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  • 301.
    Parsapoor, Mahboobeh
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Towards Emotion inspired Computational Intelligence (EiCI)2015Doctoral thesis, monograph (Other academic)
    Abstract [en]

    One of the main challenges in the computational intelligence (CI) community is to develop nature-inspired algorithms that can efficiently solve real-world problems such as the prediction of space weather phenomena. An early example in this context is taking inspiration from the biological neurons in the mammal’s nervous system and developing an artificial neuron. This work laid the foundation for artificial neural networks (ANNs) that aim to mimic the connections between neurons in the mammal’s nervous system and to develop an artificial model of the brain. ANNs are well-known CI models that have shown high generalization capability when solving real-world problems, e.g., chaotic time-series prediction problems. However, ANNs mostly tend to suffer from long computation time and high model complexity. This thesis presents a new category of CI paradigms by taking inspiration from emotions, and these CI models are referred to as emotion-inspired computational intelligence models (EiCIs). In the thesis, I have outlined the preliminary steps that have been taken to develop EiCIs. These steps include studying different emotional theories and hypotheses, designing and implementing CI models for two specific applications in artificial intelligence (prediction and optimization), evaluating the performance of the new CI models, and comparing the obtained results with the results of well-known CI models (e.g., ANNs) and discussing the potential improvement that can be achieved. The first step, and a significant contribution of this thesis, is to review the various definitions of emotions and to investigate which emotional theories that are the most relevant for developing a CI model. Amongst different theories and hypotheses of emotions, the fear conditioning hypothesis as well as affect theory have been two main sources of inspiration in the development of the EiCIs proposed in this thesis. The fear conditioning hypothesis that was first proposed by LeDoux reveals some important characteristics of the underlying neural structure of fear conditioning behavior in biological systems. Based on the features of such networks, it could be an applicable hypothesis to be the basis of the development of a subgroup of EiCIs that could be used for prediction applications, e.g. BELIMs (Brain Emotional Learning Inspired Models), and as emotion-inspired engines for decision-making applications.The second emotional theory of the thesis is the affect theory (which was first suggested by Silvan Tomkins) that describes what the basic emotions are and how they can be associated with facial expressions. A mechanism to express the basic emotional feelings is also useful in designing another category of EiCIs that are referred to as emotion-inspired optimization methods. The fundamental hypotheses of the thesis, have led to developing EiCIs, can be presented as follows. The first hypothesis is that the neural structure of fear conditioning can be considered to be a nature-based system with the capability to show intelligent behavior through its functionality. This hypothesis is stated on the basis of the three main characteristics of the neural structure of fear conditioning behavior.The first characteristic is that the amygdala is the main center for processing fear-induced stimuli and that it provides the fear reaction through its interaction with other regions of the brain such as the sensory cortex, the thalamus, and the hippocampus. The second characteristic is that the procedure of processing of fearful stimuli and the provision of emotional reactions is simple and quick. The third aspect is that the amygdala not only provides fear responses but also learns to predict aversive events by interacting with other regions of the brain, which means that an intelligent behavior emerges.The second hypothesis is that the system in which the three monoamines neurotransmitters serotonin, dopamine, and noradrenalin and thus produces emotional behaviors, can be viewed as a biological system associated with the emergence of intelligent behavior.The above hypotheses state that a suitable way to develop new CI models is to take inspiration from the neural structure of fear conditioning and the natural system of three monoamine neurotransmitters. A significant contribution of this thesis is the evaluation of the ability of EiCIs by examining them to solve real-world problems such as the prediction of space weather phenomena (e.g., predicting real time-series such as sunspot number, auroral electrojet index, and disturbance time index) and the optimization of some central procedures in network communications. These evaluations have led to that comparable results have been obtained, which in turn supports the conclusion that EiCIs have acceptable and reasonable performance regarding computation time and model complexity. However, to achieve the final goal of the research study (i.e., to develop a CI model with low computation time and low model complexity), some enhancements of EiCIs are necessary. Moreover, new designs and implementations of these models can be developed by taking inspiration from other theories.

  • 302.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    A Centralized Channel Assignment Algorithm for Clustered Ad Hoc Networks2013In: ICWiSe: Sarawak : 2 – 4 December 2013: Proceeding Book / [ed] Hamzah Asyrani Bin Sulaiman, Mohd Azlishah Bin Othman & Muhammad Noorazlan Shah Bin Zainudin, Piscataway, NJ: IEEE conference proceedings, 2013, , p. 6p. 73-78, article id 6728784Conference paper (Refereed)
    Abstract [en]

    This paper presents new channel assignment algorithm for a clustered ad hoc network. The suggested method is based on a graph-theoretic model and seeks a solution for the channel assignment problem in a clustered ad hoc network. The method is based on a new meta-heuristic algorithm that is referred to as imperialist competitive algorithm (ICA). It provides a scheme for allocating the available channels to the cluster heads, maximizing spectrum efficiency and minimizing co-channel interference. The suggested method is tested for several scenarios and its performance is compared with a genetic algorithm based scheme. © 2013 IEEE

  • 303.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    An emotional learning-inspired ensemble classifier (ELiEC)2013In: Proceedings of the 2013 Federated Conference on Computer Science and Information Systems (FedCSIS) / [ed] M. Ganzha, L. Maciaszek & M. Paprzycki, Los Alamitos, CA: IEEE Computer Society, 2013, p. 137-141, article id 6643988Conference paper (Refereed)
    Abstract [en]

    In this paper, we suggest an inspired architecture by brain emotional processing for classification applications. The architecture is a type of ensemble classifier and is referred to as 'emotional learning-inspired ensemble classifier' (ELiEC). In this paper, we suggest the weighted k-nearest neighbor classifier as the basic classifier of ELiEC. We evaluate the ELiEC's performance by classifying some benchmark datasets. © 2013 Polish Information Processing Society.

  • 304.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    An Imperialist Competitive Algorithm For Interference-Aware Cluster-heads Selection in Ad hoc Networks2014In: Proceedings: 2014 IEEE 28th International Conference on Advanced Information Networking and Applications: IEEE AINA 2014: 13-16 May 2014: University of Victoria, Victoria, Canada, Los Alamitos, CA: IEEE Computer Society, 2014, p. 41-48Conference paper (Other academic)
    Abstract [en]

    This paper presents the results of applying a new clustering algorithm in ad hoc networks. This algorithm is a centralized method and is designed on the basis of an imperialist competitive algorithm (ICA). This algorithm aims to find a minimum number of cluster-heads while satisfying two constraints, the connectivity and interference. This work is a part of an ongoing research to develop a distributed interference aware cluster-based channel allocation method. As a matter of fact, the results of the centralized method are required to provide an upper level for the performance of the distributed version. The suggested method is evaluated for several scenarios and compares the obtained results with the reported results of ant colony optimization-based methods. © 2014 IEEE.

  • 305.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Ant Colony Optimization for Channel Assignment Problem in Clustered Mobile Ad Hoc Network2013In: Advances in Swarm Intelligence, Berlin Heidelberg: Springer Berlin/Heidelberg, 2013, Vol. 7928, p. 314-322Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    This paper presents an ant colony optimization (ACO) method as a method for channel assignment in a mobile ad hoc network (MANET), where achieving high spectral efficiency necessitates an efficient channel assignment. The suggested algorithm is intended for graph-coloring problems and it is specifically tweaked to the channel assignment problem in MANET with a clustered network topology. A multi-objective function is designed to make a tradeoff between maximizing spectral utilization and minimizing interference. We compare the convergence behavior and performance of ACO-based method with obtained results from a grouping genetic algorithm (GGA). © 2013 Springer-Verlag Berlin Heidelberg.

