Wyniki wyszukiwania - Biblioteka Nauki

1

Wpływ zdolności konwersji oraz strategii rutingu na jakość obsługi oraz wykorzystanie sieci w OTN

100%

Derkacz J. , Kantor M.

Telekomunikacja Cyfrowa : technologie i usługi

|

2003

|

tom T. 5

7-15

PL

Artykuł omawia niektóre z głównych parametrów węzłów optycznej sieci transportowej wpływających na efektywne działania tego typu sieci. W szczególności zbadano wpływ konwersji i przydziału długości fali oraz metod rutingu na poziomie optycznym na prawdopodobieństwo odrzucenia żądania połączenia oraz na wykorzystanie łączy. Przedstawione rezultaty przeprowadzonych badań pokazują, czego się można było spodziewać, że im większe możliwości konwersji długości fali, tym lepsza efektywność działania sieci. Co jest jednak bardzo istotne, z punktu widzenia złożoności oraz kosztów elementów sieciowych, pełna konwersja nie jest jednak w większości przypadków konieczna dla efektywnego działania sieci optycznej. W artykule przedstawione zostały wyniki porównania kilku metod rutingu na poziomie ścieżek optycznych. Podsumowanie pracy stanowią wskazania dotyczące planowania sieci optycznych.

EN

The paper considers some of the key parameters of the optical transport network elements affecting the efficiency of such networks. The analysis took into consideration the effect of the wavelength conversion and wavelength assignment rules on the call rejection probability and link utilization. The results show, as it could be expected, that the higher wavelengths conversion capabilities the more effectively is the traffic served. What is important, from the point of view network elements complexity and cost, the full wavelength conversion capability is not necessary in most cases. A few optical level routing strategies were compared in the work as well. The summary of the work constitutes some guidelines concerning the optical network planning.

2

Przegląd protokołów routingu stosowanych w mobilnych sieciach ad-hoc

85%

Korzyński P.

Spektrum

|

2007

|

tom nr 4-5

XII-XVIII

PL

Potrzeba znalezienia mechanizmu, który zapewni prawidłowe działanie sieci bez ograniczania użytkownikom możliwości poruszania się przyczyniła się do zaprojektowania i wdrożenia różnego typu protokołów routingu. Z powodu braku możliwości bezpośredniego przeniesienia podobnych mechanizmów działających w sieciach przewodowych na grunt WLAN (Wiveless Local Area Network), protokoły te zaprojektowano od podstaw. W referacie zaprezentowano mechanizmy stosowane w sieciach WLAN typu ad-hoc do poszukiwania dróg wymiany danych oraz sposoby działania, zalety i wady protokołów proaktywnych (Table-Driven Routing Protocols) oraz reaktywnych (On-Demand Routing).

EN

Necessity to find a mechanism ensuring proper network functioning and not limiting users possibilities to move in it greatly contributed to design and implement routing protocols of different kinds. Because there were no possibilities of straight transferring similar mechanisms functioning in wire networks to Wireless Local Area Networks (WLAN), the protocols had to be designed from the very beginning. Presented are mechanisms used for searching data interchange ways in ad-hoc type WLAN networks and also working methods, advantages and disadvantages of Table-Driven Routing Protocols and On-Demand Routing ones.

3

Determination of optimised pick-up and drop-off locations in transport routing - a cost distance approach

85%

Hahn A. , Frühling W. , Schlüter J.

