http://hdl.handle.net/10993/80 Search this channel search http://orbilu.uni.lu/simple-search http://hdl.handle.net/10993/41788 Title: Leveraging Privileged Information to Limit Distraction in End-to-End Lane Following <br/> <br/>Author, co-author: Robinet, François; Demeules, Antoine; Frank, Raphaël; Varisteas, Georgios; Hundt, Christian <br/> <br/>Abstract: Convolutional Neural Networks have been successfully used to steer vehicles using only road-facing cameras. In this work, we investigate the use of Privileged Information for training an end-to-end lane following model. Starting from the prior assumption that such a model should spend a sizeable fraction of its focus on lane markings, we take advantage of lane geometry information available at training time to improve its performance. To this end, we constrain the class of learnable functions by imposing a prior stemming from a lane segmentation task. For each input frame, we compute the set of pixels that most contribute to the prediction of the model using the VisualBackProp method. These pixel-relevance heatmaps are then compared with ground truth lane segmentation masks. A Distraction Loss term is added to the objective to regularize the training process. We learn from real-world data collected using our experimental vehicle and compare the results to those obtained using the simple Mean Squared Error objective. We show that the presence of our regularizer benefits both the performance and the stability of the model across a variety of evaluation metrics. We use a pretrained lane segmentation model without fine-tuning to extract lane marking masks and show that valuable learning signals can be extracted even from imperfect privileged knowledge. This method can be implemented easily and very efficiently on top of an existing architecture, without requiring the addition of any trainable parameter. http://hdl.handle.net/10993/41787 Title: Outer and Anti Joins in Temporal-Probabilistic Databases <br/> <br/>Author, co-author: Papaioannou, Katerina; Theobald, Martin; Böhlen, Michael H. http://hdl.handle.net/10993/41786 Title: Closed Form Discrete Unimodular MIMO Waveform Design Using Block Circulant Decomposition <br/> <br/>Author, co-author: Hammes, Christian; Shankar, Bhavani; Ottersten, Björn <br/> <br/>Abstract: This paper deals with the waveform design under the constraint of discrete multiphase unimodular sequences. It relies on Block Circulant decomposition of the slow-time transmitted waveform. The presented closed-form solution is capable of designing orthogonal signals, such that the virtual MIMO paradigm is enabled leading to enhanced angular resolution. On the other hand, the proposed method is also capable of approximating any desired radiation pattern within the physical limits of the transmitted array size. Simulation results prove the effectiveness in terms computational complexity, orthogonal signal design and the transmit beam pattern design under constant modulus constraint. http://hdl.handle.net/10993/41785 Title: Anytime Approximation in Probabilistic Databases via Scaled Dissociations <br/> <br/>Author, co-author: Van den Heuvel, Maarten; Ivanov, Peter; Gatterbauer, Wolfgang; Geerts, Floris; Theobald, Martin http://hdl.handle.net/10993/41783 Title: rom Big Data to Big Knowledge - Large-Scale Information Extraction Based on Statistical Methods (Invited Talk) <br/> <br/>Author, co-author: Theobald, Martin http://hdl.handle.net/10993/41782 Title: ACMiner: Extraction and Analysis of Authorization Checks inAndroid’s Middleware <br/> <br/>Author, co-author: Gorski III, Sigmund Albert; Andow, Benjamin; Nadkarni, Adwait; Manandhar, Sunil; Enck, William; Bodden, Eric; Bartel, Alexandre <br/> <br/>Abstract: Billions of users rely on the security of the Android platform to protect phones, tablets, and many different types of consumer electronics. While Android’s permission model is well studied, the enforcementof the protection policy has received relatively little attention. Much of this enforcement is spread across system services,taking the form of hard-coded checks within their implementations.In this paper, we propose Authorization Check Miner (ACMiner),a framework for evaluating the correctness of Android’s access control enforcement through consistency analysis of authorization checks. ACMiner combines program and text analysis techniques to generate a rich set of authorization checks, mines the corresponding protection policy for each service entry point, and uses association rule mining at a service granularity