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  • 3501. Yoo, S. J. B.
    et al.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    InP photonic integrated circuits for optical communciations2008Conference paper (Refereed)
    Abstract [en]

    This paper describes photonic integration circuits (PICs) realized on the InP platform including high-speed mode locked lasers, arrayed waveguide gratings (AWGs), differential Mach-Zehnder optical switches (MZI), and high-speed amplitude and phase modulators. Selected area hydride vapor phase epitaxy (HVPE) and organometallic chemical vapor deposition (OMCVD) were used to realized planarized and passivated integration including active and passive elements. The integrated chips of various configurations were investigated for 'Optical Code Division Multiple Access (O-CDMA)', in local area networks, and for 'Optical Arbitrary Waveform Generation (OAWG),' in high-speed otptical communications.

  • 3502.
    You, Lei
    et al.
    Qingdao University, Peoples R China.
    Lei, Lei
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. University of Maryland, MD USA.
    A Performance Study of Energy Minimization for Interleaved and Localized FDMA2014In: 2014 IEEE 19TH INTERNATIONAL WORKSHOP ON COMPUTER AIDED MODELING AND DESIGN OF COMMUNICATION LINKS AND NETWORKS (CAMAD), IEEE , 2014, p. 16-20Conference paper (Refereed)
    Abstract [en]

    Optimal channel allocation is a key performance engineering aspect in single-carrier frequency-division multiple access (SC-FDMA). It is of significance to consider minimum sum power (Min-Power), subject to meeting specified users demand, since mobile users typically employ battery-powered handsets. In this paper, we prove that Min-Power is polynomial-time solvable for interleaved SC-FDMA (IFDMA). Then we propose a channel allocation algorithm for IFDMA, which is guaranteed to achieve global optimum in polynomial time. We numerically compare the proposed algorithm with optimal localized SC-FDMA (LFDMA) for Min-Power. The results show that LFDMA outperforms IFDMA in the maximal supported user demand. When the user demand can be satisfied in both LFDMA and IFDMA, LFDMA performs slightly better than IFDMA. However MinPower is polynomial-time solvable for IFDMA whereas it is not for LFDMA.

  • 3503.
    You, Lei
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Lei, Lei
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. University of Maryland, MD 20740 USA.
    Optimizing Power and User Association for Energy Saving in Load-Coupled Cooperative LTE2016In: 2016 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), IEEE , 2016Conference paper (Refereed)
    Abstract [en]

    We consider an energy minimization problem for cooperative LTE networks. To reduce energy consumption, we investigate how to jointly optimize the transmit power and the association between cells and user equipments (UEs), by taking into consideration joint transmission (JT), one of the coordinated multipoint (CoMP) techniques. We formulate the optimization problem mathematically. For solving the problem, a dynamic power allocation algorithm that adjusts the transmit power of all cells, and an algorithm for optimizing the cell-UE association, are proposed. The two algorithms are iteratively used in an algorithmic framework to enhance the energy performance. Numerically, the proposed algorithms can lead to lower energy consumption than the optimal energy setting in the non-JT case. In comparison to fixed power allocation in JT, the proposed dynamic power allocation algorithm is able to significantly reduce the energy consumption.

  • 3504.
    You, Lei
    et al.
    Uppsala University, Sweden.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Uppsala University, Sweden.
    Joint CoMP-Cell Selection and Resource Allocation in Fronthaul-Constrained C-RAN2017In: 2017 15TH INTERNATIONAL SYMPOSIUM ON MODELING AND OPTIMIZATION IN MOBILE, AD HOC, AND WIRELESS NETWORKS (WIOPT), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Cloud-based Radio Access Network (C-RAN) is a promising architecture for future cellular networks, in which Baseband Units (BBUs) are placed at a centralized location, with capacity-constrained fronthaul connected to multiple distributed Remote Radio Heads (RRHs) that are far away from the BBUs. The centralization of signal processing enables the flexibility for coordinated multi-point transmission (CoMP) to meet high traffic demand of users. We investigate how to jointly optimize CoMP-cell selection and base station resource allocation so as to enhance the quality of service (QoS), subject to the fronthaul capacity constraint in orthogonal frequency-division multiple access (OFDMA) based C-RAN. The problem is proved to be NP-hard in this paper. To deal with the computational complexity, we derive a partial optimality condition as the foundation for designing a cell-selection algorithm. Besides, we provide a solution method of the optimum of the time-frequency resource allocation problem without loss of fairness on the QoS enhancement of all users. The simulations show good performance of the proposed algorithms for jointly optimizing the cell selection and resource allocation in a C-RAN, with respect to QoS.

  • 3505.
    You, Lei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Yuan, Di
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Lei, Lei
    Sun, Sumei
    Chatzinotas, Symeon
    Ottersten, Björn
    Resource optimization with load coupling in multi-cell NOMA2018In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 7, p. 4735-4749Article in journal (Refereed)
  • 3506.
    Yu, Kan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    On Reliable and Deadline-Constrained Communication in Wireless Industrial Networks2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Along with the quick development of wireless communication technologies, industrial automation networks are also in unceasing evolution. Industrial wireless sensor and actuator networks (IWSAN) have been increasingly adopted in industrial automation systems. Although there are a number of advantages of replacing cables with wireless links, such as cost reduction, enhanced scalability and flexibility, the stringent requirements on communication reliability and meeting firm deadlines from industrial mission-critical applications must still be fulfilled. Also, transmissions over wireless channels in industrial environments are prone to noise and interferences, resulting in frequent erroneous packet deliveries. Although industrial automation systems are usually designed to be tolerant of certain communication errors, successive transmission failures may still cause downtime of industrial applications, which might lead to significant economic losses or even serious accidents. This thesis addresses the problems mentioned above and aims to provide reliable and deadline-constrained communication via IWSANs for industrial automation systems. On the MAC layer, existing IWSAN standards utilize automatic repeat request (ARQ) to improve reliability at the cost of additional transmission latency. An alternative method is to use Forward Error Correction (FEC) schemes to provide reliable communication by recovering erroneous data and avoiding unnecessary retransmissions. On the MAC layer, Time Division Multiple Access (TDMA) is usually applied in current IWSAN standards for collision-free and deterministic communication. An inappropriate scheduling scheme may introduce high transmission jitter and degrade the quality of control. On the network layer, routing protocols play an important role in both communication reliability and latency. Existing solutions are either hardly able to fulfill all stringent requirements from the mission-critical industrial applications, too complicated to be realized, or lack verification in reality. The contributions of this thesis consist of (i) the possibilities of using FEC schemes in IWSANs is explored under the requirements of existing standards on the MAC layer. A compatible and flexible FEC scheme on the MAC layer for IWSANs that does not violate the standard is proposed and evaluated by simulations. (ii) To guarantee an acceptable control quality, a TDMA scheduling scheme is presented aiming for low communication jitter, and it is compared to classic scheduling schemes. (iii) The advantages of exploiting flooding in IWSANs is discussed; a reliable controlled flooding-based routing protocol is proposed and compared to both traditional routing protocols and other flooding-based protocols. (iv) A complete IWSAN platform is built and the whole protocol stack is implemented. Measurements were conducted in a real industrial environment to verify the correctness of the proposed solution.