Transport Problems

|

2022

|

tom T. 17, z. 1

17--28

EN

With the emergence of dynamic passenger transport systems, such as demand-responsive transport (DRT) and ride-sharing without predetermined stop locations as used for static bus routes, accurate routing for these flexible door-to-door transport services is needed. Routing between two addresses requires the assignment of addresses to suitable, so-called snapping points as reference points on the road network. Therefore, many conventional routing machines use perpendicular distance to identify the nearest point on the road network. However, this technique tends to produce inaccurate results if the access to a building is not reachable from the road segment with the shortest perpendicular distance. We provide a novel approach to identify the access to buildings (paths) based on remote sensing data to obtain more reasonable stop locations for passenger transport. Multispectral images, OpenStreetMap data, and light detection and ranging (LiDAR) data were used to perform a cost distance analysis based on vegetation cover, building footprints, and the slope of the terrain to identify such optimised stop locations. We assumed that the access to buildings on the shortest route to the building’s entrance consists of little vegetation cover and minimal slope of the terrain; furthermore, the calculated path should not cross building footprints. Thus, snapping points on the road network can be determined based on the most likely path between a building and the road network. We validated our results based on a predetermined ideal snapping area considering different weightings for the parameters slope, vegetation, and building footprints. The results were compared with a conventional routing machine that uses perpendicular distance. This routing machine shows a validation rate of 81.4%, whereas the validation rate of our presented approach is as high as 90.3%. This new approach provides increased accuracy and better comfort for flexible passenger transport systems.

4

Sieci typu community networks i ich zastosowania

85%

Raif P. , Karcewicz J. , Sachenko A. , Kapczyński A. , Banasik A.

Zeszyty Naukowe. Organizacja i Zarządzanie / Politechnika Śląska

|

2008

|

tom z. 45

325-334

PL

W artykule opisano znane rodzaje bezprzewodowych sieci ad-hoc oraz przedstawiono pokrótce ich zastosowania. Przeprowadzono klasyfikację protokołów routingu stosowanych w sieciach tego rodzaju. Przedstawiono zasadę działania protokołu OLSR oraz stanowisko badawcze oraz wnioski z początkowych badań działania protokołu.

EN

The article presents known kinds of wireless ad-hoc computer networks and its applications. Presents classification of routing protocols used in such a networks, specification of OLSR protocol and testhed used in experiments with this protocol.

5

Routing z estymacją powiązańwęzłów sieci MANET

85%

Bryś R. , Grajewski P.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

|

2018

|

tom nr 8-9

646--649, CD

PL

Efektywność sieci MANET uzależniona jest od funkcjonowania w niej mechanizmu routingu rozpoznającego topologię sieci, a następnie zestawiającego trasy do węzłów, często w warunkach dużej dynamiki zmian topologii. Prowadzi to do częstych przerw łączności, a w efekcie do opóźnień i strat danych. W artykule przedstawiona została koncepcja routingu z estymacją powiązań pomiędzy węzłami sieci. Rozwiązanie to pozwoli na wcześniejszą reakcję routingu na zmiany topologii oraz podjęcie działań utrzymania ciągłości tras. W artykule przedstawiono również wyniki testów symulacyjnych.

EN

The MANET network efficiency largely depends on the routing mechanism. This mechanism recognizes network topology, and than sets the routes to nodes, often under high topology changes. It leads to communication interruptions and consequently to delays and data loss. The article presents the concept of routing with nodes connection prediction. This solution allows for early response to topology changes and to take action to maintain routes continuity. In article also are presented the results of the connections time measurements’ simulation tests.

6

Policy-Based Routing na przykładzie systemu Vyatta

85%

Żelasko D.

Przegląd Elektrotechniczny

|

2014

|

tom R. 90, nr 8

46-49

PL

W artykule tym przedstawiona została technika, która umożliwia administratorowi sieci definiowanie reguł routingu opierajacych sie˛ na informacjach zawartych w nagłówku pakietu. W odróżnieniu od klasycznych technik routing decyzje nie są podejmowane wyłącznie na podstawie adresu docelowego. Dzięki tej technice administrator ma możliwość samodzielnego kierowania ruchu sieciowego w oparciu o pewne samodzielnie zdefiniowane zasady. W artykule omówione zostały również inne techniki, które często mylone są z Policy-Based Routing (PBR). Przykład wykorzystania techniki PBR przedstawiony został z wykorzystaniem programowego routera Vyatta. Również oprogramowaniu Vyatta został poświęcony fragment artykułu tak aby możliwym było zrozumienie zaprezentowanego przykładu.

