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  • 1. Amat, Alexandre Graell I.
    et al.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory.
    An Introduction to Distributed Channel Coding2014In: Channel coding: theory, algorithms, and applications, SAN DIEGO: ELSEVIER ACADEMIC PRESS INC , 2014, p. 399-450Chapter in book (Refereed)
  • 2.
    Andersson, Mattias
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Rathi, Vishwambhar
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Kliewer, Joerg
    Klipsch School of Electrical and Computer Engineering New Mexico State University.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Equivocation of Eve using two edge type LDPC codes for the binary erasure wiretap channel2010In: 2010 Conference Record of the Forty Fourth Asilomar Conference on Signals, Systems and Computers (ASILOMAR), 2010, p. 2045-2049Conference paper (Refereed)
    Abstract [en]

    We consider transmission over a binary erasure wiretap channel using the code construction method introduced by Rathi et al. based on two edge type Low-Density Parity-Check (LDPC) codes and the coset encoding scheme. By generalizing the method of computing conditional entropy for standard LDPC ensembles introduced by Méasson, Montanari, and Urbanke to two edge type LDPC ensembles, we show how the equivocation for the wiretapper can be computed. We find that relatively simple constructions give very good secrecy performance and are close to the secrecy capacity.

  • 3.
    Andersson, Mattias
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Rathi, Vishwambhar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Kliewer, Jorg
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Nested Polar Codes for Wiretap and Relay Channels2010In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 14, no 8, p. 752-754Article in journal (Refereed)
    Abstract [en]

    We show that polar codes asymptotically achieve the whole capacity-equivocation region for the wiretap channel when the wiretapper's channel is degraded with respect to the main channel, and the weak secrecy notion is used. Our coding scheme also achieves the capacity of the physically degraded receiver-orthogonal relay channel. We show simulation results for moderate block length for the binary erasure wiretap channel, comparing polar codes and two edge type LDPC codes.

  • 4.
    Blasco-Serrano, Ricardo
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Lv, Jing
    Dresden University of Technology.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Jorswieck, Eduard
    Dresden University of Technology.
    Kliks, Adrian
    Poznan University of Technology.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Comparison of Underlay and Overlay Spectrum Sharing Strategies in MISO Cognitive Channels2012In: 2012 7th International ICST Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM), IEEE Computer Society, 2012, p. 224-229Conference paper (Refereed)
    Abstract [en]

    We consider an extension of the cognitive radio channel model in which the secondary transmitter has to obtain (“learn”) the primary message in a first phase rather than having non-causal knowledge of it. We propose an achievable rate region that combines elements of decode-and-forward relaying with coding for the pure cognitive radio channel model. Moreover, we find the choice of parameters that maximize the secondary rate under a primary rate constraint. Finally, we compare numerically the performance of our system to that of an underlay scheme that combines beamforming, rate splitting, and successive decoding. We observe that although the overlay design provides higher rates, the losses due to the first phase are quite severe. In fact, for the considered scenarios, cleverly designed underlay schemes can provide comparable performance.

  • 5.
    Blasco-Serrano, Ricardo
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Lv, Jing
    Dresden University of Technology.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Jorswieck, Eduard
    Dresden University of Technology.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Multi-antenna transmission for underlay and overlay cognitive radio with explicit message-learning phase2013In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499Article in journal (Refereed)
  • 6.
    Blasco-Serrano, Ricardo
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Andersson, Mattias
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Rathi, Vishwambhar
    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 Codes for Cooperative Relaying2012In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 60, no 11, p. 3263-3273Article in journal (Refereed)
    Abstract [en]

    We consider the symmetric discrete memoryless relay channel with orthogonal receiver components and show that polar codes are suitable for decode-and-forward and compress-and-forward relaying. In the first case we prove that polar codes are capacity achieving for the physically degraded relay channel; for stochastically degraded relay channels our construction provides an achievable rate. In the second case we construct sequences of polar codes that achieve the compress-and-forward rate by nesting polar codes for source compression into polar codes for channel coding. In both cases our constructions inherit most of the properties of polar codes. In particular, the encoding and decoding algorithms and the bound on the block error probability O(2 (N beta)) which holds for any 0 < beta < 1/2.

  • 7.
    Blasco-Serrano, Ricardo
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Rathi, Vishwambhar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Polar codes for compress-and-forward in binary relay channels2010In: 44th Asilomar Conference on Signals, Systems and Computers, Asilomar 2010, IEEE conference proceedings, 2010, p. 1743-1747Conference paper (Refereed)
    Abstract [en]

    We construct polar codes for binary relay channels with orthogonal receiver components. We show that polar codes achieve the cut-set bound when the channels are symmetric and the relay-destination link supports compress-and-forward relaying based on Slepian-Wolf coding. More generally, we show that a particular version of the compress-and-forward rate is achievable using polar codes for Wyner-Ziv coding. In both cases the block error probability can be bounded as O(2-Nβ) for 0 < β < 1/2 and sufficiently large block length N.

  • 8.
    Blasco-Serrano, Ricardo
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Bandwidth efficient compress-and-forward relaying based on joint source-channel coding2011In: 2011 IEEE Wireless Communications and Networking Conference, WCNC 2011, IEEE conference proceedings, 2011, p. 1800-1804Conference paper (Refereed)
    Abstract [en]

    We propose a new code design for compress-and-forward relaying over bandlimited relay-to-destination channels. The main contribution of this paper is a code design based on joint (source-channel) coding and modulation that uses the correlation between the observations at the relay and the destination as protection against channel errors. This allows for relay nodes with reduced complexity, shifting most of the processing requirements to the destination node. Moreover, by using scalar quantizers with an entropy constraint our system provides remarkable performance in channel conditions where neither amplify-and-forward nor compress-and-forward efficiently exploit the presence of a relay node. Simulation results confirm the benefits of our proposed system.

