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  • 2951.
    Xiaoyu, Wei
    et al.
    Ericsson Research, Isafjordsgatan 14E, 164 93 Kista, Sweden.
    Larsson, Peter
    Ericsson Research, Isafjordsgatan 14E, 164 93 Kista, Sweden.
    A Joint Power and Rate Control Algorithm and Fairness Enhancement for Multiuser OFDM System2008In: 68TH IEEE VEHICULAR TECHNOLOGY CONFERENCE, FALL 2008, 2008, 1872-1876 p.Conference paper (Refereed)
    Abstract [en]

    A joint adaptive power and adaptive rate (APAR) control algorithm for OFDM systems that aims at sum-rate maximization, subject to certain power and rate constraints, is presented in this paper. In the basic optimization framework, the overall system throughput is the main objective, but as such it lacks user fairness consideration. Two scheduling schemes that allow adjusting the trade-off between fairness and throughput are proposed and combined with the APAR scheme for fairness enhancement. Simulation results show that enhanced system performance and balanced efficiency-fairness trade-off can be achieved by the proposed schemes in downlink.

  • 2952.
    Xie, Tian
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Knowledge discovery and machinelearning for capacity optimizationof Automatic Milking RotarySystem2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Dairy farming as one part of agriculture has thousands of year’s history. The increasingdemands of dairy products and the rapid development of technology bring dairyfarming tremendous changes. Started by first hand milking, dairy farming goes throughvacuum bucket milking, pipeline milking, and now parlors milking. The automatic andtechnical milking system provided farmer with high-efficiency milking, effective herdmanagement and above all booming income.DeLaval Automatic Milking Rotary (AMRTM) is the world’s leading automatic milkingrotary system. It presents an ultimate combination of technology and machinerywhich brings dairy farming with significant benefits. AMRTM technical milking capacityis 90 cows per hour. However, constrained by farm management, cow’s condition andsystem configuration, the actual capacity is lower than technical value. In this thesis, anoptimization system is designed to analyze and improve AMRTM performance. The researchis focusing on cow behavior and AMRTM robot timeout. Through applying knowledgediscover from database (KDD), building machine learning cow behavior predictionsystem and developing modeling methods for system simulation, the optimizing solutionsare proposed and validated.

  • 2953.
    Xing, Hanwen
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Liu, Xin
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    A Lithium-ion Battery Charger2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

       Nowadays personal small electronic devices like cellphones are more and more popular, but the various batteries in need of charging become a problem. This thesis aims to explain a Lithium-ion charger which can control the current and voltage so that it can charge most kinds of popular batteries. More specifically, Li-ion battery charging is presented. The charging circuit design, simulation and the measurements will also be included.

  • 2954. Xinyu, Gu
    et al.
    Zhang, Zhang
    Grant, Stephen
    Wigren, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Johansson, Niklas
    Kangas, Ari
    Load control for multi-stage interference cancellation2012In: Proc. 23rd International Symposium on Personal, Indoor, and Mobile Radio Communications, Piscataway, NJ: IEEE, 2012, 339-344 p.Conference paper (Refereed)
  • 2955. Xiong, Junjie
    et al.
    Ngai, Edith C.-H.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Zhou, Yangfan
    Lyu, Michael R.
    RealProct: Reliable protocol conformance testing with real nodes for wireless sensor networks2011In: Proc. 10th International Conference on Trust, Security and Privacy in Computing and Communications, IEEE Computer Society, 2011Conference paper (Refereed)
  • 2956. Xiong, M.
    et al.
    Ozolins, O.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ding, Y.
    Huang, B.
    An, Y.
    Ou, H.
    Peucheret, C.
    Zhang, X.
    41.6 Gb/s RZ-DPSK to NRZ-DPSK format conversion in a microring resonator2012In: 2012 17th Opto-Electronics and Communications Conference, 2012, 891-892 p.Conference paper (Refereed)
    Abstract [en]

    RZ-DPSK to NRZ-DPSK format conversion in a silicon microring resonator is demonstrated experimentally for the first time at 41.6 Gb/s. The converted signal eye diagrams and bit-error-rate measurements show the good performance of the scheme.

  • 2957. Xiong, Q.
    et al.
    Lu, Zhonghai
    KTH, School of Information and Communication Technology (ICT), Electronics and Embedded Systems.
    Wu, F.
    Xie, C.
    Real-time analysis for wormhole NoC: Revisited and revised2016In: Proceedings of the ACM Great Lakes Symposium on VLSI, GLSVLSI, Association for Computing Machinery (ACM), 2016, 75-80 p.Conference paper (Refereed)
    Abstract [en]

    The network delay upper-bound analysis problem is of fundamental importance to real-time applications in Network-on-Chip (NoC). In the paper, we revisit a state-of-the-art analysis model for real-time communication in wormhole NoC with priority-based preemptive arbitration and show that the model may provide pessimistic or even incorrect network delay upper-bound. We then propose a revised analysis model to correct the flaws in the previous model by further classifying indirect interference as upstream and downstream indirect interferences according to the relative positions of traffic flows and taking buffer influence into consideration. Simulated evaluations show that our model provides tighter and correct network delay upper-bound compared with the state-of-the-art model.

  • 2958.
    Xiong, Xuelin
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    SCTP and Diameter Parameters for High Availability in LTE Roaming2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today mobile network operators utilize IP Packet exchange (IPX) carriers to interconnect their networks with other operators. Mobile network operators are free to choose one IPX carrier for their data traffic and another for their control traffic. This thesis examines the case of control traffic, specifically Stream Control Transmission Protocol (SCTP) carrying Diameter protocol traffic arising from users roaming from their home Long Term Evolution (LTE) network to another operator’s LTE network.

    The thesis project aims to identify a set of SCTP parameter configurations that can provide improved application/service level availability between two Diameter nodes in different network connectivity environments, specifically for IPX carriers who are Diameter service providers. These service providers provide Diameter connectivity for their customers who are mobile network operators. These mobile network operators in turn provide LTE roaming services to their customers.

    Unfortunately, applying the ‘One size fits all’ configuration recommendations given in the SCTP documentation is unsuitable for different network environments. In addition, the amount of Diameter signaling traffic is growing at a very rapid rate. Therefore, it is valuable to identify suitable parameter selection criteria for Diameter service providers to ensure 100% Diameter connectivity reliability for their customers. In this thesis project, author investigated how tuning SCTP parameter values affect Diameter message transmission in terms of Round Trip Delay and identified its determining parameters for packet loss recovery performance. Both IPX carriers and mobile network operators may use these values as reference when attempting to ensure high availability of Diameter transmissions under reliable, semi reliable, and unreliable network transport conditions.

