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  • 1.
    Zhang, Zhengquan
    et al.
    Southwest Jiaotong Univ, Chengdu, Sichuan, Peoples R China..
    Xiao, Yue
    Southwest Jiaotong Univ, Chengdu, Sichuan, Peoples R China..
    Ma, Zheng
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu, Sichuan, Peoples R China..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Ding, Zhiguo
    Univ Manchester, Commun, Manchester, Lancs, England..
    Lei, Xianfu
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu, Sichuan, Peoples R China..
    Karagiannidis, George K.
    Aristotle Univ Thessaloniki, Elect & Comp Engn Dept, Thessaloniki, Greece.;Aristotle Univ Thessaloniki, Digital Telecommun Syst & Networks Lab, Thessaloniki, Greece..
    Fan, Pingzhi
    Southwest Jiaotong Univ, Chengdu, Sichuan, Peoples R China..
    6G WIRELESS NETWORKS Vision, Requirements, Architecture, and Key Technologies2019In: IEEE Vehicular Technology Magazine, ISSN 1556-6072, E-ISSN 1556-6080, Vol. 14, no 3, p. 28-41Article in journal (Refereed)
    Abstract [en]

    A key enabler for the intelligent information society of 2030, 6G networks are expected to provide performance superior to 5G and satisfy emerging services and applications. In this article, we present our vision of what 6G will be and describe usage scenarios and requirements for multi-terabyte per second (Tb/s) and intelligent 6G networks. We present a large-dimensional and autonomous network architecture that integrates space, air, ground, and underwater networks to provide ubiquitous and unlimited wireless connectivity. We also discuss artificial intelligence (AI) and machine learning [1], [2] for autonomous networks and innovative air-interface design. Finally, we identify several promising technologies for the 6G ecosystem, including terahertz (THz) communications, very-large-scale antenna arrays [i.e., supermassive (SM) multiple-input, multiple-output (MIMO)], large intelligent surfaces (LISs) and holographic beamforming (HBF), orbital angular momentum (OAM) multiplexing, laser and visible-light communications (VLC), blockchain-based spectrum sharing, quantum communications and computing, molecular communications, and the Internet of Nano-Things.

  • 2.
    Olofsson, Per E.
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Brandt, Ludwig
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Magnusson, Klas E. G.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Frisk, Thomas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Jaldén, Joakim
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Önfelt, Björn
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    A collagen-based microwell migration assay to study NK-target cell interactions2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 10672Article in journal (Refereed)
    Abstract [en]

    Natural killer (NK) cell cytotoxicity in tissue is dependent on the ability of NK cells to migrate through the extracellular matrix (ECM) microenvironment. Traditional imaging studies of NK cell migration and cytotoxicity have utilized 2D surfaces, which do not properly reproduce the structural and mechanical cues that shape the migratory response of NK cells in vivo. Here, we have combined a microwell assay that allows long-term imaging and tracking of small, well-defined populations of NK cells with an interstitial ECM-like matrix. The assay allows for long-term imaging of NK-target cell interactions within a confined 3D volume. We found marked differences in motility between individual cells with a small fraction of the cells moving slowly and being confined to a small volume within the matrix, while other cells moved more freely. A majority of NK cells also exhibited transient variation in their motility, alternating between periods of migration arrest and movement. The assay could be used as a complement to in vivo imaging to study human NK cell heterogeneity in migration and cytotoxicity.

  • 3.
    Maros, Marie
    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.
    A geometrically converging dual method for distributed optimization over time-varying graphs2019In: IEEE Transactions on Automatic ControlArticle in journal (Refereed)
  • 4.
    Huang, Shaocheng
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Achievable Rate Analysis of Millimeter Wave Channels with Random Coding Error Exponent2019In: IEEE International Conference on Communications, Institute of Electrical and Electronics Engineers (IEEE), 2019, Vol. 2019, article id 8761470Conference paper (Refereed)
    Abstract [en]

    Millimeter Wave (mmWave) communication has attracted massive attentions, since the abundant available bandwidth can potentially provide reliable communication with orders of magnitude capacity improvements relative to microwave. However, the achievable rate of mmWave channels under latency and reliability constraints is still not quite clear. We investigate the achievable rates of mmWave channels by random coding error exponent (RCEE) with finite blocklength. With imperfect channel state information at the receiver, the exact and approximate analytical expressions of the training based maximum achievable rate are derived to capture the relationship among rate-latency-reliability. Additionally, the relationship between the training based maximum achievable rate and bandwidth is investigated. We show that there exists critical bandwidth to maximize the training based maximum achievable rate for the non-line-of-sight (NLoS) propagation. Numerical results show that the approximate expression of the training based maximum achievable rate are tight and can capture the tendency at low SNRs. In addition, results show that for a given rate, one can reduce both packet duration and decoding error probability by increasing bandwidth. Results also suggest that in some mmWave bands, e.g. 57-64 GHz band, the performance, i.e., Gallager function, is significantly affected by frequency selective power absorption.

  • 5.
    Yang, Ping
    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..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Guan, Yong Liang
    Nanyang Technol Univ, Sch Elect & Elect Engn, Singapore 639798, Singapore..
    Li, Shaoqian
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiang, Wei
    James Cook Univ, Coll Sci & Engn, Cairns, Qld 4878, Australia..
    Adaptive Spatial Modulation MIMO Based on Machine Learning2019In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 9, p. 2117-2131Article in journal (Refereed)
    Abstract [en]

    In this paper, we propose a novel framework of low-cost link adaptation for spatial modulation multiple-input multiple-output (SM-MIMO) systems-based upon the machine learning paradigm. Specifically, we first convert the problems of transmit antenna selection (TAS) and power allocation (PA) in SM-MIMO to ones-based upon data-driven prediction rather than conventional optimization-driven decisions. Then, supervised-learning classifiers (SLC), such as the K-nearest neighbors (KNN) and support vector machine (SVM) algorithms, are developed to obtain their statistically-consistent solutions. Moreover, for further comparison we integrate deep neural networks (DNN) with these adaptive SM-MIMO schemes, and propose a novel DNN-based multi-label classifier for TAS and PA parameter evaluation. Furthermore, we investigate the design of feature vectors for the SLC and DNN approaches and propose a novel feature vector generator to match the specific transmission mode of SM. As a further advance, our proposed approaches are extended to other adaptive index modulation (IM) schemes, e.g., adaptive modulation (AM) aided orthogonal frequency division multiplexing with IM (OFDM-IM). Our simulation results show that the SLC and DNN-based adaptive SM-MIMO systems outperform many conventional optimization-driven designs and are capable of achieving a near-optimal performance with a significantly lower complexity.

  • 6.
    Asif, Rizwan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, Centre for Autonomous Systems, CAS.
    Löffel, Hendrik Jan
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, Centre for Autonomous Systems, CAS.
    Assavasangthong, Vorapol
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, Centre for Autonomous Systems, CAS.
    Martinelli, Giulio
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, Centre for Autonomous Systems, CAS.
    Gajland, Phillip
    KTH, School of Electrical Engineering and Computer Science (EECS), Theoretical Computer Science, TCS.
    Rodríguez Gálvez, Borja
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Aerial path planning for multi-vehicles2019In: Proceedings - IEEE 2nd International Conference on Artificial Intelligence and Knowledge Engineering, AIKE 2019, Institute of Electrical and Electronics Engineers (IEEE), 2019, p. 267-272, article id 8791733Conference paper (Refereed)
    Abstract [en]

    Unmanned Aerial Vehicles (UAV) are a potential solution to fast and cost efficient package delivery services. There are two types of UAVs, namely fixed wing (UAV-FW) and rotor wing (UAV-RW), which have their own advantages and drawbacks. In this paper we aim at providing different solutions to a collaborating multi-agent scenario combining both UAVs types. We show the problem can be reduced to the facility location problem (FLP) and propose two local search algorithms to solve it: Tabu search and simulated annealing.

