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  • 1.
    Abramson, Norman
    et al.
    Department of Electrical Engineering, University of Hawaii, USA.
    Sacchi, Claudio
    Information Engineering and Computer Science Department, University of Trento, Italy.
    Bellalta, Boris
    Department of Information and Communication Technologies, Universitat Pompeu Fabra, Spain.
    Vinel, Alexey
    Saint-Petersburg Institute for Informatics and Automation, Russian Academy of Sciences, Russia.
    Multiple access communications in future-generation wireless networks2012Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, s. Art nr 45-Artikkel i tidsskrift (Fagfellevurdert)
  • 2. Al-Saadeh, Osama
    et al.
    Sung, Ki Won
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    A performance comparison of in-band full duplex and dynamic TDD for 5G indoor wireless networks2017Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, artikkel-id 50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In-band full duplex has emerged as a solution for high data rate and low access delay for 5G wireless networks after its feasibility has been demonstrated. However, the impact of the in-band full duplex on the system-level performance of multi-cell wireless networks has not been investigated thoroughly. In this paper, we conduct an extensive simulation study to investigate the performance of in-band full duplex for indoor 5G small cell wireless networks. Particularly, we compare the in-band full duplex with static and dynamic time division duplexing schemes which require much less hardware complexity. We examine the effects of beamforming and interference cancellation under various traffic demands and asymmetry situations in the performance comparison. Our objective is to identify under which condition and with which technology support the in-band full duplex becomes advantageous over the simpler duplexing schemes. Numerical results indicate that for highly utilized wireless networks, in-band full duplex should be combined with interference cancellation and beamforming in order to achieve a performance gain over traditional duplexing schemes. Only then in-band full duplex is considered to be advantageous at any number of active mobile stations in the network and any downlink to uplink traffic proportion. Our results also suggest that in order to achieve a performance gain with the in-band full duplex in both links, the transmit power of the access points and the mobile stations should be comparable.

  • 3.
    Apelfröjd, Rikke
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sternad, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Design and measurement based evaluation of coherent JT CoMP: A study of precoding, user grouping and resource allocation using predicted CSI2014Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 100Artikkel i tidsskrift (Fagfellevurdert)
  • 4.
    Apelfröjd, Rikke
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Sternad, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Design and measurement based evaluations of coherent JT CoMP: a study of precoding, user grouping and resource allocation using predicted CSI2014Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, s. 100-Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Coordinated multipoint (CoMP) transmission provides high theoretic gains in spectral efficiency with coherent joint transmission (JT) to multiple users. However, this requires accurate channel state information at the transmitter (CSIT) and also user groups with spatially compatible users. The aim of this paper is to use measured channels to investigate if significant CoMP gains can still be obtained with channel estimation errors. This turns out to be the case, but requires the combination of several techniques. We here focus on coherent downlink JT CoMP to multiple users within a cluster of cooperating base stations. The use of Kalman predictors is investigated to estimate the complex channel gains at the moment of transmission. It is shown that this can provide sufficient CSIT quality for JT CoMP even for long (> 20 ms) system delays at 2.66 GHz at pedestrian velocities or, for lower delays, at 500 MHz, at vehicular velocities. A user grouping and resource allocation scheme that provides appropriate groups for CoMP is also suggested. It provides performance close to that obtained by exhaustive search at very low complexity, low feedback cost and very low backhaul cost. Finally, a robust linear precoder that takes channel uncertainties into account when designing the precoding matrix is considered. We show that, in challenging scenarios, this provides large gains compared with zero-forcing precoding. Evaluations of these design elements are based on measured channels with realistic noise and intercluster interference assumptions. These show that high JT CoMP gains can be expected, on average over large sets of user positions, when the above techniques are combined - especially in severely intracluster interference limited scenarios.

  • 5.
    Bassoo, Vandana
    et al.
    Victoria University, Australia.
    Tom, Kevin
    Victoria University, Australia.
    Mustafa, A. K.
    Victoria University, Australia.
    Cijvat, Ellie
    Lund University.
    Sjöland, Henrik
    Lund University.
    Faulkner, Mike
    Victoria University; Australia.
    A potential transmitter architecture for future generation green wireless base station2009Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, artikkel-id 821846Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Current radio frequency power amplifiers in 3G base stations have very high power consumption leading to a hefty cost and negative environmental impact. In this paper, we propose a potential architecture design for future wireless base station. Issues associated with components of the architecture are investigated. The all-digital transmitter architecture uses a combination of envelope elimination and restoration (EER) and pulse width modulation (PWM)/pulse position modulation (PPM) modulation. The performance of this architecture is predicted from the measured output power and efficiency curves of a GaN amplifier. 57% efficiency is obtained for an OFDM signal limited to 8 dB peak to average power ratio. The PWM/PPM drive signal is generated using the improved Cartesian sigma delta techniques. It is shown that an RF oversampling by a factor of four meets the WLAN spectral mask, and WCDMA specification is met by an RF oversampling of sixteen.

  • 6.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Inbyggda system (CERES).
    Ström, Erik G.
    Högskolan i Halmstad, Inbyggda system (CERES).
    Bilstrup, Urban
    Högskolan i Halmstad, Inbyggda system (CERES).
    On the ability of the 802.11p MAC method and STDMA to support real-time vehicle-to-vehicle communications2009Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2009, nr 902414, s. 1-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the intelligent transportation systems (ITS) sphere. Many of these new applications require real-time communication with high reliability, meaning that packets must be successfully delivered before a certain deadline. Applications with early deadlines are expected to require direct V2V communications, and the only standard currently supporting this is the upcoming IEEE 802.11p, included in the wireless access in vehicular environment (WAVE) stack. To meet a real-time deadline, timely and predictable access to the channel is paramount. However, the medium access method used in 802.11p, carrier sense multiple access with collision avoidance (CSMA/CA), does not guarantee channel access before a finite deadline. In this paper, we analyze the communication requirements introduced by traffic safety applications, namely, low delay, reliable, real-time communications.We show by simulation of a simple, but realistic, highway scenario, that vehicles using CSMA/CA can experience unacceptable channel access delays and, therefore, 802.11p does not support real-time communications. In addition, we present a potential remedy for this problem, namely, the use of self-organizing time division multiple access (STDMA). The real-time properties of STDMA are investigated by means of the same highway simulation scenario, with promising results.