  • 9.
    Blasco-Serrano, Ricardo
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    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.
    Communication and interference coordination2014In: 2014 Information Theory and Applications Workshop, ITA 2014 - Conference Proceedings, IEEE conference proceedings, 2014, p. 6804218-Conference paper (Refereed)
    Abstract [en]

    We study the problem of controlling the interference created to an external observer by a communication processes. We model the interference in terms of its type (empirical distribution), and we analyze the consequences of placing constraints on the admissible type. Considering a single interfering link, we characterize the communication-interference capacity region. Then, we look at a scenario where the interference is jointly created by two users allowed to coordinate their actions prior to transmission. In this case, the tradeoff involves communication and interference as well as coordination. We establish an achievable communication-interference region and show that efficiency is significantly improved by coordination.

  • 10.
    Blasco-Serrano, Ricardo
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    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.
    Compress-and-forward relaying based on symbol-wise joint source-channel coding2010In: IEEE International Conference on Communications, IEEE conference proceedings, 2010, p. 1-5Conference paper (Refereed)
    Abstract [en]

    We propose a new compress-and-forward implementation for the relay channel based on joint source-channel coding techniques. The relay performs scalar quantization of its observation in combination with a redundant index mapping. Our system utilizes the correlation between the quantized signal and the direct-link observation of the transmitted symbols as redundancy for error protection on the relay-to-destination link. In order to fully exploit this correlation the destination requires iterative decoding to recover the quantized observation sent by the relay. Once regenerated, this quantized signal is optimally combined with the direct-link observation to decode the message conveyed by the source. By quantizing the observed signal itself rather than a measure on the reliability of the information bits (e.g. a posteriori probabilities from a decoder), and by using digital communication methods on the relay-to-destination link our system yields superior performance to that of amplify-and-forward, decode-and-forward and previous implementations of compress-and-forward based on soft decoding.

  • 11.
    Blasco-Serrano, Ricardo
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    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 Codes for Coordination in Cascade Networks2012In: International Zurich Seminar on Communications: February 29-March 2, 2012, Sorell Hotel Zürichberg, Zurich, Switzerland proceedings, Zürich: Eidgenössische Technische Hochschule Zürich , 2012, p. 55-58Conference paper (Refereed)
    Abstract [en]

    We consider coordination in cascade networks and construct sequences of polar codes that achieve any point in a special region of the empirical coordination capacity region. Our design combines elements of source coding to generate actions with the desired type with elements of channel coding to minimize the communication rate. Moreover, we bound the probability of malfunction of a polar code for empirical coordination. Possible generalizations and open problems are discussed.

  • 12.
    Blasco-Serrano, Ricardo
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Ericsson Research.
    Zachariah, Dave
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Division of Systems and Control. Division of Systems and Control. Uppsala University.
    Sundman, Dennis
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    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.
    A Measurement Rate-MSE Tradeoff for Compressive Sensing Through Partial Support Recovery2014In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 62, no 18, p. 4643-4658Article in journal (Refereed)
    Abstract [en]

    We study the fundamental relationship between two relevant quantities in compressive sensing: the measurement rate, which characterizes the asymptotic behavior of the dimensions of the measurement matrix in terms of the ratio m/ log n (m being the number of measurements and n the dimension of the sparse signal), and the mean square estimation error. First, we use an information-theoretic approach to derive sufficient conditions on the measurement rate to reliably recover a part of the support set that represents a certain fraction of the total signal power when the sparsity level is fixed. Second, we characterize the mean square error of an estimator that uses partial support set information. Using these two parts, we derive a tradeoff between the measurement rate and the mean square error. This tradeoff is achievable using a two-step approach: first support set recovery, then estimation of the active components. Finally, for both deterministic and random signals, we perform a numerical evaluation to verify the advantages of the methods based on partial support set recovery.

  • 13.
    Blasco-Serrano, Ricardo
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Zachariah, Dave
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Sundman, Dennis
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    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.
    An Achievable Measurement Rate-MSE Tradeoff in Compressive Sensing Through Partial Support Recovery2013In: 2013 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), New York: IEEE , 2013, p. 6426-6430Conference paper (Refereed)
    Abstract [en]

    For compressive sensing, we derive achievable performance guarantees for recovering partial support sets of sparse vectors. The guarantees are determined in terms of the fraction of signal power to be detected and the measurement rate, defined as a relation between the dimensions of the measurement matrix. Based on this result we derive a tradeoff between the measurement rate and the mean square error, and illustrate it by a numerical example.

  • 14. De Nardis, L.
    et al.
    Di Benedetto, M. -G
    Tassetto, D.
    Bovelli, S.
    Akhtar, A.
    Holland, O.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Impact of mobility in cooperative spectrum sensing: Theory vs. simulation2012In: Wireless Communication Systems (ISWCS), 2012 International Symposium on, IEEE , 2012, p. 416-420Conference paper (Refereed)
    Abstract [en]

    This work addresses the problem of cooperative spectrum sensing in cognitive radio networks, focusing on the impact of mobility on performance of cooperative sensing. First, a review of the most recent results on cooperative spectrum sensing is provided, resulting in the identification of measurement correlation and frame error rate in the reporting channel as the main parameters influencing the performance of cooperative sensing schemes. Next, the paper discusses the extension of the analysis to the case of mobile sensors, and determines the set of assumptions made in existing literature when taking into account mobility in sensing. The paper moves then to remove some of such assumptions, by presenting simulation results obtained in presence of realistic models for propagation in the considered area, as well as of a realistic mobility model. A comparison between theoretical derivation and simulation results shows that correlation among measurements taken by different sensors and the selected mobility model may significantly affect the sensing performance.

