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  • 51. D, Mariz
    et al.
    I, Cananéa
    D, Sadok
    G, Fodor
    Simulative analysis of access selection algorithms for multi-access networks2006In: 2006 International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM'06) / [ed] IEEE, New York: IEEE conference proceedings, 2006, p. 219-227Chapter in book (Other academic)
    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

  • 52.
    da Silva, Joakim M. B.
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Skouroumounis, C.
    Krikidis, I.
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Research, Stockholm, Sweden.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Energy-efficient full-duplex networks2020In: Green Communications for Energy-Efficient Wireless Systems and Networks, Institution of Engineering and Technology , 2020, p. 331-362Chapter in book (Other academic)
  • 53.
    Daei, Sajad
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Razavikia, Saeed
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Kountouris, Marios
    Communication Systems Department, EURECOM, 06410 Sophia Antipolis, France.
    Skoglund, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Information Science and Engineering.
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Research, Sweden.
    Fischione, Carlo
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Network and Systems Engineering.
    Blind Asynchronous Goal-Oriented Detection for Massive Connectivity2023In: 2023 21st International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks, WiOpt 2023, Institute of Electrical and Electronics Engineers Inc. , 2023, p. 167-174Conference paper (Refereed)
    Abstract [en]

    Resource allocation and multiple access schemes are instrumental for the success of communication networks, which facilitate seamless wireless connectivity among a growing population of uncoordinated and non-synchronized users. In this paper, we present a novel random access scheme that addresses one of the most severe barriers of current strategies to achieve massive connectivity and ultra reliable and low latency communications for 6G. The proposed scheme utilizes wireless channels’ angular continuous group-sparsity feature to provide low latency, high reliability, and massive access features in the face of limited time-bandwidth resources, asynchronous transmissions, and preamble errors. Specifically, a reconstruction-free goal oriented optimization problem is proposed which preserves the angular information of active devices and is then complemented by a clustering algorithm to assign active users to specific groups. This allows to identify active stationary devices according to their line of sight angles. Additionally, for mobile devices, an alternating minimization algorithm is proposed to recover their preamble, data, and channel gains simultaneously, enabling the identification of active mobile users. Simulation results show that the proposed algorithm provides excellent performance and supports a massive number of devices. Moreover, the performance of the proposed scheme is independent of the total number of devices, distinguishing it from other random access schemes. The proposed method provides a unified solution to meet the requirements of machine-type communications and ultra reliable and low latency communications, making it an important contribution to the emerging 6G networks.

  • 54.
    de Araujo, Gilderlan T.
    et al.
    Fed Inst Ceara, BR-62700000 Caninde, Brazil..
    de Almeida, Andre L. F.
    Univ Fed Ceara, Dept Teleinformat, Wireless Telecommun Res Grp GTEL, BR-60455970 Fortaleza, Ceara, Brazil..
    Boyer, Remy
    Univ Lille 1, CRIStAL Lab, F-59655 Villeneuve Dascq, France..
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Res, S-16480 Stockholm, Sweden..
    Semi-Blind Joint Channel and Symbol Estimation for IRS-Assisted MIMO Systems2023In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 71, p. 1184-1199Article in journal (Refereed)
    Abstract [en]

    Intelligent reflecting surface (IRS) is a promising technology for the 6$\text{th}$ generation of wireless systems, realizing the smart radio environment concept. This paper presents a novel tensor-based receiver for Intelligent reflecting surface (IRS)-assisted multiple-input multiple-output communications capable of jointly estimating the channels and the transmitted data streams in a semi-blind fashion. Assuming a fully passive IRS architecture and introducing a simple space-time coding scheme at the transmitter, the received signal model can be advantageously built using the PARATUCK tensor model, which can be seen as a hybrid of parallel factor analysis and Tucker models. A semi-blind receiver is derived by exploiting the algebraic structure of the PARATUCK tensor model. We first formulate a semi-blind receiver based on a trilinear alternating least squares method that iteratively estimates the two involved - IRS-base station and user terminal-IRS - communication channels and the transmitted symbol matrix. We discuss identifiability conditions that ensure the joint semi-blind recovery of the involved channel and symbol matrices and propose a joint design of the coding and IRS reflection matrices to optimize the receiver performance. We also formulate an enhanced two-stage semi-blind receiver that efficiently exploits the direct link to refine the channel and symbol estimates iteratively. In particular, we discuss the impact of an imperfect IRS absorption (residual reflection) on the performance of the proposed receiver. Numerical results are proposed for performance evaluation in several system settings in terms of the normalized mean squared error of the estimated channels and the achieved symbol error rate, corroborating the merits of the proposed semi-blind receiver in comparison to competing methods.

