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  • 1. A, Ahmad
    et al.
    G, Bianchi
    L, Bernstein
    G, Fodor
    G, Pujolle
    LB, Sung
    YD, Yao
    QoS support and service differentiation in wireless networks2004Inngår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 17, nr 6, s. 507-512Artikkel i tidsskrift (Fagfellevurdert)
  • 2. A, Eriksson
    et al.
    G, Fodor
    A middlebox control plane framework for wireless and mobile IP networks2004Inngår i: 2004 International Conference on Parallel Processing Workshops, 2004 (ICPP 2004 Workshops) / [ed] IEEE, New York: IEEE conference proceedings, 2004, s. 322-329Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    In wireless and mobile IP networks there is a need to support a set of functions that are related to wireless QoS provisioning, resource optimizations, mobility and security management and operator policy enforcement. These requirements have lead to the frequent usage of so called middleboxes including header/payload compressors, performance enhancement proxies, tunnel endpoints, packet filters and redirectors, QoS schedulers and others. Unfortunately, the increasing usage of these types of devices often leads to undesirable artifacts called feature interactions. In this paper we propose a framework that aims to coordinate the operation of middleboxes such that feature interactions are avoided. The three main ideas are (1) the separation of the control plane from the distributed network nodes, (2) the usage of a middlebox function independent horizontal protocol that allows mobile hosts to communicate their desired service requests to the network and (3) the usage of a vertical protocol between the network control and user planes. We present two examples in which this framework helps eliminate the risk for feature interactions. We comment on the relationship between the end-to-end principle and this framework. Finally, we discuss how future middleboxes can fit into this framework.

  • 3. Abrardo, A.
    et al.
    Belleschi, M.
    Fodor, Gábor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Moretti, M.
    A message passing approach for resource allocation in cellular OFDMA communications2012Inngår i: Global Communications Conference (GLOBECOM), 2012 IEEE, IEEE , 2012, s. 4583-4588Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper proposes a distributed and low-complexity resource allocation scheme for cellular OFDMA networks. In particular, we consider ReMP, a reweighted message passing algorithm that perturbs the standard max-sum algorithm by suitably reweighting messages. In a single-cell scenario, such a scheme allows to achieve convergence to a fixed and provably optimum point without employing any central controller. The ReMP algorithm is then adapted to a multi-cell environment. To this aim, we devise X-ReMP, a ReMP-based algorithm that combines cross-cell signaling and the regular ReMP routine that still runs within each cell. The cross-signaling among cells aids ReMP to deal with the inter-cell multiple-access interference, so that X-ReMP allows convergence to a good working point in terms of system throughput even in presence of strong inter-cell interference.

  • 4. Abrardo, A
    et al.
    Fodor, G
    Tola, B
    Network coding schemes for D2D communications based relaying for cellular coverage extension2015Inngår i: European transactions on telecommunications, ISSN 1124-318X, E-ISSN 2161-3915, Vol. -Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although network-assisted device-to-device (D2D) communications are known to improve the spectral and energy efficiency of proximal communications, the performance of cooperative D2D schemes in licenced spectrum is less understood when employed to extend the coverage of cellular networks. In this paper, we study the performance of D2D-based range extension in terms of sum rate and power efficiency when a relaying user equipment (UE) helps to improve the coverage for cell edge UEs. In our design, the relaying UE may have own traffic to transmit and receive to/from the cellular base station (BS) and can operate either in amplify-and-forward (AF) or decode-and-forward (DF) modes and can make use of either digital or analogue physical (PHY) layer network coding. In this rather general setting, we propose mode selection, resource allocation and power control schemes and study their performance by means of system simulations. We find that the performance of the DF scheme with network coding is superior both to the traditional cellular and the AF-based relaying schemes, including AF with two-slot or three-slot PHY layer network coding.

  • 5. Abrardo, A
    et al.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Tola, B.
    Network coding schemes for Device-To-Device communications based relaying for cellular coverage extension2015Inngår i: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC, 2015, s. 670-674Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we study the performance of device-To-device (D2D) based range extension in terms of sum rate and power efficiency when a relaying user equipment (UE) helps to improve the coverage for cell-edge UEs. In our design, the relaying UE has own traffic to transmit and receive to/from the cellular base station (BS) and can operate either in amplify-And-forward (AF) or decode-And-forward (DF) modes and can make use of either digital or analogue (PHY layer) network coding. In this rather general setting, we propose mode selection, resource allocation and power control schemes and study their performance by means of system simulations. We find that the performance of the DF scheme with network coding is superior both to the traditional cellular and the AF based relaying schemes, including AF with two-slot or three-slot PHY layer network coding.

  • 6.
    Abrardo, Andrea
    et al.
    Univ Siena, Dipartimento Ingn Informaz, I-53100 Siena, Italy. brardo, Andrea; Moretti, Marco.
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Moretti, Marco
    Distributed Digital and Hybrid Beamforming Schemes With MMSE-SIC Receivers for the MIMO Interference Channel2019Inngår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 68, nr 7, s. 6790-6804Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper addresses the problem of weighted sumrate maximization and mean squared error (MSE) minimization for the multiple-input multiple-output (MIMO) interference channel. Specifically, we consider a weighted minimum MSE architecture where each receiver employs successive interference cancellation (SIC) to separate the various received data streams and derive a hybrid beamforming scheme, where the transmitters operate with a number of radio frequency chains smaller than the number of antennas, particularly suited for millimeter-wave channels and 5G applications. To derive our proposed schemes, we first study the relationship between sum-rate maximization and weighted MSE minimization when using SIC receivers, assuming fully digital beamforming. Next, we consider the important-and, as it turns out, highly non-trivial-case where the transmitters employ hybrid digital/analog beamforming, developing a distributed joint hybrid precoding and SIC-based combining algorithm. Moreover, for practical implementation, we propose a signaling scheme that utilizes a common broadcast channel and facilitates the acquisition of channel state information, assuming minimal assistance from a central node such as a cellular base station. Numerical results show that both the proposed weighted MMSE-SIC schemes exhibit great advantages with respect to their linear counterparts in terms of complexity, feedback information, and performance.

