Temat: multipath - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Effects of Multipath and Conventional NMES on Maximum Comfortable Stimulus and Torque Production
Autorzy:: Bremner, Cody B.
Holcomb, William R.
Powiązania:: https://bibliotekanauki.pl/articles/1030629.pdf
Data publikacji:: 2018
Wydawca:: Uniwersytet Szczeciński. Wydawnictwo Naukowe Uniwersytetu Szczecińskiego
Tematy:: NMES
multipath
quadriceps
Opis:: A novel multipath NMES (m-NMES) device has shown improved outcomes relative to conventional NMES (c-NMES) during recent basic and training studies. However, the mechanisms by which m-NMES outperformed c-NMES remain unclear. This study aimed to better understand these mechanisms by comparing the effects of m-NMES and c-NMES on maximum comfortable stimulus intensity and the subsequent NMES-induced torque, as these variables ultimately impact NMES training intensity; which is considered to be the primary determinant of NMES effectiveness. We measured maximum comfortable stimulus intensity and the subsequent NMES-induced torque while participants performed NMES-induced contractions under two conditions (m-NMES and c-NMES). Maximum comfortable stimulus intensity was significantly greater under the m-NMES condition, but the subsequent NMES-induced torque was not significantly different across conditions. m-NMES does not appear to influence the outcomes in a clinically meaningful manner, since it performed similarly to c-NMES with respect to peak NMES-induced torque.
Źródło:: Central European Journal of Sport Sciences and Medicine; 2019, 25, 1; 23-33
2300-9705
2353-2807
Pojawia się w:: Central European Journal of Sport Sciences and Medicine
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Intra- and inter-cell interference investigations for broadband radio access systems above 10 GHz
Autorzy:: Bose, R.
Hayn, A.
Jakoby, R.
Powiązania:: https://bibliotekanauki.pl/articles/308404.pdf
Data publikacji:: 2001
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: multipath propagation
interchannel interference
Opis:: Local multipoint distribution systems (LMDS) operating above 10 GHz have a large bandwidth (2-3 GHz) but a very limited range. These systems can provide coverage to a few kilometers only. These systems can provide coverage to a few kilometers only. The size of the macro cells illuminated by the base stations, where line of sight (LOS) exists, is 1 to 6 km. To provide coverage to customers where LOS is not possible, repeaters or passive reflectors may be used. In this paper we present first results of reflection measurements at 42 GHz, and based on that, simple multipath studies, taking into account the beamwidth of the antennas of both, transmitter and receiver. Secondly, LOS cochannel and adjacent channel interference are assessed for cellular LMDS networks. As suggested in the CRABS report, the maximal spectral efficiency can be obtained with a dual frequency and polarization reuse plan. This frequency and polarization reuse leads to interference. In this paper we have first calculated the cochannel interference (CCI) and the adjacent channel interference (ACI) due to the frequency/polarization reuse schemes suggested in the CRABS report. The effects of the variation of the half power beam width (HPBW) of the receiver, the time precentage parameter p, and the cell radius on C/I are also reported. In the latter part of the paper we propose a simple interference reduction technique based on re-orientation of the receiver antennas. We have also explored the possibility of using trellis coded modulation (TCM) for reducing interference levels. Initial results have been found to be quite encouraging.
Źródło:: Journal of Telecommunications and Information Technology; 2001, 2; 10-20
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Empirical Seasons Fadings in Radio Communication at 6 GHz Band
Autorzy:: Bogucki, J.
Wielowieyska, E.
Powiązania:: https://bibliotekanauki.pl/articles/308892.pdf
Data publikacji:: 2009
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: line-of-sight radio links
multipath
propagation
Opis:: This paper covers unavailability of line-of-sight radio links due to multipath propagation. Multipath fading in the atmosphere is not permanent phenomenon. The five year investigation results of the received radio signal fading in the radio links and their season empirical distributions are presented.
Źródło:: Journal of Telecommunications and Information Technology; 2009, 2; 48-52
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Edge decompositions of multigraphs into multi-2-paths
Autorzy:: Kratochvil, J.
Lonc, Z.
Meszka, M.
