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  • 3501.
    Zhang, Ke
    et al.
    University of Electronic Science and Technology of China, Chengdu, China.
    Mao, Yuming
    University of Electronic Science and Technology of China, Chengdu, China.
    Leng, Supeng
    University of Electronic Science and Technology of China, Chengdu, China.
    Maharjan, Sabita
    Simula Research Laboratory, Fornebu, Norway & University of Oslo, Oslo, Norway.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Zhang, Yan
    University of Oslo, Oslo, Norway.
    Contract-theoretic Approach for Delay Constrained Offloading in Vehicular Edge Computing Networks2018In: Journal on spesial topics in mobile networks and applications, ISSN 1383-469X, E-ISSN 1572-8153Article in journal (Refereed)
    Abstract [en]

    Mobile Edge Computing (MEC) is a promising solution to improve vehicular services through offloading computation to cloud servers in close proximity to mobile vehicles. However, the self-interested nature together with the high mobility characteristic of the vehicles make the design of the computation offloading scheme a significant challenge. In this paper, we propose a new Vehicular Edge Computing (VEC) framework to model the computation offloading process of the mobile vehicles running on a bidirectional road. Based on this framework, we adopt a contract theoretic approach to design optimal offloading strategies for the VEC service provider, which maximize the revenue of the provider while enhancing the utilities of the vehicles. To further improve the utilization of the computing resources of the VEC servers, we incorporate task priority distinction as well as additional resource providing into the design of the offloading scheme, and propose an efficient VEC server selection and computing resource allocation algorithm. Numerical results indicate that our proposed schemes greatly enhance the revenue of the VEC provider, and concurrently improve the utilization of cloud computing resources.

  • 3502.
    Zhang, Ke
    et al.
    University of Electronic Science and Technology of China, Chengdu, China.
    Mao, Yuming
    University of Electronic Science and Technology of China, Chengdu, China.
    Leng, Supeng
    University of Electronic Science and Technology of China, Chengdu, China.
    Maharjan, Sabita
    Simula Research Laboratory, Oslo, Norway.
    Zhang, Yan
    Simula Research Laboratory, Oslo, Norway.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Jonsson, Magnus
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Incentive-Driven Energy Trading in the Smart Grid2016In: IEEE Access, E-ISSN 2169-3536, Vol. 4, p. 1243-1257, article id 7436757Article in journal (Refereed)
    Abstract [en]

    The smart grid is widely considered as an efficient and intelligent power system. With the aid of communication technologies, the smart grid can enhance the efficiency and reliability of the grid system through intelligent energy management. However, with the development of new energy sources, storage and transmission technologies together with the heterogeneous architecture of the grid network, several new features have been incorporated into the smart grid. These features make the energy trading more complex and pose a significant challenge on designing efficient trading schemes. Based on this motivation, in this paper, we present a comprehensive review of several typical economic incentive approaches adopted in the energy-trading control mechanisms. We focus on the technologies that address the challenges specific to the new features of the smart grid. Furthermore, we investigate the energy trading in a new cloud-based vehicle-to-vehicle energy exchange scenario. We propose an optimal contract-based electricity trading scheme, which efficiently increases the generated profit. © 2013 IEEE.

  • 3503.
    Zhang, Ke
    et al.
    School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu, China.
    Mao, Yuming
    School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu, China.
    Leng, Supeng
    School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu, China.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Zhang, Yan
    Simula Research Laboratory, Oslo, Norway.
    Delay constrained offloading for Mobile Edge Computing in cloud-enabled vehicular networks2016In: Proceedings of 2016 8th International Workshop on Resilient Networks Design and Modeling (RNDM) / [ed] Magnus Jonsson, Jacek Rak, Arun Somani, Dimitri Papadimitriou & Alexey Vinel, Piscataway: IEEE Press, 2016, p. 288-294Conference paper (Refereed)
    Abstract [en]

    Cloud-based vehicular networks is a new paradigm to improve the vehicular services through distributing computation tasks between remote clouds and local vehicular terminals. To further reduce the latency and the transmission cost of the computation offloading, we propose a cloud-based Mobile Edge Computing (MEC) offloading framework in vehicular networks. In the framework, efficient computation offloading strategies are designed through a contract theoretic approach. We obtain the optimal feasible contracts that maximize the benefit of the MEC service provider while enhancing the utilities of the vehicles. Furthermore, considering the resource limitation of the MEC server and the latency tolerance of the computation tasks, we propose a contract-based computation resource allocation scheme. Numerical results show that our proposed scheme greatly enhances the utility of the MEC service provider. ©2016 IEEE 

  • 3504.
    Zhang, Ke
    et al.
    School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu, China.
    Mao, Yuming
    School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu, China.
    Leng, Supeng
    School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu, China.
    Zeng, Ming
    School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu, China.
    Xu, Liang
    School of Communication and Information Engineering, University of Electronic Science and Technology of China, Chengdu, China.
    Jiang, Li
    Beijing University of Posts and Telecommunications, Beijing, China.
    Vinel, Alexey
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS), Centre for Research on Embedded Systems (CERES).
    Optimal energy exchange schemes in smart grid networks: A contract theoretic approach2016In: 2016 IEEE/CIC International Conference on Communications in China (ICCC), Piscataway, NJ: IEEE, 2016, article id 7636834Conference paper (Refereed)
    Abstract [en]

    Vehicle-to-Grid (V2G) is a promising paradigm to alleviate energy supply and demand imbalance of the grid. To further improve the power transmission efficiency, in this paper, we propose a cloudlet-based Vehicle-to-Vehicle (V2V) energy exchange framework. In the framework, the Energy Switch Center (ESC) serves as a trading broker, which purchases electricity from discharging vehicles and then resells it to the charging ones without energy transmission on the grid. The energy trading process is modeled in a contract theoretic approach. We derive the optimal feasible contracts which maximize the profit of the ESC. Furthermore, we systematically study the practical scenario where both the charging demand and renewable energy supplement are random variables, and propose a practical optimal contract-based electricity purchase scheme. Simulation results show that the proposed scheme can efficiently increase the profit of the ESC than the other mechanisms. © 2016 IEEE.

  • 3505.
    Zhang, Kewei
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Papadimitratos, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Analysis of the eect of the distance-decreasing aacks on GNSS authenticated signals2018In: WiSec 2018 - Proceedings of the 11th ACM Conference on Security and Privacy in Wireless and Mobile Networks, Association for Computing Machinery, Inc , 2018, p. 285-286Conference paper (Refereed)
    Abstract [en]

    Global Navigation Satellite Systems (GNSS) are vulnerable to jamming, spoong and replaying aacks because of their characteristics. Concerns regarding these aacks are being heightened because unmanned and autonomous vehicles become popular recently. Cryptographic methods have been proposed and are to be implemented in the Galileo and the GPS systems to counter spoong aacks. However, replaying aacks could still potentially harm GNSS receivers by bypassing the cryptographic methods. Distance-decreasing aacks is a strong type of replay aacks: it essentially resolves, from the aacker's point of view, the issue of introducing processing delay by implementing two phases: early detection and late commit. is poster analyzes the feasibility of distance-decreasing aacks against the GNSS navigation message authenticated signals and proposes countermeasures.

