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  • 1.
    Agrawal, Navneet
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Machine Intelligence in Decoding of Forward Error Correction Codes2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A deep learning algorithm for improving the performance of the Sum-ProductAlgorithm (SPA) based decoders is investigated. The proposed Neural NetworkDecoders (NND) [22] generalizes the SPA by assigning weights to the edges ofthe Tanner graph. We elucidate the peculiar design, training, and working of theNND. We analyze the edge weight’s distribution of the trained NND and providea deeper insight into its working. The training process of NND learns the edgeweights in such a way that the effects of artifacts in the Tanner graph (such ascycles or trapping sets) are mitigated, leading to a significant improvement inperformance over the SPA.We conduct an extensive analysis of the training hyper-parameters affectingthe performance of the NND, and present hypotheses for determining theirappropriate choices for different families and sizes of codes. Experimental resultsare used to verify the hypotheses and rationale presented. Furthermore,we propose a new loss-function that improves performance over the standardcross-entropy loss. We also investigate the limitations of the NND in termsof complexity and performance. Although the SPA based design of the NNDenables faster training and reduced complexity, the design constraints restrictthe neural network to reach its maximum potential. Our experiments show thatthe NND is unable to reach Maximum Likelihood (ML) performance thresholdfor any plausible set of hyper-parameters. However for short length (n 128)High Density Parity Check (HDPC) codes such as Polar or BCH codes, theperformance improvement over the SPA is significant.

  • 2.
    Ainomäe, Ahti
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Distributed Detection in Cognitive Radio Networks2017Licentiate thesis, monograph (Other academic)
    Abstract [en]

    One of the problems with the modern radio communication is the lack of availableradio frequencies. Recent studies have shown that, while the available licensed radiospectrum becomes more occupied, the assigned spectrum is significantly underutilized.To alleviate the situation, cognitive radio (CR) technology has been proposedto provide an opportunistic access to the licensed spectrum areas. Secondary CRsystems need to cyclically detect the presence of a primary user by continuouslysensing the spectrum area of interest. Radiowave propagation effects like fading andshadowing often complicate sensing of spectrum holes. When spectrum sensing isperformed in a cooperative manner, then the resulting sensing performance can beimproved and stabilized.

    In this thesis, two fully distributed and adaptive cooperative Primary User (PU)detection solutions for CR networks are studied.

    In the first part of this thesis we study a distributed energy detection schemewithout using any fusion center. Due to reduced communication such a topologyis more energy efficient. We propose the usage of distributed, diffusion least meansquare (LMS) type of power estimation algorithms with different network topologies.We analyze the resulting energy detection performance by using a commonframework and verify the theoretical findings through simulations.

    In the second part of this thesis we propose a fully distributed detection scheme,based on the largest eigenvalue of adaptively estimated correlation matrices, assumingthat the primary user signal is temporally correlated. Different forms of diffusionLMS algorithms are used for estimating and averaging the correlation matrices overthe CR network. The resulting detection performance is analyzed using a commonframework. In order to obtain analytic results on the detection performance, theadaptive correlation matrix estimates are approximated by a Wishart distribution.The theoretical findings are verified through simulations.

  • 3.
    Ainomäe, Ahti
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. Tallinn University of Technology, Estonia.
    Trump, T.
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Distributed largest eigenvalue detection2017In: 2017 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 3519-3523, article id 7952811Conference paper (Refereed)
    Abstract [en]

    Cognitive radio (CR) systems need to detect the presence of a primary user (PU) signal by continuously sensing the spectrum area of interest. Radiowave propagation effects like fading and shadowing often complicate sensing of spectrum holes because the PU signal can be weak in a particular area. Cooperative spectrum sensing is seen as a prospective solution to enhance the detection of PU signals. In this paper we study distributed spectrum sensing, based on the largest eigenvalue of adaptively estimated correlation matrices (CMs) of received signals. The PU signal is assumed to be temporally correlated. In this paper an Combine and Adapt (CTA) least Mean Square (LMS) diffusion based mean vector estimation scheme is proposed. No fusion center (FC) for estimation or detection is used. We analyse the resulting detection performance and verify the theoretical findings through simulations.

  • 4.
    Alizadeh Khameneh, Mohammad Amin
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. University of Gävle, Gävle, Sweden.
    Rönnow, D.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Isaksson, M.
    A new Block-Structure Modeling Technique for RF Power Amplifiers in a 2x2 MIMO System2017In: 2017 13th International Conference on Advanced Technologies, Systems and Services in Telecommunications, TELSIKS 2017 - Proceeding / [ed] Milovanovic, BD Doncov, NS Stankovic, ZZ Dimitrijevic, TZ, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 224-227Conference paper (Refereed)
    Abstract [en]

    A new block-structure behavioral model is proposed for radio frequency power amplifiers in a 2x2 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.

  • 5.
    Al-Zubaidy, Hussein
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fodor, Viktoria
    KTH, School of Electrical Engineering (EES), Network and Systems engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dán, György
    KTH, School of Electrical Engineering (EES), Network and Systems engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Flierl, Markus
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Reliable Video Streaming With Strict Playout Deadline in Multihop Wireless Networks2017In: IEEE transactions on multimedia, ISSN 1520-9210, E-ISSN 1941-0077, Vol. 19, no 10, p. 2238-2251Article in journal (Refereed)
    Abstract [en]

    Motivated by emerging vision-based intelligent services, we consider the problem of rate adaptation for high-quality and low-delay visual information delivery over wireless networks using scalable video coding. Rate adaptation in this setting is inherently challenging due to the interplay between the variability of the wireless channels, the queuing at the network nodes, and the frame-based decoding and playback of the video content at the receiver at very short time scales. To address the problem, we propose a low-complexity model-based rate adaptation algorithm for scalable video streaming systems, building on a novel performance model based on stochastic network calculus. We validate the analytic model using extensive simulations. We show that it allows fast near-optimal rate adaptation for fixed transmission paths, as well as cross-layer optimized routing and video rate adaptation in mesh networks, with less than 10% quality degradation compared to the best achievable performance.

  • 6. Amin, Shoaib
    et al.
    van Moer, Wendy
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Ronnow, Daniel
    Rebuttal to "On Dual-Band Amplifications Using Dual Two-Tones Clarifications and Discussions"2017In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 66, no 10, p. 2795-2797Article in journal (Refereed)
    Abstract [en]

    This rebuttal is to "On dual-band amplifications using dual two-tone: Clarifications and discussion." In the following, we provide our reply.