EN

In this article technique which provides to administrator ability of defining different routing rules based on information from packet header was presented. In contrast to the classical routing techniques decisions are not based only on the destination address. With this technique administrator has ability to self-manage network traffic routing on the basis of self-established rules. In this article also some other techniques were presented which are often mistaken with Policy-Based Routing technique (PBR). An example of use of PBR technique was presented on Vyatta software router. To make it easier to understand the example Vyatta router was also described in this article.

7

Niezawodność protokołów routingu

85%

Polak R. , Laskowski D.

Journal of KONBiN

|

2015

|

tom No. 3 (35)

51--62

PL

Artykuł porusza tematykę wpływu uszkodzeń i zmiennych dynamicznych na działanie protokołów routingu i w konsekwencji całej sieci. W tym celu zapoznano się z charakterystyką routingu oraz protokołów wewnątrz i międzydomenowych. Następnie zbudowano architekturę sieciową opartą o stos protokołów TCP/IP, w której utworzono trzy systemy autonomiczne, z wyróżnieniem szkieletu sieci. Wykonano testy niezawodnościowe polegające na odporności na narażenia fizyczne sieci i zmiany dynamiczne paramentów sieciowych oraz testy wydajnościowe.

EN

The article refers to the impact of damage and dynamic variables on operation of routing protocols and consequently to the whole network. On this purpose, there was introduced the characteristic of the routing protocols and both an internal and an exterior gateway. Then, it was built the network architecture based on the TCP / IP stack. In the stack, there were created three autonomous systems and one of them was the backbone of the network. What is more, reliability tests, which have been performed, consisted of a resistance to physical damage to the network and dynamically changing parameters of the network as well as performance tests.

8

Sub-optimal routing at computer communication networks with unreliable transmission channels

80%

Grzech A. , Kollek R.

Archiwum Informatyki Teoretycznej i Stosowanej

|

2001

|

tom T. 13, z. 4

375-387

EN

This paper is devoted to present an algorithm leading to sub-optimal solution of flow assignment task in packet-switched store-and forward communication network with unreliable communication channels. It is assumed that the sub-optimal flow may be determined based on optimal solution of flow assignment task at reliable network. It is further assumes that the knowledge of optimal flows in reliable network allows to obtain the sub-optimal flow in unreliable network in much shorter time, that time required to obtain optimal solution of flow assignment task in unreliable network. The shorter time and accuracy of the sub-optimal flow are trade-off factors of the assignment task. The quality of the sub-optimal solution depends of monitoring system supported the considered network; exactly it depends on monitoring system range, i.e., number of nodes among which the information about channel failures is distributed. Introduction of monitoring system is equivalent to possibility of dividing entire network into two sub-networks. Some simulation results illustrate the features of the proposed approach.

PL

Artykuł jest poświęcony prezentacji algorytmu prowadzącego do suboptymalnego rozwiązania przydziału strumienia zadaniom w sieciach komputerowych z przełączaniem pakietów typu zapamiętaj i prześlij z niewiarygodnymi kanałami transmisji. Założono, że prawie optymalny strumień może być określony w oparciu o optymalne rozwiązanie przydziału strumienia zadaniom w niezawodnych sieciach. Następnie założono, że wiedza o optymalnym przepływie w niezawodnych sieciach pozwala uzyskać suboptymalny strumień w sieciach niewiarygodnych w czasie krótszym niż czas wymagany do uzyskania optymalnego rozwiązania przydziału strumienia zadaniom w sieciach niewiarygodnych. Trzeba znaleźć kompromis pomiędzy dokładnością a czasem przydziału suboptymalnego strumienia. Jakość rozwiązania zależy od systemu monitorującego rozważaną sieć, a ściślej od zasięgu tego systemu, tzn. liczby węzłów, pomiędzy którymi jest rozpowszechniana informacja o błędach w kanale. Wprowadzenie systemu monitorującego jest jednoznaczne z możliwością podzielenia całej sieci na dwie podsieci. Cechy zilustrowanej aproksymacji zilustrowano wynikami kilku symulacji.