  • 7.
    Yu, Hanxiao
    et al.
    Beijing Inst Technol, Sch Informat & Elect, Beijing 100081, Peoples R China..
    Fei, Zesong
    Beijing Inst Technol, Sch Informat & Elect, Beijing 100081, Peoples R China..
    Cao, Congzhe
    Univ Alberta, Dept Elect & Comp Engn, Edmonton, AB T6G 1H9, Canada..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jia, Dai
    Beijing Inst Technol, Sch Informat & Elect, Beijing 100081, Peoples R China..
    Ye, Neng
    Beijing Inst Technol, Sch Informat & Elect, Beijing 100081, Peoples R China..
    Analysis of irregular repetition spatially-coupled slotted ALOHA2019In: Science China Information Sciences, ISSN 1674-733X, E-ISSN 1869-1919, Vol. 62, no 8, article id 080302Article in journal (Refereed)
    Abstract [en]

    Contention-based access is a promising technology for massive and sporadic transmissions. In this paper, we propose a novel contention-based multiple access scheme, named irregular repetition spatiallycoupled slotted ALOHA (IRSC-SA), motivated by the spatial coupling and irregular repetition techniques. There are different classes of users and slots in IRSC-SA, which result in unequal protection for different users. Considering that, we derive a novel density evolution (DE) method, which deals with unequal packet protection and introduces Bayesian reasoning to analyze the throughput threshold of the proposed IRSC-SA. Theoretical analysis and simulation results show that the proposed scheme achieves better asymptotic threshold and system packet throughput performance than the conventional spatially-coupled slotted ALOHA.

  • 8.
    Xue, Qing
    et al.
    Southwest Jiaotong Univ, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China.;Chongqing Univ Posts & Telecommun, Sch Commun & Informat Engn, Chongqing 400065, Peoples R China..
    Fang, Xuming
    Southwest Jiaotong Univ, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Mumtaz, Shahid
    Inst Telecomunicacoes, P-3810193 Aveiro, Portugal..
    Rodriguez, Jonathan
    Univ South Wales, Mobile Commun, Pontypridd CF37 1DL, M Glam, Wales..
    Beam Management for Millimeter-Wave Beamspace MU-MIMO Systems2019In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 67, no 1, p. 205-217Article in journal (Refereed)
    Abstract [en]

    Millimeter-wave (mm-wave) communication has attracted increasing attention as a promising technology for 5G networks. One of the key architectural features of mm-wave is the possibility of using large antenna arrays at both the transmitter and receiver sides. Therefore, by employing directional beamforming, both mm-wave base stations (MBSs) and mm-wave user equipments (MUEs) are capable of supporting multi-beam simultaneous transmissions. However, most of the existing research results have only considered a single beam. Thus, the potentials of mm-wave have not been fully exploited yet. In this context, in order to improve the performance of short-range indoor mm-wave networks with multiple reflections, we investigate the challenges and potential solutions of downlink multi-user multi-beam transmission, which can be described as a beamspace multi-user multiple-input multiple-output (MU-MIMO) technique. We first exploit the characteristic of MBS/MUEs supporting multiple beams simultaneously to improve the efficiency of multi-user BF training. Then, we analyze the inter-user interference to avoid beam selection conflicts. Furthermore, we propose blockage control strategies and multi-user multi-beam power allocation solutions for the beamspace MU-MIMO. The theoretical and numerical results demonstrate that the beamspace MU-MIMO compared with single beam transmission can largely improve the rate performance and robustness of mm-wave networks.

  • 9.
    Petreska, Neda
    et al.
    Fraunhofer Inst Embedded Syst & Commun Technol ES, Munich, Germany..
    Al-Zubaidy, Hussein
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Knorr, Rudi
    Fraunhofer Inst Embedded Syst & Commun Technol ES, Munich, Germany..
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Bound-based power optimization for multi-hop heterogeneous wireless industrial networks under statistical delay constraints2019In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 148, p. 262-279Article in journal (Refereed)
    Abstract [en]

    The noticeably increased deployment of wireless networks for battery-limited industrial applications in recent years highlights the need for tractable performance analysis methodologies as well as efficient QoS-aware transmit power management schemes. In this work, we seek to combine several important aspects of such networks, i.e., multi-hop connectivity, channel heterogeneity and the queuing effect, in order to address these needs. We design delay-bound-based algorithms for transmit power minimization and network lifetime maximization of multi-hop heterogeneous wireless networks using our previously developed stochastic network calculus approach for performance analysis of a cascade of buffered wireless fading channels. Our analysis shows an overall transmit power saving of up to 95% compared to a fixed power allocation scheme in case when the service is modeled via a Shannon capacity. For a more realistic set-up, we evaluate the performance of the suggested algorithm in a WirelessHART network, which is a widely used communication standard for industrial process automation applications. We find that link heterogeneity can significantly reduce network lifetime when no efficient power management is applied. Using extensive simulation study we further show that the proposed bound-based power allocation performs reasonably well compared to the real optimum, especially in the case of WirelessHART networks.

  • 10.
    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.

  • 11.
    Pan, Fei
    et al.
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Pang, Zhibo
    ABB Corp Res, S-72226 Vasteras, Sweden..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Wen, Hong
    Univ Elect Sci & Technol China, Dept Aeronaut & Astronaut, Chengdu 611731, Sichuan, Peoples R China..
    Liao, Run-Fa
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Clone Detection Based on Physical Layer Reputation for Proximity Service2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 3948-3957Article in journal (Refereed)
    Abstract [en]

    Proximity-based service (ProSe) provides direct communications among smart sensor nodes in proximity which aims at reserving resource consumption and alleviating the load in base stations, which is a promising solution for smart sensor systems that possess limited computing and energy resources. During the ProSe direct communications, most of the prior art security methods are usually provided by the ProSe function and are based on complex cryptography. However, despite the computing complexity, it is difficult for cryptographic methods to detect clone attack which is a common kind of attack in sensor systems. Clone nodes feature different physical positions but claim colliding IDs with captured nodes. Thus, clone nodes can be detected by spatial differences, in particular, by the surveillance of physical layer channel state information (CSI). However, CSI is not absolute static due to the random noise in wireless propagation environment. Accordingly, the detection accuracy varies with the stability of CSI. To address this challenge, we take the first attempt to introduce physical layer reputation and then elaborate the physical layer reputation based clone detection protocol to detect clone attack in multiple scenarios. The proposed protocol significantly improves the detection rate and false alarm rate and it is validated both by simulations and realizations.

  • 12.
    Ghauch, Hadi
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering.
    Kim, Taejoon
    Univ Kansas, Dept EECS, Lawrence, KS 66045 USA..
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Compressive Sensing with Applications to Millimeter-wave Architectures2019In: 2019 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH AND SIGNAL PROCESSING (ICASSP), IEEE , 2019, p. 7834-7838Conference paper (Refereed)
    Abstract [en]

    To make the system available at low-cost, millimeter-ave (mmWave) multiple-input multiple-output (MIMO) architectures employ analog arrays, which are driven by a limited number of radio frequency (RF) chains. One primary challenge of using large hybrid analog-digital arrays is that the digital baseband cannot directly access the signal to/from each antenna. To address this limitation, recent research has focused on retransmissions, iterative precoding, and subspace decomposition methods. Unlike these approaches that exploited the channel's low-rank, in this work we exploit the sparsity of the received signal at both the transmit/receive antennas. While the signal itself is de facto dense, it is well-known that most signals are sparse under an appropriate choice of basis. By delving into the structured compressive sensing (CS) framework and adapting them to variants of the mmWave hybrid architectures, we provide methodologies to recover the analog signal at each antenna from the (low-dimensional) digital signal. Moreover, we characterizes the minimal numbers of measurement and RF chains to provide this recovery, with high probability. We discuss their applications to common variants of the hybrid architecture. By leveraging the inherent sparsity of the received signal, our analysis reveals that a hybrid MIMO system can be " turned into" a fully digital one: the number of needed RF chains increases logarithmically with the number of antennas.

