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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 networks2004Ingår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 17, nr 6, s. 507-512Artikel i tidskrift (Refereegranskat)
  • 2.
    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 coding2018Ingår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 31, nr 11, artikel-id e3594Artikel i tidskrift (Refereegranskat)
    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.

  • 3. G, Fodor
    Performance analysis of resource sharing policies in CDMA networks2007Ingår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 20, nr 2, s. 207-233Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider an interference-limited code division multiple access (CDMA) network, in which some of the service classes are explicit rate controlled. Such rate-controlled service classes include adaptive ones whose holding time does not depend on the sending rate, while the holding time of elastic services becomes longer when their sending rate is slowed down. We develop a Markov model that allows us to study the impact of employing service differentiation (prioritization) during admission control and rate control on the classwise blocking probabilities and throughputs. The admission control takes into account the interference from adjacent cells as a log-normally distributed random variable and employs service class and state-dependent (soft) blocking in addition to hard blocking. The state-dependent rate control algorithm takes into account the minimum and maximum requested rates of admitted sessions in a fairness policy-dependent manner. Our conclusion is that work conserving bandwidth sharing policies may have a major impact on the moments of the time spent in the system by elastic services, but only a minor one on the classwise blocking probabilities. When the admission control algorithm takes into account the neighbour cell caused interference, the blocking probability of all classes increases somewhat, but the throughput of the accepted sessions increases. Blocking prioritization in the soft blocking model affects the classwise total blocking probabilities but has little impact on the throughput of adaptive and elastic traffic.

  • 4. G, Fodor
    et al.
    M, Lindström
    On multi-cell admission control in CDMA networks2008Ingår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 21, nr 1, s. 25-50Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider a multi-cell (MC) code division multiple access (CDMA) system that supports multiple service classes, including peak rate allocated and elastic ones. Peak rate allocated sessions—when admitted into the system—transmit at a constant bit rate, while elastic sessions can be slowed down at the expense of increasing their residency time. Admitted sessions cause an instantaneous bit rate-dependent interference in neighbour cells. In this rather general setting, we propose a method to calculate the class-wise blocking probabilities as the functions of the estimated so-called inter-cell coupling factors. In the paper this coupling factor is the ratio between the uplink path gains to different Node-B:s (that can be easily obtained in a CDMA system from pilot measurement reports), but our model could include other coupling measures as well. We find that when these coupling factors are underestimated, the system may get into false states (FSs) or false rate states(FRSs) that lead to violating the noise rise threshold. As traffic becomes increasingly elastic, the probability of FSs decreases, but the probability of FRSs increases. Based on numerical results, we make the point that as the traffic becomes more elastic, avoiding the underestimation of these coupling factors as well as exercising MC admission control plays an increasingly important role in guaranteeing proper service quality.

  • 5. G, Fodor
    et al.
    P, Barta
    A, Marquetant
    A, Racz
    T, Henk
    Modelling and Analysis of Routing and Resource Allocation Techniques in Multi-service Networks1999Ingår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 12, nr 2, s. 103-123Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper a novel call level model based on the extension of the classical Erlang multi-rate model for broadband integrated services networks is proposed. We use the model to study routing strategies in multi-service networks where service classes with/without QoS guarantees coexist. Examples for such networks include ATM and IF-based integrated networks. In ATM, the CBR and VER service classes provide QoS guarantees, while the ABR and UBR service classes are of the best effort type. In IF, traditional TCP/IP traffic is of the best effort type, while new protocols like the RSVP or the differentiated services with central resource handling attempt to support QoS parameters. The coexistence of guaranteed and best effort traffic gives rise to new challenging problems since for a given elastic (best effort) connection the bottleneck link determines the available bandwidth and thereby puts constraints on the bandwidth at the other links along the connection's path. Since the available bandwidth fluctuates in rime following the load on the links, routing and link allocation in this environment together with blocking probability calculations and fairness issues need to be studied. By means of our proposed model we are able to conduct a survey of various routing and link allocation techniques as well as to develop a modified shortest path routing algorithm which, according to the numerical examples, performs well in this environment. Copyright (C) 1999 John Wiley & Sons, Ltd.