to identify inconsistencies that may correspond to vulnerabilities. We used ACMiner to study the AOSP version of Android 7.1.1 to identify 28 vulnerabilities relating to missing authorization checks. In doing so, we demonstrate ACMiner’s ability to help domain experts process thousands of authorization checks scattered across millions of lines of code. http://hdl.handle.net/10993/41779 Title: A Multi-Hop Broadcast Wave Approach for Floating Car Data Collection in Vehicular Networks <br/> <br/>Author, co-author: Turcanu, Ion; Salvo, Pierpaolo; Baiocchi, Andrea; Cuomo, Francesca; Engel, Thomas <br/> <br/>Abstract: Inter-Vehicle Communication (IVC) is bringing connected and cooperative mobility closer to reality. Vehicles today are able to produce huge amounts of information, known in the literature as Floating Car Data (FCD), containing status information gathered from sensing the internal condition of the vehicle and the external environment. Adding networking capabilities to vehicles allows them to share this information among themselves and with the infrastructure. Collecting real-time FCD information from vehicles opens up the possibility of having access to an enormous amount of useful information that can boost the development of innovative services and applications in the domain of Intelligent Transportation System (ITS). In this paper we propose several solutions to efficiently collect real-time FCD information in Dedicated Short-Range Communication (DSRC)-enabled Vehicular Ad Hoc Networks (VANETs). The goal is to improve the efficiency of the FCD collection operation while keeping the impact on the DSRC communication channel as low as possible. We do this by exploiting a slightly modified version of a standardized data dissemination protocol to create a backbone of relaying vehicles that, by following local rules, generate a multi-hop broadcast wave of collected FCD messages. The proposed protocols are evaluated via realistic simulations under different vehicular densities and urban scenarios. http://hdl.handle.net/10993/41778 Title: Non-Intrusive Cognitive Measurement for the Amplitude Response of Wideband Transponders <br/> <br/>Author, co-author: Mazalli, N.; Andrenacci, Stefano; Chatzinotas, Symeon <br/> <br/>Abstract: In this paper we propose a new measurement procedure for the amplitude response of a wideband transponder in an in-orbit testing (IOT) context. The proposed procedure resorts to a direct sequence spread spectrum (DSSS) technique in order to limit the interference caused by the measurement signals to the traffic. Further, an adaptive approach exploiting the knowledge of the inband traffic power has been introduced. Such knowledge, acquired either a priori or by sensing the channel, allows to easily design measurement signals satisfying multiple performance requirements (i.e., accuracy, resolution, interference, duration, and complexity). The proposed procedure can be used as a design tool to optimize the dimensioning of the IOT system parameters, and to flexibly trade off a performance indicator against another. http://hdl.handle.net/10993/41777 Title: Editorial on energy-aware future-networked smart cities <br/> <br/>Author, co-author: Jayakody, N.; Imran, M.A.; Chatzinotas, Symeon; Hassan, S.A. http://hdl.handle.net/10993/41776 Title: RLS Waveform Adaptation for Massive MIMO Systems with Nonlinear Front-End <br/> <br/>Author, co-author: Bereyhi, A.; Asaad, S.; Müller, R.R; Chatzinotas, Symeon <br/> <br/>Abstract: To keep massive MIMO systems cost-efficient, power amplifiers with rather small output dynamic ranges are employed. They may distort the transmit signal and degrade the performance. This paper proposes a distortion aware precoding scheme for realistic scenarios in which RF chains have nonlinear characteristics. The proposed scheme utilizes the method of regularized least-squares (RLS) to jointly compensate the channel impacts and the distortion imposed by the RF chains. To construct the designed transmit waveform with low computational complexity, an iterative algorithm based on approximate message passing is developed. This algorithm is shown to track the achievable average signal distortion of the proposed scheme tightly, even for practical system dimensions. The results demonstrate considerable enhancement compared to the state of the art. Index Terms-Precoding, nonlinear power amplifiers, approximate message passing, regularized least-squares, massive MIMO. http://hdl.handle.net/10993/41772 Title: Robust Precoding Techniques for Multibeam