  • 13.
    Saxena, Vidit
    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.
    Gonzalez, J. E.
    Bengtsson, Mats
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Tullberg, H.
    Stoica, I.
    Contextual multi-armed bandits for link adaptation in cellular networks2019In: NetAI 2019 - Proceedings of the 2019 ACM SIGCOMM Workshop on Network Meets AI and ML, Part of SIGCOMM 2019, Association for Computing Machinery (ACM), 2019, p. 44-49Conference paper (Refereed)
    Abstract [en]

    Cellular networks dynamically adjust the transmission parameters for a wireless link in response to its time-varying channel state. This is known as link adaptation, where the typical goal is to maximize the link throughput. State-of-the-art outer loop link adaptation (OLLA) selects the optimal transmission parameters based on an approximate, offline, model of the wireless link. Further, OLLA refines the offline model by dynamically compensating any deviations from the observed link performance. However, in practice, OLLA suffers from slow convergence and a sub-optimal link throughput. In this paper, we propose a link adaptation approach that overcomes the shortcomings of OLLA through a novel learning scheme. Our approach relies on contextual multi-armed bandits (MAB), where the context vector is composed of the instantaneous wireless channel state along with side information about the link. For a given context, our approach learns the success probability for each of the available transmission parameters, which is then exploited to select the throughput-maximizing parameters. Through numerical experiments, we show that our approach converges faster than OLLA and achieves a higher steady-state link throughput. For frequent and infrequent channel reports respectively, our scheme outperforms OLLA by 15% and 25% in terms of the steady-state link throughpu.

  • 14.
    Schiessl, Sebastian
    et al.
    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.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Caire, Giuseppe
    Delay Performance of the Multiuser MISO Downlink Under Imperfect CSI and Finite-Length Coding2019In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 4, p. 765-779Article in journal (Refereed)
    Abstract [en]

    We use stochastic network calculus to investigate the delay performance of a multiuser MISO system with zero-forcing beamforming. First, we consider ideal assumptions with long codewords and perfect CSI at the transmitter, where we observe a strong channel hardening effect that results in very high reliability with respect to the maximum delay of the application. We then study the system under more realistic assumptions with imperfect CSI and finite blocklength channel coding. These effects lead to interference and to transmission errors, and we derive closed-form approximations for the resulting error probability. Compared to the ideal case, imperfect CSI and finite length coding cause massive degradations in the average transmission rate. Surprisingly, the system nevertheless maintains the same qualitative behavior as in the ideal case: as long as the average transmission rate is higher than the arrival rate, the system can still achieve very high reliability with respect to the maximum delay.

  • 15.
    Händel, Peter
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Wahlström, J.
    Digital contraceptives based on basal body temperature measurements2019In: Biomedical Signal Processing and Control, ISSN 1746-8094, E-ISSN 1746-8108, Vol. 52, p. 141-151Article in journal (Refereed)
    Abstract [en]

    Digital contraceptives and fertility awareness products are currently offered as convenient smartphone applications. The first legitimate contraceptive smartphone app was recently introduced on the European market, with the digital processing based on measurements of the female user's basal body temperature (BBT). According to recent pilot market data, at some Swedish hospitals, up to 5–10% of women seeking abortion had become involuntarily pregnant while using the product. This fact motivates a review of the research on fertility determination based on BBT measurements. This paper provides the first estimation theoretical review and evaluation of BBT-based ovulation detection. From an engineering perspective, it is concluded that the available detection algorithms have similar performance and that the performance is rather insensitive to a one- or two-decimal resolution of the employed thermometer. Further, we highlight that when using the output from proposed ovulation detection algorithms, one must consider not only the uncertainty in the relative time difference of the detected temperature shift and the ovulation, but also the statistical uncertainty of the detection methods due to noisy measurements.

  • 16.
    Liu, Dong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Wang, Chao
    Tongji Univ, Dept Informat & Commun Engn, Shanghai 201804, Peoples R China.;Univ Exeter, Dept Comp Sci, Exeter EX4 4QF, Devon, England..
    Rasmussen, Lars Kildehöj
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Discontinuous Reception for Multiple-Beam Communication2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 46931-46946Article in journal (Refereed)
    Abstract [en]

    Discontinuous reception (DRX) techniques have successfully been proposed for energy savings in 4G radio access systems, which are deployed on legacy 2GHz spectrum bands with signal features of omnidirectional propagation. In upcoming 5G systems, higher frequency spectrum bands will also be utilized. Unfortunately higher frequency bands encounter more significant path loss, thus requiring directional beamforming to aggregate the radiant signal in a certain direction. We, therefore, propose a DRX scheme for multiple beam (DRXB) communication scenarios. The proposed DRXB scheme is designed to avoid unnecessary energy-and-time-consuming beam-training procedures, which enables longer sleep periods and shorter wake-up latency. We provide an analytical model to investigate the receiver-side energy efficiency and transmission latency of the proposed scheme. Through simulations, our approach is shown to have clear performance improvements over the conventional DRX scheme where beam training is conducted in each DRX cycle.

  • 17.
    Yue, Jing
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Pang, Z.
    Distributed BATS-Based Schemes for Uplink of Industrial Internet of Things2019In: ICC 2019 - 2019 IEEE International Conference on Communications (ICC), Institute of Electrical and Electronics Engineers (IEEE), 2019, Vol. 2019Conference paper (Refereed)
    Abstract [en]

    In Industrial Internet of Things (IIoTs), data generated during manufacturing are collected by sensors and need be processed timely. The direction of data transmissions from sensors to processing centers (fog nodes) is often called uplink transmission. In this paper, the cases with single and multiple distributed fog nodes, which are also referred to as centralized and distributed models, are studied. Two distributed schemes based on batched sparse (BATS) codes are proposed separately for the uplink of these two models. The expected rank and the recovery probability of the information from sensors at fog node(s) are derived. Comparison results show that by using the proposed BATS-based schemes, improved transmission reliability can be achieved compared to the XOR-based network coding (NC) scheme.

  • 18.
    Tolli, Antti
    et al.
    Univ Oulu, Ctr Wireless Commun, Oulu, Finland..
    Ghauch, Hadi
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Kaleva, Jarkko
    Univ Oulu, Ctr Wireless Commun, Oulu, Finland..
    Komulainen, Petri
    Mediatek Wireless, Oulu, Finland..
    Bengtsson, Mats
    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.
    Honig, Michael
    Northwestern Univ, EECS Dept, Evanston, IL 60208 USA..
    Lahetkangas, Eeva
    Nokia Bell Labs, Murray Hill, NJ USA..
    Tiirola, Esa
    Nokia Bell Labs, Murray Hill, NJ USA..
    Pajukoski, Kari
    Nokia Bell Labs, Murray Hill, NJ USA..
    Distributed Coordinated Transmission with Forward-Backward Training for 5G Radio Access2019In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 57, no 1, p. 58-64Article in journal (Refereed)
    Abstract [en]

    CoMP transmission and reception have been considered in cellular networks for enabling larger coverage, improved rates, and interference mitigation. To harness the gains of coordinated beamforming, fast information exchange over a backhaul connecting the cooperating BSs is required. In practice, the bandwidth and delay limitations of the backhaul may not be able to meet such stringent demands. These impairments motivate the study of cooperative approaches based only on local CSI that require minimal or no information exchange between the BSs. To this end, several distributed approaches are introduced for CB-CoMP. The proposed methods rely on the channel reciprocity and iterative spatially precoded over-the-air pilot signaling. We elaborate how F-B training facilitates distributed CB by allowing BSs and UEs to iteratively optimize their respective transmitters/receivers based on only locally measured CSI. The trade-off due to the overhead from the F-B iterations is discussed. We also consider the challenge of dynamic TDD where the UE-UE channel knowledge cannot be acquired at the BSs by exploiting channel reciprocity. Finally, standardization activities and practical requirements for enabling the proposed F-B training schemes in 5G radio access are discussed.

