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    Wyświetlanie 1-12 z 12
    Tytuł:
    Performance and Limitations of VDSL2-based Next Generation Access Networks
    Autorzy:
    Heliotis, G.
    Dimos, L.-P.
    Kordoulis, I.
    Agapiou, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/307882.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    DSL networks
    impulse noise
    VDSL2 next generation access networks
    crosstalk
    Opis:
    In this paper, we first briefly review the main operational aspects of FTTC (xPON)/VDSL2 access networks. Then, we present performance measurements with respect to network sub loop operating length and VDSL2 operational profiles (8b, 12a, 17a), studying the rates that can be achieved at different scenarios. We then provide results of the effect of stationary crosstalk and non-stationary impulse noise on the provisioned service in an operating VDSL2 access network.
    Źródło:
    Journal of Telecommunications and Information Technology; 2013, 1; 98-102
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    RoFnet - Reconfigurable Radio over Fiber Network Architecture Overview
    Autorzy:
    Medeiros, M.
    Avó, R.
    Laurencio, P.
    Correia, N.
    Barradas, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/308954.pdf
    Data publikacji:
    2009
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    optical access networks
    optical single sideband
    radio over fiber
    reflective semiconductor optical amplifiers
    wavelength division multiplexing
    Opis:
    This paper introduces the basic operational concepts of the RoFnet - reconfigurable radio over fiber network, which is a project supported by the Portuguese Foundation forScience and Technology. This project proposes an innovative radio over fiber optical access network architecture, which combines a low cost base station (BS) design, incorporating reflective semiconductor optical amplifiers, with fiber dispersion mitigation provided by optical single sideband modulation techniques. Optical wavelength division multiplexing (WDM) techniques are used to simplify the access network architecture allowing for different BSs to be fed by a common fiber. Different wavelength channels can be allocated to different BSs depending on user requirements. Additionally, in order to improve radio coverage within a cell, it is considered a sectorized antenna interface. The combination of subcarrier multiplexing with WDM, further simplifies the network architecture, by using a specific wavelength channel to feed an individual BS and different subcarriers to drive the individual antenna sectors within the BS.
    Źródło:
    Journal of Telecommunications and Information Technology; 2009, 1; 38-43
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of Latency-Aware Network Slicing in 5G Packet xHaul Networks
    Autorzy:
    Klinkowski, Mirosław
    Powiązania:
    https://bibliotekanauki.pl/articles/27311921.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    5G
    radio access networks
    packet-switched xHaul
    latency-sensitive network
    network slicing
    traffic prioritization
    network optimization
    Opis:
    Packet-switched xHaul networks are a scalable solution enabling convergent transport of diverse types of radio data flows, such as fronthaul / midhaul / backhaul (FH / MH / BH) flows, between remote sites and a central site (hub) in 5G radio access networks (RANs). Such networks can be realized using the cost-efficient Ethernet technology, which enhanced with time-sensitive networking (TSN) features allows for prioritized transmission of latency-sensitive fronthaul flows. Provisioning of multiple types of 5G services of different service requirements in a shared network, commonly referred to as network slicing, requires adequate handling of transported data flows in order to satisfy particular service / slice requirements. In this work, we investigate two traffic prioritization policies, namely, flowaware (FA) and latency-aware (LA), in a packet-switched xHaul network supporting slices of different latency requirements. We evaluate the effectiveness of the policies in a networkplanning case study, where virtualized radio processing resources allocated at the processing pool (PP) facilities, for two slices related to enhanced mobile broadband (eMBB) and ultra-reliable low latency communications (URLLC) services, are subject to optimization. Using numerical experiments, we analyze PP cost savings from applying the LA policy (vs. FA) in various network scenarios. The savings in active PPs reach up to 40% − 60% in ring scenarios and 30% in a mesh network, whereas the gains in overall PP cost are up to 20% for the cost values assumed in the analysis.