  • 306.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Brain Emotional Learning Based Fuzzy Inference System (BELFIS) for Solar Activity Forecasting2012In: 2012 IEEE 24th International Conference on Tools with Artificial Intelligence (ICTAI 2012), Vol. 1, Piscataway, NJ: IEEE Press, 2012, p. 532-539, article id 6495090Conference paper (Refereed)
    Abstract [en]

    This paper presents a new architecture based on a brain emotional learning model that can be us.ed in a wide varieties of AI applications such as prediction, identification and classification. The architecture is referred to as: Brain Emotional Learning Based Fuzzy Inference System (BELFIS) and it is developed from merging the idea of prior emotional models with fuzzy inference systems. The main aim of this model is presenting a desirable learning model for chaotic system prediction imitating the brain emotional network. In this research work, the model is used for predicting the solar activity, since it has been recognized as a threat to critical infrastructures in modern society. Specifically sunspot numbers are predicted by applying the proposed brain emotional learning model. The prediction results are compared with the outcomes of using other previous models like the locally linear model tree (LOLIMOT) and radial bias function (RBF) and adaptive neuro-fuzzy inference system (ANFIS). © 2012 IEEE.

  • 307.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Emotional Learning Inspired Engine: for Cognitive Radio Networks2014Conference paper (Other academic)
    Abstract [en]

    This paper suggests a new engine to be used to develop cognitive nodes in cognitive radio networks. Instead of the traditional cognitive cycle, the suggested engine could be designed based on an emotional cycle that is inspired by the emotional system that reacts to the received stimulus and learns from the reaction. The engine is called ELIE that stands for Emotional Learning Inspired Engine. This paper presents the structure of ELIE and explains how it can be implemented on the basis of generic policy architecture. This paper also discusses the possible applications of the suggested engine.

  • 308.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Imperialist Competition Algorithm for DSA in Cognitive Radio Networks2012In: 2012 8th International Conference on Wireless Communications, Networking and Mobile Computing (WICOM2012): September 21-23, 2012, Shanghai, China / [ed] C. Kurzawa, D. Graffox & G. MacPherson, Piscataway, NJ: IEEE conference proceedings, 2012, p. 1726-1729, article id 6478538Conference paper (Refereed)
    Abstract [en]

    In this paper a novel optimization method called imperialist competitive algorithm (ICA) is applied to solve the channel assignment problem in a mobile ad hoc network. First the imperialist competitive algorithm (ICA) is described, which has been proposed as an evolutionary optimization method, and after that it is explained how it can seek a near optimal solution for the channel allocation problem in a cognitive mobile ad hoc radio network. The simulation results are compared with the results that were obtained by applying island genetic algorithm. © 2012 IEEE

  • 309.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Neuro-Fuzzy Models, BELRFS and LOLIMOT, for Prediction of Chaotic Time Series2012In: INISTA 2012: International Symposium on Innovations in Intelligent Systems and Applications : 2-4 July, 2012 : Trabzon, Turkey, Piscataway, N.J.: IEEE Press, 2012, p. Article number 6247025-, article id 624702Conference paper (Refereed)
    Abstract [en]

    This paper suggests a novel learning model for prediction of chaotic time series, brain emotional learning-based recurrent fuzzy system (BELRFS). The prediction model is inspired by the emotional learning system of the mammal brain. BELRFS is applied for predicting Lorenz and Ikeda time series and the results are compared with the results from a prediction model based on local linear neuro-fuzzy models with linear model tree algorithm (LoLiMoT). © 2012 IEEE.

  • 310.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Using the grouping genetic algorithm (GGA) for channel assignment in a cluster-based mobile ad hoc network2012In: Proceedings of SNCNW 2012: The 8th Swedish National Computer Networking Workshop: Stockholm, June 7-8, 2012, 2012, p. 56-60Conference paper (Refereed)
    Abstract [en]

    Next generation tactical military network will be based on mobile ad hoc networks (MANET). These networks require efficient spatial channel reuse in order to provide high spectral efficiency and this is only achieved by efficient channel assignment optimization. For a clustered network topology the basic goal is to assign different channels to adjacent clusters, i.e. a graph coloring problem. Unfortunately, is the optimal solution for graph coloring problems intractable, the problem is NP-hard. As a consequence heuristic methods must be applied, which provide solutions with as close to optimal result as possible. In this article the grouping genetic algorithm is applied for solving the channel assignment problem in a cluster based mobile ad hoc network. The used multi objective function minimizes interference and maximizes the spectral efficiency.

  • 311.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). School of Computer Science, Faculty of Engineering & Physical Science, The University of Manchester, Manchester, United Kingdom.
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Svensson, Bertil
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    A Brain Emotional Learning-based Prediction Model for the Prediction of Geomagnetic Storms2014In: Proceedings of the 2014 Federated Conference on Computer Science and Information Systems, Los Alamitos, CA: IEEE Press, 2014, p. 35-42Conference paper (Refereed)
    Abstract [en]

    This paper introduces a new type of brain emotional learning inspired models (BELIMs). The suggested model is  utilized as a suitable model for predicting geomagnetic storms. The model is known as BELPM which is an acronym for Brain Emotional Learning-based Prediction Model. The structure of the suggested model consists of four main parts and mimics the corresponding regions of the neural structure underlying fear conditioning. The functions of these parts are implemented by assigning adaptive networks to the different parts. The learning algorithm of BELPM is based on the steepest descent (SD) and the least square estimator (LSE). In this paper, BELPM is employed to predict geomagnetic storms using the Disturbance Storm Time (Dst) index. To evaluate the performance of BELPM, the obtained results have been compared with the results of the adaptive neuro-fuzzy inference system (ANFIS). © 2014 Polish Information Processing Society.

  • 312.
    Parsapoor, Mahboobeh
    et al.
    McGill University, Montreal, QC H3A 2T6, Canada.
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Svensson, Bertil
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Forecasting Solar Activity with Computational Intelligence Models2018In: IEEE Access, E-ISSN 2169-3536, Vol. 6, p. 70902-70909Article in journal (Refereed)
    Abstract [en]

    It is vital to accurately predict solar activity, in order to decrease the plausible damage of electronic equipment in the event of a large high-intensity solar eruption. Recently, we have proposed brain emotional learning-based fuzzy inference system (BELFIS) as a tool for the forecasting of chaotic systems. The structure of BELFIS is designed based on the neural structure of fear conditioning. The function of BELFIS is implemented by assigning adaptive networks to the components of the BELFIS structure. This paper especially focuses on the performance evaluation of BELFIS as a predictor by forecasting solar cycles 16-24. The performance of BELFIS is compared with other computational models used for this purpose, in particular with the adaptive neuro-fuzzy inference system. © 2018 IEEE.

  • 313.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). School of Computer Science, Faculty of Engineering & Physical Science, The University of Manchester, Manchester, United Kingdom.
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Svensson, Bertil
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Neuro-fuzzy Models for Geomagnetic Storms Prediction: Using the Auroral Electrojet Index2014In: 2014 10th International Conference on Natural Computation (ICNC), Piscataway, NJ: IEEE Press, 2014, p. 12-17, article id 6975802Conference paper (Refereed)
    Abstract [en]

    This study presents comparative results obtained from employing four different neuro-fuzzy models to predict geomagnetic storms. Two of these neuro-fuzzy models can be classified as Brain Emotional Learning Inspired Models (BELIMs). These two models are BELFIS (Brain Emotional Learning Based Fuzzy Inference System) and BELRFS (Brain Emotional Learning Recurrent Fuzzy System). The two other models are Adaptive Neuro-Fuzzy Inference System (ANFIS) and Locally Linear Model Tree (LoLiMoT) learning algorithm, two powerful neuro-fuzzy models to accurately predict a nonlinear system. These models are compared for their ability to predict geomagnetic storms using the AE index.