  • 55.
    de Araujo, Gilderlan T.
    et al.
    Univ Fed Ceara, Dept Teleinformat, Wireless Telecommun Res Grp GTEL, BR-60020181 Fortaleza, Ceara, Brazil..
    Gomes, Paulo R. B.
    Univ Fed Ceara, Dept Teleinformat, Wireless Telecommun Res Grp GTEL, BR-60020181 Fortaleza, Ceara, Brazil..
    de Almeida, Andre L. F.
    Univ Fed Ceara, Dept Teleinformat, Wireless Telecommun Res Grp GTEL, BR-60020181 Fortaleza, Ceara, Brazil..
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Res, S-16480 Stockholm, Sweden..
    Makki, Behrooz
    Ericsson, Ericsson Res, S-41756 Gothenburg, Sweden..
    Semi-Blind Joint Channel and Symbol Estimation in IRS-Assisted Multiuser MIMO Networks2022In: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 11, no 7, p. 1553-1557Article in journal (Refereed)
    Abstract [en]

    Intelligent reflecting surface (IRS) is a promising technology for beyond of the wireless communications. In fully passive IRS-assisted systems, channel estimation is challenging and should be carried out only at the base station or at the terminals since the elements of the IRS are incapable of processing signals. In this letter, we formulate a tensor-based semi-blind receiver that solves the joint channel and symbol estimation problem in an IRS-assisted multi-user multiple-input multiple-output system. The proposed approach relies on a generalized PARATUCK tensor model of the signals reflected by the IRS, based on a two-stage closed-form semi-blind receiver using Khatri-Rao and Kronecker factorizations. Simulation results demonstrate the superior performance of the proposed semi-blind receiver, in terms of the normalized mean squared error and symbol error rate, as well as a lower computational complexity, compared to recently proposed parallel factor analysis-based receivers.

  • 56.
    Della Penda, Demia
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson AB, Stockholm, 164 83, Sweden.
    Wichman, Risto
    Aalto Univ, Sch Elect Engn, FI-00076 Aalto, Finland..
    Charalambous, Themistoklis
    Aalto Univ, Sch Elect Engn, FI-00076 Aalto, Finland..
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson AB, Stockholm, 164 83, Sweden.
    Johansson, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    A Distributed Mode Selection Scheme for Full-Duplex Device-to-Device Communication2019In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 68, no 10, p. 10267-10271Article in journal (Refereed)
    Abstract [en]

    Networks with device-to-device(D2D) technology allow for two possible communication modes: traditional communication via the base station, and direct communication between the users. Recent studies show that in-band full-duplex(IBFD) operations can be advantageously combined with D2D communication to improve the spectral efficiency. However, no algorithms for selecting the communication mode of mobile users in IBFD networks have yet appeared in the literature. In this paper, we design a distributed mode selection scheme for users in D2D-enabled IBFD networks. The proposed scheme maximizes the users prob-ability of successful communication by leveraging only existing signaling mechanisms.

  • 57. Dimou, Konstantinos
    et al.
    Fodor, Gabor
    KTH, School of Electrical Engineering (EES). Ericsson Research.
    Cavalcanti, Francisco Rodrigo P.
    MACIEL, Tarcísío
    Dynamic Resource Selection to Reduce Interference That Results From Direct Device-to-Device Communications2013Patent (Other (popular science, discussion, etc.))
    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.

  • 58. Dimou, Konstantinos
    et al.
    Simonsson, Arne
    Müller, Walter
    Fodor, Gabor
    Furuskär, Anders
    Intercell interference coordination for radio resource control2008Patent (Other (popular science, discussion, etc.))
    Abstract [en]

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

  • 59. Eriksson, Anders
    et al.
    Fodor, Gabor
    Flow control packet mobile communication2004Patent (Other (popular science, discussion, etc.))
    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.

  • 60. Ernst, Nordstrom
    et al.
    Soren, Blaabjerg
    Gabor, Fodor
    Admission control of CBR/VBR and ABR/UBR call arrival streams: A Markov decision approach1997In: Proceedings of IEEE ATM Workshop 1997 / [ed] IEEE, New York: IEEE , 1997, p. 113-122Chapter in book (Other academic)
  • 61. Fallgren, Mikael
    et al.
    Abbas, Taimoor
    Allio, Sylvain
    Alonso-Zarate, Jesus
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Gallo, Laurent
    Kousaridas, Apostolos
    Li, Yilin
    Li, Zexian
    Li, Zhongfeng
    Luo, Jian
    Mahmoodi, Toktam
    Svensson, Tommy
    Vivier, Guillaume
    Multicast and Broadcast Enablers for High-Performing Cellular V2X Systems2019In: IEEE transactions on broadcasting, ISSN 0018-9316, E-ISSN 1557-9611, Vol. 65, no 2, p. 454-463Article in journal (Refereed)
    Abstract [en]

    This paper focuses on capabilities enabled by 5G connectivity in the cooperative, connected and autonomous cars, and elaborates on two technical enablers. One of the technical enablers consists of a beamformed broadcast/multicast technology that builds on adaptive and robust beam management techniques at the air interface. The other proposed technical component aims to improve the end-to-end architectural design of 5G networks to enable efficient broadcast and multicast transmissions for vehicle-to-anything services. Finally, the key results of multicast and broadcast technical components are described and ongoing and future areas of work and research are detailed.

