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  • 251.
    Bellalta, Boris
    et al.
    Universitat Pompeu Fabra, Barcelona, Spain.
    Belyaev, Evgeny
    Tampere University of Technology, Finland.
    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).
    Performance evaluation of IEEE 802.11p-enabled vehicular video surveillance system2014In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 18, no 4, p. 708-711Article in journal (Refereed)
    Abstract [en]

    Prospective IEEE 802.11p-based vehicular surveillance system, where video from the vehicle on-board camera is transmitted to the management center, is considered. Multi-hop transmission from the vehicle to the nearest roadside unit and then-via other roadside units-to the gateway is addressed. In this letter we assess the feasibility of such system by analyzing the video end-to-end distortion for a target vehicle, located several hops away from the gateway, when it is alone or there are also other vehicles transmitting video. We demonstrate the importance of dynamic adaptation of the video bit rate of each vehicle depending on the number and positions of the participating vehicles. © 2014 IEEE.

  • 252.
    Bellalta, Boris
    et al.
    Department of Information Technologies and Communications, Universitat Pompeu Fabra, Barcelona, Spain.
    Faridi, Azadeh
    Department of Information Technologies and Communications, Universitat Pompeu Fabra, Barcelona, Spain.
    Staehle, Dirk
    Department of Computer Science, University of Würzburg, Würzburg, Germany.
    Barcelo, Jaume
    Department of Information Technologies and Communications, Universitat Pompeu Fabra, Barcelona, Spain.
    Vinel, Alexey
    Department of Electronics and Communication Engineering, Tampere University of Technology, Tampere, Finland.
    Oliver, Miquel
    Department of Information Technologies and Communications, Universitat Pompeu Fabra, Barcelona, Spain.
    Performance analysis of CSMA/CA protocols with multi-packet transmission2013In: Computer Networks, ISSN 1389-1286, E-ISSN 1872-7069, Vol. 57, no 14, p. 2675-2688Article in journal (Refereed)
    Abstract [en]

    Wireless objects equipped with multiple antennas are able to simultaneously transmit multiple packets by exploiting the channel's spatial dimensions. In this paper, we study the benefits of such Multiple Packet Transmission (MPT) approach, when it is used in combination with a Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol for fully interconnected networks, addressing the interactions between the two mechanisms and showing the performance gains that can be achieved. To this end, a very simple Media Access Control (MAC) protocol that captures the fundamental properties and tradeoffs of a CSMA/CA channel access protocol supporting MPT is introduced. Using this protocol as a reference, a new analytical model is presented for the case of non-saturated traffic sources with finite buffer space. Simulation results show that the analytical model is able to accurately characterize the steady-state behavior of the reference protocol for different number of antennas and different traffic loads, providing a useful tool for understanding the performance gains achieved by MAC protocols supporting MPT. © 2013 Elsevier B.V. All rights reserved.

  • 253.
    Bellalta, Boris
    et al.
    Pompeu Fabra University, Barcelona, Spain.
    Vinel, Alexey
    Chatzimisios, Periklis
    Alexander Technological Educational Institute of Thessaloniki, Thessaloniki, Greece.
    Bruno, Raffaele
    Istituto di Informatica e Telematica (IIT) / Consiglio Nazionale delle Ricerche (CNR), Pisa, Italy.
    Wang, Chonggang
    InterDigital Communications, King of Prussia, PA, USA.
    Research advances and standardization activities in WLANs2014In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 39, p. 1-2Article in journal (Refereed)
  • 254.
    Bellalta, Boris
    et al.
    Universitat Pompeu Fabra, Barcelona, Spain.
    Vinel, AlexeyDepartment of Communications Engineering, Tampere University of Technology, Finland.Jonsson, MagnusHalmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).Barcelo, JaumeUniversitat Pompeu Fabra, Barcelona, Spain.Maslennikov, RomanUniversity of Nizhny Novgorod, Russia.Chatzimisios, PeriklisAlexander Technological Educational Institute of Thessaloniki Sindos, Greece.Malone, DavidNational University of Ireland, Maynooth, Ireland.
    Multiple Access Communications: 5th International Workshop, MACOM 2012, Maynooth, Ireland, November 19-20, 2012. Proceedings2012Conference proceedings (editor) (Refereed)
    Abstract [en]

    The proceedings contain 18 papers. The topics discussed include: network coding as a WiMAX link reliability mechanism; initialization procedure of wireless network coding with hierarchical decode and forward strategy in random connectivity networks; a coded DHA FH OFDMA system with a noncoherent ML detector under multitone jamming; analysis of inter-RSU beaconing interference in VANETs; survey of energy efficient tracking and localization techniques in buildings using optical and wireless communication media; network coding as a WiMAX link reliability mechanism: an experimental demonstration; spectrum sensing with USRP-E110; power control for wireless networks with a limited number of channels; a measurement study for predicting throughput from LQI and RSSI; reality considerations when designing a TDMA-FDMA based link-layer for real-time WSN; and wireless groupcast routing with palette of transmission methods.

  • 255.
    Bellalta, Boris
    et al.
    Universitat Pompeu Fabra, Barcelona, Spain .
    Vinel, Alexey
    Department of Communications Engineering, Tampere University of Technology, Tampere, Finland.
    Oliver, Miquel
    Universitat Pompeu Fabra, Barcelona, Spain .
    An upper-bound queueing model for Multi-rate Downlink SDMA systems2010In: 2010 International Congress on Ultra Modern Telecommunications and Control Systems and Workshops, ICUMT 2010, 2010, p. 1212-1217Conference paper (Refereed)
  • 256.
    Bellalta, Boris
    et al.
    Universitat Pompeu Fabra, Barcelona, Spain.
    Zocca, Alessandro
    Eindhoven University of Technology, Eindhoven, The Netherlands.
    Cano, Cristina
    Hamilton Institute, Maynooth, Ireland.
    Checco, Alessandro
    Hamilton Institute, Maynooth, Ireland.
    Barcelo, Jaume
    Universitat Pompeu Fabra, Barcelona, Spain.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Throughput Analysis in CSMA/CA Networks Using Continuous Time Markov Networks: A Tutorial2014In: Wireless Networking for Moving Objects / [ed] Ivan Ganchev, Marília Curado, Andreas Kassler, Cham: Springer, 2014, p. 115-133Chapter in book (Refereed)
    Abstract [en]

    This book chapter introduces the use of Continuous Time Markov Networks (CTMN) to analytically capture the operation of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) networks. It is of tutorial nature, and it aims to be an introduction on this topic, providing a clear and easy-to-follow description. To illustrate how CTMN can be used, we introduce a set of representative and cutting-edge scenarios, such as Vehicular Ad-hoc Networks (VANETs), Power Line Communication networks and multiple overlapping Wireless Local Area Networks (WLANs). For each scenario, we describe the specific CTMN, obtain its stationary distribution and compute the throughput achieved by each node in the network. Taking the per-node throughput as reference, we discuss how the complex interactions between nodes using CSMA/CA have an impact on system performance.