  • 314.
    Parsapoor, Mahboobeh
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). School of Computer Science, Faculty of Engineering & Physic al Science, The University of Manchester, Manchester, United Kingdom.
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Svensson, Bertil
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Prediction of Solar Cycle 24: Using a Connectionist Model of the Emotional System2015In: 2015 International Joint Conference on Neural Networks (IJCNN), Piscataway, NJ: IEEE Press, 2015, article id 7280839Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    Accurate prediction of solar activity as one aspect of space weather phenomena is essential to decrease the damage from these activities on the ground based communication, power grids, etc. Recently, the connectionist models of the brain such as neural networks and neuro-fuzzy methods have been proposed to forecast space weather phenomena; however, they have not been able to predict solar activity accurately. That has been a motivation for the development of the connectionist model of the brain; this paper aims to apply a connectionist model of the brain to accurately forecasting solar activity, in particular, solar cycle 24. The neuro-fuzzy method has been referred to as the brain emotional learning-based recurrent fuzzy system (BELRFS). BELRFS is tested for prediction of solar cycle 24, and the obtained results are compared with well-known neuro-fuzzy methods and neural networks as well as with physical-based methods. @2015 IEEE

  • 315.
    Paula, Maicke C. G.
    et al.
    University of Beira Interior, Covilhã, Portugal & Fiat Automobile, Brazil.
    Rodrigues, Joel J. P. C.
    University of Beira Interior, Covilhã, Portugal & ITMO University, St. Petersburg, Russia.
    Dias, João A.
    University of Beira Interior, Covilhã, Portugal.
    Isento, João N.
    University of Beira Interior, Covilhã, Portugal.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Performance Evaluation of a Real Vehicular Delay-Tolerant Network Testbed2015In: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477, Vol. 2015, article id 219641Article in journal (Refereed)
    Abstract [en]

    Vehicular Delay-Tolerant Networks (VDTNs) are a breakthrough based DTN solution used to provide vehicular communications under challenging scenarios, characterized by long delays and sporadic connections. Using the store-carry-and-forward paradigm, this technology allows in-transit bundles to asynchronously reach the destination hop by hop over traveling vehicles equipped with short-range wireless devices. The VDTN architecture assumes out-of-band signaling with control and data planes separation and follows an IP over VDTN approach. This paper presents a real-world VDTN prototype evaluated through a safety application and a Traffic Jam Information Service. It also demonstrates the real deployment of this new vehicular communication approach. The real testbed is an important contribution since some complex issues presented in vehicular communication systems can be studied more accurately in real-world environments than in a laboratory approach. The results confirm that real deployment of VDTNs is doable and can be seen as a very promising technology for vehicular communications, although it requires appropriated technologies for outline interferences and quality of service support. © 2015 Maicke C. G. Paula et al.

  • 316.
    Persson, Andreas
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bengtsson, Lars
    Department of Computer Science and Engineering, Chalmers University of Technology, Gothenburg, Sweden.
    Forward and Reverse Converters and Moduli Set Selection in Signed-Digit Residue Number Systems2009In: Journal of Signal Processing Systems, ISSN 1939-8018, E-ISSN 1939-8115, Vol. 56, no 1, p. 1-15Article in journal (Refereed)
    Abstract [en]

    This paper presents an investigation into using a combination of two alternative digital number representations; the residue number system (RNS) and the signed-digit (SD) number representation in digital arithmetic circuits. The combined number system is called RNS/SD for short. Since the performance of RNS/SD arithmetic circuits depends on the choice of the moduli set (a set of pairwise prime numbers), the purpose of this work is to compare RNS/SD number systems based on different sets. Five specific moduli sets of different lengths are selected. Moduli-set-specific forward and reverse RNS/SD converters are introduced for each of these sets. A generic conversion technique for moduli sets consisting of any number of elements is also presented. Finite impulse response (FIR) filters are used as reference designs in order to evaluate the performance of RNS/SD processing. The designs are evaluated with respect to delay and circuit area in a commercial 0.13 μm CMOS process. For the case of FIR filters it is shown that generic moduli sets with five or six moduli results in designs with the best area × delay products.

  • 317.
    Pignaton de Freitas, Edison
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Cooperative Context-Aware Setup and Performance of Surveillance Missions Using Static and Mobile Wireless Sensor Networks2011Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Surveillance systems are usually employed to monitor wide areas in which their usersaim to detect and/or observe events or phenomena of their interest. The use ofwireless sensor networks in such systems is of particular interest as these networks can provide a relative low cost and robust solution to cover large areas. Emerging applications in this context are proposing the use of wireless sensor networks composed of both static and mobile sensor nodes. Motivation for this trend is toreduce deployment and operating costs, besides providing enhanced functionalities.The usage of both static and mobile sensor nodes can reduce the overall systemcosts, by making low-cost simple static sensors cooperate with more expensive andpowerful mobile ones. Mobile wireless sensor networks are also desired in somespecific scenarios in which mobility of sensor nodes is required, or there is a specificrestriction to the usage of static sensors, such as secrecy. Despite the motivation,systems that use different combinations of static and mobile sensor nodes are appearing and with them, challenges in their interoperation. This is specially the case for surveillance systems.This work focuses on the proposal of solutions for wireless sensor networks including static and mobile sensor nodes specifically regarding cooperative andcontext aware mission setup and performance. Orthogonally to the setup and performance problems and related cooperative and context aware solutions, the goalof this work is to keep the communication costs as low as possible in the executionof the proposed solutions. This concern comes from the fact that communication increases energy consumption, which is a particular issue for energy constrained sensor nodes often used in wireless sensor networks, especially if battery supplied. Inthe case of the mobile nodes, this energy constraint may not be valid, since their motion might need much more energy. For this type of node the problem incommunicating is related to the links’ instabilities and short time windows availableto receive and transmit data. Therefore, it is better to communicate as little as possible. For the interaction among static and mobile sensor nodes, all thesecommunication constraints have to be considered.For the interaction among static sensor nodes, the problems of dissemination and allocation of sensing missions are studied and a solution that explores local information is proposed and evaluated. This solution uses mobile software agentsthat have capabilities to take autonomous decisions about the mission dissemination and allocation using local context information so that the mission’s requirementscan be fulfilled. For mobile wireless sensor networks, the problem studied is how to perform the handover of missions among the nodes according to their movements.This problem assumes that each mission has to be done in a given area of interest. In addition, the nodes are assumed to move according to different movement patterns,passing through these areas. It is also assumed that they have no commitment in staying or moving to a specific area due to the mission that they are carrying. To handle this problem, a mobile agent approach is proposed in which the agents implement the sensing missions’ migration from node to node using geographical context information to decide about their migrations. For the networks combining static and mobile sensor nodes, the cooperation among them is approached by abiologically-inspired mechanism to deliver data from the static to the mobile nodes.The mechanism explores an analogy based on the behaviour of ants building and following trails to provide data delivery, inspired by the ant colony algorithm. It is used to request the displacement of mobile sensors to a given location according tothe need of more sophisticated sensing equipment/devices that they can provide, so that a mission can be accomplished.The proposed solutions are flexible, being able to be applied to different application domains, and less complex than many existing approaches. The simplicity of the solutions neither demands great computational efforts nor large amounts of memory space for data storage. Obtained experimental results provide evidence of the scalability of these proposed solutions, for example by evaluatingtheir cost in terms of communication, among other metrics of interest for eachsolution. These results are compared to those achieved by reference solutions (optimum and flooding-based), providing indications of the proposed solutions’ efficiency. These results are considered close to the optimum one and significantly better than the ones achieved by flooding-based solutions.

  • 318.
    Pignaton de Freitas, Edison
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Heimfarth, Tales
    Computer Science Department, Federal University of Lavras, Lavras, Brazil.
    Netto, Ivayr Farah
    Computer Science Department, Federal University of Lavras, Lavras, Brazil.
    Pereira, Carlos Eduardo
    Institute of Informatics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Ferreira, Armando Morado
    Defense Engineering Graduate Program, Military Institute of Engineering, Rio de Janeiro, Brazil.
    Wagner, Flavio Rech
    Institute of Informatics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
    Larsson, Tony
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Handling Failures of Static Sensor Nodes in Wireless Sensor Network by Use of Mobile Sensors2011In: Proceedings - 25th IEEE International Conference on Advanced Information Networking and Applications Workshops, WAINA 2011, Los Alamitos, Calif.: IEEE Press, 2011, p. 127-134Conference paper (Refereed)
    Abstract [en]

    Node failures in Wireless Sensor Networks composed by static sensor nodes are common due to the nature of the sensor devices and the usually harsh environments in which they are deployed. Node failures can diminish the performance of the network as a whole, thus affecting its functionality in delivering the desired services. For instance, significant regions can become uncovered due to failure of several nearby nodes. This paper reports a study about the use of mobile sensor nodes acting in cooperation with static ones in order to fill gaps created by faulty static nodes. The proposed fault handling mechanism presents alternative policies with pros and cons, depending on the user priorities imposed to the system and the occurrence of failures. A discussion about this topic is presented based on results obtained by simulation of the proposed mechanisms.