  • 62.
    Fallgren, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Oddsdóttir, H. Æ
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Fodor, G.
    An optimization approach to joint cell and power allocation in multicell networks2011In: IEEE Int Conf Commun, 2011, p. 5963591-Conference paper (Refereed)
    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.

  • 63. Fodor, G
    et al.
    Barta, P
    Marquetant, A
    Rácz, A
    Henk, T
    QoS Routing Strategies in Broadband Multiservice Networks1998In: / [ed] IEEE, null, 1998, p. 184-193Conference paper (Refereed)
  • 64. Fodor, G
    et al.
    Dahlman, E
    Parkvall, S
    Mildh, G
    Reider, N
    Miklos, G
    Turanyi, Z
    Design Aspects of Network Assisted Device-to-Device Communications2012In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 50, no 3, p. 170-177Article in journal (Refereed)
    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.

  • 65. Fodor, G
    et al.
    Gaál, B
    Haraszti, Zs
    Henk, T
    Ziaja, Zs
    Dahlquist, I
    A Flexible Simulation Platform for ATM Networks1994In: / [ed] Kayran, Ali L; Lehmann, Axel; Ören, Tuncer I, 1994, p. 79-81Conference paper (Refereed)
  • 66. Fodor, G
    et al.
    Marosits, T
    Molnár, S
    A General Traffic Control Framework in ATM Networks1996Conference paper (Refereed)
  • 67. Fodor, G
    et al.
    Olin, B
    Persson, F
    Roobol, C
    Williams, B
    Differentiated and Integrated Services for IP Applications over UMTS2003In: Wireless IP and Building the Mobile Internet / [ed] Dixit, Sudhir; Prasad, Ramjee, London: London , 2003, p. 133-160Chapter in book (Other academic)
  • 68.
    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 Sciences2018Doctoral thesis, monograph (Other academic)
    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.

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  • 69. Fodor, Gabor
    Method and apparatus for allocating radio resources in a mobile radio network2011Patent (Other (popular science, discussion, etc.))
    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.

  • 70.
    Fodor, Gabor
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research.
    Method and Arrangement for Adjusting Signal-to-Interference-Plus-Noise-Ratio In a Device-to-Device Communication2013Patent (Other (popular science, discussion, etc.))
    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.

  • 71. Fodor, Gabor
    Method and arrangement in a communication system2014Patent (Other (popular science, discussion, etc.))
    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.

  • 72.
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Res, Stockholm, Swede.
    Mode selection schemes for unicasting device-to-device communications supported by network coding2018In: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 31, no 11, article id e3594Article in journal (Refereed)
    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.

  • 73.
    Fodor, Gabor
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Performance Comparison of Practical Resource Allocation Schemes for Device-to-Device Communications2018In: Wireless Communications & Mobile Computing, ISSN 1530-8669, E-ISSN 1530-8677, article id 3623075Article in journal (Refereed)
    Abstract [en]

    Device-to-device (D2D) communications in cellular spectrum have the potential of increasing the spectral and energy efficiency by taking advantage of the proximity and reuse gains. Although several resource allocation (RA) and power control (PC) schemes have been proposed in the literature, a comparison of the performance of such algorithms as a function of the available channel state information has not been reported. In this paper, we examine which large scale channel gain knowledge is needed by practically viable RA and PC schemes for network assisted D2D communications. To this end, we propose a novel near-optimal and low-complexity RA scheme that can be advantageously used in tandem with the optimal binary power control scheme and compare its performance with three heuristics-based RA schemes that are combined either with the well-known 3GPP Long-Term Evolution open-loop path loss compensating PC or with an iterative utility optimal PC scheme. When channel gain knowledge about the useful as well as interfering (cross) channels is available at the cellular base station, the near-optimal RA scheme, termedMatching, combined with the binary PC scheme is superior. Ultimately, we find that the proposed low-complexity RA + PC tandem that uses some cross-channel gain knowledge provides superior performance.

  • 74.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research.
    Belleschi, Marco
    Kazmi, Muhammad
    Pre-Emption and Resource Allocation Prioritization for D2D Communications2016Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A network node assigns resources for use in wireless communication based on priority. The network node receives, from a wireless communication device, a service request message that requests connection of a communication session. The network node determines a priority level for the requested communication session. The priority level comprises a cellular layer admission priority of whether the network node can preempt cellular resources of an existing communication session in order to admit the requested communication session on the cellular layer, and a device-to-device (D2D) layer admission priority of whether the network node can preempt D2D resources of an existing communication session in order to admit the requested communication session on the D2D layer. The network node assigns resources based at least in part on the priority level. The resources are used for D2D communication or cellular communication.