Skupień, Z.
Powiązania:: https://bibliotekanauki.pl/articles/2050185.pdf
Data publikacji:: 2004
Wydawca:: Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:: edge decomposition
multigraph
multipath
path
time complexity
Opis:: We establish the computational time complexity of the existence problem of a decomposition of an instance multigraph into isomorphic 3-vertex paths with multiple edges. If the two edge multiplicities are distinct, the problem is NPC; if mutually equal then polynomial.
Źródło:: Opuscula Mathematica; 2004, 24, 1; 97-102
1232-9274
2300-6919
Pojawia się w:: Opuscula Mathematica
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Spectral analysis of multi-year GNSS code multipath time-series
Autorzy:: Kudrys, Jacek
Powiązania:: https://bibliotekanauki.pl/articles/390405.pdf
Data publikacji:: 2019
Wydawca:: Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:: GNSS
code multipath
spectral analysis
spectral index
Opis:: In the presented study multi-year time series of changes in the L1 pseudo-range multipath are analysed. Data from 8 stations of the EUREF Permanent Network (EPN) were used in the study. Periodic components present in the signal and their stability over time were analysed. Also, the type of background noise was determined, based on the spectral index. In some cases, the presence of weak components with a 1/2 and 1/3 of the Chandler period has also been found. Time-frequency analysis shows that periodic signals are not stationary in most of the examined cases, and particular signal components occur only temporarily. The analysed signals were char-acterised by pink noise in the lower frequency range and by white noise for higher frequencies, which is also characteristic for time series of coordinates obtained from GNSS measurements.
Źródło:: Budownictwo i Architektura; 2019, 18, 4; 15-22
1899-0665
Pojawia się w:: Budownictwo i Architektura
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Impacts of forest spatial structure on variation of the multipath phenomenon of navigation satellite signals
Autorzy:: Brach, Michał
Stereńczak, Krzysztof
Bolibok, Leszek
Kwaśny, Łukasz
Krok, Grzegorz
Laszkowski, Michał
Powiązania:: https://bibliotekanauki.pl/articles/2044153.pdf
Data publikacji:: 2019
Wydawca:: Instytut Badawczy Leśnictwa
Tematy:: GNSS
multipath
random forest
Borut
forest structure
LiDAR
Opis:: The GNSS (Global Navigation Satellite System) receivers are commonly used in forest management in order to determine objects coordinates, area or length assessment and many other tasks which need accurate positioning. Unfortunately, the forest structure strongly limits access to satellite signals, which makes the positioning accuracy much weak comparing to the open areas. The main reason for this issue is the multipath phenomenon of satellite signal. It causes radio waves reflections from surrounding obstacles so the signal do not reach directly to the GNSS receiver’s antenna. Around 50% of error in GNSS positioning in the forest is because of multipath effect. In this research study, an attempt was made to quantify the forest stand features that may influence the multipath variability. The ground truth data was collected in six Forest Districts located in different part of Poland. The total amount of data was processed for over 2,700 study inventory plots with performed GNSS measurements. On every plot over 25 forest metrics were calculated and over 25 minutes of raw GNSS observations (1500 epochs) were captured. The main goal of this study was to find the way of multipath quantification and search the relationship between multipath variability and forest structure. It was reported that forest stand merchantable volume is the most important factor which influence the multipath phenomenon. Even though the similar geodetic class GNSS receivers were used it was observed significant difference of multipath values in similar conditions.
Źródło:: Folia Forestalia Polonica. Series A . Forestry; 2019, 61, 1; 3-21
0071-6677
Pojawia się w:: Folia Forestalia Polonica. Series A . Forestry
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Fading duration in line-of-sight radio links at 6 GHz
Autorzy:: Bogucki, J.
Wielowieyska, E.