  • 7.
    Bilstrup, Katrin
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Uhlemann, Elisabeth
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Ström, Erik G.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    Bilstrup, Urban
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Inbyggda system (CERES).
    On the ability of the 802.11p MAC method and STDMA to support real-time vehicle-to-vehicle communications2009Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2009, nr 902414, s. 1-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Traffic safety applications using vehicle-to-vehicle (V2V) communication is an emerging and promising area within the intelligent transportation systems (ITS) sphere. Many of these new applications require real-time communication with high reliability, meaning that packets must be successfully delivered before a certain deadline. Applications with early deadlines are expected to require direct V2V communications, and the only standard currently supporting this is the upcoming IEEE 802.11p, included in the wireless access in vehicular environment (WAVE) stack. To meet a real-time deadline, timely and predictable access to the channel is paramount. However, the medium access method used in 802.11p, carrier sense multiple access with collision avoidance (CSMA/CA), does not guarantee channel access before a finite deadline. In this paper, we analyze the communication requirements introduced by traffic safety applications, namely, low delay, reliable, real-time communications.We show by simulation of a simple, but realistic, highway scenario, that vehicles using CSMA/CA can experience unacceptable channel access delays and, therefore, 802.11p does not support real-time communications. In addition, we present a potential remedy for this problem, namely, the use of self-organizing time division multiple access (STDMA). The real-time properties of STDMA are investigated by means of the same highway simulation scenario, with promising results.

  • 8.
    Blasco-Serrano, Ricardo
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Lv, Jing
    Dresden University of Technology.
    Thobaben, Ragnar
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Jorswieck, Eduard
    Dresden University of Technology.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Multi-antenna transmission for underlay and overlay cognitive radio with explicit message-learning phase2013Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499Artikkel i tidsskrift (Fagfellevurdert)
  • 9.
    Bodin, Ulf
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Wolosz, Krzysztof
    Proportional throughput differentiationwith cognitive load-control on WSN channels2015Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, nr 1, artikkel-id 186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wireless sensor networks are nowadays used in various applications to facilitate monitoring and actuation tasks, e.g., for smart grids and industrial automation. Some of these applications require guarantees or at least assurances on reliability. Such applications expect predictable throughput and delay, which are hard to maintain in environments with changing radio conditions. QoS-aware MAC protocols capable of handling such environments are well explored. They require however protocol changes and are therefore difficult to deploy. This paper presents an application layer forwarding service that offers proportional differentiation while limiting network load to preserve high utilization and predictability. Demands for capacity are expressed as fractions of the overall channel throughput. We show that this service can be implemented with a cognitive load controller (CLC) based on fuzzy logic and quality assessed with utility functions for application layer packet loss and throughput. We evaluate the CLC for 802.15.4 with CSMA/CA through NS-3 simulations showing that it offers the intended service while adjusting load for high overall throughput and low delay

  • 10.
    Castro, Marcel
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Gallucio, Laura
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Rametta, Corrado
    Opportunistic P2P Communications in Delay Tolerant Rural Scenarios2011Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. Januari, artikkel-id 892038Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Opportunistic networking represents a promising paradigm for support of communications, specifically in infrastructure-less scenarios such as remote areas communications. In principle in opportunistic environments, we would like to make available all the applications thought for traditional wired and wireless networks like file sharing and content distribution. In this paper we present a delay tolerant scenario for file sharing applications in rural areas where an opportunistic approach is exploited. In order to support communications, we compare two peer-to-peer (P2P) schemes initially conceived for wireless networks and prove their applicability and usefulness to a DTN scenario where replication of resources can be used to improve the lookup performance and the network can be occasionally connected by mean of a data mule. Simulation results show the suitability of the schemes and allow to derive interesting design guidelines on the convenience and applicability of such approaches

  • 11. Chatzinotas, Symeon
    et al.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Interference mitigation techniques for clustered multicell joint decoding systems2011Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 132, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multicell joint processing has originated from information-theoretic principles as a means of reaching the fundamental capacity limits of cellular networks. However, global multicell joint decoding is highly complex and in practice clusters of cooperating Base Stations constitute a more realistic scenario. In this direction, the mitigation of intercluster interference rises as a critical factor towards achieving the promised throughput gains. In this paper, two intercluster interference mitigation techniques are investigated and compared, namely interference alignment and resource division multiple access. The cases of global multicell joint processing and cochannel interference allowance are also considered as an upper and lower bound to the interference alignment scheme, respectively. Each case is modelled and analyzed using the per-cell ergodic sum-rate throughput as a figure of merit. In this process, the asymptotic eigenvalue distribution of the channel covariance matrices is analytically derived based on free-probabilistic arguments in order to quantify the sum-rate throughput. Using numerical results, it is established that resource division multiple access is preferable for dense cellular systems, while cochannel interference allowance is advantageous for highly sparse cellular systems. Interference alignment provides superior performance for average to sparse cellular systems on the expense of higher complexity.

  • 12.
    Chen, Lei
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Generalizing and Optimizing Fractional Frequency Reuse in Broadband Cellular Radio Access Networks2012Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 230Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For broadband cellular access based on orthogonal frequency divisionmultiple access (OFDMA), fractional frequency reuse (FFR) is one ofthe key concepts for mitigating inter-cell interference and therebyoptimizing cell-edge performance. In standard FFR, the number of OFDMAsub-bands and the reuse factor are both fixed. Whereas this works wellfor an idealized cell pattern, it is neither directly applicable noradequate for real-life networks with very irregular cell layouts. Inthis paper, we generalize the standard FFR to allow for flexibilities inthe total number of sub-bands as well as the number of sub-bands ineach cell-edge zone, enabling network-adaptive FFR. Two powerassignment strategies that use fixed power per sub-band prior tosub-band allocation and apply cell-specific power derived from thenumber of sub-bands allocated to each cell-edge zone, respectively,are investigated. Optimization algorithms based on local search aredeveloped for sub-band allocation to maximize the cell-edgethroughput. Evaluations using networks with realistic radiopropagation conditions demonstrate the applicability of the generalizedand optimized FFR in performance engineering of OFDMA networks.

  • 13. Chong, Z.
    et al.
    Mochaourab, Rami
    Jorswieck, Eduard
    Pricing in Noncooperative Interference Channels for Improved Energy Efficiency2010Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2010Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider noncooperative energy-efficient resource allocation in the interference channel. Energy efficiency is achieved when each system pays a price proportional to its allocated transmit power. In noncooperative game-theoretic notation, the power allocation chosen by the systems corresponds to the Nash equilibrium. We study the existence and characterize the uniqueness of this equilibrium. Afterwards, pricing to achieve energy-efficiency is examined. We introduce an arbitrator who determines the prices that satisfy minimum QoS requirements and minimize total power consumption. This energy-efficient assignment problem is formulated and solved. We compare our setting to that without pricing with regard to energy-efficiency by simulation. It is observed that pricing in this distributed setting achieves higher energy-efficiency indifferent interference regimes.