  • 3506. Zhang, L.
    et al.
    Wang, T.
    Liu, Q.
    Hu, X.
    Wang, Jing
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Su, Y.
    Increasing the delay-bit rate product on silicon chip using Star-16QAM signal with high spectral efficiency2009In: Optical Transmission Systems, Switching, and Subsystems VII, 2009, p. 763204-Conference paper (Refereed)
    Abstract [en]

    We proposed and experimentally demonstrate the generation of a novel star-16QAM using a dual-parallel Mach-Zehnder modulator (DPMZM) followed by a phase modulator (PM). Coherent detection and off-line processing are used to recover constellation diagrams. We also study optical delay of a novel star-16QAM signal through a silicon microring resonator. Delay time of ∼ 30ps is observed by comparing the eye diagram of the star-16QAM signal on-resonance with that off-resonance.

  • 3507. Zhang, L.
    et al.
    Wang, T.
    Liu, Q.
    Hu, X.
    Wang, Jing
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Su, Y.
    Increasing the delay-bit rate product on silicon chip using star-16QAM signal with high spectral efficiency2009In: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, 2009Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate optical delay of a novel star-16QAM signal through a silicon microring resonator. Delay time of ∼ 30ps is observed by comparing the eye diagram of the star-16QAM signal on-resonance with that off-resonance.

  • 3508. Zhang, Lei
    et al.
    Fu, Di
    Liu, Jiangchuan
    Ngai, Edith C.-H.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Zhu, Wenwu
    On energy-efficient offloading in mobile cloud for real-time video applications2017In: IEEE transactions on circuits and systems for video technology (Print), ISSN 1051-8215, E-ISSN 1558-2205, Vol. 27, no 1, p. 170-181Article in journal (Refereed)
  • 3509. Zhang, Lin
    et al.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Wu, Gang
    Zhao, Guodong
    Liang, Ying-Chang
    Li, Shaoqian
    Proactive Cross-Channel Gain Estimation for Spectrum Sharing in Cognitive Radio2016In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 34, no 10, p. 2776-2790Article in journal (Refereed)
    Abstract [en]

    In an underlay cognitive radio network, the cross-channel gain from a cognitive transmitter (CT) to a primary receiver (PR) is crucial for spectrum sharing. By exploiting the relaying capability of the CT, we propose a proactive estimation scheme for the cross-channel gain. Specifically, the CT proactively acts as a full-duplex amplify-and-forward (AF) relay for primary transceivers to trigger the power adaption of a primary transmitter (PT). By carefully designing the relay signal, the CT is able to obtain an estimation of the cross-channel gain by observing the power adaption. To demonstrate the accuracy of the estimation, we analytically characterize both an upper bound and a lower bound of the estimation performance. Furthermore, we study the impact of CT's relaying on the primary transmission and observe that the impact is related to the CT's location. By introducing a factor phi (0 <= phi <= 1) to denote the probability that the CT's relaying improves the primary transmission instead of causes interference, we design the CT location as a function of f. Numerical results show that the estimation error of the proactive estimation scheme can be as small as 1.7% with success estimation probability around 91%. By comparing with the state of the art, we show the advantages of the proposed estimator.

  • 3510.
    Zhang, Lu
    et al.
    KTH. Shanghai Jiao Tong University, China.
    Pang, Xiaodan
    KTH. RISE Acreo AB, Sweden.
    Ozolins, O.
    Udalcovs, A.
    Popov, Sergei
    KTH.
    Xiao, S.
    Chen, Jiajia
    KTH.
    K-means clustering based multi-dimensional quantization scheme for digital mobile fronthaul2018In: Optics InfoBase Conference Papers, Optics Info Base, Optical Society of America, 2018Conference paper (Refereed)
    Abstract [en]

    We propose to group highly-correlated neighboring samples into multi-dimensional vectors and adopt k-means clustering for quantization in mobile fronthaul. 30-Gbit/s transmissions have been experimentally demonstrated for up to 40 100MHz LTE channels over 20km fiber.

  • 3511.
    Zhang, Lu
    et al.
    KTH, School of Information and Communication Technology (ICT). Shanghai Jiao Tong University, Shanghai, China.
    Pang, Xiaodan
    KTH, School of Information and Communication Technology (ICT). RISE Acreo AB, Kista, Sweden.
    Ozolins, O.
    Udalcovs, A.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT).
    Westergren, Urban
    KTH, School of Information and Communication Technology (ICT).
    Jacobsen, G.
    Popov, Sergei
    KTH, School of Information and Communication Technology (ICT).
    Xiao, S.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT).
    15-Gbaud PAM4 Digital Mobile Fronthaul with Enhanced Differential Pulse Coding Modulation Supporting 122 LTE-A Channels with up to 4096QAM2018In: 2017 European Conference on Optical Communication (ECOC), Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 1-3Conference paper (Refereed)
    Abstract [en]

    By employing enhanced DPCM, 15-Gbaud PAM4 digital mobile fronthaul is experimentally demonstrated to support 122 LTE-A channels with up to 4096QAM. Compared to PCM based CPRI, the supported number of channels increases 5 times and EVM is obviously improved.

  • 3512.
    Zhang, Lu
    et al.
    KTH. Shanghai Jiao Tong Univ, State Key Lab Adv Opt Commun Syst & Networks, Shanghai, Peoples R China..
    Pang, Xiaodan
    KTH. KTH Royal Inst Technol, Stockholm, Sweden.;RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Ozolins, Oskars
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Udalcovs, Aleksejs
    RISE Acreo AB, Networking & Transmiss Lab, Kista, Sweden..
    Popov, Sergei
    KTH.
    Xiao, Shilin
    Shanghai Jiao Tong Univ, State Key Lab Adv Opt Commun Syst & Networks, Shanghai, Peoples R China..
    Chen, Jiajia
    KTH.
    K-means Clustering based Multi-Dimensional Quantization Scheme for Digital Mobile Fronthaul2018In: 2018 Optical Fiber Communications Conference and Exposition, OFC 2018 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2018Conference paper (Refereed)
    Abstract [en]

    We propose to group highly-correlated neighboring samples into multi-dimensional vectors and adopt k-means clustering for quantization in mobile fronthaul. 30-Gbit/s transmissions have been experimentally demonstrated for up to 40 100MHz LTE channels over 20km fiber.