9

Ant colony optimization applied to the problem of choosing the best combination among m combinations of shortest paths in transparent optical networks

80%

Brasileiro Í. , Santos I. , Soares A. , Rabêlo R. , Mazullo F.

Journal of Artificial Intelligence and Soft Computing Research

|

2016

|

tom Vol. 6, No. 4

231--242

EN

This paper presents an attempt to solve the problem of choosing the best combination among the M combinations of shortest paths in optical translucent networks. Fixed routing algorithms demands a single route to each pair of nodes. The existence of multiple shortest paths to some pairs of nodes originates the problem of choose the shortest path which fits better the network requests. The algorithm proposed in this paper is an adaptation of Ant Colony Optimization (ACO) metaheuristic and attempt to define the set of routes that fits in an optimized way the network conditions, resulting in reduced number of blocked requests and better adjusted justice in route distribution. A performance evaluation is conducted in real topologies by simulations, and the proposed algorithm shows better performance between the compared algorithms.

10

Extending SSM to MIPv6 – problems, solutions and improvements

80%

Schmidt T. , Wählisch M.

Computational Methods in Science and Technology

|

2005

|

tom Vol. 11, nr 2

147-152

EN

Multicast data delivery carries distinct importance in mobile wireless environments, where bandwidth is limited and transmission channels are shared between users. The development of mobile multicast protocols consequently exhibits emerging interest. As the common approach of Any Source Multicast distribution is burdened with intricate routing procedures, the spread of multicast-enabled network infrastructure remains hesitant. I t is widely believed that simpler mechanisms for group distribution in Source Specific Multicast (SSM) will lead to a pervasive dissemination of multi-cast infrastructure and services. However, SSM is designed for the a priori known and changeless addresses of multicast sources and thus withstands any easy extension to mobility. This paper reviews the state-of-the-art in current work to extend SSM to Mobile IPv6 networks. The principle conceptual problems are discussed and analysed. Propositions for improvement and possible directions to proceed further in SSM source mobility are presented.

11

Socionomic Modelling in Wireless Sensor Networks

80%

Sinha S. , Chaczko Z.

International Journal of Electronics and Telecommunications

|

2011

|

tom Vol. 57, No. 3

301-308

EN

The performance and efficiency of a Wireless Sensor Network (WSN) is typically subject to techniques used in data routing, clustering, and localization. Being primarily driven by resource constraints, a Socionomic model has been formulated to optimize resource usage and boost collaboration among sensor nodes. In this paper, we present several experimental results to ascertain the underlying philosophy of the Socionomic model for improving network lifetime of resource constrained devices - such as, sensor nodes.

12

On the performance analysis of a heuristic approach dedicated to a multiobjective dynamic routing model

80%

Craveirinha J. , Martins L. , Climaco J. N. , Jorge L.

Journal of Telecommunications and Information Technology

|

2005

|

tom nr 3

14-23

EN

In previous works the features and a complete formulation for circuit-switched networks of a multiple objective dynamic routing method (MODR) of periodic state dependent routing type were presented. The aim of the model is to resolve a very complex network bi-objective dynamic routing problem, by recurring to a heuristic for synchronous path selection enabling to obtain a good compromise solution in terms of two network performance measures. In this paper we present a study on the performance of variants of the MODR heuristic of synchronous path selection by using relaxations of the values previously calculated for the two network objective functions. This study permitted the development of an improved version of the initial heuristic. Also a comparison of the analytical values of the network objective functions obtained with selected variants of the initial heuristic with the corresponding results from a known reference method, the real time network routing (RTNR) method, given by a discrete-event simulator for single-service networks, is presented.