  • 257.
    Beltramelli, Luca
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Modelling of EnergyConsumption in IEEE 802.11.ah Networks for M2M Traffic2016In: Proceedings of SNCNW 2016: The 12th Swedish National Computer Networking Workshop, 2016, p. 38-41Conference paper (Refereed)
    Abstract [en]

    IEEE 802.11ah is a sub-1 GHz standard designed to meet the requirements of future machine-to-machine (M2M) communications. The standard should be able to support use cases for the M2M communications with thousands of stations capable of generating both periodic and aperiodic traffic for a single access point. In some cases, like environmental and agricultural monitoring. the nodes are typically powered by battery or through energy harvesting. For this application it is important for the communication to be energy efficient. IEEE 802.11ah introduces new energy saving mechanisms and a novel channel access mechanism to achieve this objective even for networks with a large nodes number. This work proposes a mathematical model to compute the energy consumption of an IEEE 802.11ah network.

  • 258.
    Beltramelli, Luca
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Österberg, Patrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Jennehag, Ulf
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Hybrid MAC Mechanism for Energy Efficient Communication in IEEE 802.11ah2017In: Proceedings of the 2017 IEEE International Conference on Industrial Technology (ICIT), IEEE, 2017, p. 1295-1300, article id 7915550Conference paper (Refereed)
    Abstract [en]

    Many applications for machine-to-machine (M2M) communications are characterized by large numbers of devices with sporadic transmissions and subjected to low energy budgets. This work addresses the importance of energy consumption by proposing a new Medium Access Control (MAC) mechanism for improving the energy efficiency of IEEE 802.11ah, a standard targeting M2M communication. We propose to use the features of IEEE 802.11ah MAC to realize a hybrid contention-reservation mechanism for the transmission of uplink traffic. In the proposed mechanism, any device with a buffered packet will first notify the Access Point (AP) during a contention phase before being given a reserved timeslot for the data transmission. We develop a mathematical model to analyse the energy consumption ofthe proposed mechanism and of IEEE 802.11ah. The results show that for a monitoring scenario, the proposed contention reservation mechanism reduces the energy consumption for a successful uplink data transmission by up to 55%.

  • 259. Beltran, M
    et al.
    Deng, L
    Pang, Xiaodan
    RISE ACREO AB.
    Zhang, X
    Arlunno, V
    Zhao, Y
    Yu, X
    Llorente, R
    Liu, D
    Tafur Monroy, I
    Single- and Multiband OFDM Photonic Wireless Links in the 75-110 GHz Band EmployingOptical Combs2012In: IEEE Photonics Journal, Vol. 4, no 5, p. 2027-2036Article in journal (Refereed)
  • 260. Beltrán, Marta
    et al.
    Deng, Lei
    Pang, Xiaodan
    RISE ACREO AB.
    Zhang, Xu
    Arlunno, Valeria
    Zhao, Ying
    Yu, Xianbin
    Llorente, Roberto
    Liu, Deming
    Tafur Monroy, Idelfonso
    38.2-Gb/s Optical-Wireless Transmission in 75-110 GHz Based on Electrical OFDM with Optical Comb Expansion2012In: Optical Fiber Communication Conference, 2012Conference paper (Refereed)
  • 261.
    Belyaev, Evgeny
    et al.
    Department of Signal Processing, Tampere University of Technology, Tampere, Finland.
    Molchanov, Pavlo
    Department of Signal Processing, Tampere University of Technology, Tampere, Finland.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Department of Electronics and Communication Engineering, Tampere University of Technology, Tampere, Finland.
    Koucheryavy, Yevgeni
    Department of Electronics and Communication Engineering, Tampere University of Technology, Tampere, Finland.
    The Use of Automotive Radars in Video-Based Overtaking Assistance Applications2013In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 14, no 3, p. 1035-1042, article id 649464Article in journal (Refereed)
    Abstract [en]

    Overtaking on rural roads may cause severe accidents when oncoming traffic is detected by a driver too late, or its speed is underestimated. Recently proposed cooperative overtaking assistance systems are based on real-time video transmission, where a video stream captured with a camera installed at the windshield of a vehicle is compressed, broadcast through the wireless channel, and displayed to the drivers of vehicles driving behind. In such a system, it is of ultimate importance to deliver video information about the opposite lane with low end-to-end latency and good visual quality. In this paper, we propose reallocating the wireless channel resources in favor of the part of the captured video frame containing the image of the oncoming vehicle. To achieve this goal, we apply automotive radar for oncoming vehicle detection, and we use the image of this vehicle as a region-of-interest (ROI) for the video rate control. We present the theoretical framework, which describes the basics of such an approach and can serve as a useful guideline for the future practical implementation of the overtaking assistance systems. The benefits of our proposal are demonstrated in relation to the practical scenario of H.264/Advance Video Coding (AVC), IEEE 802.11p/Wireless Access for Vehicular Environments (WAVE) intervehicle communication standards, and currently used automotive radars.