  • 3507.
    Yu, Kan
    Mälardalen University, School of Innovation, Design and Engineering.
    On Reliable Real Time Communication in Industrial Wireless Sensor Networks2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the industrial automation, Industrial Wireless Sensor Networks (IWSNs) have been increasingly applied due to a great number of benefits such as convenient installation, flexible deployment and cost efficiency. Compared with conventional wireless systems, IWSNs have more stringent requirements communication reliability and real time performance. However, IWSNs are frequently deployed in a hash industrial environment with electromagnetic disturbances, moving objects and non-line-of-sight (NLOS) communication. Because of the vulnerability of wireless signal, IWSNs are under high risk oftransmission failures, which may result in missing or delaying of process orcontrol data. For industrial automation, missing the process or control deadlineis intolerable, which may terminate industrial application and finally result in economic loss and safety problems. From hierarchy point of view, the high communication reliability and low communication latency can be achieved from different network layers. OnMAC layer, existing protocols in IWSNs only provide automatic repeat request (ARQ) to improve reliability at the cost of real time performance. Analternative method is to apply Forward Error Correction (FEC) mechanism on MAC layer to provide more reliable transmissions and reduce acknowledgement messages by recovering error data. On network layer, routing protocolplays an important role in both communication reliability and latency. Traditionalrouting protocols in IWSNs are either hardly able to fulfill both of these requirements or overcomplicated.In this thesis, we initially explore the possibilities of introducing FEC intoIWSN under the requirements of the existing standard on MAC layer. Then we propose compatible and flexible FEC schemes on MAC layer for IWSNs without violating the standard format. Routing protocols based on flooding are proved to increase the Packet Delivery Ratio (PDR) by transmission diversity.We propose reliable and robust routing protocols with respect to high reliability and real time performance for IWSNs.

  • 3508.
    Yu, Kan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Barac, Filip
    Mid Sweden University.
    Gidlund, Mikael
    ABB, Corporate Research.
    Åkerberg, Johan
    ABB, Corporate Research.
    Adaptive Forward Error Correction for Best Effort Wireless Sensor Networks2012In: 2012 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), 2012, p. 7104-7109Conference paper (Refereed)
    Abstract [en]

    In this work we propose an Adaptive Forward Error Correction (AFEC) algorithm for best effort Wireless Sensor Networks. The switching model is described in terms of a finite-state Markov model and it is based on the channel behavior,observed via Packet Delivery Ratio in the recent past. We compare the performance of AFEC with static FEC, as well as uncoded transmissions. The results demonstrate a gain in PDR achieved by introducing FEC coding in uncoded IEEE 802.15.4 transmissions, as well as the advantages over static FEC schemes,namely increased throughput and reduced energy consumption.The proposed solution is IEEE 802.15.4-compliant and requires no additional feedback channels.

  • 3509.
    Yu, Kan
    et al.
    Mälardalen University.
    Barac, Filip
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Gidlund, Mikael
    ABB AB, Corporate Research, Sweden.
    Åkerberg, Johan
    ABB AB, Corporate Research, Sweden.
    Björkman, Mats
    Mälardalen University, Sweden.
    A Flexible Error Correction Scheme for IEEE 802.15.4-based Industrial Wireless Sensor Networks2012In: IEEE International Symposium on Industrial Electronics, IEEE conference proceedings, 2012, p. 1172-1177Conference paper (Refereed)
    Abstract [en]

    Noise and interference make a substantial impacton wireless transmissions in industrial environments, resulting infrequent erroneous packet deliveries. Existing industrial communicationstandards adopt the IEEE 802.15.4 specification, whichprovides no means to correct the detected errors. We proposean IEEE 802.15.4-compliant Forward Error Correction-basedapproach that can be easily retrofitted into the standard withoutthe need for any kind of interaction with chip manufacturers orstandardization bodies. We evaluate the approach on link- andnetwork-level scenarios. Improvement of reliability by using FECcan yield multiple benefits: a reduced number of retransmissions,and lower average latency, to name a few. With respect to theuncoded system, the proposed solution provides identical codinggain as the traditional FEC method, at a significantly lowercomputational load of decoding

  • 3510.
    Yu, Kan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Filip, Barac
    Mid Sweden University.
    Mikael, Gidlund
    ABB, Corporate Research.
    Åkerberg, Johan
    ABB, Corporate Research.
    Mats, Björkman
    Mälardalen University, School of Innovation, Design and Engineering.
    A Flexible Error Correction Scheme for IEEE 802.15.4-based Industrial Wireless Sensor Networks2012In: IEEE International Symposium on Industrial Electronics, 2012, p. 1172-1177Conference paper (Refereed)
    Abstract [en]

    Noise and interference make a substantial impacton wireless transmissions in industrial environments, resulting infrequent erroneous packet deliveries. Existing industrial communication standards adopt the IEEE 802.15.4 specification, which provides no means to correct the detected errors. We propose an IEEE 802.15.4-compliant Forward Error Correction-basedapproach that can be easily retrofitted into the standard withoutthe need for any kind of interaction with chip manufacturers orstandardization bodies. We evaluate the approach on link- and network-level scenarios. Improvement of reliability by using FEC can yield multiple benefits: a reduced number of retransmissions,and lower average latency, to name a few. With respect to the uncoded system, the proposed solution provides identical codinggain as the traditional FEC method, at a significantly lower computational load of decoding.

  • 3511.
    Yu, Kan
    et al.
    Mälardalens Högskola.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Åkerberg, Johan
    ABB Corporate Research.
    Björkman, Mats
    Mälardalens Högskola.
    Low Jitter Scheduling for Industrial Wireless Sensor and Actuator Networks2013Conference paper (Refereed)
  • 3512.
    Yu, Kan
    et al.
    Mälardalen University.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Systems and Technology.
    Åkerberg, Johan
    ABB Corporate Research, Sweden.
    Björkman, Mats
    Mälardalen University, Sweden.
    Performance Evaluations and Measurements of the REALFLOW Routing Protocol in Wireless Industrial Networks2017In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 13, no 3, p. 1410-1420, article id 7506102Article in journal (Refereed)
    Abstract [en]

    Industrial wireless sensor and actuator networks (IWSANs) offer significant advantages to industria lautomation. However, high-reliability demands and hard communication deadlines pose challenges to its practical applications. To achieve this goal, flooding is considered as a promising approach due to multipath diversity and simplicity. In this paper, an enhanced version of REALFLOW, a flooding-based routing protocol for IWSANs is presented. Compared to the original REALFLOW, network management and network stability are improved. REALFLOW is compared with four other flooding protocols via simulations. The simulation results show that REALFLOW has better performance in terms of reliability and consecutive transmission errors when considering deadlines. Compared with normal flooding, REALFLOW achieves comparable reliability performance with decreased redundancy. Measurements from a prototype implementation conducted in an industrial manufacturing workshop reveal that high-reliability and low-application failure rates can be achieved, giving more confidence in providing reliable wireless sensing and actuating for industrial automation.

  • 3513.
    Yu, Kan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Gidlund, Mikael
    ABB, Corporate Research.
    Åkerberg, Johan
    ABB, Corporate Research.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Reliable and Low Latency Transmission in Industrial Wireless Sensor Networks2011In: Procedia Computer Science, ISSN 1877-0509, E-ISSN 1877-0509, Vol. 5, p. 866-873Article in journal (Refereed)
    Abstract [en]

    The major advantages with Industrial Wireless Sensor Networks (IWSNs) in process automation are cable cost reduction, enhanced flexibility and enabling new emerging applications such as wireless control. However, transmission over the wireless channel is prone to noise and interference which causes packets to be erroneous received at the receiver node. To improve the link reliability in lossy channels, error correcting codes are commonly used. In this paper we discuss the use of forward error correction (FEC) codes in IWSN in order not only to improve the link reliability but also to reduce the number of retransmissions in harsh industrial environments. We propose a FEC scheme suitable for MAC level protection where the packet is divided into groups and encoded using systematic FEC codes. We have implemented different FEC codes in a typical IWSN chip to evaluate memory consumption and to ensure that we are not violating the strict timing rules for acknowledgment. Our results show that some FEC codes are suitable to be implemented in a typical IWSN node while several fails due to large memory footprint or to long encoding and decoding time.