  • 319.
    Pignaton de Freitas, Edison
    et al.
    Electrical Engineering Department, University of Brasília, Brazil.
    Heimfarth, Tales
    Department of Computer Science, Federal University of Lavras, CP 3037, Lavras 37200-000, Brazil.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Rech Wagner, Flavio
    Electrical Engineering Department and Institute of Informatics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil .
    Pereira, Carlos Eduardo
    Electrical Engineering Department and Institute of Informatics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil .
    Larsson, Tony
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Cooperation among wirelessly connected static and mobile sensor nodes for surveillance applications2013In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 13, no 10, p. 12903-12928Article in journal (Refereed)
    Abstract [en]

    This paper presents a bio-inspired networking strategy to support the cooperation between static sensors on the ground and mobile sensors in the air to perform surveillance missions in large areas. The goal of the proposal is to provide a low overhead in the communication among sensor nodes, while allocating the mobile sensors to perform sensing activities requested by the static ones. Simulations have shown that the strategy is efficient in maintaining low overhead and achiving the desired coordination. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

  • 320.
    Raase, Sebastian
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    A Dataflow Communications Library for Adapteva's Epiphany2015Report (Other academic)
    Abstract [en]

    Adapteva'€™s Epiphany platform is a scalable low-power manycore architecture. Even though Adapteva provides an ANSI C compatible compiler and runtime as well as a Software Development Kit (eSDK), developing for this platform is not particularly easy.

    At Halmstad University, we are interested in dataflow applications and have developed a suitable communications library (e-commlib) for the Epiphany, which we would like to release under a permissive 2-clause BSD license. Given sufficiently aware compute kernels, e-commlib projects can also be compiled and run in a Linux-pthreads environment, which simplifies both development and (functional) debugging. This Technical Report shall document both e-commlib (version 3) and our surrounding infrastructure.

  • 321.
    Raase, Sebastian
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Exploring the Epiphany manycore architecturefor the Lattice Boltzmann algorithm2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Computational fluid dynamics (CFD) plays an important role in many scientific applications, ranging from designing more effective boat engines or aircraft wings to predicting tomorrow's weather, but at the cost of requiring huge amounts of computing time. Also, traditional algorithms suffer from scalability limitations, making them hard to parallelize massively.

    As a relatively new and promising method for computational fluid dynamics, the Lattice Boltzmann algorithm tries to solve the scalability problems of conventional, but well-tested algorithms in computational fluid dynamics. Through its inherently local structure, it is well suited for parallel processing, and has been implemented on many different kinds of parallel platforms.

    Adapteva's Epiphany platform is a modern, low-power manycore architecture, which is designed to scale up to thousands of cores, and has even more ambitious plans for the future. Hardware support for floating-point calculations makes it a possible choice in scientific settings.

    The goal of this thesis is to analyze the performance of the Lattice Boltzmann algorithm on the Epiphany platform. This is done by implementing and testing the lid cavity test case in two and three dimensions. In real applications, high performance on large lattices with millions of nodes is very important. Although the tested Epiphany implementation scales very good, the hardware does not provide adequate amounts of local memory and external memory bandwidth, currently preventing widespread use in computational fluid dynamics.

  • 322.
    Raase, Sebastian
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    On the Use of a Many-core Processor for Computational Fluid Dynamics Simulations2015In: Procedia Computer Science, ISSN 1877-0509, E-ISSN 1877-0509, Vol. 51, p. 1403-1412Article in journal (Refereed)
    Abstract [en]

    The increased availability of modern embedded many-core architectures supporting floating-point operations in hardware makes them interesting targets in traditional high performance computing areas as well. In this paper, the Lattice Boltzmann Method (LBM) from the domain of Computational Fluid Dynamics (CFD) is evaluated on Adapteva’s Epiphany many-core architecture. Although the LBM implementation shows very good scalability and high floating-point efficiency in the lattice computations, current Epiphany hardware does not provide adequate amounts of either local memory or external memory bandwidth to provide a good foundation for simulation of the large problems commonly encountered in real CFD applications.

  • 323.
    Rak, Jacek
    et al.
    Gdansk University of Technology, Faculty of Electronics, Telecommunications and Informatics, Gdańsk, Poland.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Hutchison, David
    Lancaster University, School of Computing and Communications, Lancaster, United Kingdom.
    Sterbenz, James P. G.
    Lancaster University, School of Computing and Communications, Lancaster, United Kingdom & The University of Kansas, EECS and Information and Telecommunication Technology Center, Lawrence, USA & The Hong Kong Polytechnic University, Hong Kong, China.
    Disciplines and measures of information resilience2017In: ICTON 2017 - 19th International Conference on Transparent Optical Networks 2-6 July 2017, Girona, Catalonia, Spain / [ed] Marek Jaworski & Marian Marciniak, Piscataway: IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    Communication networks have become a fundamental part of many critical infrastructures, playing an important role in information delivery in various failure scenarios triggered e.g., by forces of nature (including earthquakes, tornados, fires, etc.), technology-related disasters (for instance due to power blackout), or malicious human activities. A number of recovery schemes have been defined in the context of network resilience (with the primary focus on communication possibility in failure scenarios including access to a particular host, or information exchange between a certain pair of end nodes). However, because end-users are becoming more and more interested in information itself (regardless of its physical location in the network), it is appropriate to complement the well-defined framework of network resilience with one that addresses information resilience, and to introduce definitions of relevant disciplines and measures, as proposed in this paper. © 2017 IEEE.

  • 324.
    Rak, Jacek
    et al.
    Gdansk University of Technology, Faculty of Electronics, Telecommunications and Informatics, Department of Computer Communications, Gdansk, Poland.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    A Taxonomy of Challenges to Resilient Message Dissemination in VANETs2016In: 2016 17th International Telecommunications Network Strategy and Planning Symposium (Networks): Conference Proceedings / [ed] Zbigniew Dziong, Jean-Charles Gregoire & Jacek Rak, Piscataway: IEEE, 2016, p. 127-132Conference paper (Refereed)
    Abstract [en]

    Inter-vehicular communications is seen as a promising solution to a number of issues related with public road safety, road congestion management, and infotainment. However, Vehicular Ad-hoc NETworks (VANETs) characterized by high mobility of vehicles and facing a number of other issues related with high frequency wireless communications and network disconnections, encounter major challenges related with reliability of message delivery. This issue, despite a number of relevant publications, has not been extensively researched so far. This paper is the first one to provide a definition of information resilience for VANETs and the respective taxonomy of challenges to resilient message delivery for all types of VANET applications (being adaptation of a general taxonomy of challenges for networked systems). Example challenges related to technical aspects of resilient message dissemination for PHY/MAC layer, broadcast transmission, and multi-hop routing are outlined in the final part of the paper. ©2016 by IEEE 

  • 325.
    Ramazanali, Hawar
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Saab Training & Simulation, Husqvarna, Sweden.
    Managing Radio and Energy Resources in LTE-Based Military Training Networks2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The number of wireless connected devices are growing exponentially and the importance of this research area is growing as well to meet the known and looming challenges and expectations. The 5:th Generation telecommunications standard is partly embodied by the Machine-to-Machine (M2M) and Internet of Things (IoT) technologies and standards to handle a big part of these devices and connections. An example within the IoT paradigm is military training systems where each system can consist of thousands of battery operated mobile devices and their shifting requirements shall be fullled in an energy-aware manner to increase battery operating times.

    Military training radio networks enables realistic combat training. The services and features provided in commercial telecommunications networks are desirable in these often proprietary and task specic networks, increasing capabilities and functionalities. To facilitate the current and future R&D of LTE based networks for adoption in military training networks and services this doctoral thesis intends to provide the starting ground for the energy-aware LTE based wireless communications. The thesis first presents general solutions on how to meet traffic deadlines in wireless networks for large number of nodes, and then continues with solutions for energy-aware LTE-based communications for the User Equipments (UEs).

    The work builds on the problem formulation how to provide energy-aware resource handling for LTE-based military training networks from where three research questions are derived. From the research questions we derive different hypotheses and then test these within the investigated area to answer the research questions.