  • 3513.
    Zhang, Lu
    et al.
    KTH. Shanghai Jiao Tong University, Shanghai, China.
    Pang, Xiaodan
    KTH. RISE Acreo AB, Networking & Transmiss Lab, S-16425 Kista, Sweden.
    Ozolins, Oskars
    Udalcovs, Aleksejs
    Popov, Sergei
    Xiao, Shilin
    Hu, Weisheng
    Chen, Jiajia
    KTH. South China Normal Univ, South China Acad Adv Optoelect, MOE Int Lab Opt Informat Technol, Guangzhou 510006, Guangdong, Peoples R China.
    Spectrally efficient digitized radio-over-fiber system with k-means clustering-based multidimensional quantization.2018In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 43, no 7, p. 1546-1549Article in journal (Refereed)
    Abstract [en]

    We propose a spectrally efficient digitized radio-over-fiber (D-RoF) system by grouping highly correlated neighboring samples of the analog signals into multidimensional vectors, where the k-means clustering algorithm is adopted for adaptive quantization. A 30  Gbit/s D-RoF system is experimentally demonstrated to validate the proposed scheme, reporting a carrier aggregation of up to 40 100 MHz orthogonal frequency division multiplexing (OFDM) channels with quadrate amplitude modulation (QAM) order of 4 and an aggregation of 10 100 MHz OFDM channels with a QAM order of 16384. The equivalent common public radio interface rates from 37 to 150  Gbit/s are supported. Besides, the error vector magnitude (EVM) of 8% is achieved with the number of quantization bits of 4, and the EVM can be further reduced to 1% by increasing the number of quantization bits to 7. Compared with conventional pulse coding modulation-based D-RoF systems, the proposed D-RoF system improves the signal-to-noise-ratio up to ∼9  dB and greatly reduces the EVM, given the same number of quantization bits.

  • 3514.
    Zhang, P.
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Costa, J.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Tekeusso, Boris
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Wahlstrand, N.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Carmona, O.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    M2M Communications in LTE SystemsIn: Wireless networks, ISSN 1022-0038, E-ISSN 1572-8196Article in journal (Other academic)
    Abstract [en]

    In wide-area applications, low-cost and massive machine to machine (M2M) communications provided bycellular networks will be one main driver for the success of future Internet of Things (IoT) development. The first directconsequence of the proliferation of IoT is that large numbers of devices will produce huge quantities of sporadic data andsignificantly higher capacity of cellular networks will be needed - not in terms of megabits transported, but the numberof machines sustained. In this paper, we will investigate the support of M2M communications in LTE systems. The goalof this paper is to survey how the existing LTE architecture supports M2M traffic in terms of capacity, coverage, andsignaling, assuming a certain usage scenario and traffic pattern. Solutions are suggested for issues that arise whena large amount of M2M traffic is transported over an LTE network. We will show that the capacity and coverage arenot the key issues; instead the signaling is the main bottleneck, especially the ones related to the RACH. Finally, as atypical illustrating example, we will study in detail how Smart Metering application can be supported in LTE systems andinvestigate thoroughly solutions to the key bottlenecks in this paper.

  • 3515. Zhang, Peilin
    et al.
    Gao, Alex Yuan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Theel, Oliver
    Less is More: Learning more with concurrent transmissions for energy-efficient flooding2017In: Proc. 14th International Conference on Mobile and Ubiquitous Systems: Computing, Networking and Services, New York: ACM Press, 2017Conference paper (Refereed)
  • 3516. Zhang, Peilin
    et al.
    Gao, Yuan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Theel, Oliver E.
    Bandit Learning with Concurrent Transmissions for Energy-Efficient Flooding in Sensor Networks2018Conference paper (Refereed)
    Abstract [en]

    Concurrent transmissions, a novel communication paradigm, has been shown to effectively accomplish a reliable and energy-efficient flooding in low-power wireless networks. With multiple nodes exploiting a receive-and-forward scheme in the network, this technique inevitably introduces communication redundancy and consequently raises the energy consumption of the nodes. In this article, we propose Less is More (LiM), an energy-efficient flooding protocol for wireless sensor networks. LiM builds on concurrent transmissions, exploiting constructive interference and the capture effect to achieve high reliability and low latency. Moreover, LiM is equipped with a machine learning capability to progressively reduce redundancy while maintaining high reliability. As a result, LiM is able to significantly reduce the radio-on time and therefore the energy consumption. We compare LiM with our baseline protocol Glossy by extensive experiments in the 30-node testbed FlockLab. Experimental results show that LiM highly reduces the broadcast redundancy in flooding. It outperforms the baseline protocol in terms of radio-on time, while attaining a high reliability of over 99.50% and an average end-to-end latency around 2 milliseconds in all experimental scenarios.

  • 3517.
    Zhang, Peng
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Energy-Efficient Clustering Design for M2M Communications2014In: 2014 IEEE Global Conference on Signal and Information Processing (GlobalSIP), 2014Conference paper (Refereed)
    Abstract [en]

    Machine-to-machine (M2M) communications in cellular networks enables Internet of Things in the macro geographical regions and is a promising technique in next-generation wireless networks. In this paper, we study energy-efficient clusteringdesign in cellular networks to maximize the overall network battery life time.

    We propose a new clustering design which finds the optimal number of clusters in a cellular network, and maximizes the network energy efficiency, meanwhile rulesof selecting and rotating cluster heads. Different from existing clustering designs, we consider both transmission and circuit energy consumption in this paper. The network performance will be both rigorously analyzed and evaluated using simulations withrespect to dead device ratio, residual energy, and network life. The simulation results show that by using the proposed clustering approach, the network battery life can be improved significantly.

  • 3518.
    Zhang, Shasha
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Device aggregation with data networking: Implementing a Personal Area Network2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Technology is advancing rapidly and intelligent devices are becoming affordable and wireless infrastructure is becoming pervasive. Personal information technology appliances have become part of our life, via cellular phones, PDAs, Bluetooth headsets, handheld keyboards, GPS, and digital cameras. In the future, new intelligent devices will be invented as technology evolves. However, because multiple devices provide similar (but different) functionality it is complex for the average user to choose a single device. Moreover, today it is hard to configure, administer, and use several different appliances together. In order to be utilized in an effective manner and in an accessible way, personal devices should be aggregated, i.e., connected together via a local area network so that they can appear to the user as if they were a single device.

    This paper introduces a connection model based on device aggregation to realize shared state, the behavior of a shared appliance, and with the superset of the individual device functionality. Such an aggregated logical device might even exhibit functions which a user would have a very hard time realizing by manually combining devices. This will facilitate the user’s control over their appliances (build of different devices), but acting as one device.

    The project was a joint effort with David Sabaté Mogica. We developed such a system based on Dynamic Host Client protocol (DHCP) and Service Location Protocol (SLP) for service discovery and Virtual Network Computing (VNC) for remote desktop control. The system builds on a laboratory network environment. This thesis concerns the implementation and evaluation of service discovery. The Remote desktop control was researched and implemented separately and will be reported separately. Service discovery between two computers has been implemented using a custom program developed for a PDA. However, at present the PDA only sends a DA request packet with DHCP. However, service discovery has been successfully tested between two computers. This provided an important base for the programming on PDA and the future development of a similar program for a cellular phone.