  • 14.
    Christopoulos, Dimitrios
    et al.
    Univ Luxembourg, Luxembourg.
    Chatzinotas, Symeon
    Univ Luxembourg, Luxembourg.
    Zheng, Gan
    Univ Luxembourg, Luxembourg.
    Grotz, Joel
    SES, Betzdorf, Luxembourg.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Linear and nonlinear techniques for multibeam joint processing in satellite communications2012Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, s. 162-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Existing satellite communication standards such as DVB-S2, operate under highly-efficient adaptive coding and modulation schemes thus making significant progress in improving the spectral efficiencies of digital satellite broadcast systems. However, the constantly increasing demand for broadband and interactive satellite links emanates the need to apply novel interference mitigation techniques, striving towards Terabit throughput. In this direction, the objective of the present contribution is to investigate joint multiuser processing techniques for multibeam satellite systems. In the forward link, the performance of linear precoding is investigated with optimal nonlinear precoding (i.e., dirty article coding) acting as the upper performance limit. To this end, the resulting power and precoder design problems are approached through optimization methods. Similarly, in the return link the concept of linear filtering (i.e., linear minimum mean square error) is studied with the optimal successive interference cancelation acting as the performance limit. The derived capacity curves for both scenarios are compared to conventional satellite systems where beams are processed independently and interbeam interference is mitigated through a four color frequency reuse scheme, in order to quantify the potential gain of the proposed techniques.

  • 15.
    Chu, Thi My Chinh
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för kommunikationssystem.
    Phan, Hoc
    Univ Reading, GBR.
    Hybrid spectrum access with relay assisting both primary and secondary networks under imperfect spectrum sensing2016Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, artikkel-id 244Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper proposes a novel hybrid interweave-underlay spectrum access for a cognitive amplify-and-forward relay network where the relay forwards the signals of both the primary and secondary networks. In particular, the secondary network (SN) opportunistically operates in interweave spectrum access mode when the primary network (PN) is sensed to be inactive and switches to underlay spectrum access mode if the SN detects that the PN is active. A continuous-time Markov chain approach is utilized to model the state transitions of the system. This enables us to obtain the probability of each state in the Markov chain. Based on these probabilities and taking into account the impact of imperfect spectrum sensing of the SN, the probability of each operation mode of the hybrid scheme is obtained. To assess the performance of the PN and SN, we derive analytical expressions for the outage probability, outage capacity, and symbol error rate over Nakagami-m fading channels. Furthermore, we present comparisons between the performance of underlay cognitive cooperative radio networks (CCRNs) and the performance of the considered hybrid interweave-underlay CCRN in order to reveal the advantages of the proposed hybrid spectrum access scheme. Eventually, with the assistance of the secondary relay, performance improvements for the PN are illustrated by means of selected numerical results.

  • 16.
    Conchon, Emmanuel
    et al.
    Université de Toulouse.
    Pérennou, Tanguy
    Université de Toulouse.
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Diaz, Michel
    W-NINE: A Two-stage Emulation Platform for Mobile and Wireless Systems2010Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2010, s. 1-20Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    More and more applications and protocols are now running on wireless networks. Testing         the implementation of such applications and protocols is a real challenge as the position of the mobile terminals and environmental effects strongly affect the overall performance. Network emulation is often perceived as a good trade-off between experiments on operational wireless networks and discrete-event simulations on Opnet or ns-2. However, ensuring repeatability and realism in network emulation while taking into account mobility in a wireless environment is very difficult. This paper proposes a network emulation platform, called W-NINE, based on off-line computations preceding online pattern-based traffic shaping. The underlying concepts of repeatability, dynamicity, accuracy, and realism are defined in the emulation context. Two different simple case studies illustrate the validity of our approach with respect to these concepts.

  • 17.
    Cottatellucci, Laura
    et al.
    Eurecom, France.
    Mestre, Xavier
    CTTC, Spain.
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Ribeiro, Alejandro
    University of Minnesota, USA.
    Cooperative Communications in Wireless Networks: Editorial Material in EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING2009Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, artikkel-id 768314Artikkel i tidsskrift (Annet vitenskapelig)
  • 18.
    Dely, Peter
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Bayer, Nico
    Telekom Innovation Laboratories.
    Einsiedler, Hans
    Telekom Innovation Laboratories.
    Peylo, Christoph
    Telekom Innovation Laboratories.
    Optimization of WLAN associations considering handover costs2012Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 255Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In Wireless Local Area Network (WLAN) hotspots the coverage areas of Access Points (APs) often overlap considerably. Current state of the art optimization models find the optimal AP for each user station by balancing the load across the network. Recent studies have shown that in typical commercial WLAN hotspots the median connection duration is short. In such dynamic network settings the mentioned optimization models might cause many handovers between APs to accommodate for user arrivals or mobility. We introduce a new mixed integer linear optimization problem that allows to optimize handovers but takes into account the costs of handovers such as signaling and communication interruption. Using our model and extensive numeric simulations we show that disregarding the handover costs leads to low performance. Based on this insight we design a new optimization scheme that uses estimates of future station arrivals and mobility patterns. We show that our scheme outperforms current optimization mechanisms and is robust against estimation errors

  • 19.
    Do, Tan Tai
    et al.
    KTH, Skolan för elektro- och systemteknik (EES).
    Kim, Su Min
    Oechtering, Tobias J.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori.
    Peters, Gunnar
    Waveform domain framework for capacity analysis of uplink WCDMA systems2015Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, artikkel-id 253Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper investigates the capacity limit of an uplink WCDMA system considering a continuous-time waveform signal. Various realistic assumptions are incorporated into the problem, which make the study valuable for performance assessment of real cellular networks to identify potentials for performance improvements in practical receiver designs. An equivalent discrete-time channel model is derived based on sufficient statistics for optimal decoding of the transmitted messages. The capacity regions are then characterized using the equivalent channel considering both finite constellation and Gaussian distributed input signals. The capacity with sampling at the receiver is also provided to exemplify the performance loss due to a typical post-processing at the receiver. Moreover, we analyze the asymptotic capacity when the signal-to-noise ratio goes to infinity. The conditions to simultaneously achieve the individual capacities are derived, which reveal the impacts of signature waveform space, channel frequency selectivity and signal constellation on the system performance.