  • 262.
    Belyaev, Evgeny
    et al.
    Technical University of Denmark, Lyngby, Denmark.
    Moreschini, Sergio
    Tampere University of Technology, Tampere, Finland.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Uncoordinated multi-user video streaming in VANETs using Skype2017In: 2017 IEEE 22nd International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), 2017Conference paper (Refereed)
    Abstract [en]

    Real-time video delivery in Vehicle-to-Infrastructure (V2I) scenario enables a variety of multimedia vehicular services. We conduct experiments with Dedicated Short Range Communications (DSRC) transceivers located in the mutual proximity and exchanging Skype video calls traffic. We demonstrate that the lack of coordination between the users both at the application as well as Medium Access Control (MAC) layers results in problems with quality of service provisioning even for the setup without vehicular mobility. © Copyright 2017 IEEE

  • 263.
    Belyaev, Evgeny
    et al.
    Tampere University of Technology, Tampere, Finland.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Poster: Target Packet Loss Selection for Inter-Packet Loss Protection for Video Streaming Over VANETs2014In: 2014 IEEE Vehicular Networking Conference (VNC) / [ed] Falko Dressler, Onur Altintas, Suman Banerjee, Björn Scheuermann & David Eckhoff, Piscataway, N.J.: IEEE Press, 2014, p. 197-198Conference paper (Refereed)
    Abstract [en]

    This work is dedicated to a live video streaming in vehicular networks where the application-based inter-packet forward error correction is used for the packet loss protection. A practical way to apply such a protection at the video encoder side for the unknown channel loss rate is proposed. Experimental results which demonstrate the performance for the proposed approach for a scalable extension of the H.264/AVC standard (H.264/SVC) and for the non-standardized video codec based on three-dimensional discrete wavelet transform (3-D DWT) are provided.

  • 264.
    Belyaev, Evgeny
    et al.
    Tampere University of Technology, Tampere, Finland .
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES). Tampere University of Technology, Tampere, Finland.
    Egiazarian, Karen
    Tampere University of Technology, Tampere, Finland.
    Koucheryavy, Yevgeni
    Tampere University of Technology, Tampere, Finland.
    Power Control in See-Through Overtaking Assistance System2013In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 17, no 3, p. 612-615, article id 6423758Article in journal (Refereed)
    Abstract [en]

    In recently proposed cooperative overtaking assistance systems a video stream captured by a windshield-mounted camera in a vehicle is compressed and broadcast to the vehicle driving behind it, where it is displayed to the driver. It has been shown that this system can provide robust operation if video codec channel adaptation is undertaken by exploiting information from the cooperative awareness messages about any forthcoming increases in the multiple access channel load. In this letter we demonstrate the gains achievable in system performance when the video transmitter power control is also used. © 1997-2012 IEEE.

  • 265.
    Belyaev, Evgeny
    et al.
    Tampere University of Technology, Tempere, Finland.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Sjöberg, Katrin
    Volvo GTT, Göteborg, Sweden.
    Live video streaming in IEEE 802.11p vehicular networks: Demonstration of an automotive surveillance application2014In: Computer Communications Workshops (INFOCOM WKSHPS), 2014 IEEE Conference on, Piscataway, United States: IEEE Press, 2014, p. 131-132Conference paper (Refereed)
    Abstract [en]

    Prospective IEEE 802.11p-enabled automotive video applications are identified. Preliminary experimental results of inter-vehicular live video streaming for surveillance applications are presented. A test-bed for the demonstration of the achievable visual quality under different channel conditions is described.

  • 266.
    Belyaev, Evgeny
    et al.
    Tampere University of Technology, Tampere, Finland.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Surak, Adam
    Tampere University of Technology, Tampere, Finland.
    Gabbouj, Moncef
    Tampere University of Technology, Tampere, Finland.
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Egiazarian, Karen
    Tampere University of Technology, Tampere, Finland.
    Robust vehicle-to-infrastructure video transmission for road surveillance applications2015In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 64, no 7, p. 2991-3003Article in journal (Refereed)
    Abstract [en]

    IEEE 802.11p vehicle-to-vehicle and vehicle-to-infrastructure communication technology is currently an emerging research topic in both industry and academia. Respective spectrum allocation of 10 MHz channels in the 5.9 GHz band for USA and Europe allows considering inter-vehicle transmission of a live video information as a basis, which enables a new class of safety and infotainment automotive applications such as road video surveillance. This paper is first of its kind where such a video transmission system is developed and experimentally validated. We propose a low-complexity unequal packet loss protection and rate control algorithms for a scalable video coding based on the three-dimensional discrete wavelet transform. We show that in comparison with a scalable extension of the H.264/AVC standard the new codec is less sensitive to packet losses, has less computational complexity and provides comparable performance in case of unequal packet loss protection. It is specially designed to cope with severe channel fading typical for dynamic vehicular environments and has a low complexity, making it a feasible solution for real-time automotive surveillance applications. Extensive measurements obtained in realistic city traffic scenarios demonstrate that good visual quality and continuous playback is possible when the moving vehicle is in the radius of 600 meters from the roadside unit. ©2014 IEEE

  • 267.
    Ben Abdesslem, Fehmi
    et al.
    RISE - Research Institutes of Sweden, ICT, SICS.
    Abrahamsson, Henrik
    RISE - Research Institutes of Sweden, ICT, SICS.
    Ahlgren, Bengt
    RISE - Research Institutes of Sweden, ICT, SICS.
    Measuring Mobile Network Multi-Access for Time-Critical C-ITS Applications2018Conference paper (Refereed)
    Abstract [en]

    Cooperative Intelligent Transport Systems (C-ITS)make road traffic safer and more efficient, but require the mobilenetworks to handle time-critical applications. While some applicationsmay need new dedicated communications technologiessuch as IEEE 802.11p or 5G, other applications can use currentcellular networks. This study evaluates the performance that connectedvehicles can expect from existing networks, and estimatesthe potential gain of multi-access by simultaneously transmittingover several operators. We upload time-critical warning messagesfrom buses in Sweden, and characterise transaction times andnetwork availability. We conduct the experiments with differentprotocols: UDP, TCP, and HTTPS. Our results show that whenusing UDP, the median transaction time for sending a typicalwarning message is 135 ms. We also show that multi-access canbring this value down to 73 ms. For time-critical applicationsrequiring transaction times under 200 ms, multi-access canincrease availability of the network from to 57.4% to 92.0%.