  • 75.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research.
    Belleschi, Marco
    Lindoff, Bengt
    Wilhelmsson, Leif
    Device Discovery of Second User Equipments In a Second Network for D2D Communication2012Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    According to a first aspect of embodiments herein, a method in a first network node for handling device discovery of second user equipments in a second network for Device-to-Device (D2D) communication is provided. The network node is comprised in a first network. The first network node obtains information from a second network node within the second network. The information relates to resources for sending device discovery beacon signals in a second network. The first network node sends the obtained information to a first user equipment served by the first network node. The obtained information relates to said resources for sending device discovery beacon signals in the second network. The information enables the first user equipment to discover beacon signals from the second user equipments in the second network and/or to send beacon signals to be discovered by the second user equipments in the second network.

  • 76.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Res, Stockholm, Sweden..
    Chae, Chan-Byoung
    Yonsei Univ, Sch Integrated Technol, Seoul, South Korea..
    Wichman, Risto
    Nokia Res Ctr, Palo Alto, CA USA.;Aalto Univ, Sch Elect Engn, Aalto, Finland..
    Sabharwal, Ashutosh
    WARP Project, Aalto, Finland.;Rice RENEW, Aalto, Finland..
    Suraweera, Himal A.
    Univ Peradeniya, Dept Elect & Elect Engn, Kandy, Sri Lanka..
    Rao, Raghu
    Univ Calif Los Angeles, Digital Commun, Los Angeles, CA 90024 USA..
    Alves, Hirley
    Univ Oulu, Machinetype Wireless Commun Grp, Ctr Wireless Commun, Oulu, Finland..
    Full duplex communications theory, standardization, and practice2021In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 28, no 1, p. 10-11Article in journal (Refereed)
  • 77.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Dahlman, Erik
    KLANG, Göran N.
    Parkvall, Stefan
    Wilhelmsson, Leif
    Network nodes, devices and methods therein for enabling device to device communication2012Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The embodiments herein relate to network nodes, devices and methods therein. In particular, embodiments herein relate to enabling device to device communication in a radio communications network.

  • 78.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research, Sweden.
    Di Marco, Piergiuseppe
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Telek, M.
    On the impact of antenna correlation on the pilot-data balance in multiple antenna systems2015In: 2015 IEEE International Conference On Communications (ICC), IEEE conference proceedings, 2015, Vol. 2015, p. 2590-2596Conference paper (Refereed)
    Abstract [en]

    We consider the uplink of a single cell single input multiple output (SIMO) system, in which the mobile stations use intra-cell orthogonal pilots to facilitate uplink channel estimation. In such systems, the problem of transmission power balancing between pilot and data is known to have a large impact on the mean square error (MSE) for the received signal and, consequently, on the achievable uplink data rate. In this paper, we derive a closed form expression of the MSE for the received signal as a function of the pilot and data power levels under a per-user sum pilot-data power constraint. As a major contribution, our model is developed for arbitrary channel covariance matrices and it enables us to study the impact of the number of antennas and antenna correlation structures, including the popular 3GPP spatial channel model. Numerical results suggest that the effect of the antenna spacing is limited, but the angle of arrival and angular spread have a strong and articulated impact on the MSE performance. Moreover, as the number of antennas at the base station grows large, we show that a higher percentage of the power budget should be allocated to pilot signals than with a lower number of antennas.

  • 79.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research, Sweden.
    Di Marco, Piergiuseppe
    Telek, Miklos
    On the Impact of Antenna Correlation and CSI Errors on the Pilot-to-Data Power Ratio2016In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 64, no 6, p. 2622-2633Article in journal (Refereed)
    Abstract [en]

    In systems employing pilot-symbol aided channel estimation, the pilot-to-data power ratio is known to have a large impact on performance. Therefore, previous works proposed methods setting the pilot power such that either the weighted sum of the mean squared error (MSE) of the estimated data symbols is minimized or the overall spectral efficiency (SE) is maximized. However, previous works did not take into account the impact of correlated antennas and channel state information (CSI) errors on the optimal pilot power setting. In this paper, we consider the uplink of a multiuser multiple-input multiple-output (MU MIMO) system employing a receiver that minimizes the MSE of the received data symbols in the presence of CSI errors and derive closed-form expressions for theMSE and the achievable SE. These expressions take into account the impact of antenna correlation and CSI errors, and are a function of pilot power and the number of receive antennas. The analytical and numerical results can help set the pilot power, minimizing the MSE in multiple antenna systems.