  • 7.
    Abrardo, Andrea
    et al.
    Univ Siena, Dipartimento Ingn Informaz, I-53100 Siena, Italy..
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Moretti, Marco
    Univ Pisa, Dipartimento Ingn Informaz, I-50126 Pisa, Italy..
    Telek, Miklos
    Budapest Univ Technol & Econ, Dept Networked Syst & Serv, H-1117 Budapest, Hungary.;MTA BME Informat Syst Res Grp, H-1117 Budapest, Hungary..
    MMSE Receiver Design and SINR Calculation in MU-MIMO Systems With Imperfect CSI2019Inngår i: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 8, nr 1, s. 269-272Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The performance of the uplink of multiuser multiple input multiple output systems depends critically on the receiver architecture and on the quality of the acquired channel state information. A popular approach is to design linear receivers that minimize the mean squared error (MSE) of the received data symbols. Unfortunately, most of the literature does not take into account the presence of channel state information errors in the MSE minimization. In this letter we develop a linear minimum MSE (MMSE) receiver that employs the noisy instantaneous channel estimates to minimize the MSE, and highlight the dependence of the receiver performance on the pilot-to-data power ratio. By invoking the theory of random matrices, we calculate the users' signal-to-interference-plus-noise ratio as a function of the number of antennas and the pilot-to-data power ratio of all users. Numerical results indicate that this new linear receiver outperforms the classical mismatched MMSE receiver.

  • 8.
    Abrardo, Andrea
    et al.
    University of Siena, Italy.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Ericsson Research, Stockholm.
    Tola, Besmir
    University of Siena, Italy.
    Network Coding Schemes for Device-to-Device Communications Based Relaying for Cellular Coverage Extension2015Rapport (Annet vitenskapelig)
    Abstract [en]

    Although network assisted device-to-device (D2D) communications is known to improve the spectraland energy efficiency of proximal communications, its performance is less understood when employedto extend the coverage of cellular networks.In this paper, we study the performance of D2D basedrange extension in terms of sum rate and power efficiency when a relaying user equipment (UE) helps to improvethe coverage for cell-edge UEs.In our design, the relaying UE has own traffic to transmit and receive to/from the cellular base station (BS) andcan operate either in amplify-and-forward (AF) or decode-and-forward (DF) modes and can make use of either digital oranalogue (PHY layer) network coding.In this rather general setting, we propose mode selection, resource allocation and power control schemesand study their performance by means of system simulations.We find that the performance of the DF scheme with network coding is superior both to the traditional cellularand the AF based relaying schemes, including AF with two-slot or three-slot PHY layer network coding.

  • 9. AG, Valkó
    et al.
    A, Rácz
    G, Fodor
    Voice QoS in third-generation mobile systems1999Inngår i: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 17, nr 1, s. 109-123Artikkel i tidsskrift (Fagfellevurdert)
  • 10. Andras, Racz
    et al.
    Gabor, Fodor
    Zoltan, Turanyi
    Weighted fair early packet discard at an ATM switch output port1999Inngår i: INFOCOM '99. Eighteenth Annual Joint Conference of the IEEE Computer and Communications Societies. Proceedings. IEEE / [ed] IEEE, New York: IEEE , 1999, s. 1160-1168Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 11.
    Ardah, Khaled
    et al.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60440970 Fortaleza, Ceara, Brazil..
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. Ericsson Res, Radio Dept, S-16480 Stockholm, Sweden.
    Silva, Yuri C. B.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60440970 Fortaleza, Ceara, Brazil..
    Freitas, Walter C., Jr.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60440970 Fortaleza, Ceara, Brazil..
    Cavalcanti, Francisco R. P.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60440970 Fortaleza, Ceara, Brazil..
    A Novel Cell Reconfiguration Technique for Dynamic TDD Wireless Networks2018Inngår i: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 7, nr 3, s. 320-323Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In dynamic time division duplexing (DTDD) systems, the uplink (UL) and downlink (DL) resources can be configured to adapt to changing traffic conditions. Therefiwe, DTDD systems are advantageously deployed in scenarios in which the UL and DL traffic demands are asymmetric and timevarying. Unfortunately, multicell DTDD systems give rise to base station-to-base station and user equipment-to-user equipment interference, that can severely degrade the system performance. Previous works on DTDD either assumed that the UL/DL configurations are given, or they did not take into account the negative impact of multicell DTDD interference. In this letter, we propose a novel cell reconfiguration technique that considers both the prevailing traffic conditions and multicell interference levels. The proposed technique is based on an efficient solution of a mixed integer linear program, whose objective is to maximize the overall system throughput taking into account users' traffic preferences. Realistic system level simulations indicate that the proposed scheme outperforms not only the static TDD system but also other reference schemes, that disregard the DTDD specific interference effects.

  • 12.
    Ardah, Khaled
    et al.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. Ericsson Res, SE-16480 Stockholm, Sweden.
    Silva, Yuri C. B.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    Freitas, Walter C., Jr.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    Cavalcanti, Francisco R. P.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    A Unifying Design of Hybrid Beamforming Architectures Employing Phase Shifters or Switches2018Inngår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, nr 11, s. 11243-11247Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hybrid beamfiorming (BF) architectures employing phase shifters or switches reduce the number of required radio frequency chains and the power consumption of base stations that employ a large number of antennas. Due to the inherent tradeoff between the number of radio frequency chains, the complexity of the employed analog and digital BF algorithms and the achieved spectral and energy efficiency, designing hybrid BF architectures is a complex task. To deal with this ormplexity, we propose a unifying design that is applicable to architectures employing either phase shifters or switches. In our design, the analog part (!if the hybrid BF architecture maximizes the capacity of the equivalent channel, while the digital part is updated using the well-known block diagonalizat' approach. We then employ the proposed joint analog-digital beamforming algorithm on lour recently proposed hybrid architectures and compare their performance in terms of spectral and energy efficiency, and find that the proposed analog-digital BF algorithm outperforms previously proposed schemes. We also find that phase shifterbased architectures achieve high spectral efficiency, whereas switching-based architectures can boost energy efficiency with increasing number of base station antennas.