  • 19.
    Panigrahi, Smruti Ranjan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligenta system, Information Science and Engineering.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics..
    Bengtsson, Mats
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligenta system, Information Science and Engineering.
    Distributed Detection with Non-identical Wireless Sensors for Industrial Applications2019In: 2019 IEEE International Conference on Industrial Technology (ICIT), IEEE, 2019, p. 1403-1408Conference paper (Refereed)
    Abstract [en]

    There has been very little exploration when it comes to design distributed detection techniques and data fusion rules with non-identical sensors. This concept can be utilized in many possible applications within industrial automation, surveillance and safety. Here, for a global event, some of the sensors/detectors in the network can observe the full set of the hypotheses, whereas the remaining sensors infer more than one hypotheses as a single hypothesis. The local decisions are sent to the decision fusion center (DFC) over a multiple access wireless channel. In this paper, a fusion rule based on minimization of variance of the local mis-detection is proposed. The presence of sensors with limited detection capabilities is found to have a positive impact on the overall system performance, both in terms of probability of detection and transmit power consumption. Additionally, when the DFC is equipped with a large antenna array,the overall transmit power consumption can be reduced without sacrificing the detection performance.

  • 20.
    Maros, Marie
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Distributed Optimization in Time-Varying Environments2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Solving optimization problems in a distributed manner is critical in many systems. Many relevant systems are distributed in nature in the sense that they consist of autonomous agents that are to come to a joint decision based on a certain metric. In many cases, these agents may collect information independently and would therefore have to centralize all the data. In applications were this is not a viable approach distributed solutions are desirable.

    In this thesis, we study distributed optimization methods in time-varying environments. In the first part of the thesis, we consider optimization problems that evolve over time in a controlled manner. We propose the use of the Alternating Direction Method of Multipliers (ADMM) due to its flexibility in step-size selection. We establish ADMM's ability to follow an optimal point as it moves over time. In our set-up, a distributed variant of ADMM is allowed to perform a single iteration per problem change. Under smoothness assumptions on the objective and constraint functions we establishthat there exists a sufficiently small variation of the problem data for which we can guarantee that ADMM will be able to follow the optimal point in a decentralized manner. These conditions are less stringent than the conditions found in the literature. Later on, we introduce a stochastic model for the variation of the problem's data. Under some assumptions, we establish that decentralized ADMM is capable of remaining in a bounded mean square neighbourhood of a primal-dual optimal point. Introducing a stochastic model allows to us relax many of the requirements found in the literature, while still providing some guarantees. We provide with application examples and simulations for both scenarios.

    In the second part of the thesis we consider distributed optimization methods that converge over time-varying networks. We propose the first dual method to converge linearly on time-varying networks, in which we allow the networks to become disconnected. We establish that the method converges R-linearly and illustrate that under some circumstances it performs better than other state of the art methods, while, at the same time, cutting the required information exchanges in half. Since the proposed method is computationally quite expensive we propose a linearized and therefore computationally cheaper version of our method. Finally, we establish that the linearized version will also converge R-linearly on time-varying graphs and quantify the loss in convergence rate due to the approximation.

  • 21. Maros, Marie
    et al.
    Jaldén, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Eco-panda: A Computationally Economic, Geometrically Converging Dual Optimization Method on Time-varying Undirected GRaphs2019Conference paper (Refereed)
  • 22.
    Maros, Marie
    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.
    ECO-PANDA: A COMPUTATIONALLY ECONOMIC, GEOMETRICALLY CONVERGING DUAL OPTIMIZATION METHOD ON TIME-VARYING UNDIRECTED GRAPHS2019In: 2019 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH AND SIGNAL PROCESSING (ICASSP), IEEE , 2019, p. 5257-5261Conference paper (Refereed)
    Abstract [en]

    In this paper we consider distributed convex optimization over time-varying undirected graphs. We propose a linearized version of primarily averaged network dual ascent (PANDA) that keeps the advantages of PANDA while requiring less computational costs. The proposed method, economic primarily averaged network dual ascent (Eco-PANDA), provably converges at R-linear rate to the optimal point given that the agents' objective functions are strongly convex and have Lipschitz continuous gradients. Therefore, the method is competitive, in terms of type of rate, with both DIGing and PANDA. The proposed method halves the communication costs of methods like DIGing while still converging R-linearly and having the same per iterate complexity.

  • 23.
    Olguín Muñoz, Manuel Osvaldo
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Wang, Junjue
    Carnegie Mellon University.
    Satyanarayanan, Mahadev
    Carnegie Mellon University.
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    EdgeDroid: An Experimental Approach to Benchmarking Human-in-the-Loop Applications2019In: Proceedings of the 20th International Workshop on Mobile Computing Systems and Applications (HotMobile '19), Association for Computing Machinery (ACM), 2019Conference paper (Refereed)
    Abstract [en]

    Many emerging mobile applications, including augmented reality (AR) and wearable cognitive assistance (WCA), aim to provide seamless user interaction. However, the complexity of benchmarking these human-in-the-loop applications limits reproducibility and makes performance evaluation difficult. In this paper, we present EdgeDroid, a benchmarking suite designed to reproducibly evaluate these applications.Our core idea rests on recording traces of user interaction, which are then replayed at benchmarking time in a controlled fashion based on an underlying model of human behavior. This allows for an automated system that greatly simplifies benchmarking large scale scenarios and stress testing the application.Our results show the benefits of EdgeDroid as a tool for both system designers and application developers.

  • 24.
    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.;Southeast Univ, Natl Mobile Commun Res Lab, Nanjing 210096, Jiangsu, 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.
    Energy Efficient Power Allocation With Demand Side Coordination for OFDMA Downlink Transmissions2019In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 18, no 4, p. 2141-2155Article in journal (Refereed)
    Abstract [en]

    We investigate the energy-efficient power allocation for downlink transmission in orthogonal frequency division multiple access-based long term evolution systems. Aiming at realizing on-demand power allocation in cellular networks, we explore the available coordination between the base station and multiple users, and propose a new performance merit, namely, the demand side coordination energy efficiency (DSC-EE), which captures the system normalized EE and the demand side information. The proposed DSC-EE is designed to exploit individual disparities from both the entire system and the individual own expected utility perspectives. Our goal is to maximize the DSC-EE of the system via power allocation with a constraint on the maximum transmit power. Specifically, the objective function of DSC-EE maximization problem in a fractional form can be transformed into a subtractive form that is more tractable based on the fractional programming theory. The convergence property of the proposed algorithms and the meaningfulness of the proposed performance merit related to the EE are demonstrated by simulations. The comparison of four EE metrics, the EE and the rate fairness, global-EE, Sum-EE, and DSC-EE, shows that the DSC-EE maximization tends to achieve high implementation level of on-demand power allocation while ensuring the EE of the system. In addition, when the minimum rate replaces the expected rate in the DSC-EE, further performance comparison indicates the necessity and impact of the expected rate in the tolerable quality of service bias function.