  • 20. Duong, Quang Trung
    et al.
    Zepernick, Hans-Jürgen
    On the Performance Gain of Hybrid Decode-Amplify-Forward Cooperative Communications2009Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2009Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we investigate the performance of adaptive decode-forward (ADF), amplify-forward (AF), and hybrid decode-amplify-forward (HDAF) relaying protocol. In particular, we derive the closedform expression of symbol error probability (SEP) for these three relaying protocols. For the AF protocol, we derive a simpler and more tractable final result than previously published work [1]. Furthermore, analyzing the high signal-to-noise ratio (SNR) regime, we derive an asymptotically tight approximation for SEP. Especially, for the AF protocol, our SEP approximation is tighter than the result in [2]. The SEP approximation is used to assess an important aspect between the three different relaying protocols, i.e., the SEP performance gain of HADF over the two conventional relaying schemes ADF and AF. It is shown that the performance gain of HDAF over ADF and AF significantly depends on the relative value of channel conditions between source-to-relay and relay-to- estination link (relay channels). Interestingly, it is shown that the HDAF protocol has no benefit compare to the two others if the relay is located close to the source. In contrast, the performance gains of HDAF over the ADF and AF scheme are remarkably large as the relay moves nearby the destination. Specifically, the numerical results given as well as our analysis indicate that for QPSK modulation, HDAF outperforms ADF and AF with a performance improvement by 5 dB and 6 dB, respectively.

  • 21. Gacanin, Haris
    et al.
    Sjödin, Tomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Adachi, Fumiyuki
    On Channel Estimation for Analog Network Coding in a Frequency-Selective Fading Channel2011Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, artikkel-id 980430Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recently, broadband analog network coding (ANC) was introduced for high-speed transmission over the wireless (frequency-selective fading) channel. However, ANC requires the knowledge of channel state information (CSI) for self-information removal and coherent signal detection. In ANC, the users' pilot signals interfere during the first slot, which renders the relay unable to estimate CSIs of different users, and, consequently, four time-slot pilot-assisted channel estimation (CE) is required to avoid interference. Naturally, this will reduce the capacity of ANC scheme. In this paper, we theoretically analyze the bit error rate (BER) performance of bi-directional broadband ANC communication based on orthogonal frequency division multiplexing (OFDM) radio access. We also theoretically analyze the performance of the channel estimator's mean square error (MSE). The analysis is based on the assumption of perfect timing and frequency synchronization. The achievable BER performance and the estimator's MSE for broadband ANC is evaluated by numerical and computer simulation. We discuss how, and by how much, the imperfect knowledge of CSI affects the BER performance of broadband ANC. It is shown that the CE scheme achieves a slightly higher BER in comparison with ideal CE case for a low and moderate mobile terminal speed in a frequency-selective fading channel.

  • 22.
    Garcia-Garcia, Laura
    et al.
    Dept. of Signals, Systems and Radiocommunications Universidad Politécnica de Madrid (UPM), 28040 Madrid (Spain) .
    Jaldén, Niklas
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Lindmark, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Zetterberg, Per
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    de Haro, Leandro
    Dept. of Signals, Systems and Radiocommunications Universidad Politécnica de Madrid (UPM), 28040 Madrid (Spain) .
    Measurements of MIMO indoor channels at 1800 MHz with multiple indoor and outdoor base stations2007Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper proposes several configurations for multiple base stations in indoor MIMO systems and compares their performance. The results are based on channel measurements realized with a MIMO testbed. The receiver was moved along several routes and floors on an office building. Both outdoor and indoor locations are considered for the transmitters or base stations, which allow the analysis of not only indoor but also outdoor-to-indoor environment. The use of 2 base stations with different system level combinations of the two is analyzed. We show that the 2 x 4 configuration with base station selection provides almost as good performance as a 4 x 4 full water-filling scheme when the 2 base stations are placed at different locations. Also the spatial correlation properties for the different configurations are analyzed and the importance of considering path loss when evaluating capacity is highlighted.

  • 23.
    Gustafsson, Fredrik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Gunnarsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Lindgren, David
    Swedish Defence Research Agency, Linköping, Sweden.
    Sensor models and localization algorithms for sensor networks based on received signal strength2012Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 1, nr 16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Received signal strength (RSS) can be used in sensor networks as a ranging measurement for positioning and localization applications. This contribution studies the realistic situation where neither the emitted power nor the power law decay exponent be assumed to be known. The application in mind is a rapidly deployed network consisting of a number of sensor nodes with low-bandwidth communication, each node measuring RSS of signals traveled through air (microphones) and ground (geophones). The first contribution concerns validation of a model in logarithmic scale, that is, linear in the unknown nuisance parameters (emitted power and power loss constant). The parameter variation is studied over time and space. The second contribution is a localization algorithm based on this model, where the separable least squares principle is applied to the non-linear least squares (NLS) cost function, after which a cost function of only the unknown position is obtained. Results from field trials are presented to illustrate the method, together with fundamental performance bounds. The ambition is to pave the way for sensor configuration design and more thorough performance evaluations as well as filtering and target tracking aspects.

  • 24.
    Hasani, Bilal
    et al.
    KTH, Skolan för elektro- och systemteknik (EES).
    Zafar, Saima
    Akbar, Ali Hammad
    Magsi, Babar Ali
    Collaborative routing and data delivery architecture for commercial wireless sensor networks2013Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, nr 1, s. 54-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lately, wireless sensor network applications have emerged for provision of commercial services to end users. This results in commercial deployment of sensor networks which is as an important research area due to a number of design and quality of service challenges. An important technical challenge for sensor service provision to end users is managing dynamic network conditions such as unreliability of sensor nodes and network links which results in frequent service outages. This research is aimed at addressing this challenge. It presents a novel architecture which utilizes the availability of multiple sensor networks under different administrative domains, deployed in an area such that maximum network connectivity and high service availability are ensured. The architecture incorporates modifications and enhancements at the medium access control and the routing layers of sensor nodes for the collaborative operation of sensor networks. The design is based on IEEE 802.15.4 standard and ad hoc on demand distance vector routing protocol. The proposed architecture is mathematically analyzed with regards to overheads associated with the design such as routing and communication, and techniques to minimize these overheads are recommended. Through simulations using OMNET++, we show that the proposed architecture effectively provides connectivity for disconnected nodes achieving an overall increase in throughput for all the cooperating networks.

  • 25. Hult, Tommy
    WCDMA Uplink Interference Assessment from Multiple High Altitude Platform Configurations2008Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. vol. 2008, nr Special Issue on Advanced Communication Techniques and Applications for High-Altitude PlatformsArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate the possibility of multiple high altitude platform (HAP) coverage of a common cell area using a wideband code division multiple access (WCDMA) system. In particular, we study the uplink system performance of the system. The results show that depending on the traffic demand and the type of service used, there is a possibility of deploying 3-6 HAPs covering the same cell area. The results also show the effect of cell radius on performance and the position of the multiple HAP base stations which give the worst performance.

