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Search results for: MULTIPATH ROUTING
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Multipath routing for quality of service differentiation and network capacity optimization in broadband low-earth orbit systems
PublicationThis paper shows the importance of employing multiple different paths for routing in Inter-Satellite Link (ISL) networks in broadband Low-Earth Orbit (LEO) satellite systems. A theoretical analysis is presented and a routing concept is proposed to demonstrate three facts that make multipath routing especially important in broadband LEO networks: (1) differences in the propagation delays have a much greater impact on end-to-end...
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Multipath Complex Root Tracing
PublicationThe problem of multipath root tracing is being addressed in this communication. The self-adaptive complex root tracing algorithm, which was previously utilized for the investigation of various propagation and radiation problems, is analyzed here for the cases when the traced characteristic bifurcates. A procedure of multiroute detection is proposed and demonstrated on the coaxially loaded cylindrical waveguide example.
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The lubricant-coating interaction in rolling and sliding contacts
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Hyperbolic position location estimation in the multipath propagation environment
PublicationThe efficiency analysis a hyperbolic position location estimation in the multipath propagation environment in the wideband code division multiple access (WCDMA) interface was presented. Four, the most popular methods: Chan's, Foy's, Fang's and Friedlander's were considered. These algorithms enable the calculation of the geographical position of a mobile station (MS) using the time differences of arrival (TDOA) between several base...
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Robustified estimators of radar elevation angle using a specular multipath model
PublicationWe consider the problem of estimating the elevation angle in the presence of multipath. The proposed method belongs to the class of maximum likelihood-like estimators and employs a modified specular reflection model that accounts for the uncertainty of the steering vector by assuming that they are subject to unknown deterministic perturbations with bounded norms. The analysis, performed using convex optimization methods, allows...
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Reduction of the Multipath Propagation Effect in a Hydroacoustic Channel Using Filtration in Cepstrum
PublicationDuring data transmission in a hydroacoustic channel, one of the problems is the multipath propagation effect, which leads to a decrease in the transmission parameters and sometimes completely prevents it. Therefore, we have attempted to develop a method, which is based on a recorded hydroacoustic signal, that allows us to recreate the original (generated) signal by eliminating the multipath effect. In our method, we use cepstral...
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Comparison of Doppler Effect Estimation Methods for MFSK Transmission in Multipath Hydroacoustic Channel
PublicationUnderwater wireless communication remains a challenging topic, particularly for applications such as wreck penetration where multipath and Doppler effects are very intense. These effects are becoming even more difficult to mitigate for fast data transmission systems that utilize wideband signals. Due to the low propagation speed of acoustic wave in the water, there is a significant difference between the Doppler shift for lower...
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Quantum channel capacities: multiparty communication
PublicationAnalizowane są różne aspekty wieloużytkownikowej komunikacji kwantowymi kanałami bez pamięci. Uogólnione zostały pewne znane rezultaty dotyczące komunikacji kwantowej w układzie jeden nadawca -jeden odbiorca. W szczególności pokazana została bezużyteczność komunikacji klasycznej ''w przód'' w procesie transmisji informacji kwantowej oraz równoważność definicji regionów pojemności opartych na różnych miarach wierności transmisji:...
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Numerical Simulation of Duplex Steel Multipass Welding
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Nonadditivity of quantum capacity for multiparty communication channels.
PublicationZbadano scenariusze komunikacji pomiędzy wieloma stronami gdzie informacje są przesyłane od wielu nadawców do wielu odbiorców.
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Taxonomy of Schemes for Resilient Routing
PublicationThis chapter provides a taxonomy of schemes for resilient routing followed by a discussion of their application to contemporary architectures of communication networks. In particular, a general classification of schemes for resilient routing is first presented followed by a description of the reference schemes for IP networks. The chapter in its later part focuses on the representative techniques of resilient routing for a multi-domain...
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Optimal routing in a transportation network
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Path Coloring and Routing in Graphs.