  • 7.
    Anxionnat, Adrien
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Segmentation of high frequency 3D ultrasound images for skin disease characterization2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This work is rooted in a need for dermatologists to explore skin characteristicsin depth. The inuence of skin disease such as acne in dermal tissues is stilla complex task to assess. Among the possibilities, high frequency ultrasoundimaging is a paradigm shift to probe and characterizes upper and deep dermis.For this purpose, a cohort of 58 high-frequency 3D images has been acquiredby the French laboratory Pierre Fabre in order to study acne vulgaris disease.This common skin disorder is a societal challenge and burden aecting late adolescentsacross the world. The medical protocol developed by Pierre Fabre wasto screen a lesion every day during 9 days for dierent patients with ultrasoundimaging. The provided data features skin epidermis and dermis structure witha fantastic resolution. The strategy we led to study these data can be explainedin three steps. First, epidermis surface is detected among artifacts and noisethanks to a robust level-set algorithm. Secondly, acne spots are located on theresulting height map and associated to each other among the data by computingand thresholding a local variance. And eventually potential inammatorydermal cavities related to each lesion are geometrically and statistically characterizedin order to assess the evolution of the disease. The results presentan automatic algorithm which permits dermatologists to screen acne vulgarislesions and to characterize them in a complete data set. It can hence be a powerfultoolbox to assess the eciency of a treatment.

  • 8. Ashraf, Shehzad Ali
    et al.
    Wang, Y.-P. Eric
    Eldessoki, Sameh
    Holfeld, Bernd
    Parruca, Donald
    Serror, Martin
    Gross, James
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    From Radio Design to System Evaluations for Ultra-Reliable and Low-Latency Communication2017In: European Wireless 2017 - 23rd European Wireless Conference, 2017, article id 8011336Conference paper (Refereed)
    Abstract [en]

    Ultra-reliable and low-latency communication is the enabler for many new use cases, including wireless industrial automation. Fulfilling varying requirements of these use cases demands a flexible radio design. To address this, a holistic approach needs to be adopted. Therefore, this paper presents the radio access concepts affecting the communication reliability and latency, and comprehensively evaluates link and system level considerations through simulations. In particular, we describe the choice of suitable modulation and coding schemes, and discuss the impact of different numerologies and waveform candidates. We also point out the key principles for radio frame design to reduce the end-to-end latency. The presented concepts are then used to evaluate the performance at system level for an industrial scenario. It is shown that by an appropriate design of the radio interface for 5G system, the required low-latency and high reliability for industrial applications and many other use cases can be achieved.

  • 9. Bao, J.
    et al.
    Ma, Z.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Tsiftsis, T. A.
    Zhu, Z.
    Performance analysis of uplink sparse code multiple access with iterative multiuser receiver2017In: 2017 IEEE International Conference on Communications, ICC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7996537Conference paper (Refereed)
    Abstract [en]

    This paper investigates the asymptotic performance of bit-interleaved coded modulation (BICM) with iterative multiuser detection and decoding in uplink sparse code multiple access (SCMA) systems. The extrinsic information transfer (EXIT) characteristics analysis of the joint multiuser detector for SCMA is provided, and shows that the average detection reliability for multiple users converges to the single-user case, if ideal feedback from the decoder is available to the detector. We develop a tight analytical bound on the convolutionally encoded bit-error rate (BER) for independent Rayleigh fadings, based on the single-user bound with arbitrary multidimensional constellations. Moreover, we analyze the achievable coding and diversity gains of the SCMA-BICM system with iterative receiver. Simulations are carried out to verify the effectiveness of the analysis.

  • 10.
    Björsell, Niclas
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics..
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Large Antenna Array for Low-Latency and Ultra-Reliable Communication2017Conference paper (Other academic)
  • 11. Bose, Subhojyoti
    et al.
    Gupta, Amit K.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    On The Noise And Power Performance Of A Shoe-Mounted Multi-Imu Inertial Positioning System2017In: 2017 INTERNATIONAL CONFERENCE ON INDOOR POSITIONING AND INDOOR NAVIGATION (IPIN), IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    Shoe-mounted inertial navigation systems, aka pedestrian dead reckoning or PDR sensors, are being preferred for pedestrian navigation because of the accuracy offered by them. Such shoe sensors are, for example, the obvious choice for real time location systems of first responders. The opensource platform OpenShoe has reported application of multiple IMUs in shoe-mounted PDR sensors to enhance noise performance. In this paper, we present an experimental study of the noise performance and the operating clocks based power consumption of multi-IMU platforms. The noise performances of a multi-IMU system with different combinations of IMUs are studied. It is observed that four-IMU system is best optimized for cost, area and power. Experiments with varying operating clocks frequency are performed on an in-house four-IMU shoe-mounted inertial navigation module (the Oblu module). Based on the outcome, power-optimized operating clock frequencies are obtained. Thus the overall study suggests that by selecting a well-designed operating point, a multi-IMU system can be made cost, size and power efficient without practically affecting its superior positioning performance.

  • 12.
    Cao, Le Phuong
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Optimal transmit strategy for MIMO channels with joint sum and per-antenna power constraints2017In: 2017 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), IEEE, 2017, p. 3569-3573Conference paper (Refereed)
    Abstract [en]

    This paper studies optimal transmit strategies for multiple-input multiple-output (MIMO) Gaussian channels with joint sum and per-antenna power constraints. It is shown that if an unconstraint optimal 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. Finally, a numerical example is provided to illustrate the theoretical results.

  • 13.
    Cao, Phuong
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Oechtering, Tobias
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Optimal Trade-off Between Transmission Rate andSecrecy Rate in Gaussian MISO Wiretap Channels2017Conference paper (Refereed)
    Abstract [en]

    The future wireless networks require both high data transmission rates and secure communications. However, there exists a trade-off between secure and non-secure rates since only a fraction of the maximal achievable reliable rate in a wiretap channel can be considered as secure. This paper studies the optimal transmit strategies that achieve the optimal trade-off between the communication rate and secrecy rate for the MISO wiretap channels with different power constraint settings including sum power constraint only, per-antenna power constraints only, and joint sum and per-antenna power constraints. First, a necessary and sufficient condition to ensure a positive secrecy capacity is shown. After that, closed-form solutions to find an optimal transmit strategy of related problems are derived. This provides a parametrization of the boundary of the maximal achievable rate and secrecy rate without additional time-sharing. The optimal trade-off is characterized by the convex hull of the region. Lastly, the results are illustrated by numerical examples.