  • 3514.
    Yu, Kan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Gidlund, Mikael
    ABB, Corporate Research.
    Åkerberg, Johan
    ABB, Corporate Research.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Reliable RSS-based Routing Protocol for Industrial Wireless Sensor Networks2012In: IECON 2012 - 38th Annual Conference on IEEE Industrial Electronics Society: Proceeding, 2012, p. 3231-3237Conference paper (Refereed)
    Abstract [en]

    High reliability and real-time performance are main research challenges in Industrial Wireless Sensor Networks (IWSNs). Existing routing protocols applied in IWSNs are either overcomplicated or fail to fulfill the stringent requirements. In this paper, we propose a reliable and flexible Received Signal Strength-based routing scheme. Our proposed solution can achieve a seamless transition in the event of topology change and can be applied in different industrial environments. The simulation results show that our solution outperforms conventional routing protocols in both reliability and latency. Furthermore, the result also proves that the changes of the network topology have no impact on data transmissions of other nodes by our scheme, whereas conventional routing protocols are shown to fail to recover the network in a short time. Finally, due to dynamic weighting mechanism, the proposed scheme is verified to achieve significantly higher reliability in scenarios with obstacles and avoid installation troubles, compared to location-based flooding scheme. Thus, our proposed scheme is considered to be more suitable for IWSNs than other routing protocols.

  • 3515.
    Yu, Kan
    et al.
    Mälardalens Högskola.
    Zheng, Tao
    Beijing Jiatong University.
    Pang, Zhibo
    ABB Corporate Research.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Åkerberg, Johan
    ABB Corporate Research.
    Björkman, Mats
    Mälardalens Högskola.
    Reliable Flooding-based Downlink Transmissions for Industrial Wireless Sensor and Actuator Networks2013Conference paper (Refereed)
  • 3516.
    Yu, Kan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Åkerberg, Johan
    Corp Res, ABB AB, Sweden.
    Gidlund, Mikael
    Corp Res, ABB AB, Sweden.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Performance Evaluation and Measurement of REALFLOW Routing Protocol in WirelessIndustrial NetworksIn: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050Article in journal (Refereed)
    Abstract [en]

    Industrial Wireless Sensor and Actuator Networks(IWSAN) offer significant advantages to industrial automationsystems. Requirements on reliability are highly demanding formany industrial applications. Due to multipath diversity andsimplicity, flooding is an promising approach to provide reliabletransmissions.

    In this paper, a flooding-based routing protocol for IWSAN(REALFLOW) is upgraded based on previous research, aimingfor high reliability. To provide efficient and directionaltransmission, a controlled flooding-based mechanism is applied.Network management is further improved for better efficiencyand stability. REALFLOW is first compared with other fourflooding protocols via simulation. The results exhibit that REALFLOWoutperforms other advanced flooding protocols interms of reliability and consecutive transmission errors. Evencompared with pure flooding, REALFLOW achieves comparablereliability performance with decreased forwarding redundancy.To demonstrate the solution promising in reality, a workableIWSAN prototype is built, as well as the full implementation ofthe whole protocol stack including REALFLOW. A measurementconducted in a industrial manufacturing workshop reveals thathigh reliability and low application failure probability can beachieved, which brings more confidence of providing both reliablewireless sensing and actuating for industrial automation systems.

  • 3517.
    Yu, Tianyi
    et al.
    Halmstad University, School of Information Technology.
    Edén, Jenny
    Halmstad University, School of Information Technology.
    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.
    Larsson, Tony
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Traffic Situation Estimator for Adaptive Cruise Control2016In: 2016 IEEE 17th International Symposium on A World of Wireless, Mobile and Multimedia Networks (WoWMoM), Piscataway, NJ: IEEE, 2016, article id 7523567Conference paper (Refereed)
    Abstract [en]

    A traffic situation estimator capable of analyzing driving behavior utilizing an image analysis-based tracking module is presented. The behavior is analyzed by using a state machine driven counter to estimate the traffic rhythm and determine if the detected vehicles are approaching, getting away, have been overtaken or have overtaken the ego-vehicle. Depending on the result, the traffic situation estimator suggest different reactions, either to drive faster, slower or optionally suggest to overtake vehicles ahead to help the driver to follow the traffic rhythm which in turn will improve safety and energy efficiency. The proposed approach is implemented in a smart-phone and has shown good performance while testing the application on a two-lane highway. © 2016 IEEE.

  • 3518. Yu, Xianbin
    et al.
    Jia, Shi
    Pang, Xiaodan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab). RISE ACREO AB.
    Morioka, Toshio
    Oxenloewe, Leif K.
    Beyond 100 Gbit/s wireless connectivity enabled by THz photonics2017In: Transparent Optical Networks (ICTON), 2017 19th International Conference on, IEEE Computer Society, 2017, p. 1-4Conference paper (Refereed)
    Abstract [en]

    Beyond 100Gbit/s wireless connectivity is appreciated in many scenarios, such as big data wireless cloud, ultrafast wireless download, large volume data transfer, etc. In this paper, we will present our recent achievements on beyond 100Gbit/s ultrafast terahertz (THz) wireless links enabled by THz photonics.

  • 3519. Yu, Xianbin
    et al.
    Zhao, Ying
    Deng, Lei
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Tafur Monroy, Idelfonso
    Existing PON Infrastructure Supported Hybrid Fiber-Wireless Sensor Networks2012In: National Fiber Optic Engineers Conference, NFOEC 2012, 2012Conference paper (Refereed)
    Abstract [en]

    We propose a hybrid fiber wireless sensor network based on the existing PON infrastructure. The feasibility of remote sensing and PON convergence is experimentally proven by transmitting direct-sequence spread-spectrum wireless sensing and 2.5Gbps GPON signals.

  • 3520.
    Yu, Yang
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Electronic and embedded systems.
    Teijeira, Victor Diges
    KTH.
    Marranghello, Felipe
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Electronic and embedded systems.
    Dubrova, Elena
    KTH, School of Electrical Engineering and Computer Science (EECS), Electronics, Electronic and embedded systems.
    One-sided countermeasures for side-channel attacks can backfire2018In: WiSec 2018 - Proceedings of the 11th ACM Conference on Security and Privacy in Wireless and Mobile Networks, Association for Computing Machinery, Inc , 2018, p. 299-301Conference paper (Refereed)
    Abstract [en]

    Side-channel attacks are currently one of the most powerful attacks against implementations of cryptographic algorithms. They exploit the correlation between the physical measurements (power consumption, electromagnetic emissions, timing) taken at different points during the computation and the secret key. Some of the existing countermeasures offer a protection against one specific type of side channel only. We show that it can be a bad practice which can make exploitation of other side-channels easier. First, we perform a power analysis attack on an FPGA implementation of the Advanced Encryption Standard (AES) which is not protected against side-channel attacks and estimate the number of power traces required to extract its secret key. Then, we repeat the attack on AES implementations which are protected against fault injections by hardware redundancy and show that they can be broken with three times less power traces than the unprotected AES. We also demonstrate that the problem cannot be solved by complementing the duplicated module, as previously proposed. Our results show that there is a need for increasing knowledge about side-channel attacks and designing stronger countermeasures.

  • 3521.
    Yuan, Di
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Chen, Lei
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, The Institute of Technology.
    Karipidis, Eleftherios
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    On Optimal Link Activation with Interference Cancelation in Wireless Networking2013In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 62, no 2, p. 939-945Article in journal (Refereed)
    Abstract [en]

    A fundamental aspect in performance engineering of wireless networks is optimizing the set of links that can be concurrently activated to meet given signal-to-interference-and-noise ratio (SINR) thresholds. The solution of this combinatorial problem is the key element in scheduling and cross-layer resource management. In this paper, we assume multiuser decoding receivers, which can cancel strongly interfering signals. As a result, in contrast to classical spatial reuse, links being close to each other are more likely to be active concurrently. Our focus is to gauge the gain of successive interference cancellation (SIC), as well as the simpler, yet instructive, case of parallel interference cancellation (PIC), in the context of optimal link activation. We show that both problems are NP-hard and develop compact integer linear programming formulations that enable to approach global optimality. We provide an extensive numerical performance evaluation, indicating that for low to medium SINR thresholds the improvement is quite substantial, especially with SIC, whereas for high SINR thresholds the improvement diminishes and both schemes perform equally well.