  • 25.
    Qi, Nan
    et al.
    Nanjing Univ Aeronaut & Astronaut, Minist Ind & Informat Technol, Key Lab Dynam Cognit Syst Electromagnet Spectrum, Nanjing 210016, Peoples R China.;Southeast Univ, Natl Mobile Commun Res Lab, Nanjing 210096, 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..
    Yao, Rugui
    Northwestern Polytech Univ, Sch Elect & Informat, Xian 710072, Shaanxi, Peoples R China..
    Mumtaz, Shahid
    Inst Telecomunicacoes, P-3810193 Aveiro, Portugal..
    Energy Efficient Two-Tier Network-Coded Relaying Systems Considering Processing Energy Costs2019In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 68, no 1, p. 999-1003Article in journal (Refereed)
    Abstract [en]

    In this paper, a two-tier network coding (TNC) scheme is proposed for the multi-user multi-relay transmission scenarios. Specifically, TNC is conducted at each individual relay, where two groups of source messages are combined into one network codeword that is forwarded to dual destinations. Finally, two groups of source messages are jointly recovered from different network codewords at the destinations. Both analytical and simulation results demonstrate that the proposed scheme outperforms the current state of art in terms of the energy efficiency (EE). In addition, the impacts of multiple parameters, including the number of users, SNR and relay locations on the average EE have been demonstrated, which provide valuable insights for the system designs of future wireless networks.

  • 26. Zhu, Y.
    et al.
    Hu, Y.
    Schmeink, A.
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Energy Minimization of Mobile Edge Computing Networks with Finite Retransmissions in the Finite Blocklength Regime2019In: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC, Institute of Electrical and Electronics Engineers (IEEE), 2019, article id 8815391Conference paper (Refereed)
    Abstract [en]

    We consider a mobile edge computing network supporting low-latency and ultra reliable services. Task off-loading from the user to the edge server is operated under a truncated retransmission process, i.e., the allowed retransmission times are finite. For such network, we first characterize the end-to-end error probability and the total energy consumption. We subsequently provide a framework design allowing to determine the optimal number of allowed retransmissions and the blocklength for a single transmission/retransmission, where the objective is to minimize the expected total energy consumption while guaranteeing the end-to-end reliability. Via simulation, we confirm our analytical model and evaluated the system performance.

  • 27.
    Liu, Dong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Vu, Minh Thành
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Chatterjee, Saikat
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Rasmussen, Lars Kildehöj
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    ENTROPY-REGULARIZED OPTIMAL TRANSPORT GENERATIVE MODELS2019In: 2019 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH AND SIGNAL PROCESSING (ICASSP), IEEE , 2019, p. 3532-3536Conference paper (Refereed)
    Abstract [en]

    We investigate the use of entropy-regularized optimal transport (EOT) cost in developing generative models to learn implicit distributions. Two generative models are proposed. One uses EOT cost directly in an one-shot optimization problem and the other uses EOT cost iteratively in an adversarial game. The proposed generative models show improved performance over contemporary models on scores of sample based test.

  • 28.
    Zaki, Ahmed
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Mitra, Partha P.
    Cold Spring Harbor Lab, 1 Bungtown Rd, New York, NY USA..
    Rasmussen, Lars Kildehöj
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Chatterjee, Saikat
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Estimate exchange over network is good for distributed hard thresholding pursuit2019In: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 156, p. 1-11Article in journal (Refereed)
    Abstract [en]

    We investigate an existing distributed algorithm for learning sparse signals or data over networks. The algorithm is iterative and exchanges intermediate estimates of a sparse signal over a network. This learning strategy using exchange of intermediate estimates over the network requires a limited communication overhead for information transmission. Our objective in this article is to show that the strategy is good for learning in spite of limited communication. In pursuit of this objective, we first provide a restricted isometry property (RIP)-based theoretical analysis on convergence of the iterative algorithm. Then, using simulations, we show that the algorithm provides competitive performance in learning sparse signals vis-a-vis an existing alternate distributed algorithm. The alternate distributed algorithm exchanges more information including observations and system parameters.

  • 29.
    Dai, Bin
    et al.
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu 610031, Sichuan, Peoples R China..
    Yu, Liman
    Chengdu Text Coll, Sch Econ & Management, Chengdu 611731, Sichuan, Peoples R China..
    Liu, Xuxun
    South China Univ Technol, Sch Elect & Informat Engn, Guangzhou 510641, Guangdong, Peoples R China..
    Ma, Zheng
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering. Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu 610031, Sichuan, Peoples R China..
    Feedback Coding Schemes for the Broadcast Channel With Mutual Secrecy Requirement at the Receivers2019In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 67, no 9, p. 6039-6052Article in journal (Refereed)
    Abstract [en]

    The broadcast channel with mutual secrecy requirement at the receivers (BC-MSR-R) is a basic model characterizing the physical layer security (PLS) in the down-link of the wireless communication systems, where one transmitter sends two independent messages to two receivers via a broadcast channel, and each receiver can successfully decode his/her intended message and wishes to overhear the other one's message. This paper studies how to enhance the already existing secrecy rate region of the BC-MSR-R via receivers' feedback. Specifically, we propose two feedback strategies for the BC-MSR-R, where one uses the feedback to generate pure secret keys protecting the transmitted messages, and the other uses the feedback to generate not only keys but also cooperative messages helping the receivers to improve their decoding performance. Different inner bounds on the secrecy capacity region of the BC-MSR-R with noiseless feedback are constructed according to different feedback strategies, and these bounds are further illustrated by a Dueck-type example.

  • 30.
    Liu, Du
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Flierl, Markus
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Fractional-Pel Accurate Motion-Adaptive Transforms2019In: IEEE Transactions on Image Processing, ISSN 1057-7149, E-ISSN 1941-0042, Vol. 28, no 6, p. 2731-2742, article id 8590746Article in journal (Refereed)
    Abstract [en]

    Fractional-pel accurate motion is widely used in video coding. For subband coding, fractional-pel accuracy is challenging since it is difficult to handle the complex motion field with temporal transforms. In our previous work, we designed integer accurate motion-adaptive transforms (MAT) which can transform integer accurate motion-connected coefficients. In this paper, we extend the integer MAT to fractional-pel accuracy. The integer MAT allows only one reference coefficient to be the lowhand coefficient. In this paper, we design the transform such that it permits multiple references and generates multiple low-band coefficients. In addition, our fractional-pel MAT can incorporate a general interpolation filter into the basis vector, such that the highband coefficient produced by the transform is the same as the prediction error from the interpolation filter. The fractional-pel MAT is always orthonormal. Thus, the energy is preserved by the transform. We compare the proposed fractional-pel MAT, the integer MAT, and the half-pel motion-compensated orthogonal transform (MCOT), while HEVC intra coding is used to encode the temporal subbands. The experimental results show that the proposed fractional-pel MAT outperforms the integer MAT and the half-pel MCOT. The gain achieved by the proposed MAT over the integer MAT can reach up to 1 dB in PSNR.