  • 80.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. Ericsson Research, Stockholm, Sweden.
    Di Marco, Piergiuseppe
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Telek, Miklos
    Performance analysis of block and comb type channel estimation for massive MIMO systems2014In: Proceedings of the 2014 1st International Conference on 5G for Ubiquitous Connectivity, 5GU 2014, 2014, p. 62-69Conference paper (Refereed)
    Abstract [en]

    For pilot sequence based multiple input multiple output (MIMO) channel estimation, the arrangements of pilot symbols, such as the block or comb type arrangement, is known to play an important role. In this paper we compare the performance of block and comb pilot symbol patterns in terms of uplink mean square error (MSE) and spectral efficiency when the receiver at the base station employs least square (LS) or minimum mean square error (MMSE) channel estimation and MMSE equalizer for uplink data reception. For this system, we derive a closed form solution for the MSE and spectral efficiency that allows us to obtain exact results for an arbitrary number of antennas. Our key observation is that the comb pilot arrangement allows for unequal pilot-data power allocation in the frequency domain, which leads to a significant spectral efficiency increase. This spectral efficiency increase is particularly important with LS estimation and as the number of base station antennas grows large. It also gives noticeable gains with MMSE estimation. Our main conclusion is that with a large number of antennas, unequal power allocation facilitated by comb arrangement can give large gains over alternative pilot arrangements.

  • 81. Fodor, Gabor
    et al.
    Di Marco, Piergiuseppe
    Telek, Miklós
    On Minimizing the MSE in the Presence of Channel State Information Errors2015In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 19, no 9, p. 1604-1607Article in journal (Refereed)
    Abstract [en]

    We consider the uplink of a multiuser multiple input multiple output (MU MIMO) system, in which the base station acquires channel state information (CSI) for which the estimation error depends on the resources assigned to the uplink pilot symbols. For this system, we first derive the receiver that minimizes the mean square error (MSE) of the uplink detected data symbols, as opposed to the naïve receiver that does not minimize the MSE in the presence of CSI errors. We then derive a closed form expression for the MSE as a function of the employed pilot-to-data power ratio, number of antennas and the MU MIMO interference power. This expression allows us to gain the insight that the gain of using the actual MMSE receiver as opposed to the naïve receiver becomes particularly important when the number of BS antennas is large.

  • 82.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Do, Hieu
    Ericsson Research.
    Ashraf, Shehzad
    Ericsson Research.
    Blasco-Serrano, Ricardo
    KTH.
    Sun, Wanlu
    Ericsson Research.
    Belleschi, M.
    Ericsson Research.
    Hu, Liang
    Ericsson Research.
    Supporting Enhanced Vehicle-to-Everything Services by LTE Release 15 Systems2019In: IEEE Communications Standards Magazine, ISSN 2471-2825, Vol. 3, no 1, p. 26-33, article id 8771315Article in journal (Refereed)
    Abstract [en]

    Recognizing the increasing demand for intelligent transportation systems, the initial set of the Long Term Evolution (LTE) technical enablers for vehicle-to-everything (V2X) communication services has been substantially enhanced in Release 15 (Rel-15) and will be further developed in Rel-16. These enhancements are driven by the 25 use cases identified for V2X by the Third Generation Partnership Project, which are categorized as vehicle platooning, extended sensors, advanced driving, and remote driving. In this article, we provide an overview of the new V2X features supported by Rel-15 LTE systems, including carrier aggregation, higher-order modulation, low latency support, and new resource management solutions. We also discuss the possible next steps of the 3GPP V2X technology evolution in the upcoming releases.

  • 83. Fodor, Gabor
    et al.
    Eriksson, Anders
    Method and system for handling context of data packet flows2003Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to the handling of context of data packet flows. As mentioned, there is a need of a coordination mechanism for the transfer of context for flows that belong to the same session. One object with the invention is to offer a coordination mechanism for the handling of context associated to flows that belong to the same session. The above-mentioned object is achieved by a context procedure, in which the total context for a session is divided into one common context and one dynamic context per IP flow. The common context is handled by a centralized control node, such as a Midcom Agent, and the dynamic context is handled by a middlebox associated to an access router. The context transfer procedures for the two types of contexts are coordinated so that an unambiguous session control is maintained.

  • 84.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Res, S-16480 Stockholm, Sweden..
    Fodor, Sebastian
    Stockholm Univ, S-10691 Stockholm, Sweden..
    Telek, Miklos
    Budapest Univ Technol & Econ, H-1117 Budapest, Hungary.;MTA BME Informat Syst Res Grp, H-1117 Budapest, Hungary..
    MU-MIMO Receiver Design and Performance Analysis in Time-Varying Rayleigh Fading2022In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 70, no 2, p. 1214-1228Article in journal (Refereed)
    Abstract [en]

    Minimizing the symbol error in the uplink of multi-user multiple input multiple output systems is important, because the symbol error affects the achieved signal-to-interference-plus-noise ratio (SINR) and thereby the spectral efficiency of the system. Despite the vast literature available on minimum mean squared error (MMSE) receivers, previously proposed receivers for block fading channels do not minimize the symbol error in time-varying Rayleigh fading channels. Specifically, we show that the true MMSE receiver structure does not only depend on the statistics of the CSI error, but also on the autocorrelation coefficient of the time-variant channel. It turns out that calculating the average SINR when using the proposed receiver is highly non-trivial. In this paper, we employ a random matrix theoretical approach, which allows us to derive a quasi-closed form for the average SINR, which allows to obtain analytical exact results that give valuable insights into how the SINR depends on the number of antennas, employed pilot and data power and the covariance of the time-varying channel. We benchmark the performance of the proposed receiver against recently proposed receivers and find that the proposed MMSE receiver achieves higher SINR than the previously proposed ones, and this benefit increases with increasing autoregressive coefficient.