  • 3519.
    Zhang, Xi
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Palomar, Daniel P.
    Dept. of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Robust design of linear MIMO transceivers under channel uncertainty2006In: 2006 IEEE International Conference on Acoustics, Speech, and Signal Processing: signal processing for communication, sensor array and multichannel signal processing, 2006, p. 77-80Conference paper (Refereed)
    Abstract [en]

    This paper considers the robust design of a linear transceiver with imperfect channel state information (CSI) at the transmitter of a MIMO link. The framework embraces the design problem when CSI at the transmitter consists of the channel mean and covariance matrix or, equivalently, the channel estimate and the estimation error covariance matrix. The design of the linear MIMO transceiver is based on a general cost function covering several well known performance criteria. In particular, two families are considered in detail: Schur-convex and Schur-concave functions. Approximations are used in the low SNR and high SNR regimes separately to obtain simple optimization problems that can be readily solved. Numerical examples show gains compared to other suboptimal methods.

  • 3520.
    Zhang, Xi
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Palomar, Daniel P.
    Electrical Engineering, Princeton University, Princeton.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Statistically robust design of linear MIMO transceivers2008In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 56, no 8, p. 3678-3689Article in journal (Refereed)
    Abstract [en]

    The treatment of channel state information (CSI) is critical in the design of MIMO systems. Accurate CSI at the transmitter is often not possible or may require high feedback rates. Herein, we consider the robust design of linear MIMO transceivers with perfect CSI either at the transmitter or at both sides of the link. The framework considers the design problem where the imperfect CSI consists of the channel mean and covariance matrix or, equivalently, the channel estimate and the estimation error covariance matrix. The robust transceiver design is based on a general cost function of the average MSEs as well as a design with individual MSE based constraints. In particular, a lower bound of the average MSE matrix is explored for the design when only the CSI at the transmitter is imperfect. Under different CSI conditions, the proposed robust transceivers exhibit a similar structure to the transceiver designs for perfect CSI, but with a different equivalent channel and/or noise covariance matrix.

  • 3521. Zhang, Xu
    et al.
    Othman, Maisara B
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Jensen, Jesper B
    Monroy, Idelfonso Tafur
    Bi-directional multi dimension CAP transmission for smart grid communication services2012In: Communications and Photonics Conference (ACP), 2012 Asia, Optical Society of America, 2012, p. 1-3Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate bi-directional multi dimension carrierless amplitude and phase (CAP) transmission for smart grid communication services based on optical fiber networks. The proposed system is able to support multi-Gb/s transmission with high spectral efficiency.

  • 3522. Zhang, Xu
    et al.
    Pang, Xiaodan
    Technical University of Denmark, Denmark.
    Deng, Lei
    Zibar, Darko
    Monroy, Idelfonso Tafur
    Younce, Richard
    High phase noise tolerant pilot-tone-aided DP-QPSK optical communication systems2012In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, no 18, p. 19990-19995Article in journal (Refereed)
    Abstract [en]

    In this paper we experimentally demonstrate a novel, high phase-noise tolerant, optical dual polarization (DP) quadrature phase-shift keying (QPSK) communication system based on pilot-tone-aided phase noise cancellation (PNC) algorithm. Vertical cavity surface emitting lasers (VCSELs) with approximate 300 MHz linewidth are used as transmitters and local oscillators for coherent detection of optical DP-QPSK signals. The proposed system, with central wavelength at 1540.68 nm, operates at 40 Gb/s over 80 km single mode fiber (SMF) as part of a passive optical network (PON). The deployment of pilot-tone-aided PNC algorithm guarantees a bit error rate (BER) performance below the forward error correction (FEC) threshold. Moreover, we also evaluate a novel digital signal processing (DSP) algorithm for adaptive pilot tone detection.

  • 3523. Zhang, Xu
    et al.
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Dogadaev, Anton K
    Monroy, Idelfonso Tafur
    Zibar, Darko
    Younce, Richard C
    High spectrum narrowing tolerant 112 Gb/s dual polarization QPSK optical communication systems using digital adaptive channel estimation2012In: 2012 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2012, 2012Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate high spectrum narrowing tolerant 112-Gb/s QPSK polarization multiplex system based on digital adaptive channel estimation method. The proposed algorithm is able to detect severe spectrum-narrowed signal even with 20GHz 3dB bandwidth.

  • 3524.
    Zhang, Yan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Wireless sensor network for volcano monitoring2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The monitoring of volcanoes for risk assessment has deployed single sensors for years. This kind of system requires manual supervision to monitor each sensor, which makes the monitoring work not flexible and efficient enough to adapt to variable volcano environments. With the development of wireless sensor networks, the accuracy and coverage of volcano observations can be improved by deploying networked sensors. This paper proposes a wireless sensor network prototype for volcano remote monitoring, which was built and tested in a field campaign in volcano Etna, Italy in September of 2004.Hardware design of sensors, in-depth sensor network design and software module architecture will be introduced in this paper. The experience gained from the practical work in volcano Etna will be used in an upcoming volcano monitoring project.

  • 3525.
    Zhang, Yuanhui
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Evaluating a publish/subscribe proxy for HTTP2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the increasingly high speed of the Internet and its wide spread usage, the current Internet architecture exhibits some problems. The publish/subscribe paradigm has been developed to support one of the most common patterns of communication. It makes “information” the center of communication and removes the “location-identity split” (i.e., that objects are at specific locations to which you must communicate with to access the object). In this thesis project a publish/subscribe network is built and then used in the design, implementation, and evaluation of a publish/subscribe proxy for today’s HTTP based communication. By using this proxy users are able to use their existing web browser to send both HTTP requests and Publish/Subscribe Internet Routing Paradigm (PSIRP) requests. A publish/subscribe overlay is responsible for maintaining PSIRP contents. The proxy enables web browser clients to benefit from the publish/subscribe network, without requiring them to change their behavior or even be aware of the fact that the content that they want to access is being provided via the publish/subscribe overlay. The use of the overlay enables a user’s request to be satisfied by any copy of the content, potentially decreasing latency, reducing backbone network traffic, and reducing the load on the original content server. One of the aims of this thesis is to make more PSIRP content available, this is done by introducing a proxy who handles both HTTP and PSIRP requests, but having received content as a result of an HTTP response it publishes this data as PSIRP accessible content. The purpose is to foster the introduction and spread of content based access.

  • 3526. Zhang, Zhengquan
    et al.
    Ma, Zheng
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Information Science and Engineering. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Ding, Zhiguo
    Fan, Pingzhi
    Full-Duplex Device-to-Device-Aided Cooperative Nonorthogonal Multiple Access2017In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 66, no 5, p. 4467-4471Article in journal (Refereed)
    Abstract [en]

    This paper presents a full-duplex device-to-device (D2D)-aided cooperative nonorthogonal multiple access (NOMA) scheme to improve the outage performance of the NOMA-weak user in a NOMA user pair, where the NOMA-weak user is helped by the NOMA-strong user with the capability of full-duplex D2D communications. The expressions for the outage probability are derived to characterize the performance of the proposed scheme. The results show that the proposed cooperative NOMA scheme can achieve superior outage performance compared to the conventional NOMA and orthogonal multiple access (OMA). In order to further improve the outage performance, an adaptive multiple access (AMA) scheme is also studied, which dynamically switches between the proposed cooperative NOMA, conventional NOMA, and OMA schemes, according to the level of residual self-interference and the quality of links. The results show that the AMAscheme outperforms the above multiple access schemes in terms of outage performance.