  • 31.
    Pitarokoilis, Antonios
    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.
    Frequency Diversity versus Channel Training in Latency-Constrained Massive MIMO2019In: 2019 IEEE 20th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Institute of Electrical and Electronics Engineers (IEEE), 2019, article id 8815578Conference paper (Refereed)
    Abstract [en]

    The effect of correlation between neighboring resource blocks (RBs) in the outage probability performance of OFDM-based Massive MIMO systems is investigated. An upper bound on the outage probability, which is the relevant performance metric for latency-constrained communication, of two operations that exploit this correlation structure is derived and compared with the base scenario of orthogonal communication, where the correlation is ignored. It is observed that substantial outage probability improvement can be reaped already when moderate correlation is present. Closed-form upper and lower bounds on the investigated outage probability are derived. The bounds are shown to be tight for a wide range of system parameters and can be used to draw insights on the optimal design of latency-constrained Massive MIMO systems.

  • 32. Liu, G.
    et al.
    Chen, X.
    Ma, Zheng
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering. Southwest Jiaotong University, Chengdu, 610031, China.
    Zhang, X.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Fan, P.
    Full-Duplex and C-RAN Based Multi-Cell Non-Orthogonal Multiple Access over 5G Wireless Networks2019In: ICC 2019 - 2019 IEEE International Conference on Communications (ICC), Institute of Electrical and Electronics Engineers (IEEE), 2019, article id 8761250Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose the full-duplex and cloud radio access network (C-RAN) based multi-cell non-orthogonal multiple access schemes over 5G mobile wireless networks. To cope with the severe intra-cell and inter-cell interferences as well as perform the centralized optimization, we adopt the C-RAN architecture, where the baseband processing and resource management are conducted at a central unit (CU). With the goal of maximizing the weighted sum achievable rate, we formulate the sum rate maximization power allocation problem as a non-convex problem. Thanks to the hidden monotonicity structure of the considered problem, the optimal power allocation algorithm is developed by the monotonic optimization method. Besides, we propose another suboptimal algorithm by employing successive convex approximation method to obtain the close-to-optimal solution with a significantly reduced computational complexity. Extensive simulations are conducted to verify the effectiveness of our proposed power allocation schemes, and confirm the superiority of our proposed C-RAN architecture.

  • 33.
    Liu, Heng
    et al.
    Southwest Jiaotong Univ, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Lu, Jiayi
    Southwest Jiaotong Univ, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Liu, Tianjun
    Southwest Jiaotong Univ, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Hao, Li
    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.
    Generalized Interference Alignment for Multi-cell Cooperative Transmission over Doubly Selective Channels2019In: 2019 IEEE 89TH VEHICULAR TECHNOLOGY CONFERENCE (VTC2019-SPRING), IEEE , 2019Conference paper (Refereed)
    Abstract [en]

    The paper studies the multi-cell cooperation scheme under the time and frequency doubly selective channels, in which the multi-cell co-channel interference are jointly eliminated with the inter-symbol interference to enhance the transmission reception. The basic idea of interference alignment is exploited, with which the link-level interference and network-level interference are aligned to the same dimension before canceled. Instead of assuming the perfect channel information is available at the receivers, an embedded pilot framework is also proposed to track and update the channel state information every short time period, making the proposed scheme more feasible for practical application. Additionally, the pilot design is also discussed and an optimal embedded pilot scheme is derived.

  • 34.
    Nekouei, Ehsan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Tanaka, Takashi
    Univ Texas Austin, Austin, TX 78712 USA..
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Johansson, Karl H.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Information-theoretic approaches to privacy in estimation and control2019In: Annual Reviews in Control, ISSN 1367-5788, E-ISSN 1872-9088, Vol. 47, p. 412-422Article, review/survey (Refereed)
    Abstract [en]

    Network control systems (NCSs) heavily rely on information and communication technologies for sharing information between sensors and controllers as well as controllers and actuators. When estimation, control or actuation tasks in a NCS are performed by an untrusted party, sharing information might result in the leakage of private information. The current paper reviews some of the recent results on the privacy-aware decision-making problems in NCSs. In particular, we focus on static and dynamic decision-making problems wherein privacy is measured using information-theoretic notions. We also review the applications of these problems in smart buildings and smart grids. 

  • 35.
    del Aguila Pla, Pol
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Inverse problems in signal processing: Functional optimization, parameter estimation and machine learning2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Inverse problems arise in any scientific endeavor. Indeed, it is seldom the case that our senses or basic instruments, i.e., the data, provide the answer we seek. It is only by using our understanding of how the world has generated the data, i.e., a model, that we can hope to infer what the data imply. Solving an inverse problem is, simply put, using a model to retrieve the information we seek from the data.

    In signal processing, systems are engineered to generate, process, or transmit signals, i.e., indexed data, in order to achieve some goal. The goal of a specific system could be to use an observed signal and its model to solve an inverse problem. However, the goal could also be to generate a signal so that it reveals a parameter to investigation by inverse problems. Inverse problems and signal processing overlap substantially, and rely on the same set of concepts and tools. This thesis lies at the intersection between them, and presents results in modeling, optimization, statistics, machine learning, biomedical imaging and automatic control.

    The novel scientific content of this thesis is contained in its seven composing publications, which are reproduced in Part II. In five of these, which are mostly motivated by a biomedical imaging application, a set of related optimization and machine learning approaches to source localization under diffusion and convolutional coding models are presented. These are included in Publications A, B, E, F and G, which also include contributions to the modeling and simulation of a specific family of image-based immunoassays. Publication C presents the analysis of a system for clock synchronization between two nodes connected by a channel, which is a problem of utmost relevance in automatic control. The system exploits a specific node design to generate a signal that enables the estimation of the synchronization parameters. In the analysis, substantial contributions to the identifiability of sawtooth signal models under different conditions are made. Finally, Publication D brings to light and proves results that have been largely overlooked by the signal processing community and characterize the information that quantized linear models contain about their location and scale parameters.

  • 36.
    Venkitaraman, Arun
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Frossard, Pascal
    Ecole Polytech Fed Lausanne, Signal Proc Lab LTS4, Lausanne, Switzerland..
    Chatterjee, Saikat
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    KERNEL REGRESSION FOR GRAPH SIGNAL PREDICTION IN PRESENCE OF SPARSE NOISE2019In: 2019 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH AND SIGNAL PROCESSING (ICASSP), IEEE , 2019, p. 5426-5430Conference paper (Refereed)
    Abstract [en]

    In presence of sparse noise we propose kernel regression for predicting output vectors which are smooth over a given graph. Sparse noise models the training outputs being corrupted either with missing samples or large perturbations. The presence of sparse noise is handled using appropriate use of l(1)-norm along-with use of l(2)-norm in a convex cost function. For optimization of the cost function, we propose an iteratively reweighted least-squares (IRLS) approach that is suitable for kernel substitution or kernel trick due to availability of a closed form solution. Simulations using real-world temperature data show efficacy of our proposed method, mainly for limited-size training datasets.

  • 37.
    Shokri-Ghadikolaei, Hossein
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering.
    Ghauch, Hadi
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering. COMELEC Department, Telecom ParisTech, Paris, France.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Learning and Data Selection in Big Datasets2019In: Proceedings of the 36th International Conference on MachineLearning, Long Beach, California, PMLR 97, 2019., 2019Conference paper (Refereed)
    Abstract [en]

    Finding a dataset of minimal cardinality to characterize the optimal parameters of a model is of paramount importance in machine learning and distributed optimization over a network. This paper investigates the compressibility of large datasets. More specifically, we propose a framework that jointly learns the input-output mapping as well as the most representative samples of the dataset (sufficient dataset). Our analytical results show that the cardinality of the sufficient dataset increases sub-linearly with respect to the original dataset size. Numerical evaluations of real datasets reveal a large compressibility, up to 95%, without a noticeable drop in the learnability performance, measured by the generalization error.