  • 2959.
    Xiong, Ziyi
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Socio-economic Impact of Fiber to the Home in Sweden2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fiber-to-the-Home (FTTH) has been talked about since the introduction of fiberin the 1970s. It is nowadays shaping up to be the foundation of our newdigital society, bringing economic prosperity and a multitude of business,social, and entertainment opportunities to its users. The increased consumerdemand for high-speed network accessibility is being taken more and moreseriously and a fiber-based network is able to cope with these growing demandsdue to its wide bandwidth and reliability. Today there is a practical need forquantitative analysis regarding the socio-economic impacts of fiber-basedaccess networks. This analysis could be used as an indicator/reference for allthe stakeholder entities as they consider future investments anddevelopments. Sweden is a suitable target country for this analysis since ithas adopted fiber for some years and the benefits that FTTH has brought seemto already be tangible.

    The primary value of this thesis lies ininvestigation of its quantified evidence of the socio-economic impacts of FTTHdeployment in Sweden. This has been achieved based on data from the SwedishPost and Telecommunications Authority (PTS), Statistics Sweden (SCB), previousrelated studies, and information collected on-line from operators involved inthe fiber market, along with empirical analysis based on multivariateregression models.

    The results of the study show that fiber penetrationhas had a significant impact on the population’s evolution, specially the netamount of migration into a municipality, which indicates the attractiveness ofmunicipalities per se. It is therefore reasonable to suggest that localgovernment and local authorities take fiber deployment into consideration, ifthey want to attract people to stay for further local development. The studyalso analyzed the competition in fiber-based open networks and the prices ofsubscribing for 10/10 Mbps symmetrical Internet Service. Study findingsrevealed that networks with multiple competing service providers have a widerrange of services and a lower price: the more ISPs competing in a fibernetwork, the lower consumer prices. Specifically, for each new serviceprovider present in the network, there will be 5 SEK per month decrease of theaverage price of the Internet services, and an approximately 7 SEK per monthreduction in the lowest price.

    Nevertheless, a number of socio-economicimpacts remain unquantifiable as of the current time and due to the limitedavailable data. It is recommended to incorporate more socio-economic effectsin future research in order to draw a more complete picture for all theinterested sectors, and to supplement the data with recent figures for 2012and 2013.

  • 2960.
    Xu, Bingyu
    et al.
    Queen Mary University of London, London, United Kingdom.
    Chen, Yue
    Queen Mary University of London, London, United Kingdom.
    Requena Carrión, Jesús
    Queen Mary University of London, London, United Kingdom.
    Loo, Jonathan
    Middlesex University, London, United Kingdom.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Energy-aware Power Control in Energy Cooperation Aided Millimeter Wave Cellular Networks with Renewable Energy Resources2016In: IEEE Access, E-ISSN 2169-3536, Vol. 5, 432-442 p.Article in journal (Refereed)
    Abstract [en]

    Increased energy consumption becomes a major issue in 5G cellular networks, which inspires the network operators to deploy renewable energy sources. However, due to the fluctuating nature of renewable energy sources, the energy harvested by base stations (BSs) may not fit for their load conditions. The transmit power of the BS needs to be redesigned again. Hence, this paper considers power control in energy cooperation enabled millimeter wave (mmWave) networks, to alleviate the harvested energy imbalance problem and reduce the energy waste. Each BS is solely powered by renewable energy sources and the harvested energy is allowed to be transferred between BSs. Each BS needs to determine whether the energy should be stored in the battery or transferred to others at each time slot. In this work, power control is formulated as a stochastic optimization problem, aiming at maximizing the time average network utility while keeping the network stable. An online algorithm called Dynamic Energy-aware Power Allocation (DEPA) is proposed based on Lyapunov optimization, which does not need to acquire any statistical knowledge of channels and traffic arrivals. Simulation results show that compared with the power control scheme without energy cooperation, the proposed algorithm with energy cooperation can achieve higher network sum rate while reducing the delay and the required battery capacity.

  • 2961. Xu, Gang
    et al.
    Ngai, Edith C.-H.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Liu, Jiangchuan
    Information-centric collaborative data collection for mobile devices in wireless sensor networks2014In: Proc. International Conference on Communications: ICC 2014, IEEE Communications Society, 2014, 36-41 p.Conference paper (Refereed)
  • 2962.
    Xu, Jie
    et al.
    University of Science and Technology of China.
    Qiu, Ling
    University of Science and Technology of China.
    ur Rehman Ahsin, Tafzeel
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Ben Slimane, Slimane
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Scheduling, Pairing and Ordering in the Network Coded Uplink Multiuser MIMO Relay Channels2010In: 2010 IEEE 71ST VEHICULAR TECHNOLOGY CONFERENCE, 2010Conference paper (Refereed)
    Abstract [en]

    Network coded multiuser uplink MIMO channels have been discussed in this paper. A three slots transmission is considered here and spatial division multiple access (SDMA) has been employed to serve multiuser simultaneously. Minimum mean-square-error successive interference cancellation (MMSE-SIC) is applied in the first two slots and singular value decomposition (SVD) is applied for the third slots. In order to get the optimal performance, user scheduling, decoding ordering and user pairing need to be considered. However, the optimal exhaust searching algorithm is too complex to implement. We propose a low complexity scheme to solve this problem and the simulation results show the performance gain. The proposed scheme is promising in the real systems.

  • 2963.
    Xu, Tianhua
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Jacobsen, G.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Li, J.
    Wang, Ke
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics (Closed 20120101), Optics (Closed 20120101).
    Friberg, Ari T.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Variable-step-size LMS adaptive filter for digital chromatic dispersion compensation in PDM-QPSK coherent transmission system2009In: 2009 International Conference on Optical Instruments and Technology: Optical Systems and Modern Optoelectronic Instruments, SPIE - International Society for Optical Engineering, 2009, 75062I- p.Conference paper (Refereed)
    Abstract [en]

    High bit rates optical communication systems pose the challenge of their tolerance to linear and nonlinear fiber impairments. Digital filters in coherent optical receivers can be used to mitigate the chromatic dispersion entirely in the optical transmission system. In this paper, the least mean square adaptive filter has been developed for chromatic equalization in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying coherent optical transmission system established on the VPIphotonics simulation platform. It is found that the chromatic dispersion equalization shows a better performance when a smaller step size is used. However, the smaller step size in least mean square filter will lead to a slower iterative operation to achieve the guaranteed convergence. In order to solve this contradiction, an adaptive filter employing variable-step-size least mean square algorithm is proposed to compensate the chromatic dispersion in the 112-Gbit/s coherent communication system. The variable-step-size least mean square filter could make a compromise and optimization between the chromatic dispersion equalization performance and the algorithm converging speed. Meanwhile, the required tap number and the converged tap weights distribution of the variable-step-size least mean square filter for a certain fiber chromatic dispersion are analyzed and discussed in the investigation of the filter feature.

