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  • 1. AG, Valkó
    et al.
    A, Rácz
    G, Fodor
    Voice QoS in third-generation mobile systems1999In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 17, no 1, p. 109-123Article in journal (Refereed)
  • 2.
    Andersson, Mattias
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Schaefer, Rafael F.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Polar Coding for Bidirectional Broadcast Channels with Common and Confidential Messages2013In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 31, no 9, p. 1901-1908Article in journal (Refereed)
    Abstract [en]

    The integration of multiple services such as the transmission of private, common, and confidential messages at the physical layer is becoming important for future wireless networks in order to increase spectral efficiency. In this paper, bidirectional relay networks are considered, in which a relay node establishes bidirectional communication between two other nodes using a decode-and-forward protocol. In the broadcast phase, the relay transmits additional common and confidential messages, which then requires the study of the bidirectional broadcast channel (BBC) with common and confidential messages. This channel generalizes the broadcast channel with receiver side information considered by Kramer and Shamai. Low complexity polar codes are constructed that achieve the capacity region of both the degraded symmetric BBC, and the BBC with common and confidential messages. The use of polar codes allows an intuitive interpretation of how to incorporate receiver side information and secrecy constraints as different sets of frozen bits at the different receivers for an optimal code design. In order to show that the constructed codes achieve capacity, a tighter bound on the cardinality of an auxiliary random variable used in the converse is found using a method by Salehi.

  • 3. Antichi, Gianni
    et al.
    Castro, Ignacio
    Chiesa, Marco
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS, Network Systems Laboratory (NS Lab). Université catholique de Louvain.
    Fernandes, Eder L.
    Lapeyrade, Remy
    Kopp, Daniel
    Han, Jong Hun
    Bruyere, Marc
    Dietzel, Christoph
    Gusat, Mitchell
    Moore, Andrew W.
    Owezarski, Philippe
    Uhlig, Steve
    Canini, Marco
    ENDEAVOUR: A Scalable SDN Architecture For Real-World IXPs2017In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 35, no 11, p. 2553-2562Article in journal (Refereed)
    Abstract [en]

    Innovation in interdomain routing has remained stagnant for over a decade. Recently, Internet eXchange Points (IXPs) have emerged as economically-advantageous interconnection points for reducing path latencies and exchanging ever increasing traffic volumes among, possibly, hundreds of networks. Given their far-reaching implications on interdomain routing, IXPs are the ideal place to foster network innovation and extend the benefits of software defined networking (SDN) to the interdomain level. In this paper, we present, evaluate, and demonstrate ENDEAVOUR, an SDN platform for IXPs. ENDEAVOUR can be deployed on a multi-hop IXP fabric, supports a large number of use cases, and is highly scalable, while avoiding broadcast storms. Our evaluation with real data from one of the largest IXPs, demonstrates the benefits and scalability of our solution: ENDEAVOUR requires around 70% fewer rules than alternative SDN solutions thanks to our rule partitioning mechanism. In addition, by providing an open source solution, we invite everyone from the community to experiment (and improve) our implementation as well as adapt it to new use cases.

  • 4.
    Bagula, Antoine B.
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    On achieveing bandwidth-aware LSP/lambda SP multiplexing/separation in multi-layer networks2007In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 25, no 5, p. 987-1000Article in journal (Refereed)
    Abstract [en]

    We present a new Traffic engineering (TE) model which is based on QoS rerouting and uses hybrid resilience to improve the recovery performance of multi-layer networks where an MPLS network is layered above an MP lambda S network. We formulate the rerouting of the LSPs/lambda SPs as a multi-constrained problem and use its polynomial reduction to find a heuristic solution that can be implemented by standardized constraint-based routing algorithms. This heuristic solution uses a cost-based routing optimization to achieve different network configurations which multiplex/separate bandwidth-aware LSPs/lambda SPs on the network links. We formulate the resilience upon failure as a multi-objective problem consisting of finding a resilience strategy that minimizes recovery operation time and maximizes the LSP/lambda SP restorability. A solution to this problem is proposed where a hybrid resilience framework is used to achieve restoration in the MPLS layer to complement path switching in the MP lambda S layer. We evaluate the performance of the TE model when rerouting the tunnels carrying the traffic offered to a 23- and 31-node networks. Simulation reveals that the hybrid resilience model performs better than classical recovery mechanisms in terms of restorability, quality of rerouting paths and rerouting; stability.

  • 5.
    Bagula, Antoine B
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    On achieving bandwidth aware LSP/λSP multiplexing separation in multi-layer networks2007In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008Article in journal (Other academic)
  • 6.
    Bagula, Antoine B.
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    On achieving bandwidth-aware LSP/LambdasSP multiplexing/separation in multilayer networks2006In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008Article in journal (Refereed)
  • 7.
    Ben Slimane, Slimane
    et al.
    Concordia University.
    Le-Ngoc, Tho
    Maximum likelihood sequence estimation of quadrature pulse-overlapping modulated signals for portable/mobile satellite1992In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 10, no 8Article in journal (Refereed)
  • 8. Berggren, F.
    et al.
    Kim, S. L.
    Jantti, R.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Joint power control and intracell scheduling of DS-CDMA nonreal time data2001In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 19, no 10, p. 1860-1870Article in journal (Refereed)
    Abstract [en]

    The performance of DS-CDMA systems depends on the success in managing interference arising from both intercell and intracell transmissions. Interference management in terms of power control for real time data services like voice has been widely studied and shown to be a crucial component for the functionality of such systems. In this work we consider the problem of supporting downlink nonreal time data services, where in addition to power control, there is also the possibility of controlling the interference by means of transmission scheduling. One such decentralized schedule is to use time division so that users transmit in a one-by-one fashion within each cell. We show that this has merits in terms of saving energy and increasing system capacity. We combine this form of intracell scheduling with a suggested distributed power control algorithm for the intercell interference management. We address its rate of convergence and show that the algorithm converges to a power allocation that supports the nonreal time data users, using the minimum required power while meeting requirements on average data rate. Numerical results indicate a big potential of increased capacity and that a significant amount of energy can be saved with the proposed transmission scheme.