  • 26.
    Jacobsson, Martin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Rohner, Christian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Comparing wireless flooding protocols using trace-based simulations2013Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, s. 169:1-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Most wireless multi-hop networks, such as ad hoc networks and wireless sensor networks, need network-wide broadcasting, which is best done with a flooding protocol. In this article, we use packet trace information from a real test-bed network to define a simulator for flooding protocol performance studies. Five protocols are compared using the simulator. Trace-based simulations promise to have the benefits of the simulator, such as reducing required work effort and repeatability but still produce results close to the real test-bed or deployment. We propose and evaluate different approaches on how to use collected trace data and how to tune the parameters to achieve the best possible accuracy in comparison with actual test-bed measurements. We study the resulting accuracy of the model so that performance studies know with what confidence a certain conclusion can be made. Using the new trace-based model and knowing its accuracy, we compare the five flooding protocols to gain additional insights into their performance. Finally, by modifying the trace data, we study how real-world effects, such as links with in-between qualities and asymmetric links, influence the different flooding protocols.

  • 27.
    Jaldén, Niklas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Zetterberg, Per
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Garcia, Laura
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Inter-and Intrasite Correlation of Large Scale Parameters from Macro Cellular Measurements at 1800MHz2007Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2007Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein, the inter- and intra-site correlation propertiesof shadow fading and power-weighted angular spreadat both the mobile station and the base station are studiedutilizing narrow band multi-site MIMO measurements in the1800MHz band. The influence of the distance between two basestations on the correlation is studied in an urban environment.Measurements have been conducted for two different situations,widely separated as well as closely positioned base stations. Novelresults regarding the correlation of the power-weighted anglespread between base station sites with different separations arepresented. Furthermore, the measurements and analysis presentedherein confirm the autocorrelation and cross-correlationproperties of the shadow fading and the angle spread that havebeen observed in previous studies.

  • 28.
    Jorswieck, Eduard A.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Sezgin, Aydin
    Information Systems Laboratory, Computer Forum, Department of Electrical Engineering, School of Engineering, Stanford University, USA.
    Paulraj, Arogyasvsami
    Information Systems Laboratory, Computer Forum, Department of Electrical Engineering, School of Engineering, Stanford University, USA.
    Guaranteed performance region in fading orthogonal space-time coded broadcast channels2008Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recently, the capacity region of the MIMO broadcast channel (BC) was completely characterized and duality between MIMO multiple access channel (MAC) and MIMO BC with perfect channel state information (CSI) at transmitter and receiver was established. In this work, we propose a MIMO BC approach in which only information about the channel norm is available at the base and hence no joint beamforming and dirty paper precoding (DPC) can be applied. However, a certain set of individual performances in terms of MSE or zero-outage rates can be guaranteed at any time by applying an orthogonal space-time block code (OSTBC). The guaranteed MSE region without superposition coding is characterized in closed form and the impact of diversity, fading statistics, and number of transmit antennas and receive antennas is analyzed. Finally, six CSI and precoding scenarios with different levels of CSI and precoding are compared numerically in terms of their guaranteed MSE region. Depending on the long-term SNR, superposition coding as well as successive interference cancellation (SIC) with norm feedback performs better than linear precoding with perfect CSI.

  • 29.
    Jorswieck, Eduard A.
    et al.
    Dresden University of Technology (TUD), Germany.
    Sezgin, Aydin
    Information Systems Laboratory, Stanford University, USA.
    Zhang, Xi
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Throughput versus Fairness: Channel-Aware Scheduling in Multiple Antenna Downlink2009Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, s. 271540-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Channel aware and opportunistic scheduling algorithms exploit the channel knowledge and fading to increase the average throughput. Alternatively, each user could be served equally in order to maximize fairness. Obviously, there is a tradeoff between average throughput and fairness in the system. In this paper, we study four representative schedulers, namely the maximum throughput scheduler (MTS), the proportional fair scheduler (PFS), the (relative) opportunistic round robin scheduler (ORS), and the round robin scheduler (RRS) for a space-time coded multiple antenna downlink system. The system applies TDMA based scheduling and exploits the multiple antennas in terms of spatial diversity. We show that the average sum rate performance and the average worst-case delay depend strongly on the user distribution within the cell. MTS gains from asymmetrical distributed users whereas the other three schedulers suffer. On the other hand, the average fairness of MTS and PFS decreases with asymmetrical user distribution. The key contribution of this paper is to put these tradeoffs and observations on a solid theoretical basis. Both the PFS and the ORS provide a reasonable performance in terms of throughput and fairness. However, PFS outperforms ORS for symmetrical user distributions, whereas ORS outperforms PFS for asymmetrical user distribution.

  • 30.
    Katselis, Dimitrios
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Rojas, Cristian R.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Bengtsson, Mats
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Björnson, Emil
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Bombois, Xavier
    Delft University of Technology.
    Shariati, Nafiseh
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Jansson, Magnus
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Hjalmarsson, Håkan
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Training sequence design for MIMO channels: an application-oriented approach2013Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2013, s. 245-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, the problem of training optimization for estimating a multiple-input multiple-output (MIMO) flat fading channel in the presence of spatially and temporally correlated Gaussian noise is studied in an application-oriented setup. So far, the problem of MIMO channel estimation has mostly been treated within the context of minimizing the mean square error (MSE) of the channel estimate subject to various constraints, such as an upper bound on the available training energy. We introduce a more general framework for the task of training sequence design in MIMO systems, which can treat not only the minimization of channel estimator's MSE but also the optimization of a final performance metric of interest related to the use of the channel estimate in the communication system. First, we show that the proposed framework can be used to minimize the training energy budget subject to a quality constraint on the MSE of the channel estimator. A deterministic version of the 'dual' problem is also provided. We then focus on four specific applications, where the training sequence can be optimized with respect to the classical channel estimation MSE, a weighted channel estimation MSE and the MSE of the equalization error due to the use of an equalizer at the receiver or an appropriate linear precoder at the transmitter. In this way, the intended use of the channel estimate is explicitly accounted for. The superiority of the proposed designs over existing methods is demonstrated via numerical simulations.

  • 31. Khattak, Rabiullah
    et al.
    Sandberg, Sara
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Jointly optimized rate-compatible UEP-LDPC codes for half-duplex co-operative relay networks2014Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2014, artikkel-id 22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper addresses the design of low-density parity-check (LDPC) codes for half-duplex co-operative relay networks. Structured rate-compatible codes with unequal error protection (UEP) are designed through joint optimization of the codes for the channels between source and relay and source and destination. The proposed codes clearly outperform simpler LDPC codes which are not optimized for relay channels and puncturing-based rate-compatible LDPC codes, and they show a significant performance improvement over the direct link communication depending on the position of relay. The optimization algorithm for the proposed codes is based on density evolution using the Gaussian approximation and optimal variable node degree distributions are found through iterative linear programming. Interestingly, they anyhow show performance which is almost comparable to the performance of codes optimized through a more complex non-linear optimization algorithm. We analyze the performance of our proposed codes with short, medium and long block lengths, and with low and high rates under realistic assumptions, i.e., imperfect decoding of the codeword at relay and variant signal-to-noise ratio within a single codeword.