  • 2964.
    Xu, Yuzhe
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Real Time Scheduling in LTE for Smart Grids2012In: 5th International Symposium on Communications Control and Signal Processing, ISCCSP 2012, IEEE , 2012, 1-6 p.Conference paper (Refereed)
    Abstract [en]

    The latest wireless network, 3GPP Long Term Evolution (LTE), is considered to be a promising solution for smart grids because it provides both low latency and large bandwidth. However, LTE was not originally intended for smart grids applications, where data generated by the grid have specific delay requirements that are different from traditional data or voice communications. In this paper, the specific requirements imposed by a smart grids on the LTE communication infrastructure is first determined. The latency offered by the LTE network to smart grids components is investigated and an empirical mathematical model of the distribution of the latency is established. It is shown by experimental results that with the current LTE up-link scheduler, smart grid latency requirements are not always satisfied and that only a limited number of components can be accommodated. To overcome such a deficiency, a new scheduler of the LTE medium access control is proposed for smart grids. The scheduler is based on a mathematical linear optimization problem that considers simultaneously both the smart grid components and common user equipments. An algorithm for the solution to such a problem is derived based on a theoretical analysis. Simulation results based on this new scheduler illustrate the analysis. It is concluded that LTE can be effectively used in smart grids if new schedulers are employed for improving latency.

  • 2965.
    Xu, Yuzhe
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Hossein, Shokri-Ghadikolaei
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Distributed Association and Relaying in Millimeter Wave NetworksIn: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248Article in journal (Refereed)
  • 2966.
    Xu, Yuzhe
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Hossein, Shokri-Ghadikolaei
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Dynamic Distributed Association with Fairness in Millimeter Wave NetworksManuscript (preprint) (Other academic)
  • 2967. Xu, Z.
    et al.
    Archambault, E.
    Tremblay, C.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Belanger, M. P.
    Littlewood, P.
    1+1 dedicated optical-layer protection strategy for filterless optical networks2014In: IEEE Communications Letters, ISSN 1089-7798, Vol. 18, no 1, 98-101 p.Article in journal (Refereed)
    Abstract [en]

    We propose a dedicated optical-layer protection strategy for filterless optical networks offering a 100% protection ratio by introducing a limited number of wavelength selective components at selected intermediate nodes. A comparison with conventional active photonic switching networks is presented. The results show that the proposed 1+1 protection for filterless networks exhibits a clear cost advantage at similar wavelength usage compared to active switching solutions.

  • 2968.
    Yaghoubi, Forough
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Agile, Resilient and Cost-efficient Mobile Backhaul Networks2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The exponentially increasing traffic demand for mobile services requires innovative solutions in both access and backhaul segments of 5th generation (5G) mobile networks. Although, heterogeneous networks (HetNets) are a promising solution for the wireless access, the backhaul segment has received considerably less attention and falls short in meeting the stringent requirements of 5G in terms of capacity and availability.

    HetNets together with mobility requirements motivate the use of microwave backhauling that supports fiber-like capacity with millimeter-wave communications. However, higher carrier frequencies are subject to weather disturbances like rain that may substantially degrade the network throughput. To mitigate this effect, we develop a fast and accurate rain detection algorithm that triggers a network-layer strategy, i.e., rerouting. The results show that with small detection error the network throughput increases while posing small overhead on the network.

    The rain impact can be alleviated by centralized rerouting under the software defined networking paradigm. However, careless reconfiguration may impose inconsistency that leads to a significant temporary congestion and limits the gain of rerouting. We propose a consistency-aware rerouting framework by considering the cost of reconfiguration. At each time, the centralized controller may either take a rerouting or no-rerouting decision in order to minimize the total data loss. We use a predictive control algorithm to provide such an online sequence of decisions. Compared to the regular rerouting, our proposed approach reduces the throughput loss and substantially decreases the number of reconfigurations.

    In the thesis we also study which backhaul option is the best from a techno-economic perspective. We develop a comprehensive framework to calculate the total cost of ownership of the backhaul segment and analyze the profitability in terms of cash flow and net present value. The results highlight the importance of selecting proper backhaul solution to increase profitability.

  • 2969.
    Yaghoubi, Forough
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Furdek, Marija
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Rostami, Ahmad
    Ericsson AB.
    Öhlén, Peter
    Ericsson AB.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Consistency-aware Weather Disruption-tolerant Routing in SDNbased Wireless Mesh Networks2017In: IEEE TNSM Special Issue on Advances in Management of Softwarized NetworksArticle in journal (Other academic)
    Abstract [en]

    Although, wireless solutions continue to be a dominant enabling technology in the future backhaul  segment, they are susceptible to weather disturbances that may substantially degrade network throughput, or delay, compromising the 5G requirements.  These  effects  can  be  alleviated  by centralized rerouting realized by software defined networking (SDN) architecture. However, careless frequent reconfigurations may lead to inconsistencies in network states due to asynchrony between different switches, which may create  congestion and limit the gain of frequent rerouting.  In  this  paper, we focus on the rerouting process during rain disturbance considering the minimum total congestion imposed  during  the  update  of  routing  tables as a switching cost. At each time sample, the central controller has the possibility to adopt the optimal routes at a switching cost or to keep using previous routes at the expense of a throughput loss due to route sub- optimality. To find optimal solutions with minimal data loss in a static scenario, we formulate a dynamic programming problem that utilizes perfect knowledge of the rain attenuation for the whole rain period (off-line policy with full knowledge). For dynamic scenarios where the future rain attenuation data cannot be known, we propose an online consistency-aware rerouting algorithm, called optimal control action with prediction (OCAP), which uses the temporal correlation of rain fading to estimate the future rain attenuation. Simulation results on synthetic and real networks validate the efficiency of our OCAP algorithm, substantially reducing congestion and increasing network throughput with a fewer number of rerouting actions compared to benchmarks approaches.

  • 2970.
    Yaghoubi, Forough
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Mahloo, Mozghan
    Ericsson AB.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Monti, Paolo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Farias, Fabricio de Souza
    Universidade Federal do Pará.
    Costa, João Crisóstomo Weyl Albuquerque
    Universidade Federal do Pará.
    A Techno-Economic Framework for 5G Transport Networks2017Article in journal (Other academic)
    Abstract [en]

    Wireless heterogeneous networks (HetNets) are a cost- and an energy-efficient alternative to provide high capacity to end users in the future 5G communication systems. However, the transport segment of a radio access network (RAN) poses a big challenge in terms of cost and energy consumption. In fact, if not planned properly its resulting high cost might limit the benefits of using small cells and impact the revenues of mobile network operators. Therefore, it is essential to be able to properly assess the economic viability of different transport techonolgies as well as their impact on the cost and profitability of a HetNets deployment (i.e., RAN + transport).

    This paper first presents a general and comprehensive techno-economic framework able to assess not only the total cost of ownership (TCO) but also the business viability of a HetNets deployment. It then applies it to the specific case study of a backhaul-based transport segment. In the evaluation work two technology options for the transport network are considered (i.e., microwave and fiber) assuming both a homogeneous (i.e., macro cells only) and a HetNet deployments. Our results demonstrate the importance of selecting the right technology and deployment strategy in order not to impact the economic benefits of a HetNet deployment. Moreover, the results also reveal that a deployment solution with the lowest TCO does not always lead to the highest profit.  