  • 3527.
    Zhang, Zhengquan
    et al.
    Southwest Jiaotong Univ, Chengdu, Sichuan, Peoples R China..
    Yang, Guang
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Ma, Zheng
    Southwest Jiaotong Univ, Chengdu, Sichuan, Peoples R China.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Ding, Zhiguo
    Univ Lancaster, Lancaster, Lancs, England..
    Fan, Pingzhi
    Southwest Jiaotong Univ, Inst mobile Commun, Chengdu, Sichuan, Peoples R China..
    Heterogeneous Ultradense Networks with NOMA System Architecture, Coordination Framework, and Performance Evaluation2018In: IEEE Vehicular Technology Magazine, ISSN 1556-6072, E-ISSN 1556-6080, Vol. 13, no 2, p. 110-120Article in journal (Refereed)
    Abstract [en]

    Heterogeneous ultradense networks (H-UDNs) are one key enabler for fifth-generation (5G) wireless networks and beyond to satisfy the explosive growth of mobile data traffic, which exploits spatial reuse of scarce spectrum by deploying massive base stations (BSS) to boost network capacity and enhance network coverage. In this article, we present the system architecture for 5G H-UDNs, consisting of virtualized integrated ground-Air-space radio access networks (RANs) and core networks and study network coordination for virtualized H-UDN to efficiently manage computing resources and intercell interference. We look at a cloud-fog-computing coordination framework for efficient computing resource management by achieving reasonable computing task distribution and transfer; computing load balance for computing tasks among virtual computing resources to improve network performance and computing resource efficiency; and a macro-small cell coordination framework for virtualized H-UDN with nonorthogonal multiple access (NOMA) to efficiently manage intercell interference and improve network performance. The joint macro-small enhanced intercell interference coordination (eICIC) and small-small coordinated multipoint joint transmission (CoMP-JT) scheme can efficiently eliminate macro-small intercell interference and utilize small-small intercell interference.

  • 3528.
    Zhang, Zhi
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Lu, Zhonghai
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Chen, Qiang
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Yan, Xiaolang
    Zheng, Li-Rong
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Code division multiple access/pulse position modulation ultra-wideband radio frequency identification for Internet of Things: concept and analysis2012In: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 25, no 9, p. 1103-1121Article in journal (Refereed)
    Abstract [en]

    Radio frequency identification (RFID) is a compelling technology for Internet of Things (IoT). Ultra-wideband (UWB) technology is one promising wireless technique for future RFID, especially for high-throughput sensing applications. On-off keying UWB RFID system provides high pulse rate but suffers severe collisions that limit the system throughput. This paper proposes to utilize low pulse rate code division multiple access/pulse position modulation UWB in the tag-to-reader link to provide multiple tag access capability and build a high-throughput RFID system for IoT. We analyze asynchronous matched filter receiver and decorrelating receiver for multi-tag detection and design an effective medium access control scheme to optimize the network throughput. We propose an effective dynamic frame size adjustment algorithm on the basis of theoretical analysis and determine the preferable length of Gold codes. With a similar data rate, the throughput of the proposed system using the decorrelating receiver is 8.6 times higher than that of the electronic product code class 1 generation 2 system. Only using 1/10 pulse rate and 1/15 data rate, the proposed system outperforms the on-off keying UWB RFID system 1.4 times in terms of throughput.

  • 3529.
    Zhao, Hao
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Secure Management of Multi-Application Mobile Platforms2014Doctoral thesis, monograph (Other academic)
  • 3530.
    Zhao, Hao
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Muftic, Sead
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    The concept of secure mobile wallet2011In: World Congress on Internet Security, WorldCIS-2011, 2011, p. 54-58Conference paper (Refereed)
    Abstract [en]

    This paper describes our concept, design and current implementation of the Secure Mobile Wallet. Mobile Wallet is an application stored in mobile phones providing to subscribers the possibility to perform various mobile financial transactions. In our approach Secure Mobile Wallet is stored and running in the Javacard SIM chip, called UICC. It comprises several Javacard applets supporting several types of financial transactions - mobile banking, mobile payments, mobile commerce, mobile micro-loans, mobile ticketing, mobile promotions, and so on. Secure Mobile Wallet supports over-the-air (OTA) transactions based on SMS, GPRS, or mobile Internet protocols and also over-the-counter (OTC) transactions based on NFC or Bluetooth protocols. For users, messages and data stored in the Secure Mobile Wallet are managed and maintained using both, OTA and OTC, protocols. Security is guaranteed by a combination of symmetric and asymmetric cryptography. As a client's application, the Secure Mobile Wallet is integrated into our larger, secure mobile transactions system - SAFE™.

  • 3531.
    Zhao, Hao
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Communication Systems, CoS (closed 2012-01-01).
    Muftic, Sead
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Communication Systems, CoS (closed 2012-01-01).
    Zhang, Feng
    KTH, School of Information and Communication Technology (ICT), Communication: Services and Infrastucture (Closed 20120101), Communication Systems, CoS (closed 2012-01-01).
    The secure mobile wallet: Anytime, anywhere financial transactions2010In: Cutter IT Journal, ISSN 1522-7383, Vol. 23, no 7, p. 32-35Article in journal (Refereed)
  • 3532.
    Zhao, Peiyue
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering. KTH Royal Inst Technol, S-11428 Stockholm, Sweden..
    Fodor, Gabor
    Ericsson Res, S-16480 Stockholm, Sweden..
    Dan, Gyorgy
    Budapest University of Technology and Economics, Budapest, Hungary.
    Telek, Miklos
    MTA BME Informat Syst Res Grp, H-1117 Budapest, Hungary.
    A Game Theoretic Approach to Setting the Pilot Power Ratio in Multi-User MIMO Systems2018In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 66, no 3, p. 999-1012Article in journal (Refereed)
    Abstract [en]

    We consider the uplink of a single cell multi-user multiple input multiple output (MU-MIMO) system, in which the base station acquires channel state information at the receiver by means of uplink pilot signals. Since each mobile station has a sum power budget that is used to transmit pilot and data symbols, the pilot power ratio (PPR) has a large impact on the system performance in terms of spectral and energy efficiency. We formulate the problem of PPR setting as a non-cooperative game, in which each mobile station aims at minimizing the mean squared error of the uplink received data symbols at the base station. We show that in this game a unique Nash equilibrium exists, and propose an iterative decentralized algorithm-termed best PPR algorithm (BPA)-that is guaranteed to converge to that Nash equilibrium. Since BPA dynamically responds to the measured interference, it outperforms widely used schemes that use a predetermined PPR. BPA also performs close to the global optimum, especially when mobile stations with similar path loss values are co-scheduled in the MU-MIMO system. Based on these insights, we propose a practical signaling mechanism for implementing BPA in MU-MIMO systems.