  • 32.
    Kuiper, Erik
    et al.
    Saab Aeronautical, Linkoping, Sweden .
    Nadjm-Tehrani, Simin
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system. Linköpings universitet, Tekniska högskolan.
    Yuan, Di
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    A framework for performance analysis of geographic delay-tolerant routing2012Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, nr 184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A major tool used for evaluating routing protocols in ad hoc and delay-tolerant networks is simulation. Whereas the results from simulations give good insights, they are limited to the specific scenario set-up that is used. If the scenario changes, new and often time-consuming simulations have to be run. Moreover, the simulation time in packet-level simulators with fairly realistic physical layer implementation, such as ns-2, generally grows rapidly in the number of nodes. This practically limits the number of nodes in a simulation, even if the limit can be extended by the use of simulation federations. Larger scenarios can also be facilitated by the use of more abstraction in the physical layer; abstractions that may impact the validity of the results. In this article, we present the forward-wait framework--a mathematical model describing the packet movements for opportunistic geographic delay-tolerant routing protocols. By describing packet movements as a sequence of alternating forwarding and waiting phases, the framework can accurately predict the routing performance. Key input parameters to the framework are random variables describing the forwarding and waiting phases. We show how the properties of the random variables can be derived, both via abstract modeling and small scale ns-2 simulation data. The model is then used to demonstrate the prediction capabilities of the framework in providing results that are close to the (much slower) packet-level simulations.

  • 33.
    Li, Xueru
    et al.
    Tsinghua University, Peoples R China.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Erik G
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Zhou, Shidong
    Tsinghua University, Peoples R China.
    Wang, Jing
    Tsinghua University, Peoples R China.
    Massive MIMO with multi-cell MMSE processing: exploiting all pilots for interference suppression2017Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, artikkel-id 117Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new state-of-the-art multi-cell minimum mean square error (M-MMSE) scheme is proposed for massive multiple-input-multiple-output (MIMO) networks, which includes an uplink MMSE detector and a downlink MMSE precoder. Contrary to conventional single-cell schemes that suppress interference using only channel estimates for intra-cell users, our scheme shows the optimal way to suppress both intra-cell and inter-cell interference instantaneously by fully utilizing the available pilot resources. Specifically, let K and B denote the number of users per cell and the number of orthogonal pilot sequences in the network, respectively, where beta = B/K is the pilot reuse factor. Our scheme utilizes all B channel directions that can be estimated locally at each base station, to actively suppress both intra-cell and inter-cell interference. Our scheme is practical and general, since power control, imperfect channel estimation, and arbitrary pilot allocation are all accounted for. Simulations show that significant spectral efficiency (SE) gains are obtained over the conventional single-cell MMSE scheme and the multi-cell zero-forcing (ZF) scheme. Furthermore, large-scale approximations of the uplink and downlink signal-to-interference-and-noise ratios (SINRs) are derived, which are tight in the large-system limit. These approximations are easy to compute and very accurate even for small system dimensions. Using these SINR approximations, a low-complexity power control algorithm is further proposed to maximize the sum SE.

  • 34. Limmanee, A
    et al.
    Dey, Subhrakanti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Nekouei, E
    Optimal power policies and throughput scaling analyses in fading cognitive broadcast channels with primary outage probability constraint2014Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, s. 35-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper focuses on a spectrum-sharing-based fading cognitive radio broadcast channel (BC) with a single-antenna secondary base station (SBS) and M single-antenna secondary receivers (SRs) utilizing the same spectrum band with a delay-sensitive primary user (PU). The service-quality requirement for the primary user is set by an outage probability constraint (POC). We address the optimal power allocation problem for the SBS ergodic sum capacity (ESC) maximization in the secondary BC network subject to POC and a transmit power constraint at SBS specified by either a long-term or a short-term power constraint. The optimality conditions reveal that in each joint channel state, the SBS allocates transmission power to the only one selected SR with the highest value of a certain metric consisting of the ratio of the SR's direct channel power gain and the sum of interference power and noise power at the SR. Then, the secondary network throughput scaling analysis as the number of SRs becomes large, is also investigated, showing that if PU applies a truncated channel inversion (TCI) power policy, the SBS ESC scales like epsilon(p) log(log M) where epsilon(p) is the PU outage probability threshold. To reduce the amount of channel side information (CSI) transferred between the two networks, we propose a suboptimal transmission scheme which requires only 1-bit feedback from the delay-sensitive PR (partial CSI). We show that the new power control policy is asymptotically optimal, i.e. the SBS ESC under this reduced feedback scheme still scales like epsilon(p) log(log M).

  • 35. Liu, Jiangchuan
    et al.
    Cao, Jiannong
    Li, Xiang-Yang
    Sun, Limin
    Wang, Dan
    Ngai, Edith C.-H.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Datorteknik.
    Design, Implementation, and Evaluation of Wireless Sensor Network Systems2010Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, s. 439890:1-2Artikkel, forskningsoversikt (Annet vitenskapelig)
  • 36. Mohammed, Abbas
    et al.
    Arnon, Shelomi
    Grace, David
    Mondin, Marina
    Miura, R
    Advanced Communication Techniques and Applications for High-Altitude Platforms2008Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499Artikkel i tidsskrift (Fagfellevurdert)
  • 37.
    Mowlér, Marc
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Lindmark, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Larsson, Erik G.
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Joint estimation of mutual coupling, element factor, and phase center in antenna arrays2007Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2007, nr 1, s. 030684-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel method is proposed for estimation of the mutual coupling matrix of an antenna array. The method extends previous work by incorporating an unknown phase center and the element factor (antenna radiation pattern) in the model, and treating them as nuisance parameters during the estimation of coupling. To facilitate this, a parametrization of the element factor based on a truncated Fourier series is proposed. The performance of the proposed estimator is illustrated and compared to other methods using data from simulations and measurements, respectively. The Cramer-Rao bound (CRB) for the estimation problem is derived and used to analyze how the required amount of measurement data increases when introducing additional degrees of freedom in the element factor model. We find that the penalty in SNR is 2.5 dB when introducing a model with two degrees of freedom relative to having zero degrees of freedom. Finally, the tradeoff between the number of degrees of freedom and the accuracy of the estimate is studied. A linear array is treated in more detail and the analysis provides a specific design tradeoff.