  • 2971.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Multi Detector Fusion of Dynamic TOA hstimation using Kalman Filter2016In: 2016 IEEE International Conference on Communications (ICC), Institute of Electrical and Electronics Engineers (IEEE), 2016Conference paper (Refereed)
    Abstract [en]

    In this paper we propose fusion of dynamic time of arrival (TOA) from multiple low complexity detectors like energy detectors operating at sub-Nyquist rate through Kalman filtering. We show that by having a multi-channel sub-Nyquist receiver with each channel having an energy detector can match the performance of a single channel digital receiver with matched filter. We derive analytical expression for number of sub-Nyquist energy detector channels needed to achieve the performance of digital implementation with matched filter and demonstrate in simulation the validity of our analytical approach. Results indicate that number of energy detectors needed will he high at low SNRs and converge to a constant number as the SNR increases. We also study the performance of the proposed strategy using IEEE 802.15.4a CM1 multipath channel model and show in simulation that two sub-Nyquist detectors are sufficient to match the performance of digital matched filter.

  • 2972.
    Yalew, Sileshi Demesie
    et al.
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS. Universidade de Lisboa, Portugal.
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Correia, Miguel
    Universidade de Lisboa, Portugal.
    Light-SPD: a platform to prototype secure mobile applications2016In: Proceedings of the 1st ACM Workshop on Privacy-Aware Mobile Computing (PAMCO '16), New York, NY, USA: Association for Computing Machinery (ACM), 2016, 11-20 p.Conference paper (Refereed)
    Abstract [en]

    Securely storing sensitive personal data is critical for protecting privacy. Currently, many persons use smartphones to store their private data. However, smartphones suffer from many security issues. To overcome this situation, the PCAS project is designing a secure personal storage device called the Secure Portable Device (SPD), to be attached to a smartphone for securely storing sensitive personal data. However, this device is unavailable, closed, and expensive to deploy for prototyping applications. We propose a platform that emulates the SPD and the smartphone using a board with an ARM processor with the TrustZone security extension. This platform is open, inexpensive, and secure. A payment application is used as an example to show the platform's capabilities. As a proof-of-concept, we implemented this platform and provide a performance evaluation using a i.MX53 board.

  • 2973. Yang, B.
    et al.
    He, H.
    Hu, Xiaoming
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Detecting community structure in networks via consensus dynamics and spatial transformation2017In: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 483, 156-170 p.Article in journal (Refereed)
    Abstract [en]

    We present a novel clustering algorithm for community detection, based on the dynamics towards consensus and spatial transformation. The community detection problem is translated to a clustering problem in the N-dimensional Euclidean space by three stages: (1) the dynamics running on a network is emulated to a procedure of gas diffusion in a finite space; (2) the pressure distribution vectors are used to describe the influence that each node exerts on the whole network; (3) the similarity measures between two nodes are quantified in the N-dimensional Euclidean space by k-Nearest Neighbors method. After such steps, we could merge clusters according to their similarity distances and show the community structure of a network by a hierarchical clustering tree. Tests on several benchmark networks are presented and the results show the effectiveness and reliability of our algorithm.

  • 2974. Yang, Bo
    et al.
    Shen, Yanyan
    Johansson, Mikael
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Guan, Xinping
    Threshold-based Multichannel Access with Energy Constraint2010In: 2010 IEEE International Conference on Communications, 2010Conference paper (Refereed)
    Abstract [en]

    This paper considers multiaccess control for the uplink in orthogonal-frequency-division-multiple-access (OFDMA) wireless networks. To avoid extensive information exchange with the access point in centralized approaches, we propose a distributed threshold-based scheme, where each user accesses multiple channels simultaneously based on a comparison between measured channel gains and a channel gain threshold. Each user will adapts its channel gain threshold based on local measurements of collision on each channel and the energy consumption for channel contention. The problem is formulated as a constrained non-cooperative game. We show existence and uniqueness of the Nash equilibrium. A gradient-based algorithm is proposed to update the channel gain threshold. Furthermore, the convergence of this algorithm is proved. In addition, for heterogeneous systems, our proposed scheme can maintain multiuser diversity gains considering the time-varying channel gain and energy consumption. Compared with peer distributed OFDMA schemes and random channel selection algorithms, our proposed schemes reduce overhead and achieve a higher throughput.

  • 2975.
    Yang, Dekun
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Investigation of a new integration test environment: Facilitating offline debugging of Hardware-in-the-Loop2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Advanced automatic testing is very important in development and research within the vehicle industry. Hardware-in-the-loop (HIL) systems give the ability to validate Electronic Control Units (ECUs) based on software simulation without gathering all of the physical hardware. This enables testing by providing inputs and examining the corresponding outputs of the ECUs in a simpler and safer way than in traditional physical testing. HIL offers the advantage that we can verify and validate the functions of ECUs prior to full-scale hardware production.

    On the contrary, because HIL systems are normally released as general-purpose test beds, it takes time to embed them into the current system. Additionally, the question of how to fill the gap between the HIL and the test environment is even more critical when the test bed is expected to be used for a long period of time without modifications. Furthermore, HIL systems are precious. It is not practical and will be considered as a waste of resource if it is used exclusively by testers. Scania’s RESI group uses Client-Server architecture to make it more flexible. The HIL system is hosted at server side while the testers operate it at client side. This architecture enables different implementations of client and server as long as a same protocol is applied, but this still does not solve the problem that the HIL is not always accessible when the testers want to debug their scripts. The testers want to find a solution to achieve this goal offline (without servers).

    To solve the problem, we first investigated which programming languages are used in the industry. Without doubt, there is no dominant language that ideally suits all situations, so secondly, we developed a new test environment. The new environment including “Dummy Mode” and “Mat Mode” is able to provide script validation service on basic and logic levels without servers. The result shows the Dummy mode is able to reach a higher detection rate (99.3%) on simple errors comparing to the current environment (81.3%). By reproducing and reusing the result of HIL system, Mat mode is able to identify logic errors and provide better assistance when the logic errors are found. In general, the proposed environment is able to show a better way of using HIL which makes the whole system more efficient and productive.

  • 2976.
    Yang, Guang
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Interference statistics of regular ring-structured networks with 60 GHz directional antennas2017In: 2017 IEEE International Conference on Communications, Institute of Electrical and Electronics Engineers (IEEE), 2017, 7996400Conference paper (Refereed)
    Abstract [en]

    To overcome the severe path loss and provide higher spectral efficiency for 60 GHz wireless communications, highly directional antennas, which indicate high antenna gains, are widely employed. In this work, we focus on the trade-off between the beamwidth of directional antennas and the interference produced by random concurrent transmissions, in terms of two important statistics, i.e., the expectation and variance. A specific regular network is considered, which consists of multi-layer rings, and a typical receiver with a fixed orientation is placed in the network center.We derive closed-form expressions of interference statistics associated with the beamwidth, which are followed by upper and lower bounds. In addition, we demonstrate that the performance gain provided by directional antennas approximately grows in the fashion of the reciprocal of beamwidth, and an approximation for the expectation of signal-to-interference-and-noise ratio (SINR) is also presented. Numerical results show that, analytic expressions coincide with simulations, and derived bounds are valid. The benefits of utilizing directional antennas are quantified and verified. Furthermore, the impacts of the factors, such as path loss exponent and side-lobe gain, are also studied, comprehensively.