  • 38.
    Venkitaraman, Arun
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Zachariah, Dave
    Uppsala Univ, Div Syst & Control, Dept Informat Technol, S-75237 Uppsala, Sweden..
    Learning Sparse Graphs for Prediction of Multivariate Data Processes2019In: IEEE Signal Processing Letters, ISSN 1070-9908, E-ISSN 1558-2361, Vol. 26, no 3, p. 495-499Article in journal (Refereed)
    Abstract [en]

    We address the problem of prediction of multivariate data process using an underlying graph model. We develop a method that learns a sparse partial correlation graph in a tuning-free and computationally efficient manner. Specifically, the graph structure is learned recursively without the need for cross validation or parameter tuning by building upon a hyperparameter-free framework. Our approach does not require the graph to be undirected and also accommodates varying noise levels across different nodes. Experiments using real-world datasets show that the proposed method offers significant performance gains in prediction, in comparison with the graphs frequently associated with these datasets.

  • 39.
    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.

  • 40.
    Kant, Shashi
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering. Ericsson AB.
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. Ericsson AB.
    Bengtsson, Mats
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Göransson, Bo
    Ericsson AB.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems Engineering.
    Low-Complexity OFDM Spectral Precoding2019In: 20th IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC) 2019, 2019, article id 8815554Conference paper (Refereed)
    Abstract [en]

    This paper proposes a new large-scale mask compliant spectral precoder (LS-MSP) for orthogonal frequency division multiplexing systems. In this paper, we first consider a previously proposed mask-compliant spectral precoding scheme that utilizes a generic convex optimization solver which suffers from high computational complexity, notably in large-scale systems. To mitigate the complexity of computing the LS-MSP, we propose a divide-and-conquer approach that breaks the original problem into smaller rank 1 quadratic-constraint problems and each small problem yields closed-form solution. Based on these solutions, we develop three specialized first-order low-complexity algorithms, based on 1) projection on convex sets and 2) the alternating direction method of multipliers. We also develop an algorithm that capitalizes on the closed-form solutions for the rank 1 quadratic constraints, which is referred to as 3) semianalytical spectral precoding. Numerical results show that the proposed LS-MSP techniques outperform previously proposed techniques in terms of the computational burden while complying with the spectrum mask. The results also indicate that 3) typically needs 3 iterations to achieve similar results as 1) and 2) at the expense of a slightly increased computational complexity.

  • 41.
    Yan, Li
    et al.
    Southwest Jiaotong Univ, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Ding, Haichuan
    Univ Michigan, Dept Elect Engn & Comp Sci, Ann Arbor, MI 48109 USA..
    Zhang, Lan
    Univ Florida, Dept Elect & Comp Engn, Gainesville, FL 32611 USA..
    Liu, Jianqing
    Univ Alabama, Dept Elect & Comp Engn, Huntsville, AL 35899 USA..
    Fang, Xuming
    Southwest Jiaotong Univ, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    Fang, Yuguang
    Univ Florida, Dept Elect & Comp Engn, Gainesville, FL 32611 USA..
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Huang, Xiaoxia
    Sun Yat Sen Univ, Sch Elect & Commun Engn, Guangzhou 510006, Guangdong, Peoples R China..
    Machine Learning-Based Handovers for Sub-6 GHz and mmWave Integrated Vehicular Networks2019In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 18, no 10, p. 4873-4885Article in journal (Refereed)
    Abstract [en]

    The integration of sub-6 GHz and millimeter wave (mmWave) bands has a great potential to enable both reliable coverage and high data rate in future vehicular networks. Nevertheless, during mmWave vehicle-to-infrastructure (V2I) handovers, the coverage blindness of directional beams makes it a significant challenge to discover target mmWave remote radio units (mmW-RRUs) whose active beams may radiate somewhere that the handover vehicles are not in. Besides, fast and soft handovers are also urgently needed in vehicular networks. Based on these observations, to solve the target discovery problem, we utilize channel state information (CSI) of sub-6 GHz bands and Kernel-based machine learning (ML) algorithms to predict vehicles' positions and then use them to pre-activate target mmW-RRUs. Considering that the regular movement of vehicles on almost linearly paved roads with finite corner turns will generate some regularity in handovers, to accelerate handovers, we propose to use historical handover data and K-nearest neighbor (KNN) ML algorithms to predict handover decisions without involving time-consuming target selection and beam training processes. To achieve soft handovers, we propose to employ vehicle-to-vehicle (V2V) connections to forward data for V2I links. The theoretical and simulation results are provided to validate the feasibility of the proposed schemes.

  • 42.
    Händel, Peter
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Rönnow, Daniel
    Univ Gavle, Dept Elect Engn Math & Sci, S-80176 Gavle, Sweden..
    Modeling Mixer and Power Amplifier Impairments2019In: IEEE Microwave and Wireless Components Letters, ISSN 1531-1309, E-ISSN 1558-1764, Vol. 29, no 7, p. 441-443Article in journal (Refereed)
    Abstract [en]

    Combating the effects of mixer and power amplifier (PA) imperfections on transmitter performance is crucial for the design of wireless systems. PA compression and in-phase/quadrature imbalance are analyzed for a single-input-single-output transmitter model. The influence of the imperfection on the normalized mean squared error (NMSE) of the transmitter is studied using an analytical framework that relies on the classic Bussgang theory. The study concludes with a closed-form expression for the NMSE that provides insights into the behavior of the transmitter.

  • 43.
    Yang, Ping
    et al.
    Univ Elect Sci & Technol China, Ctr Intelligent Networking & Commun, Chengdu 611731, Sichuan, Peoples R China.;Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Xiao, Yue
    Univ Elect Sci & Technol China, Ctr Intelligent Networking & Commun, Chengdu 611731, Sichuan, Peoples R China.;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.
    Ma, Zheng
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Key Lab Informat Coding & Transmiss, Chengdu 610031, Sichuan, Peoples R China..
    NOMA-Aided Precoded Spatial Modulation for Downlink MIMO Transmissions2019In: IEEE Journal on Selected Topics in Signal Processing, ISSN 1932-4553, E-ISSN 1941-0484, Vol. 13, no 3, p. 729-738Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel multi-user multiple-input multiple-output (MIMO) transmission scheme, called non-orthogonal multiple access (NOMA) aided precoded spatial modulation (PSM) (NOMA-PSM) is proposed for overloaded downlink transmissions. NOMA-PSM beneficially amalgamates the concept of index modulation (IM) and NOMA techniques, and therefore it inherits both the merits of IM with low-complexity transceiver and the advantages of NOMA with high bandwidth efficiency. For the proposed scheme, we develop a pair of low-complexity yet effective detection algorithms by combining the spatial index demodulation and successive interference cancelation. The spectral efficiency (SE), implementation cost, and multi-user interference of NOMA-PSM are evaluated and compared with conventional designs. Furthermore, we derive the mutual information (MI) of the proposed NOMA-PSM to characterize its achievable SE and also obtain a lower bound for simplifying the measurement of MI. Our simulation results show that the proposed NOMA-PSM scheme is capable of achieving considerable performance gains over conventional orthogonal multiple access aid PSM and antenna-groupingbased PSM in wireless MIMO fading channels.

