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  • 1.
    al-Askary, Omar
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Ben Slimane, Slimane
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Effect of error in CSI on the capacity of Rayleigh fading channels with QAM signalling and the design of robust signal constellations2007In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 1, no 6, p. 1118-1125Article in journal (Refereed)
    Abstract [en]

    The effects of channel estimation errors on the channel capacity of a discrete time, discrete input, infinite output Rayleigh fading channel are investigated. The case of conventional modulation methods such as phase shift keying (PSK) and quatrature amplitude modulation (QAM) is investigated at first where it was observed that the capacity degrades rapidly with increasing channel estimation errors. The effect of error in the channel estimation is similar to the effect of higher noise in the channel that depends on the transmitted signal. A genetic algorithm is used to optimise the signal constellation in order to maximise the capacity for a given finite number of signal points. The aim of trying to maximise the capacity is to estimate the remaining gap in performance between a traditional modulation scheme such as QAM and the best possible constellation that is optimised for the channel. The constellations obtained from the genetic algorithm are, in general, not directly implementable. A method to design practical robust signal constellations that overcome the effect of channel state information (CSI) error is presented. The robust signal constellations obtained show a performance that is very close to the optimal constellations. In this work, the probability distribution of the error in CSI is assumed to be known.

  • 2.
    Chu, Thi My Chinh
    et al.
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Phan, Hoc
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Delay Analysis for Cognitive Ad Hoc Networks Using Multi-channel Medium Access Control2014In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 8, no 7, p. 1083-1093Article in journal (Refereed)
    Abstract [en]

    In this study, the authors analyse the average end-to-end packet delay for a cognitive ad hoc network where multiple secondary nodes randomly contend for accessing the licensed bands of primary users in non-slotted time mode. Before accessing the licensed bands, each node must perform spectrum sensing and collaboratively exchange the sensing results with other nodes of the corresponding communication as a means of improving the accuracy of spectrum sensing. Furthermore, the medium access control with collision avoidance mechanism based distributed coordination function specified by IEEE802.11 is applied to coordinate spectrum access for this cognitive ad hoc network. To evaluate the system performance, the authors model the considered network as an open G/G/1 queuing network and utilise the method of diffusion approximation to analyse the end-to-end packet delay. The authors’ analysis takes into account not only the number of secondary nodes, the arrival rate of primary users and the arrival rate of secondary users but also the effect of the number of licensed bands when assessing the average end-to-end packet delay of the networks.

  • 3.
    Du, Jinfeng
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Xiao, Pei
    University of Surrey Guildford, UK.
    Wu, Jinsong
    Bell Laboratories, Alcatel-Lucent, Shanghai, China.
    Chen, Qingchun
    Southwest Jiaotong University, Chengdu, China.
    Design of isotropic orthogonal transform algorithm-based multicarrier systems with blind channel estimation2012In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 6, no 16, p. 2695-2704Article in journal (Refereed)
    Abstract [en]

    Orthogonal frequency division multiplexing (OFDM) technique has gained increasing popularity in both wired andwireless communication systems. However, in the conventional OFDM systems the insertion of a cyclic prefix (CP) and the transmission of periodic training sequences for purpose of channel estimation decrease the system’s spectral efficiency. As an alternative to OFDM, isotropic orthogonal transform algorithm (IOTA)-based multicarrier system adopts a proper pulse shaping with good time and frequency localisation properties to avoid interference and maintain orthogonality in real field among sub-carriers without the use of CP. In this study, the authors propose linearly precoded IOTA-based multicarrier systems to achieve blind channel estimation by utilising the structure of auto-correlation and cross-correlation matrices introduced by precoding. The results show that the proposed IOTA-based multicarrier systems achieve better power and spectral efficiency compared with the conventional OFDM systems.

  • 4.
    Ferrer-Coll, Javier
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Ängskog, Per
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Chilo, José
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Stenumgaard, Peter
    FOI, Totalförsvarets forskningsinstitut.
    Characterisation of highly absorbent and highly reflective radio wave propagation environments in industrial applications2012In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 6, no 15, p. 2404-2412Article in journal (Refereed)
    Abstract [en]

    Experience has shown that Bluetooth, Wireless LAN (WLAN), Digital Enhanced Cordless Telecommunications (DECT) and other Industrial, Scientific and Medical (ISM) frequency band wireless technologies developed for office use, have encountered problems when used in critical industrial applications. The development of more reliable wireless solutions requires extensive knowledge of industrial environments with regards to both electromagnetic interference and wave propagation. This study presents the results of the analysis of two important classes of industrial environments having opposite characteristics, one being highly absorbent and the other being highly reflective, with respect to radio wave propagation. The analysis comprises both multipath and path loss characterisation. The results show that wireless solutions with different fundamental properties must be chosen for each of these environments to ensure high reliability. The conclusions of this work can be used as an important reference for further research in this area, as well as the design of new standards and guidelines for selecting wireless solutions in similar industrial environment classes.