    Źródło:
    International Journal of Electronics and Telecommunications; 2023, 69, 2; 335--340
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ubiquity of Client Access in Heterogeneous Access Environment
    Autorzy:
    Gierłowski, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/308576.pdf
    Data publikacji:
    2014
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    handover
    mesh networks
    mobility
    technological networks
    ubiquitous access
    wireless networks
    Opis:
    With popularization of mobile computing and diverse offer of mobile devices providing functionality comparable to personal computers, the necessity of providing network access for such users cannot be disputed. The requirement is further reinforced by emergence of general purpose mobile operating systems which provide their full functionality only with network connectivity available and popular XaaS (Everything as a Service) approach. In this situation and combined with the fact that most Internet-based services are able to function efficiently even in best effort environment, requirement of ubiquity of network access becomes one of the most important elements of today’s computing environment. This paper presents a general overview of the the vast group of mechanisms and technologies utilized in modern attempts to efficiently provide ubiquity on network access in heterogeneous environment of today’s access systems. It starts with division of users interested in ubiquitous network access into broad groups of common interest, complete with their basic requirements and access characteristics, followed by a survey of both already popular and new wireless technologies suitable to provide such access. Then a general discussion of most important challenges which must be addressed while attempting to fulfill the above goal is provided, addressing topics such as handover control and mobility management.
    Źródło:
    Journal of Telecommunications and Information Technology; 2014, 3; 3-16
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Protocols for Wireless Sensor Networks: A Survey
    Autorzy:
    Kochhar, A.
    Kaur, P.
    Singh, P.
    Sharma, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/958098.pdf
    Data publikacji:
    2018
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    cross-layer
    Medium Access Control
    protocols
    Wireless Sensor Networks
    Opis:
    This paper presents a survey on the MAC and network layer of Wireless Sensor Networks. Performance requirements of the MAC layer are explored. MAC layer protocols for battery-powered networks and energy harvesting-based networks are discussed and compared. A detailed discussion on design constraints and classification of routing protocols is presented. Several routing protocols are compared in terms of such parameters as: energy consumption, scalability, network lifetime and mobility. Problems that require future research are presented. The cross-layer approach for WSNs is also surveyed.
    Źródło:
    Journal of Telecommunications and Information Technology; 2018, 1; 77-87
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simulating capture behaviour in 802.11 radio modems
    Autorzy:
    Ware, C.
    Wysocki, T. A.
    Chicharo, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/309552.pdf
    Data publikacji:
    2001
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    wireless local area networks
    ad hoc networks
    capture models
    medium access control protocol
    fairness
    Opis:
    Simulation plays an important role in the performance evaluation of MAC protocols. Building simulation models which are able to accurately model physical behaviour is fundamental to the outcome of such techniques. Through both qualitative and quantitative comparison of experimental trace data against simulation results obtained using delay, power, and hybrid capture models, this paper investigates the performance of various packet capture models in the simulation analysis of the 802.11 PHY and MAC layer protocols. We illustrate these models are unable to accurately describe the fairness properties of the experimental data. A new model is proposed, Message Retraining, to describe the operation of an 802.11 receiver. We illustrate that the Message Retraining reception model is able to model the fairness characteristics obtained with an IEEE 802.11 radio modem more accurately than the previous capture models.
    Źródło:
    Journal of Telecommunications and Information Technology; 2001, 3; 46-54
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    How the Role-Based Trust Management Can Be Applied to Wireless Sensor Networks
    Autorzy:
    Felkner, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/307588.pdf
    Data publikacji:
    2012
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    access control
    role-based trust management
    trust
    wireless sensor networks
    Opis:
    Trust plays an important role in human life environments. That is why the researchers has been focusing on it for a long time. It allows us to delegate tasks and decisions to an appropriate person. In social sciences trust between humans was studied, but it also was analyzed in economic transactions. A lot of computer scientists from different areas, like security, semantic web, electronic commerce, social networks tried to transfer this concept to their domains. Trust is an essential factor in any kind of network, whether social or computer. Wireless sensor networks (WSN) are characterized by severely constrained resources, they have limited power supplies, low transmission bandwidth, small memory sizes and limited energy, therefore security techniques used in traditional wired networks cannot be adopted directly. Some effort has been expended in this fields, but the concept of trust is defined in slightly different ways by different researchers. In this paper we will show how the family of Role-based Trust management languages (RT) can be used in WSN. RT is used for representing security policies and credentials in decentralized, distributed access control systems. A credential provides information about the privileges of users and the security policies issued by one or more trusted authorities.