  • 13.
    Ardah, Khaled
    et al.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, Fortaleza, Ceara, Brazil..
    Silva, Yuri C. B.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, Fortaleza, Ceara, Brazil..
    Freitas, Walter C., Jr.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, Fortaleza, Ceara, Brazil..
    Cavalcanti, Francisco R. P.
    Univ Fed Ceara, Wireless Telecom Res Grp GTEL, Fortaleza, Ceara, Brazil..
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    An ADMM Approach to Distributed Coordinated Beamforming in Dynamic TDD Networks2017Inngår i: 2017 IEEE 7TH INTERNATIONAL WORKSHOP ON COMPUTATIONAL ADVANCES IN MULTI-SENSOR ADAPTIVE PROCESSING (CAMSAP), IEEE , 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider a dynamic time division duplexing wireless network and propose a distributed coordinated beamforming algorithm based on Alternating Direction Method of Multipliers (ADMM) technique assuming the availability of perfect channel state information. Our design objective is to minimize the sum transmit power at the base stations subject to minimum signal-to-interference-plus-noise ratio (SINR) constraints for downlink mobile stations and a maximum interference power threshold for uplink mobile stations. First, we propose a centralized algorithm based on the relaxed Semidefinite Programming (SDP) technique. To obtain the beamforming solution in a distributed way, we further propose a distributed coordinated beamforming algorithm using the ADMM technique. Detailed simulation results are presented to examine the effectiveness of the proposed algorithms. It is shown that the proposed algorithm achieves better performance in terms of the design objective and converges faster than the reference algorithm based on primal decomposition.

  • 14. Astely, D
    et al.
    Dahlman, E
    Fodor, Gabor
    Parkvall, S
    Sachs, J
    LTE release 12 and beyond2013Inngår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 51, nr 7, s. 154-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As the specification of Release 11 of the LTE standards is approaching its completion, 3GPP is gradually moving its focus toward the next major step in the evolution of LTE. The drivers of the LTE evolution include the increasing demand for mobile broadband services and traffic volumes as well as emerging usage scenarios involving short-range and machine-type communications. In this article we provide an overview of the key technology areas/components that are currently considered by 3GPP for Rel-12, including support for further enhanced local area access by tight interaction between the wide area and local area layers, signaling solutions for wireless local area network integration, multi-antenna enhancements, improved support for massive MTC, and direct device-to-device communications.

  • 15. AT, Andersen
    et al.
    S, Blaabjerg
    Fodor, G
    M, Telek
    A partially-blocking queueing system with CBR/VBR and ABR/UBR arrival streams2002Inngår i: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 19, nr 1, s. 75-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper we consider an ATM transmission link., to which CBR or VBR and ABR or UBR calls arrive according to independent Poisson processes. CBR/VBR calls (characterized by their equivalent bandwidth) are blocked and leave the system if the available link capacity is less than required at the time of arrival. ABR/UBR calls, however, accept partial blocking, meaning that they may enter service even if the available capacity is less than the specified required peak bandwidth, but greater than the so called minimal accepted bandwidth. Partially blocked ABR/UBR calls instead experience longer service time, since smaller given bandwidth entails proportionally longer time spent in the system, as first suggested in [3] and analyzed in details herein. Throughout the life time of an ABR/UBR connection, its bandwidth consumption fluctuates in accordance with the current load on the link but always at the highest possible value up to their peak bandwidth (greedy sources). Additionally, if this minimal accepted bandwidth is unavailable at the time of arrival, ABR/UBR calls are allowed to wait in a finite queue. This system is modeled by a Continuous Time Markov Chain (CTMC) and the CBR/VBR and ABR/UBR blocking probabilities and the mean ABR/UBR waiting- and service times are derived.

  • 16.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Ericsson Research.
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Fast-Lipschitz Power Control and User-Frequency Assignment in Full-Duplex Cellular Networks2017Inngår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, nr 10, s. 6672-6687Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In cellular networks, the three-node full-duplex transmission mode has the po-tential to increase spectral efficiency without requiring full-duplex capability ofusers. Consequently, three-node full-duplex in cellular networks must deal with self-interference and user-to-user interference, which can be managed by power controland user-frequency assignment techniques. This paper investigates the problem ofmaximizing the sum spectral efficiency by jointly determining the transmit powersin a distributed fashion, and assigning users to frequency channels. The problem is for-mulated as a mixed-integer nonlinear problem, which is shown to be non-deterministicpolynomial-time hard. We investigate a close-to-optimal solution approach by dividingthe joint problem into a power control problem and an assignment problem. The powercontrol problem is solved by Fast-Lipschitz optimization, while a greedy solution withguaranteed performance is developed for the assignment problem. Numerical resultsindicate that compared with the half-duplex mode, both spectral and energy efficienciesof the system are increased by the proposed algorithm. Moreover, results show that thepower control and assignment solutions have important, but opposite roles in scenarioswith low or high self-interference cancellation. When the self-interference cancellationis high, user-frequency assignment is more important than power control, while powercontrol is essential at low self-interference cancellation.

  • 17.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Ericsson Research.
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    On the Spectral Efficiency and Fairness in Full-Duplex Cellular Networks2017Inngår i: 2017 IEEE International Conference on Communications (ICC), Paris: Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 1-6, artikkel-id 7996391Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To increase the spectral efficiency of wireless networks without requiring full-duplex capability of user devices, a potential solution is the recently proposed three-node full-duplex mode. To realize this potential, networks employing three-node full-duplex transmissions must deal with self-interference and user-to-user interference, which can be managed by frequency channel and power allocation techniques. Whereas previous works investigated either spectral efficient or fair mechanisms, a scheme that balances these two metrics among users is investigated in this paper. This balancing scheme is based on a new solution method of the multi-objective optimization problem to maximize the weighted sum of the per-user spectral efficiency and the minimum spectral efficiency among users. The mixed integer non-linear nature of this problem is dealt by Lagrangian duality. Based on the proposed solution approach, a low-complexity centralized algorithm is developed, which relies on large scale fading measurements that can be advantageously implemented at the base station. Numerical results indicate that the proposed algorithm increases the spectral efficiency and fairness among users without the need of weighting the spectral efficiency. An important conclusion is that managing user-to-user interference by resource assignment and power control is crucial for ensuring spectral efficient and fair operation of full-duplex networks.

  • 18.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Ericsson Research.
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Spectral Efficient and Fair User Pairing for Full-Duplex Communication in Cellular Networks2016Inngår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 15, nr 11, s. 7578-7593Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    —A promising new transmission mode in cellular networks is the three-node full-duplex mode, which involves a base station with full-duplex capability and two half-duplex user transmissions on the same frequency channel for uplink and downlink. The three-node full-duplex mode can increase spectral efficiency, especially in the low transmit power regime, without requiring full-duplex capability at user devices. However, when a large set of users is scheduled in this mode, self-interference at the base station and user-to-user interference can substantially hinder the potential gains of full-duplex communications. This paper investigates the problem of grouping users to pairs and assigning frequency channels to each pair in a spectral efficient and fair manner. Specifically, the joint problem of user uplink/downlink frequency channel pairing and power allocation is formulated as a mixed integer nonlinear problem that is solved by a novel joint fairness assignment maximization algorithm. Realistic system level simulations indicate that the spectral efficiency of the users having the lowest spectral efficiency is increased by the proposed algorithm, while a high ratio of connected users in different loads and self-interference levels is maintained.