  • 5. Lau, Katrina
    et al.
    Goodwin, Graham C.
    Wigren, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Brus, Linda
    Improving the performance of cellular uplinks via power overbooking2017In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 11, no 9, p. 1512-1518Article in journal (Refereed)
  • 6. Li, Jung Shian
    et al.
    Liu, Kun Hsuan
    Chilamkurti, Naveen
    Shu, L.
    Duong, Quang Trung
    Blekinge Institute of Technology, School of Computing.
    Scheduling performance enhancement by network coding in wireless mesh networks2012In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 6, no 13, p. 1912-1919Article in journal (Refereed)
    Abstract [en]

    When a wireless mesh network accommodates interactive applications with quality of service requirements, schedule-based protocols are more suitable than contention-based protocols. In this paper, the problem of determining an appropriate schedule assignment for multiple group transmissions within a spatial time division multiple access link scheduling network is referred to as an integrated multiple-group communication and link scheduling problem. A polynomial-time scheduling algorithm, designated as a source-parallel-aware assignment (SPAA), is proposed to increase the spatial utilisation within each time slot in order to enhance the network throughput. Furthermore, an advanced version of SPAA, designated as joint source-parallel-aware assignment with network coding (JSANC), is proposed to reduce the effects of bottleneck paths on the schedule frame length by flexibly applying conventional or opportunistic network coding approaches. Simulation results show that the proposed algorithms achieve a better network throughput than existing flow-based or particular order-based scheduling schemes.

  • 7.
    Liu, Junnan
    et al.
    Xi An Jiao Tong University, Peoples R China.
    Zhang, Xingjun
    Xi An Jiao Tong University, Peoples R China.
    Blow, Keith
    Aston University, England.
    Fowler, Scott
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Performance analysis of packet layer FEC codes and interleaving in FSO channels2017In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 11, no 13, p. 2042-2048Article in journal (Refereed)
    Abstract [en]

    The combination of forward error correction (FEC) and interleaving can be used to improve free-space optical communication systems. Recent research has optimised the codeword length and interleaving depth under the assumption of a fixed buffering size; however, how the buffering size influences the system performance remains unsolved. This study models the system performance as a function of buffering size and FEC recovery threshold, which allows system designers to determine optimum parameters in consideration of the overhead. The modelling is based on statistics of temporal features of correct data reception and burst error length through the measurement of the channel good time and outage time. The experimental results show good coherence with the theoretical values. This method can also be applied in other channels if a continuous-time-Markov-chain model of the channel can be derived.

  • 8.
    Phan, Hoc
    et al.
    Blekinge Institute of Technology, School of Computing.
    Duong, Trung Q.
    Blekinge Institute of Technology, School of Computing.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, School of Computing.
    Tsiftsis, Theodoros A.
    Distributed orthogonal space–time block coding in wireless relay networks2013In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 7, no 16Article in journal (Refereed)
    Abstract [en]

    In this study, the authors consider distributed orthogonal space–time block coding for relay-based channel state information-assisted amplify-and-forward networks. Specifically, they show that opportunistic relaying (OR) is an optimal solution in terms of instantaneous signal-to-noise ratio (SNR), that is, it provides the maximum instantaneous SNR under the constraint of fixed transmit power for the relays. In particular, instead of allocating the given transmit power to all relays, letting the best relay transmit with this power is an optimal solution for maximising the received SNR. To exhibit this benefit, Monte Carlo simulations are presented showing superior performance of the OR scheme compared to equal power allocation policy for the considered relay networks. For the considered optimal scenario, the authors further derive analytical expressions for the outage probability and symbol error rate (SER) over quasi-static independent, not necessarily identically distributed Nakagami-m fading channels. They further present asymptotically tight approximations for the outage probability and SER in the high SNR regime, rendering insights into the cooperative diversity behaviour. Finally, numerical results are provided to examine the effect of network parameters on the system performance of the considered network.