PublicationW rozdziale omówione zostały problemy kolorowania ścieżek i routingu w grafach. Podano podstawowe definicje związane z tymi problemami, znane wyniki wraz z dyskusją złożoności obliczeniowej dla grafów ogólnych i dla kilku podstawowych klas grafów oraz zastosowania.
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Resilient Routing in Communication Networks
PublicationThis important text/reference addresses the latest issues in end-to-end resilient routing in communication networks. The work highlights the main causes of failures of network nodes and links, and presents an overview of resilient routing mechanisms, covering issues related to the Future Internet (FI), wireless mesh networks (WMNs), and vehicular ad-hoc networks (VANETs). For each of these network architectures, a selection of...
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Clonal selection algorithm for vehicle routing
PublicationOver the years several successful computing techniques have been inspired by biological mechanisms. Studies of the mechanisms that allow the immune systems of vertebratesto adapt and learn have resulted in a class of algorithms called artificial immune systems. Clonal selection is a process that allows lymphocytes to launch a quick response to known pathogens and to adapt to new, previously unencountered ones. This paper presents...
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A Novel Reliable Routing Scheme for VANETs
PublicationSieci bezprzewodowej transmisji informacji bazujące na rodzinie standardów 802.11, zastosowane w przypadku komunikacji między pojazdami (VANET), mogą istotnie przyczynić się do poprawy bezpieczeństwa ruchu drogowego. Z uwagi na wysoki stopień mobilności pojazdów, dobór tras w sieciach VANET jest problemem trudnym, zwłaszcza w przypadku transmisji wieloskokowej. Rozwiązania dostępne w literaturze ukierunkowane na poprawę dostępności...
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Resonance Frequency Calculation of a Multilayer and Multipatch Spherical Microstrip Structure Using a Hybrid Technique
PublicationThis communication offers a rigorous analysis of the resonance frequency problem of a spherical microstrip structure mounted on a multilayer, dielectric-coated metallic sphere, with an electrically small radius. The structure consists of single or multiple metallic patches with arbitrary shapes. A full-wave analysis is employed with the use of proposed hybrid approach, combining the finite-difference technique with a spectral domain...
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An Analysis of Elliptical-Rectangular Multipatch Structure on Dielectric-Coated Confocal and Nonconfocal Elliptic Cylinders
PublicationA rigorous analysis of the resonance frequency problem of an elliptical-rectangular microstrip structure mounted on dielectric-coated elliptic conducting cylinder, with electrically small radius, is investigated in this paper. A full-wave analysis and a moment-method calculation are employed. The analysis is carried out considering the expansion of the field as a series of Mathieu functions. The complex resonance frequencies of...
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An Analysis of Probe-Fed Rectangular Patch Antennas With Multilayer and Multipatch Configurations on Cylindrical Surfaces
PublicationA multi-patch configuration of probe-fed rectangular microstrip antennas mounted on a cylindrical body, with electrically small radius, with an arbitrary number of substrate and superstrate layers is investigated in this paper. A full-wave analysis and a moment-method calculation are employed. A unified procedure for creating proper matrices for the investigated geometry of the structure is outlined here. Numerical results for...
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Trade-offs in multiparty Bell-inequality violations in qubit networks
PublicationTwo overlapping bipartite binary input Bell inequalities cannot be simultaneously violated as this would contradict the usual no-signalling principle. This property is known as monogamy of Bell inequality violations and generally Bell monogamy relations refer to trade-offs between simultaneous violations of multiple inequalities. It turns out that multipartite Bell inequalities admit weaker forms of monogamies that allow for violations...
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Performance of the Direct Sequence Spread Spectrum Underwater Acoustic Communication System with Differential Detection in Strong Multipath Propagation Conditions
PublicationThe underwater acoustic communication (UAC) operating in very shallow-water should ensure reliable transmission in conditions of strong multipath propagation, significantly disturbing the received signal. One of the techniques to achieve this goal is the direct sequence spread spectrum (DSSS) technique, which consists in binary phase shift keying (BPSK) according to a pseudo-random spreading sequence. This paper describes the DSSS...