  • 3522.
    Yuan, Xiaolong
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Wu, X.
    Signell, S.
    Continuous-time quadrature bandpass sigma delta modulators with different feedback DAC2008In: IEEE Int. Conf. Circuits Syst. Commun., ICCSC, 2008, p. 580-583Conference paper (Refereed)
    Abstract [en]

    Continuous time (CT) quadrature bandpass sigma delta modulators (QBSDM) are widely used in wireless receivers recently due to its inherent anti-aliasing filtering and complex filtering embedded in the loops to efficiently realize asymmetric noise-shaping. The complex noise-transfer-function (NTF) can be realized with complex coefficients or by implementing the loop as a cascade of complex integrators with only real coefficients, which is desirable due to its lower sensitivity to loop mismatch. In this paper, we will study the effect of different feedback waveforms inside the modulator on the NTF of quadrature sigma delta modulators. Complex NTF design is discussed for different bandpass center frequencies relative to the sampling frequency.

  • 3523.
    Yuan, Zhao
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Hesamzadeh, Mohammad Reza
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Implementing zonal pricing in distribution network: The concept of pricing equivalence2016In: IEEE Power and Energy Society General Meeting, IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    Distribution locational marginal pricing (DLMP) is critical market mechanism to boost services from distributed energy resources (DER). This paper propose to design zonal pricing in distribution network according to the concept of pricing equivalence (PE). The rules of the zonal pricing are derived. We prove that equivalent load shift from demand response can be achieved by zonal pricing if pricing equivalence is deployed. Convex AC optimal power flow (OPF) is used to calculate zonal prices. The benefits of convex AC OPF are more accurate energy pricing and global optimization target. The responsive load with passive load controllers are modeled and solved in GAMS platform. Different zonal pricing approaches (PE, reference node and average of nodal prices) are compared. IEEE 14-bus network and two IEEE 13-node networks are connected to be an illustrative test case offering numerical results. The results show that zonal pricing designed according to PE can achieve the same load shift effects and quite close consumer payments as nodal pricing. PE outperform other zonal pricing approaches prominently in congested network situations.

  • 3524.
    Yue, Jing
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Pang, Zhibo
    ABB Corp Res, Wireless Commun, S-72178 Vasteras, Sweden..
    Distributed Fog Computing Based on Batched Sparse Codes for Industrial Control2018In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 14, no 10, p. 4683-4691Article in journal (Refereed)
    Abstract [en]

    In an industrial automation system, one of the most important parts is control loop. Fog computing is a potential solution for industrial control in time-critical applications as it provides distributed computing services closer to the connected devices. However, a huge amount of data exchanging among fog nodes causes high communication load, which constrains the overall response time from fog nodes to actuators. In this paper, we consider the erasure environment, batched sparse (BATS) codes are applied to the Map and the Data Shuffling stages of distributed fog computing process to reduce both the communication and the computation loads. The communication loads of the uncoded, the coded, and the proposed BATS-based schemes over erasure channels are calculated, respectively. Numerical results show that the BATS-based scheme can reduce the communication and the computation loads simultaneously, and furthermore reduce the overall response time from fog nodes to the actuators.

  • 3525. Yun, S. -Y
    et al.
    Proutiere, Alexandre
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Distributed proportional fair load balancing in heterogenous systems2015In: Performance Evaluation Review, ACM Press, 2015, Vol. 43, no 1, p. 17-30Conference paper (Refereed)
    Abstract [en]

    We consider the problem of distributed load balancing in heterogenous parallel server systems, where the service rate achieved by a user at a server depends on both the user and the server. Such heterogeneity typically arises in wireless networks (e.g., servers may represent frequency bands, and the service rate of a user varies across bands). We assume that each server equally shares in time its capacity among users allocated to it. Users initially attach to an arbitrary server, but at random instants of time, they probe the load at a new server and migrate there if this improves their service rate. The dynamics under this distributed load balancing scheme, referred to as Random Local Search (RLS), may be interpreted as those generated by strategic players updating their strategy in a load balancing game. In closed systems, where the user population is fixed, we show that this game has pure Nash Equilibriums (NEs), and that these equilibriums get close to a Proportionally Fair (PF) allocation of users to servers when the user population grows large. We provide an anytime upper bound of the gap between the allocation under RLS and the PF allocation. In open systems, where users randomly enter the system and leave upon service completion, we establish that the RLS algorithm stabilizes the system whenever this it at all possible under centralized load balancing schemes, i.e., it is throughput-optimal. The proof of this result relies on a novel Lyapounov analysis that captures the dynamics due to both users’ migration and their arrivals and departures. To our knowledge, the RLS algorithm constitutes the first fully distributed and throughputoptimal load balancing scheme in heterogenous parallel server systems. We extend our analysis to various scenarios, e.g. to cases where users can be simultaneously served by several servers. Finally we illustrate through numerical experiments the efficiency of the RLS algorithm.

  • 3526.
    Yunda Lozano, Daniel
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Improving vertical handover performance for RTP streams containing voice: Using network parameters to predict future network conditions in order to make a vertical handover decision2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Wireless local area networks WLAN and Voice over IP technologies enable local low cost wireless telephony, while cellular networks offer wide-area coverage. The use of dual mode WLAN-cellular terminals should allow cost savings by automatically switching from GSM to WLAN networks whenever it is feasible. However, in order to allow user mobility during a call, a handover procedure for transferring a call between the WLAN interface and the cellular network should be defined. The decision algorithm that triggers such a handover is critical to maintain voice quality and uninterrupted communication. Information or measurements collected from the network may be used to anticipate when the connection will degrade to such a point that a handover is desirable in order to allow a sufficient time span for the handover’s successful execution. It is the delay in detecting when to make a handover and the time to execute it that motivates the need for a prediction.

    The goal of this thesis is therefore to present a method to predict when a handover should be made based upon network conditions. We selected a number of WLAN and VoIP software tools and adapted them to perform the measurements. These tools allowed us to measure parameters of the WLAN’s physical and link layers. Packet losses and jitter measurements were used as well. We have assumed that there is ubiquitous cellular coverage so that we only have to be concerned with upward handovers (i.e, from the WLAN to the cellular network and not the reverse). Finally we have designed and evaluated a mechanism that triggers the handover based in these measurements.

  • 3527.
    Zachariah, Dave
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Dwivedi, Satyam
    KTH Royal Inst Technol, Dept Elect Engn, SE-10044 Stockholm, Sweden..
    Handel, Peter
    KTH Royal Inst Technol, Dept Elect Engn, SE-10044 Stockholm, Sweden..
    Stoica, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Scalable and Passive Wireless Network Clock Synchronization in LOS Environments2017In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, no 6, p. 3536-3546Article in journal (Refereed)
    Abstract [en]

    Clock synchronization is ubiquitous in wireless systems for communication, sensing, and control. In this paper, we design a scalable system in which an indefinite number of passively receiving wireless units can synchronize to a single master clock at the level of discrete clock ticks. Accurate synchronization requires an estimate of the node positions to compensate the time-of-flight transmission delay in line-of-sight environments. If such information is available, the framework developed here takes position uncertainties into account. In the absence of such information, as in indoor scenarios, we propose an auxiliary localization mechanism. Furthermore, we derive the Cramer-Rao bounds for the system, which show that it enables synchronization accuracy at sub-nanosecond levels. Finally, we develop and evaluate an online estimation method, which is statistically efficient.