  • 14.
    Carlsson, Håkan
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Skog, Isaac
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Jaldén, Joakim
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    On-The-Fly Geometric Calibration of Inertial Sensor Arrays2017In: 2017 INTERNATIONAL CONFERENCE ON INDOOR POSITIONING AND INDOOR NAVIGATION (IPIN), 2017Conference paper (Refereed)
    Abstract [en]

    We present a maximum likelihood estimator for estimating the positions of accelerometers in an inertial sensor array. This method simultaneously estimates the positions of the accelerometers and the motion dynamics of the inertial sensor array and, therefore, does not require a predefined motion sequence nor any external equipment. Using an iterative block coordinate descent optimization strategy, the calibration problem can be solved with a complexity that is linear in the number of time samples. The proposed method is evaluated by Monte-Carlo simulations of an inertial sensor array built out of 32 inertial measurement units. The simulation results show that, if the array experiences sufficient dynamics, the position error is inversely proportional to the number of time samples used in the calibration sequence. Further, results show that for the considered array geometry and motion dynamics in the order of 2000 degrees/s and 2000 degrees/s(2), the positions of the accelerometers can be estimated with an accuracy in the order of 10(-6) m using only 1000 time samples. This enables fast on-the-fly calibration of the geometric errors in an inertial sensor array by simply twisting it by hand for a few seconds.

  • 15. Caso, G.
    et al.
    De Nardis, L.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Di Benedetto, M.
    Cooperative Sensing of Spectrum Opportunities2015In: Opportunistic Spectrum Sharing and White Space Access: The Practical Reality, Wiley-Blackwell, 2015, p. 143-165Chapter in book (Other academic)
    Abstract [en]

    Reliability and availability of sensing information gathered from local spectrum sensing (LSS) by a single Cognitive Radio is strongly affected by the propagation conditions, period of sensing, and geographical position of the device. For this reason, cooperative spectrum sensing (CSS) was largely proposed in order to improve LSS performance by using cooperation between Secondary Users (SUs). The goal of this chapter is to provide a general analysis on CSS for cognitive radio networks (CRNs). Firstly, the theoretical system model for centralized CSS is introduced, together with a preliminary discussion on several fusion rules and operative modes. Moreover, three main aspects of CSS that substantially differentiate the theoretical model from realistic application scenarios are analyzed: (i) the presence of spatiotemporal correlation between decisions by different SUs; (ii) the possible mobility of SUs; and (iii) the nonideality of the control channel between the SUs and the Fusion Center (FC). For each aspect, a possible practical solution for network organization is presented, showing that, in particular for the first two aspects, cluster-based CSS, in which sensing SUs are properly chosen, could mitigate the impact of such realistic assumptions.

  • 16.
    Cavarec, Baptiste
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Schedule based self localization of asynchronous wireless nodes with experimental validation2017In: 2017 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 5975-5979, article id 7953303Conference paper (Refereed)
    Abstract [en]

    In this paper we have proposed clock error mitigation from the measurements in the scheduled based self localization system. We propose measurement model with clock errors while following a scheduled transmission among anchor nodes. Further, RLS algorithm is proposed to estimate clock error and to calibrate measurements of self localizing node against relative clock errors of anchor nodes. A full-scale experimental validation is provided based on commercial off-the-shelf UWB radios under IEEE-standardized protocols.

  • 17.
    Celebi, Hasan Basri
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Arslan, H.
    A joint blind carrier frequency and phase offset detector and modulation order identifier for MPSK signals2010In: 2010 IEEE Radio and Wireless Symposium (RWS), IEEE conference proceedings, 2010, p. 348-351Conference paper (Refereed)
    Abstract [en]

    In this paper, a new blind carrier frequency and phase offset detector, and modulation order identifier are presented for phase shift keying (PSK) signals. These operations are intermediate steps between signal detection and demodulation, and play a key role in various military and non- military applications. As compared with previous related approaches, the proposed algorithm provides a fully blind phase-frequency offset detector structure without having the knowledge of modulation order. After correcting the frequency offset, the modulation order is detected by investigating the probability density function (PDF) of the phase distribution.

  • 18.
    Celebi, Hasan Basri
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Durak-Ata, L.
    Spectrum sensing with periodic non-uniform sampling2015Conference paper (Refereed)
    Abstract [en]

    New wireless communication technologies increase the demand for spectrum sensing. However due to the limitations of analogue-to-digital converters, sampling a wide spectrum still remains as a major problem. In this paper, a method for estimating the power spectrum density (PSD) from multi-coset (MC) samples, which is a special sub-Nyquist sampling method, is explained. In order to see the feasibility of the method, wide sense spectrum measurements are taken from a vector signal analyzer and each measurement is MC sampled. Then the PSD estimation is compared with the original PSD of the signal. False alarm rates for different variations are analyzed.

  • 19.
    Celebi, Hasan Basri
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Durak-Ata, L.
    Celebi, H.
    Multi-coset sampling and reconstruction of signals: Exploiting sparsity in spectrum monitoring2013Conference paper (Refereed)
    Abstract [en]

    We present an analytical representation of multi-coset sampling (MCS) and implement the proposed scheme on spectrum data to analyze the effect of MCS that requires less samples. Sampling pattern (SP) selection, which is one of the most significant phases of MCS, is investigated and the effect of the SP on reconstruction matrices and reconstruction process of the signal is analyzed. Different algorithms, which aim to find the optimum SP, are presented and their performances are compared. In order to present the feasibility of the process, MCS is implemented to measurements captured by a spectrum analyzer. The wideband spectrum measurements are obtained over 700-3000 MHz. They are sub-sampled and reconstructed again, so that the RMSE values of the reconstructed signals are evaluated. Effects of the SP search algorithms on the reconstruction process are analyzed for the spectrum monitoring application.

  • 20.
    Celebi, Hasan Basri
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Guzelgoz, S.
    Guzel, T.
    Arslan, H.
    Noise and channel statistics of indoor power line networks2011In: 2011 18th International Conference on Telecommunications, IEEE conference proceedings, 2011, p. 523-527Conference paper (Refereed)
    Abstract [en]

    Power line communication (PLC) channels may have entirely different physical characteristics. In order to establish reliable communication systems operating in power line networks (PLNs), characteristics of power line channel have to be investigated very carefully. In this paper, noise and multipath characteristics of PLC channels are examined. A unique experimental setup is established for noise measurements and a simulation environment is prepared for multipath analysis for indoor PLNs. Results of the measurements and simulations are presented. Besides the investigation of some specific PLNs, impact of the physical characteristics of different PLC networks on the channel delay spread parameter, namely root-mean-squared (RMS) delay spread, are studied statistically.

  • 21.
    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.