  • 19.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Ghauch, Hadi
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    How to Split UL/DL Antennas in Full-DuplexCellular Networks2018Inngår i: IEEE International Conference on Communication (ICC’18): ThirdWorkshop on Full-Duplex Communications for Future Wireless Networks, Kansas City, MO, USA: IEEE Communications Society, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To further improve the potential of full-duplex com-munications, networks may employ multiple antennas at thebase station or user equipment. To this end, networks thatemploy current radios usually deal with self-interference andmulti-user interference by beamforming techniques. Althoughprevious works investigated beamforming design to improvespectral efficiency, the fundamental question of how to split theantennas at a base station between uplink and downlink infull-duplex networks has not been investigated rigorously. Thispaper addresses this question by posing antenna splitting as abinary nonlinear optimization problem to minimize the sum meansquared error of the received data symbols. It is shown that thisis an NP-hard problem. This combinatorial problem is dealt withby equivalent formulations, iterative convex approximations, anda binary relaxation. The proposed algorithm is guaranteed toconverge to a stationary solution of the relaxed problem with muchsmaller complexity than exhaustive search. Numerical resultsindicate that the proposed solution is close to the optimal in bothhigh and low self-interference capable scenarios, while the usuallyassumed antenna splitting is far from optimal. For large numberof antennas, a simple antenna splitting is close to the proposedsolution. This reveals that the importance of antenna splittingdiminishes with the number of antennas.

  • 20.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Ghauch, Hadi
    Fodor, Gabor
    Skoglund, Mikael
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Smart Antenna Assignment is Essential in Full-Duplex Communications2019Inngår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Full-duplex communications have the potential to almost double the spectralefficiency. To realize such a potentiality, the signal separation at base station’s antennasplays an essential role. This paper addresses the fundamentals of such separationby proposing a new smart antenna architecture that allows every antenna to beeither shared or separated between uplink and downlink transmissions. The benefitsof such architecture are investigated by an assignment problem to optimally assignantennas, beamforming and power to maximize the weighted sum spectral efficiency.We propose a near-to-optimal solution using block coordinate descent that divides theproblem into assignment problems, which are NP-hard, a beamforming and powerallocation problems. The optimal solutions for the beamforming and power allocationare established while near-to-optimal solutions to the assignment problems are derivedby semidefinite relaxation. Numerical results indicate that the proposed solution isclose to the optimum, and it maintains a similar performance for high and low residualself-interference powers. With respect to the usually assumed antenna separationtechnique and half-duplex transmission, the sum spectral efficiency gains increase withthe number of antennas. We conclude that our proposed smart antenna assignment forsignal separation is essential to realize the benefits of multiple antenna full-duplexcommunications.

  • 21.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Sabharwal, Ashutosh
    Rice University.
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Low Resolution Phase Shifters Suffice for Full-Duplex mmWave Communications2019Inngår i: IEEE International Conference on Communications: Workshop on Full-Duplex Communications for Future Wireless Networks, Shangai, China: IEEE Communications Society, 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Full-duplex base-stations with half-duplex nodes,allowing simultaneous uplink and downlink from different nodes,have the potential to double the spectrum efficiency withoutadding additional complexity at mobile nodes. Hybrid beam-forming is commonly used in millimeter-wave systems for itsimplementation efficiency. An important element of hybrid beam-forming is quantized phase shifters. In this paper, we ask iflow-resolution phase shifters suffice for beamforming-based full-duplex millimeter-wave systems. We formulate the problem ofjoint design for both self-interference suppression and downlinkbeamforming as an optimization problem, which we solve usingpenalty dual decomposition to obtain a near-optimal solution.Numerical results indicate that low-resolution phase shifters canperform close to systems that use infinite phase shifter resolution,and that even a single quantization bit outperforms half-duplextransmissions in both low and high residual self-interferencescenarios.

  • 22.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Skouroumounis, Christodoulos
    University of Cyprus.
    Krikidis, Ioannis
    University of Cyprus.
    Fodor, Gabor
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Energy Efficient Full-Duplex Networks2019Inngår i: Green Communications for Energy-EfficientWireless Systems and Networks / [ed] A. Zappone, J. Yang, J. S. Thompson, H. Suraweera, The Institution of Engineering and Technology (IET) , 2019Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    As the specifications of the 5th generation of cellular networks mature, the deployment phase is starting up. Hence, peaks of data rates in the order of tens of Gbit/s as well as more energy efficient deployments are expected. Nevertheless, the quick development of new applications and services encourage the research community to look beyond 5G and explore new technological components. Indeed, to meet the increasing demand for mobile broadband as well as internet of things type of services, the research and standardization communities are currently investigating novel physical and medium access layer technologies, including further virtualization of networks, the use of the lower Terahertz bands, even higher cell densification, and full-duplex (FD) communications.

     

    FD has been proposed as one of the enabling technologies to increase the spectral efficiency of conventional wireless transmission modes, by overcoming our prior understanding that it is not possible for radios to transmit and receive simultaneously on the same time-frequency resource. Due to this, we can also refer to FD communications as in-band FD. In-band FD transceivers have the potential of improving the attainable spectral efficiency of traditional wireless networks operating with half-duplex (HD) transceivers by a factor close to two. In addition to the spectral efficiency gains, full-duplex can provide gains in the medium access control layer, in which problems such as the hidden/exposed nodes and collision detection can be mitigated and the energy consumption can be reduced.

     

    Until recently, in-band FD was not considered as a solution for wireless networks due to the inherent interference created from the transmitter to its own receiver, the so-called self-interference (SI). However, recent advancements in antenna and analog/digital interference cancellation techniques demonstrate FD transmissions as a viable alternative to traditional HD transmissions. Given the recent architectural progression of 5G towards smaller cells, higher densification, higher number of antennas and utilizing the millimeter wave (mmWave) band, the integration of FD communications into such scenarios is appealing. In-band FD communications are suited for short range communication, and although the SI remains a challenge, the use of multiple antennas and the transmission in the mmWave band are allies that help to mitigate the SI in the spatial domain and provide even more gains for spectral and energy efficiency. To achieve the spectral and energy efficiency gains, it is important to understand the challenges and solutions, which can be roughly divided into resource allocation, protocol design, hardware design and energy harvesting. Hence, FD communications appears as an important technology component to improve the spectral and energy efficiency of current communication systems and help to meet the goals of 5G and beyond.