  • 2977.
    Yang, Guang
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Gross, James
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Al-Zubaidy, Hussein
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Huang, Yongming
    Delay and Backlog Analysis for 60 GHz Wireless Networks2016In: 2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2016, 7841725Conference paper (Refereed)
    Abstract [en]

    To meet the ever-increasing demands on higher throughput and better network delay performance, 60 GHZ networking is proposed as a promising solution for the next generation of wireless communications. To successfully deploy such networks, its important to understand their performance first. However, due to the unique fading characteristic of the 60 GHz channel, the characterization of the corresponding service process, offered by the channel, using the conventional methodologies may not be tractable. In this work, we provide an alternative approach to derive a closed-form expression that characterizes the cumulative service process of the 60 GHz channel in terms of the moment generating function (MGF) of its instantaneous channel capacity. We then use this expression to derive probabilistic upper bounds on the backlog and delay that are experienced by a flow traversing this network, using results from the MGF-based network calculus. The computed bounds are validated using simulation. We provide numerical results for different networking scenarios and for different traffic and channel parameters and we show that the 60 GHz wireless network is capable of satisfying stringent quality-of-Service (QoS) requirements, in terms of network delay and reliability. With this analysis approach at hand, a larger scale 60 GHz network design and optimization is possible.

  • 2978.
    Yang Lin, Shih
    et al.
    Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE).
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Englund, Cristofer
    Viktoria Swedish ICT, Gothenburg, Sweden.
    Chen, Lei
    Viktoria Swedish ICT, Gothenburg, Sweden.
    Poster: Adaptive Wavelength Adjustment (AWLA) for Cooperative Speed Harmonization2014In: 2014 IEEE Vehicular Networking Conference (VNC) / [ed] Falko Dressler, Onur Altintas, Suman Banerjee, Björn Scheuermann & David Eckhoff, Piscataway, NJ: IEEE Press, 2014, 113-114 p.Conference paper (Refereed)
    Abstract [en]

    Traffic merge on express-ways creates bottlenecks for traffic flow that potentially lead to traffic jams, especially in dense traffic. Cooperative speed harmonization (CSH), where vehicles are grouped and associated to virtual speed waves for group-wise joining at intersections, is proven to be efficient for on-ramp traffic merge. Based on CSH and considering variations of traffic density from joining roads, an adaptive wavelength adjustment (AWLA) mechanism is proposed in this paper. AWLA extends CSH by dynamically adjusting the length of segments in virtual waves according to the traffic densities of the joining roads. Therefore, roads with denser traffic may have larger segments to carry more vehicles through the intersection, which may improve the overall performance. Simulation results have shown that AWLA can achieve lower CO2 emissions and shorter travel time compared to CSH with static segment settings.

  • 2979.
    Yang, Xi
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    The Use of One-Time Password and RADIUS Authentication in a GSS-API Architecture2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Generic Security Service Application Program Interface (GSS-API) is an architecture that facilitates applications using distributed security services in a mechanism-independent fashion. GSS-API is supported by various underlying mechanisms and technologies such as Kerberos version 5 and public-key technologies. However, no one-time password based GSS-API mechanism existed.

    This thesis focuses on an investigation using one-time passwords together with RADIUS authentication as a protection facility for a GSS-API mechanism. This thesis presents a security architecture using one-time passwords to establish a GSS-API security context between two communicating peers.

    The proposed one-time password based GSS-API mechanism could be used to enhance the security of user authentication. Moreover, the mechanism can greatly facilitate static-password based system’s transition to stronger authentication.

  • 2980.
    Yang, Yanpeng
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    A study on the deployment and cooperative operation of ultra-dense networks2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The traffic volume in wireless communication has grown dramatically in the last decade and is predicted to keep increasing in the future. In this thesis, we focus on the densification dimension for capacity improvement, which has been proved to be the most effective in the past. The current gain of network densification mainly comes from cell splitting, thereby serving more user equipments (UEs) simultaneously. This trend will decelerate as base station (BS) density gets closer to or even surpass UE density which forms an ultra-dense network (UDN). Thus, it is crucial to understand the behavior of ultra-densification for future network provisioning.

     

    We start from comparing the effectiveness of densification with spectrum expansion and multi-antenna systems. Our findings show that deploying more BSs provides a substantial gain in sparse network but the gain decreases progressively in a UDN. The diminishing gain appears in a UDN make us curious to know if there exists a terminal on the way of densification. Such uncertainty leads to the study on the asymptotic behavior of densification. We incorporate a sophisticated bounded dual-slope path loss model and practical UE densities in our analysis. By using stochastic geometry, we derive the expressions and prove the convergence of the coverage probability of a typical UE and network area spectral efficiency (ASE). Considering the large portion of dormant BSs in a UDN, it is an interesting question whether we can utilize these dormant BSs to improve system performance is an interesting question. To this end, we employ joint transmission (JT) techniques into a UDN. Two types of cooperation schemes are investigated: non-coherent JT and coherent JT depending on the availability of channel state information (CSI). Our results reveal that non-coherent JT is not beneficial in a UDN while coherent JT are able to increase UE spectral efficiency (SE) depending on the environmental parameters.

  • 2981.
    Yang, Yanpeng
    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.
    Park, J.
    Sung, Ki Won
    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.
    On the asymptotic behavior of ultra-densification under a bounded dual-slope path loss model2017In: European Wireless 2017 - 23rd European Wireless Conference, Institute of Electrical and Electronics Engineers (IEEE), 2017, 8011320Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the impact of network densification on the performance in terms of downlink signal-to-interference (SIR) coverage probability and network area spectral efficiency (ASE). A sophisticated bounded dual-slope path loss model and practical user equipment (UE) densities are incorporated in the analysis, which have never been jointly considered before. By using stochastic geometry, we derive an integral expression along with closed-form bounds of the coverage probability and ASE, validated by simulation results. Through these, we provide the asymptotic behavior of ultra-densification. The coverage probability and ASE have non-zero convergence in asymptotic regions unless UE density goes to infinity (full load). Meanwhile, the effect of UE density on the coverage probability is analyzed. The coverage probability will reveal an U-shape for large UE densities due to interference fall into the near-field, but it will keep increasing for low UE densites. Furthermore, our results indicate that the performance is overestimated without applying the bounded dual-slope path loss model. The derived expressions and results in this work pave the way for future network provisioning.