  • 22.
    Chevatco, Vladimir
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Calibration of Vibration sensors - Evaluation and Effectivization2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, the calibration process of a geophone based vibration sensor istreated and optimised. The purpose of calibration is to estimate the physicalparameters of the system in the form of gain, damping and eigenfrequency.The geophone is calibrated on a shaker, and this thesis deals with the choiceof input signals and parameter estimation methods. Three dierent inputsignals are evaluated, and a new calibration process based on a multi-toneexcitation coupled with system identication methods for parameter estimationis proposed.

  • 23.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Joint node deployment and wireless energy transfer scheduling for immortal sensor networks2017In: 2017 15th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks, WiOpt 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7959918Conference paper (Refereed)
    Abstract [en]

    The lifetime of a wireless sensor network (WSN) is limited by the lifetime of the individual sensor nodes. A promising technique to extend the lifetime of the nodes is wireless energy transfer. The WSN lifetime can also be extended by exploiting the redundancy in the nodes' deployment, which allows the implementation of duty-cycling mechanisms. In this paper, the joint problem of optimal sensor node deployment and WET scheduling is investigated. Such a problem is formulated as an integer optimization whose solution is challenging due to the binary decision variables and non-linear constraints. To solve the problem, an approach based on two steps is proposed. First, the necessary condition for which the WSN is immortal is established. Based on this result, an algorithm to solve the node deployment problem is developed. Then, the optimal WET scheduling is given by a scheduling algorithm. The WSN is shown to be immortal from a networking point of view, given the optimal deployment and WET scheduling. Theoretical results show that the proposed algorithm achieves the optimal node deployment in terms of the number of deployed nodes. In the simulation, it is shown that the proposed algorithm reduces significantly the number of nodes to deploy compared to a random-based approach. The results also suggest that, under such deployment, the optimal scheduling and WET can make WSNs immortal.

  • 24.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Ozcelikkale, A.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Optimal energy beamforming and data routing for immortal wireless sensor networks2017In: 2017 IEEE International Conference on Communications, ICC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7996326Conference paper (Refereed)
    Abstract [en]

    Wireless sensor networks (WSNs) consist of energy limited sensor nodes, which limits the network lifetime. Such a lifetime can be prolonged by employing the emerging technology of wireless energy transfer (WET). In WET systems, the sensor nodes can harvest wireless energy from wireless charger, which can use energy beamforming to improve the efficiency. In this paper, a scenario where dedicated wireless chargers with multiple antennas use energy beamforming to charge sensor nodes is considered. The energy beamforming is coupled with the energy consumption of sensor nodes in terms of data routing, which is one novelty of the paper. The energy beamforming and the data routing are jointly optimized by a non-convex optimization problem. This problem is transformed into a semidefinite optimization problem, for which strong duality is proved, and thus the optimal solution exists. It is shown that the optimal solution of the semi-definite programming problem allows to derive the optimal solution of the original problem. The analytical and numerical results show that optimal energy beamforming gives two times better monitoring performance than that of WET without using energy beamforming.

  • 25. Fotedar, G.
    et al.
    Aditya Gaonkar, P.
    Chatterjee, Saikat
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Ghosh, P. K.
    Automatic recognition of social roles using long term role transitions in small group interactions2016In: Proceedings of the Annual Conference of the International Speech Communication Association, INTERSPEECH, 2016, p. 2065-2069Conference paper (Refereed)
    Abstract [en]

    Recognition of social roles in small group interactions is challenging because of the presence of disfluency in speech, frequent overlaps between speakers, short speaker turns and the need for reliable data annotation. In this work, we consider the problem of recognizing four roles, namely Gatekeeper, Protagonist, Neutral, and Supporter in small group interactions in AMI corpus. In general, Gatekeeper and Protagonist roles occur less frequently compared to Neutral, and Supporter. In this work, we exploit role transitions across segments in a meeting by incorporating role transition probabilities and formulating the role recognition as a decoding problem over the sequence of segments in an interaction. Experiments are performed in a five fold cross validation setup using acoustic, lexical and structural features with precision, recall and F-score as the performance metrics. The results reveal that precision averaged across all folds and different feature combinations improves in the case of Gatekeeper and Protagonist by 13.64% and 12.75% when the role transition information is used which in turn improves the F-score for Gatekeeper by 6.58% while the F-scores for the rest of the roles do not change significantly.

  • 26.
    Gerami, Majid
    et al.
    KTH, School of Electrical Engineering (EES).
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Salimi, S.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Optimal secure partial-repair in distributed storage systems2017In: 2017 51st Annual Conference on Information Sciences and Systems, CISS 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 7926093Conference paper (Refereed)
    Abstract [en]

    Consider a distributed storage system where parts of the source file fragments in storage nodes are lost. We denote a storage node that lost a part of its fragments as a faulty storage node and a storage node that lost non of its fragment as a complete storage node. In a process, termed as partial repair, a set of storage nodes (among faulty and complete storage nodes) transmit repairing fragments to other faulty storage nodes to recover the lost fragments. We first investigate the optimal partial repair in which the required bandwidth for recovering the lost fragments is minimal. Next, we assume that an eavesdropper wiretaps a subset of links connecting storage nodes, and overhears a number of repairing fragments. We then study optimal secure partial-repair in which the partial-repair bandwidth is minimal and the eavesdropper obtains no information about the source file by overhearing the repairing fragments. We propose optimal secure codes for exact partial-repair in a special scenario.

  • 27.
    Gerami, Majid
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Two-Layer Coding in Distributed Storage Systems With Partial Node Failure/Repair2017In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 21, no 4, p. 726-729Article in journal (Refereed)
    Abstract [en]

    We a distributed storage system where parts of the stored packets in storage nodes are subject to being lost. In a process, termed as the partial repair, the lost packets in a faulty node are recovered by the transmitted packets from other storage nodes and the available packets in the faulty node. To improve reliability of the stored data, and reduce the transmission costs, we propose a scheme that implements two-layer coding for storing files in the system. We study the minimum possible partial-repair bandwidth, and the codes that achieve the optimal bound.

  • 28.
    Ghauch, Hadi
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Imtiaz, Sahar
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Koudouridis, George
    Gross, James
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fairness and User Assignment in Cloud-RAN2017In: 2017 IEEE 86TH VEHICULAR TECHNOLOGY CONFERENCE (VTC-FALL), 2017Conference paper (Refereed)
    Abstract [en]

    In this paper, we extend our previous work on user assignment in Cloud-RAN, where we proposed an algorithm for user assignment (UA). We motivate the inherent fairness issue that is present in the latter UA scheme, since some users in the system will never get served. To improve the fairness, we propose that the UA scheme is preceded by a user scheduling step which aims at selecting at any time the users that should be considered by the UA algorithm for scheduling (in the next time slot). Two user scheduling approaches have been studied. The first scheme improves the minimum throughput (MT), by selecting at any time the users with the lowest throughput. The second scheme is based on round-robin (RR) scheduling, where the set of potentially scheduled users for the next slot, is done by excluding all the previously served users, in that round. Moreover, the subset of actual users to be served, is determined using the UA algorithm. We evaluate their fairness and sumrate performance, via extensive simulations. While one might have expected a tradeoff between the sum-rate performance and fairness, our results show that MT improves both metrics, when compared to the original UA algorithm (without fairness), for some choice of parameter values. This implies that both fairness and aggregate system performance can be improved, by a careful choice of the number of assigned and served users.