     

    The chapter starts with an overview of FD communications, including its challenges and solutions. Next, a comprehensive literature review of energy efficiency in FD communications is presented along with the key solutions to improve energy efficiency. Finally, we evaluate the key aspects of energy efficiency in FD communications for two scenarios: single-cell with multiple users in a pico-cell scenario, and a system level evaluation with macro- and small-cells with multiple users.

  • 23.
    Barros da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Ericsson Research.
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Distributed Spectral Efficiency Maximization in Full-Duplex Cellular Networks2016Inngår i: IEEE International Conference on Communication (ICC16): Workshop on Novel Medium Access and Resource Allocation for 5G Networks, Kuala Lumpur: IEEE Communications Society, 2016, s. 80-86, artikkel-id 7503768Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Three-node full-duplex is a promising new transmission mode between a full-duplex capable wireless node and two other wireless nodes that use half-duplex transmission and reception respectively. Although three-node full-duplex transmissions can increase the spectral efficiency without requiring full-duplex capability of user devices, inter-node interference - in addition to the inherent self-interference - can severely degrade the performance. Therefore, as methods that provide effective self-interference mitigation evolve, the management of inter-node interference is becoming increasingly important. This paper considers a cellular system in which a full-duplex capable base station serves a set of half-duplex capable users. As the spectral efficiencies achieved by the uplink and downlink transmissions are inherently intertwined, the objective is to device channel assignment and power control algorithms that maximize the weighted sum of the uplink-downlink transmissions. To this end a distributed auction based channel assignment algorithm is proposed, in which the scheduled uplink users and the base station jointly determine the set of downlink users for full-duplex transmission. Realistic system simulations indicate that the spectral efficiency can be up to 89% better than using the traditional half-duplex mode. Furthermore, when the self-interference cancelling level is high, the impact of the user-to-user interference is severe unless properly managed.

  • 24.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Fodor, Gábor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Ericsson Research.
    A Binary Power Control Scheme for D2D Communications2015Inngår i: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 4, nr 6, s. 669-672Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Binary power control (BPC) is known to maximize the capacity of a two-cell interference limited system and performs near optimally for larger systems. However, when device-to-device (D2D) communication underlaying the cellular layer is supported, an objective function that considers the power consumption is more suitable. We find that BPC remains optimal for D2D communications when the weight of the overall power consumption in the utility function is bounded. Building on this insight, we propose a simple near-optimal extended BPC scheme and compare its performance with a recently proposed utility optimal iterative scheme using a realistic multicell simulator. Our results indicate that a near optimal D2D performance can be achieved without lengthy iterations or complex signaling mechanisms.

  • 25.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik. Royal Inst Technol, KTH, Stockholm, Sweden..
    Ghauch, Hadi
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    How to Split UL/DL Antennas in Full-Duplex Cellular Networks2018Inngår i: 2018 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS), IEEE, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To further improve the potential of full-duplex communications, networks may employ multiple antennas at the base station or user equipment. To this end, networks that employ current radios usually deal with self-interference and multi-user interference by beamforming techniques. Although previous works investigated beamforming design to improve spectral efficiency, the fundamental question of how to split the antennas at a base station between uplink and downlink in full-duplex networks has not been investigated rigorously. This paper addresses this question by posing antenna splitting as a binary nonlinear optimization problem to minimize the sum mean squared error of the received data symbols. It is shown that this is an NP-hard problem. This combinatorial problem is dealt with by equivalent formulations, iterative convex approximations, and a binary relaxation. The proposed algorithm is guaranteed to converge to a stationary solution of the relaxed problem with much smaller complexity than exhaustive search. Numerical results indicate that the proposed solution is close to the optimal in both high and low self-interference capable scenarios, while the usually assumed antenna splitting is far from optimal. For large number of antennas, a simple antenna splitting is close to the proposed solution. This reveals that the importance of antenna splitting diminishes with the number of antennas.

  • 26.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Sabharwal, Ashutosh
    Fodor, Gabor
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    1-bit Phase Shifters Suffice for Large-Antenna Full-Duplex mmWave Communications2019Inngår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Millimeter-wave using large-antenna arrays is a key technological component forthe future cellular systems, where it is expected that hybrid beamforming along withquantized phase shifters will be used due to their implementation and cost efficiency.In this paper, we investigate the efficacy of full-duplex mmWave communicationwith hybrid beamforming using low-resolution phase shifters, without any analogself-interference cancellation. We formulate the problem of joint self-interferencesuppression and downlink beamforming as a mixed-integer nonconvex joint opti-mization problem. We propose LowRes, a near-to-optimal solution using penaltydual decomposition. Numerical results indicate that LowRes using low-resolutionphase shifters perform within 3% of the optimal solution that uses infinite phaseshifter resolution. Moreover, even a single quantization bit outperforms half-duplextransmissions, respectively by 29% and 10% for both low and high residual self-interference scenarios, and for a wide range of practical antenna to radio-chain ratios.Thus, we conclude that 1-bit phase shifters suffice for full-duplex millimeter-wavecommunications, without requiring any additional new analog hardware.

  • 27.
    Barros da Silva Jr., José Mairton
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Sabharwal, Ashutosh
    Rice Univ, Houston, TX USA..
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. Ericsson Res, Kista, Sweden..
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Low Resolution Phase Shifters Suffice for Full-Duplex mmWave Communications2019Inngår i: 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS), IEEE , 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Full-duplex base-stations with half-duplex nodes, allowing simultaneous uplink and downlink from different nodes, have the potential to double the spectrum efficiency without adding additional complexity at mobile nodes. Hybrid beam forming is commonly used in millimeter wave systems for its implementation efficiency. An important element of hybrid beam-forming is quantized phase shifters. In this paper, we ask if low-resolution phase shifters suffice for beamforming-based full-duplex millimeter wave systems. We formulate the problem of joint design for both self-interference suppression and downlink beamforming as an optimization problem, which we solve using penalty dual decomposition to obtain a near-optimal solution. Numerical results indicate that low-resolution phase shifters can perform close to systems that use infinite phase shifter resolution, and that even a single quantization bit outperforms half-duplex transmissions in both low and high residual self-interference scenarios.