  • 268.
    Ben Slimane, Slimane
    KTH, Superseded Departments, Signals, Sensors and Systems.
    A low complexity antenna diversity receiver for OFDM based systems2001In: IEEE International Conference on Communications, 2001, p. 1147-1151Conference paper (Refereed)
    Abstract [en]

    A low complexity antenna diversity architecture with a new combining technique suitable for orthogonal frequency division (OFDM) based systems is introduced in this paper. For a two branch antenna diversity, this structure requires only one FFT at the receiver and allows optimum maximum ratio combining. For systems with a higher number of antennas, the number of required FFTs when using such technique is reduced by half as compared to the conventional case where a different FFT is used for each receive antenna. As a result a considerable reduction in processing complexity is obtained especially for systems with high number of subcarriers. This method can also be seen as a way of increasing the number of antennas in OFDM transceivers without any major complexity increase. Thus, a considerable increase in diversity gain can be achieved

  • 269.
    Ben Slimane, Slimane
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Bounds on the Distribution of a Sum of Independent Lognormal Random Variables2001In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 49, no 6, p. 975-978Article in journal (Refereed)
    Abstract [en]

    The distribution function of a sum of lognormal random variables (RVs) appears in several communication problems. Approximations are usually used for such distribution as no closed form nor bounds exist. Bounds can be very useful in assessing the performance of any given system. In this letter, we derive upper and lower bounds on the distribution function of a sum of independent lognormal RVs. These bounds are given in a closed form and can be used in studying the performance of cellular radio and broadcasting systems.

  • 270.
    Ben Slimane, Slimane
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Channel estimation for HIPERLAN/2 with transmitter diversity2002Conference paper (Refereed)
  • 271.
    Ben Slimane, Slimane
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Channel estimation for HIPERLAN/2 with transmitter diversity2002In: 2002 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-5, CONFERENCE PROCEEDINGS, 2002, p. 26-30Conference paper (Refereed)
    Abstract [en]

    In this paper we propose a channel estimation technique for OFDM based systems, such as HIPERLAN/2 and IEEE 802.11a, with transmitter diversity. The proposed technique estimates all channel frequency responses, corresponding to each transmitter and receiver antenna pair, required for space-time processing In this OFDM based system. This technique is able to extract the channel state Information for two transmitter antennas using the same preamble as defined in the standard of HIPERLAN/2. The feasibility of this channel estimation method Is made possible by exploiting the structure of the OFDM modulation scheme. The results showed that the accuracy provided by this proposed method is comparable to that obtained when a single transmitter antenna is used.

  • 272.
    Ben Slimane, Slimane
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Channel estimation for OFDM based systems with transmitter diversity2002In: 2002 IEEE International Conference on Systems, Man and Cybernetics,, 2002, p. 397-402Conference paper (Refereed)
  • 273.
    Ben Slimane, Slimane
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Peak-to-average power ratio reduction of OFDM signals using broadband pulse shaping2002In: IEEE 56TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2002, VOLS 1-4, PROCEEDINGS, 2002, p. 889-893Conference paper (Refereed)
    Abstract [en]

    Orthogonal Frequency Division Multiplexing (OFDM) techniques allow the transmission of high data rates over broadband radio channels subject to multipath fading without the need for powerful channel equalization. However, they are very sensitive to nonlinear effects due to the high Peak-to-Average Power Ratio (PAPR) owned by the transmitted signal. This paper proposes an efficient technique for reducing the PAPR of OFDM signals. The proposed technique is very effective and flexible. The method avoids the use of extra Inverse Fast Fourier Transformations (IFFTs) as was done in some previously published techniques but instead is based on a proper selection of the time waveforms of the different sub-carriers of the OFDM modulation scheme. Thus, its implementation complexity is much low in comparison to the previous published methods. A closed form relation between the maximum PAPR and the used pulse shaping waveform is derived. The obtained results show that with broadband pulse shaping, the PAPR of OFDM modulated signals can be made very close to that of single carrier signals. The improved statistics of the PAPR in the transmitted signal is demonstrated through numerical results for some sets of time waveforms. The significant improvement in PAPR given by the present technique permits to reduce the complexity and cost of the transmitter significantly. In that, pulse shaping can be used not only to shape the spectrum of the transmitted signal but also to reduce its PAPR.

  • 274.
    Ben Slimane, Slimane
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Janssen, G.J.M.
    Delft University.
    Power optimization of M-PSK cochannel signals for a narrowband multiuser detector2001In: IEEE Pacific RIM Conference on Communications, Computers, and Signal Processing - Proceedings, 2001, p. 247-250Conference paper (Refereed)
    Abstract [en]

    An analytical method is presented to determine the optimum received power values for multiple cochannel multilevel phase-shift-keying (M-PSK) modulated signals. The aim is to achieve equal symbol error probability (SEP) for each of the signals when applying a narrowband multiuser detector based on successive cancellations. Power relations based on two approximations are derived and used to compute the average SEP for the different cochannel signals. The derived power relations are also compared against optimum power relations obtained through computer simulations

  • 275.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    A doubly stochastic Poisson model for self-similar traffic1995In: IEEE International Conference on Communications, 1995, p. 456-460Conference paper (Refereed)
    Abstract [en]

    This paper presents a data traffic model capable of describing the long-range dependence and self-similar burstiness structure found in measurement studies of packet data traffic. The model introduced is based on doubly stochastic Poisson processes. The intensity of arrivals is modeled as a continuous stochastic process. This process satisfies most of the properties found in the measurement studies, namely long-range dependence and self-similarity. The generality and simplicity of this model makes it attractive in data traffic modeling

  • 276.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Coded quadrature pulse-overlapping modulation techniques for personal communications1992In: 1st International Conference on Universal Personal Communications, 1992. ICUPC '92 Proceedings, 1992, p. 11-03/1-11-03/5Conference paper (Refereed)
    Abstract [en]

    Hard-limited quadrature pulse-overlapping modulation (QPOM) techniques have a constant envelope, good spectral properties and good performance especially in fading channels. These modulation techniques are suitable to applications using nonlinear or saturated power amplifiers to obtain high power and bandwidth efficiencies. A technique to combine convolutional codes and QPOM schemes to further improve its performance in fading channels is introduced and evaluated. At first, the QPOM scheme is decomposed into an encoder followed by a memoryless modulator. Then, the binary convolutional encoder is concatenated to the QPOM encoder and considered as one entity to be optimized. Performance of the coded QPOM scheme is analyzed and compared to uncoded QPOM and coded QPSK schemes