  • 29.
    Ghauch, Hadi
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Kim, Taejoon
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Sum-Rate Maximization in Sub-28-GHz Millimeter-Wave MIMO Interfering Networks2017In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 35, no 7, p. 1649-1662Article in journal (Refereed)
    Abstract [en]

    MIMO systems in the lower part of the millimetre-wave (mmWave) spectrum band (i.e., below 28 GHz) do not exhibit enough directivity and selectively, as compared to their counterparts in higher bands of the spectrum (i.e., above 60 GHz), and thus still suffer from the detrimental effect of interference, on the system sum rate. As such systems exhibit large numbers of antennas and short coherence times for the channel, traditional methods of distributed coordination are ill-suited, and the resulting communication overhead would offset the gains of coordination. In this paper, we propose algorithms for tackling the sum-rate maximization problem that are designed to address the above-mentioned limitations. We derive a lower bound on the sum rate, a so-called difference of log and trace (DLT) bound, shed light on its tightness, and highlight its decoupled nature at both the transmitters and receivers. Moreover, we derive the solution to each of the subproblems that we dub non-homogeneous waterfilling (a variation on the MIMO waterfilling solution), and underline an inherent desirable feature: its ability to turn-OFF streams exhibiting low SINR, and contribute to greatly speeding up the convergence of the proposed algorithm. We then show the convergence of the resulting algorithm, max-DLT, to a stationary point of the DLT bound. Finally, we rely on extensive simulations of various network configurations, to establish the fast-converging nature of our proposed schemes, and thus their suitability for addressing the short coherence interval, as well as the increased system dimensions, arising when managing interference in lower bands of the mmWave spectrum. Moreover, our results suggest that interference management still brings about significant performance gains, especially in dense deployments.

  • 30.
    Gholami, Mohammad Reza
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Keskin, M. F.
    Bilkent University, Ankara, Turkey.
    Gezici, Sinan
    Bilkent University, Ankara, Turkey.
    Jansson, Magnus
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Cooperative Positioning in Wireless Networks2016In: Wiley Encyclopedia of Electrical and Electronics Engineering, John Wiley & Sons, 2016, p. 1-19Chapter in book (Refereed)
    Abstract [en]

    In this article, we study cooperative positioning in wireless networks in which target nodes at unknown locations locally collaborate with each other to find their locations. We review different models available for positioning and categorize the model-based algorithms in two groups: centralized and distributed. We then investigate a lower bound on the variance of unbiased estimators, namely the Cramer–Rao lower bound, which is a common benchmark in the positioning literature. We finally discuss some open problems and research topics in the area of positioning that are worth exploring in future studies.

  • 31. Guzel, T.
    et al.
    Ustunel, E.
    Celebi, Hasan Basri
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Delic, H.
    Mihcak, K.
    Noise Modeling and OFDM Receiver Design in Power-Line Communication2011In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 1937-4208, Vol. 26, no 4, p. 2735-2742Article in journal (Refereed)
    Abstract [en]

    Electromagnetic interference, man-made noise, and multipath effects are the main causes of bit errors in power-line communication. In this paper, it is experimentally demonstrated that the power-line noise distribution is non-Gaussian below 12 MHz, and close to Gaussian in the 12-50 MHz range. The noise-amplitude distribution of each individual frequency in the spectrum is analyzed and the generalized Gaussian distribution (GGD) is introduced as a suitable noise model across the spectrum. Orthogonal frequency-division multiplexing (OFDM) with convolutional coding and soft-Viterbi decoding is adopted to design a GGD-optimal communication system. Simulations demonstrate the performance improvement offered over the Gaussian-optimal receiver. The channel simulations are verified through measurements.

  • 32.
    Honoré, Antoine
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Machine Learning for Neonatal Early Warning Signs2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cardio-respiratory dysfunction, sepsis and necrotizing enterocolitis are responsible for a large numberof deaths in the neonatal population. Despite ecient monitoring and screening in Intensive CareUnits, diagnosis prior to clinical symptoms remains a dicult task. Based on Heart Rate Monitoring,the state-of-the-art HeRO system indicates the risk for sepsis and has already proven its ability toreduce mortality in the neonatal ICU. Recent studies have shown that a particular respiratory behaviorknown as ABD-events, can be used as a physiomarker for sepsis and is therefore an early warningsign. Detecting ABD-events is currently done by simple thresholding techniques. Based on cardiorespiratorydata and hindsight from previous patients, we aim at improving the early warning systemby applying machine learning algorithms. Data with higher frequency than those used in the HeROsystem and biological samples are still to be collected, but still, using low frequency data, we managedto obtain a specicity (true positive) of 70% and a sensitivity (true negative) of 65% on manuallylabeled events. In this report, the theoretical framework is presented along with the practical issuesencountered during the project.

  • 33. Hu, Xing
    et al.
    Ma, Linhua
    Huang, Shaocheng
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Huang, Jinke
    Sun, Kangning
    Huang, Tianyu
    Performance analysis and saturation bound research of cyclic-quorum multichannel MAC protocol based on Markov chain model2017In: KSII TRANSACTIONS ON INTERNET AND INFORMATION SYSTEMS, ISSN 1976-7277, Vol. 11, no 8, p. 3862-3888Article in journal (Refereed)
    Abstract [en]

    In high diversity node situation, single-channel MAC protocols suffer from many collisions. To solve this problem, the research of multichannel MAC protocol has become a hotspot. And the cyclic quorum-based multichannel (CQM) MAC protocol outperformed others owing to its high frequency utilization. In addition, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQM MAC protocol, a Markov chain model, which combines the channel hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The metrics (throughput and average packet transmission delay) are calculated in performance analysis, with respect to node number, packet rate, channel slot length and channel number. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm (BSA). Finally, the Markov chain model and saturation bound are verified by Qualnet platform. And the simulation results show that the analytic and simulation results match very well.