    The contributions of this work are within areas of resource handling and power saving for mobile devices. In the first area an admission control using deterministic analysis is proposed fullling traffic requirements for military training mobile nodes. This admission control is enhanced for multiple-channel base stations, and evaluated using mobile nodes with different heterogeneous traffic requirements. In the second part energy-awareness is in focus for LTE/LTE-A based networks. The main power saving method for LTE/LTE-A UEs, Discontinuous Reception (DRX) mechanism, is evaluated and models for DRX in Idle and Connected state are proposed including metrics for wake-up delay and power saving. Additionally a mean queuing delay analysis is proposed for a variant of the Connected state DRX. Using these models and metrics, practical design guidelines for tuning of DRX parameters are proposed, including optimization of DRX parameters for either minimizing delay or maximizing power saving.

  • 326.
    Ramazanali, Hawar
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Saab Training and Simulation, Huskvarna, Sweden.
    Resource handling for military training networks2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Connected devices are increasing steadily and the number of devices will in soon future be so massive that they are impacting the next generation of wireless standards and are already being considered in them. Machine-to-Machine (M2M) communications and Internet of Things (IoT) sub fields of wireless communications have developed lately with their own research fields and forums. 

    Military training systems are using radio networks of connected devices to provide realistic combat training with new trends of multimedia streaming and lower traffic latency requirements. To facilitate further development of the networks a research goal is formulated to target the improvement of the network in the desired direction. The research goal is to answer how to provide energy efficient wireless communications within the framework of the military training application, meeting requirements of delay, number of network nodes and power efficiency for mobile devices and is broken down to three separate research questions that are each targeted separately as below.

    We have developed an admission control with real-time analysis for a single-frequency base station for mobile nodes with real-time traffic. This scope has been extended to an admission control for a multichannel base station where we also proposed a method on how to maximize the number of mobile nodes, with different traffic requirements including multimedia traffic, in the network. Finally a probabilistic model has been proposed for the Discontinuous Reception (DRX) power saving mechanism for LTE/LTE-A in the 4:th Generation (4G) telecommunications standard. It was also shown how to meet traffic delays while maximizing the power saving factor in the mobile nodes.

  • 327.
    Ramazanali, Hawar
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Saab Training and Simulation, Huskvarna, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Kunert, Kristina
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Military Training Network with Admission Control using Real-Time Analysis2014In: 2014 IEEE 19th International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), Piscataway, NJ: IEEE Press, 2014, p. 249-254, article id 7033244Conference paper (Refereed)
    Abstract [en]

    Military training radio networks typically consist of large numbers of mobile nodes and have to provide real-time (RT) communication between these nodes. This paper introduces a method on how to manage radio resources and provide Quality of Service (QoS) guarantees for heterogeneous traffic by using admission control, deterministic queuing, and scheduling methods. The proposed solution is based on the use of a RT feasibility test in the admission control and earliest deadline first (EDF) scheduling and queuing. This deterministic solution handles heterogeneous traffic through a novel combination of RT downlink and two types of RT uplink dynamic scheduling mechanisms. The uplink scheduling consists of a control packet based mechanism for sporadic RT traffic and a periodic short-latency mechanism for periodic RT traffic. The method presented in this paper is investigated by computer simulation, evaluating its performance and determining the maximum number of nodes supported, given a worst-case user scenario. To the best of our knowledge this is the first centralized protocol designed for a military training network providing application-specific RT support for heterogeneous traffic. ©2014 IEEE.

  • 328.
    Ramazanali, Hawar
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Saab Training and Simulation, Huskvarna, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Bilstrup, Urban
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Multichannel admission control for military training network2015In: 2015 IEEE 18th International Symposium on Real-Time Distributed Computing (ISORC) / [ed] Lisa O’Conner, Los Alamitos, CA: IEEE Computer Society, 2015, p. 150-157Conference paper (Refereed)
    Abstract [en]

    A military training radio network requires support for a large number of mobile nodes with heterogeneous traffic and real-time requirements. We propose a deterministic protocol and an admission control using real-time analysis for a centralized radio network with a multichannel base station. The admission control implements an algorithm for frequency allocation to mobile nodes, and guarantees timely treatment of real-time traffic. The proposed online heuristic frequency allocation algorithm is compared to other known heuristic algorithms: round robin over channels and fill one channel first. The goal with the heuristic algorithms is to maximize the number of supported mobile nodes. Our results show that when the high utilization part of the traffic have shorter deadlines it is advantageous to differentiate different types of nodes onto separate frequencies, whilst if the deadline is increased it is advantageous to mix different types of nodes on each frequency. © Copyright 2015 IEEE

  • 329.
    Ramazanali, Hawar
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Saab Training and Simulation, Huskvarna, Sweden.
    Mesodiakaki, Agapi
    Karlstad University, Department of Mathematics and Computer Science, Karlstad, Sweden.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Verikoukis, Christos
    Telecommunications Technological Centre of Catalonia (CTTC), Castelldefels, Spain.
    Survey of User Association in 5G HetNets2016In: 2016 8th IEEE Latin-American Conference on Communications (LATINCOM) / [ed] Carlos Velasquez-Villada, Piscataway: IEEE Press, 2016, article id 7811565Conference paper (Refereed)
    Abstract [en]

    Heterogeneous networks (HetNets) are considered a key enabling technology to provide high capacity for next generation, also known as fifth generation (5G), networks. However, in order to efficiently exploit the advantages of HetNets and strive towards high network efficiency, efficient user equipment (UE) association is decisive for targeting network performance goals. Therefore, in this work, user association algorithms are surveyed and classified based on the criterion they use for association with the base stations (macrocells or small cells). Special focus is given on the suitability of the user association algorithms for 5G as well as their complexity. © Copyright 2017 IEEE

  • 330.
    Ramazanali, Hawar
    et al.
    SAAB Training and Simulation.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Mean Queuing Delay in LTE DRX2016In: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 5, no 4, p. 444-447, article id 7496866Article in journal (Refereed)
    Abstract [en]

    Energy-efficiency is a crucial requirement for future 5G radio devices. Discontinuous reception (DRX) is a mechanism for power saving in LTE/LTE-A standard. In this letter, a method is developed to compute the mean queuing delay induced by the DRX. In contrast to existing semi-Markovian models, an approach, which combines Markov chains and regenerative processes, is proposed. © 2012 IEEE

  • 331.
    Ramazanali, Hawar
    et al.
    SAAB Training and Simulation, Husqvarna, Sweden.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Performance Evaluation of LTE/LTE-A DRX: A Markovian Approach2015In: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 3, no 3, p. 386-397, article id 7303883Article in journal (Refereed)
    Abstract [en]

    LTE/LTE-A are emerging communication technologies on the way towards 5G telecommunication systems. Ubiquitous adoption of connectivity in between different kinds of sensors, wearable devices and other low-power equipment raises an importance of the energy-efficient wireless communications. In LTE/LTE-A the Discontinuous Reception Mechanism (DRX) aims at power saving of User Equipment (UE) devices. In the paper we present an analysis of DRX, which is novel in two dimensions. First, our analytical approach is different to existing ones due to the use of Markov chain instead of a semi-Markov ones. Secondly, along with the generic traffic models we also analyze the efficiency of DRX for military training application systems, what has not been done before. We suggest few practical recommendations regarding the DRX parameters tuning also. © 2015 IEEE.

  • 332.
    Ramazanali, Hawar
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Saab Training and Simulation, Huskvarna, Sweden.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Tuning of LTE/LTE-A DRX parameters2016In: 2016 IEEE 21st International Workshop on Computer Aided Modelling and Design of Communication Links and Networks (CAMAD), Piscataway, NJ: IEEE, 2016, p. 95-100Conference paper (Refereed)
    Abstract [en]

    The tradeoff between the power saving and the queuing delay in LTE/LTE-A radio devices with Discontinuous Reception (DRX) Mechanism is discussed. Two optimization problems to tune the DRX parameters are formulated. An optimal performance determined by exhaustive search over a large parameter set and a reduced parameter set, obtained by disabling short DRX cycles, is compared.