  • 2982.
    Yang, Yanpeng
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Park, Jihong
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    On the Asymptotic Behavior of Ultra-Densificationunder a Bounded Dual-Slope Path Loss ModelManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, we investigate the impact of networkdensification on the performance in terms of downlink signal-tointerference(SIR) coverage probability and network area spectralefficiency (ASE). A sophisticated bounded dual-slope path lossmodel and practical UE densities are incorporated in the analysis.By using stochastic geometry, we derive an integral expressionalong with closed-form bounds of the coverage probability andASE, validated by simulation results. Through these, we providethe asymptotic behavior of ultra-densification. The coverageprobability and ASE have non-zero convergence in asymptoticregions unless UE density goes to infinity (full load). Meanwhile,the effect of UE density on the coverage probability is analyzed.The coverage probability will suffer from decreasing with largeUE densities due to interference fall into the near-field, but it willkeep increasing with lower UE densites. Furthermore, we showthe performance is overestimated without applying the boundeddual-slope path loss model. Our study can give insights on efficientnetwork provisioning in the future.

  • 2983.
    Yang, Yanpeng
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Shi, Lei
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Zander, Jens
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    On the Capacity of Wi-Fi System in TV White Space with Aggregate Interference Constraint2013In: Proceedings of the 2013 8th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCOM 2013, IEEE conference proceedings, 2013, 123-128 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a quantitative assessmentof the performance of a Wi-Fi like system in TV white space andcompare it with the traditional Wi-Fi system in the ISM band.Particular emphasis is given to the constraint on the aggregatesecondary interference on TV reception, which is regarded as thepremise of the link throughput analysis that followed. Numericalevaluation is performed over different scenarios where the TVreceive signal strength, number of unoccupied TV channels, userdensity are varied. Our results show that the primary interferenceconstraint has only significant impact on the secondary systemperformance in rural scenario with low TV receive signalstrength. In other cases, where higher transmit power does notguarantee better performance, the capacity of the system islimited by the secondary self-interference or collisions rather thanthe interference constraint. Therefore, efficient TV White Spaceutilization can be achieved by properly setting the secondarytransmit power adaptive to different environments.

  • 2984.
    Yang, Yanpeng
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Sung, Ki Won
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Park, Jihong
    Kim, Seong-Lyun
    Kim, Kwang Soon
    Cooperative Transmissions in Ultra-Dense Networks under a Bounded Dual-Slope Path Loss ModelManuscript (preprint) (Other academic)
    Abstract [en]

    In an Ultra-dense network (UDN) where there aremore base stations (BSs) than active users, it is possible thatmany BSs are instantaneously left idle. Thus, how to utilizethese dormant BSs by means of cooperative transmission is aninteresting question. In this paper, we investigate the performanceof a UDN with two types of cooperation schemes: non-coherentjoint transmission (JT) without channel state information (CSI)and coherent JT with full CSI knowledge. We consider a boundeddual-slope path loss model to describe UDN environments wherea user has several BSs in the near-field and the rest in thefar-field. Numerical results show that non-coherent JT cannotimprove the user spectral efficiency (SE) due to the simultaneousincrement in signal and interference powers. For coherent JT, theachievable SE gain depends on the range of near-field, the relativedensities of BSs and users, and the CSI accuracy. Finally, weassess the energy efficiency (EE) of cooperation in UDN. Despitecosting extra energy consumption, cooperation can still improveEE under certain conditions.

  • 2985.
    Yang, Zhe
    et al.
    Dept. of Signal Processing Processing, Blekinge Institute of Technology.
    Khamit, Saltanat
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Mohammed, A.
    Dept. of Signal Processing Processing, Blekinge Institute of Technology.
    Larson, Peter
    Strategoc Dev., Affärsverken Karlskrona AB.
    A Comparative Study on Business Models of Municipal WirelessCities in US and Sweden2008In: 3rd IEEE/IFIP International Workshop on Business-driven IT Management, 2008. BDIM 2008, IEEE conference proceedings, 2008, 116-117 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, we will explore the existing operational "business models" for municipal wireless networks in US and Sweden. Based on the current paradigms of the North-American public wireless networks, we will investigate an emerging wireless city concept in Sweden to analysis this new business concept in the existing field. We will look into the relationship of different actors in various business models of the wireless cities in our selected case studies. This paper will aim to demonstrate a number of key considerations when designing and managing the business model of Municipal wireless networks as business-driven and public utility-driven services.

  • 2986.
    Yanggratoke, Rerngvit
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Data-driven Performance Prediction and Resource Allocation for Cloud Services2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cloud services, which provide online entertainment, enterprise resource management, tax filing, etc., are becoming essential for consumers, businesses, and governments. The key functionalities of such services are provided by backend systems in data centers. This thesis focuses on three fundamental problems related to management of backend systems. We address these problems using data-driven approaches: triggering dynamic allocation by changes in the environment, obtaining configuration parameters from measurements, and learning from observations. 

    The first problem relates to resource allocation for large clouds with potentially hundreds of thousands of machines and services. We developed and evaluated a generic gossip protocol for distributed resource allocation. Extensive simulation studies suggest that the quality of the allocation is independent of the system size for the management objectives considered.

    The second problem focuses on performance modeling of a distributed key-value store, and we study specifically the Spotify backend for streaming music. We developed analytical models for system capacity under different data allocation policies and for response time distribution. We evaluated the models by comparing model predictions with measurements from our lab testbed and from the Spotify operational environment. We found the prediction error to be below 12% for all investigated scenarios.

    The third problem relates to real-time prediction of service metrics, which we address through statistical learning. Service metrics are learned from observing device and network statistics. We performed experiments on a server cluster running video streaming and key-value store services. We showed that feature set reduction significantly improves the prediction accuracy, while simultaneously reducing model computation time. Finally, we designed and implemented a real-time analytics engine, which produces model predictions through online learning.

  • 2987.
    Yanggratoke, Rerngvit
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture, Telecommunication Systems Laboratory, TSLab.
    GPU Network Processing2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Networking technology is connecting more and more people around the world. It has become an essential part of our daily life. For this connectivity to be seamless, networks need to be fast. Nonetheless, rapid growth in network traffic and variety of communication protocols overwhelms the Central Processing Units (CPUs) processing packets in the networks. Existing solutions to this problem such as ASIC, FPGA, NPU, and TOE are not cost effective and easy to manage because they require special hardware and custom configurations.

    This thesis approaches the problem differently by offloading the network processing to off-the-shelf Graphic Processing Units (GPUs). The thesis's primary goal is to find out how the GPUs should be used for the offloading. The thesis follows the case study approach and the selected case studies are layer 2 Bloom filter forwarding and flow lookup in Openflow switch. Implementation alternatives and evaluation methodology are proposed for both of the case studies. Then, the prototype implementation for comparing between traditional CPU-only and GPU-offloading approach is developed and evaluated.

    The primary findings from this work are criteria of network processing functions suitable for GPU offloading and tradeoffs involved. The criteria are no inter-packet dependency, similar processing flows for all packets, and within-packet parallel processing opportunity. This offloading trades higher latency and memory consumption for higher throughput.