  • 34. Hu, Xing
    et al.
    Ma, Linhua
    Huang, Shaocheng
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Huang, Tianyu
    Liu, Shiping
    Dynamic Channel Slot Allocation Scheme and Performance Analysis of Cyclic Quorum Multichannel MAC Protocol2017In: Mathematical problems in engineering (Print), ISSN 1024-123X, E-ISSN 1563-5147, article id 8580913Article in journal (Refereed)
    Abstract [en]

    In high diversity node situation, multichannel MAC protocol can improve the frequency efficiency, owing to fewer collisions compared with single-channel MAC protocol. And the performance of cyclic quorum-based multichannel (CQM) MAC protocol is outstanding. Based on cyclic quorum system and channel slot allocation, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQMMAC protocol, a Markov chain model, which combines the channel-hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm. In addition, to improve the performance of CQM protocol in unsaturation situation, a dynamic channel slot allocation of CQM(DCQM) protocol is proposed, based on wavelet neural network. Finally, the performance of CQM protocol and DCQM protocol is simulated by Qualnet platform. And the simulation results show that the analytic and simulation results match very well; the DCQM performs better in unsaturation situation.

  • 35. Huang, J.
    et al.
    Fei, Z.
    Cao, C.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Jia, D.
    On-Line Fountain Codes with Unequal Error Protection2017In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 21, no 6, p. 1225-1228, article id 7857018Article in journal (Refereed)
    Abstract [en]

    A new encoding scheme for on-line fountain codes is proposed to provide unequal error protection (UEP) for source symbols. Both the weighted-selection strategy and the expanding-window strategy are used to achieve the UEP property. We analyze the bound of overhead to demonstrate the performance. We also make comparisons with on-line fountain codes that provide equal error protection. Simulation results show that with the proposed scheme, UEP is achieved, where the most important symbols are recovered faster than the least important symbols.

  • 36.
    Huang, Jin
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    State of the art on road traffic sensing and learning based on mobile user network log data2018In: Neurocomputing, ISSN 0925-2312, E-ISSN 1872-8286, Vol. 278, p. 110-118Article in journal (Refereed)
    Abstract [en]

    With the improvement of the storage and big data processing technology, mobile operators are able to extract and store a large amount of mobile network generated user behavior data, in order to develop various intelligent applications. One interesting application based on these data is traffic sensing, which uses techniques of learning human mobility patterns from updated location information in network interaction log data. Mobile networks, under which a huge amount of frequently updated location information of mobile users are tracked, can provide complete coverage to estimate traffic condition on roads and highways. This paper studies potential challenges and opportunities in intelligent traffic sensing from the data science point of view with mobile network generated data. Firstly, we classify the data resources available in the commercial radio network according to different taxonomy criteria. Then we outline the broken-down problems that fit in the framework of traffic sensing based on mobile user network log data. We study the existing data processing and learning algorithms on extracting traffic condition information from a large amount of mobile network log data. Finally we make suggestion on potential future work for traffic sensing on data from mobile networks. We believe the techniques and insights provided here will inspire the research community in data science to develop the machine learning models of traffic sensing on the widely collected mobile user behavior data.

  • 37. Huang, Tianyu
    et al.
    Ma, Linhua
    Hu, Xing
    Huang, Shaocheng
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Liu, Shiping
    2D autoregressive model-based dynamic correlated massive MU-MIMO channel simulator2017In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 53, no 17Article in journal (Refereed)
    Abstract [en]

    To design a dynamic correlated channel simulator which can precisely depict the space-time correlation properties and be suitable for the massive multi-user multiple-input multiple-output (MU-MIMO) system, a 2D autoregressive (2D AR) model-based method is proposed. Specifically, by exploiting stationarity in space-time domain, the authors use 2D AR method to create the space-time channel matrices of every user separately. In this way, the space-time dimension of the simulated channel can be modified flexibly without rebuilding the 2D AR model, and spatial correlation matrix with excessively big size is not necessary to guarantee the accuracy of the proposed simulator, making it suitable for massive MU-MIMO system. Simulation results verify the advantages of the proposed simulator.

  • 38.
    Imtiaz, Sahar
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Ghauch, Hadi
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Koudouridis, George
    Gross, James
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Random Forests Resource Allocation for 5G Systems: Performance and Robustness Study2018Conference paper (Refereed)
  • 39.
    Imtiaz, Sahar
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Ghauch, Hadi
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Ur Rahman, M. M.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Koudouridis, Georgios
    KTH, School of Electrical Engineering (EES), Communication Networks. Huawei Technologies Sweden R&D Center.
    Gross, James
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Learning-based resource allocation scheme for TDD-based 5G CRAN system2016In: MSWiM 2016 - Proceedings of the 19th ACM International Conference on Modeling, Analysis and Simulation of Wireless and Mobile Systems, ACM Press, 2016, p. 176-185Conference paper (Refereed)
    Abstract [en]

    Provision of high data rates with always-onconnectivity to high mobility users is one of the motivations for design of fifth generation (5G) systems. High system capacity can be achieved by coordination between large number of antennas, which is done using the cloud radio access network (CRAN) design in 5G systems. In terms of baseband processing, allocation of appropriate resources to the users is necessary to achieve high system capacity, for which the state of the art uses the users' channel state information (CSI); however, they do not take into account the associated overhead, which poses a major bottleneck for the effective system performance. In contrast to this approach, this paper proposes the use of machine learning for allocating resources to high mobility users using only their position estimates. Specifically, the 'random forest' algorithm, a supervised machine learning technique, is used to design a learning-based resource allocation scheme by exploiting the relationships between the system parameters and the users' position estimates. In this way, the overhead for CSI acquisition is avoided by using the position estimates instead, with better spectrum utilization. While the initial numerical investigations, with minimum number of users in the system, show that the proposed learning-based scheme achieves 86% of the efficiency achieved by the perfect CSI-based scheme, if the effect of overhead is factored in, the proposed scheme performs better than the CSI-based approach. In a realistic scenario, with multiple users in the system, the significant increase in overhead for the CSI-based scheme leads to a performance gain of 100%, or more, by using the proposed scheme, and thus proving the proposed scheme to be more efficient in terms of system performance.

  • 40.
    Isaksson, Martin
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    StemNet: A Temporally Trained Fully Convolutional Network for Segmentation of Muscular Stem Cells2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In biomedical research, time-lapse microscopy is an important tool to be able tostudy processes which are too slow for humans to observe. This technique ispowerful since it gives information about how parameters of single cells changeover time.The problem to be solved in this project is to segment MuSCs (Muscular Stem Cells)in images and to classify them. This is done by using a deep neural network trainedusing supervised learning. The network is inspired by the architecture of the U-net,but extended by using temporal data to see if it can increase its performance. Thenetwork is trained on images from the time-lapse sequence, where the temporalaspect is used to create a short-term memory for the network. The results arecompared to a network of the same architecture but without the temporal aspect inthe training.The temporal approach shows that the network learns faster what is roughly aMuSC and what is not, but in the end it gives a slightly higher and more accurateclassification of MuSCs by training the network without giving it a short-termmemory, for this task.