  • 333.
    Ramazanali, Hawar
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). SAAB Training and Simulation, Huskvarna, Sweden.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Yavuz, Emre
    Ericsson AB, Stockholm, Sweden.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Modeling of LTE DRX in RRC Idle state2017In: 2017 IEEE 22nd International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), 2017Conference paper (Refereed)
    Abstract [en]

    In LTE/LTE-A the Discontinuous Reception (DRX) mechanism is the main approach for power saving in User Equipments (UEs) when in Connected and Idle mode. In this paper, an Idle mode DRX mechanism model is proposed also enabling evaluation of closely related mechanisms such as paging and Tracking Area Update (TAU). Two performance metrics are derived, namely the reachability delay and the power saving factor. © Copyright 2017 IEEE

  • 334.
    Rezk, Nesma
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Purnaprajna, Madhura
    Amrita University, Bengaluru, India.
    Ul-Abdin, Zain
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    E€iffcient Implementation of Convolution Neural Networks Inference On Manycore Architectures2017Conference paper (Refereed)
    Abstract [en]

    The convolution module of convolution neural networks is highly computation demanding. In order to execute a neural network inference on embedded platforms, an ecient implementation of the convolution is required. Low precision parameters can provide an implementation that requires less memory, less computation time, and less power consumption. Nevertheless, streaming the convolution computation over parallelized processing units saves a lot of memory, which is a key concern in memory constrained embedded platforms. In this paper, we show how the convolution module can be implemented on Epiphany manycore architecture. Low precision parameters are used with ternary weights of +1, 0, and -1 values. The computation is done through a pipeline by streaming data through processing units. The proposed approach decreases the memory requirements for CNN implementation and could reach up to 282 GOPS and up to 5.6 GOPs/watt.

  • 335.
    Rezk, Nesma
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Purnaprajna, Madhura
    Amrita University, Bengaluru, India.
    Ul-Abdin, Zain
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Streaming Tiles: Flexible Implementation of Convolution Neural Networks Inference on Manycore Architectures2018In: 2018 IEEE International Parallel and Distributed Processing Symposium Workshops (IPDPSW), Los Alamitos: IEEE Computer Society, 2018, p. 867-876Conference paper (Refereed)
    Abstract [en]

    Convolution neural networks (CNN) are extensively used for deep learning applications such as image recognition and computer vision. The convolution module of these networks is highly compute-intensive. Having an efficient implementation of the convolution module enables realizing the inference part of the neural network on embedded platforms. Low precision parameters require less memory, less computation time, and less power consumption while achieving high classification accuracy. Furthermore, streaming the data over parallelized processing units saves a considerable amount of memory, which is a key concern in memory constrained embedded platforms. In this paper, we explore the design space for streamed CNN on Epiphany manycore architecture using varying precisions for weights (ranging from binary to 32-bit). Both AlexNet and GoogleNet are explored for two different memory sizes of Epiphany cores. We are able to achieve competitive performance for both Alexnet and GoogleNet with respect to emerging manycores. Furthermore, the effects of different design choices in terms of precision, memory size, and the number of cores are evaluated by applying the proposed method.

  • 336.
    Ruzicka, Theophil
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Model based Design of a Sailboat Autopilot2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 337.
    Sajadian, S.
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Ibrahim, A.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    de Freitas, Edison Pignaton
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Larsson, Tony
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS).
    Improving Connectivity of Nodes in Mobile WSN2011In: Advanced Information Networking and Applications (AINA), 2011 IEEE International Conference on, Los Alamitos: IEEE Computer Society, 2011, p. 364-371Conference paper (Refereed)
    Abstract [en]

    How to measure and maintain connectivity is an important issue in ad hoc networks. A special case of such network is Wireless Sensor Networks (WSN), which are often deployed in harsh environments and also susceptible to a number of problems that may negatively affect the connectivity among the nodes. An additional factor that increases the cost of connectivity maintenance in ad hoc networks is when the nodes can move. When it comes to the WSN domain, this aspect is still more problematic, as the often small sensor nodes have in general a limited energy budget, and then should not use too much energy in the management of their connectivity. The goal of this work is to choose a topology for mobile WSN and improve the network connectivity as a whole while considering and influencing the energy consumption among all the nodes in the network. Different network topologies are considered and discussed. After evaluation of the pros and cons of the estimation quality when applied to each studied topology, a clustered hierarchical algorithm was chosen for network deployment. By means of a link estimator and considering different variables, a metric have been defined to estimate the link reliability. As a result, improved network connectivity is reported.

  • 338.
    Salama, Cherif
    et al.
    Ain Shams University, Cairo, Egypt.
    Taha, Walid
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Rice University, Houston, Texas, USA.
    Increasing Verilog’s Generative Power2014Conference paper (Refereed)
    Abstract [en]

    To cope with more complex circuits, well-understood higher-level abstraction mechanisms are needed. Verilog is already equipped with promising generative constructs making it possible to concisely describe a family of circuits as a parameterized module; however these constructs suffer from limited expressivity even in the latest IEEE standard. In this paper, we address generative constructs expressivity limitations, identifying the key extensions needed to overcome these limitations, and showing how to incorporate them in Verilog in a disciplined, backward-compatible way.

  • 339.
    Sardis, Fragkiskos
    et al.
    Department of Informatics, King’s College London, London, United Kingdom.
    Mapp, Glenford
    School of Science and Technology, Middlesex University, London, United Kingdom.
    Loo, Jonathan
    School of Science and Technology, Middlesex University, London, United Kingdom.
    Aiash, Mahdi
    School of Science and Technology, Middlesex University, London, United Kingdom.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Investigating a Mobility-Aware QoS Model for Multimedia Streaming Rate Adaptation2015In: Journal of Electrical and Computer Engineering, ISSN 2090-0147, E-ISSN 2090-0155, Vol. 2015, article id 548638Article in journal (Refereed)
    Abstract [en]

    Supporting high quality multimedia streaming on wireless devices poses several challenges compared to wired networks due to the high variance in network performance encountered in the mobile environment. Although rate adaptation is commonly used in multimedia applications to compensate for fluctuations in network performance, it is a reactive mechanism which is not aware of the frequently changing connectivity that may occur on mobile devices. This paper proposed a performance evaluation model for multimedia streaming applications that is aware of user mobility and network performance. We presented an example of mathematical solution to the model and demonstrated the functionality using common mobility and connectivity examples that may be found in an urban environment. The proposed model is evaluated based on this functionality and how it may be used to enhance application performance. © 2015 Fragkiskos Sardis et al.

  • 340.
    Sardis, Fragkiskos
    et al.
    School of Science and Technology, Middlesex University, London, United Kingdom.
    Mapp, Glenford
    School of Science and Technology, Middlesex University, London, United Kingdom.
    Loo, Jonathan
    School of Science and Technology, Middlesex University, London, United Kingdom.
    Aiash, Mahdi
    School of Science and Technology, Middlesex University, London, United Kingdom.
    Vinel, Alexey
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    On the Investigation of Cloud-Based Mobile Media Environments With Service-Populating and QoS-Aware Mechanisms2013In: IEEE transactions on multimedia, ISSN 1520-9210, E-ISSN 1941-0077, Vol. 15, no 4, p. 769-777Article in journal (Refereed)
    Abstract [en]

    Recent advances in mobile devices and network technologies have set new trends in the way we use computers and access networks. Cloud Computing, where processing and storage resources are residing on the network is one of these trends. The other is Mobile Computing, where mobile devices such as smartphones and tablets are believed to replace personal computers by combining network connectivity, mobility, and software functionality. In the future, these devices are expected to seamlessly switch between different network providers using vertical handover mechanisms in order to maintain network connectivity at all times. This will enable mobile devices to access Cloud Services without interruption as users move around. Using current service delivery models, mobile devices moving from one geographical location to another will keep accessing those services from the local Cloud of their previous network, which might lead to moving a large volume of data over the Internet backbone over long distances. This scenario highlights the fact that user mobility will result in more congestion on the Internet. This will degrade the Quality of Service and by extension, the Quality of Experience offered by the services in the Cloud and especially multimedia services that have very tight temporal constraints in terms of bandwidth and jitter. We believe that a different approach is required to manage resources more efficiently, while improving the Quality of Service and Quality of Experience of mobile media services. This paper introduces a novel concept of Cloud-Based Mobile Media Service Delivery in which services run on localized public Clouds and are capable of populating other public Clouds in different geographical locations depending on service demands and network status. Using an analytical framework, this paper argues that as the demand for specific services increases in a location, it might be more efficient to move those services closer to that location. This will prevent the Internet backbone from experiencing high traffic loads due to multimedia streams and will offer service providers an automated resource allocation and management mechanism for their services. © 1999-2012 IEEE.