  • 9.
    Phan, Hoc
    et al.
    Blekinge Institute of Technology, School of Computing.
    Zepernick, Hans-Jürgen
    Blekinge Institute of Technology, School of Computing.
    Tran, Hung
    Blekinge Institute of Technology, School of Computing.
    Impact of interference power constraint on multi-hop cognitive amplify-and-forward relay networks over Nakagami-m fading2013In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 7, no 9, p. 860-866Article in journal (Refereed)
    Abstract [en]

    In this article, the authors study the effect of peak interference power constraint given by the primary receiver on the performance of multi-hop cognitive amplify-and-forward (AF) relay networks. The athours assume that all involved channels are subject to independent, not necessarily identically distributed Nakagami-m fading and the secondary multi-hop relay network operates in channel state information-assisted AF mode. An analysis of the system performance in terms of outage probability and symbol error rate (SER) is presented. Accordingly, closed-form expressions for the tightly bounded outage probability and SER are formulated which are used for quantifying the impact of the fading channels, the interference power constraint and the number of hops on system performance. More importantly, an asymptotic performance analysis, which intuitively reveals benefits of cooperative diversity of the secondary relay network, is established. The analysis shows that the diversity gain of the considered cognitive relay networks is equal to the minimum of the fading severity parameters of all relaying hops. Also, the interference power constraint imposed by the primary receiver only affects the coding gain of the secondary relay network.

  • 10. Phan, Hoc
    et al.
    Zheng, Fu-Chun
    Chu, Thi My Chinh
    Blekinge Institute of Technology, Faculty of Computing, Department of Communication Systems.
    Physical-layer network coding with multi-antenna transceivers in interference limited environments2016In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 10, no 4, p. 363-371Article in journal (Refereed)
    Abstract [en]

    In this study, the authors first analyse system performance of beamforming amplify-and-forward two-way relay networks with physical-layer network coding under the impact of co-channel interference from multiple surrounding terminals and then propose the associated power allocation strategies. The performance of the two-way communications in terms of outage probability, symbol error rate (SER), and total ergodic channel capacity of the system is quantified. Asymptotic performance analysis for sufficiently high signal-to-noise ratio is also provided to obtain further valuable insights into system designs. Based on the analysis, power allocation strategies to minimise the asymptotic outage probability and SER as well as to maximise the ergodic channel capacity under the total power constraint are developed. The numerical results show that the proposed power allocation approaches outperform equal power allocation given the same total power budget and other system parameters. © The Institution of Engineering and Technology.

  • 11. Salimi, Somayeh
    et al.
    Salmasizadeh, Mahmoud
    Aref, Mohammad Reza
    Generalized Secure Distributed Source Coding with Side Information2010In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 4, no 18, p. 2262-2272Article in journal (Refereed)
    Abstract [en]

    New inner and outer bounds on the achievable compression-equivocation rate region for generalised secure data compression with side information are given that do not match in general. In this setup, two senders, Alice and Charlie intend to transmit information to Bob via channels with limited capacity so that he can reliably reconstruct their observations. The eavesdropper, Eve, has access to one of the channels at each instant and is interested in the source of the same channel at the time. Bob and Eve also have their own observations, which are correlated with Alice's and Charlie's observations. In this model, two equivocation and compression rates are defined with respect to the sources of Alice and Charlie. Furthermore, different special cases are discussed where the inner and outer bounds match. Our model covers the previously obtained results as well.

  • 12.
    Shokri-Ghadikolaei, Hossein
    et al.
    Sharif University of Technology .
    Abdi, Younes
    Nasiri-Kenari, Masoumeh
    Sharif University of Technology .
    Analytical and learning-based spectrum sensing time optimisation in cognitive radio systems2013In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 7, no 5, p. 480-489Article in journal (Refereed)
    Abstract [en]

    In this study, the average throughput maximisation of a secondary user (SU) by optimising its spectrum sensing time is formulated, assuming that a priori knowledge of the presence and absence probabilities of the primary users (PUs) is available. The energy consumed to find a transmission opportunity is evaluated, and a discussion on the impacts of the number of PUs on SU throughput and consumed energy are presented. To avoid the challenges associated with the analytical method, as a second solution, a systematic adaptive neural network-based sensing time optimisation approach is also proposed. The proposed scheme is able to find the optimum value of the channel sensing time without any prior knowledge or assumption about the wireless environment. The structure, performance and cooperation of the artificial neural networks used in the proposed method are explained in detail, and a set of illustrative simulation results is presented to validate the analytical results as well as the performance of the proposed learning-based optimisation scheme.