  • 28. Belleschi, M
    et al.
    Fodor, G
    Abrardo, A
    Performance analysis of a distributed resource allocation scheme for D2D communications2011Inngår i: 2011 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE (GLOBECOM 2011): 54th Annual IEEE Global Telecommunications Conference (GLOBECOM) / [ed] IEEE, New York: IEEE conference proceedings, 2011, s. 358-362Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Device-to-device (D2D) communications underlaying a cellular infrastructure has recently been proposed as a means of increasing the cellular capacity, improving the user throughput and extending the battery lifetime of user equipments by facilitating the reuse of spectrum resources between D2D and cellular links. In network assisted D2D communications, when two devices are in the proximity of each other, the network can not only help the devices to set the appropriate transmit power and schedule time and frequency resources but also to determine whether communication should take place via the direct D2D link (D2D mode) or via the cellular base station (cellular mode). In this paper we formulate the joint mode selection, scheduling and power control task as an optimization problem that we first solve assuming the availability of a central entity. We also propose a distributed suboptimal joint mode selection and resource allocation scheme that we benchmark with respect to the centralized optimal solution. We find that the distributed scheme performs close to the optimal scheme both in terms of resource efficiency and user fairness.

  • 29.
    Belleschi, Marco
    et al.
    Ericsson AB, Sweden.
    Fodor, Gabor
    Ericsson AB, Sweden.
    Della Penda, Demia
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Pradini, Aidilla
    Ericsson AB, Sweden.
    Johansson, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Abrardo, Andrea
    University of Siena, Italy.
    Benchmarking Practical RRM Algorithms for D2D Communications in LTE Advanced2014Inngår i: Wireless personal communications, ISSN 0929-6212, E-ISSN 1572-834X, Vol. 82, nr 2, s. 883-910Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Device-to-device (D2D) communication integrated into cellular networks is an advanced tool to take advantage of the proximity of devices and allow for reusing cellular resources and thereby to increase the user bitrates and the system capacity. However, the introduction of D2D in legacy long term evolution (LTE) cellular spectrum requires to revisit and modify the existing radio resource management and power control (PC) techniques in order to fully realize the potential of the proximity and reuse gains and to limit the interference to the cellular layer. In this paper, we examine the performance of the legacy LTE PC tool box and benchmark it against an utility optimal iterative scheme. We find that the open loop PC scheme of LTE performs well for cellular users both in terms of the used transmit power levels and the achieved signal-to-interference-and-noise-ratio distribution. However, the performance of the D2D users as well as the overall system throughput can be boosted by the utility optimal scheme, by taking better advantage of both the proximity and the reuse gains. Therefore, in this paper we propose a hybrid PC scheme, in which cellular users employ the legacy LTE open loop PC, while D2D users exploits the utility optimizing distributed PC scheme. We also recognize that the hybrid scheme is not only nearly optimal, and can balance between spectral and energy efficiency, but it also allows for a distributed implementation at the D2D users, while preserving the LTE PC scheme for the cellular users.

  • 30. Blaabjerg, S
    et al.
    Fodor, G
    Andersen, A T
    Telek, M
    A partially blocking-queueing system with CBR/VBR and ABR/UBR arrival streems2002Konferansepaper (Fagfellevurdert)
  • 31. Boccardi, Federico
    et al.
    Shokri-Ghadikolaei, Hossein
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Ericsson Research, United States.
    Erkip, Elza
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Kountouris, Marios
    Popovski, Petar
    Zorzi, Michele
    Spectrum Pooling in MmWave Networks: Opportunities, Challenges, and Enablers2016Inngår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 54, nr 11, s. 33-39Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Motivated by the specific characteristics of mmWave technologies, we discuss the possibility of an authorization regime that allows spectrum sharing between multiple operators, also referred to as spectrum pooling. In particular, considering user rate as the performance measure, we assess the benefit of coordination among networks of different operators, study the impact of beamforming at both base stations and user terminals, and analyze the pooling performance at different frequency carriers. We also discuss the enabling spectrum mechanisms, architectures, and protocols required to make spectrum pooling work in real networks. Our initial results show that, from a technical perspective, spectrum pooling at mmWave has the potential to use the resources more efficiently than traditional exclusive spectrum allocation to a single operator. However, further studies are needed in order to reach a thorough understanding of this matter, and we hope that this article will help stimulate further research in this area.

  • 32.
    Cavalcante, Eduardo de Olivindo
    et al.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. Ericsson Res, SE-16480 Stockholm, Sweden.
    Silva, Yuri C. B.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    Freitas Jr, Walter C.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60020181 Fortaleza, Ceara, Brazil..
    Distributed Beamforming in Dynamic TDD MIMO Networks With BS to BS Interference Constraints2018Inngår i: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 7, nr 5, s. 788-791Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This letter proposes distributed beamforming as a means of reducing interference in dynamic time division duplexing multiple input multiple output networks. Specifically, we formulate an optimization task, whose objective is to minimize the base station (BS) transmit power, while satisfying a predefined signal-to-interference-plus-noise ratio threshold for each downlink user equipment and keeping the BS to BS interference power below a tolerable level. An iterative decentralized solution requiring reduced signaling load based on primal decomposition is proposed. This decentralized algorithm is shown to iterate towards the centralized solution, while feasible but suboptimal solutions can be obtained at any iteration.