  • 341.
    Savas, Süleyman
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Hardware/Software Co-Design of Heterogeneous Manycore Architectures2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the era of big data, advanced sensing, and artificial intelligence, the required computation power is provided mostly by multicore and manycore architectures. However, the performance demand keeps growing. Thus the computer architectures need to continue evolving and provide higher performance. The applications, which are executed on the manycore architectures, are divided into several tasks to be mapped on separate cores and executed in parallel. Usually these tasks are not identical and may be executed more efficiently on different types of cores within a heterogeneous architecture. Therefore, we believe that the heterogeneous manycores are the next step for the computer architectures. However, there is a lack of knowledge on what form of heterogeneity is the best match for a given application or application domain. This knowledge can be acquired through designing these architectures and testing different design configurations. However, designing these architectures is a great challenge. Therefore, there is a need for an automated design method to facilitate the architecture design and design space exploration to gather knowledge on architectures with different configurations. Additionally, it is already difficult to program manycore architectures efficiently and this difficulty will only increase further with the introduction of heterogeneity due to the increase in the complexity of the architectures, unless this complexity is somehow hidden. There is a need for software development tools to facilitate the software development for these architectures and enable portability of the same software across different manycore platforms.

    In this thesis, we first address the challenges of the software development for manycore architectures. We evaluate a dataflow language (CAL) and a source-to-source compilation framework (Cal2Many) with several case studies in order to reveal their impact on productivity and performance of the software. The language supports task level parallelism by adopting actor model and the framework takes CAL code and generates implementations in the native language of several different architectures.

    In order to address the challenge of custom hardware development, we first evaluate a commercial manycore architecture namely Epiphany and identify its demerits. Then we study manycore architectures in order to reveal possible uses of heterogeneity in manycores and facilitate choice of architecture for software and hardware development. We define a taxonomy for manycore architectures that is based on the levels of heterogeneity they contain and discuss the benefits and drawbacks of these levels. We finally develop and evaluate a design method to design heterogeneous manycore architectures customized based on application requirements. The architectures designed with this method consist of cores with application specific accelerators. The majority of the design method is automated with software tools, which support different design configurations in order to increase the productivity of the hardware developer and enable design space exploration.

    Our results show that the dataflow language, together with the software development tool, decreases software development efforts significantly (25-50%), while having a small impact (2-17%) on the performance. The evaluation of the design method reveal that the performance of automatically generated accelerators is between 96-100% of the performance of their manually developed counterparts. Additionally, it is possible to increase the performance of the architectures by increasing the number of cores and using application specific accelerators, usually with a cost on the area usage. However, under certain circumstances, using accelerator may lead to avoiding usage of large general purpose components such as the floating-point unit and therefore improves the area utilization. Eventually, the final impact on the performance and area usage depends on the configurations. When compared to the Epiphany architecture, which is a commercial homogeneous manycore, the generated manycores show competitive results. We can conclude that the automated design method simplifies heterogeneous manycore architecture design and facilitates design space exploration with the use of configurable parameters.

  • 342.
    Savas, Süleyman
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Utilizing Heterogeneity in Manycore Architectures for Streaming Applications2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the last decade, we have seen a transition from single-core to manycore in computer architectures due to performance requirements and limitations in power consumption and heat dissipation. The first manycores had homogeneous architectures consisting of a few identical cores. However, the applications, which are executed on these architectures, usually consist of several tasks requiring different hardware resources to be executed efficiently. Therefore, we believe that utilizing heterogeneity in manycores will increase the efficiency of the architectures in terms of performance and power consumption. However, development of heterogeneous architectures is more challenging and the transition from homogeneous to heterogeneous architectures will increase the difficulty of efficient software development due to the increased complexity of the architecture. In order to increase the efficiency of hardware and software development, new hardware design methods and software development tools are required. Additionally, there is a lack of knowledge on the performance of applications when executed on manycore architectures.

    The transition began with a shift from single-core architectures to homogeneous multicore architectures consisting of a few identical cores. It now continues with a shift from homogeneous architectures with identical cores to heterogeneous architectures with different types of cores specialized for different purposes. However, this transition has increased the complexity of architectures and hence the complexity of software development and execution. In order to decrease the complexity of software development, new software tools are required. Additionally, there is a lack of knowledge on what kind of heterogeneous manycore design is most efficient for different applications and what are the performances of these applications when executed on current commercial manycores.

    This thesis studies manycore architectures in order to reveal possible uses of heterogeneity in manycores and facilitate choice of architecture for software and hardware developers. It defines a taxonomy for manycore architectures that is based on the levels of heterogeneity they contain and discusses benefits and drawbacks of these levels. Additionally, it evaluates several applications, a dataflow language (CAL), a source-to-source compilation framework (Cal2Many), and a commercial manycore architecture (Epiphany). The compilation framework takes implementations written in the dataflow language as input and generates code targetting different manycore platforms. Based on these evaluations, the thesis identifies the bottlenecks of the architecture. It finally presents a methodology for developing heterogeneoeus manycore architectures which target specific application domains.

    Our studies show that using different types of cores in manycore architectures has the potential to increase the performance of streaming applications. If we add specialized hardware blocks to a core, the performance easily increases by 15x for the target application while the core size increases by 40-50% which can be optimized further. Other results prove that dataflow languages, together with software development tools, decrease software development efforts significantly (25-50%) while having a small impact (2-17%) on the performance.

  • 343.
    Savas, Süleyman
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Gebrewahid, Essayas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Ul-Abdin, Zain
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Yang, Mingkun
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    An Evaluation of Code Generation of Dataflow Languages on Manycore Architectures2014In: RTCSA 2014: 2014 IEEE 20th International Conference on Embedded and Real-Time Computing Systems and Applications, Piscataway, NJ: IEEE Press, 2014, article id 6910501Conference paper (Refereed)
    Abstract [en]

    Today computer architectures are shifting from single core to manycores due to several reasons such as performance demands, power and heat limitations. However, shifting to manycores results in additional complexities, especially with regard to efficient development of applications. Hence there is a need to raise the abstraction level of development techniques for the manycores while exposing the inherent parallelism in the applications. One promising class of programming languages is dataflow languages and in this paper we evaluate and optimize the code generation for one such language, CAL. We have also developed a communication library to support the inter-core communication.The code generation can target multiple architectures, but the results presented in this paper is focused on Adapteva's many core architecture Epiphany.We use the two-dimensional inverse discrete cosine transform (2D-IDCT) as our benchmark and compare our code generation from CAL with a hand-written implementation developed in C. Several optimizations in the code generation as well as in the communication library are described, and we have observed that the most critical optimization is reducing the number of external memory accesses. Combining all optimizations we have been able to reduce the difference in execution time between auto-generated and hand-written implementations from a factor of 4.3x down to a factor of only 1.3x. ©2014 IEEE.

  • 344.
    Savas, Süleyman
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Hertz, Erik
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Ul-Abdin, Zain
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Efficient Single-Precision Floating-Point Division Using Harmonized Parabolic Synthesis2017In: 2017 IEEE Computer Society Annual Symposium on VLSI: ISVLSI 2017 / [ed] Michael Hübner, Ricardo Reis, Mircea Stan & Nikolaos Voros, Los Alamitos: IEEE, 2017Conference paper (Refereed)
    Abstract [en]

    This paper proposes a novel method for performing division on floating-point numbers represented in IEEE-754 single-precision (binary32) format. The method is based on an inverter, implemented as a combination of Parabolic Synthesis and second-degree interpolation, followed by a multiplier. It is implemented with and without pipeline stages individually and synthesized while targeting a Xilinx Ultrascale FPGA.

    The implementations show better resource usage and latency results when compared to other implementations based on different methods. In case of throughput, the proposed method outperforms most of the other works, however, some Altera FPGAs achieve higher clock rate due to the differences in the DSP slice multiplier design.