  • 3528. Zafar, B.
    et al.
    Ben Slimane, Slimane
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Communication Systems, CoS (closed 2012-01-01).
    Javed, Muhammad Umar
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Communication Systems, CoS (closed 2012-01-01).
    Network product coding2010In: 2010 7th IEEE Consumer Communications and Networking Conference, CCNC 2010, IEEE , 2010, p. -266Conference paper (Refereed)
    Abstract [en]

    Network coding is a useful tool to increase the multicast capacity of networks. The traditional approach to network coding involving XOR operation has several limitations such as low robustness and can support only two users/packets at a time,per relay, in the mixing process to achieve optimal error performance. We propose the employment of product coding at the relay station instead of xor and investigate such a system where we use the relay to generate product codes by combining packets from different users. Our scheme uses relays to transmit only the redundancy of the product code instead of the whole product code. We seek to employ product coding can be able to support more than two users/packets per relay per slot, while maintaining a good error performance. Our scheme can accomodate as many users per relay as the costituent block code allows, thus reducing the number of relays required in the network.Product codes also offer increased robustness and flexibility as well as several other advantages, such as proper structure for burst error correction without extra interleaving. We compare the performance of such a scheme to the conventional xor scheme and see that our scheme not only reduces the number of relays required but gives improved error performance as well as. Another encouraging result is that our scheme starts to significantly outperform the conventional one by introducing a gain at the relay.

  • 3529.
    Zafar, Bilal
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Network Coding Employing Product Coding at Relay Stations2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Network coding is a useful tool to increase the multicast capacity of networks. The traditional approach to network coding involving XOR operation has several limitations such as low robustness and can support only two users/packets at a time,per relay, in the mixing process to achieve optimal error performance. We propose the employment of product coding at the relay station instead of xor and investigate such a system where we use the relay to generate product codes by combining packets from different users.Our scheme uses relays to transmit only the redundancy of the product code instead of the whole product code.We seek to employ product coding can be able to support more than two users/packets per relay per slot,while maintaining a good error performance. Our scheme can accomodate as many users per relay as the costituent block code allows, thus reducing the number of relays required in the network. Product codes also offer increased robustness and flexibility as well as several other advantages, such as proper structure for burst error correction without extra interleaving. We compare the performance of such a scheme to the conventional xor scheme and see that our scheme not only reduces the number of relays required but gives improved error performance as well as. Another encouraging result is that our scheme starts to significantly outperform the conventional one by introducing a gain at the relay.

  • 3530.
    Zahidi, Salman
    Linköping University, Department of Electrical Engineering, Information Coding.
    Biometrics - Evaluation of Current Situation2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Information security has always been a topic of concern in the world as an emphasis on new techniques to secure the identity of a legitimate user is regarded as top priority. To counter such an issue, we have a traditional way of authentication factors “what you have” and “what you know” in the form of smart cards or passwords respectively. But biometrics is based on the factor “who are you” by analyzing human physical or behavioral characteristics. Biometrics has always been an efficient way of authorization and is now considered as a $1500 million industry where fingerprints dominate the biometrics while iris is quickly emerging as the most desirable form of biometric technique.The main goal of this thesis is to compare and evaluate different biometrics techniques in terms of their purpose, recognition mechanism, market value and their application areas. Since there are no defined evaluating criteria, my method of evaluation was based on a literature survey from internet, books, IEEE papers and technical surveys. Chapter 3 is focused on different biometrics techniques where I discuss them briefly but in chapter 4, I go deeper into Iris, fingerprints, facial techniques which are prominent in biometrics world. Lastly, I had a general assessment of the biometrics, their future growth and suggested specific techniques for different environment like access controls, e-commerce, national ids, and surveillance.

  • 3531. Zaidi, A. A.
    et al.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Stabilization of noisy plants over a Gaussian interference channel2014In: IWCIT 2014 - Iran Workshop on Communication and Information Theory, 2014Conference paper (Refereed)
    Abstract [en]

    Remote stabilization of two noisy linear plants over a symmetric Gaussian interference channel with possibly noisy feedback from controllers to the plants is studied. Each plant is monitored by a separate sensor which communicates its observations to a separate controller over a Gaussian interference channel. The controllers aim at stabilizing the two plants in mean-square sense. The plant noise is assumed to be additive white Gaussian distributed. A delay-free sensing and control scheme is proposed, which is an adaptation of the Schalkwijk-Kailath type coding schemes developed for transmission of reliable information over channels with noiseless feedback. The conditions that guarantee the stabilization of the noisy plants under the proposed scheme are derived, extending the results that are known for mean-square stabilization of noiseless plants over noiseless feedback channels. Numerical results indicate that the stabilizability is not affected by the inclusion of an additive Gaussian noise in the plant models under the proposed scheme.

  • 3532.
    Zaki, Ahmed
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Venkitaraman, Arun
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Chatterjee, Saikat
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Rasmussen, Lars Kildehöj
    Distributed Greedy Sparse Learning over Doubly Stochastic Networks2017In: 2017 25TH EUROPEAN SIGNAL PROCESSING CONFERENCE (EUSIPCO), IEEE , 2017, p. 361-364Conference paper (Refereed)
    Abstract [en]

    In this paper, we develop a greedy algorithm for sparse learning over a doubly stochastic network. In the proposed algorithm, nodes of the network perform sparse learning by exchanging their individual intermediate variables. The algorithm is iterative in nature. We provide a restricted isometry property (RIP)-based theoretical guarantee both on the performance of the algorithm and the number of iterations required for convergence. Using simulations, we show that the proposed algorithm provides good performance.

  • 3533.
    Zaki, Ahmed
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Wang, Chao
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Rasmussen, Lars K.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Combining interference alignment and Alamouti codes for the 3-user MIMO interference channel2013In: 2013 IEEE Wireless Communications and Networking Conference (WCNC), New York: IEEE , 2013, p. 3563-3567Conference paper (Refereed)
    Abstract [en]

    The interference channel (IC) is the basic underlying channel model for many practical multi-terminal communication scenarios. Here, we consider a modified three-user IC with dual-antenna transmitters and receivers where we allow one receiver to have a finite-rate unidirectional link to another receiver. This kind of receiver-to-receiver link may exist in cellular networks with base-station backhaul. For this scenario we propose a scheme that combines the interference-cancellation capability of Alamouti codes with the subspace-overlapping property of interference alignment to achieve a sum-rate of three symbols/channel use. The scheme does also simultaneously provide a diversity gain of two for every symbol which significantly improves the bit-error rate performance compared to zero-forcing techniques.

  • 3534.
    Zamaere, Bruce
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Hidell, Markus
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Sjödin, Peter
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    CVPN: A multi-homed VPN solution for remote patient monitoring2012In: 2012 IEEE 14th International Conference on e-Health Networking, Applications and Services, Healthcom 2012, IEEE , 2012, p. 279-285Conference paper (Refereed)
    Abstract [en]

    This paper addresses the challenges of reliably, and securely, extending a healthcare provider's network into the homes of its patients in order to provide Remote Patient Monitoring (RPM) services. It describes the Carenet Virtual Private Network (CVPN) solution, a multi-homed VPN solution implemented as a virtual device driver under Linux. We describe CVPN's architecture and implementation, motivating its design decisions. The initial experimental evaluation, of our proof-of-concept prototype, shows that CVPN's per packet overhead, forwarding delay, and fail-over time are reasonable for healthcare monitoring applications and time-sensitive synchronous communications.