    Źródło:
    Journal of Telecommunications and Information Technology; 2012, 4; 70-77
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ranking of LTE cells based on key performance indicators using MCDM methods
    Autorzy:
    Lopes Neto, Pedro Nunes
    Freire Junior, José Celso
    Tuna, Celso Eduardo
    Powiązania:
    https://bibliotekanauki.pl/articles/2211970.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet Ekonomiczny w Katowicach
    Tematy:
    long-term evolution
    multiple criteria methods
    radio access network performance management
    self-organizing networks
    Opis:
    The growth in worldwide data traffic and user subscriptions in mobile telecommunication networks makes it increasingly difficult to manage network performance in an environment already containing multiple radio access technologies. Despite the rise of 5G, LTE remains the dominant technology, and new cells are installed daily to support traffic growth and new services such as voice over LTE. Detecting faulty cells in the network is one of the main concerns of operators. Self organizing networks have been introduced to deal with this problem, and their self healing functionality has improved cell fault management. Nonetheless, faulty cell detection remains challenging, and most of the tasks involved are still done manually. This paper introduces a new method of faulty cell detection in an LTE radio access network, applying multiple criteria methods to this problem. The cells are ranked based on selected key performance indicators, using the multi attribute utility theory to construct a utility function. The analytic hierarchy process is used to define weights for the criteria.
    Źródło:
    Multiple Criteria Decision Making; 2022, 17; 46-68
    2084-1531
    Pojawia się w:
    Multiple Criteria Decision Making
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analyses of Code Division Multiple Access (CDMA) Schemes for Global Mobile Satellite Communications (GMSC)
    Autorzy:
    Ilcev, D. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1841573.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
    Tematy:
    Global Mobile Satellite Communications
    Code Division Multiple Access
    Multiple Access Technique
    Satellite Communication Systems
    Mobile Earth Station
    orthogonal channels of transmission
    GMSC Networks
    very small aperture terminals
    Opis:
    This paper describes in particular Code Division Multiple Access (CDMA) applicable in Global Mobile Satellite Communications (GMSC). In satellite communication systems, as a rule, especially in GMSC networks many users are active at the same time. The problem of simultaneous communications between many single or multipoint mobile satellite users, however, can be solved by using Multiple Access Technique (MAT) system. Since the resources of the systems such as the transmitting power and the bandwidth are limited, it is advisable to use the channels with complete charge and to create a different MAT to the channel. This generates a problem of summation and separation of signals in the transmission and reception parts, respectively. Deciding this problem consists in the development of orthogonal channels of transmission in order to divide signals from various users unambiguously on the reception part.
    Źródło:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2020, 14, 4; 805-810
    2083-6473
    2083-6481
    Pojawia się w:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evolutionary paths in wireless communication systems
    Autorzy:
    Michalski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/309042.pdf
    Data publikacji:
    2005
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    cellular mobile radio systems
    wireless local area networks
    wireless personal networks
    wide area wireless packet data systems
    satellite-based mobile systems
    paging/messaging systems
    cordless telephones
    access points
    switches
    GPRS
    Mobile IP
    WLAN cellular integration
    Opis:
    The paper contains a review and analysis of evolutionary paths of seven most important, from network development strategy point of view, wireless communication systems, especially the WLAN operating according to the IEEE 802.11 standard. With respect to WLAN, trends related to evolution toward mobile network and self organizing network as well as toward integration of WLAN and GSM using GPRS are presented. Concerning WLAN architecture development, evolution paths toward distributed controlled network as well as centrally coordinated and controlled network are described. Moreover, analysis includes cellular mobile radio systems, wireless personal networks, wide area wireless packet data systems, satellite-based mobile systems, paging/messaging systems and cordless telephones. With respect to these systems, general evolution process and trends associated with this process are described.