  • 9. Combes, R.
    et al.
    Proutiere, Alexandre
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Dynamic rate and channel selection in cognitive radio systems2015In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 33, no 5, p. 910-921, article id 6914537Article in journal (Refereed)
    Abstract [en]

    In this paper, we investigate dynamic channel and rate selection in cognitive radio systems that exploit a large number of channels free from primary users. In such systems, transmitters may rapidly change the selected (channel, rate) pair to opportunistically learn and track the pair offering the highest throughput. We formulate the problem of sequential channel and rate selection as an online optimization problem and show its equivalence to a structured multiarmed-bandit problem. The structure stems from inherent properties of the achieved throughput as a function of the selected channel and rate. We derive fundamental performance limits satisfied by any channel and rate adaptation algorithm and propose algorithms that achieve (or approach) these limits. In turn, the proposed algorithms optimally exploit the inherent structure of the throughput. We illustrate the efficiency of our algorithms using both test-bed and simulation experiments, in both stationary and nonstationary radio environments. In stationary environments, the packet successful transmission probabilities at the various channel and rate pairs do not evolve over time, whereas in nonstationary environments, they may evolve. In practical scenarios, the proposed algorithms are able to track the best channel and rate quite accurately without the need for any explicit measurement of and feedback on the quality of the various channels.

  • 10.
    Dai, Bin
    et al.
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu 610031, Sichuan, Peoples R China.;Southeast Univ, Natl Mobile Commun Res Lab, Nanjing 210018, Peoples R China..
    Ma, Zheng
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu 610031, Sichuan, Peoples R China..
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Tang, Xiaohu
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu 610031, Sichuan, Peoples R China..
    Fan, Pingzhi
    Southwest Jiaotong Univ, Sch Informat Sci & Technol, Chengdu 610031, Sichuan, Peoples R China..
    Secure Communication Over Finite State Multiple-Access Wiretap Channel With Delayed Feedback2018In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 36, no 4, p. 723-736Article in journal (Refereed)
    Abstract [en]

    Recently, it has been shown that the time-varying multiple-access channel (MAC) with perfect channel state information (CSI) at the receiver and delayed feedback CSI at the transmitters can be modeled as the finite state MAC (FS-MAC) with delayed state feedback, where the time variation of the channel is characterized by the statistics of the underlying state process. To study the fundamental limit of the secure transmission over multi-user wireless communication systems, we re-visit the FS-MAC with delayed state feedback by considering an external eavesdropper, which we call the finite state multipleaccess wiretap channel (FS-MAC-WT) with delayed feedback. The main contribution of this paper is to show that taking full advantage of the delayed channel output feedback helps to increase the secrecy rate region of the FS-MAC-WT with delayed state feedback. Moreover, by a degraded Gaussian fading example, we show the effects of feedback delay and channel memory on the secrecy sum rate of the FS-MAC-WT with delayed feedback.

  • 11.
    De Angelis, Alessio
    et al.
    University of Perugia.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Mobile Node Localization via Pareto Optimization: Algorithm and Fundamental Performance Limitations2015In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 33, no 7, p. 1288-1316Article in journal (Refereed)
    Abstract [en]

    Accurate estimation of the position of network nodes is essential, e.g., in localization, geographic routing, and vehicular networks. Unfortunately, typical positioning techniques based on ranging or on velocity and angular measurements are inherently limited. To overcome the limitations of specific positioning techniques, the fusion of multiple and heterogeneous sensor information is an appealing strategy. In this paper, we investigate the fundamental performance of linear fusion of multiple measurements of the position of mobile nodes, and propose a new distributed recursive position estimator. The Cramer-Rao lower bounds for the parametric and a-posteriori cases are investigated. The proposed estimator combines information coming from ranging, speed, and angular measurements, which is jointly fused by a Pareto optimization problem where the mean and the variance of the localization error are simultaneously minimized. A distinguished feature of the method is that it assumes a very simple dynamical model of the mobility and therefore it is applicable to a large number of scenarios providing good performance. The main challenge is the characterization of the statistical information needed to model the Fisher information matrix and the Pareto optimization problem. The proposed analysis is validated by Monte Carlo simulations, and the performance is compared to several Kalman-based filters, commonly employed for localization and sensor fusion. Simulation results show that the proposed estimator outperforms the traditional approaches that are based on the extended Kalman filter when no assumption on the model of motion is used. In such a scenario, better performance is achieved by the proposed method, but at the price of an increased computational complexity.

  • 12.
    Du, Jinfeng
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Médard, Muriel
    Department of Electrical Engineering and Computer Science, MIT.
    Wireless multicast relay networks with limited-rate source-conferencing2013In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 31, no 8, p. 1390-1401Article in journal (Refereed)
    Abstract [en]

    We investigate capacity bounds for a wireless multicast relay network where two sources simultaneously multicast to two destinations with the help of a full-duplex relay node. The two sources and the relay use the same channel resources (i.e. co-channel transmission). We assume Gaussian channels with time-invariant channel gains which are known by all nodes. The two source nodes are connected by orthogonal limited-rate error-free conferencing links. By extending the proof of the converse for the Gaussian relay channel and introducing two lemmas on conditional (co-)variance, we present two genie-aided outer bounds of the capacity region for this multicast relay network. We extend noisy network coding to use source cooperation with the help of the theory of network equivalence. We also propose a new coding scheme, partial-decode-and- forward based linear network coding, which is essentially a hybrid scheme utilizing rate-splitting and messages conferencing at the source nodes, partial decoding and linear network coding at the relay, and joint decoding at each destination. A low-complexity alternative scheme, analog network coding based on amplify-and-forward relaying, is also investigated and shown to benefit greatly from the help of the conferencing links and can even outperform noisy network coding when the coherent combining gain is dominant.

  • 13.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Gkatzikis, Lazaros
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Xiag, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Energy Efficient Sensor Activation for Water Distribution Networks Based on Compressive Sensing2015In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 33, no 12, p. 2997-3010Article in journal (Refereed)
    Abstract [en]

    The recent development of low cost wireless sensors enables novel internet-of-things (IoT) applications, such as the monitoring of water distribution networks. In such scenarios, the lifetime of the wireless sensor network (WSN) is a major concern, given that sensor node replacement is generally inconvenient and costly. In this paper, a compressive sensing-based scheduling scheme is proposed that conserves energy by activating only a small subset of sensor nodes in each timeslot to sense and transmit. Compressive sensing introduces a cardinality constraint that makes the scheduling optimization problem particularly challenging. Taking advantage of the network topology imposed by the IoT water monitoring scenario, the scheduling problem is decomposed into simpler subproblems, and a dynamic-programming-based solution method is proposed. Based on the proposed method, a solution algorithm is derived, whose complexity and energy-wise performance are investigated. The complexity of the proposed algorithm is characterized and its performance is evaluated numerically via an IoT emulator of water distribution networks. The analytical and numerical results show that the proposed algorithm outperforms state-of-the-art approaches in terms of energy consumption, network lifetime, and robustness to sensor node failures. It is argued that the derived solution approach is general and it can be potentially applied to more IoT scenarios such as WSN scheduling in smart cities and intelligent transport systems.