  • 3535.
    Zander, Jens
    KTH.
    Beyond the Ultra-Dense Barrier: Paradigm Shifts on the Road beyond 1000x Wireless Capacity2017In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 24, no 3, p. 96-102Article in journal (Refereed)
    Abstract [en]

    It has become increasingly clear that the current design paradigm for mobile broadband systems is not a scalable and economically feasible way to solve the expected future "capacity crunch," in particular in indoor locations with large user densities. "Moore's law," for example, state-of-the art signal processing and advanced antenna techniques now being researched, as well as more millimeter wave spectrum, indeed provide more capacity, but are not the answer to the three to four orders of magnitude more capacity at today's cost, that is needed. We argue that solving the engineering problem of providing high data rates alone is not sufficient. Instead, we need to solve the techno-economic problem to find both business models and scalable technical solutions that provide extreme area capacity for a given cost and energy consumption. In this article we will show that achieving very high capacities is indeed feasible in indoor environments. However, to become economically viable, approaches with radically different fundamental cost factors compared to those used in today's cellular systems are needed. To reach very high capacity we must venture beyond the ultra-dense barrier, that is, networks where the number of access points in an area is (considerably) larger than the active number of mobile terminals. In such networks area capacities of more than 1 Gb/s/m2 are perfectly feasible. The problem set encountered in such UDN is very different from conventional cellular systems and their solution requires conceptually new tools. We will address some of the fundamental aspects and performance limits, modeling of propagation, deployment and user traffic, and discuss the techno-economics of various network architectures. Finally we will summarize some of the most significant unsolved research questions in the field.

  • 3536.
    Zander, Jens
    et al.
    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.
    Mähönen, Petri
    Riding the Data Tsunami in the Cloud: Myths and Challenges in Future Wireless Access2013In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 51, no 3, p. 145-151Article in journal (Refereed)
    Abstract [en]

    Data rates of mobile communications have increased dramatically during the last decade. The industry predicts an exponential increase of data traffic that would correspond to a 1000-fold increase in traffic between 2010 and 2020. These figures are very similar to ones reported during the last Internet boom. In this article we assess the realism of these assumptions. We conjecture that wireless and mobile Internet access will emerge as a dominant technology. A necessary prerequisite for this development is that wireless access is abundant and becomes (almost) free. A consequence is that the projected capacity increase must be provided at the same cost and energy consumption as today. We explore technical and architectural solutions that have realistic possibility to achieve these targets. We ask if Moore's law, which has successfully predicted the tremendous advances in computing and signal processing, will also save the day for high-speed wireless access. We argue that further improvements of the PHY layer are possible, but it is unlikely that this alone provides a viable path. The exponential traffic increase has to be matched mainly by increasing the density of the access networks as well as providing a modest amount of extra spectrum. Thus, the future research challenges are in designing energy-and cost-efficient short-range architectures and systems that support super-dense deployments. A non-technical complication is that such infrastructures are likely to lead to highly fragmented markets with a large number of operators and infrastructure owners.

  • 3537.
    Zander, Jens
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Rasmussen, Lars K.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Maehoenen, Petri
    Petrova, Marina
    Jantti, Riku
    Kronander, Jonas
    On the scalability of cognitive radio:: Assessing the commercial viability of secondary spectrum access2013In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 20, no 2, p. 28-35Article in journal (Refereed)
    Abstract [en]

    We report results from the recently finished QUASAR project, which has studied overall system aspects of cognitive radio technologies and has paid attention particularly to the economic viability of different use cases. We find that successful secondary sharing goes far beyond the detection of spectrum holes. Large-scale commercial success requires that secondary systems are scalable so that a large number of users can be served in an economically viable fashion. Our key finding is that secondary spectrum use is not an attractive method for most of the commercially interesting scenarios, from neither a business nor technical perspective. Perhaps somewhat surprisingly, the likely commercial "sweet spot" for secondary sharing in the lower frequency bands is short-range indoor communications. We also find that regulation does not currently present a significant barrier in Europe or the United States.

  • 3538.
    Zandieh, Behdis
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Indoor Wireless Local Area Network (WLAN): Measurement and Modeling from a user perspective2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    If we had detailed wireless local area network (WLAN) coverage maps, both staff and equipment could be used more efficiently, for example, less time would be spent searching for connectivity. In addition, system administrators could understand their WLAN's utilization better, thus enabling better planning for where to install new access points, where to remove access points, where to change the type of antenna, etc. This thesis concerns creating detailed indoor coverage models by using measured network performance - in order to enable both users and administrators to visualize the network coverage. Today a user can only easily know about the access points that they currently hear – in the location where they currently are. Giving the users and administrators access to a model of the entire campus coverage will allow them to understand not only the _local_ coverage, but the patterns of coverage (or lack there of). However, no efficient modeling techniques are currently available for those deploying and operating indoor WLANs.

    The thesis begins with some general background information and then examines a number of WLAN survey tools; in terms of both their performance and cost. Following this a number of related projects are presented. This background provides the motivation for why a new tool is needed and what functions such a tool should have.

    Next a site survey of the KTH campus in Kista was conducted using a newly developed survey application. This application was developed to better meet the requirements derived from the missing functionality of existing tools. In addition, developing this application gave the author an opportunity to learn a new objectoriented programming language, i.e. C# and the .NET environment. Learning to use this new environment was essential to building both an easy to use application and collecting the data from the system - the later was often not straight-forward.

    ne of the key issues after data collection is how to present the collected data to the user and how this varies depending upon the user’s interests and task. An initial representation of the experimental data is presented as a manually painted coverage map overlayed onto a map. Next the thesis examines how to integrate the experimental data using Google’s SketchUp in order to build a 3D model of the WLAN coverage on this campus.

    Future work related to this thesis should focus on how to automate the collection of data and how to automate the presentation of the resulting experimental data.

  • 3539.
    Zapolskas, Vytautas
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Securing Cloud Storage Service2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cloud computing brought flexibility, scalability, and capital cost savings to the IT industry. As more companies turn to cloud solutions, securing cloud based services becomes increasingly important, because for many organizations, the final barrier to adopting cloud computing is whether it is sufficiently secure.

    More users rely on cloud storage as it is mainly because cloud storage is available to be used by multiple devices (e.g. smart phones, tablets, notebooks, etc.) at the same time. These services often offer adequate protection to user's private data. However, there were cases where user's private data was accessible to other users, since this data is stored in a multi-tenant environment. These incidents reduce the trust of cloud storage service providers, hence there is a need to securely migrate data from one cloud storage provider to another.

    This thesis proposes a design of a service for providing Security as a Service for cloud brokers in a federated cloud. This scheme allows customers to securely migrate from one provider to another. To enable the design of this scheme, possible security and privacy risks of a cloud storage service were analysed and identified. Moreover, in order to successfully protect private data, data protection requirements (for data retention, sanitization, and processing) were analysed. The proposed service scheme utilizes various encryption techniques and also includes identity and key management mechanisms, such as "federated identity management".

    While our proposed design meets most of the defined security and privacy requirements, it is still unknown how to properly handle data sanitization, to meet data protection requirements, and provide users data recovery capabilities (backups, versioning, etc.).

  • 3540.
    Zappone, Alessio
    et al.
    TU Dresden, Dresden, Germany.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Sanguinetti, Luca
    University of Pisa, Italy; CentraleSupelec, France.
    Jorswieck, Eduard
    TU Dresden, Dresden, Germany.
    A Framework for Globally Optimal Energy-Efficient Resource Allocation in Wireless Networks2016Conference paper (Refereed)
  • 3541.
    Zdravkovic, Jelena
    et al.
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV.
    Zikra, Iyad
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV.
    Ilayperuma, Tharaka
    An MDA method for service modeling by formalizing REA and open-edi business frameworks with SBVR2011In: 4th IFIP WG 8.1 Working Conference on Method Engineering, ME 2011, 2011, p. 219-224Conference paper (Refereed)
    Abstract [en]

    Business frameworks offer great opportunities of communication between people for working on the enterprise system engineering processes, as well as for eliciting services that the enterprise can offer in collaboration contexts. However, these kinds of frameworks, such as Resource-Event-Agent and Open-edi, recently unified in Open-edi Business Ontology (OeBTO), lack formal representations. This fact considerably limits their use in system development, particularly in model-driven development methods where the efficiency of transformations is of great importance. In this paper we suggest a formalization of OeBTO using OMG's standard Semantics of Business Vocabulary and Business Rules (SBVR), as a method for creating a service-centric business model. This makes it possible to provide the necessary formal logic foundation to allow automatic processing of the business model and its transformation to a system-level service model. An example from the bank loan business sector is used to argument the application of the method.