    Źródło:
    Journal of Telecommunications and Information Technology; 2005, 3; 105-111
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Development of models to study traffic accidents on the final sections of access roads to the cities: a case study of three major Iranian cities
    Autorzy:
    Fallah Tafti, Mehdi
    Roshani, Reza
    Powiązania:
    https://bibliotekanauki.pl/articles/1955155.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    traffic accidents
    city access roads
    entrance roads
    traffic safety
    accident prediction model
    neural networks
    wypadki drogowe
    drogi dojazdowe do miasta
    drogi wjazdowe
    bezpieczeństwo na drodze
    modele przewidywania wypadków
    sieci neuronowe
    Opis:
    The final sections of main access roads to the cities require especial attention as the frequency of accidents in these road sections are considerably higher than other parts of interurban roads. These road sections operate as an interface between the rural roads and urban streets. The previous researches available on this subject are limited and they have also mainly focused on a narrow range of factors contributing to the accidents in these areas. The main contribution of this research is to consider a relatively comprehensive range of potential factors , and to examine their impacts through the development and comparison of both conventional probabilistic models and Artificial Neural Network (ANN) models. For this purpose, information related to the main access roads of three major Iranian cities were collected. This information consisted of accident frequency data together with the field observations of traffic characteristics, roadway conditions and roadside features of these roads. Various ANN and probabilistic models were developed. The frequency of accidents, i.e. fatal, injured, or damaged accidents, was considered as the output of the developed models. The results indicated that a hybrid of ANN models, each comprised of 10 input variables representing traffic, roadway and roadside conditions, outperformed several probabilistic models, i.e. Poisson, Negative binomial, Zero-truncated Poisson, and Zero-truncated Negative Binomial models, also developed under similar conditions in this study. Moreover, effective roadway width, roadway lighting condition, the standard deviation of vehicles speed, percentage of drivers violating the speed limit, average annual daily traffic, percentage of heavy goods vehicles, the density of roadside commercial and industrial land uses, the density of median U-turns, the density of local access roads, and the effective width of the left-side shoulder were identified as the most effective factors contributing to the accidents in these areas. The developed ANN model can be used as a tool to predict accident rates in these road sections, and to estimate a potential reduction in the accident rates, following any improvements in the major factors contributing to the traffic accidents in these areas.
    Źródło:
    Archives of Transport; 2021, 59, 3; 129-148
    0866-9546
    2300-8830
    Pojawia się w:
    Archives of Transport
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Expected volumes of requests in systems of the queueing network with a limited number of waiting places
    Autorzy:
    Zając, P.
    Matalytski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/121834.pdf
    Data publikacji:
    2017
    Wydawca:
    Uniwersytet Humanistyczno-Przyrodniczy im. Jana Długosza w Częstochowie. Wydawnictwo Uczelniane
    Tematy:
    sieci HM
    sieci kolejkowe
    system kolejkowy
    bezprzewodowy punkt dostępu
    HM-networks
    queueing network
    single-line queueing system
    queueing system
    queuing time
    limited queue
    demands total volume
    wireless access point
    volume of requests
    Opis:
    We present a method of finding the expected volume of requests in HM-network with homogeneous requests and bypass of the queueing systems of requests. The case was considered when the volume changes associated with the transitions between the states of the network are deterministic functions, depending on the state of the network and time, and the systems are single line. It is assumed that the probability of the states of the network systems, the parameters of the entrance flow of the requests and the service depend on the time.
    Źródło:
    Scientific Issues of Jan Długosz University in Częstochowa. Mathematics; 2017, 22; 141-160
    2450-9302
    Pojawia się w:
    Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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