  • 15.
    Dössel, Leefke
    et al.
    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.
    Thobaben, Ragnar
    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.
    Anytime reliability of systematic LDPC convolutional codes2012In: Communications (ICC), 2012 IEEE International Conference on, IEEE , 2012, p. 2171-2175Conference paper (Refereed)
    Abstract [en]

    We propose a LDPC Convolutional Code ensemble together with an expanding-window message-passing decoder that asymptotically have anytime properties when used for streaming transmission on the binary erasure channel. We show analytically that the decoding erasure probability of these codes decays exponentially over decoding delay and determine the corresponding anytime exponents.

  • 16.
    Forssell, Henrik
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Al-Zubaidy, Hussein
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Gross, James
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    On the Impact of Feature-Based Physical Layer Authentication on Network Delay Performance2017In: Globecom 2017 - 2017 IEEE Global Communications Conference, Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    Feature-based authentication schemes that verify wireless transmitter identities based on physical-layer features allow for fast and efficient authentication with minimal overhead. Hence, they are interesting to consider for safety-critical applications where low latency and high reliability is required. However, as erroneous authentication decisions will introduce delays, we propose to study the impact of feature-based schemes on the system-level performance. In this paper, we therefore study the queuing performance of a line-of-sight wireless link that employs a feature-based authentication scheme based on the complex channel gain. Using stochastic networks calculus, we provide bounds on the delay performance which are validated by numerical simulations. The results show that the delay and authentication performance is highly dependent on the SNR and Rice factor. However, under good channel conditions, a missed-detection rate of 10(-8) can be achieved without introducing excessive delays in the system.

  • 17.
    Forssell, Henrik
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Gross, James
    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.
    Feature-Based Multi-User Authentication for Parallel Uplink Transmissions2016In: 2016 9TH INTERNATIONAL SYMPOSIUM ON TURBO CODES AND ITERATIVE INFORMATION PROCESSING (ISTC), IEEE, 2016, p. 355-359Conference paper (Refereed)
    Abstract [en]

    We study a multi-user up-link scenario where an attacker tries to impersonate the legitimate transmitters. We present a new framework for deriving a posteriori attack probabilities from the channel observations at the access point, which enables fast intrusion detection and authentication at the physical layer and can be exploited to reduce the security overhead by offtoading higher-layer authentication schemes. This is highly relevant for delay-sensitive applications that are targeted in 5G where the security overhead may limit the real-time performance. We take a factor-graph approach that can easily be extended to take into account other features, channel models, and radio access schemes. While related works only consider single-link scenarios, the multi-user approach in this paper allows us to exploit the cross-channel correlation of the large-scale fading parameters that is due to the propagation environment for improving the detection performance. As numerical results show, especially for slowly changing channels with high correlation our approach provides significant performance gains.

  • 18. Fouillot, P.
    et al.
    Le Martret, C. J.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Adaptive relaying strategies for collaborative spectrum sensing2010In: 2010 Proceedings of the 5th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, CROWNCom 2010, 2010, p. 5577676-Conference paper (Refereed)
  • 19.
    Gabry, Frederic
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Outage Performance and Power Allocation for Decode-and-Forward Relaying and Cooperative Jamming for the Wiretap Channel2011In: 2011 IEEE International Conference on Communications Workshops, ICC 2011 Workshops, IEEE , 2011Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the wiretap channel in the presence of a cooperative helping node. We derive a closed-form expression for the secrecy outage probability for the decode-and-forward (DF) relaying and cooperative jamming (CJ) strategies for the Rayleigh slow fading channel. We investigate the power allocation at the source and helping node, and compare the secrecy outage performance of the two schemes.

  • 20.
    Gabry, Frederic
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    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.
    Cooperation for secrecy in presence of an active eavesdropper: A game-theoretic analysis2011In: 8th International Symposium on Wireless Communication Systems (ISWCS), 2011, 2011, p. 281-285Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate a four single-antenna node network, constituted of a transmitter, a receiver, a cooperative node and a wiretapper. The wiretapper has the ability to eavesdrop the communication or disrupt the transmission by jamming. This results in both cases in the decrease of the secrecy rate. The cooperative node on the other hand aims to improve secrecy by either relaying or jamming. We investigate the secrecy performance of the decode-and-forward and cooperative jamming strategies against this kind of adversary. To model the interaction between the helper and the wiretapper, we define an extensive form game, for which we derive the pure and mixed strategies equilibria. Finally, we compare the performance of the schemes and we analyze the equilibrium outcomes through simulation results.

  • 21.
    Gabry, Frederic
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Thobaben, Ragnar
    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.
    Outage Performances for Amplify-and-Forward, Decode-and-Forward and Cooperative Jamming Strategies for the Wiretap Channel2011In: 2011 IEEE Wireless Communications and Networking Conference, WCNC 2011, IEEE , 2011, p. 1328-1333Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the wiretap channel in the presence of a cooperative relay node. We analyze and compare the outage performance of three cooperatives schemes: cooperative jamming (CJ), decode-and-forward (DF), and amplify-and-forward (AF) for the Rayleigh slow fading channel. In particular, we derive a closed-form expression for the outage probability for the DF and CJ strategies, which allows an optimal strategy selection in terms of outage performance. We compare the three cooperative schemes through numerical simulations.

  • 22. Gabry, Frederic
    et al.
    Thobaben, Ragnar
    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.
    Secrecy Games In Cognitive Radio Networks with Multiple Secondary Users2015In: 2015 IEEE CONFERENCE ON COMMUNICATIONS AND NETWORK SECURITY (CNS), 2015, p. 143-148, article id 7346822Conference paper (Refereed)
    Abstract [en]

    In this paper we investigate secrecy games in cognitive radio networks with multiple secondary pairs and secrecy constraints. We consider the cognitive channel model with multiple secondary pairs where the secondary receivers are treated as eavesdroppers with respect to the primary transmission. For this novel network model, we derive achievable rate regions when secondary pairs are allowed to use the channel simultaneously. We then investigate the spectrum sharing mechanisms using several game theoretic models, namely 1) a single-leader multiple-follower Stackelberg game with the primary transmitter as the leader and the secondary transmitters as followers; 2) a non-cooperative power control game between the secondary transmitters if they can access the channel simultaneously; and 3) an auction between a primary auctioneer and secondary bidders which allows the primary transmitter to exploit the competitive interaction between the secondary transmitters. We illustrate through numerical simulations the equilibrium outcomes of the analyzed games and the impact of the competition between the secondary transmitters on the utility performance of every node in the cognitive radio network.