  • 3533.
    Zhao, Wang
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Hu, JianHao
    Xiong, Xing Zhong
    Song, Jie
    Non-data-aided timing acquisition for asynchronous IDMA systems2012In: Wireless personal communications, ISSN 0929-6212, E-ISSN 1572-834X, Vol. AprilArticle in journal (Refereed)
    Abstract [en]

    Sample-timing error can cause significant performance degradation for the interleave-

    division multiple-access systems (Wang et al.2009). In this paper, we propose a nondata-aided timing acquisition scheme tomitigate sample-timing error due to the asynchronoustransmission of random allocated user ends (UEs) on the uplink.Aclosed-loop timing control scheme is constructed for the asynchronous IDMA system in this paper.We use the extrinsic information generated during the iterative detection algorithm with signal noise ratio  volution to estimate the timing offset for the asynchronous uplink in the base station (BS) receiver. The BS receiver returns the timing control bits, which is generated with estimated timing offsets, to the corresponding UE. And the UE uses the timing control bits to adjust local transmission time to guarantee the sampling performance at the BS receiver. The simulation results show that the proposed acquisition scheme based on feedback loop can provide high acquisition probability and low false alarm probability. The proposed scheme can overcome the bit-error-rate performance bottleneck, which is caused by the sample-timing error in BS receiver due to the asynchronous signals in the uplink.

  • 3534.
    Zhao, Wei
    et al.
    Ericsson Research.
    Andersson, Loa
    Ericsson AB.
    Sköldström, Pontus
    Acreo AB.
    Prototyping MPLS-TP forwarding and OAM2009In: 5th International Conference on IP + Optical Network, 2009Conference paper (Refereed)
  • 3535.
    Zhao, Xueqian
    KTH, School of Information and Communication Technology (ICT), Electronics and Embedded Systems.
    Network on Chip: Performance Bound and Tightness2015Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Featured with good scalability, modularity and large bandwidth, Network-on-Chip (NoC) has been widely applied in manycore Chip Multiprocessor (CMP) and Multiprocessor System-on-Chip (MPSoC) architectures. The provision of guaranteed service emerges as an important NoC design problem due to the application requirements in Quality-of-Service (QoS).

    Formal analysis of performance bounds plays a critical role in ensuring guaranteed service of NoC by giving insights into how the design parameters impact the network performance. The study in this thesis proposes analysis methods for delay and backlog bounds with Network Calculus (NC). Based on xMAS (eXecutable Micro-Architectural Specification), a formal framework to model communication fabrics, the delay bound analysis procedure is presented using NC. The micro-architectural xMAS representation of a canonical on-chip router is proposed with both the data flow and control flow well captured. Furthermore, a well-defined xMAS model for a specific application on an NoC can be created with network and flow knowledge and then be mapped to corresponding NC analysis model for end-to-end delay bound calculation. The xMAS model effectively bridges the gap between the informal NoC micro-architecture and the formal analysis model. Besides delay bound, the analysis of backlog bound is also crucial for predicting buffer dimensioning boundary in on-chip Virtual Channel (VC) routers. In this thesis, basic buffer use cases are identified with corresponding analysis models proposed so as to decompose the complex flow contention in a network. Then we develop a topology independent analysis technique to convey the backlog bound analysis step by step. Algorithms are developed to automate this analysis procedure.

    Accompanying the analysis of performance bounds, tightness evaluation is an essential step to ensure the validity of the analysis models. However, this evaluation process is often a tedious, time-consuming, and manual simulation process in which many simulation parameters may have to be configured before the simulations run. In this thesis, we develop a heuristics aided tightness evaluation method for the analytical delay and backlog bounds. The tightness evaluation is abstracted as constrained optimization problems with the objectives formulated as implicit functions with respect to the system parameters. Based on the well-defined problems, heuristics can be applied to guide a fully automated configuration searching process which incorporates cycle-accurate bit-accurate simulations. As an example of heuristics, Adaptive Simulated Annealing (ASA) is adopted to guide the search in the configuration space. Experiment results indicate that the performance analysis models based on NC give tight results which are effectively found by the heuristics aided evaluation process even the model has a multidimensional discrete search space and complex constraints.

    In order to facilitate xMAS modeling and corresponding validation of the performance analysis models, the thesis presents an xMAS tool developed in Simulink. It provides a friendly graphical interface for xMAS modeling and parameter configuring based on the powerful Simulink modeling environment. Hierarchical model build-up and Verilog-HDL code generation are essentially supported to manage complex models and conduct simulations. Attributed to the synthesizable xMAS library and the good extendibility, this xMAS tool has promising use in application specific NoC design based on the xMAS components.

  • 3536. Zhao, Ying
    et al.
    Deng, Lei
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Yu, Xianbin
    Zheng, Xiaoping
    Zhang, Hanyi
    Monroy, Idelfonso Tafur
    Digital predistortion of 75–110 GHz W-band frequency multiplier for fiber wireless short range access systems2011In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 19, no 26, p. 18-25Article in journal (Refereed)
    Abstract [en]

    We present a W-band fiber-wireless transmission system based on a nonlinear frequency multiplier for high-speed wireless short range access applications. By implementing a baseband digital signal predistortion scheme, intensive nonlinear distortions induced in a sextuple frequency multiplier can be effectively pre-compensated. Without using costly W-band components, a transmission system with 26km fiber and 4m wireless transmission operating at 99.6GHz is experimentally validated. Adjacent-channel power ratio (ACPR) improvements for IQ-modulated vector signals are guaranteed and transmission performances for fiber and wireless channels are studied. This W-band predistortion technique is a promising candidate for applications in high capacity wireless-fiber access systems.

  • 3537. Zhao, Ying
    et al.
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Deng, Lei
    Othman, Maisara B
    Yu, Xianbin
    Zheng, Xiaoping
    Zhang, Hanyi
    Monroy, Idelfonso T
    Experimental demonstration of 5-Gb/s polarization-multiplexed fiber-wireless MIMO systems2011In: 2011 IEEE International Topical Meeting on Microwave Photonics - Jointly Held with the 2011 Asia-Pacific Microwave Photonics Conference, MWP/APMP 2011, 2011, p. 13-16, article id 6088657Conference paper (Refereed)
    Abstract [en]

    We experimentally demonstrate a 5-Gb/s fiber-wireless transmission system combining optical polarization-division-multiplexing (PDM) and wireless multiple-input, multiple-output (MIMO) spatial multiplexing technologies. The optical-wireless channel throughput is enhanced by achieving a 4b/s/Hz spectral efficiency. Based on the implementation of constant modulus algorithm (CMA), the 2x2 MIMO wireless channel is characterized and adaptively equalized for signal demodulation. The performance of the CMA-based channel adaptation is studied and it is revealed that the algorithm is particularly advantageous to the MIMO wireless system due to the inter-channel delay insensitivity. The hybrid transmission performance of 26km fiber and up to 2m wireless MIMO is investigated.