13

Comparison of Multicast Algorithm Evaluation Results in Low and High Multicast Saturation Environments

80%

Stachowiak K. , Zwierzykowski P.

Journal of Telecommunications and Information Technology

|

2019

|

tom nr 3

3--7

EN

The multicast quality of service-enabled routing is a computationally challenging task. Despite ongoing research eﬀorts, the associated mathematical problems are still considered to be NP-hard. In certain applications, computational complexity of ﬁnding the optimal connection between a set of network devices may be a particularly diﬃcult challenge. For example, connecting a small group of participants of a teleconference is not much more complex than setting up a set of mutual point-to-point connections. On the other hand, satisfying the demand for such services as IPTV, with their receivers constituting the majority of the network, requires applying appropriate optimization methods in order to ensure real system execution. In this paper, algorithms solving this class of problems are considered. The notion of multicast saturation is introduced to measure the amount of multicast participants relative to the entire network, and the eﬃciency of the analyzed algorithms is evaluated for diﬀerent saturation degrees.

14

An Algorithm for Enumerating SRLG Diverse Path Pairs

80%

Gomes T. , Craveirinha J.

Journal of Telecommunications and Information Technology

|

2010

|

tom nr 3

5-12

EN

Telecommunication networks are intrinsically multi-layered, a single failure at a lower level usually corresponds to a multi-failure scenario at an upper layer. In this context, the concept of shared risk link group (SRLG) allows an upper layer to select, for a given active path (AP), a backup path (BP), which avoids every SRLG that may involve the selected AP, in the event of a failure. That is a SRLG diverse path set maybe defined as a set of paths, between an origin and a destination, such that no pair of paths can be simultaneously affected by any given failure (or risk) in a single failure scenario. Firstly we present the formulation of the SRLG di- verse path pair calculation problem in a directed network. An algorithm for enumerating SRLG diverse paths, by non decreasing cost of their total (additive) cost will be presented, which is based on an algorithm proposed for generating minimal cost node disjoint path pairs. The SRLG diverse path pairs may be node or arc disjoint, with or without length constraints. Computational results will be presented to show the efficiency of the proposed algorithm for obtaining node or arc disjoint SRLG diverse path pairs in undirected networks.

15

Fuzzy Clustering with Multi-Constraint QoS Service Routing in Wireless Sensor Networks

80%

Agarkhed J. , Kadrolli V. , Patil S. R.

Journal of Telecommunications and Information Technology

|

2019

|

tom nr 1

31--38

EN

This paper presents a fuzzy logic-based, service diﬀerentiated, QoS aware routing protocol (FMSR) oﬀering multipath routing for WSNs, with the purpose of providing a service diﬀerentiated path meant for communication between nodes, based on actual requirements. The proposed protocol initially forms a cluster by fuzzy c-means. Next, the building of a routing follows, so as to establish multiple paths between nodes through the modiﬁed QoS k-nearest neighborhood, based on diﬀerent QoS constraints and on optimum shortest paths. If one node in the path fails due to lack of residual energy, bandwidth, packet loss, delay, an alternate path leading through another neighborhood node is selected for communication. Simulation results show that the proposed protocol performs better in terms of packet delivery ratio, delay, packet drop ratio and throughput compared to other existing routing protocols.

16

A Survey on Efficient Routing Strategies for The Internet of Underwater Things (IoUT)

80%

Al-Bzoor M. , Ayyad W. , Altaani O.

International Journal of Electronics and Telecommunications

|

2022

|

tom Vol. 68. No. 4

825--830

EN

The Internet of Underwater Things (IoUT) is an emerging technology that promised to connect the underwater world to the land internet. It is enabled via the usage of the Underwater Acoustic Sensor Network (UASN). Therefore, it is affected by the challenges faced by UASNs such as the high dynamics of the underwater environment, the high transmission delays, low bandwidth, high-power consumption, and high bit error ratio. Due to these challenges, designing an efficient routing protocol for the IoUT is still a trade-off issue. In this paper, we discuss the specific challenges imposed by using UASN for enabling IoUT, we list and explain the general requirements for routing in the IoUT and we discuss how these challenges and requirements are addressed in literature routing protocols. Thus, the presented information lays a foundation for further investigations and futuristic proposals for efficient routing approaches in the IoUT.