  • 38.
    Mowlér, Marc
    et al.
    Royal Institute of Technology (KTH).
    Lindmark, Björn
    Royal Institute of Technology (KTH).
    Larsson, Erik G.
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska högskolan.
    Ottersten, Björn
    Royal Institute of Technology (KTH).
    Joint Estimation of Mutual Coupling, Element Factor, and Phase Center in Antenna Arrays2007Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2007Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel method is proposed for estimation of the mutual coupling matrix of an antenna array. The method extends previous work by incorporating an unknown phase center and the element factor (antenna radiation pattern) in the model, and treating them as nuisance parameters during the estimation of coupling. To facilitate this, a parametrization of the element factor based on a truncated Fourier series is proposed. The performance of the proposed estimator is illustrated and compared to other methods using data from simulations and measurements, respectively. The Cramér-Rao bound (CRB) for the estimation problem is derived and used to analyze how the required amount of measurement data increases when introducing additional degrees of freedom in the element factor model. We find that the penalty in SNR is 2.5 dB when introducing a model with two degrees of freedom relative to having zero degrees of freedom. Finally, the tradeoff between the number of degrees of freedom and the accuracy of the estimate is studied. A linear array is treated in more detail and the analysis provides a specific design tradeoff.

  • 39.
    Mudesir, Abdurazak
    et al.
    Jacobs University Bremen.
    Bode, Mathias
    Jacobs University Bremen.
    Sung, Ki Won
    The University of Edinburgh.
    Haas, Harald
    The University of Edinburgh.
    Analytical SIR for Self-Organizing Wireless Networks2009Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The signal to interference ratio (SIR) in the presence of multipath fading, shadowing and path loss is a valuable parameter for studying the capacity of a wireless system. This paper presents a new generalized path loss equation that takes into account the large-scale path loss as well as the small-scale multipath fading. The probability density function (pdf) of the SIR for self-organising wireless networks with Nakagami-mchannel model is analytically derived using the new path loss equation. We chose the Nakagami-mchannel fading model because it encompasses a large class of fading channels. The results presented show good agreement between the analytical and Monte Carlo- based methods. Furthermore, the pdf of the signal to interference plus noise ratio (SINR) is provided as an extension to the SIR derivation. The analytical derivation of the pdf for a single interferer in this paper lays a solid foundation to calculate the statistics for multiple interferers.

  • 40.
    Mueller, Axel
    et al.
    Huawei Technology Co Ltd, France; SUPELEC, France.
    Kammoun, Abla
    SUPELEC, France; King Abdullah University of Science and Technology, Saudi Arabia.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten. SUPELEC, France.
    Debbah, Merouane
    Huawei Technology Co Ltd, France; SUPELEC, France.
    Linear precoding based on polynomial expansion: reducing complexity in massive MIMO2016Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, nr 63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Massive multiple-input multiple-output (MIMO) techniques have the potential to bring tremendous improvements in spectral efficiency to future communication systems. Counterintuitively, the practical issues of having uncertain channel knowledge, high propagation losses, and implementing optimal non-linear precoding are solved more or less automatically by enlarging system dimensions. However, the computational precoding complexity grows with the system dimensions. For example, the close-to-optimal and relatively "antenna-efficient" regularized zero-forcing (RZF) precoding is very complicated to implement in practice, since it requires fast inversions of large matrices in every coherence period. Motivated by the high performance of RZF, we propose to replace the matrix inversion and multiplication by a truncated polynomial expansion (TPE), thereby obtaining the new TPE precoding scheme which is more suitable for real-time hardware implementation and significantly reduces the delay to the first transmitted symbol. The degree of the matrix polynomial can be adapted to the available hardware resources and enables smooth transition between simple maximum ratio transmission and more advanced RZF. By deriving new random matrix results, we obtain a deterministic expression for the asymptotic signal-to-interference-and-noise ratio (SINR) achieved by TPE precoding in massive MIMO systems. Furthermore, we provide a closed-form expression for the polynomial coefficients that maximizes this SINR. To maintain a fixed per-user rate loss as compared to RZF, the polynomial degree does not need to scale with the system, but it should be increased with the quality of the channel knowledge and the signal-to-noise ratio.

  • 41.
    Nilsson, Björn
    et al.
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Bengtsson, Lars
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Svensson, Bertil
    Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    An Energy and Application Scenario Aware Active RFID Protocol2010Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2010, nr Article ID 432938, s. 15-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The communication protocol used is a key issue in order to make the most of the advantages of active RFID technologies. In this paper we introduce a carrier sense medium access data communication protocol that dynamically adjusts its back-off algorithm to best suit the actual application at hand. Based on a simulation study of the effect on tag energy cost, read-out delay, and message throughput incurred by some typical back-off algorithms in a CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) active RFID protocol, we conclude that by dynamic tuning of the initial contention window size and back-off interval coefficient, tag energy consumption and read-out delay can be significantly lowered. We show that it is possible to decrease the energy consumption per tag payload delivery with more than 10 times, resulting in a 50% increase in tag battery lifetime. We also discuss the advantage of being able to predict the number of tags present at the RFID-reader as well as ways of doing it.

  • 42.
    Nordqvist, Peter
    et al.
    KTH, Tidigare Institutioner                               , Signaler, sensorer och system.
    Leijon, Arne
    KTH, Tidigare Institutioner                               , Signaler, sensorer och system.
    Speech Recognition in Hearing Aids2004Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499Artikkel i tidsskrift (Annet vitenskapelig)
  • 43. O'Droma, Máirtín
    et al.
    Rupp, Markus
    Koucheryavy, Yevgeni
    Kassler, Andreas
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Advances in Quality and Performance Assessment for Future Wireless Communication Services2010Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2010, s. 1-3Artikkel i tidsskrift (Fagfellevurdert)
  • 44.
    Osipov, Evgeny
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Tschudin, Christian
    University of Basel.
    TCP-friendly bandwidth sharing in mobile ad hoc networks: from theory to reality2007Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article addresses a problem of the severe unfairness between multiple TCP sessions in a wireless context also known as "TCP capture" phenomenon. We present an adapted max-min fairness framework to the specifics of MANETs. We introduce a practically implementable cross-layer network architecture which enforces our formal model. We have verified with simulations and real world experiments that under our adaptive rate limiting scheme unfair behavior virtually vanishes. The direct consequence of this work guaranteed stable services for TCP-based applications in MANETs, including traditional FTP, web as well as for UDP-based sessions.