  • 3542.
    Zeadally, Sherali
    et al.
    Univ Dist Columbia, Dept Comp Sci & Informat Technol, Network Syst Lab, Washington, DC 20008 USA..
    Hunt, Ray
    Univ Canterbury, Coll Engn, Dept Comp Sci & Software Engn, Christchurch 1, New Zealand..
    Chen, Yuh-Shyan
    Natl Taipei Univ, Dept Comp Sci & Informat Engn, San Shia, Taipei County, Taiwan..
    Irwin, Angela
    Univ S Australia, Sch Comp & Informat Sci, Mawson Lakes, SA 5095, Australia..
    Hassan, Aamir
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Vehicular ad hoc networks (VANETS): status, results, and challenges2012In: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 50, no 4, p. 217-241Article in journal (Refereed)
    Abstract [en]

    Recent advances in hardware, software, and communication technologies are enabling the design and implementation of a whole range of different types of networks that are being deployed in various environments. One such network that has received a lot of interest in the last couple of years is the Vehicular Ad-Hoc Network (VANET). VANET has become an active area of research, standardization, and development because it has tremendous potential to improve vehicle and road safety, traffic efficiency, and convenience as well as comfort to both drivers and passengers. Recent research efforts have placed a strong emphasis on novel VANET design architectures and implementations. A lot of VANET research work have focused on specific areas including routing, broadcasting, Quality of Service (QoS), and security. We survey some of the recent research results in these areas. We present a review of wireless access standards for VANETs, and describe some of the recent VANET trials and deployments in the US, Japan, and the European Union. In addition, we also briefly present some of the simulators currently available to VANET researchers for VANET simulations and we assess their benefits and limitations. Finally, we outline some of the VANET research challenges that still need to be addressed to enable the ubiquitous deployment and widespead adoption of scalable, reliable, robust, and secure VANET architectures, protocols, technologies, and services.

  • 3543.
    Zeeck, Simon
    KTH, Superseded Departments, Teleinformatics.
    Cellular Interworking: Handover between WATM and GSM1998Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In a wireless environment, it is interesting to roam between different wireless systems, especially if the coverage of one or more of these systems are limited to a certain restricted area, or if there is a cost difference. My work has focused on the support of continuous handover in such a case. The work has focused on Wireless ATM and GSM as bearers for data traffic. The mobile terminal is considered to connect to the GSM or Wireless ATM network. Internet (IP networking) is considered to be the aim of the connection.

    UMTS will probably be the base for new cellular systems. The UMTS core network will most likely be based on ATM. This is what is suggested in the standardization and has support from both Ericsson and Nokia. The WATM is an interesting option for "high speed" wireless network interface that can be connected to UMTS.

    The solution has tried the approch of combining layer 2 tunneling with layer 3 signalling and investigated another solution than network layer mobility.The reasons to investigate this has been:

    • Layer 2 tunneling is a well-know and proven concept in cellular networks
    • The layer 2 connection can be transparently changed while being mobile.
    • Both QoS and traffic parameters in layer2 (e.g., ATM) can be used
    • The freedom and power of IP on layer 3 for signaling (and for data, of course)
  • 3544.
    Zennaro, Marco
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Telecommunication Systems Laboratory, TSLab.
    Bagula, Antoine
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Telecommunication Systems Laboratory, TSLab.
    Ntareme, Hervé
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Telecommunication Systems Laboratory, TSLab.
    Inggs, Gordon
    Scott, Simon
    On the relevance of open wireless sensors for NGN2009In: International Telecommunication Union - Proceedings of the 2009 ITU-T Kaleidoscope Academic Conference: Innovations for Digital Inclusion, K-IDI 2009, IEEE conference proceedings, 2009, p. 193-200Conference paper (Refereed)
    Abstract [en]

    Open Wireless Sensors are based on the Open Source Software and Open Source Hardware paradigms. The code used to program them and the information about the hardware design are freely released. We present the main characteristics of Open Wireless Sensor Networks (OWSNs) and report on two examples with the experimental results revealing the performance of OWSNs in terms of link quality and battery life. We demonstrate the relevance of using OWSNs in Next Generation Networks by showing the advantages of the Open Source model when applied to Wireless Sensor networks in terms of cost, personalisation and independence from a single entity as compared to proprietary solutions.

  • 3545.
    Zenteno, Efrain
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Digital Compensation Techniques for Transmitters in Wireless Communications Networks2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Since they appeared, wireless technologies have deeply transformed our society. Today, wireless internet access and other wireless applications demandincreasingly more traffic. However, the continuous traffic increase can be unbearableand requires rethinking and redesigning the wireless technologies inmany different aspects. Aiming to respond to the increasing needs of wirelesstraffic, we are witnessing a rapidly evolving wireless technology scenario.This thesis addresses various aspects of the transmitters used in wireless communications.Transmitters present several hardware (HW) impairments thatcreate distortions, polluting the radio spectrum and decreasing the achievabletraffic in the network. Digital platforms are now flexible, robust and cheapenough to enable compensation of HW impairments at the digital base-bandsignal. This has been coined as ’dirty radio’. Dirty radio is expected in future transmitters where HW impairments may arise to reduce transmitter cost or to enhance power efficiency. This thesis covers the software (SW) compensation schemes of dirty radio developed for wireless transmitters. As describedin the thesis, these schemes can be further enhanced with knowledge of thespecific signal transmission or scenarios, e.g., developing cognitive digital compensationschemes. This can be valuable in today’s rapidly evolving scenarioswhere multiple signals may co-exist, sharing the resources at the same radiofrequency (RF) front-end. In the first part, this thesis focuses on the instrumentation challenges andHWimpairments encountered at the transmitter. A synthetic instrument (SI)that performs network analysis is designed to suit the instrumentation needs.Furthermore, how to perform nonlinear network analysis using the developedinstrument is discussed. Two transmitter HW impairments are studied: themeasurement noise and the load impedance mismatch at the transmitter, asis their coupling with the state-of-the-art digital compensation techniques.These two studied impairments are inherent to measurement systems and areexpected in future wireless transmitters. In the second part, the thesis surveys the area of behavioral modeling and digital compensation techniques for wireless transmitters. Emphasis is placed on low computational complexity techniques. The low complexity is motivated by a predicted increase in the number of transmitters deployed in the network, from base stations (BS), access points and hand-held devices. A modeling methodology is developed that allows modeling transmitters to achieve both reduced computational complexity and low modeling error. Finally, the thesis discusses the emerging architectures of multi-channel transmittersand describes their digital compensation techniques. It revises the MIMOVolterra series formulation to address the general modeling problem anddrafts possible solutions to tackle its dimensionality. In the framework of multi-channel transmitters, a technique to compensate nonlinear multi-carrier satellite transponders is presented. This technique is cognitive because it uses the frequency link planning and the pulse-shaping filters of the individual carriers. This technique shows enhanced compensation ability at reduced computational complexity compared to the state-of-the-art techniques and enables the efficient operation of satellite transponders.