  • 41.
    Khan, Zain Ahmed
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. Högskolan i Gävle.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Isaksson, Magnus
    Högskolan i Gävle.
    A Comparative Analysis of the Complexity/Accuracy Tradeoff in the Mitigation of RF MIMO Transmitter Impairments2017In: 89th ARFTG Microwave Measurement Conference: Advanced Technologies for Communications, ARFTG 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, article id 8000827Conference paper (Refereed)
    Abstract [en]

    This paper presents a comparative analysis of the complexity accuracy tradeoff in state-of-the-art RF MIMO transmitter mitigation models. The complexity and accuracy of the candidate models depends on the basis functions considered in these models. Therefore, a brief description of the mitigation models is presented accompanied by derivations of the model complexities in terms of the number of FLOPs. Consequently, the complexity accuracy tradeoff in the candidate models is evaluated for a 2 × 2 RF MIMO transmitter. Furthermore, the model complexities are analyzed for increasing nonlinear orders and number of antennas.

  • 42.
    Khan, Zain Ahmed
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. Universidad Catolica San Pablo, Peru.
    Zenteno, Efrain
    Dept. Electronics and Telecommunications, Universidad Catolica San Pablo, Arequipa, Peru.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Isaksson, Magnus
    Dept. Electronics, Mathematics, and Natural Sciences, University of Gävle, Gävle, Sweden.
    Multitone design for third order MIMO volterra kernels2017In: 2017 IEEE MTT-S International Microwave Symposium (IMS), Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 1553-1556, article id 8058925Conference paper (Refereed)
    Abstract [en]

    This paper proposes a technique for designing multitone signals that can separate the third order multiple input multiple output (MIMO) Volterra kernels. Multitone signals fed to a MIMO Volterra system yield a spectrum that is a permutation of the sums of the input signal tones. This a priori knowledge is used to design multitone signals such that the output from the MIMO Volterra kernels does not overlap in the frequency domain, hence making it possible to separate these kernels from the output of the MIMO Volterra system. The proposed technique is applied to a 2×2 RF MIMO transmitter to determine its dominant hardware impairments. For input crosstalk, the proposed method reveals the dominant self and cross kernels whereas for output crosstalk, the proposed method reveals that only the self kernels are dominant.

  • 43.
    Kizhakkumkara Muhamad, Raees
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Polar Codes for secure binary Wyner-Ziv source coding2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Source coding, originally envisaged by Claude Shannon in 1948 in his landmarkpaper "A Mathematical Theory of Communication" remained impractical forthe most part of the 20th century. However several advances were made incoding theory of which the latest-Polar Codes introduced by Erdal Arikan in2008 is highly promising. Polar Codes have modest encoding and decoding complexities,while providing a construction that directly leads to the fundamentalbounds obtained by Shannon. We are progressing further into the InformationAge, where high resolution videos are streamed over the Internet and variousdevices gather massive amounts of data while connected to each other in communicationnetworks. Hence the practical implication of an ecient and securesource coding scheme is signicant. In this thesis, we implement a source codingproblem called the Common helper in a Wyner-Ziv Network using polarcodes. Additionally the above construction leads to the lossy compression of aBernoulli Source and might provide an insight on how to develop ecient lossysource compression over a more general network.Source coding, originally envisaged by Claude Shannon in 1948 in his landmarkpaper "A Mathematical Theory of Communication" remained impractical forthe most part of the 20th century. However several advances were made incoding theory of which the latest-Polar Codes introduced by Erdal Arikan in2008 is highly promising. Polar Codes have modest encoding and decoding complexities,while providing a construction that directly leads to the fundamentalbounds obtained by Shannon. We are progressing further into the InformationAge, where high resolution videos are streamed over the Internet and variousdevices gather massive amounts of data while connected to each other in communicationnetworks. Hence the practical implication of an ecient and securesource coding scheme is signicant. In this thesis, we implement a source codingproblem called the Common helper in a Wyner-Ziv Network using polarcodes. Additionally the above construction leads to the lossy compression of aBernoulli Source and might provide an insight on how to develop ecient lossysource compression over a more general network.

  • 44. Kuyuk, R. T.
    et al.
    Celebi, Hasan Basri
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Hokelek, I.
    Oren, O.
    Yeni, A.
    Saribudak, A.
    Kara, F.
    Vicil, G.
    Uyar, M. u.
    An interoperability testbed for VoIP terminals2013Conference paper (Refereed)
    Abstract [en]

    We present an interoperability test automation system developed by TUBITAK BILGEM for Wireless Telecommunication Technologies Research Lab (KITAL) project under the sponsorship of Ministry of Development. This test system, called Shadow Coordinator, aims to verify the behavior of various wired and wireless terminals developed either at BILGEM or by industrial vendors as defined by SIP, SCIP and other related protocol specifications. Minimum-length and maximum coverage test sequences are generated using EFSM models and techniques defined in test theory. At the first stage of the project, interoperability of MILSEC-4 terminals is targeted.

  • 45.
    Larsson, Robin
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Skog, Isaac
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Inertial Sensor Driven Smartphone and Automobile Coordinate System Alignment2017In: 2017 IEEE 20TH INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    In this study a method is presented for estimating the orientation of an inertial measurement unit (IMU) located within an automobile, using only the measurements from the IMU itself. The orientation estimation problem is posed as a non-linear filtering probletn, which is solved using a marginalized particle filter. The performance of the proposed method is evaluated using a large collection of real-world data, collected by multiple drivers. The drivers used their own smartphones and had no restrictions on smartphone handling during drives. The orientation accuracy achieved with the proposed method is in the order of a few degrees; 50% of cases were below 5 degrees and 90% of cases were below 20 degrees.

  • 46. Li, J.
    et al.
    Sun, J.
    Qian, Y.
    Shu, F.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Xiang, W.
    A Commercial Video-Caching System for Small-Cell Cellular Networks Using Game Theory2016In: IEEE Access, E-ISSN 2169-3536, Vol. 4, p. 7519-7531, article id 7496825Article in journal (Refereed)
    Abstract [en]

    Evidence indicates that requesting video clips on demand accounts for a dramatic increase in data traffic over cellular networks. Caching part of popular videos in the storage of small-cell base stations (SBS) in cellular networks is an efficient method to reduce transmission latency and mitigate redundant transmissions. In this paper, we propose a commercial caching system consisting of a video retailer (VR) and multiple network service providers (NSPs). Each NSP leases its SBSs, with some price, to the VR for the purpose of making profits, and the VR, after storing popular videos in the rented SBSs, can provide better local video services to the mobile users, thereby gaining more profits. We conceive this system within the framework of a Stackelberg game by treating the SBSs as a specific type of resources. Then, we establish the profit models for both the NSPs and the VR based on stochastic geometry. We further investigate the Stackelberg equilibrium by solving the optimization problems in two cases, i.e., whether or not the VR has a budget plan on renting the SBSs. Numerical results are provided for quantifying the proposed framework by showing its efficiency on pricing and resource allocation.

