domain innovation processes (alternatively known as white noise). Specifically, we define such a measure as the entropy limit of the doubly quantized (time and amplitude) process. This provides a tool to compare the compressibility of various innovation processes. It also allows us to identify an analogue of the concept of "entropy dimension" which was originally defined by Renyi for random variables. Particular attention is given to stable and impulsive Poisson innovation processes. Here, our results recognize Poisson innovations as the more compressible ones with an entropy measure far below that of stable innovations. While this result departs from the previous knowledge regarding the compressibility of impulsive Poisson laws compared with continuous fat-tailed distributions, our entropy measure ranks alpha-stable innovations according to their tail.

  • 45.
    Ghourchian, Hamid
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. Sharif Univ Technol, Dept Elect Engn, Tehran 11155, Iran..
    Aminian, Gholamali
    Sharif Univ Technol, Dept Elect Engn, Tehran 11155, Iran.;Sharif Univ Technol, Adv Commun Res Inst, Tehran 11155, Iran..
    Gohari, Amin
    Sharif Univ Technol, Dept Elect Engn, Tehran 11155, Iran.;Sharif Univ Technol, Adv Commun Res Inst, Tehran 11155, Iran..
    Mirmohseni, Mahtab
    Sharif Univ Technol, Dept Elect Engn, Tehran 11155, Iran.;Sharif Univ Technol, Adv Commun Res Inst, Tehran 11155, Iran..
    Nasiri-Kenari, Masoumeh
    Sharif Univ Technol, Dept Elect Engn, Tehran 11155, Iran.;Sharif Univ Technol, Adv Commun Res Inst, Tehran 11155, Iran..
    On the Capacity of a Class of Signal-Dependent Noise Channels2018In: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 64, no 12, p. 7828-7846Article in journal (Refereed)
    Abstract [en]

    In some applications, the variance of additive measurement noise depends on the signal that we aim to measure. For instance, additive signal-dependent Gaussian noise (ASDGN) channel models are used in molecular and optical communication. Herein, we provide lower and upper bounds on the capacity of additive signal-dependent noise (ASDN) channels. The first lower bound is based on an extension of majorization inequalities, and the second lower bound utilizes the properties of the differential entropy. The lower bounds are valid for arbitrary ASDN channels. The upper bound is based on a previous idea of the authors ("symmetric relative entropy") and is applied to the ASDGN channels. These bounds indicate that in the ASDN channels (unlike the classical additive white Gaussian noise channels), the capacity does not necessarily become larger by reducing the noise variance function. We also provide sufficient conditions under which the capacity becomes infinite. This is complemented by some conditions implying that the capacity is finite, and a unique capacity achieving measure exists (in the sense of the output measure).

  • 46.
    Girdzijauskas, Ivana
    et al.
    Ericsson.
    Flierl, Markus
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Georgakis, Apostolos
    Ericsson.
    Kumar Rana, Pravin
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Methods and arrangements for 3D scene representation2010Patent (Other (popular science, discussion, etc.))
  • 47.
    Girdzijauskas, Ivana
    et al.
    Ericsson.
    Flierl, Markus
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Kumar Rana, Pravin
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Method and processor for 3D scene representation2012Patent (Other (popular science, discussion, etc.))
  • 48.
    Girod, Bernd
    et al.
    Stanford University.
    Flierl, Markus
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Videocodierung mit mehreren Referenzbildern2003In: it - Information Technology, ISSN 1611-2776Article in journal (Refereed)
  • 49.
    Hamadeh, Anas
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Anomaly Detection in A Multivariate DataStream in a Highly Scalable and Fault Tolerant Architecture2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The process of monitoring telecommunication systems performance by investigatingKey Performance Indicators (KPI) and Performance Measurements(PMs) is crucial for valuable sustainable solutions and requires analysts' interventionwith profound knowledge to help mitigate vulnerabilities and risks.This work focuses on PMs anomaly detection in order to automate the processof discovering unacceptable Radio Access Network (RAN) performance byleveraging K-meansjj algorithm and producing an anomaly scoring mechanism.It also oers a streaming, fault tolerant, scalable and loosely coupled architectureto process data on the y based on a normal behavior model. Theproposed architecture is used to test the anomaly scoring system where variousdata patterns are ingested. The tests focused on inspecting the anomaly score'sconsistency, variability and sensitivity. The results were highly impacted by thereal-time standardization process of data, and the scores were not entirely sensitiveto changes in constant features; however, the experiment yielded acceptableresults when the correlation between features was taken into account.

  • 50.
    Henrik, Forssell
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Al-Zubaidy, Hussein
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Physical Layer Authentication in Mission-Critical MTC Networks: A Security and Delay Performance Analysis2019In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 4, p. 795-808Article in journal (Refereed)
    Abstract [en]

    We study the detection and delay performance impacts of a feature-based physical layer authentication (PLA) protocol in mission-critical machine-type communication (MTC) networks. The PLA protocol uses generalized likelihood-ratio testing based on the line-of-sight (LOS), single-input multiple- output channel-state information in order to mitigate imper- sonation attempts from an adversary node. We study the de- tection performance, develop a queueing model that captures the delay impacts of erroneous decisions in the PLA (i.e., the false alarms and missed detections), and model three different adversary strategies: data injection, disassociation, and Sybil attacks. Our main contribution is the derivation of analytical delay performance bounds that allow us to quantify the delay introduced by PLA that potentially can degrade the performance in mission-critical MTC networks. For the delay analysis, we utilize tools from stochastic network calculus. Our results show that with a sufficient number of receive antennas (approx. 4-8) and sufficiently strong LOS components from legitimate devices, PLA is a viable option for securing mission-critical MTC systems, despite the low latency requirements associated to corresponding use cases. Furthermore, we find that PLA can be very effective in detecting the considered attacks, and in particular, it can significantly reduce the delay impacts of disassociation and Sybil attacks.

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