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Multi-objective weather routing of sailing vessels
PublicationThe paper presents a multi-objective deterministic method of weather routing for sailing vessels. Depending on a particular purpose of sailboat weather routing, the presented method makes it possible to customize the criteria and constraints so as to fit a particular user’s needs. Apart from a typical shortest time criterion, safety and comfort can also be taken into account. Additionally, the method supports dynamic weather data:...
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METHOD OF ROUTING SHIPS SAILING IN DEDICATED ENVIRONMENT
PublicationThe method for determining the suboptimal route of sailing vessels operating in a restricted area of the sea are proposed in the paper. The dynamics of the environment including weather conditions and speed characteristics of ships sailing are considered. As optimiza-tion criterion, measure sailing time T, and the number of maneuvers performed ω, are taken into account. An heuristic algorithm, and the appropriate application routing...
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Disaster-Resilient Routing Schemes for Regional Failures
PublicationLarge-scale natural disasters can have a profound effect on the telecommunication services in the affected geographical area. Hence, it is important to develop routing approaches that may help in circumventing damaged regional areas of a network. This prompted the development of geographically diverse routing schemes and also of disaster-risk aware routing schemes. A minimum-cost geodiverse routing, where a minimum geographical...
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EVOLUTIONARY MULTI–OBJECTIVE WEATHER ROUTING OF SAILBOATS
PublicationThe paper presents a multi-objective method, which optimises the route of a sailboat. The presented method makes use of an evolutionary multi-objective (EMO) algorithm, which performs the optimisation according to three objective functions: total passage time, a sum of all course alterations made during the voyage and the average angle of heel. The last two of the objective functions reflect the navigator’s and passenger’s comfort,...
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Towards Improving Optimised Ship Weather Routing
PublicationThe aim of the paper is to outline a project focusing on the development of a new type of ship weather routing solution with improved uncertainty handling, through better estimation of ship performance and responses to sea conditions. Ensemble forecasting is considered to take into account the uncertainty levels that are typical of operations in a stochastic environment. Increased accuracy of weather prediction is achieved through...
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Routing equal-size messages on a slotted ring
PublicationAnalizujemy problem routingu wiadomości w sieci slotted ring, biorąc pod uwagę dwa kryteria optymalizacyjne: długość uszeregowania oraz liczbę 'cykli' pracy sieci. Optymalny routing dla wiadomości o rozmiarze k jest silnie NP-trudny, natomiast dla k=q, gdzie q jest rozmiarem sieci, można obliczyć w czsie O(n^2log n) dla pierwszego kryterium. Podajemy również algorytm o czasie działania O(nlog n) oraz o stałym współczynniku dobroci....
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Simulation model for evaluation of QOS dynamic routing
PublicationCurrent informational networks use a large variety of technologies to support data exchange. Most of them are focused on IP protocol and include mechanisms which by definition should supply demanded QoS. One of those mechanisms is efficient path calculation - routing. Traffic offered to the network can change very rapidly in short term. Routing should support such traffic changes and all the time calculate valid paths in terms...
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Multicriteria Evolutionary Weather Routing Algorithm in Practice
PublicationThe Multicriteria Evolutionary Weather Routing Algorithm (MEWRA) has already been introduced by the author on earlier TransNav 2009 and 2011 conferences with a focus on theoretical application to a hybrid-propulsion or motor-driven ship. This paper addresses the topic of possible practical weather routing applications of MEWRA. In the paper some practical advantages of utilizing Pareto front as a result of multicriteria optimization...
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A distributed scheme for inter-domain routing optimization
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Collision Risk-Informed Weather Routing for Sailboats
PublicationSelected COLREG rules, good seamanship and sheer common sense indicate that it is in a sailboat's interest to follow collision-free routes without relying on large power-driven ships to give way. Until now, however, no method has integrated a sailboat's weather routing with collision risk monitoring and collision avoidance. Therefore, a new deterministic approach to combine the above features within one method is introduced here....