  • 277.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    IJF-OQPSK modulation schemes with MLSE receivers for portable/mobile communications1992Conference paper (Refereed)
    Abstract [en]

    A receiver structure for constant enveloped IJF-OQPSK modulation under fading channel conditions is introduced. Its performance in AWGN and Rayleigh fading channels was analyzed and verified by computer simulations. Results show the relation between the performance of the system and the memory introduced by the double-interval overlapping pulse shape. By properly using this memory, it is possible to achieve superior performance compared to conventional schemes. Even though no coding has been used, comparable results to coded schemes was obtained with no extra redundancy. Therefore, the complexity caused by multilevel modulation can be avoided, and transmission of signals with compact spectrum and good performance is possible. The constant envelope, compact spectrum, superior performance in fading channels and low complexity make the hardlimited IJF-OQPSK scheme a good choice for portable/mobile communications, to achieve low cost, small size, and high power and bandwidth efficiencies

  • 278.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Maximum likelihood sequence estimation of quadrature pulse-overlapping modulated signals for portable/mobile satellite1992In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 10, no 8Article in journal (Refereed)
  • 279.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Performance of 16-QAM signals on a fading mobile satellite channel1994In: AEU - International Journal of Electronics and Communications, ISSN 1434-8411, E-ISSN 1618-0399, Vol. 48, no 2, p. 68-75Article in journal (Refereed)
  • 280.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Performance of 16-QPOM signals on a fading mobile satellite channel1993In: Proceedings of the IEEE 1993 Pacific Rim Conference on Communications, Computers and Signal Processing, 1993, p. 674-677Conference paper (Refereed)
    Abstract [en]

    The authors present a maximum likelihood sequence estimation (MLSE) receiver structure for both linear and hard-limited 16-quadrature pulse overlapping modulation (QPOM) schemes. Using this structure, the performance of these schemes over shadowed Rician fading channels is studied. The structure of linear 16-QPOM schemes allowed the use of independent decoding for in-phase and quadrature components of the transmitted signal, thus reducing considerably the complexity of the MLSE receiver. The hard-limited 16-QPOM scheme used two hard-limited QPOM schemes in parallel. It is shown that an optimum MLSE receiver for this type of signal needs to consider both in-phase and quadrature components at the same time. Using the MLSE receiver, both schemes outperform conventional coherent 16-quadrature amplitude modulation (QAM)

  • 281.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Performance of 16-QPOM signals on a fading mobile satellite channel1993In: Proceedings of the IEEE Global Telecommunications Conference, IEEE , 1993, p. 1787-1791Conference paper (Refereed)
    Abstract [en]

    Presents the bit error probability of 16-QPOM schemes over mobile satellite shadowed Rician fading channels. An upper bound on the pairwise error probability is derived, and then combined with the transfer function bounding technique. The derived upper bound is given in a closed form without the need of any numerical integration. This upper bound is then used to evaluate the performance of both linear and hard-limited 16-QPOM signals. Simulation results are also performed to verify the analytical results

  • 282.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Performance of quadrature pulse-overlapping modulated signals in Rayleigh fading channels1991In: IEEE Global Telecommunications Conference and Exhibition, 1991, p. 1802-1806Conference paper (Refereed)
    Abstract [en]

    The authors discuss the average bit error probability of constant envelope quadrature pulse-overlapping modulation and maximum likelihood Viterbi decoding in a Rayleigh fading channel. The quadrature pulse-overlapping modulation is first decomposed into a linear encoder followed by a memoryless modulator. An upper bound on the average bit error probability as a function of the transfer function of the linear encoder is then developed under the assumption of using the Viterbi decoder with perfect fading amplitude measurement. Tightness of the bound was examined by means of computer simulation. A performance comparison with conventional quadrature phase shift keying is also provided

  • 283.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Quadrature Pulse-Overlapping Modulation Techniques1994In: Coded-Modulation Techniques for Fading Channels / [ed] S. Hamidreza Jamali, Tho Le-Ngoc, Kluwer Academic Publishers , 1994Chapter in book (Refereed)
  • 284.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Tight bounds on the error probability of coded modulation schemes in Rayleigh fading channels1994Conference paper (Refereed)
    Abstract [en]

    This paper presents a tight upper bound on the bit error performance of coded modulation schemes in Rayleigh fading channels. Upper and lower bounds on the pairwise error probability are first derived. The upper bound is then expressed in a product form to be used with the transfer function bounding technique. This upper bound has the same simplicity as the union-Chernoff bound while providing closer results to the exact expression. Examples for 4-state and 8-state TCM 8PSK schemes are also given to illustrate the tightness and the application of this upper bound

  • 285.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Concordia University.
    Tight Bounds on the Error Probability of Coded Modulation Schemes in Rayleigh Fading Channels1995In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 44, no 1, p. 121-130Article in journal (Refereed)
  • 286.
    Bengtsson, Hoai
    et al.
    Viktoria Swedish ICT, Gothenburg, Sweden.
    Chen, Lei
    Viktoria Swedish ICT, Gothenburg, Sweden.
    Voronov, Alexey
    Viktoria Swedish ICT, Gothenburg, Sweden.
    Englund, Cristofer
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research. Viktoria Swedish ICT, Gothenburg, Sweden.
    Interaction Protocol for Highway Platoon Merge2015In: 2015 IEEE 18th International Conference on Intelligent Transportation Systems / [ed] Lisa O’Conner, Los Alamitos: IEEE, 2015, p. 1971-1976, article id 7313411Conference paper (Refereed)
    Abstract [en]

    An interaction protocol for cooperative platoon merge on highways is proposed. The interaction protocol facilitates a challenge scenario for the Grand Cooperative Driving Challenge (GCDC) 2016, where two platoons running on separate lanes merge into one platoon due to a roadwork in one of the lanes. Detailed interaction procedures, described with state machines of each vehicle are presented. A communication message set is designed to support platoon controllers to perform safe and efficient manoeuvres. © 2015 IEEE.