  • 85.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson Res, S-16480 Stockholm, Sweden.
    Fodor, Sebastian
    Stockholm Univ, S-10691 Stockholm, Sweden..
    Telek, Miklos
    Budapest Univ Technol & Econ, H-1111 Budapest, Hungary.;MTA BME Informat Syst Res Grp, H-1051 Budapest, Hungary..
    Performance Analysis of a Linear MMSE Receiver in Time-Variant Rayleigh Fading Channels2021In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 69, no 6, p. 4098-4112Article in journal (Refereed)
    Abstract [en]

    The performance of the uplink of single and multiuser multiple input multiple output (MIMO) systems depends crucially on the receiver architecture and the quality of channel state information at the receiver. Therefore, several previous works have developed minimum mean squared error (MMSE) receivers and proposed balancing the resources spent on acquiring channel state information and transmitting the payload of data packets. Somewhat surprisingly, the most popular MIMO linear MMSE receivers do not exploit the correlation structure that is present in autoregressive Rayleigh fading environments. Therefore, in this article we first develop a new linear receiver that not only takes channel state information errors into account in minimizing the MSE of the received data symbols, but it also utilizes that the subsequent noisy channel coefficients are correlated. For this new linear MMSE receiver, we derive the achieved MSE as a function of the number of receive antennas and the pilot-to-data power ratio. Interestingly, we find that the pilot power that minimizes the MSE of the data symbols does not depend on the number of antennas and that the new linear MMSE receiver outperforms previously proposed MIMO receivers when the autocorrelation coefficient of the channel is high.

  • 86.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Johansson, Mikael
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Demia, Penda
    Marco, Belleschi
    Abrardo, Andrea
    A Joint Power Control and Resource Allocation Algorithm for D2D Communications2012Report (Other academic)
    Abstract [en]

    We consider the problem of joint power control, signal-to-noise-and-interference-ratio (SINR)target setting, mode selection and resource allocation for cellular network assisteddevice-to-device (D2D) communications.This problem is important for fourth generation systems, such as the release under study of the Long TermEvolution Advanced (LTE-A) system standardized by the Third Generation Partnership Project (3GPP).While previous works on radio resource management (RRM) algorithms for D2D communications dealt withmode selection and power control, the problem of resource allocation for the integrated cellular-D2Denvironment and in particularthe joint problem of mode selection, resource allocation and power allocation has not been addressed.We propose a utility function maximization approach that allows to take into account the inherenttrade off between maximizing spectrum efficiency and minimizing the required sum transmit power.We implement the proposed RRM algorithms in a realistic system simulator and report numericalresults that indicate large gains of D2D communications both in terms of spectrum- and energyefficiency.

    Download full text (pdf)
    fulltext
  • 87.
    Fodor, Gabor
    et al.
    Ericsson Research, Sweden.
    Johansson, Mikael
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Soldati, Pablo
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Near optimum power control and precoding under fairness constraints in network MIMO systems2009In: International Journal of Digital Multimedia Broadcasting, ISSN 1687-7578, Vol. 2010, p. 251719-Article in journal (Refereed)
    Abstract [en]

    We consider the problem of setting the uplink signal-to-noise-and- interference (SINR) target and allocating transmit powers for mobile stations in multicell spatial multiplexing wireless systems. Our aim is twofold: to evaluate the potential of such mechanisms in network multiple input multiple output (MIMO) systems, and to develop scalable numerical schemes that allow real-time near-optimal resource allocation across multiple sites. We formulate two versions of the SINR target and power allocation problem: one for maximizing the sum rate subject to power constraints, and one for minimizing the total power needed to meet a sum-rate target. To evaluate the potential of our approach, we perform a semianalytical study in Mathematica using the augmented Lagrangian penalty function method. We find that the gain of the joint optimum SINR setting and power allocation may be significant depending on the degree of fairness that we impose. We develop a numerical technique, based on successive convexification, for real-time optimization of SINR targets and transmit powers. We benchmark our procedure against the globally optimal solution and demonstrate consistently strong performance in realistic network MIMO scenarios. Finally, we study the impact of near optimal precoding in a multicell MIMO environment and find that precoding helps to reduce the sum transmit power while meeting a capacity target.

  • 88. Fodor, Gabor
    et al.
    Johnson; c/o Robertsson, OYAMA
    Widegren, Ina
    Williams, Brian
    RSVP handling in 3G networks2001Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    In a radio network, the implementation of IP signaling may be used to provide end-to-end Quality of Service. This may be accomplished by mapping corresponding parameters between the IP protocol and the radio network protocol in order to achieve the desired delay and bandwidth requirements. Various events in the state machines of the protocols may also be used to trigger interworking functions.