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A multirate approach to DDS algorithm versus Taylor-series expansion technique.
PublicationPokazano, że cyfrowy generator syntezy bezpośredniej (DDS) można traktować jako algorytm wieloszybkościowy. Rozważono i porównano dwa sposoby wykorzystania pamięci. W pierwszym z nich zastosowano filtr ułamkowo-opóźniający o strukturze Farrowa. Drugie podejście oparto na rotacji fazy na podstawie rozwinięcia w szereg Taylora. Eksperymenty pokazują, że za pomocą obu tych sposobów, dla sinusoidy zespolonej generowanej w kwadraturowym...
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Toward Fast Calculation of Communication Paths for Resilient Routing
PublicationUtilization of alternate communication paths is a common technique to provide protection of transmission against failures of network nodes/links. However, a noticeable delay is encountered when calculating the relevant sets of disjoint paths using the available algorithms (e.g., using Bhandari’s approach). This, in turn, may have a serious impact on the ability of a network to serve dynamic demands...
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REVIEW OF WEATHER FORECAST SERVICES FOR SHIP ROUTING PURPOSES
PublicationWeather data is nowadays used in a variety of navigational and ocean engineering research problems: from the obvious ones like voyage planning and routing of sea-going vessels, through the analysis of stability-related phenomena, to detailed modelling of ships’ manoeuvrability for collision avoidance purposes. Apart from that, weather forecasts are essential for passenger cruises and fishing vessels that want to avoid the risk...
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Inverse Flood Routing Using Simplified Flow Equations
PublicationThe paper considers the problem of inverse flood routing in reservoir operation strategy. The aim of the work is to investigate the possibility of determining the hydrograph at the upstream end based on the hydrograph required at the downstream end using simplified open channel flow models. To accomplish this, the linear kinematic wave equation, the diffusive wave equation and the linear Muskingum equation are considered. To achieve...
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Reliable Anycast and Unicast Routing: Protection against Attacks
PublicationObecne sieci są przeważnie chronione przed awariami losowymi, a topologie sieci są w większości uznawane za regularne. Znane mechanizmy ochrony dotyczą typowo transmisji unicast (jeden-do-jednego). Jednakże w związku z obserwowaną konwergencją technologii/usług, inne odmiany transmisji (np. anycast - jeden-do-jednego-z-wielu) nabierają znaczenia. Co więcej, okazuje się, iż często awarie nie mają losowego charakteru, a topologie...
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Mass and momentum conservation in the simplified flood routing models
PublicationW pracy wykazano, że uproszczone modele fal wezbraniowych w postaci fali kinematycznej reprezentują w przypadku liniowych zarówno zasadę zachowania masy jaki i pędu, natomiast w przypadku nieliniowym, reprezentują albo zasadę zachowania masy albo pędu, zależnie od postaci zachowawczej równania. Ponadto wykazano, iż nieliniowa fala dyfuzyjna nie spełnia ani całkowowej zasady zachowania masy ani pędu.
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Selected Multi-Criteria Green Vehicle Routing Problems
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Survivability function - a measure of disaster-based routing performance.
PublicationZnaczenie przeżywalności sieci transmisji danych systematycznie rośnie, ponieważ awaria pojedynczego elementu może dotknąć miliony użytkowników na dużym obszarze. Zdefiniowano funkcję przeżywalności: prawdopodobieństwo realizacji określonego procentu strumieni użytkowników po awarii oraz atrybuty przeżywalności. Celem pracy było zbadanie wpływu protokołów doboru tras architektury TC/IP na funkcję i atrybuty przeżywalności. Pracę...
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Multi-objective Weather Routing with Customised Criteria and Constraints
PublicationThe paper presents a weather routing algorithm utilising a multi-objective optimisation with constraints, namely the Multi-objective Evolutionary Weather Routing Algorithm (MEWRA). In the proposed approach weather route recommendations can be made simultaneously e.g. for passage time, fuel consumption and safety of passage by means of Pareto optimisation. The sets of criteria and constraints in the optimisation process are fully...