  • 287. Bengtsson, Hoai
    et al.
    Chen, Lei
    Voronov, Alexey
    Englund, Cristofer
    RISE, Swedish ICT, Viktoria.
    Interaction Protocol for Highway Platoon Merge2015In: Intelligent Transportation Systems (ITSC), 2015 IEEE 18th International Conference on, 2015Conference paper (Refereed)
  • 288.
    Bennani, Zakaria
    KTH, Superseded Departments, Teleinformatics.
    Quality of Service Support for Wireless LANs2000Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As the research and development of mobile computing is becoming increasingly interesting and important to corporations and private users, great efforts are being made to ensure that the wireless network technology is being developed to match the performance level showed by wired network technologies. Introducing wireless mobile computing into already existing and operational situations, that have up to date been taken care of with wired technology, should not mean a degradation of the existing performance level. In other words, there should not be any decrease in the quality of service experienced by the end users due to the mobility or wireless factor.

    When developing quality of service support mechanisms that use characteristics specific to the Internet Protocol, considerations have to be made to make certain that the solutions and implementations developed will be deployable with the next generation Internet Protocol, IPv6. Since the ever decreasing address space in IPv4 is becoming more and more of a problem, at some point migration to IPv6 has to be made. Therefore, this thesis will base its developments on the use of IPv6.

    The thesis concerns the problem of providing statistical QoS guarantees for multimedia applications running over a wireless LAN such as WaveLAN. Using the DiffServ model and support of IPv6, we develop mechanisms for managing QoS and mobility. With the use of pre-connection schemes and a domain routing approach, Mobile Node mobility and Handoffs are handled in such a way to diminish latencies that occur when in-LAN and cross-LAN handoffs are made. To handle QoS guarantees, a bandwidth broker placed in the Access Points manages bandwidth allocations for different cells and configures the traffic parameters of each mobile so that the usage of the wireless MAC layer is controlled. The border router is connected via ATM to core routers in several places in France. Experimentation on the platform involves a DIS application (Distributed Interactive Simulation) running at different sites.

    The development work is done on FreeBSD systems in C.

  • 289.
    Bennehag, David
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Wulcan, Alexander
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Claesson, ommy
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Förstudie till ett stadstäckande och öppet WiFi i Trollhättan2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Förstudien behandlar den tekniska delen av ett teoretiskt stadstäckande öppet WiFi i Trollhättan, Sverige. Trollhättans kommun beställde en förstudie från Högskolan Väst som skulle agera beslutsunderlag till hur de skulle ta ärendet vidare. Studien är begränsad till den tekniska biten, där bland annat val av utrustning, trådlösa tekniker och riskanalys av nätverket ingår. Arbetet varit väldigt teoretiskt inriktat med en metod som till största del består utav att samla information och kunskaper från vetenskapliga rapporter, teknikorienterade hemsidor och andra relaterade arbeten.De trådlösa standarder som jämfördes teoretiskt i förstudien var 802.11g och 802.11n. 802.11n valdes som den standarden som bäst passade just detta nätverk, främst för dess positiva egenskaper när det gäller täckning, hastighet och bakåtkompatibilitet. 802.11n seräven ut att garantera en säker framtid när det gäller implementering i mobila enheter. Föreslaget på utrustning består av två olika accesspunkter, antingen 2602e eller 3602e beroende på den slutgiltiga budgeten. Dessa produkter är från Cisco och klarade olikastresstester med bra resultat samtidigt som de stödde den föreslagna standarden 802.11n. WLAN controllern (Ciscos 5500-serie) som valdes ut stödjer det krav på antal accesspunkter som bestämts, samtidigt som den lämpar sig bra för eventuella framtidakrav. Routern till detta nätverk är en Cisco 891-router. Anledningen till att denna router valdes var för att den har 4 portar som kan ge ström över Ethernet till accesspunkterna. Säkerhetsanalysen gjordes med hjälp utav CORAS-metoden där det diskuteras vilka riskernätverket kan ställas inför och vad dessa risker kan få för konsekvenser. Försök till att hitta lösningar som var direkt applicerbara på det stadstäckande öppna nätverket gjordes även.Förstudien avslutas med en kostnadsberäkning av nätverket, baserad på andras tidigare arbeten och deras kostnader, speciellt från Jönköping, Helsingborg och Mountain View.

  • 290.
    Bentahar, Younes
    KTH, School of Information and Communication Technology (ICT).
    DNS prestanda2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Use of computers and computer networks is nowadays a part of everyday life. You do not use them only at home when you sit at you computer, but you can use them all the time everywhere. This can involve everything from surf to any website when you are at home, to checking your email on your mobile when you are on your way to work. Most people do not think about how it really works when they try to access a web page by typing the address into their browser, but something that most people probably notice is how long it can sometimes take to access a web page.

    All items which are directly connected to the IP network have a unique IP address that is used to make it possible to communicate. The IP address is either a period separated sequence of digits representing 32 bits or a colon separated sequence of digits representing 128 bits, depending on whether the address is an IPv4 or IPv6 address. Such numeric sequences are often difficult for us humans to remember therefore, the domain name system (DNS) was constructed. DNS makes it possible for us to write addresses in a textual format to access an item stored in a device connected to the network. DNS can be seen as a directory for the network and can be compared to a telephone directory, where if you know the name of a person can find his or her phone number.

    This thesis will describe how the various address translations are done by using DNS. It will also examine how much impact DNS has on the experienced delay from the time you type a web page address in the address bar of your browser to the actual time you reach the website. A survey of DNS performance will be presented to investigate how much delay can be reduced by using one of Sweden's two most well-known public DNS servers (Google Public DNS and OpenDNS) instead of the normal default DNS server provided by one's Internet service provider (ISP).

    The survey will also show how the DNS lookup waiting time changes at different times of day and different days of the week. The purpose of this work is to provide a basic explanation of what DNS is and increase the understanding of how an everyday user in a simple way can make their network usage more effective by getting their DNS lookups to occur faster.