  • 13.
    Shokri-Ghadikolaei, Hossein
    et al.
    Sharif University of Technology, Iran.
    Nasiri-Kenari, M.
    Sensing matrix setting schemes for cognitive networks and their performance analysis2012In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 6, no 17, p. 3026-3035Article in journal (Refereed)
  • 14.
    Stenumgaard, Peter
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, The Institute of Technology.
    Linder, Sara
    Totalförsvarets Forskningsinstitut.
    Wiklundh, Kia
    Totalförsvarets Forskningsinsitut.
    Extension of the impulsiveness correction factor for several modulation schemes and various interfering signals for interference control in dynamic wireless applications2012In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 6, no 10, p. 1229-1233Article in journal (Refereed)
    Abstract [en]

    The impulsiveness correction factor (ICF) has earlier been proposed as a simple measure for estimating the effect from pulsed interference on binary phase shift keying modulated digital radio systems. The advantage is that with the ICF, large errors introduced by the additive white Gaussian noise interference approximation can be reduced significantly, whereas the simplicity in interference analyses can be maintained. In this study, the ICF is further developed for other modulation schemes, such as M-phase shift keying and M -quadrature amplitude modulation and for a larger set of interference types. The results show that for one pulsed interference signal the ICF is suitable for all investigated modulation schemes. If the interference is a mixtureof modulated and pulsed signals or several pulsed signals the authors suggest and  valuate ways to extend the ICF.

  • 15.
    Wigren, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Wireless interference power estimation for inter-cell interference coordination2015In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 9, no 12, p. 1539-1546Article in journal (Refereed)
  • 16.
    Zenteno, Efrain
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. University of Gävle, Sweden.
    Piazza, Roberto
    Shankar, M. R. Bhavani
    Ronnow, Daniel
    Ottersten, Bjoern
    Multiple-input multiple-output symbol rate signal digital predistorter for non-linear multi-carrier satellite channels2015In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 9, no 16, p. 2053-2059Article in journal (Refereed)
    Abstract [en]

    A digital predistortion (DPD) scheme is presented for non-linear distortion mitigation in multi-carrier satellite communication channels. The proposed DPD has a multiple-input multiple-output architecture similar to data DPD schemes. However, it enhances the mitigation performance of data DPDs using a multi-rate processing algorithm to achieve spectrum broadening of non-linear operators. Compared to single carrier (single-input single-output) signal (waveform) DPD schemes, the proposed DPD has lower digital processing rate reducing the required hardware cost of the predistorter. The proposed DPD outperforms, in total degradation, both data and signal DPD schemes. Further, it performs closest to a channel bound described by an ideally mitigated channel with limited maximum output power.

  • 17.
    Zenteno, Efrain
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. Dept. of Signal Processing, KTH Royal Institute of Technology, Stockholm, Sweden .
    Piazza, Roberto
    Interdisciplinary Centre for Security, Reliability and Trust (SnT), University of Luxembourg, Luxembourg.
    Shankar, M.R. Bhavani
    Interdisciplinary Centre for Security, Reliability and Trust (SnT), University of Luxembourg, Luxembourg.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Ottersten, Björn
    Interdisciplinary Centre for Security, Reliability and Trust (SnT), University of Luxembourg, Luxembourg.
    Multiple-input multiple-output symbol rate signal digital predistorter for non-linear multi-carrier satellite channels2015In: IET Communications, ISSN 1751-8628, E-ISSN 1751-8636, Vol. 9, no 16, p. 2053-2059Article in journal (Refereed)
    Abstract [en]

    A digital predistortion (DPD) scheme is presented for non-linear distortion mitigation in multi-carrier satellite communication channels. The proposed DPD has a multiple-input multiple-output architecture similar to data DPD schemes. However, it enhances the mitigation performance of data DPDs using a multi-rate processing algorithm to achieve spectrum broadening of non-linear operators. Compared to single carrier (single-input single-output) signal (waveform) DPD schemes, the proposed DPD has lower digital processing rate reducing the required hardware cost of the predistorter. The proposed DPD outperforms, in total degradation, both data and signal DPD schemes. Further, it performs closest to a channel bound described by an ideally mitigated channel with limited maximum output power.

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