  • 2988.
    Yanggratoke, Rerngvit
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Ahmed, Jawwad
    Ericsson Research, Sweden.
    Ardelius, John
    Swedish Institute of Computer Science (SICS), Sweden.
    Flinta, Christofer
    Ericsson Research, Sweden.
    Johnsson, Andreas
    Ericsson Research, Sweden.
    Gillblad, Daniel
    Swedish Institute of Computer Science (SICS), Sweden.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Predicting Real-time Service-level Metrics from Device Statistics2015In: IFIP/IEEE International Symposium on Integrated Network Management, IM 2015, Ottawa, Canada, IEEE Communications Society, 2015Conference paper (Refereed)
    Abstract [en]

    While real-time service assurance is critical for emerging telecom cloud services, understanding and predicting performance metrics for such services is hard. In this paper, we pursue an approach based upon statistical learning whereby the behavior of the target system is learned from observations. We use methods that learn from device statistics and predict metrics for services running on these devices. Specifically, we collect statistics from a Linux kernel of a server machine and predict client-side metrics for a video-streaming service (VLC). The fact that we collect thousands of kernel variables, while omitting service instrumentation, makes our approach service-independent and unique. While our current lab configuration is simple, our results, gained through extensive experimentation, prove the feasibility of accurately predicting client-side metrics, such as video frame rates and RTP packet rates, often within 10-15% error (NMAE), also under high computational load and across traces from different scenarios.

  • 2989.
    Yanggratoke, Rerngvit
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Ahmed, Jawwad
    Ardelius, John
    Flinta, Christofer
    Johnsson, Andreas
    Gillblad, Daniel
    Swedish Institute of Computer Science (SICS), Sweden.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Predicting Real-time Service-level Metrics from Device Statistics2014Report (Other academic)
    Abstract [en]

    While real-time service assurance is critical for emerging telecom cloud services, understanding and predicting performance metrics for such services is hard. In this paper, we pursue an approach based upon statistical learning whereby the behavior of the target system is learned from observations. We use methods that learn from device statistics and predict metrics for services running on these devices. Specifically, we collect statistics from a Linux kernel of a server machine and predict client-side metrics for a video-streaming service (VLC). The fact that we collect thousands of kernel variables, while omitting service instrumentation, makes our approach service-independent and unique. While our current lab configuration is simple, our results, gained through extensive experimentation, prove the feasibility of accurately predicting client-side metrics, such as video frame rates and RTP packet rates, often within 10-15% error (NMAE), also under high computational load and across traces from different scenarios.

  • 2990.
    Yanggratoke, Rerngvit
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Networks.
    Ahmed, Jawwad
    Ardelius, John
    Flinta, Christofer
    Johnsson, Andreas
    Gillblad, Daniel
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Predicting service metrics for cluster-based services using real-time analytics2015In: IFIP/IEEE 11th International Conference on Network and Service Management, CNSM 2015, Barcelona, Spain, November 9-13, 2015, IEEE conference proceedings, 2015Conference paper (Refereed)
    Abstract [en]

    Predicting the performance of cloud services is intrinsically hard. In this work, we pursue an approach based upon statistical learning, whereby the behaviour of a system is learned from observations. Specifically, our testbed implementation collects device statistics from a server cluster and uses a regression method that accurately predicts, in real-time, client-side service metrics for a video streaming service running on the cluster. The method is service-agnostic in the sense that it takes as input operating-systems statistics instead of service-level metrics. We show that feature set reduction significantly improves prediction accuracy in our case, while simultaneously reducing model computation time. We also discuss design and implementation of a real-time analytics engine, which processes streams of device statistics and service metrics from testbed sensors and produces model predictions through online learning.

  • 2991.
    Yanggratoke, Rerngvit
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Networks.
    Ahmed, Jawwad
    Ardelius, John
    Flinta, Christoffer
    Johnsson, Andreas
    Gillblad, Daniel
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    A service-agnostic method for predicting service metrics in real-timeManuscript (preprint) (Other academic)
    Abstract [en]

    We predict performance metrics of cloud services using statistical learning, whereby the behavior of a system is learned from observations. Specifically, we collect device and network statistics from a cloud testbed and apply regression methods to predict, in real-time, client-side service metrics for video streaming and key-value store services. Our method is service agnostic in the sense that it takes as input operating-systems and network statistics instead of service-specific metrics. We show that feature set reduction significantly improves the prediction accuracy in our case, while simultaneously reducing model computation time. We find that the prediction accuracy decreases when, instead of a single service, both services run on the same testbed simultaneously or when the network quality on the path between the server cluster and the client deteriorates. Finally, we discuss the design and implementation of a real-time analytics engine, which processes streams of device statistics and service metrics from testbed sensors and produces model predictions through online learning.

  • 2992.
    Yanggratoke, Rerngvit
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Azfar, Abdullah
    Marval, María José Peroza
    Ahmed, Sharjeel
    Delay Tolerant Network on Android Phones: Implementation Issues and Performance Measurements2011In: Journal of Communications, ISSN 1796-2021, Vol. 6, no 6, 477-484 p.Article in journal (Refereed)
    Abstract [en]

    Many regions of the world do not have access to the Internet due to lack of proper communication infrastructure. Delay Tolerant Network (DTN) provides communication in a challenging network condition such as high communication delay and intermittent connectivity. DTN is a promising solution to solve lack of connectivity problems in developing regions such as rural areas. DTN works in a store-and-forward approach, where the data is stored in a server and forwarded to a suitable carrier. The android phones can be made DTN capable to become a carrier for DTN bundles. Android phone is one of the front runners as the DTN carrier because of its portability and increasing popularity. In this paper, we have described theimplementation of DTN on Android phone and the performance measurements including DTN bandwidth and battery consumption.

  • 2993.
    Yanggratoke, Rerngvit
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Networks.
    El Hosary, Amira
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Networks.
    Selected Paper on Network and Cloud Analytics2016Report (Other academic)
    Abstract [en]

    This report reviews selected papers from the ones presented in the seminar on Network and Cloud Analytics since April 2015 till November 2015 (realm.sics.se). During this time period, the seminar discussed 43 papers that span different research disciplines, such as analytics for network management, network anomaly detection, large-scale machine learning, and learning under concept drift. From those papers, we select 13 papers that provide compelling contributions and possible extensions for future work. Additionally, we grouped the selected papers based on their problem area. For each selected paper, we identify the problem that the authors try to solve, major challenges that make the problem difficult, a proposed approach to solve the problem, and key contributions of the paper. Further, we show the limitations of the proposed method and suggest ideas for applying the paper to our research projects.