    Due to the small size, low latency and high throughput, the presented floating-point division unit is suitable for high performance embedded systems and can be integrated into accelerators or be used as a stand-alone accelerator.

  • 345.
    Savas, Süleyman
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Raase, Sebastian
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Gebrewahid, Essayas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Ul-Abdin, Zain
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Dataflow Implementation of QR Decomposition on a Manycore2016In: MES '16: Proceedings of the Third ACM International Workshop on Many-core Embedded Systems, New York, NY: ACM Press, 2016, p. 26-30Conference paper (Refereed)
    Abstract [en]

    While parallel computer architectures have become mainstream, application development on them is still challenging. There is a need for new tools, languages and programming models. Additionally, there is a lack of knowledge about the performance of parallel approaches of basic but important operations, such as the QR decomposition of a matrix, on current commercial manycore architectures.

    This paper evaluates a high level dataflow language (CAL), a source-to-source compiler (Cal2Many) and three QR decomposition algorithms (Givens Rotations, Householder and Gram-Schmidt). The algorithms are implemented both in CAL and hand-optimized C languages, executed on Adapteva's Epiphany manycore architecture and evaluated with respect to performance, scalability and development effort.

    The performance of the CAL (generated C) implementations gets as good as 2\% slower than the hand-written versions. They require an average of 25\% fewer lines of source code without significantly increasing the binary size. Development effort is reduced and debugging is significantly simplified. The implementations executed on Epiphany cores outperform the GNU scientific library on the host ARM processor of the Parallella board by up to 30x. © 2016 Copyright held by the owner/author(s).

  • 346.
    Savas, Süleyman
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Ul-Abdin, Zain
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Nordström, Tomas
    RISE Research Institutes of Sweden, Gothenburg, Sweden.
    A Configurable Two Dimensional Mesh Network-on-Chip Implementation in Chisel2019Conference paper (Refereed)
    Abstract [en]

    On-chip communication plays a significant role in the performance of manycore architectures. Therefore, they require a proper on-chip communication infrastructure that can scale with the number of the cores. As a solution, network-on-chip structures have emerged and are being used.

    This paper presents description of a two dimensional mesh network-on-chip router and a network interface, which are implemented in Chisel to be integrated to the rocket chip generator that generates RISC-V (rocket) cores. The router is implemented in VHDL as well and the two implementations are verified and compared.

    Hardware resource usage and performance of different sized networks are analyzed. The implementations are synthesized for a Xilinx Ultrascale FPGA via Xilinx tools for the hardware resource usage and clock frequency results. The performance results including latency and throughput measurements with different traffic patterns, are collected with cycle accurate emulations. 

    The implementations in Chisel and VHDL do not show a significant difference. Chisel requires around 10% fewer lines of code, however, the difference in the synthesis results is negligible.Our latency result are better than the majority of the other studies. The other results such as hardware usage, clock frequency, and throughput are competitive when compared to the related works.

  • 347.
    Savas, Süleyman
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Ul-Abdin, Zain
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    A Framework to Generate Domain-Specific Manycore Architectures from Dataflow Programs2019In: Microprocessors and microsystems, ISSN 0141-9331, E-ISSN 1872-9436Article in journal (Refereed)
    Abstract [en]

    In the last 15 years we have seen, as a response to power and thermal limits for current chip technologies, an explosion in the use of multiple and even many computer cores on a single chip. But now, to further improve performance and energy efficiency, when there are potentially hundreds of computing cores on a chip, we see a need for a specialization of individual cores and the development of heterogeneous manycore computer architectures.

    However, developing such heterogeneous architectures is a significant challenge. Therefore, we propose a design method to generate domain specific manycore architectures based on RISC-V instruction set architecture and automate the main steps of this method with software tools. The design method allows generation of manycore architectures with different configurations including core augmentation through instruction extensions and custom accelerators. The method starts from developing applications in a high-level dataflow language and ends by generating synthesizable Verilog code and cycle accurate emulator for the generated architecture.

    We evaluate the design method and the software tools by generating several architectures specialized for two different applications and measure their performance and hardware resource usages. Our results show that the design method can be used to generate specialized manycore architectures targeting applications from different domains. The specialized architectures show at least 3 to 4 times better performance than the general purpose counterparts. In certain cases, replacing general purpose components with specialized components saves hardware resources. Automating the method increases the speed of architecture development and facilitates the design space exploration of manycore architectures.

  • 348.
    Savas, Süleyman
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Ul-Abdin, Zain
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Designing Domain Specific Heterogeneous Manycore Architectures Based on Building Blocks2018Manuscript (preprint) (Other academic)
    Abstract [en]

    Performance and power requirements has pushed computer architectures from single core to manycores. These requirements now continue pushing the manycores with identical cores (homogeneous) to manycores with specialized cores (heterogeneous). However designing heterogeneous manycores is a challenging task due to the complexity of the architectures. We propose an approach for designing domain specific heterogeneous manycore architectures based on building blocks. These blocks are defined as the common computations of the applications within a domain. The objective is to generate heterogeneous architectures by integrating many of these blocks to many simple cores and connect the cores with a networkon-chip. The proposed approach aims to ease the design of heterogeneous manycore architectures and facilitate usage of dark silicon concept. As a case study, we develop an accelerator based on several building blocks, integrate it to a RISC core and synthesize on a Xilinx Ultrascale FPGA. The results show that executing a hot-spot of an application on an accelerator based on building blocks increases the performance by 15x, with room for further improvement. The area usage increases as well, however there are potential optimizations to reduce the area usage. © 2018 by the authors

  • 349.
    Savas, Süleyman
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Ul-Abdin, Zain
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Designing Domain-Specific Heterogeneous Architectures from Dataflow Programs2018In: Computers, ISSN 2073-431X, Vol. 7, no 2, article id 27Article in journal (Refereed)
    Abstract [en]

    The last ten years have seen performance and power requirements pushing computer architectures using only a single core towards so-called manycore systems with hundreds of cores on a single chip. To further increase performance and energy efficiency, we are now seeing the development of heterogeneous architectures with specialized and accelerated cores. However, designing these heterogeneous systems is a challenging task due to their inherent complexity. We proposed an approach for designing domain-specific heterogeneous architectures based on instruction augmentation through the integration of hardware accelerators into simple cores. These hardware accelerators were determined based on their common use among applications within a certain domain.The objective was to generate heterogeneous architectures by integrating many of these accelerated cores and connecting them with a network-on-chip. The proposed approach aimed to ease the design of heterogeneous manycore architectures—and, consequently, exploration of the design space—by automating the design steps. To evaluate our approach, we enhanced our software tool chain with a tool that can generate accelerated cores from dataflow programs. This new tool chain was evaluated with the aid of two use cases: radar signal processing and mobile baseband processing. We could achieve an approximately 4x improvement in performance, while executing complete applications on the augmented cores with a small impact (2.5–13%) on area usage. The generated accelerators are competitive, achieving more than 90% of the performance of hand-written implementations.

  • 350.
    Savas, Süleyman
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Yassin, Atwa
    Halmstad University, School of Information Technology.
    Nordström, Tomas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Ul-Abdin, Zain
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Using Harmonized Parabolic Synthesis to Implement a Single-Precision Floating-Point Square Root Unit2019Conference paper (Refereed)
    Abstract [en]

    This paper proposes a novel method for performing square root operation on floating-point numbers represented in IEEE-754 single-precision (binary32) format. The method is implemented using Harmonized Parabolic Synthesis. It is implemented with and without pipeline stages individually and synthesized for two different Xilinx FPGA boards.

    The implementations show better resource usage and latency results when compared to other similar works including Xilinx intellectual property (IP) that uses the CORDIC method. Any method calculating the square root will make approximation errors. Unless these errors are distributed evenly around zero, they can accumulate and give a biased result. An attractive feature of the proposed method is the fact that it distributes the errors evenly around zero, in contrast to CORDIC for instance.

    Due to the small size, low latency, high throughput, and good error properties, the presented floating-point square root unit is suitable for high performance embedded systems. It can be integrated into a processor’s floating point unit or be used as astand-alone accelerator.

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