  • 89.
    Fodor, Gabor
    et al.
    Ericsson Research.
    Kazmi, Muhammad
    Control of the Radio Emission of a Mobile Terminal in a Criticial Area2008Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Methods and arrangements (400, 600) in network nodes (101, 102, 110) for controlling radio emission from a mobile terminal (102) are provided. The mobile terminal (102) is located in a critical area. The network node sends a location parameter of the critical area, wherein the location parameter indicates a geographical location of the critical area. The first radio network node (101, 110) sends a first set of control parameters to the mobile terminal. The mobile terminal determines a geographical location of the mobile terminal and controls radio emission from the mobile terminal based on the first set of control parameters, the location parameter and the geographical location of the mobile terminal. Methods and arrangements (900) in a first radio network node (101, 110) for performing admission control are provided. The first radio network node (101, 110) receives a service request. In another step, the first radio network node (101, 110) denies the service request if an aggregated number of mobile terminals attached to the first radio network node (101, 110) exceeds a predetermined mobile terminal number or total received power at the first radio network node exceeds a predetermined threshold.

  • 90.
    Fodor, Gabor
    et al.
    Ericsson Research.
    Kazmi, Muhammad
    Reducing Battery Power Consumption of a User Equipment2007Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a method and arrangements for saving battery power consumption of a UE in mobile telecommunication system. The method comprises the step of checking whether the UE fulfills at least one of the pre-determined criteria that a subscriber explicitly requests to receive paging at extended DRX cycle and that a new cell is not reselected during a pre-determined time. If the at least one of the pre-determined criteria is fulfilled the step of applying an extended DRX cycle is performed.

  • 91.
    Fodor, Gabor
    et al.
    Ericsson Research.
    Kazmi, Muhammad
    User Equipment and  Radio Network Node, and Methods Therein for Device-to-Device Communication2011Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Embodiments relate to device-to-device (D2D) communications in a communications network (1), wherein the communications network (1) comprises a first user equipment (10), a first radio network node (14) serving the first user equipment (10), a second user equipment (12). and a D2D capable radio network node (18,18). The first user equipment (TO) is configured to recognize a second user equipment (12) to have a D2D communication with and to perform a cell change from the first radio network node (14) to the D2D capable radio network node (16,18), when the first radio network node (14) does not have D2D capability.

  • 92. Fodor, Gabor
    et al.
    Kazmi, Muhammad Ali
    Discontinuous transmission and reception2007Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    There is provided a method of determining a discontinuous reception and/or transmission cycle length, the method comprising determining information relevant to the cycle length from a high layer in a protocol stack; providing the information to a lower layer in the protocol stack; and in the lower layer of the protocol stack, determining the cycle length from the information.

  • 93. Fodor, Gabor
    et al.
    Kazmi, Muhammad
    Siomina, Iana
    Coverage extension of position services2010Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present solution relates to a method in a user equipment (110) for providing navigation signals to a navigator device (104) for use in determining the location of the navigator device. The user equipment (110) selects a plurality of satellites whose signals are to be emulated. After determining the position of the user equipment (110), the user equipment (110) translates the determined position to emulating navigation signals using a parameter derived from each of the respective selected satellites. The user equipment (110) transmits, to the navigator device (104), the emulated navigation signals. The emulated navigation signals enable the navigator device to determine the location of the navigator device (104).

  • 94.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Lu, Qianxi
    Miao, Qingyu
    Brahmi, Nadia
    Clustering Schemes for D2D Communications Under Partial/No Network Coverage2013Conference paper (Other academic)
    Abstract [en]

    Device-to-Device (D2D) communication has been proposed to support local services by enabling devices to directly connect to each other when being in proximity. To start direct communications, a device must first discover that other devices are in the proximity and that they are relevant in a certain context (i.e. can offer a specific service). This task becomes particularly challenging in out-of-network coverage.  In this paper, we propose three clustering schemes that assist a device discovery and associating with other devices found relevant in a given context. We compare the efficiency of the proposed approaches in terms of discovery ratio, clustering time and energy consumption and study the tradeoff between these performance metrics that need to be considered when selecting one of the grouping schemes. In particular, the simulation results prove that grouping devices based on their capabilities taking into account the exchanged radio signal strengths ensure, in most of the scenarios, the balance between high discovery ratio, short latency and energy efficiency. This work has been partially performed in the framework of the FP7 project ITC 317669 METIS.