  • 14.
    Du, Rong
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Xiao, Ming
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Optimal Node Deployment and Energy Provision for Wirelessly Powered Sensor Networks2018In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 2, p. 407-423Article in journal (Refereed)
    Abstract [en]

    In a typical wirelessly powered sensor network (WPSN), wireless chargers provide energy to sensor nodes by using wireless energy transfer (WET). The chargers can greatly improve the lifetime of a WPSN using energy beamforming by a proper charging scheduling of energy beams. However, the supplied energy still may not meet the demand of the energy of the sensor nodes. This issue can be alleviated by deploying redundant sensor nodes, which not only increase the total harvested energy, but also decrease the energy consumption per node provided that an efficient  scheduling of the sleep/awake of the nodes is performed. Such a problem of joint optimal sensor deployment, WET scheduling, and node activation is posed and investigated in this paper. The problem is an integer optimization that is challenging due to the binary decision variables and non-linear constraints. Based on the analysis of the necessary condition such that the WPSN be immortal, we decouple the original problem into a node deployment problem and a charging and activation scheduling problem. Then, we propose an algorithm and prove that it achieves the optimal solution under a mild condition. The simulation results show that the proposed algorithm reduces the needed nodes to deploy by approximately 16%, compared to a random-based approach. The simulation also shows if the battery buffers are large enough, the optimality condition will be easy to meet.

  • 15.
    Dwivedi, Satyam
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    De Angelis, Alessio
    Zachariah, Dave
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Joint Ranging and Clock Parameter Estimation by Wireless Round Trip Time Measurements2015In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 33, no 11, p. 2379-2390Article in journal (Refereed)
    Abstract [en]

    In this paper, we develop a new technique for estimating fine clock errors and range between two nodes simultaneously by two-way time-of-arrival measurements using impulse-radio ultrawideband signals. Estimators for clock parameters and the range are proposed, which are robust with respect to outliers. They are analyzed numerically and by means of experimental measurement campaigns. The technique and derived estimators achieve accuracies below 1 Hz for frequency estimation, below 1 ns for phase estimation, and 20 cm for range estimation, at a 4-m distance using 100-MHz clocks at both nodes. Therefore, we show that the proposed joint approach is practical and can simultaneously provide clock synchronization and positioning in an experimental system.

  • 16.
    Eriksson, Magnus
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Dynamic Single Frequency Networks2001In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 19, no 10, p. 1905-1914Article in journal (Refereed)
    Abstract [en]

    Wireless asymmetric Internet access with a downlink peak bit rate of 10 to 30 Mb/s can be achieved by using the terrestrial digital video broadcasting system (DVB-T) as a supplemental downlink together with today's cellular systems. This paper is a study of dynamic radio resource management on a packet-by-packet basis for this broadband downlink. The dynamic single frequency networks (DSFN) scheme is evaluated. It exploits the macrodiversity capability of the OFDM modulation scheme. The transmitters are dynamically divided into groups of transmitters that send the same information at the same channel frequency simultaneously. The fairly shared spectrum efficiency (FSSE), in bits per second per Hertz per site, which is a combined measurement of maximum throughput and fairness, is evaluated for best-effort traffic. DSFN improves the FSSE by 100% to 370%, for a certain set of test cases, in comparison to the dynamic packet assignment (DPA) scheme, which combines packet scheduling with dynamic channel assignment (DCA).

  • 17.
    Fiorani, Matteo
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Tombaz, Sibel
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Farias, Fabricio S.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Monti, Paolo
    Joint Design of Radio and Transport for Green Residential Access Networks2016In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 34, no 4, p. 812-822Article in journal (Refereed)
    Abstract [en]

    d Mobile networks are the largest contributor to the carbon footprint of the telecom sector and their contribution is expected to rapidly increase in the future due to the foreseen traffic growth. Therefore, there is an increasing urgency in the definition of green mobile network deployment strategies. This paper proposes a four-step design and power assessment methodology for mobile networks, taking into consideration both radio and transport segments. A number of mobile network deployment architectures for urban residential areas based on different radio (i.e., macro base station, distributed indoor radio, femto cell) and transport (i.e., microwave, copper, optical fiber) technologies are proposed and evaluated to identify the most energy efficient solution. The results show that with low traffic the conventional macro base station deployment with microwave based backhaul is the best option. However, with higher traffic values heterogeneous networks withmacro base stations and indoor small cells are more energy efficient. The best small cell solution highly depends on the transport network architecture. In particular, our results show that a femto cell based deployment with optical fiber backhaul is the most energy efficient, even if a distributed indoor radio architecture (DRA) deployment with fiber fronthaul is also a competitive approach.

  • 18.
    Gabry, Frédéric
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Li, Nan
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Schrammar, Nicolas
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Girnyk, Maksym
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Rasmussen, Lars K.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    On the Optimization of the Secondary Transmitter's Strategy in Cognitive Radio Channels with Secrecy2014In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 32, no 3, p. 451-463Article in journal (Refereed)
    Abstract [en]

    This paper investigates cooperation for secrecy in cognitive radio networks. In particular, we consider a four-node cognitive scenario where the secondary receiver is treated as a potential eavesdropper with respect to the primary transmission. The cognitive transmitter can help the primary transmission, and it should also ensure that the primary message is not leaked to the secondary user. We consider two cognitive scenarios depending on whether the secondary transmitter knows the primary message or not. In the first case, the secondary transmitter is unaware of the primary transmitter's message and acts as a helping interferer to enhance the secrecy of the primary transmission, whereas in the second case, relaying of the primary message is also within its capabilities. First, we find achievable rate regions for these two scenarios in the case of AWGN channels. We then investigate three different optimization problems: the maximization of the primary rate, the maximization of the secondary rate and the minimization of the secondary transmit power. For these optimization problems, we find closed-form expressions in important special cases. Furthermore, we analyze the cooperation between the primary and secondary transmitters from a game-theoretic perspective. We model their interaction as a Stackelberg game, for which we define and find the Stackelberg equilibrium. Finally, we use numerical examples to illustrate the rate regions, the three optimizations, and the impact of the Stackelberg game on the achievable rates and on the transmission strategies of the secondary transmitter.