Mobile Satellite Systems <br/> <br/>Author, co-author: Joroughi, Vahid; Shankar, Bhavani; Maleki, Sina; Chatzinotas, Symeon; Grotz, Joel; Ottersten, Björn <br/> <br/>Abstract: This paper presents designing precoding technique at the gateway of a multibeam mobile satellite systems, enabling full frequency reuse pattern among the beams. Such a system brings in two critical challenges to overcome. The inter-beam interference makes applying interference mitigation techniques necessary. Further, when the user terminals are mobile the Channel State Information (CSI) becomes time-varying which is another challenge to overcome. Therefore, the gateway has only access to an outdated CSI, which can eventually limit the precoding gains. In this way, employing a proper CSI estimation mechanism at the gateway can improve the performance of the precoding scheme. In this context, the objectives of this paper are two folds. First, we present different CSI feedback mechanisms which aim at preserving a lower CSI variations at the gateway. Then, we develop the corresponding precoding schemes which are adapted with the proposed CSI feedback mechanisms. To keep the complexity of the proposed precoding schemes affordable, we consider a maritime communication scenario so that the signals received by mobile user terminals suffer from a lower pathloss compared to the Land Mobile communication. Finally, we provide several simulations results in order to evaluate the performance of the proposed precoding techniques. http://hdl.handle.net/10993/41771 Title: Outage Performance of Integrated Satellite-Terrestrial Relay Networks with Opportunistic Scheduling <br/> <br/>Author, co-author: Huang, Qingquan; Zhu, Wei-Ping; Chatzinotas, Symeon; Alouini, Mohamed-Slim Alouini <br/> <br/>Abstract: In this paper, we investigate the outage performance of a multiuser threshold-based decode-and-forward integrated satellite-terrestrial relay network (ISTRN) with opportunistic user scheduling, where the satellite link and terrestrial links undergo Shadowed-Rician (SR) fading and correlated Rayleigh fading, respectively. First, we propose a new probability density function (PDF) to statistically characterize the square sum of independent and identically distributed SR random variables, which is more accurate and concise than existing expressions. Next, based on the new PDF, we derive an analytical expression of outage probability (OP) of the considered network. Furthermore, the asymptotic OP expression is developed at high signal-to-noise ratio to reveal the achievable diversity order of the considered ISTRN. Finally, computer simulation is conducted to validate the analytical results, and show the impact of various parameters on the outage performance. http://hdl.handle.net/10993/41770 Title: On the Performance of the Uplink Satellite Multiterrestrial Relay Networks With Hardware Impairments and Interference <br/> <br/>Author, co-author: Guo, Kefeng; An, Kang; Zhang; Huang, Yuzhen; Guo, Daoxing; Zheng, Gan; Chatzinotas, Symeon <br/> <br/>Abstract: In this paper, we consider an uplink satellite multiterrestrial relay network, which employs a single-antenna user to communicate with a satellite via multiple decode-and-forward (DF) terrestrial relays. Due to the spectrum sharing policy, terrestrial relays are interfered by cochannel interference (CCI). For inevitable radio frequency (RF) front-end imperfections, the interconnected nodes of the whole network are always impaired by inherent hardware impairments (HIs). Specifically, in order to improve the overall system performance, a partial relay selection scheme is used to enhance the system performance by improving the spatial diversity. On this foundation, we have derived the closed-form expressions for the outage probability (OP) and throughput of the considered system, where both the satellite and terrestrial channels are under independent nonidentical distributions. To get better insights at high signal-to-noise-ratios (SNRs), the asymptotic behaviors for the system performance are also derived. From the asymptotic results, the impacts of CCI and the HIs on the system performance are quantitatively analyzed. Especially, the OP and throughput will have bounds when the system is under HIs. Monte Carlo (MC) simulation results corroborate the theoretical analysis and illustrate the joint effects of CCI and HIs on the considered system. http://hdl.handle.net/10993/41769 Title: The Application of Power-Domain Non-Orthogonal Multiple Access in Satellite Communication Networks <br/> <br/>Author, co-author: Yan, Xiaojuan; An, Kang; Liang, Tao; Zheng, Gan; Ding, Zhiguo; Chatzinotas, Symeon; Liu, Yan <br/> <br/>Abstract: Satellite communication networks are expected to be indispensable as part of an integrated complement for the upcoming 5G networks since they can provide the most comprehensive coverage and reliable connection for areas where are economically unviable and/or difficult to deploy terrestrial infrastructures. Meanwhile, the power-domain non-orthogonal multiple access (NOMA), which can serve multiple users simultaneously within the same time/frequency block, has been viewed as another promising strategy used in the 5G network to provide high spectral efficiency and resource utilization. In this paper, we introduce a general overview of the application of the NOMA to various satellite architectures for the benefits of meeting the availability, coverage, and efficiency requirements targeted by the 5G. The fundamental and ubiquitous features of satellite link budget are first reviewed. Then, the advantage and benefit of introducing the NOMA scheme in various satellite architectures, such as conventional downlink/uplink satellite networks, cognitive satellite terrestrial networks, and cooperative satellite networks with satellite/terrestrial relays, are provided, along with the motivation and research methodology for each scenario. Finally, this paper reviews the potential directions for future research. http://hdl.handle.net/10993/41768 Title: Dynamic RF Chain Selection for Energy Efficient and Low Complexity Hybrid Beamforming in Millimeter Wave MIMO Systems <br/> <br/>Author, co-author: Kaushik, Aryan; Thompson, John; Vlachos, Evangelos; Tsinos, Christos; Chatzinotas, Symeon <br/> <br/>Abstract: This paper proposes a novel architecture with a framework that dynamically activates the optimal number of radio frequency (RF) chains used to implement hybrid beamforming in a millimeter wave (mmWave) multiple-input and multiple-output (MIMO) system. We use fractional programming to solve an energy efficiency maximization problem and exploit the Dinkelbach method (DM)-based framework to optimize the number of active RF chains and data streams. This solution is updated dynamically based on the current channel conditions, where the analog/digital (A/D) hybrid precoder and combiner matrices at the transmitter and the receiver, respectively, are designed using a codebook-based fast approximation solution called gradient pursuit (GP). The GP algorithm shows less run time and complexity while compared to the state-of-the-art orthogonal matching pursuit (OMP) solution. The energy and spectral efficiency performance of the proposed framework is compared with the existing state-of-the-art solutions, such as the brute force (BF), the digital beamformer, and the analog beamformer. The codebook-free approaches to design the precoders and combiners, such as alternating direction method of multipliers (ADMMs) and singular value decomposition (SVD)-based solution are also shown to be incorporated into the proposed framework to achieve better energy efficiency performance. http://hdl.handle.net/10993/41754 Title: Performance Analysis of Integrated Satellite-Terrestrial Multiantenna Relay Networks with Multiuser Scheduling <br/> <br/>Author, co-author: Huang, Qingquan; Lin, Min; Zhu, Wei-Ping; Chatzinotas, Symeon; Alouini, Mohamed-Slim <br/> <br/>Abstract: In this paper, we investigate the performance of a multiuser integrated satellite-terrestrial relay network (ISTRN) with threshold-based decode-and-forward protocol, where the satellite-relay link undergoes Shadowed-Rician (SR) fading while the relay-user links experience Nakagami-m fading. We first formulate a constrained optimization problem with an objective to maximize the system capacity in order to determine the beamforming weight vectors at the relay, and thereby develop two multiuser scheduling schemes, namely, best user scheduling and user fairness scheduling. Then, we present a closedform expression for the probability density function (PDF) of the square sum of independent and identically distributed SR random variables, which is more accurate and concise than the existing solutions. Based on the new PDF results, we derive closedform expressions for the outage probability (OP) and ergodic capacity of the considered network using the two scheduling schemes. Furthermore, the asymptotic OP expressions at high signal-to-noise ratio are also deduced to reveal the asymptotic behavior of the considered