  • 3546.
    Zenteno, Efrain
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Digital Compensation Techniques for Transmitters inWireless Communications Networks2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Since they appeared, wireless technologies have deeply transformed our society. Today, wireless internet access and other wireless applications demandincreasingly more traffic. However, the continuous traffic increase can be unbearableand requires rethinking and redesigning the wireless technologies inmany different aspects. Aiming to respond to the increasing needs of wirelesstraffic, we are witnessing a rapidly evolving wireless technology scenario.This thesis addresses various aspects of the transmitters used in wireless communications.Transmitters present several hardware (HW) impairments thatcreate distortions, polluting the radio spectrum and decreasing the achievabletraffic in the network. Digital platforms are now flexible, robust and cheapenough to enable compensation of HW impairments at the digital base-bandsignal. This has been coined as ’dirty radio’. Dirty radio is expected in future transmitters where HW impairments may arise to reduce transmitter cost or to enhance power efficiency. This thesis covers the software (SW) compensation schemes of dirty radio developed for wireless transmitters. As describedin the thesis, these schemes can be further enhanced with knowledge of thespecific signal transmission or scenarios, e.g., developing cognitive digital compensationschemes. This can be valuable in today’s rapidly evolving scenarioswhere multiple signals may co-exist, sharing the resources at the same radiofrequency (RF) front-end. In the first part, this thesis focuses on the instrumentation challenges andHWimpairments encountered at the transmitter. A synthetic instrument (SI)that performs network analysis is designed to suit the instrumentation needs.Furthermore, how to perform nonlinear network analysis using the developedinstrument is discussed. Two transmitter HW impairments are studied: themeasurement noise and the load impedance mismatch at the transmitter, asis their coupling with the state-of-the-art digital compensation techniques.These two studied impairments are inherent to measurement systems and areexpected in future wireless transmitters. In the second part, the thesis surveys the area of behavioral modeling and digital compensation techniques for wireless transmitters. Emphasis is placed on low computational complexity techniques. The low complexity is motivated by a predicted increase in the number of transmitters deployed in the network, from base stations (BS), access points and hand-held devices. A modeling methodology is developed that allows modeling transmitters to achieve both reduced computational complexity and low modeling error. Finally, the thesis discusses the emerging architectures of multi-channel transmittersand describes their digital compensation techniques. It revises the MIMOVolterra series formulation to address the general modeling problem anddrafts possible solutions to tackle its dimensionality. In the framework of multi-channel transmitters, a technique to compensate nonlinear multi-carrier satellite transponders is presented. This technique is cognitive because it uses the frequency link planning and the pulse-shaping filters of the individual carriers. This technique shows enhanced compensation ability at reduced computational complexity compared to the state-of-the-art techniques and enables the efficient operation of satellite transponders.

  • 3547.
    Zenteno, Efrain
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Amin, Shoaib
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Isaksson, Magnus
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Combating the Dimensionality of Nonlinear MIMOAmplifier Predistortion by Basis Pursuit2014In: Proceedings of the 44th European Microwave Conference, 2014, p. 833-836Conference paper (Refereed)
    Abstract [en]

    A general description of nonlinear dynamic MIMOsystems, given by Volterra series, has significantly larger complex-ity than SISO systems. Modeling and predistortion of MIMOamplifiers consequently become unfeasible due to the largenumber of basis functions. We have designed digital predistortersfor a MIMO amplifier using a basis pursuit method for reducingmodel complexity. This method reduces the numerical problemsthat appear in MIMO Volterra predistorters due to the largenumber of basis functions. The number of basis functions wasreduced from 1402 to 220 in a 2x2 MIMO amplifier and from127 to 13 in the corresponding SISO case. Reducing the numberof basis functions caused an increase of approximately 1 dB ofmodel error and adjacent channel power ratio.

  • 3548.
    Zenteno, Efrain
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. ACCESS Linnaeus Centre, Department of Signal Processing, KTH Royal Institute of Technology, Stockholm.
    Amin, Shoaib
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. ACCESS Linnaeus Centre, Department of Signal Processing, KTH Royal Institute of Technology, Stockholm.
    Isaksson, Magnus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Händel, Peter
    ACCESS Linnaeus Centre, Department of Signal Processing, KTH Royal Institute of Technology, Stockholm.
    Combating the Dimensionality of Nonlinear MIMO Amplifier Predistortion by Basis Pursuit2014In: Proceedings of the 44th European Microwave Conference, 2014, p. 833-836Conference paper (Refereed)
    Abstract [en]

    A general description of nonlinear dynamic MIMO systems, given by Volterra series, has significantly larger complexity than SISO systems. Modeling and predistortion of MIMO amplifiers consequently become unfeasible due to the large number of basis functions. We have designed digital predistorters for a MIMO amplifier using a basis pursuit method for reducing model complexity. This method reduces the numerical problems that appear in MIMO Volterra predistorters due to the large number of basis functions. The number of basis functions was reduced from 1402 to 220 in a 2x2 MIMO amplifier and from 127 to 13 in the corresponding SISO case. Reducing the number of basis functions caused an increase of approximately 1 dB of model error and adjacent channel power ratio.

  • 3549.
    Zepernick, Hans-Jürgen
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Iqbal, Muhammad Imran
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Khatibi, Siamak
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Quality of Experience of Digital Multimedia Broadcasting Services: An Experimental Study2016In: 2016 IEEE Sixth International Conference on Communications and Electronics (ICCE), IEEE, 2016, p. 437-442Conference paper (Refereed)
    Abstract [en]

    Digital multimedia broadcasting (DMB), also know as mobile TV, has been developed as a digital radio transmission technology that supports multimedia services such as TV, radio and datacasting. Especially, the terrestrial version of DMB, referred to as T-DMB, has been widely deployed in South Korea to deliver multimedia services to mobile devices ranging from smartphones to laptops, car navigation systems, and telematic devices for automotives. Although T-DMB is claimed to theoretically work without difficulties in vehicles with speeds up to 300 km/h, in practice, occasional skips and other temporal and spatial artifacts have been observed. In this paper, we provide an experimental study of the Quality of Experience (QoE) of T-DMB with focus on TV services. The study is based on a measurement campaign that was conducted in a live T-DMB system in South Korea consisting of TV broadcasters and DMB receivers in vehicles. In particular, a comprehensive subjective test has been conducted on the DMB test material that was obtained in the measurement campaign. A statistical analysis of the user ratings obtained from the subjective tests is reported to quantify the QoE of T-DMB in terms of mean opinion scores (MOSs) and higher order statistics. The obtained results may be used to develop related QoE models for this type of systems and services. In particular, the results may suggest to exploit insights obtained from higher order statistics such as skewness and kurtosis into QoE modeling rather than considering only MOS and variance.

  • 3550.
    Zerouali, Mehdi
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    VoIP Communications over WLANs: Implementation of a new downlink transmission protocol2010Report (Other academic)
    Abstract [en]

    Voice over IP (VoIP) is becoming more and more popular every day. The number of VoIP service providers is continuously increasing along with the number of customers they serve. Moreover, the latest generation of smartphones and mobile devices now incorporate VoIP support. This enables users within a wireless local area network (WLAN) cell to exchange VoIP traffic with other peers.

    This new traffic potentially poses a problem for WLANs, as the WLAN access point could be required to handle a large number of small packets of encoded speech. Since the access to the media can only be made by one node at a time, all of the devices must contend to access it. If there are multiple calls between nodes in the WLAN and nodes in the fixed network, then all of these packets must go to and from the access point. Moreover the access point needs to transmit the downlink traffic for all of these nodes. Because the Access Point has the same probability of getting access to the media as any other node, this can lead to high delays, and limits the maximum number of simultaneous calls to a rather small number, despite the increasing data rates that the WLAN interfaces are capable of.</p>This project implements and evaluates a new solution that consists of aggregating downlink packets at the access point and transmitting a large multicast packet containing a set of voice frames that need to be sent to nodes within the cell. A demultiplexing process at node extracts the appropriate RTP content from the multicast packet and delivers it locally.

68697071727374 3501 - 3550 of 3669
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