  • 23.
    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 Electrical Engineering (EES), Communication Theory. 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.
    Karipidis, Eleftherios
    Thobaben, Ragnar
    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.
    Larsson, Erik G.
    Skoglund, Mikeal
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Secure Broadcasting in Cooperative Cognitive Radio Networks2012In: 2012 Future Network and Mobile Summit, FutureNetw 2012, IIMC , 2012Conference paper (Refereed)
    Abstract [en]

    This paper explores the trade-off between cooperation and secrecy in cognitive radio networks. We consider a scenario consisting of a primary and a secondary system. In the simplest case, each system is represented by a pair of transmitter and receiver. We assume a secrecy constraint on the transmission in the sense that the message of the primary transmitter has to be concealed from the secondary user. Both situations where the secondary transmitter is aware and unaware of the primary message are investigated and compared. Furthermore, we extend our results to the scenario where the secondary system comprises multiple users. For each case we sketch the derivation of the rates that are achievable from an information theoretic perspective. We then investigate the findings by numerical simulations. Our main result is that, in spite of the secrecy constraint, cooperation is beneficial in terms of the achievable rates. The secondary transmitter has the two contradicting tasks of helping the primary system and transmitting its own message. Our results show that both tasks can be accomplished simultaneously, improving both systems' performance. In particular, the secondary system can achieve a significant rate without decreasing the primary rate below the benchmark rate achievable without the help of the secondary transmitter. In the case of multiple secondary users, the rate region reduces, which results in a lower individual rate. However, the linear increase in sumrate counterbalances this effect.

  • 24.
    Gabry, Frédéric
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Salimi, Somayen
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    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.
    High SNR performance of amplify-and-forward relaying in Rayleigh fading wiretap channels2013In: 2013 Iran Workshop on Communication and Information Theory, IWCIT 2013, IEEE , 2013, p. 6555771-Conference paper (Refereed)
    Abstract [en]

    This paper investigates amplify-and-forward (AF) relaying for secrecy in quasi-static Rayleigh fading channels. We consider a four-node network where a helping node intends to enhance secrecy of the transmission between the source and the destination in presence of a passive eavesdropper. In this scenario, the common assumption of full CSI on the eavesdropper's channels is not realistic, and thus, we study the performance of cooperation from an outage perspective. Starting from the secrecy outage probability, we introduce a novel measure, the conditional secrecy outage probability to analyze the performance of AF. In particular, we derive closed-form expressions for AF for these two secrecy measures under a high SNR assumption. Moreover, we use numerical examples to illustrate our results and to characterize the effect of the nodes' geometry. We also show numerically how AF improves the secrecy performance in comparison to direct transmission in terms of outage probability and secure throughput.

  • 25.
    Gabry, Frédéric
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. 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.
    Li, Nan
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    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.
    Cooperation for Secure Broadcasting in Cognitive Radio Networks2012In: Communications (ICC), 2012 IEEE International Conference on, IEEE , 2012, p. 5613-5618Conference paper (Refereed)
    Abstract [en]

    This paper explores the trade-off between cooperation and secrecy in cognitive radio networks. We consider a scenario consisting of a primary and a secondary system. In the simplest case, each system is represented by a pair of transmitter and receiver. We assume a secrecy constraint on the transmission in the sense that the message of the primary transmitter has to be concealed from the secondary receiver. Both situations where the secondary transmitter is aware and unaware of the primary message are investigated and compared. In the first case, the secondary transmitter helps by allocating power for jamming, which increases the secrecy of the first message. In the latter case, it can also act as a relay for the primary message, thus improving the reliability of the primary transmission. Furthermore, we extend our results to the scenario where the secondary system comprises multiple receivers. For each case we present achievable rate regions. We then provide numerical illustrations for these rate regions. Our main result is that, in spite of the secrecy constraint, cooperation is beneficial in terms of the achievable rates. In particular, the secondary system can achieve a significant rate without decreasing the primary rate below the benchmark rate achievable without the help of the secondary transmitter. Finally, we investigate the influence of the distances between users on the system's performance.

  • 26.
    Gabry, Frédéric
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Huawei France Research Center, France.
    Zappone, A.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Jorswieck, E. A.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Energy Efficiency Analysis of Cooperative Jamming in Cognitive Radio Networks with Secrecy Constraints2015In: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 4, no 4, p. 437-440, article id 7106492Article in journal (Refereed)
    Abstract [en]

    We investigate energy-efficient 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 should ensure that the primary message is not leaked to the secondary user by using cooperative jamming. We investigate the optimal power allocation and power splitting at the secondary transmitter for our cognitive model to maximize the secondary energy efficiency (EE) under secrecy constraints. We formulate and analyze an important EE Stackelberg game between the two transmitters aiming at maximizing their utilities. We illustrate the analytical results through our geometrical model, highlighting the EE performance of the system and the impact of the Stackelberg game.