    The conclusion from this thesis is that the alternative DNS server, Google Public DNS has the fastest DNS lookup time for this particular computer which the measurement was carried on. But this tells us nothing about whether the case for any other network users because the observed DNS performance has a large extent dependent on the ISP you are connected to, and what place you are at.

  • 291.
    Bentes, João
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Khandelwal, Siddhartha
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Carlsson, Hampus
    Halmstad University, School of Information Technology.
    Kärrman, Marcus
    Halmstad University, School of Information Technology.
    Svensson, Tim
    Halmstad University, School of Information Technology.
    Wickström, Nicholas
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), CAISR - Center for Applied Intelligent Systems Research.
    Novel System Architecture for Online Gait Analysis2017Conference paper (Refereed)
    Abstract [en]

    Although wearable devices can be used to perform continuous gait analysis in daily life, existing platforms only support short-term analysis in quasi-controlled environments. This paper proposes a novel system architecture that is designed for long-term, online gait analysis in free-living environments. Various aspects related to the feasibility and scalability of the proposed system are presented.

  • 292. Bentley, Frank
    et al.
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Designing From Data: A Case Study From the Health Mashups Service2013In: Workshop on Informing Future Design via Large-Scale Research Methods and Big Data, 2013Conference paper (Refereed)
    Abstract [en]

    Instrumentation of mobile service interactions now allows for the ability to understand use in new ways and to base the design of system iterations as well as future services on data obtained from use “in the wild”over extended periods of time. This position paper will detail a few specific instances in the Health Mashupsproject where we were able to use usage data to improve the design and to create design implications to increase engagement in new services.

  • 293. Bentley, Frank
    et al.
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Stephenson, Peter
    Levy, Laura
    Jones, Brian
    Robertson, Scott
    Price, Ed
    Catrambone, Richard
    Wilson, Jeff
    Health Mashups: Presenting Statistical Patterns between Wellbeing Data and Context in Natural Language to Promote Behavior Change2013In: ACM Transactions on Computer-Human Interaction, ISSN 1073-0516, E-ISSN 1557-7325, Vol. 20, no 5, p. 30-Article in journal (Refereed)
    Abstract [en]

    People now have access to many sources of data about their health and wellbeing. Yet, most people cannot wade through all of this data to answer basic questions about their long-term wellbeing: Do I gain weight when I have busy days? Do I walk more when I work in the city? Do I sleep better on nights after I work out? We built the Health Mashups system to identify connections that are significant over time between weight, sleep, step count, calendar data, location, weather, pain, food intake, and mood. These significant observations are displayed in a mobile application using natural language, for example, "You are happier on days when you sleep more." We performed a pilot study, made improvements to the system, and then conducted a 90-day trial with 60 diverse participants, learning that interactions between wellbeing and context are highly individual and that our system supported an increased self-understanding that lead to focused behavior changes.

  • 294.
    Berbineau, Marion
    et al.
    IFSTTAR, Villeneuve d’Ascq, France.
    Jonsson, MagnusHalmstad University, School of Information Science, Computer and Electrical Engineering (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).Bonnin, Jean-MarieTelecom Bretagne, Cesson Sévigné, France.Cherkaoui, SoumayaUniversité de Sherbrooke, Canada.Aguado, MarinaUniversity of the Basque Country, Bilbao, Spain.Rico Garcia, CristinaDLR, German Aerospace Center, Oberpfaffenhofen-Wessling, Germany.Ghannoum, HassanSNCF, Paris, France.Mehmood, RashidUniversity of Huddersfield, UK.Vinel, AlexeyTampere University of Technology, Finland.
    Communication Technologies for Vehicles: 5th International Workshop, Nets4Cars/Nets4Trains 2013, Villeneuve d' Ascq, France, May 14-15, 2013, Proceedings2013Conference proceedings (editor) (Refereed)
  • 295. Berg, Jacob
    et al.
    Landin, Niclas
    Kommunikationskort2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Raytelligence har utvecklat en radar som kan registrera rörelse och hjärtfrekvens hos människor. Datan från radarn skickas över Universal Serial Bus (USB) till en extern dator. För att produkten ska bli mer användarvänlig krävs en bättre kommunikationslösning. Projektet går ut på att implementera en trådlös kommunikation i form av bluetooth och Wireless Local Area Network (WLAN) som kan skicka datan från radarn trådlöst till en extern dator eller mobil enhet. I rapporten beskrivs de olika metoderna som använts för att åstadkomma den trådlösa kommunikationen. Det beskrivs passande gränssnitt, val av passande kommunikationsmodul, implementering och kalibrering av antenn, val av komponenter och olika sätt att motverka Elektromagnetisk Interferens (EMI) för att få bra förutsättningar för en Elektromagnetisk kompatibilitet (EMC)-certifiering. Resultatet av projektet är en produkt som bygger på kommunikationsmodulen RS9113 och Raytelligence radarkort.

  • 296.
    Bergblomma, Marcus
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Martin
    Mälardalen University, School of Innovation, Design and Engineering.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Gerdtman, Christer
    Motion Control AB, Västerås, Sweden .
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    A wireless low latency control system for harsh environments2012In: IFAC Proceedings Volumes (IFAC-PapersOnline): Vol. 11, PART 1, 2012, p. 17-22Conference paper (Refereed)
    Abstract [en]

    The use of wireless communication technologies in the industry offer severaladvantages. One advantage is the ability to deploy sensors where they previously could noteasily be deployed, for instance on parts that rotate. To use wireless communication in industrialcontrol loops, demands on reliability and latency requirements has to be met. This in anenvironment that may be harsh for radio communication. This work presents a reliable, lowlatency wireless communication system. The system is used in a wireless thyristor control loopin a hydro power plant generator. The wireless communication is based on Bluetooth radiomodules. The work shows a latency analysis together with empirical hardware based latencyand packet error rate measurements. The background noise of a hydro power plant station isalso investigated. The average latency between the Bluetooth modules for the proposed systemis 5.09 ms. The packet error rate is 0.00288 for the wireless low latency control system deployedin a hydro power plant.