17

Autonomous Navigation Control of UAV Using Wireless Smart Meter Devices

80%

Ueda K. , Miyoshi T.

Journal of Telecommunications and Information Technology

|

2019

|

tom nr 2

64--72

EN

In preparation for the upcoming home delivery services that rely on Unmanned Aerial Vehicles (UAVs), we developed a new multi-hop radio network that is laid over a smart meter network transferring electric energy information only. In this network, a UAV follows, for navigation purposes, the topology of a virtual network overlaid on the physical smart meter network. We established a service management control method which does not rely on image analysis or map information processing, i.e. processes that consume precious power resources of the UAV. Instead, navigation is based on the routing technology. The current distance between the UAV and a node of the smart meter network is measured by means of the radio transmission loss value, therefore determining the position of the UAV. A two-layer network model has been proposed. One layer consists of a network of nodes in a residential area with scattered buildings – a location that is safer to navigate – while the other is an access network of nodes in a densely populated area. Then, we proposed methods to determine the direction of movement towards the next hop node on the data-link layer and the end node on the network layer, which is the target destination. We implemented a software-based test system and veriﬁed the eﬀectiveness of the proposed methods.

18

A Comprehensive Survey on Routing and Security in Mobile Wireless Sensor Networks

80%

Al-Nasser A. , Almesaeed R. , Al-Junaid H.

International Journal of Electronics and Telecommunications

|

2021

|

tom Vol. 67, No. 3

483--496

EN

With the continuous advances in mobile wireless sensor networks (MWSNs), the research community has responded to the challenges and constraints in the design of these networks by proposing efficient routing protocols that focus on particular performance metrics such as residual energy utilization, mobility, topology, scalability, localization, data collection routing, Quality of Service (QoS), etc. In addition, the introduction of mobility in WSN has brought new challenges for the routing, stability, security, and reliability of WSNs. Therefore, in this article, we present a comprehensive and meticulous investigation in the routing protocols and security challenges in the theory of MWSNs which was developed in recent years.

19

The analytical modl of IP/MPLS network

80%

Olszewski I.

Image Processing & Communications

|

2009

|

tom Vol. 14, no 4

63-71

EN

In this paper, the analysis of multi-servicing IP network with Multi-Protocol Label Switching (MPLS) protocol based on the proposed analytical and simulation models has been carried out. In the models two classes of service with different QoS parameters have been analyzed: class High, responsible for example for the Premium service, and class Low services for transmission of data. In this paper the changes of packet delays and lengths of queues for the given class of services in the network were taken into account, depending on the changes of average packet lengths, load of the network and the amount of inelastic traffic in the whole traffic. The results obtained in this paper have proved, that proposed analytical model is useful for analysis of the IP networks with MPLS protocol.

20

Selected Issues of QoS Provision in Heterogenous Military Networks

80%

Hauge M. , Landmark L. , Łubkowski P. , Amanowicz M. , Maślanka K.

International Journal of Electronics and Telecommunications

|

2014

|

tom Vol. 60, No. 1

7-13

EN

Tactical ad-hoc networks are evolving today towards complex heterogeneous networks in terms of architecture, protocols and security. Due to the difference in network resources and reliability, end-to-end quality of service provisioning becomes very challenging. If we also take into account communication issues such as unpredictable connectivity, preferential forwarding for special traffic classes, intermittency due to node or communication link failure, the problem is further aggravated. In this article, we examine the major challenges that must be solved in order to provide efficient QoS provisioning in the heterogeneous network. Finally we describe QoS-aware mechanisms for inter-domain and intra-domain heterogeneous networks, also including real-time services provision in highly mobilr environments.