  • 2994.
    Yanggratoke, Rerngvit
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Kreitz, Gunnar
    Spotify.
    Goldmann, Mikael
    Spotify.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Networks.
    Predicting response times for the Spotify backend2012Report (Other academic)
    Abstract [en]

    We model and evaluate the performance of a distributed key-value storage system that is part of the Spotify backend. Spotify is an on-demand music streaming service, offering low-latency access to a library of over 16 million tracks and serving over 10 million users currently. We first present a simplified model of the Spotify storage architecture, in order to make its analysis feasible. We then introduce an analytical model for the distribution of the response time, a key metric in the Spotify service. We parameterize and validate the model using measurements from two different testbed configurations and from the operational Spotify infrastructure. We find that the model is accurate—measurements are within 11% of predictions—within the range of normal load patterns. We apply the model to what-if scenarios that are essential to capacity planning and robustness engineering. The main difference between our work and related research in storage system performance is that our model provides distributions of key system metrics, while related research generally gives only expectations, which is not sufficient in our case.

  • 2995.
    Yanggratoke, Rerngvit
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Kreitz, Gunnar
    KTH, School of Computer Science and Communication (CSC), Theoretical Computer Science, TCS. Spotify AB.
    Goldmann, Mikael
    Spotify AB.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fodor, Viktoria
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Networks.
    On the performance of the Spotify backend2013In: Journal of Network and Systems Management, ISSN 1064-7570, E-ISSN 1573-7705Article in journal (Refereed)
    Abstract [en]

    We model and evaluate the performance of a distributed key-value storage system that is part of the Spotify backend. Spotify is an on-demand music streaming service, offering low-latency access to a library of over 20 million tracks and serving over 20 million users currently. We first present a simplified model of the Spotify storage architecture, in order to make its analysis feasible. We then introduce an analytical model for the distribution of the response time, a key metric in the Spotify service. We parameterize and validate the model using measurements from two different testbed configurations and from the operational Spotify infrastructure. We find that the model is accurate---measurements are within 11% of predictions---within the range of normal load patterns.In addition, we model the capacity of the Spotify storage system under different object allocation policies and find that measurements on our testbed are within 9% of the model predictions. The model helps us justify the object allocation policy adopted for Spotify storage system.

  • 2996. Yasoubi, A.
    et al.
    Hojabr, R.
    Takshi, H.
    Modarressi, M.
    Daneshtalab, Masoud
    KTH, School of Information and Communication Technology (ICT), Electronics and Embedded Systems.
    CuPAN - high throughput on-chip interconnection for neural networks2015In: 22nd International Conference on Neural Information Processing, ICONIP 2015, Springer, 2015, 559-566 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a Custom Parallel Architecture for Neural networks (CuPAN). CuPAN consists of streamlined nodes that each node is able to integrate a single or a group of neurons. It relies on a high-throughput and low-cost Clos on-chip interconnection network in order to efficiently handle inter-neuron communication. We show that the similarity between the traffic pattern of neural networks (multicast-based multi-stage traffic) and topological characteristics of multi-stage interconnection networks (MINs) makes neural networks naturally suited to the MINs. The Clos network, as one of the most important classes of MINs, provide scalable low-cost interconnection fabric composed of several stages of switches to connect two groups of nodes and interestingly, can support multicast in an efficient manner. Our evaluation results show that CuPAN can manage the multicast-based traffic of neural networks better than the mesh-based topologies used in many parallel neural network implementations and gives lower average message latency, which directly translates to faster neural processing.

  • 2997.
    Yavari, Ali
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Measuring the Quality of Experience of Mobile Video StreamingManuscript (preprint) (Other academic)
    Abstract [en]

    In recent years the growing popularity of mobile phones with the ability of accessing the Internet has increased the usage of video streaming services on the mobile phone devices. These devices can access the Internet using different technologies like Wi-Fi, Bluetooth or Wide Area cellular accesses like GPRS, 3G or 4G. Video streaming services typically consume more data than other successful services like e-mails, photo sharing and web-browsing, and their performances are limited by the bandwidth and data rates that can be provided by current mobile networks. Resource limitations in mobile networks are typically translated into data starvation and interruptions in the video streaming playbacks, leading to low user satisfaction levels. In order to evaluate the users’ satisfaction of the mobile video streaming services, in current heterogeneous mobile networks, it is necessary to introduce techniques to measure the users’ video streaming quality of experience which relates to how users perceive the quality of video streaming playback. In this paper we present an overview of various techniques for measuring the users’ QoE of mobile video streaming service.

  • 2998.
    Yavari, Ali
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Network Efficient Resource Management for Mobile Video Streaming based on Quality of Experience2013In: 2013 International Conference on ICT Convergence (ICTC): , IEEE Communications Society, 2013, 654-659 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents a novel experimental approach to quantify the performances of Quality of Experience (QoE)- aware resource management scheme in mobile network. The main goal of this paper is to improve network efficiency by exploiting knowledge of QoE information associated with online video streaming services. The investigations considered in the paper are performed using an innovative test-bed, developed to assess network efficiency for the provision of online video services of different qualities. The QoE model used in the proposed QoEaware allocation scheme assumes a MOS-like grading function whose grades depend on both the duration of playtime interruption and the streaming video quality (resolution). The results show that the proposed resource management scheme can deliver more than 40 percent higher QoE to the users of the system as compared to current agnostic (not aware of QoE requirement and content characteristics) service models.

  • 2999.
    Yavari, Ali
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Lungaro, Pietro
    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.
    Segall, Zary
    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.
    Towards a Semantic-aware Location Positioning for Smart-phones2013In: 2013 Fifth International Conference on Ubiquitous and Future Networks (ICUFN), IEEE conference proceedings, 2013, 487-488 p.Conference paper (Refereed)
    Abstract [en]

    Location-aware services and applications have be- come quite popular in the daily life of mobile users. Global Positioning System (GPS) is available in almost all new smart- phones as a mature and accurate positioning technique. GPS as a satellite-based navigation system, determines the current location of users by receiving signals from satellites. Satellite signals cannot propagate properly inside the buildings, which makes it unusable for indoor positioning. In addition, GPS consumes too much energy to be useful for many applications on mobile phones. There are many proposed alternatives for GPS but they are not as accurate. Combination of those alternatives can improve the accuracy, but varies widely depending on the user behavior and environment. This paper presents a novel architecture for semantic-aware positioning that chooses the best positioning method(s) by exploiting the semantic knowledge. 

  • 3000.
    Yavari, Ali
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Martinez Ballesteros, Luis Guillermo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Quality of Experience-aware Resource Management for Mobile Video StreamingManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, we present a novel experimental approach to quantify the performances of Quality of Experience (QoE)-aware resource management scheme in mobile networks. The main goal of this paper is to improve network efficiency by exploiting in the resource management the knowledge of QoE information associated with online video streaming services. The investigations considered in the paper are performed using an innovative test-bed, developed to assess network efficiency, as well as the impact on the energy consumption at mobile terminal (MT), for the provision of online video services of different qualities. The QoE model used in the proposed QoE-aware allocation scheme assumes a MOS-like grading function whose grades depend on both the duration of playtime interruption and the video quality (resolution). The results show that the proposed resource management scheme can deliver more than 40 percent higher QoE and energy saving at mobile terminal between 12% to 15% to the users of the system as compared to current agnostic (not aware of QoE requirement and content characteristics) service models.

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