  • 3538. Zhao, Ying
    et al.
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Deng, Lei
    Yu, Xianbin
    Zheng, Xiaoping
    Monroy, Idelfonso Tafur
    Ultra-Broadband Photonic Harmonic Mixer Based on Optical Comb Generation2012In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 24, no 1, p. 16-18, article id 6045319Article in journal (Refereed)
    Abstract [en]

    We propose a novel photonic harmonic mixer operating at frequencies up to the millimeter-wave (MMW) band. By combining a broadband fiber-wireless signal with high-order harmonics of a fundamental local oscillator in an optical frequency comb generator, frequency down-conversion can be implemented without using a costly ultra-broadband photodiode. It is theoretically shown that the down-conversion efficiency and the bandwidth of the mixer is highly dependent on the optical modulation indices and the fundamental frequency of comb lines. Down-conversion of a W-band (75-110 GHz) fiber-wireless signal is experimentally demonstrated. Moreover, the error vector magnitude (EVM) performance of a multigigabit quadrature phase-shift-keying (QPSK) signal at 62.5-, 82.5-, and 102.5-GHz carrier frequencies is studied to evaluate the down-conversion efficiency. The proposed photonic harmonic mixer can be a candidate for applications in high capacity fiber-wireless communication systems.

  • 3539. Zhao, Ying
    et al.
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Deng, Lei
    Yu, Xianbin
    Zheng, Xiaoping
    Zhou, Bingkun
    Monroy, Idelfonso Tafur
    High accuracy microwave frequency measurement based on single-drive dual-parallel Mach-Zehnder modulator2011In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 19, no 26, p. 681-686Article in journal (Refereed)
    Abstract [en]

    A novel approach for broadband microwave frequency measurement by employing a single-drive dual-parallel Mach-Zehnder modulator is proposed and experimentally demonstrated. Based on bias manipulations of the modulator, conventional frequency-to-power mapping technique is developed by performing a two-stage frequency measurement cooperating with digital signal processing. In the experiment, 10GHz measurement range is guaranteed and the average uncertainty of estimated microwave frequency is 5.4MHz, which verifies the measurement accuracy is significantly improved by achieving an unprecedented 10(-3) relative error. This high accuracy frequency measurement technique is a promising candidate for high-speed electronic warfare and defense applications.

  • 3540.
    Zhao, Yuxin
    et al.
    Ericsson Research, Linköping, Sweden.
    Yin, Feng
    Ericsson Research, Linköping, Sweden.
    Gunnarsson, Fredrik
    Ericsson Research, Linköping, Sweden.
    Amirijoo, Mehdi
    Ericsson Research, Linköping, Sweden.
    Hendeby, Gustaf
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Gaussian Process for Propagation modeling and Proximity Reports Based Indoor Positioning2016In: 2016 IEEE 83rd Vehicular Technology Conference (VTC Spring), IEEE , 2016, p. 1-5Conference paper (Refereed)
    Abstract [en]

    The commercial interest in proximity services is increasing. Application examples include location-based information and advertisements, logistics, social networking, file sharing, etc. In this paper, we consider network-based positioning based on times series of proximity reports from a mobile device, either only a proximity indicator, or a vector of RSS from observed nodes. Such positioning corresponds to a latent and nonlinear observation model. To address these problems, we combine two powerful tools, namely particle filtering and Gaussian process regression (GPR) for radio signal propagation modeling. The latter also provides some insights into the spatial correlation of the radio propagation in the considered area. Radio propagation modeling and positioning performance are evaluated in a typical office area with Bluetooth-Low-Energy (BLE) beacons deployed for proximity detection and reports. Results show that the positioning accuracy can be improved by using GPR.

  • 3541.
    Zhao, Yuxin
    et al.
    Ericsson Research, Linköping, Sweden.
    Yin, Feng
    Ericsson Research, Linköping, Sweden.
    Gunnarsson, Fredrik
    Ericsson Research, Linköping, Sweden.
    Amirijoo, Mehdi
    Ericsson Research, Linköping, Sweden.
    Özkan, Emre
    ISY, Linköping University.
    Gustafsson, Fredrik
    ISY, Linköping University.
    Particle Filtering for Positioning Based on Proximity Reports2015Conference paper (Refereed)
    Abstract [en]

    The commercial interest in proximity services is increasing. Application examples include location-based information and advertisements, logistics, social networking, file sharing, etc. In this paper, we consider positioning of devices based on time series proximity reports from a mobile device to a network node. This corresponds to nonlinear measurements with respect to the device position in relation to the network nodes. Therefore, particle filtering is applicable for positioning. Positioning performance is evaluated in a typical office area with Bluetooth-low-energy beacons deployed for proximity detection and report. Accuracy is concluded to vary spatially over the office floor, and in relation to the beacon deployment density.

  • 3542.
    Zhao, Zhengjian
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Mediating updates using a web based service2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The European Commission had approved the Registration, Evaluation and Authorization of Chemicals (REACH) regulations in the year 2006, and will begin to implement it form 1 June 2007. This regulation greatly increases safety of protection for the users of chemicals, but it also brought a problem for the manufactures as well as downstream users. That is they have to generate and distribute much more Material Safety Data Sheets (MSDS) then before. This work is difficult for most companies since this job usually was done manually. The new regulation requires a much more efficient method to generate and distribute them.

    This thesis project addresses the problem of automatically distributing MSDS and the corresponding metadata. It presents the underlying technology selected for this project. It gives a brief introduction of this project, the underlying technologies used, along with the methods used to deliver relevant and up to date materials safety information.

    At last an HTTP web application approach was selected to solve the problem, the resulting application can efficiently notify a downstream user of the newly updated MSDS and transport the corresponding file and metadata. It is truly data driven, therefore the downstream user does not need to check for updates everyday, instead will be notified when there is an available update.

  • 3543. Zheng, G.
    et al.
    Li, J.
    Wong, K. -K
    Petropulu, A. P.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Using simple relays to improve physical-layer security2012In: Communications in China (ICCC), 2012 1st IEEE International Conference on, IEEE , 2012, p. 329-333Conference paper (Refereed)
    Abstract [en]

    This paper studies different uses of two cooperating relays to improve the secrecy rate of a wiretap channel. These two relays are assumed to perform only simple functions: either amplify-and-forward (AF) or jamming. Complex functions such as decode-and-forward (DF) are not considered. We study three modes of cooperation: i) cooperative jamming (CJ), ii) AF-aided beamforming and iii) mixed AF-aided beamforming and CJ, all with individual relay power constraints. While i) is known in the literature, our efforts are spent on ii) and iii). In particular, for iii), we assume that the jamming signals in two communication stages are correlated, giving rise to improved performances. We also propose a heuristic approach for selecting the appropriate cooperating mode. Simulation results illustrate the performance gain of each scheme under different channel conditions and the effectiveness of the proposed mode selection method.

  • 3544.
    Zheng, Gan
    et al.
    Department of Electrical and Electronic Engineering, University College London, UK.
    Wong, Kai-Kit
    Department of Electrical and Electronic Engineering, University College London, UK.
    Paulraj, Arogyasvsami
    Information Systems Laboratory, Stanford University, US.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Collaborative-Relay Beamforming with Perfect CSI: Optimum and Distributed Implementation2009In: IEEE Signal Processing Letters, ISSN 1070-9908, E-ISSN 1558-2361, Vol. 16, no 4, p. 257-260Article in journal (Refereed)
    Abstract [en]

    This letter studies the collaborative use of amplify-and-forward (AF) relays to form a virtual multiple-input single-output (MISO) beamforming system with the aid of perfect channel state information (CSI) in a flat-fading channel. In particular, we optimize the relay weights jointly to maximize the received signal-to-noise ratio (SNR) at the destination terminal with both individual and total power constraints at the relays. We show that the optimal collaborative-relay beamforming (CRB) solution achieves the full diversity of a MISO antenna system. Another main contribution of this letter is a distributed algorithm that allows each individual relay to learn its own weight, based on the Karush-Kuhn-Tucker (KKT) analysis.