  • 19. Gautam, S.
    et al.
    Vu, T. X.
    Chatzinotas, S.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Cache-Aided Simultaneous Wireless Information and Power Transfer (SWIPT) With Relay Selection2019In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 1, p. 187-201Article in journal (Refereed)
  • 20. Gharanjik, A.
    et al.
    Shankar, M. R. B.
    Zimmer, F.
    Ottersten, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Centralized Rainfall Estimation Using Carrier to Noise of Satellite Communication Links2018In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 36, no 5, p. 1065-1073Article in journal (Refereed)
  • 21.
    Ghauch, Hadi
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Kim, Taejoon
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Sum-Rate Maximization in Sub-28-GHz Millimeter-Wave MIMO Interfering Networks2017In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 35, no 7, p. 1649-1662Article in journal (Refereed)
    Abstract [en]

    MIMO systems in the lower part of the millimetre-wave (mmWave) spectrum band (i.e., below 28 GHz) do not exhibit enough directivity and selectively, as compared to their counterparts in higher bands of the spectrum (i.e., above 60 GHz), and thus still suffer from the detrimental effect of interference, on the system sum rate. As such systems exhibit large numbers of antennas and short coherence times for the channel, traditional methods of distributed coordination are ill-suited, and the resulting communication overhead would offset the gains of coordination. In this paper, we propose algorithms for tackling the sum-rate maximization problem that are designed to address the above-mentioned limitations. We derive a lower bound on the sum rate, a so-called difference of log and trace (DLT) bound, shed light on its tightness, and highlight its decoupled nature at both the transmitters and receivers. Moreover, we derive the solution to each of the subproblems that we dub non-homogeneous waterfilling (a variation on the MIMO waterfilling solution), and underline an inherent desirable feature: its ability to turn-OFF streams exhibiting low SINR, and contribute to greatly speeding up the convergence of the proposed algorithm. We then show the convergence of the resulting algorithm, max-DLT, to a stationary point of the DLT bound. Finally, we rely on extensive simulations of various network configurations, to establish the fast-converging nature of our proposed schemes, and thus their suitability for addressing the short coherence interval, as well as the increased system dimensions, arising when managing interference in lower bands of the mmWave spectrum. Moreover, our results suggest that interference management still brings about significant performance gains, especially in dense deployments.

  • 22.
    Gross, James
    et al.
    IEEE, Germany .
    Geerdes, Hans-Florian
    TU Berlin.
    Karl, Holger
    Universitaet Paderborn.
    Wolisz, Adam
    TU Berlin.
    Performance Analysis of Dynamic OFDMA Systems with Inband Signaling2006In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 24, no 3, p. 427-436Article in journal (Refereed)
    Abstract [en]

    Within the last decade, the orthogonal frequency-division multiplexing (OFDM) transmission scheme has become part of several standards for wireless systems. Today, OFDM is even a candidate for fourth-generation wireless systems. It is well known that dynamic OFDMA systems potentially increase the spectral efficiency. They exploit diversity effects in time, space, and frequency by assigning system resources periodically to terminals. Informing the terminals about new assignments creates a signaling overhead. Up to now, this overhead has not been taken into account in studies on dynamic orthogonal frequency-division multiplexing access (OFDMA) systems. Yet this is crucial for a realistic notion of the performance achieved by dynamic approaches. In this paper, we close this gap. We introduce two forms of representing the signaling information and discuss how these affect system performance. The study of the signaling impact on the performance is conducted for an exemplary dynamic approach. We find that the throughput behavior of dynamic OFDMA systems is significantly influenced by the signaling overhead. In many situations, neglecting the overhead leads to wrong performance conclusions. Also, the performance difference between dynamic and static schemes is now much more sensible to the specific parameter set of the transmission scenario (e.g., frame length, subcarrier number, etc.). This leads to the proposal of access points which should adapt certain system parameters in order to provide optimal performance.

  • 23.
    Guo, Dongning
    et al.
    National University of Singapore.
    Rasmussen, Lars Kildehöj
    National University of Singapore.
    Lim, Teng Joon
    National University of Singapore.
    Linear parallel interference cancellation in long-code CDMA multiuser detection1999In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 17, no 12, p. 2074-2081Article in journal (Refereed)
  • 24.
    Henrik, Forssell
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Al-Zubaidy, Hussein
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Physical Layer Authentication in Mission-Critical MTC Networks: A Security and Delay Performance Analysis2019In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 4, p. 795-808Article in journal (Refereed)
    Abstract [en]

    We study the detection and delay performance impacts of a feature-based physical layer authentication (PLA) protocol in mission-critical machine-type communication (MTC) networks. The PLA protocol uses generalized likelihood-ratio testing based on the line-of-sight (LOS), single-input multiple- output channel-state information in order to mitigate imper- sonation attempts from an adversary node. We study the de- tection performance, develop a queueing model that captures the delay impacts of erroneous decisions in the PLA (i.e., the false alarms and missed detections), and model three different adversary strategies: data injection, disassociation, and Sybil attacks. Our main contribution is the derivation of analytical delay performance bounds that allow us to quantify the delay introduced by PLA that potentially can degrade the performance in mission-critical MTC networks. For the delay analysis, we utilize tools from stochastic network calculus. Our results show that with a sufficient number of receive antennas (approx. 4-8) and sufficiently strong LOS components from legitimate devices, PLA is a viable option for securing mission-critical MTC systems, despite the low latency requirements associated to corresponding use cases. Furthermore, we find that PLA can be very effective in detecting the considered attacks, and in particular, it can significantly reduce the delay impacts of disassociation and Sybil attacks.