  • 45.
    Phan, Hoc
    et al.
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Duong, Quang Trung
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Zepernick, Hans-Jürgen
    Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation.
    Shu, Lei
    Adaptive transmission in MIMO AF relay networks with orthogonal space-time block codes over Nakagami-m fading2012Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, nr 11Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, we apply different adaptive transmission techniques to dual-hop multiple-input multiple-output amplify-and-forward relay networks using orthogonal space-time block coding over independent Nakagami-m fading channels. The adaptive techniques investigated are optimal simultaneous power and rate (OSPR), optimal rate with constant power (ORCP), and truncated channel inversion with fixed rate (TCIFR). The expressions for the channel capacity of OSPR, ORCP, and TCIFR, and the outage probability of OSPR, and TCIFR are derived based on the characteristic function of the reciprocal of the instantaneous signal-to-noise ratio (SNR) at the destination. For sufficiently high SNR, the channel capacity of ORCP asymptotically converges to OSPR while OSPR and ORCP achieve higher channel capacity compared to TCIFR. Although TCIFR suffers from an increase in the outage probability relative to OSPR, it provides the lowest implementation complexity among the considered schemes. Along with analytical results, we further adopt Monte Carlo simulations to validate the theoretical analysis.

  • 46. Pérennou, Tanguy
    et al.
    Brunström, Anna
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Hall, Tomas
    Garcia, Johan
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap. Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Centrum för HumanIT.
    Hurtig, Per
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT, Avdelningen för datavetenskap.
    Emulating Opportunistic Networks with KauNet Triggers2011Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2011Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In opportunistic networks, the availability of an end-to-end path is no longer required. Instead opportunistic networks may take advantage of temporary connectivity opportunities. Opportunistic networks present a demanding environment for network emulation as the traditional emulation setup, where application/transport endpoints only send and receive packets from the network following a black box approach, is no longer applicable. Opportunistic networking protocols and applications additionally need to react to the dynamics of the underlying network beyond what is conveyed through the exchange of packets. In order to support IP-level emulation evaluations of applications and protocols that react to lower layer events, we have proposed the use of emulation triggers. Emulation triggers can emulate arbitrary cross-layer feedback and can be synchronized with other emulation effects. After introducing the design and implementation of triggers in the KauNet emulator, we describe the integration of triggers with the DTN2 reference implementation and illustrate how the functionality can be used to emulate a classical DTN data-mule scenario.

  • 47.
    Rahmani, Rahim
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Åhlund, C.
    Luleå University of Technology, Sweden.
    Kanter, Theo
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Design of active queue management for robust control on access router for heterogeneous networks2011Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2011, s. Art. no. 946498-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Internet architecture is a packet switching technology that allows dynamic sharing of bandwidth among different flows with in an IP network. Packets are stored and forwarded from one node to the next until reaching their destination. Major issues in this integration are congestion control and how to meet different quality of service requirements associated with various services. In other words streaming media quality degrades with increased packet delay and jitter caused by network congestion. To mitigate the impact of network congestion, various techniques have been used to improve multimedia quality and one of those techniques is Active Queue Management (AQM). Access routers require a buffer to hold packets during times of congestion. A large buffer can absorb the bursty arrivals, and this tends to increase the link utilizations but results in higher queuing delays. Traffic burstiness has a considerable negative impact on network performance. AQM is now considered an effective congestion control mechanism for enhancing transport protocol performance over wireless links. In order to have good link utilization, it is necessary for queues to adapt to varying traffic loads. This paper considers a particular scheme which is called Adaptive AQM (AAQM) and studies its performance in the presence of feedback delays and its ability to maintain a small queue length as well as its robustness in the presence of traffic burstiness. The paper also presents a method based on the well-known Markov Modulated Poisson Process (MPP) to capture traffic burstiness and buffer occupancy. To demonstrate the generality of the presented method, an analytic model is described and verified by extensive simulations of different adaptive AQM algorithms. The analysis and simulations show that AAQM outperforms the other AQMs with respect to responsiveness and robustness. © 2011 Rahim Rahmani et al.

  • 48.
    Rahmani, Rahim
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Åhlund, Christer
    Kanter, Theo
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Design of active queue management for robust control on access router for heterogeneous networks2011Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, artikkel-id 946498Artikkel i tidsskrift (Fagfellevurdert)
  • 49.
    Rahmani, Rahim
    et al.
    Mittuniversitetet.
    Åhlund, Christer
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Datavetenskap.
    Kanter, Theo
    Mittuniversitetet.
    Design of active queue management for robust control on access router for heterogeneous networks2011Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2011, artikkel-id 946498Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Internet architecture is a packet switching technology that allows dynamic sharing of bandwidth among different flows with in an IP network. Packets are stored and forwarded from one node to the next until reaching their destination. Major issues in this integration is congestion control and how to meet different quality of service requirements associated with various services. In other words streaming media quality degrades with increased packet delay and jitter caused by network congestion. To mitigate the impact of network congestion various techniques have been used to improve multimedia quality and one of those techniques is Active Queue Management (AQM). Access routers require a buffer to hold packets during times of congestion. A large buffer can absorb the bursty arrivals and this tends to increase the link utilizations but results in higher queuing delays. Traffic burstiness has a considerable negative impact on network performance. AQM is now considered an effective congestion control mechanism for enhancing transport protocol performance over wireless links. In order to have good link utilization it is necessary for queues to adapt to varying traffic loads. This paper considers a particular scheme which is called Adaptive AQM (AAQM) and studies its performance in the presence of feedback delays and its ability to maintain a small queue length as well as its robustness in the presence of traffic burstiness. The paper also presents a method based on the well-known Markov Modulated Poisson Process (MPP) to capture traffic burstiness and buffer occupancy. To demonstrate the generality of the presented method an analytic model is described and verified by extensive simulations of different adaptive AQM algorithms. The analysis and simulations show that AAQM outperforms the other AQMs with respect to responsiveness and robustness.

  • 50. Reider, Norbert
    et al.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    A distributed power control and mode selection algorithm for D2D communications2012Inngår i: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, s. 266-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Device-to-device (D2D) communications underlaying a cellular infrastructure has recently been proposed as a means of increasing the resource utilization, improving the user throughput and extending the battery lifetime of user equipments. In this article we propose a new distributed power control algorithm that iteratively determines the signal-to-noise-and-interference-ratio (SINR) targets in a mixed cellular and D2D environment and allocates transmit powers such that the overall power consumption is minimized subject to a sum-rate constraint. The performance of the distributed power control algorithm is benchmarked with respect to the optimal SINR target setting that we obtain using the Augmented Lagrangian Penalty Function method. The proposed scheme shows consistently near optimum performance both in a single-input-multiple-output and a multiple-input-multiple-output setting. We also propose a joint power control and mode selection algorithm that requires single cell information only and clearly outperforms the classical cellular mode operation.

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