  • 44.
    Ronnow, Daniel
    et al.
    Univ Gävle, Dept Elect Math & Nat Sci, S-80176 Gävle, Sweden..
    Händel, Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Nonlinear Distortion Noise and Linear Attenuation in MIMO Systems-Theory and Application to Multiband Transmitters2019In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 67, no 20, p. 5203-5212Article in journal (Refereed)
    Abstract [en]

    Nonlinear static multiple-input multiple-output (MIMO) systems are analyzed. The matrix formulation of Bussgang's theorem for complex Gaussian signals is rederived and put in the context of the multivariate cumulant series expansion. The attenuation matrix is a function of the input signals' covariance and the covariance of the input and output signals. The covariance of the distortion noise is in addition a function of the output signal's covariance. The effect of the observation bandwidth is discussed. Models of concurrent multiband transmitters are analyzed. For a transmitter with dual non-contiguous hands expressions for the normalized mean square error (NMSE) vs input signal power are derived for uncorrelated, partially correlated, and correlated input signals. A transmitter with arbitrary number of non-contiguous hands is analysed for correlated and uncorrelated signals. In an example, the NMSE is higher when the input signals are correlated than when they are uncorrelated for the same input signal power and it increases with the number of frequency hands. A concurrent dual band amplifier with contiguous bands is analyzed; in this case the NMSE depends on the bandwidth of the aggregated signal.

  • 45.
    Fang, Shu
    et al.
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Zheng, Kaili
    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..
    Yang, Yuming
    Univ Elect Sci & Technol China, Natl Key Lab Sci & Technol Commun, Chengdu 611731, Sichuan, Peoples R China..
    Zeng, Xiaojuan
    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.
    Offset Spatial Modulation and Offset Space Shift Keying: Efficient Designs for Single-RF MIMO Systems2019In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 67, no 8, p. 5434-5444Article in journal (Refereed)
    Abstract [en]

    Spatial modulation (SM) and space shift keying (SSK) techniques have the unique advantages of their single-radio-frequency (RF) structures compared with conventional multiple-input-multiple-output (MIMO) techniques. However, the transmission rates of these techniques are decided by the maximal switching frequency or by the minimal switching time between the RF chain and transmit antennas, which has been a bottleneck for their applications in future broadband wireless communications. To alleviate this problem, we propose a class of novel offset SM (OSM) and offset SSK (OSSK) schemes, with the aid of channel state information (CSI) at the transmitter. Compared with conventional SM and SSK, the proposed OSM and OSSK schemes can reduce the switching frequency of the RF chain, by introducing an offset between the connected RF chain and the index of the spatial modulated antenna. In extreme conditions, the proposed OSM and OSSK can work without RF switching while maintaining the single-RF advantage of conventional SM and SSK schemes. Through theoretical analysis, we also develop the bit-error rate (BER) performance bounds for the proposed two schemes. Finally, our simulation results demonstrate that the proposed OSM and OSSK outperform their counterparts, including conventional SM, SSK, CSI-aided SM, and CSI-aided SSK, while having a simplified RF-switching structure.

  • 46.
    Maros, Marie
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    On Decentralized Tracking with ADMM for Problems with Time-Varying Curvature2019In: arXiv:1903.06492 [math], 2019Conference paper (Refereed)
  • 47.
    Liu, Dong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Cavarec, Baptiste
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Rasmussen, Lars Kildehöj
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Yue, Jing
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    On Dominant Interference in Random Networks and Communication Reliability2019In: ICC 2019 - 2019 IEEE International Conference on Communications (ICC), Institute of Electrical and Electronics Engineers (IEEE), 2019, article id 8761613Conference paper (Refereed)
    Abstract [en]

    In this paper, we study the characteristics of dominant interference power with directional reception in a random network modelled by a Poisson Point Process. Additionally, the Laplace functional of cumulative interference excluding the n dominant interferers is also derived, which turns out to be a generalization of omni-directional reception and complete accumulative interference. As an application of these results, we study the impact of directional receivers in random networks in terms of outage probability and error probability with queue length constraint.

  • 48.
    Venkitaraman, Arun
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Chatterjee, Saikat
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    On Hilbert transform, analytic signal, and modulation analysis for signals over graphs2019In: Signal Processing, ISSN 0165-1684, E-ISSN 1872-7557, Vol. 156, p. 106-115Article in journal (Refereed)
    Abstract [en]

    We propose Hilbert transform and analytic signal construction for signals over graphs. This is motivated by the popularity of Hilbert transform, analytic signal, and modulation analysis in conventional signal processing, and the observation that complementary insight is often obtained by viewing conventional signals in the graph setting. Our definitions of Hilbert transform and analytic signal use a conjugate symmetry-like property exhibited by the graph Fourier transform (GFT), resulting in a 'one-sided' spectrum for the graph analytic signal. The resulting graph Hilbert transform is shown to possess many interesting mathematical properties and also exhibit the ability to highlight anomalies/discontinuities in the graph signal and the nodes across which signal discontinuities occur. Using the graph analytic signal, we further define amplitude, phase, and frequency modulations for a graph signal. We illustrate the proposed concepts by showing applications to synthesized and real-world signals. For example, we show that the graph Hilbert transform can indicate presence of anomalies and that graph analytic signal, and associated amplitude and frequency modulations reveal complementary information in speech signals.

  • 49. Zhang, Yi
    et al.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Han, Shuai
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Meng, Weixiao
    On Precoding and Energy Efficiency of Full-Duplex Millimeter-Wave Relays2019In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 18, no 3, p. 1943-1956Article in journal (Refereed)
    Abstract [en]

    With large available bandwidth, millimeter wave (mm-wave) communications have attracted considerable research interests because of their potential to achieve multi-giga bps rates. However, one of the main challenges for mm-wave is high pathloss. To address this problem, full-duplex (FD) relaying can be used to increase the effective transmission distance and the spectral efficiency. Thus, studying the application of FD relaying in mm-wave communications will be of value. However, one of the main challenges in FD mm-wave relaying is the residual self-interference (SI), which includes line-of-sight (LOS) and non-LOS parts. To eliminate the SI and improve the spectral efficiency, we propose an orthogonal matching pursuit-based SI-cancellation precoding algorithm. Then, we propose an energy consumption model and analyze the energy efficiency performance. We formulate the joint spectral efficiency and energy efficiency optimization problem, which can be transformed into a convex problem. The numerical results show that the FD precoding scheme can effectively eliminate the residual SI and achieve approximately twice the spectral efficiency of the conventional half-duplex system. We also show that in low-spectral-efficiency regions, the optimal energy efficiency can be achieved, but the achievable energy efficiency will decrease in high-spectral-efficiency regions.

  • 50.
    Champati, Jaya Prakash
    et al.
    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), Network and Systems Engineering.
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    On the Distribution of AoI for the GI/GI/1/1 and GI/GI/1/2*Systems: Exact Expressions and Bounds2019In: IEEE CONFERENCE ON COMPUTER COMMUNICATIONS (IEEE INFOCOM 2019), IEEE , 2019, p. 37-45Conference paper (Refereed)
    Abstract [en]

    Since Age of Information (AoI) has been proposed as a metric that quantifies the freshness of information updates in a communication system, there has been a constant effort in understanding and optimizing different statistics of the AoI process for classical queueing systems. In addition to classical queuing systems, more recently, systems with no queue or a unit capacity queue storing the latest packet have been gaining importance as storing and transmitting older packets do not reduce AoI at the receiver. Following this line of research, we study the distribution of AoI for the GI/GI/1/1 and GI/GI/1/2* systems, under non-preemptive scheduling. For any single-source-single-server queueing system, we derive, using sample path analysis, a fundamental result that characterizes the AoI violation probability, and use it to obtain closed-form expressions for D/GI/1/1, M/GI/1/1 as well as systems that use zero-wait policy. Further, when exact results are not tractable, we present a simple methodology for obtaining upper bounds for the violation probability for both GI/GI/1/1 and GI/GI/1/2* systems. An interesting feature of the proposed upper bounds is that, if the departure rate is given, they overestimate the violation probability by at most a value that decreases with the arrival rate. Thus, given the departure rate and for a fixed average service, the bounds are tighter at higher utilization.

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