  • 25. Ho, Pin-Han
    et al.
    Shen, Gangxiang
    Subramaniam, Suresh
    Mouftah, Hussein T.
    Qiao, Chunming
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Guest Editorial Energy-Efficiency in Optical Networks2014In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 32, no 8, p. 1521-1523Article in journal (Other academic)
  • 26. Hu, Bin
    et al.
    Land, Ingmar
    Rasmussen, Lars Kildehöj
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Piton, Romain
    Fleury, Bernard H.
    A divergence minimization approach to joint multiuser decoding for coded CDMA2008In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 26, no 3, p. 432-445Article in journal (Refereed)
    Abstract [en]

    In this paper, a theoretical framework of divergence minimization (DM) is applied to derive iterative receiver algorithms for coded CDMA systems. The DM receiver obtained performs joint channel estimation, multiuser decoding, and noisecovariance estimation. While its structure is similar to that of many ad-hoc receivers in the literature, the DM receiver is the result of applying a formal framework for optimization without further simplifications,namely the DM approach with a factorizable auxiliary model distribution. The well-known expectation-maximization (EM) algorithm and space-alternating generalized expectation-maximization (SAGE) algorithm are special cases of degenerate model distributions within the DM framework. Furthermore, many ad-hoc receiver structures from literature are shown to represent approximations of the proposed DM receiver. The DM receiver has four interesting properties that all result directly from applying the formal framework: (i) The covariances of all estimates involved are taken into account. (ii) The residual interference after interference cancellation is handled by the noise-covariance estimation as opposed to by LMMSE filters in other receivers. (iii) Posterior probabilities of the code symbols are employed rather than extrinsic probabilities. (iv) The iterative receiver is guaranteed to converge in divergence. The theoretical insights are illustrated by simulation results.

  • 27.
    Huang, Yongming
    et al.
    Southeast Univ, Sch Informat Sci & Engn, Natl Mobile Commun Res Lab, Nanjing 210096, Jiangsu, Peoples R China..
    Zhang, Jianjun
    Southeast Univ, Sch Informat Sci & Engn, Natl Mobile Commun Res Lab, Nanjing 210096, Jiangsu, Peoples R China..
    Xiao, Ming
    KTH, School of Electrical Engineering (EES).
    Constant Envelope Hybrid Precoding for Directional Millimeter-Wave Communications2018In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 36, no 4, p. 845-859Article in journal (Refereed)
    Abstract [en]

    Millimeter wave (mmwave) communication has attracted increasing attention owing to its abundant spectrum resource. The short wavelength at mmwave frequencies facilitates placing a large number of antennas in a small space, and the mmwave channels are likely to be sparse in the directions. These two new features promise enhanced security by directional precoding. To explore this potential, we investigate the design of directional hybrid digital and analog precoding for the multiuser mmwave communication system with multiple eavesdroppers. Particularly, we consider two cost-efficient sub-connected hybrid architectures, i.e., multi-subarray architecture and switched phased- array architecture, and optimize the hybrid precoding under per-antenna constant envelope (CE) constraints. The goal of our design is to guarantee the receive quality of the legitimate users while minimizing the power leaked to the eavesdroppers, so as to realize a directional transmission for a general mmwave channel. The resulting problems are very challenging due to the nonlinear CE constraints and binary integer constraint from antenna selection. To address them, we leverage exact penalty function methods to find efficient solutions to the CE hybrid directional precoding. Our analysis shows that the proposed algorithm is able to converge to a stationary point under some mild conditions. Simulation results are finally provided to confirm the effectiveness of the proposed schemes and their superiority over the existing schemes under both single-path and multi-path mmwave channels.

  • 28. Jang, Insun
    et al.
    Suh, Dongeun
    Pack, Sangheon
    Dan, György
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Joint Optimization of Service Function Placement and Flow Distribution for Service Function Chaining2017In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 35, no 11, p. 2532-2541Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the problem of optimal dynamic service function (SF) placement and flow routing in a SF chaining (SFC) enabled network. We formulate a multi-objective optimization problem to maximize the acceptable flow rate and to minimize the energy cost for multiple service chains. We transform the multi-objective optimization problem into a single-objective mixed integer linear programming (MILP) problem, and prove that the problem is NP-hard. We propose a polynomial time algorithm based on linear relaxation and rounding to approximate the optimal solution of the MILP. Extensive simulations are conducted to evaluate the effects of the energy budget, the network topology, and the amount of server resources on the acceptable flow rate. The results demonstrate that the proposed algorithm can achieve near-optimal performance and can significantly increase the acceptable flow rate and the service capacity compared to other algorithms under an energy cost budget.

  • 29.
    Janssen, Gerard J. M.
    et al.
    Telecommunication and Traffic-Control Systems Group, Department of Information Technology and Systems, Delft University of Technology, 2600 GA Delft, The Netherlands.
    Ben Slimane, Slimane
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Symbol error probability analysis of a multiuser detector for M-PSK signals based on successive Cancellation2002In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 20, no 2, p. 330-338Article in journal (Refereed)
    Abstract [en]

    A narrow-band multiuser receiver based on successive signal detection and subtraction, is considered in this paper. The symbol error probability (SEP) for M-PSK modulated signals is evaluated and analytical approximations for the SEP of the individual signals are presented and compared with results obtained from simulations. For geometrically related signal amplitudes, a constant minimum distance can be guaranteed independent of the number of signals. The required amplitude ratio is shown to be related to and the number of co-channel signals. Optimizing the transmitted power for the different signals while ensuring the same SEP is then addressed and closed-form expressions of the signal amplitude ratios are derived. The effect of inaccurately estimated signal parameters due to noise is also analyzed. SEP results are presented for synchronous signals in an additive white Gaussian noise environment.

  • 30.
    Jiang, Xiaolin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Pang, Zhibo
    Zhan, Ming
    Dzung, Dacfey
    Luvisotto, Michele
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Packet Detection by a Single OFDM Symbol in URLLC for Critical Industrial Control: A Realistic Study2019In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 4, p. 933-946Article in journal (Refereed)
    Abstract [en]

    Ultra-high reliable and low-latency communication (URLLC)is envisaged to support emerging applications with strict latency and reliability requirements. Critical industrial control is among the most important URLLC applications where the stringent requirements make the deployment of wireless networks critical, especially as far as latency is concerned. Since the amount of data exchanged in critical industrial communications is generally small, an effective way to reduce the latency is to minimize the packet's synchronization overhead, starting from the physical layer (PHY). This paper proposes to use a short one-symbol PHY preamble for critical wireless industrial communications, reducing significantly the transmission latency with respect to other wireless standards. Dedicated packet detection and synchronization algorithms are discussed, analyzed, and tuned to ensure that the required reliability level is achieved with such extremely short preamble. Theoretical analysis, simulations, and experiments show that detection error rates smaller than 10(-6) can be achieved with the proposed preamble while minimizing the latencies.