  • 27.
    Grosjean, Leefke
    et al.
    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.
    Thobaben, Ragnar
    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.
    Systematic LDPC Convolutional Codes: Asymptotic and Finite-Length Anytime Properties2014In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, ISSN 0090-6778, Vol. 62, no 12, p. 4165-4183Article in journal (Refereed)
    Abstract [en]

    Here we propose an ensemble of non-terminated systematic LDPC convolutional codes with increasing memory, and show that over the binary erasure channel (BEC) these codes achieve anytime reliability asymptotically when decoded with an expanding-window message-passing decoder. The corresponding anytime exponents are determined through protograph-based extrinsic information transfer charts. Fundamental complications arising when transmitting with finite block lengths are identified and a combinatorial performance analysis, when transmitting over a static BEC with a fixed number of erasures per codeword block, is developed. Based on the performance analysis we explore the use of feedback for achieving anytime behavior with constraints on block length. To meet complexity constraints, with or without feedback, the code memory can be limited at the cost of an error floor emerging with a delay proportional to the memory constraint. Although the analysis is developed for a static BEC we show numerically that we can design efficient low-complexity finite-length codes with anytime properties even for the conventional BEC.

  • 28.
    Grosjean, Leefke
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Rasmussen, Lars K.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Communication Theory.
    Variable-rate anytime transmission with feedback2016In: IEEE Vehicular Technology Conference, IEEE, 2016, article id 7881963Conference paper (Refereed)
    Abstract [en]

    A generalization of the ensemble of non-terminated systematic LDPC convolutional codes developed in our previous work is proposed that allows us to design codes with lower rates than the original structure. We show that over the BEC, the modified codes have improved asymptotic and finite-length behavior and we determine the operational anytime exponent. Having shown the advantages of lowering the rate of the code, we propose a feedback protocol that permits encoder and decoder to operate at a variable rate. The rate is set on-the-fly and depends on the decoding success of the decoder. We describe the construction of the variable rate code structure and demonstrate by simulations the superiority of the variable rate scheme as compared to a scheme using a fixed rate.

  • 29. Kansanen, K.
    et al.
    Kim, A. N.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Karlsson, Johannes
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Low complexity bandwidth compression mappings for sensor networks2010In: Final Program and Abstract Book: 4th International Symposium on Communications, Control and Signal Processing, Limassol, 2010, Vol. ISCCSP 2010Conference paper (Refereed)
    Abstract [en]

    Compressive (2:1) joint source-channel coding using direct mappings from source to channel symbol space is considered. To enable the use of prior information due to e.g. correlated samples at the receiver, or statistical knowledge of the source, minimum mean square error decoding is considered. The prior information is incorporated in the form of the a-priori distribution in the decoding. Four mapping methods are presented and evaluated using the generic Bayesian minimum mean square error estimator. The schemes are evaluated for transmitting a memoryless Gaussian source over additive white Gaussian noise channel with a quadratic distortion measure. The simplicity of implementation and applicability to a wider variety of sources is discussed.

  • 30.
    Kittichokechai, Kittipong
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    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.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Source and channel coding with action-dependent partially known two-sided state information2010In: IEEE International Symposium on Information Theory - Proceedings, 2010, p. 629-633Conference paper (Refereed)
    Abstract [en]

    We consider a source coding problem where the encoder can take actions that influence the availability and/or quality of the side information which is available partially and noncausally at the encoder and the decoder. We then characterize the associated achievable tradeoffs between rate, distortion, and cost. In addition, we state and discuss a capacity result for the channel coding dual problem where the formula duality of special cases is recognized.

  • 31.
    Kliewer, J.
    et al.
    University of Kiel.
    Thobaben, Ragnar
    University of Kiel.
    Combining FEC and optimal soft-input source decoding for the reliable transmission of correlated variable-length encoded signals2002In: DATA COMPRESSION CONFERENCE, PROCEEDINGS, 2002, p. 83-91Conference paper (Refereed)
    Abstract [en]

    In this paper we utilize both the implicit residual source correlation and the explicit redundancy from a forward-error-correction (FEC) scheme for the error protection of packetized variable-length encoded source indices. The implicit source correlation is exploited in a novel symbol-based soft-input a-posteriori probability (APP) decoder, which leads to an optimal decoding process in combination with a mean-squares or maximum a-posteriori probability estimation of the reconstructed source signal. When additionally the variable-length encoded source data is protected by channel codes, an iterative source-channel decoder can be obtained in the same way as for serially concatenated codes, where the outer constituent decoder is replaced by the proposed APP source decoder. Simulation results show that by additionally considering the correlations between the variable-length encoded source indices the error-correction performance can be highly increased.

  • 32.
    Kliewer, J.
    et al.
    University of Kiel.
    Thobaben, Ragnar
    University of Kiel.
    Iterative joint source-channel decoding of variable-length codes using residual source redundancy2005In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 4, no 3, p. 919-929Article in journal (Refereed)
    Abstract [en]

    We present a novel symbol-based soft-input a posteriori probability (APP) decoder for packetized variable-length encoded source indexes transmitted over wireless channels where the residual redundancy after source encoding is exploited for error protection. In combination with a mean-square or maximum APP estimation of the reconstructed source data, the whole decoding process is close to optimal. Furthermore, solutions for the proposed APP decoder with reduced complexity are discussed and compared to the near-optimal solution. When, in addition, channel codes are employed for protecting the variable-length encoded data, an iterative source-channel decoder can be obtained in the same way as for serially concatenated codes, where the proposed APP source decoder then represents one of the two constituent decoders. The simulation results show that this iterative decoding technique leads to substantial error protection for variable-length encoded correlated source signals, especially, when they are transmitted over highly corrupted channels.

  • 33.
    Kliewer, J
    et al.
    University of Kiel.
    Thobaben, Ragnar
    University of Kiel.
    On the utilization of residual source redundancy for iterative joint source-channel decoding of variable-length codes2002In: ISIT: 2002 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY, PROCEEDINGS, NEW YORK: IEEE , 2002, p. 199-199Conference paper (Refereed)
    Abstract [en]

    We present a novel symbol-based a-posteriori probability (APP) decoder for packetized variable-length encoded source indices transmitted over wireless channels, which exploits residual index correlations after source encoding for error correction. By additionally protecting the variable-length encoded bitstream with channel codes, an iterative decoding scheme can be obtained where the proposed APP source decoder serves as constituent decoder.