  • 3545.
    Zheng, Gan
    et al.
    Department of Electrical and Electronic Engineering, University College London, London, WC1E 7JE, UK..
    Wong, Kai-Kit
    Department of Electrical and Electronic Engineering, University College London, London, WC1E 7JE, UK..
    Paulraj, Arogyasvsami
    Information Systems Laboratory, Stanford University, US.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Robust and distributed beamforming2009In: 2009 International Conference on Wireless Communications and Signal Processing, 2009, Vol. WCSP 2009, p. 1629-1633Conference paper (Refereed)
    Abstract [en]

    This paper studies the use of amplify-and-forward (AF) relays for robust beamforming, with the aid of imperfect channel state information (CSI) at the sender. In particular, the maximization of the worst-case signal-to-noise ratio (SNR) at the destination terminal is studied under a bounded spherical region for the norm of CSI error vector. We show that under a condition on the estimated CSI quality, the robust-optimal collaborative-relay beamforming (CRBF) can be obtained by S-Procedure and rank relaxation techniques. In addition, a distributed algorithm is proposed by examining the structure of the optimal CRBF.

  • 3546.
    Zheng, Gan
    et al.
    Department of Electrical and Electronic Engineering, University College London.
    Wong, Kai-Kit
    Department of Electrical and Electronic Engineering, University College London.
    Paulraj, Arogyasvsami
    Information Systems Laboratory, Stanford University, US.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Robust Collaborative-Relay Beamforming2009In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 57, no 8, p. 3130-3143Article in journal (Refereed)
    Abstract [en]

    Relay communications is a promising technique to extend the range of wireless communications by forwarding the message from the sender to the intended destination. While fixed or variable-power relays have been previously investigated, this paper addresses the collaborative use of variable-phase variable-power amplify-and-forward (AF) relays for robust beamforming, with the aid of imperfect channel state information (CSI) at the sender. In particular, the maximization of the worst-case signal-to-noise ratio (SNR) at the destination terminal is studied under a bounded spherical region for the norm of the CSI error vector from the relays to the destination. Our main contribution is that we prove, under a condition on the quality of the estimated CSI, the robust-optimal collaborative-relay beamforming (CRBF) can be obtained by S-Procedure and rank relaxation techniques. In addition, a distributed algorithm is developed by examining the structure of the optimal CRBF solution. Results demonstrate a significant gain of CRBF over non-robust approaches.

  • 3547.
    Zheng, Li-Rong
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Intelligent paper and packaging - Integration of microelectronics technologies into paper and packaging products2007In: International Paperworld IPW, ISSN 1615-1720, no 11, p. 56-58Article in journal (Other academic)
    Abstract [en]

    The integration of microelectronics technologies and intelligent packaging into the paper and packaging products are creating new business opportunities. Intelligent and interactive packaging aims to make traditional food packaging smart, active and user-friendly. he printed optical code or integrated radio-frequency identification (RFID) chips will allow the customers to link the products directly to mobile Internet through the camera or near field communication. The paper can be used as a paper-based biochip for biochemical analysis by integrating biochemical sensors or a sensor array. VINN Excellence iPack Center has been established with the focus on ubiquitous intelligence in paper and packaging. The center will establish collaborations between the forest products industry, the electronics industry and the biomedical industry in the area of intelligent paper and packaging for biomedical applications.

  • 3548.
    Zheng, Tao
    et al.
    Beijing Jiatong University.
    Gidlund, Mikael
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Åkerberg, Johan
    ABB Corporate Research.
    Wireless Arbitration: A Priority-Based Deterministic Media Access Technique for Industrial Wireless Sensor Networks2013Conference paper (Refereed)
  • 3549.
    Zhong, Yang
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Tufvesson, Fredrik
    A dual input-channel software defined receiver platform for GSM WCDMA and Wi-Fi2011In: 2011 International Conference on Wireless Communications and Signal Processing (WCSP), IEEE Communications Society, 2011Conference paper (Refereed)
    Abstract [en]

    In this paper a synchronized dual input-channel multi-mode Software Defined Radio receiver platform that we built originally is presented. The receiver platform compatible with the GSM, WCDMA, and Wi-Fi standards can detect and identify the surrounding base stations and access points. It features wide frequency range, high adaptive sampling rate and especially dual phase coherent receiving channels synchronized both in frequency and time. A detailed structure of the platform and the principle of the software decoders are shown in this paper. Performance of the receiver platform for signal reception is precise and stable. Benefiting from the flexibility of the receiver function, it is not only capable of various functions, such as cognitive radio development and distributed antenna system measurement for academic research, but a dynamic platform for testing new algorithms and ideas.

  • 3550.
    Zhou, Jia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Adding bandwidth specification to a AAA Sever2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Authentication, authorization, and accounting (AAA) are key elements in network security. In many networks, clients can use resources only after they have been authenticated by an authentication server and authorized to use these resources. In some cases the server will also maintain accounting records in order for an operator (a provider of resources) to charge the account/subscriber for using the service. There are four main AAA protocols being used today. Of these RADIUS is the mostly widely used.

    This thesis starts with an introduction to AAA protocols, and then goes in the details of RADIUS. In order to perform a practical evaluation of how the AAA could be improved, FreeRADIUS was selected as the base code for this project; because this implementation is one of the most widely used RADIUS servers. A proposal for how to improve AAA performance is introduced and the implementation steps needed to realize these improvements are shown. Additionally, some experiments have been conducted to show both the correct functioning of the resulting implementation and to examine if there is a performance improvement. Following this some conclusions are drawn based upon a comparison with a traditional AAA server.

    A key element of the change in AAA which is proposed is the use of a non-binary IEEE 802.1x process. This new non-binary solution introduces a new type of AAA server and requires the re-thinking of a number of traditional AAA design decisions. It is expected that this change will have a significant impact, but will require some time for exposure, implementation by others, and a more extensive evaluation that was possible during the period of this thesis project.

    One of the most important conclusions drawn during this thesis is the difficulty of making a change in authentication and authorization, because of the large amount of interaction between both the various protocols and the standards which have been developed for these protocols. Thus one of the difficult aspects of the task is how to introduce a change in a protocol while maintaining backward compatibility for others who have not adopted this change -- without requiring the addition of a protocol version field.

    A second important conclusion is that doing this implementation in three separate parts with different students being responsible for the different parts revealed just how complex the interaction of protocol design decisions are. While a working version of the entire set of changes proved to be impossible, it was observed that the different parts could be decoupled more than initially expected.

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