  • 31.
    Jiang, Xiaolin
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Pang, Zhibo
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Zhan, Ming
    KTH.
    Dzung, Dacfey
    Luvisotto, Michele
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Network and Systems engineering.
    Packet Detection by Single OFDM Symbol in URLLC for Critical Industrial Control: a Realistic Study2018In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008Article in journal (Other academic)
  • 32. Johansson, Björn
    et al.
    Soldati, Pablo
    Johansson, Mikael
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Mathematical decomposition techniques for distributed cross-layer optimization of data networks2006In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 24, no 8, p. 1535-1547Article in journal (Refereed)
  • 33.
    Jäntti, Riku
    et al.
    Faculty of Computer Science Department of Information Technology University of Vaasa FIN-65101, Vaasa, FINLAND.
    Kim, Seong-Lyun
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Second-Order Power Control with Asymptotically Fast Convergence2000In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 18, no 3, p. 447-457Article in journal (Refereed)
    Abstract [en]

    This paper proposes a distributed power control algorithm that uses power levels of both current and previous iterations for power update. The algorithm is developed by applying the successive overrelaxation method to the power control problem. The gain from such a second-order algorithm is in faster convergence. Convergence analysis of the algorithm in case of feasible systems is provided in this paper. Using the distributed constrained power control (DCPC) as a reference algorithm, we carried out computational experiments on a DS-CDMA system. The results indicate that our algorithm significantly enhances the convergence speed of power control. A practical version of the proposed algorithm is provided and compared with the bang-bang type algorithm used in the IS-95 and the WCDMA systems. The results show that our algorithm also has a high potential for increasing the radio network capacity. Our analysis assumes that the system is feasible in the sense that we can support every active user by an optimal power control. When the system becomes infeasible because of high traffic load, it calls for other actions such as transmitter removal, which is beyond the scope of the present paper.

  • 34.
    Karlsson, Gunnar
    et al.
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    Almeroth, Kevin
    Univ Calif Santa Barbara, Dept Comp Sci, Santa Barbara, CA 93106 USA..
    Fall, Kevin
    Intel Res Berkeley, Berkeley, CA USA..
    May, Martin
    ETH, Comp Engn & Networks Lab, Zurich, Switzerland..
    Yates, Roy
    Rutgers State Univ, WINLAB, Piscataway, NJ USA..
    Delay and disruption tolerant wireless communication2008In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 26, no 5, p. 745-747Article in journal (Other academic)
  • 35.
    Kim, Thanh Tung
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Caire, G.
    USC.
    On Cooperative Source Transmission with Partial Rate and Power Control2008In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 26, no 8, p. 1408-1418Article in journal (Refereed)
    Abstract [en]

    The problem of transmitting a Gaussian source over a half-duplex fading relay channel with limited channel state feedback is studied. It is shown that under a short-term power constraint, combining a simple feedback scheme with separate source and channel coding outperforms the best known no-feedback strategies even with only a few bits of feedback information. Partial power control is shown to be instrumental in achieving a very fast decaying average distortion, especially in the regime of high bandwidth ratios. Performance limitation due to the lack of full channel state information at the destination is also investigated, where the degradation in terms of the distortion exponent is shown to be significant. However, even in such restrictive scenarios, using partial feedback still yields distortion exponents superior to any no-feedback schemes.

  • 36. Lee, Hyojung
    et al.
    Jang, Hyeryung
    Cho, Jeong-woo
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Network Systems Laboratory (NS Lab).
    Yi, Yung
    Traffic Scheduling and Revenue Distribution Among Providers in the Internet: Tradeoffs and Impacts2017In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 35, no 2, p. 421-431Article in journal (Refereed)
    Abstract [en]

    The Internet consists of economically selfish players in terms of access/transit connection and content distribution. Such selfish behaviors often lead to techno-economic inefficiencies, such as unstable peering and revenue imbalance. Recent research results suggest that cooperation-based fair revenue sharing, i.e., multi-level Internet service provider (ISP) settlements, can be a candidate solution to avoid unfair revenue share. However, it has been under-explored whether selfish ISPs actually cooperate or not (often referred to as the stability of coalition), because they may partially cooperate or even do not cooperate, depending on how much revenue is distributed to each individual ISP. In this paper, we study this stability of coalition in the Internet, where our aim is to investigate the conditions under which ISPs cooperate under different regimes on the traffic demand and network bandwidth. We first consider the under-demanded regime, i.e., network bandwidth exceeds traffic demand, where revenue sharing based on Shapley value leads ISPs to entirely cooperate, i.e., stability of the grand coalition. Next, we consider the over-demanded regime, i.e., traffic demand exceeds network bandwidth, where there may exist some ISPs who deviate from the grand coalition. In particular, this deviation depends on how users' traffic is handled inside the network, for which we consider three traffic scheduling policies having various degrees of content-value preference. We analytically compare those three scheduling policies in terms of network neutrality, and stability of cooperation that provides useful implications on when and how multi-level ISP settlements help and how the Internet should be operated for stable peering and revenue balance among ISPs.

  • 37.
    Lim, Teng Joon
    et al.
    National University of Singapore.
    Rasmussen, Lars Kildehöj
    National University of Singapore.
    Sugimoto, Hiroki
    OKI Techno Center, Singapore.
    An asynchronous multiuser CDMA detector based on the Kalman filter1998In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 16, no 9, p. 1711-1722Article in journal (Refereed)
  • 38. Liu, Yang
    et al.
    Wang, Gongpu
    Xiao, Ming
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Zhong, Zhangdui
    Spectrum Sensing and Throughput Analysis for Cognitive Two-Way Relay Networks With Multiple Transmit Powers2016In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 34, no 11, p. 3038-3047Article in journal (Refereed)
    Abstract [en]

    Existing studies on cognitive two-way relay networks assume that the primary users (PUs) transmit data with two power levels. In practice, it is possible that the PUs may adopt multiple power levels to maximize their throughputs or to compensate for wireless link fading. In such a scenario, there exist two key problems: one is the detection accuracy for the secondary users (SUs), and the other is the throughput tradeoff between PUs and SUs. To address the detection accuracy challenge, we propose a cooperative soft-combination-based energy detector and demonstrate its benefit over other hard-combination-based detectors. To solve the throughput tradeoff problem, we derive the throughput expressions for both PUs and SUs and analyze the impact of our detection accuracy on the throughputs. It is shown that the SU's throughput varies with the number of the PU's transmit power levels and achieves a maximum value when the number is small. We also find that increasing the detection capability of the SU reduces its own throughput, while increases the PU's throughput.