  • 297. Berger, Andre
    et al.
    Gross, James
    RWTH Aachen University, Germany.
    Harks, Tobias
    The k–Constrained Bipartite Matching Problem: Approximation Algorithms and Applications to Wireless Networks2010In: Proceedings IEEE INFOCOM, 2010, IEEE conference proceedings, 2010, p. 1-9Conference paper (Refereed)
    Abstract [en]

    In communication networks, resource assignment problems appear in several different settings. These problems are often modeled by a maximum weight matching problem in bipartite graphs and efficient matching algorithms are well known. In several applications, the corresponding matching problem has to be solved many times in a row as the underlying system operates in a time-slotted fashion and the edge weights change over time. However, changing the assignments can come with a certain cost for reconfiguration that depends on the number of changed edges between subsequent assignments. In order to control the cost of reconfiguration, we propose the k-constrained bipartite matching problem for bipartite graphs, which seeks an optimal matching that realizes at most k changes from a previous matching. We provide fast approximation algorithms with provable guarantees for this problem. Furthermore, to cope with the sequential nature of assignment problems, we introduce an online variant of the k-constrained matching problem and derive online algorithms that are based on our approximation algorithms for the k-constrained bipartite matching problem. Finally, we establish the applicability of our model and our algorithms in the context of OFDMA wireless networks finding a significant performance improvement for the proposed algorithms.

  • 298.
    Berggren, Anders
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Borg, Martin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    A Comparative Study ofTwo Multicast Routing Algorithms2002Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master Thesis examines several aspects of two different multicast forwarding algorithms. The scaling properties of the currently used algorithms were examined under different criteria, such as delay, traffic concentration, and size of the routing tables.

    Many new Internet applications, such as videoconferencing, resource discovery, Internet radio and online games, depend on a network support for efficient point-to-multipoint communication. Sending identical data to a group of receivers using a series of unicast transmissions obviously has massive scaling problems. Multicasting provides an efficient and elegant solution that significantly reduces the total bandwidth demand as well as the load on both senders and intermediate routers.

    In this report we study two multicast routing algorithms, source based trees (SBT) and core based trees (CBT). SBT builds one delivery tree per source and group by flooding the initial packet through the entire network, and then removing the links that do not lead to group members (“pruning”). To be able to discover new members, flooding must occur periodically. CBT on the other hand, builds one delivery tree per group, shared by all sources. There is one core router per group and members must explicitly join the delivery tree by notifying the core. Off-tree sources must tunnel their traffic to the core for distribution along the tree.

    SBT has two main drawbacks. Firstly, the maintenance of the delivery tree requires periodic flooding of the network. Furthermore, SBT routers must keep state that grows as the product of the number of sources and the number of groups. CBT solves both of these scaling problems, but the shared tree will often lead to sub-optimal paths and increased delay. The traffic may also be concentrated on fewer links than in SBT.

    We compared the characteristics of the SBT and CBT algorithms in different network topologies using a simulation program. Since existing network simulation tools were found to be poor when it came to multicasting, we decided to develop a new network generator and simulator tool with multicasting aspects in focus. We also developed a tool to visualize the networks generated by the simulator and monitor the traffic. The report presents many simulation results that illustrate the significance of different trade-offs between SBT and CBT. Performance characteristics such as delay, join latency, tree size, total traffic and traffic concentration are analysed and examined.

    The conclusion is that each protocol can be preferable in certain scenarios, depending on how important the different parameters are. CBT always performs better than SBT for single source applications if the core can be placed at the sender’s local router. However, this core placement is not necessarily optimal for CBT. The situation is more complex in groups with several sources. There is a trade-off between the scaling problems of SBT and the increased delay and traffic concentration of CBT.

  • 299.
    Berggren, Fredrik
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Communication Systems, CoS (closed 2012-01-01).
    Capacity analysis for noncooperative interference environments2005In: VTC 2005-Spring: 2005 IEEE 61st Vehicular Technology Conference, Proceedings, IEEE , 2005, no 3, p. 1479-1483Conference paper (Refereed)
    Abstract [en]

    To enhance the wireless bandwidth utilization, new forms of innovative spectrum policies, dynamically sharing channels over time and space, have been discussed. Dynamic spectrum access lets systems share the spectrum, to achieve better band-width utilization and trunking gains. In this work, we consider a case where such access is performed in an uncoordinated fashion. The paradigm shift to open frequency bands implies a need to investigate and verify resulting capacity gains. Herein, we give a general method for evaluating system capacity subject to outage probability constraints over fading channels, in an unlicensed band environment with uncoordinated systems. The channel fading effects include both attenuation, shadowing and multipath propagation and we end up with expressions, which are solved by numerical integration. The spectrum sharing is here performed by means of autonomous dynamic channel allocation (DCA), and we compare two DCA methods, maximum SIR DCA and random DCA.

  • 300.
    Berggren, Magnus
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Simon, Daniel
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nilsson, D
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Dyreklev, P
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Norberg, P
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Nordlinder, S
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Ersman, PA
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Gustafsson, G
    Acreo Swedish ICT, Box 787, SE-601 17, Norrköping, Sweden..
    Wikner, Jacob
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, Faculty of Science & Engineering.
    Hederén, J
    DU Radio, Ericsson AB, SE-583 30, Linköping, Sweden..
    Hentzell, H
    Swedish ICT Research, Box 1151, SE-164 26, Kista, Sweden..
    Browsing the Real World using Organic Electronics, Si-Chips, and a Human Touch.2016In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, no 10, p. 1911-1916Article in journal (Refereed)
    Abstract [en]

    Organic electronics have been developed according to an orthodox doctrine advocating "all-printed, "all-organic and "ultra-low-cost primarily targeting various e-paper applications. In order to harvest from the great opportunities afforded with organic electronics potentially operating as communication and sensor outposts within existing and future complex communication infrastructures, high-quality computing and communication protocols must be integrated with the organic electronics. Here, we debate and scrutinize the twinning of the signal-processing capability of traditional integrated silicon chips with organic electronics and sensors, and to use our body as a natural local network with our bare hand as the browser of the physical world. The resulting platform provides a body network, i.e., a personalized web, composed of e-label sensors, bioelectronics, and mobile devices that together make it possible to monitor and record both our ambience and health-status parameters, supported by the ubiquitous mobile network and the resources of the "cloud".

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