  • 6. G, Fodor
    et al.
    P, Skillermark
    Performance analysis of a reuse partitioning technique for multi-channel cellular systems supporting elastic services2009Ingår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 22, nr 3, s. 307-342Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For multi-cell systems employing intra-cell orthogonal communication channels, inter-cell interference mitigation techniques are expected to be one of the key radio resource management functions. In this paper we propose and analyze a simple reuse partitioning technique (with random and coordinated resource block allocation in neighbor cells) that is able to reduce inter-cell interference. We propose a model that is able to take into account that sessions dynamically enter and leave the system. Rigid sessions require a class-specific fixed number of resource blocks, while elastic sessions can enter the system if a minimum number of resources are allocated to them. In this rather general setting (and using the example of a system employing frequency division for multiple access) we analyze the system performance in terms of the expected number of channel collisions, the session-blocking probabilities, the signal-to-interference-and-noise ratio (SINR) and packet error rate performance. We present numerical results on the various trade-offs between these measures (including the trade-off between the reuse factor and the SINR performance) that provide insight into the behavior of multi-channel cellular systems and help dimensionalize the parameters of a reuse partitioned system.

  • 7. G, Fodor
    et al.
    S, Racz
    M, Telek
    On providing blocking probability and throughput guarantees in a multi-service environment2002Ingår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 15, nr 4, s. 257-285Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As the Internet evolves from a packet network supporting a single best effort service class towards an integrated infrastructure supporting several service classes-some with QoS guarantees-there is a growing interest in the introduction of admission control and in devising bandwidth sharing strategies, which meet the diverse needs of QoS-assured and elastic services. In this paper we show that the extension of the classical multi-rate loss model is possible in a way that makes it useful in the performance analysis of a future admission control based Internet that supports traffic with peak rate guarantee as well as elastic traffic. After introducing the model, it is applied for the analysis of a single link, where it sheds light on the trade-off between blocking probability and throughput. For the investigation of this trade-off, we introduce the throughput-threshold constraint, which bounds the probability that the throughput of a traffic flow drops below a predefined threshold. Finally, we use the model to determine the optimal parameter set of the popular partial overlap link allocation policy: we propose a computationally efficient algorithm that provides blocking probability- and throughput guarantees. We conclude that the model and the numerical results provide important insights in traffic engineering in the Internet. Copyright (C) 2002 John Wiley Sons, Ltd.

  • 8.
    Xia, Feng
    et al.
    School of Software, Dalian University of Technology, China.
    Yang, Laurence T.
    Department of Computer Science, St. Francis Xavier University, Canada.
    Wang, Lizhe
    Indiana University, USA.
    Vinel, Alexey
    Department of Communications Engineering, Tampere University of Technology, Finland.
    Internet of Things2012Ingår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 25, nr 9, s. 1101-1102Artikel i tidskrift (Refereegranskat)
  • 9.
    Zhang, Zhi
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Lu, Zhonghai
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Chen, Qiang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Yan, Xiaolang
    Zheng, Li-Rong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektroniksystem. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Code division multiple access/pulse position modulation ultra-wideband radio frequency identification for Internet of Things: concept and analysis2012Ingår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 25, nr 9, s. 1103-1121Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Radio frequency identification (RFID) is a compelling technology for Internet of Things (IoT). Ultra-wideband (UWB) technology is one promising wireless technique for future RFID, especially for high-throughput sensing applications. On-off keying UWB RFID system provides high pulse rate but suffers severe collisions that limit the system throughput. This paper proposes to utilize low pulse rate code division multiple access/pulse position modulation UWB in the tag-to-reader link to provide multiple tag access capability and build a high-throughput RFID system for IoT. We analyze asynchronous matched filter receiver and decorrelating receiver for multi-tag detection and design an effective medium access control scheme to optimize the network throughput. We propose an effective dynamic frame size adjustment algorithm on the basis of theoretical analysis and determine the preferable length of Gold codes. With a similar data rate, the throughput of the proposed system using the decorrelating receiver is 8.6 times higher than that of the electronic product code class 1 generation 2 system. Only using 1/10 pulse rate and 1/15 data rate, the proposed system outperforms the on-off keying UWB RFID system 1.4 times in terms of throughput.

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