  • 33. Cinkler, T
    et al.
    Fodor, G
    Ast, L
    Rácz, S
    End-to-End Blocking Probability Approximations for Resource Management in Multi-Rate Loss Networks1995Konferansepaper (Fagfellevurdert)
  • 34. Cinkler, T
    et al.
    Laborczi, P
    Pióro, M
    Malicskó, G
    Fodor, G
    Szentesi, Á
    Algorithms for Path and Bandwidth Allocation for Elastic Traffic under various Fairness Constraints2002Inngår i: Proceedings of the 2nd Polish-German Teletraffic Symposium PGTS 2002; 9th Polish Teletraffic Symposium, Gdansk: IFIP , 2002, s. 1-5Konferansepaper (Annet vitenskapelig)
  • 35. D, Mariz
    et al.
    I, Cananéa
    D, Sadok
    G, Fodor
    Simulative analysis of access selection algorithms for multi-access networks2006Inngår i: 2006 International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM'06) / [ed] IEEE, New York: IEEE conference proceedings, 2006, s. 219-227Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    It is expected that future wireless systems will consist of several distinct radio access technologies (including WCDMA/HSDPA, GSM/EDGE/GPRS, WLAN and others) forming a multi-access system that offers advanced voice and multimedia services. Previous works have shown that the combined capacity region of such systems depend on the service allocation policy that assigns user sessions to the available subsystems. The currently available service allocation policies typically operate off-line implying that the actual service mix is assumed to be known prior to the service allocation taking place. In this paper we consider the on-line problem according to which sessions arrive one after the other and no assumptions on the service mix can be made. We adopt four on-line bin-packing algorithms to the multi-access environment and study their performance by means of simulation in terms of the class-wise blocking probability and throughput. We find that the algorithm termed Less Voice provides the best performance in terms of the blocking probabilities and imposes the least slow down for elastic sessions

  • 36. Dimou, Konstantinos
    et al.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES). Ericsson Research.
    Cavalcanti, Francisco Rodrigo P.
    MACIEL, Tarcísío
    Dynamic Resource Selection to Reduce Interference That Results From Direct Device-to-Device Communications2013Patent (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Systems and methods are disclosed for selecting resources for direct device to device (D2D) communications in a cellular communication, network. in one embodiment, a downlink resource is selected as a resource tor a direct D2D communication link between a first wireless device and a second wireless device if a base station serving each of the first and second wireless devices is equipped with an interference cancellation receiver and both the first and second wireless devices are less than a predefined threshold radio distance from their serving base station. An uplink resource is selected as a resource for the direct D2D communication link if the base station serving each of the first and second wireless devices is equipped with an interference cancellation receiver and at least one of the first and second wireless devices is more than the predefined threshold radio distance from its serving base station.

  • 37. Dimou, Konstantinos
    et al.
    Simonsson, Arne
    Müller, Walter
    Fodor, Gabor
    Furuskär, Anders
    Intercell interference coordination for radio resource control2008Patent (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Embodiments described herein relate generally to wireless communication systems, and more particularly, to intercell interference coordination for radio resource control.

  • 38. Eriksson, Anders
    et al.
    Fodor, Gabor
    Flow control packet mobile communication2004Patent (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    A method for controlling flow of data packets sent roaming user on a plane usuariobasado IP, said method comprising the steps of: a. control individual flows of data packets from mobile user sent on plane usuariobasado IP from a plane common control based on IP provided with agents (15) midcom in queel common control plane based on IP is spaced from the plane IP-based user, dichocontrol being provided by: b. each packet flow data mobile users register their identity in each middlebox (13, 14) said flow is along a path from an originating terminal to a dedestino terminal in the user plane IP-based c . in response, each middlebox user plane IP-based registers (16) itself and wings identities of packet flows data roaming user it runs in the plane of usuariobasado IP in an agent ( 15) midcom in the common control plane based on IP with which éstoscomunican using a signaling protocol to support extended midcom delflujo registration and control data packets phones, user d. agent midcom, now aware of the flows of data packets of móvilesregistrados user, which signals (17) control commands to the middleboxes that were recorded, belonging dichasórdenes the management of packet flows mobile data user delplano middleboxes the respective user based on IP.

  • 39. Ernst, Nordstrom
    et al.
    Soren, Blaabjerg
    Gabor, Fodor
    Admission control of CBR/VBR and ABR/UBR call arrival streams: A Markov decision approach1997Inngår i: Proceedings of IEEE ATM Workshop 1997 / [ed] IEEE, New York: IEEE , 1997, s. 113-122Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 40.
    Fallgren, Mikael
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Oddsdóttir, H. Æ
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Fodor, G.
    An optimization approach to joint cell and power allocation in multicell networks2011Inngår i: IEEE Int Conf Commun, 2011, s. 5963591-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Since the seminal paper by Knopp and Humblet that showed that the system throughput of a single cell system is maximized if only one terminal transmits at a time, there has been a large interest in opportunistic communications and its relation to various fairness measures. On the other hand, in multicell systems there is a need to allocate transmission power such that some overall utility function is maximized typically under fairness constraints. Furthermore, in multicell systems the degree of resource allocation freedom includes the serving cell selection that allows for load balancing and thereby the efficient use of radio resources. In this paper we formulate the joint serving cell selection (link selection) and power allocation problem as an optimization task whose purpose is to maximize either the minimum user throughput or the multicell sum throughput. Both the max-min and the max-throughput problems are non-polynomial hard and we therefore propose heuristic solution approaches. We present numerical results that give new and valuable insights into the trade off between fair and sum throughput optimal joint resource allocation strategies.

  • 41. Fodor, G
    et al.
    Barta, P
    Marquetant, A
    Rácz, A
    Henk, T
    QoS Routing Strategies in Broadband Multiservice Networks1998Inngår i: / [ed] IEEE, null, 1998, s. 184-193Konferansepaper (Fagfellevurdert)
  • 42. Fodor, G
    et al.
    Dahlman, E
    Parkvall, S
    Mildh, G
    Reider, N
    Miklos, G
    Turanyi, Z
    Design Aspects of Network Assisted Device-to-Device Communications2012Inngår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 50, nr 3, s. 170-177Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Device-to-device (D2D) communications underlaying a cellular infrastructure has been proposed as a means of taking advantage of the physical proximity of communicating devices, increasing resource utilization, and improving cellular coverage. Relative to the traditional cellular methods, there is a need to design new peer discovery methods, physical layer procedures, and radio resource management algorithms that help realize the potential advantages of D2D communications. In this article we use the 3GPP Long Term Evolution system as a baseline for D2D design, review some of the key design challenges, and propose solution approaches that allow cellular devices and D2D pairs to share spectrum resources and thereby increase the spectrum and energy efficiency of traditional cellular networks. Simulation results illustrate the viability of the proposed design.