  • 39.
    Najari Moghadam, Nima
    et al.
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Shokri-Ghadikolaei, Hossein
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Fodor, Gabor
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Network and Systems engineering.
    Pilot Precoding and Combining in Multiuser MIMO Networks2017In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. June, no 6Article in journal (Refereed)
    Abstract [en]

    Although the benefits of precoding and combining data signals are widely recognized, the potential of these techniques for pilot transmission is not fully understood. This is particularly relevant for multiuser multiple-input multiple-output(MU-MIMO) cellular systems using millimeter-wave (mmWave)communications, where multiple antennas have to be used both at the transmitter and the receiver to overcome the severe path loss.In this paper, we characterize the gains of pilot precoding and combining in terms of channel estimation quality and achievable data rate. Specifically, we consider three uplink pilot transmission scenarios in a mmWave MU-MIMO cellular system: 1) non-precoded and uncombined, 2) precoded but uncombined, and3) precoded and combined. We show that a simple precoder that utilizes only the second-order statistics of the channel reduces the variance of the channel estimation error by a factor that is proportional to the number of user equipment (UE) antennas.We also show that using a linear combiner design based on the second-order statistics of the channel significantly reduces multiuser interference and provides the possibility of reusing some pilots. Specifically, in the large antenna regime, pilot preceding and combining help to accommodate a large number ofUEs in one cell, significantly improve channel estimation quality, boost the signal-to-noise ratio of the UEs located close to the cell edges, alleviate pilot contamination, and address the imbalanced coverage of pilot and data signals.

  • 40.
    Natalino, Carlos
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Chiaraviglio, L.
    Idzikowski, F.
    Francês, C. R. L.
    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).
    Optimal lifetime-aware operation of green optical backbone networks2016In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, ISSN 0733-8716, Vol. 34, no 12, p. 3915-3926, article id 2611879Article in journal (Refereed)
    Abstract [en]

    This paper targets the lifetime-aware management of a set of optical line amplifiers (OLAs) in an optical network exploiting sleep mode (SM) in order to save energy. We first present a simple model to predict the OLA lifetime. We then provide different mixed-integer linear programming (MILP) formulations, which jointly consider energy saving and lifetime. The proposed MILP formulations are then solved on different realistic scenarios, by taking into account the spatial and temporal variations of traffic demands. Results show that our lifetime-aware approach outperforms classical energy saving ILP formulations, which instead tend to notably decrease the OLA lifetime. More important, the proposed approaches can achieve a good lifetime performance without consuming significantly more energy than purely energy-aware strategies.

  • 41.
    Pacifici, Valentino
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Convergence in Player-Specific Graphical Resource Allocation Games2012In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 30, no 11, p. 2190-2199Article in journal (Refereed)
    Abstract [en]

    As a model of distributed resource allocation in networked systems, we consider resource allocation games played over a influence graph. The influence graph models limited interaction between the players due to, e. g., the network topology: the payoff that an allocated resource yields to a player depends only on the resources allocated by her neighbors on the graph. We prove that pure strategy Nash equilibria (NE) always exist in graphical resource allocation games and we provide a linear time algorithm to compute equilibria. We show that these games do not admit a potential function: if there are closed paths in the influence graph then there can be best reply cycles. Nevertheless, we show that from any initial allocation of a resource allocation game it is possible to reach a NE by playing best replies and we provide a bound on the maximal number of update steps required. Furthermore we give sufficient conditions in terms of the influence graph topology and the utility structure under which best reply cycles do not exist. Finally we propose an efficient distributed algorithm to reach an equilibrium over an arbitrary graph and we illustrate its performance on different random graph topologies.

  • 42.
    Pacifici, Valentino
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Dán, György
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Distributed Caching Algorithms for Interconnected Operator CDNs2016In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 35, no 2, p. 380-391Article in journal (Refereed)
    Abstract [en]

    Fixed and mobile network operators increasingly deploy managed content distribution networks (CDNs) with the objective of reducing the traffic on their transit links and to improve their customers' quality of experience. As network operator managed CDNs (nCDNs) become commonplace, operators will likely provide common interfaces to interconnect their nCDNs for mutual benefit, as they do with peering today. In this paper, we consider the problem of using distributed algorithms for computing a cache allocation for nCDNs. We show that if every network operator aims to minimize its cost and bilateral payments are not allowed, then it may be impossible to compute a cache allocation. For the case when bilateral payments are possible, we propose two distributed algorithms, the aggregate value compensation and the object value compensation algorithms, which differ in terms of the level of parallelism they allow and in terms of the amount of information exchanged between nCDNs. We prove that the algorithms converge, and we propose a scheme to ensure ex-post individual rationality. Simulations performed on a real autonomous system-level network topology and synthetic topologies show that the algorithms have geometric rate of convergence, and scale well with the graphs' density and the nCDN capacity.

  • 43. Papadimitratos, Panagiotis
    et al.
    Haas, Z. J.
    Secure Data Communication in Mobile Ad Hoc Networks2006In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 24, no 2, p. 343-356Article in journal (Refereed)
    Abstract [en]

    We address the problem of secure and fault-tolerant communication in the presence of adversaries across a multihop wireless network with frequently changing topology. To effectively cope with arbitrary malicious disruption of data transmissions, we propose and evaluate the secure message transmission (SMT) protocol and its alternative, the secure single-path (SSP) protocol. Among the salient features of SMT and SSP is their ability to operate solely in an end-to-end manner and without restrictive assumptions on the network trust and security associations. As a result, the protocols are applicable to a wide range of network architectures. We demonstrate that highly reliable communication can be sustained with small delay and small delay variability, even when a substantial portion of the network nodes systematically or intermittently disrupt communication. SMT and SSP robustly detect transmission failures and continuously configure their operation to avoid and tolerate data loss, and to ensure the availability of communication. This is achieved at the expense of moderate transmission and routing overhead, which can be traded off for delay. Overall, the ability of the protocols to mitigate both malicious and benign faults allows fast and reliable data transport even in highly adverse network environments.

  • 44.
    Papadimitratos, Panagiotis
    et al.
    Swiss Federal Institute of Technology in Lausanne, Switzerland .
    Luo, J.
    Hubaux, J. -P
    Randomized Countermeasure Against Parasitic Adversaries in Wireless Sensor Networks2010In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 28, no 7, p. 1036-1045Article in journal (Refereed)
    Abstract [en]

    Due to their limited capabilities, wireless sensor nodes are subject to physical attacks that are hard to defend against. In this paper, we first identify a typical attacker, called parasitic adversary, who seeks to exploit sensor networks by obtaining measurements in an unauthorized way. As a countermeasure, we first employ a randomized key refreshing: with low communication cost, it aims at confining (but not eliminating) the effects of the adversary. Moreover, our low-complexity solution, GossiCrypt, leverages on the large scale of sensor networks to protect data confidentiality, efficiently and effectively. GossiCrypt applies symmetric key encryption to data at their source nodes; and it applies re-encryption at a randomly chosen subset of nodes en route to the sink. The combination of randomized key refreshing and GossiCrypt protects data confidentiality with a probability of almost 1; we show this analytically and with simulations. In addition, the energy consumption of GossiCrypt is lower than a public-key based solution by several orders of magnitude.