ISTRN. Finally, simulation results are provided to validate our theoretical analysis, and show the impact of various parameters on the system performance. http://hdl.handle.net/10993/41749 Title: Non-localised contact between beams with circular and elliptical cross-sections <br/> <br/>Author, co-author: Magliulo, Marco; Lengiewicz, Jakub; Zilian, Andreas; Beex, Lars <br/> <br/>Abstract: The key novelty of this contribution is a dedicated technique to e fficiently determine the distance (gap) function between parallel or almost parallel beams with circular and elliptical cross-sections. The technique consists of parametrizing the surfaces of the two beams in contact, fixing a point on the centroid line of one of the beams and searching for a constrained minimum distance between the surfaces (two variants are investigated). The resulting unilateral (frictionless) contact condition is then enforced with the Penalty method, which introduces compliance to the, otherwise rigid, beams' cross-sections. Two contact integration schemes are considered: the conventional slave-master approach (which is biased as the contact virtual work is only integrated over the slave surface) and the so-called two-half-pass approach (which is unbiased as the contact virtual work is integrated over the two contacting surfaces). Details of the finite element formulation which is suitably implemented using Automatic Di fferentiation techniques are presented. A set of numerical experiments shows the overall performance of the framework and allows a quantitative comparison of the investigated variants. http://hdl.handle.net/10993/41741 Title: Optimal Operation of Nearly Zero Energy Buildings using Mixed Integer Linear Programming <br/> <br/>Author, co-author: Rafii-Tabrizi, Sasan; Hadji-Minaglou, Jean-Régis; Scholzen, Frank; Capitanescu, Florin <br/> <br/>Abstract: This paper proposes a deterministic mixed integer linear programming model for the optimal operation of an energy system providing thermal and electrical energy for a residential and commercial nearly zero energy building. The space heating and space cooling demand of the buildings is simulated using a resistive-capacitive model within a quadratic program respectively. Thermal energy for space heating, space cooling and domestic hot water is buffered in thermal energy storage systems. A dual source heat pump provides thermal energy for space heating and domestic hot water, whereas space cooling is covered by an underground ice storage. The environmental energy sources of the heat pump are ice storage or wind infrared sensitive collectors. The collectors are further used to regenerate the ice storage. Further space heating demands are covered by a combined heat and power unit, which also produces electricity. Photovoltaic panels produce electrical energy which can be stored in a battery storage system. The electrical energy system is capable of selling and buying electricity from the public power grid. A mixed integer linear programming model is developed to minimise the operation cost of the combined commercial and residential nearly zero energy building over a scheduling horizon of 24h. The developed model is tested on two typical days, which are representative for the summer and winter season. Furthermore, it is investigated how external incentives such as varying electricity prices impact the optimal scheduling of the energy system. http://hdl.handle.net/10993/41739 Title: Mixed Integer Linear Programming Model for the Optimal Operation of a Dual Source Heat Pump <br/> <br/>Author, co-author: Rafii-Tabrizi, Sasan; Hadji-Minaglou, Jean-Régis; Scholzen, Frank <br/> <br/>Abstract: This paper presents a mixed integer linear programming (MILP) model to optimally operate a dual source heat pump (DSHP). The DSHP draws environmental energy from an underground ice storage tank (IST) or wind infrared sensitive collectors (WISC). WISC is further used to regenerate the IST. The thermal output of the DSHP is stored in a thermal energy storage (TES). A single-objective optimization approach is applied to minimize the operational cost of the DSHP over a scheduling horizon of 24h. The developed framework is tested on various days, which are representative for each season of the year. Furthermore, it is investigated how variable electricity price market data influence the dynamic behaviour of the DSHP. http://hdl.handle.net/10993/41735 Title: Towards Dynamic Zero Emission Zone Management for Plug-in Hybrid Buses <br/> <br/>Author, co-author: Seredynski, Marcin; Viti, Francesco