  • 43. Fodor, G
    et al.
    Gaál, B
    Haraszti, Zs
    Henk, T
    Ziaja, Zs
    Dahlquist, I
    A Flexible Simulation Platform for ATM Networks1994Inngår i: / [ed] Kayran, Ali L; Lehmann, Axel; Ören, Tuncer I, 1994, s. 79-81Konferansepaper (Fagfellevurdert)
  • 44. Fodor, G
    et al.
    Marosits, T
    Molnár, S
    A General Traffic Control Framework in ATM Networks1996Konferansepaper (Fagfellevurdert)
  • 45. Fodor, G
    et al.
    Olin, B
    Persson, F
    Roobol, C
    Williams, B
    Differentiated and Integrated Services for IP Applications over UMTS2003Inngår i: Wireless IP and Building the Mobile Internet / [ed] Dixit, Sudhir; Prasad, Ramjee, London: London , 2003, s. 133-160Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 46.
    Fodor, Gabor
    Ericsson Research.
    Channel Estimation and Receiver Design in Single- and Multiuser Multiantenna Systems: Dissertation Submitted for the Degree of Doctor of the Hungarian Academy of Sciences2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    As an engineer and researcher, I have been dealing with the research, standardization and industrial-ization of wireless communication systems since the late 90’s. Specifically, I have been witnessing andcontributing to the evolution of the 3rd, 4th and currently to the 5th generation of cellular networks.The impact of this evolution on the society, public administration, businesses and individuals has beenprofound and played a key role in defining the information age and shaping the fully connected societies.Indeed, the technology footprint of cellular networks has lead to unprecedented economies of scale,which, in turn resulted in a rapid growth of technology solutions that enable them to operate with highspectral and energy efficiency in a great number of spectrum bands.My contributions to the advances of cellular technologies lie in the fields of radio resource managementand signal processing for multi-antenna systems, and specifically in the areas of channel estimation andreceiver design. In particular, my contributions as a researcher are threefold: (i) conducting research forthe purpose of proposing channel estimation and receiver designs that are superior to their state-of-the-artcounterparts, (ii) identifying the necessary changes in communication standards that ensure the inter-operability of such novel designs and (iii) developing suitable methodology for the performance analysisof the proposed channel estimation and receiver techniques. The results of these efforts include researchpapers in internationally recognized journals and book chapters, communication standards specificallydeveloped for the inter-operability of cellular systems and more than 40 internationally granted patentsthat are deployed in cellular systems around the world.In this thesis, I develop methodology and techniques to develop receiver algorithms that are optimalin terms of minimizing the mean squared error of the received data symbols in the presence of theestimation errors of the prevailing wireless channels through which communication takes place. Theproposed methodology and techniques enable me to prove that the state-of-the-art receiver structures aresuboptimal in the presence of wireless channel estimation errors, while the proposed receivers are optimalin terms of minimizing the symbol errors at multi-antenna receivers. I also developed methodology thatenables the exact analysis of the symbol errors as functions of the resources used for obtaining channelestimates at the wireless receiver and transmitting data through the wireless channel.These methods have lead to channel estimation techniques and receiver algorithms that significantlyimprove the spectral and energy efficiency of multi-antenna cellular systems, and simplify the designof receiver algorithms when the number of deployed antennas at cellular infrastructure nodes increasesover time.

  • 47. Fodor, Gabor
    Method and apparatus for allocating radio resources in a mobile radio network2011Patent (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    A method and apparatus for allocating radio resources to an elastic session in a cell in a CDMA network is presented. The method comprises allocating, to the elastic session, a radio resource share corresponding to a reduced transmission rate wherein the reduction in transmission rate corresponds to a peak transmission rate of the elastic session being slowed down by a first slowdown rate. The first slow down rate is determined in dependency of the transmission rate requirements of the ongoing sessions in the cell in a manner so that the radio resource share allocated is not lower than a radio resource share corresponding to the maximum transmission rate if a total amount of resources available for allocation to ongoing sessions in the cell is sufficient for all ongoing sessions to transmit at a respective peak transmission rate.

  • 48.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Ericsson Research.
    Method and Arrangement for Adjusting Signal-to-Interference-Plus-Noise-Ratio In a Device-to-Device Communication2013Patent (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    A method in a first wireless device for adjusting Signal-to-Interference-plus-Noise-Ratio, SINR, target and a transmit rate is provided. The first wireless device is configured to transmit data to a second wireless device over a Device-to-Device, D2D, link. The first wireless device receives a report on a control channel from the second wireless device. The report comprises a measurement of SINR on said control channel and/or a data channel transmitted by the first device. The first wireless device adjusts a transmit power for the control channel and/or the data channel based on the reported measurement of the SINR on said control channel and/or data channel transmitted by the first device. The first wireless device then adjusts a SINR target and a transmit rate based on the adjusted transmit power. The SINR target and transmit rate are to be used when transmitting on the data channel over the D2D link to the second wireless device.

  • 49. Fodor, Gabor
    Method and arrangement in a communication system2014Patent (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    A first user terminal and method of operating the first user terminal so as to provide location information associated with the first user terminal to a second user terminal are disclosed. The first user terminal and the second user terminal are comprised within a wireless communication system, which wireless communication system further comprises a plurality of radio base stations of which a first one of the plurality of radio base stations is serving the first user terminal. A signal is received from one of the radio base stations comprising the absolute geographical coordinates corresponding to the location of that radio base station. Pilot signal measurements are performed on the received signal. The absolute geographical coordinates corresponding to the location of the first user terminal are determined based on the performed pilot signal measurements and the received absolute geographical coordinates of the radio base station. The determined absolute geographical coordinates are transmitted to the second user terminal.

  • 50.
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. Ericsson Res, Stockholm, Swede.
    Mode selection schemes for unicasting device-to-device communications supported by network coding2018Inngår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 31, nr 11, artikkel-id e3594Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Device-to-device (D2D) communication in a cellular spectrum increases the spectral and energy efficiency of local communication sessions, while also taking advantage of accessing licensed spectrum and higher transmit power levels than when using unlicensed bands. To realize the potential benefits of D2D communications, appropriate mode selection algorithms that select between the cellular and D2D communication modes must be designed. On the other hand, physical-layer network coding (NWC) at a cellular base stationwhich can be used without D2D capabilitycan also improve the spectral efficiency of a cellular network that carries local traffic. In this paper, we ask whether cellular networks should support D2D communications, physical-layer NWC, or both. To this end, we study the performance of mode selection algorithms that can be used in cellular networks that use physical-layer NWC and support D2D communications. We find that the joint application of D2D communication and NWC scheme yields additional gains compared with a network that implements only one of these schemes, provided that the network implements proper mode selection and resource allocation algorithms. We propose 2 mode selection schemes that aim to achieve high signal-to-interference-plus-noise ratio and spectral efficiency, respectively, and take into account the NWC and D2D capabilities of the network.

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