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    fulltext
  • 95. Fodor, Gabor
    et al.
    M, Pióro
    A, Szentesi
    G, Malicsko
    T, Cinkler
    Dimensioning and optimizationof multi-rate networks supporting elastic traffic2000Other (Other academic)
  • 96.
    Fodor, Gabor
    et al.
    Ericsson Research.
    Mildh, Gunnar
    VIKBERG, Jari
    Hedberg, Tomas
    Closed Subscriber Group (CSG) Handling for Supporting Network Sharing of Home Base Stations2011Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A system and method for enhanced support for handling of Closed Subscriber Groups (CSGs) and sharing of Radio Access Network (RAN) for home base stations and other small cells. An enhanced System Information (SI) structure indicates multiple CSG IDs and CSG Indications, thereby making it possible to support different CSG IDs and CSG Indications for every Public Land Mobile Network Identity (PLMN-ID) and also to support a PLMN-ID with multiple associated CSG IDs and CSG Indications. The enhanced SI makes it possible to have different CSG IDs for different operators, to have multiple CSG IDs for one operator (i.e., a single PLMN), and to selectively use the CSG concept for some PLMNs (as given by their respective CSG Indications), but not for all.; A network of base stations (e.g., a RAN) thus can be effectively shared by multiple operators, leading to better cellular coverage, peak rates, and capacity.

  • 97.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Pap, L.
    Telek, M.
    Recent advances in acquiring channel state information in cellular MIMO systems2019In: Infocommunications Journal, ISSN 2061-2079, Vol. 11, no 3, p. 2-12Article in journal (Refereed)
    Abstract [en]

    In cellular multi-user multiple input multiple output (MU-MIMO) systems the quality of the available channel state information (CSI) has a large impact on the system performance. Specifically, reliable CSI at the transmitter is required to determine the appropriate modulation and coding scheme, transmit power and the precoder vector, while CSI at the receiver is needed to decode the received data symbols. Therefore, cellular MUMIMO systems employ predefined pilot sequences and configure associated time, frequency, code and power resources to facilitate the acquisition of high quality CSI for data transmission and reception. Although the trade-off between the resources used for pilot and user data transmission has been known for long, the near-optimal configuration of the available system resources for pilot and data transmission is a topic of current research efforts. Indeed, since the fifth generation of cellular systems utilizes heterogeneous networks in which base stations are equipped with a large number of transmit and receive antennas, the appropriate configuration of pilot-data resources becomes a critical design aspect. In this article, we review recent advances in system design approaches that are designed for the acquisition of CSI and discuss some of the recent results that help to dimension the pilot and data resources specifically in cellular MU-MIMO systems.

  • 98.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control). Ericsson AB, Linköping, Sweden.
    Penda, D. D.
    Ericsson AB, Linköping, Sweden.
    Belleschi, M.
    Ericsson AB, Linköping, Sweden.
    Johansson, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Decision and Control Systems (Automatic Control).
    Abrardo, A.
    Univ Siena, Dept Informat Engn, Siena, Italy..
    A comparative study of power control approaches for device-to-device communications2013In: IEEE International Conference on Communications, Institute of Electrical and Electronics Engineers Inc. , 2013, p. 6008-6013Conference paper (Refereed)
    Abstract [en]

    Device-to-device (D2D) communications integrated into cellular networks is a means to take advantage of the proximity of devices and thereby to increase the user bitrates and system capacity. D2D communications has recently been proposed for the 3GPP Long Term Evolution (LTE) system as a method to increase the spectrum- and energy-efficiency. Such systems support a wide range of power control schemes based on a combination of open-loop and closed-loop components and there is a need to set the associated control parameters such that spectrum- and energy-efficiency targets are met. In this paper we study the performance of various power control strategies applicable to D2D communications in LTE networks and compare them with a utility function maximization approach that balances spectrum efficiency and the total transmission power. Our reference scheme is based on a fully distributed algorithm that iteratively sets the signal-to-interference-plus-noise (SINR) targets and corresponding transmit power levels. We find that the LTE-based power control approach performs close to the optimal scheme provided that the associated parameters are properly set

  • 99. Fodor, Gabor
    et al.
    Racz, Sándor
    Telek, Miklos
    Optimizing throughput blocking through joint use of connection capacity2000Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates generally to the field of communication networks and more particularly to a common value of a junction capacitance and an assignment of a link bandwidth in such networks.

  • 100.
    Fodor, Gabor
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Rajatheva, N.
    Zirwas, W.
    Thiele, L.
    Kurras, M.
    Guo, K.
    Tolli, A.
    Sorensen, J. H.
    Carvalho, E. D.
    An Overview of Massive MIMO Technology Components in METIS2017In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 55, no 6, p. 155-161, article id 7946939Article in journal (Refereed)
    Abstract [en]

    As the standardization of full-dimension MIMO systems in the Third Generation Partnership Project progresses, the research community has started to explore the potential of very large arrays as an enabler technology for meeting the requirements of fifth generation systems. Indeed, in its final deliverable, the European 5G project METIS identifies massive MIMO as a key 5G enabler and proposes specific technology components that will allow the cost-efficient deployment of cellular systems taking advantage of hundreds of antennas at cellular base stations. These technology components include handling the inherent pilot-data resource allocation trade-off in a near optimal fashion, a novel random access scheme supporting a large number of users, coded channel state information for sparse channels in frequency-division duplexing systems, managing user grouping and multi-user beamforming, and a decentralized coordinated transceiver design. The aggregate effect of these components enables massive MIMO to contribute to the METIS objectives of delivering very high data rates and managing dense populations.

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