  • 34.
    Kliewer, J.
    et al.
    University of Kiel.
    Thobaben, Ragnar
    University of Kiel.
    Parallel concatenated joint source-channel coding2003In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 39, no 23, p. 1664-1666Article in journal (Refereed)
    Abstract [en]

    A novel approach for robust source transmission where variable-length source and channel encoding are concatenated in parallel is presented. Simulation results show that for waveform source signals the proposed scheme shows a strong increase in decoding performance compared to the typically applied serially concatenated scheme.

  • 35.
    Kliewer, Jörg
    et al.
    University of Kiel.
    Thobaben, Ragnar
    University of Kiel.
    A-posteriori probability decoding of variable-length codes using a three-dimensional trellis representation2003In: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, 2003, p. 2213-2217Conference paper (Refereed)
    Abstract [en]

    In this contribution we present an improved index-based a-posteriori probability (APP) decoding approach for variable-length encoded packetized data, where implicit residual source correlation is exploited for error protection. The proposed algorithm is based on a novel generalized two-dimensional state representation which leads to a three-dimensional trellis with unique state transitions. APP decoding on this trellis is realized by employing a two-dimensional version of the classical BCJR algorithm. This new method has the advantage that due to the unique state representation all available a-priori information can be fully exploited, which especially holds for the transition probabilities of the Markov model associated with the variable-length encoded source indices. Simulation results for an additional error protection by channel codes and iterative joint source-channel decoding show that the proposed approach leads to an increased error-correction performance compared to previously published results where a one-dimensional state representation is used.

  • 36.
    Kliks, Adrian
    et al.
    Poznan University of Technology.
    Sroka, Pawel
    Poznan University of Technology.
    Lv, Jing
    Dresden University of Technology.
    Jorswieck, Eduard
    Dresden University of Technology.
    Blasco-Serrano, Ricardo
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Crystallized Rate Regions in the Secondary Interference Channels2012In: 2012 International ITG Workshop on Smart Antennas (WSA), IEEE conference proceedings, 2012, p. 312-317Conference paper (Refereed)
    Abstract [en]

    In this paper the problem of sum-rate maximization for secondary cognitive users (SU) in presence of a primary user (PU) transmission is considered. We assume that all of the users are equipped with multiple transmit/receive antennas and that the cognitive users must not induce more interference to the primary users than it is defined in the permissive policy and expressed in terms of a spectrum mask or interference temperature constraint. We employ game-theory to find the so-called correlated equilibrium that corresponds to the playing strategy definitions for all users. Actually, the Vickrey-Clarke-Groves theory has been applied and the regret-matching algorithm has been implemented to find the optimal playing strategy for both secondary users. New cost function has been proposed that allows for fast convergence of the developed solutions to the optimal or sub-optimal point. Extensive simulation results have been carried out to corroborate the correctness of the proposed approach.

  • 37. Larsson, E. G.
    et al.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Wang, G.
    On diversity combining with unknown channel state information and unknown noise variance2010In: IEEE Wireless Communications and Networking Conference, 2010, Vol. WCNCConference paper (Refereed)
    Abstract [en]

    We derive detection metrics for soft-output diversity combining for the case of imperfect channel state information at the receiver. We treat in particular the case when the noise variance at the receiver is unknown. We contrast conventional training-based methods to a detector based on the generalized likelihood-ratio (GLR) test paradigm. We study the performance of the detectors via EXIT chart analysis and via simulations of LDPC coded transmission over a fast Rayleigh fading channel. The results show that the GLR receivers can significantly outperform the conventional detectors. ᅵ2010 IEEE.

  • 38. Lin, P. -H
    et al.
    Gabry, F.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Jorswieck, E.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Interference neutralization vs clean relaying in cognitive radio networks with secrecy2015In: Proceedings of the 12th International Conference on Mobile and Ubiquitous Systems: Computing, Networking and Services, MOBIQUITOUS 2015, IEEE conference proceedings, 2015, p. 240-246Conference paper (Refereed)
    Abstract [en]

    In this paper we study cognitive radio networks with secrecy constraints on the primary transmission. In particular we consider several transmission schemes for the secondary transmitter, namely interference neutralization (IN) and cooperative jamming with and without clean relaying (CR). We derive and analyze the achievable secondary rate performance of the schemes. Furthermore we thoroughly investigate the advantages and shortcomings of these schemes through numerical simulations in a geometric model where we highlight the impact of the users' locations and show the important difference in all schemes depending on the topology. Our results show that the secondary transmitter can successfully adapt its transmission scheme (and parameters), i.e., either IN or CR, depending on its location to maximize its rate while insuring perfect secrecy of the primary transmission.

  • 39. Lin, P. -H
    et al.
    Gabry, F.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Jorswieck, E.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Multi-phase transmission for secure cognitive radio networks2015In: 2015 IEEE International Conference on Communication Workshop, ICCW 2015, IEEE conference proceedings, 2015, p. 475-479Conference paper (Refereed)
    Abstract [en]

    In this paper we study secure communications with weak secrecy constraint in a cognitive radio channel, where the secondary receiver is treated as a potential eavesdropper with respect to the primary transmission. The primary's secrecy rate and the transmission scheme should be kept unchanged whether the secondary users transmit or not. We derive the achievable rate of the discrete memoryless multi-phase cognitive channel. To against the information leakage due to the use of Gelfand-Pinsker coding at the secondary transmitter, we derive the corresponding constraints to guarantee the primary's secure transmission. We then specialize the results to the additive white Gaussian noise channels. Numerical results show the advantages of using the proposed multiple-phase transmission scheme over the traditional ones without the additional phase.