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Cooperative multi-provider routing optimization and income distribution
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Traffic routing in the Warsaw metropolitan network: a deployment strategy
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Traffic Type Influence on Performance of OSPF QoS Routing
PublicationFeasibility studies with QoS routing proved that the network traffic type has influence on routing performance. In this work influence of self-similar traffic for network with DiffServ architecture and OSPF QoS routing has been verified. Analysis has been done for three traffic classes. Multiplexed ON-OFF model was used for self-similar traffic generation. Comparison of simulation results were presented using both relative and...
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Traffic Type Influence on Performance of OSPF QoS Routing
PublicationFeasibility studies with QoS routing proved that the network traffic type has influence on routing performance. In this work influence of self-similar traffic for network with DiffServ architecture and OSPF QoS routing has been verified. Analysis has been done for three traffic classes. Multiplexed On-Off model was used for self-similar traffic generation. Comparison of simulation results was presented using both relative and non-relative...
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A digital implementation of the PSK transmitter and receiver as multirate algorithms of the digital signal processing
PublicationIn this paper designs of the transmitter and the receiver of PSK signals as three-rate algorithms of the digital signal processing are described. Additionally we show the examples of the transmitter and the receiver of the following signals: BPSK, QPSK. We discussed also an influence of the cascade of the shaping filter and the receiving filter on the intersymbol interference in the received complex envelope.W pracy opisano projektowanie...
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Multi-objective weather routing of sailboats considering wave resistance
PublicationThe article presents a method to determine the route of a sailing vessel with the aid of deterministic algorithms. The method assumes that the area in which the route is to be determined is limited and the basic input data comprise the wind vector and the speed characteristic of the vessel. Compared to previous works of the authors, the present article additionally takes into account the effect of sea waves with the resultant resistance...
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Approximation strategies for routing edge disjoint paths in complete graphs
PublicationPraca dotyczy problemu ścieżek krawędziowo rozłącznych w nieskierowanych grafach pełnych, dla którego podano nowe algorytmy przybliżone: 3.75-przybliżony (model off-line) i 6.47-przybliżony (model on-line). Stosując podobną metodologię, uzyskano algorytm 4.5-przybliżony (off-line) i 6-przybliżony (on-line) dla problemu routingu i kolorowania ścieżek w grafach pełnych.
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Dynamic unattended measurement based routing algorithm for diffServ architecture
PublicationDynamic routing is very important in terms of assuring QoS in today's packet networks especially for streaming and elastic services. Existing solutions dedicated to dynamic routing are often too complicated and seem to be not usable in real time traffic scenarios where transferred traffic may vary significantly. This was the main reason for research and new routing mechanism proposal which should apply to today's packet networks....
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Selective Protection for All-Optical Physical Impairment Constrained Routing
PublicationW przypadku sieci optycznych, zauważalna jest obecnie tendencja dążenia do transmisji całowicie optycznej (tz. bez konwersji O/E/O w węzłach tranzytowych). Jednakże w niedalekiej przyszłości, z uwagi na techniczne ograniczenia, niemożliwa będzie obsługa całości ruchu wyłącznie w dziedzinie optycznej. Operatorzy będą więc zainteresowani oferowaniem rozwiązań przejściowych implikujących przełączanie w dziedzinie optycznej jedynie...
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Appraisement of modifications in dynamic routing protocols to support the IPng Protocol
PublicationW pracy, biorąc pod uwagę dynamiczny proces migracji sieci IPv4 do nowej wersji protokołu IP, przedstawiono konieczność realizacji w Internecie nowych protokołów routingu dynamicznego lub adaptacji już istniejących do nowego protokołu IPng. W artykule przedstawiono sposoby dostosowania protokołów routingu dynamicznego RIP, OSPF, BGP do nowego protokołu IP. Oceniono wpływ w/w dostosowywania na zbieżność i skalowalność protokołów...