  • 45.
    Parkvall, Stefan
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ström, Erik G
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ottersten, Björn
    KTH, Superseded Departments, Signals, Sensors and Systems.
    The impact of timing errors on the performance of linear DS-CDMA receivers1996In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 14, no 8, p. 1660-1668Article in journal (Refereed)
    Abstract [en]

    In this paper, an asynchronous direct-sequence code-division multiple-access (DS-CDMA) communication system operating over an additive white Gaussian noise (AWGN) channel is considered. In many applications, the near-far problem can be the limiting factor for the capacity of a DS-CDMA system. Several near-far resistan t receivers have, therefore, been proposed (e.g., the decorrelating receiver). These receivers assume perfect knowledge of the propagation delay from all users to the receiver. In practice, the delays are estimated and therefore subject to errors. The performance degradation these errors impose on linear detectors, especially the decorrelating detector, is the topic of this paper.

  • 46. Raya, M.
    et al.
    Papadimitratos, Panagiotis
    Aad, I.
    Jungels, D.
    Hubaux, J. -P
    Eviction of Misbehaving and Faulty Nodes in Vehicular Networks2007In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 25, no 8, p. 1557-1568Article in journal (Refereed)
  • 47.
    Salimi, Somayeh
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Golić, Jovan Dj.
    Salmasizadeh, Mahmoud
    Aref, Mohammad Reza
    Key agreement over a generalized multiple access channel using noiseless and noisy feedback2013In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 31, no 9, p. 1765-1778Article in journal (Refereed)
    Abstract [en]

    A secret key agreement framework involving three users is considered in which each of the users 1 and 2 intends to share a secret key with user 3 and users 1 and 2 are eavesdroppers with respect to each other. There is a generalized discrete memoryless multiple access channel (GDMMAC) from users 1 and 2 to user 3 where the three users receive outputs from the channel. Furthermore, there is a feedback channel from user 3 to users 1 and 2 through which user 3 sends information extracted from the received output from the GDMMAC to increase the key rates. We consider both noiseless and noisy feedback. In the case of noiseless feedback, a public channel of unlimited capacity from user 3 to users 1 and 2 is used only once. In the case of noisy feedback, a noisy broadcast channel (BC) from user 3 to users 1 and 2 can be repeatedly used, like GDMMAC. In both setups, inner bounds of the secret key capacity region are derived. The secret key capacity region is derived in some special cases where the channel inputs and outputs form Markov chains in certain orders. For illustration, the corresponding results are also derived and discussed for Gaussian channels. The cases with noiseless feedback, noisy feedback, and no feedback at all are compared with each other.

  • 48.
    Schiessl, Sebastian
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Gross, James
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Caire, Giuseppe
    Delay Performance of the Multiuser MISO Downlink Under Imperfect CSI and Finite-Length Coding2019In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 37, no 4, p. 765-779Article in journal (Refereed)
    Abstract [en]

    We use stochastic network calculus to investigate the delay performance of a multiuser MISO system with zero-forcing beamforming. First, we consider ideal assumptions with long codewords and perfect CSI at the transmitter, where we observe a strong channel hardening effect that results in very high reliability with respect to the maximum delay of the application. We then study the system under more realistic assumptions with imperfect CSI and finite blocklength channel coding. These effects lead to interference and to transmission errors, and we derive closed-form approximations for the resulting error probability. Compared to the ideal case, imperfect CSI and finite length coding cause massive degradations in the average transmission rate. Surprisingly, the system nevertheless maintains the same qualitative behavior as in the ideal case: as long as the average transmission rate is higher than the arrival rate, the system can still achieve very high reliability with respect to the maximum delay.

  • 49.
    Shi, Guodong
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    The role of persistent graphs in the agreement seeking of social networks2013In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 31, no 9, p. 595-606Article in journal (Refereed)
    Abstract [en]

    This paper investigates the role persistent relations play for a social network to reach a global belief agreement under discrete-time or continuous-time evolution. Each directed arc in the underlying communication graph is assumed to be associated with a time-dependent weight function, which describes the strength of the information flow from one node to another. An arc is said to be persistent if its weight function has infinite L1 or l1 norm for continuous or discrete belief evolutions, respectively. The graph that consists of all persistent arcs is called the persistent graph of the underlying network. Three necessary and sufficient conditions on agreement or ε-agreement are established. We prove that the persistent graph fully determines the convergence to a common opinion in a social network. It is shown how the convergence rate explicitly depends on the diameter of the persistent graph. For a social networking service like Facebook, our results indicate how permanent friendships need to be and what network topology they should form for the network to be an efficient platform for opinion diffusion.

  • 50.
    Shi, Guodong
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Mikael
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    How agreement and disagreement evolve over random dynamic networks2013In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 31, no 6, p. 1061-1071Article in journal (Refereed)
    Abstract [en]

    The dynamics of an agreement protocol interacting with a disagreement process over a common random network is considered. The model can represent the spreading of true and false information over a communication network, the propagation of faults in a large-scale control system, or the development of trust and mistrust in a society. At each time instance and with a given probability, a pair of network nodes interact. At random each of the nodes then updates its state towards the state of the other node (attraction), away from the other node (repulsion), or sticks to its current state (neglect). Agreement convergence and disagreement divergence results are obtained for various strengths of the updates for both symmetric and asymmetric update rules. Impossibility theorems show that a specific level of attraction is required for almost sure asymptotic agreement and a specific level of repulsion is required for almost sure asymptotic disagreement. A series of sufficient and/or necessary conditions are then established for agreement convergence or disagreement divergence. In particular, under symmetric updates, a critical convergence measure in the attraction and repulsion update strength is found, in the sense that the asymptotic property of the network state evolution transits from agreement convergence to disagreement divergence when this measure goes from negative to positive. The result can be interpreted as a tight bound on how much bad action needs to be injected in a dynamic network in order to consistently steer its overall behavior away from consensus.

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