  • 40. Lin, P. -H
    et al.
    Gabry, Frédéric
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Jorswieck, E.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Clean relaying in cognitive radio networks with variational distance secrecy constraint2014In: 2014 IEEE Globecom Workshops, GC Wkshps 2014, 2014, p. 1337-1342Conference paper (Refereed)
    Abstract [en]

    In this paper we investigate the cooperative secure communication in a four-node cognitive channel where the secondary receiver is treated as a potential eavesdropper with respect to the primary transmission with variational distance constraint. And the primary user's secrecy rate is required to be unchanged. We propose the clean relaying with the cooperative jamming scheme to achieve this goal, where the secondary transmitter splits its transmitting phase into two non-overlapped intervals after successfully decoding the primary message. Due to the considered secrecy metric, we resort to the information spectrum method, to derive the achievable secrecy rates for the primary user. Then we formulate the secondary user's rate maximization problem over the power allocation and time splitting at the cognitive transmitter under the constraint that primary user's secrecy rate is unchanged. Numerical results show that the secondary transmitter can choose clean relaying or pure cooperative jamming according to the relative positions of the nodes to achieve better performance than the one without any clean phase.

  • 41.
    Lv, Jing
    et al.
    Dresden University of Technology.
    Blasco-Serrano, Ricardo
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Jorswieck, Eduard
    Dresden University of Technology.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Linear Precoding in MISO Cognitive Channels with Causal Primary Message2012In: 2012 International Symposium on Wireless Communication Systems (ISWCS), IEEE conference proceedings, 2012, p. 406-410Conference paper (Refereed)
    Abstract [en]

    The coexistence of a single-input single-output (SISO) primary link and a multiple-input single-output (MISO) secondary link is considered in an extended cognitive radio channel setup, where the secondary transmitter has to obtain (“learn”) the primary message in a first phase rather than having non-causal knowledge of it. An achievable rate region is derived that combines decode-and-forward relaying with linear precoding in the second phase. The optimal transmission strategy is found that maximizes the secondary rate with the primary rate requirement. The performance of the proposed strategy is compared with that in [1], where dirty-paper coding (DPC) is deployed in the second phase, in terms of average secondary rate. The performance degradation is negligible at certain SNR and primary link load, and the implementation is of lower complexity. The comparison with the underlay strategy in [2] is also performed, where the secondary transmitter has no knowledge of the primary message.

  • 42.
    Lv, Jing
    et al.
    Dresden University of Technology.
    Blasco-Serrano, Ricardo
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Jorswieck, Eduard
    Dresden University of Technology.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Kliks, Adrian
    Poznan University of Technology.
    Optimal beamforming in MISO cognitive channels with degraded message sets2012In: Wireless Communications and Networking Conference (WCNC), 2012 IEEE, IEEE Communications Society, 2012, p. 538-543Conference paper (Refereed)
    Abstract [en]

    In this paper we consider the coexistence of a single-input single-output (SISO) primary link with a multiple-input single-output (MISO) secondary user pair that has non-causal knowledge of the primary message. We study an achievable rate region that exploits this knowledge by combining selfless relaying to maintain the rate supported by the primary link with dirty paper coding to pre-cancel the interference at the secondary receiver. We find the optimal choice of power allocation between these operating modes at the secondary transmitter as well as the optimal beamforming vectors. Moreover, we address the robustness of the solution to uncertainties in the channel knowledge. Finally, we show by numerical evaluation the gains obtained due to the additional knowledge of the primary message.

  • 43.
    Lv, Jing
    et al.
    Dresden University of Technology.
    Jorswieck, Eduard
    Dresden University of Technology.
    Blasco-Serrano, Ricardo
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Kliks, Adrian
    Poznan University of Technology.
    Linear precoding in MISO cognitive channels with degraded message sets2012In: 2012 International ITG Workshop onSmart Antennas (WSA), IEEE conference proceedings, 2012, p. 119-124Conference paper (Refereed)
    Abstract [en]

    In this work, the coexistence of a single-input single-output (SISO) primary link and a multiple-input single-output (MISO) secondary link is considered, where the secondary transmitter has non-causal knowledge of primary message and transmits both primary and secondary messages. The optimal beamforming vectors and power allocation at the secondary transmitter are derived to maximize the achievable secondary rate while satisfying the primary rate requirement. Moreover, the optimal linear precoding is obtained by semidefinite relaxation and rank-one decomposition, when the number of antennas at the secondary transmitter is larger than two. Finally, the performance of the proposed scheme is evaluated through numerical simulations.

  • 44.
    Mietzner, Jan
    et al.
    University of Kiel.
    Thobaben, Ragnar
    University of Kiel.
    Hoeher, Peter Adam
    University of Kiel.
    Analysis of the expected error performance of cooperative wireless networks employing distributed space-time codes2004In: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, 2004, p. 2854-2858Conference paper (Refereed)
    Abstract [en]

    In this paper, typical uplink scenarios in a cellular system are considered, where two cooperating mobile stations (serving, for example, as mobile relays) are transmitting the same information to a base station by using a distributed space-time coding scheme. Due to the distributed nature of the system, the transmitted signals are typically subject to different average path losses. For fixed distances between the mobile stations and the base station, the error performance of the distributed space-time coding scheme is determined analytically. Then, based on considerations concerning the spatial distribution of the mobile stations, analytical expressions for the distribution of the average path losses are derived and verified by means of simulations. These results are then used in order to compute the expected error performance of the system. It is shown that in most scenarios the average performance loss compared to a conventional multiple-antenna system with colocated antennas is less than 2 dB at a bit error rate of 10(-3). The most significant performance losses occur for a large path-loss exponent.