  • 47.
    Li, Zuxing
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Privacy-by-Design for Cyber-Physical Systems2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    It is envisioned that future cyber-physical systems will provide a more convenient living and working environment. However, such systems need inevitably to collect and process privacy-sensitive information. That means the benefits come with potential privacy leakage risks. Nowadays, this privacy issue receives more attention as a legal requirement of the EU General Data Protection Regulation. In this thesis, privacy-by-design approaches are studied where privacy enhancement is realized through taking privacy into account in the physical layer design. This work focuses in particular on cyber-physical systems namely sensor networks and smart grids. Physical-layer performance and privacy leakage risk are assessed by hypothesis testing measures.

    First, a sensor network in the presence of an informed eavesdropper is considered. Extended from the traditional hypothesis testing problems, novel privacy-preserving distributed hypothesis testing problems are formulated. The optimality of deterministic likelihood-based test is discussed. It is shown that the optimality of deterministic likelihood-based test does not always hold for an intercepted remote decision maker and an optimal randomized decision strategy is completely characterized by the privacy-preserving condition. These characteristics are helpful to simplify the person-by-person optimization algorithms to design optimal privacy-preserving hypothesis testing networks.

    Smart meter privacy becomes a significant issue in the development of smart grid technology. An innovative scheme is to exploit renewable energy supplies or an energy storage at a consumer to manipulate meter readings from actual energy demands to enhance the privacy. Based on proposed asymptotic hypothesis testing measures of privacy leakage, it is shown that the optimal privacy-preserving performance can be characterized by a Kullback-Leibler divergence rate or a Chernoff information rate in the presence of renewable energy supplies. When an energy storage is used, its finite capacity introduces memory in the smart meter system. It is shown that the design of an optimal energy management policy can be cast to a belief state Markov decision process framework.

  • 48.
    Li, Zuxing
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Oechtering, Tobias
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Gunduz, Deniz
    Department of Electrical and Electronic Engineering, Imperial College London, United Kingdom.
    Smart Meter Privacy Based on Adversarial Hypothesis Testing2017In: Proceedings of the IEEE International Symposium on Information Theory (ISIT) 2017, IEEE, 2017, p. 774-778Conference paper (Refereed)
    Abstract [en]

    Privacy-preserving energy management is studied in the presence of a renewable energy source. It is assumed that the energy demand/supply from the energy provider is tracked by a smart meter. The resulting privacy leakage is measured through the probabilities of error in a binary hypothesis test, which tries to detect the consumer behavior based on the meter readings. An optimal privacy-preserving energy management policy maximizes the minimal Type II probability of error subject to a constraint on the Type I probability of error. When the privacy-preserving energy management policy is based on all the available information of energy demands, energy supplies, and hypothesis, the asymptotic exponential decay rate of the maximum minimal Type II probability of error is characterized by a divergence rate expression. Two special privacy-preserving energy management policies, the memoryless hypothesis-aware policy and the hypothesis-unaware policy with memory, are then considered and their performances are compared. Further, it is shown that the energy supply alphabet can be constrained to the energy demand alphabet without loss of optimality for the evaluation of a single-letter-divergence privacy-preserving guarantee.

  • 49.
    Lime, Hugo
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Cross-subframe channel estimation for low-complexity devices in LTE2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    One of the most critical issues of wireless communication systems is the timevaryingand frequency-selective channel. Knowledge about the channel greatlyimproves communication performance. It enables coherent demodulation andmeasurements of Signal to Noise Ratio (SNR) and Channel Quality Indicators(CQI). Theses measurements are used to optimize the transmission schemes dependingon the channel conditions. Therefore, the channel estimation is one ofthe most important feature of modern wireless communication devices. In the3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) system,estimation of the channel is achieved using pilots called Reference Signals (RSs)which are scattered in time and frequency. The full estimation of the channel isdone by filtering and interpolation of the estimated pilots.The 3GPP Release 13 issued in June 2016 defines a new category of UserEquipment (UE) named category M1 (Cat-M1) which should support low SNRscenarios. At such low SNR, legacy channel estimation techniques based on persubframeestimation are not efficient enough. The standard thus enables crosssubframechannel estimation by insuring persistence of the channel conditionsduring a group of subframes.This thesis presents techniques for cross-subframe channel estimation. It showshow algorithms can be devised to obtain improved estimation accuracy comparedto single-subframe channel estimates while being resistant to Doppler effect andclock frequency offset. Three types of algorithms are studied: linear averaging,first-order Infinite Impulse Response (IIR) filters and Finite Impulse Response(FIR) Wiener filters. An analytic study of these algorithms is performed to findoptimal parameters in terms of channel estimation Mean Square Error (MSE).Algorithm validation is done with computer simulations to show that the BitError Rate (BER) performance of low-complexity algorithms (linear averagingand first-order IIR filtering) are very close to optimal Wiener filtering ones andthat they provide significant improvement over single-subframe techniques.

  • 50.
    Liu, Du
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Flierl, Markus
    KTH, School of Electrical Engineering (EES), Sound and Image Processing (Closed 130101). KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Video coding using multi-reference motion-adaptive transforms based on graphs2016In: 2016 IEEE 12th Image, Video, and Multidimensional Signal Processing Workshop, IVMSP 2016, IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    The purpose of the work is to produce jointly coded frames for efficient video coding. We use motion-adaptive transforms in the temporal domain to generate the temporal subbands. The motion information is used to form graphs for transform construction. In our previous work, the motion-adaptive transform allows only one reference pixel to be the lowband coefficient. In this paper, we extend the motion-adaptive transform such that it permits multiple references and produces multiple lowband coefficients, which can be used in the case of bidirectional or multihypothesis motion estimation. The multi-reference motion-adaptive transform (MRMAT) is always orthonormal, thus, the energy is preserved by the transform. We compare MRMAT and the motion-compensated orthogonal transform (MCOT) [1], while HEVC intra coding is used to encode the temporal subbands. The experimental results show that MRMAT outperforms MCOT by about 0.6dB.

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