  • 45.
    Mouris, Boules Atef
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Quevedo-Teruel, Oscar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Exploiting Glide Symmetry in Planar EBG Structures2018In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 963, no 1, article id 012002Article in journal (Refereed)
    Abstract [en]

    Periodic structures such as electromagnetic band gap (EBG) structures can be used to prevent the propagation of electromagnetic waves within a certain frequency range known as the stop band. One of the main limitations of using EBG structures at low frequencies is their relatively large size. In this paper, we investigate the possibility of using glide symmetry in planar EBG structures to reduce their size. Simulated results demonstrate that exploiting glide symmetry in EBG structures can lead to size reduction.

  • 46.
    Naghibi, Farshad
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Salimi, Somayeh
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    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.
    The Lossless CEO Problem with Security Constraints2013In: Proceedings of the 10th International Symposium on Wireless Communication Systems (ISWCS), VDE Verlag GmbH, 2013, p. -238Conference paper (Refereed)
    Abstract [en]

    In this paper, we investigate the problem of transmitting a remote information source to a single destination via multiple agents in the presence of an eavesdropper. The agents observe noisy versions of the source, then, compress and transmit their observations to the destination via noiseless rate-limited links. The destination should reconstruct the remote source based on the information received from the agents. The eavesdropper, with access to side information correlated with the source, can eavesdrop one of the links from the agents to the destination to obtain as much information as possible about the source. For this problem, we determine the rates at which the agents should transmit such that the destination can recover the source while the equivocation at the eavesdropper node is maximized. We derive inner and outer bounds on the compression-equivocation region. Furthermore, we obtain the compression-equivocation region in special cases where the bounds are tight.

  • 47.
    Naghibi, Farshad
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Salimi, Somayeh
    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.
    Layered LDPC Convolutional Codes for Compression of Correlated Sources under Adversarial Attacks2012In: 2012 International Symposium on Information Theory and Its Applications, ISITA 2012, IEICE , 2012, p. 165-169Conference paper (Refereed)
    Abstract [en]

    We consider the problem of code design for compression of correlated sources under adversarial attacks. A scenario with three correlated sources is considered in which at most one source is compromised by an adversary. The theoretical minimum achievable sum-rate for this scenario was derived by Kosut and Tong. We design layered LDPC convolutional codes for this problem, assuming that one of the sources is available at the common decoder as side information. We demonstrate that layered LDPC convolutional codes constitute a sequence of nested codes where each sub-code is capacity-achieving for the binary symmetric channels used to model the correlation between sources, and therefore, can ideally achieve the theoretical minimum sum-rate. Simulated performance results for moderate block length show a small gap to the theoretical limit, and as the block length increases the gap vanishes.

  • 48.
    Rathi, Vishwambhar
    et al.
    Nvidia Corporation, United States.
    Andersson, Mattias
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Kliewer, Joerg
    Klipsch School of Electrical and Computer Engineering New Mexico State University.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Performance analysis and design of two edge-type LDPC codes for the BEC wiretap channel2013In: IEEE Transactions on Information Theory, ISSN 0018-9448, E-ISSN 1557-9654, Vol. 59, no 2, p. 1048-1064Article in journal (Refereed)
    Abstract [en]

    We consider transmission over a wiretap channel where both the main channel and the wiretapper's channel are binary erasure channels (BEC). A code construction method is proposed using two edge-type low-density parity-check (LDPC) codes based on the coset encoding scheme. Using a single edge-type LDPC ensemble with a given threshold over the BEC, we give a construction for a two edge-type LDPC ensemble with the same threshold. If the given single edge-type LDPC ensemble has degree two variable nodes, our construction gives rise to degree one variable nodes in the code used over the main channel. This results in zero threshold over the main channel. In order to circumvent this problem, the degree distribution of the two edge-type LDPC ensemble is numerically optimized. We find that the resulting ensembles are able to perform close to the boundary of the rate-equivocation region of the wiretap channel. Further, a method to compute the ensemble average equivocation of two edge-type LDPC ensembles is provided by generalizing a recently published approach to measure the equivocation of single edge-type ensembles for transmission over the BEC in the point-to-point setting. From this analysis, we find that relatively simple constructions give very good secrecy performance.

  • 49.
    Rathi, Vishwambhar
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Andersson, Mattias
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragner
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Kliewer, Jörg
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Two edge type LDPC codes for the wiretap channel2009In: Conference Record - Asilomar Conference on Signals, 2009, Vol. Systems and Computers, p. 834-838Conference paper (Refereed)
    Abstract [en]

    We consider transmission over a wiretap channel where both the main channel and the wiretapper's channel are Binary Erasure Channels (BEC). We propose a code construction using two edge type LDPC codes based on the method of Thangaraj, Dihidar, Calderbank, McLaughlin and Merolla. The advantage of our construction is that we can easily calculate the threshold over the main channel. Using standard LDPC codes with a given threshold over the BEC we give a construction for a two edge type LDPC code with the same threshold. Since this construction gives a code for the main channel with threshold zero we also give numerical methods to find two edge type LDPC codes with non-zero threshold for the main channel.

  • 50.
    Sandberg, Henrik
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Dan, György
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Differentially private state estimation in distribution networks with smart meters2015In: Proceedings of the IEEE Conference on Decision and Control, IEEE conference proceedings, 2015, p. 4492-4498Conference paper (Refereed)
    Abstract [en]

    State estimation is routinely being performed in high-voltage power transmission grids in order to assist in operation and to detect faulty equipment. In low- and medium-voltage power distribution grids, on the other hand, few real-time measurements are traditionally available, and operation is often conducted based on predicted and historical data. Today, in many parts of the world, smart meters have been deployed at many customers, and their measurements could in principle be shared with the operators in real time to enable improved state estimation. However, customers may feel reluctance in doing so due to privacy concerns. We therefore propose state estimation schemes for a distribution grid model, which ensure differential privacy to the customers. In particular, the state estimation schemes optimize different performance criteria, and a trade-off between a lower bound on the estimation performance versus the customers' differential privacy is derived. The proposed framework is general enough to be applicable also to other distribution networks, such as water networks.

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