Powiązania:: https://bibliotekanauki.pl/articles/308731.pdf
Data publikacji:: 2013
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: fading
line-of-sight radio links
multipath
propagation
Opis:: Broadband fixed wireless access, local multipoint distribution service networks are promising wireless solutions to connect fixed users to the backbone network instead of wired copper or fiber optic networks, via point-to-multipoint cellular networks. Channel capacity is of primary importance in broadband fixed wireless access networks due to increasing demand for multimedia services and possibility of providing wireless internet. Modern radio transmission systems are specifically designed for meeting two main objectives: to provide a solution for long distance networks with high transmission capacity, and to guarantee the highest link quality. Availability of a radio-relay system is very important and dependent on many factors, particularly propagation conditions in the troposphere. The article describes wave propagation that determines the performance of a radio-relay path at 6 GHz. Attenuation of received signal level measured in this frequency range depends on propagation condition on terrestrial path. Examples of measured fading duration of are presented.
Źródło:: Journal of Telecommunications and Information Technology; 2013, 2; 14-18
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Pilot Agent-Driven Wireless Acoustic Sensor Network for Uninterrupted Data Transmission
Autorzy:: Ghosh, Utpal
Mondal, Uttam K.
Powiązania:: https://bibliotekanauki.pl/articles/27312943.pdf
Data publikacji:: 2023
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: agent technology
audio signal
multipath routing
partial topology
WASN
Opis:: Wireless acoustic sensor networks (WASN) usually demand uninterrupted and reliable data transmissions and an efficient path from the source nodes to the destination nodes, thus ensuring reliable delivery of sensitive or critical data with the use of multipath routing protocols. This paper presents a novel agent-driven WASN relying on a set of static and mobile agents. In the proposed technique, the location address is functioned into the operating node and the destination node. Calculations of the midpoint between the operating and the destination nodes are followed by identifying the shortest path based on a reference axis, using a mobile agent and a location address. Such an approach aims to ensure maximum utilization of the communicating paths. Based on the information concerning partial topology of the network, the destination node computes the weight factor and multiple paths using node distances, energy ratios and efficiencies of specific links. Then, the destination node selects the appropriate path from the multiple paths available, to transmit the data. This article also analyzes the performance of the proposed system with various parameters taken into consideration and shows its efficiency in comparison to other existing techniques.
Źródło:: Journal of Telecommunications and Information Technology; 2023, 4; 53--60
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: A Study of Wireless Sensor Networks to Comprehend their Relevance to Different Applications
Autorzy:: Agarkhed, Jayashree
Dattatraya, Patil Yogita
Patil, Siddarama
Powiązania:: https://bibliotekanauki.pl/articles/308904.pdf
Data publikacji:: 2020
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: clustering
energy efficiency
multipath-based routing
wireless sensor network
Opis:: Wireless sensor networks (WSNs) have experienced enormous growth, both in terms of the technology used and their practical applications. In order to understand the features of WSNs that make the solution suitable for a speciﬁc purpose, one needs to be aware of the theoretical concepts behind and technological aspects of WSNs. In this paper, the signiﬁcance of WSNs is illustrated, with a particular emphasis placed on their demands and on understanding researchrelated problems. A review of the literature available is presented as well. Detailed discussions concerning sensor node architecture, different types of sensors used and their relevance for various types of WSNs is presented, highlighting the need to achieve application-speciﬁc requirements without degrading service quality. Multipath and cluster-based routing protocols are compared in order to analyze QoS requirements they are capable of satisfying, and their suitability for different application areas is reviewed. This survey highlights the performance of different routing protocols, therefore providing guidelines enabling each of the routing techniques to be used, in an efficient manner, with factors such as speciﬁc network structure, protocol operation and routing path construction taken into consideration in order to achieve better performance.
Źródło:: Journal of Telecommunications and Information Technology; 2020, 2; 3-13
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Closed-form Distribution and Analysis of a Combined Nakagami-lognormal Shadowing and Unshadowing Fading Channel
Autorzy:: Singh, R.
Rawat, M.
Powiązania:: https://bibliotekanauki.pl/articles/309183.pdf
Data publikacji:: 2016
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: multipath shadowing fading
outage probability
propagation
wireless communication system
Opis:: The realistic wireless channels face combined (time shared) Nakagami-lognormal shadowing and unshadowing fading because of time varying nature of radio channel and mobile user. These channels can be modeled as time-shared sum of multipath-shadowing and unshadowing Rician distributions. These fading create severe problems in long distance wireless systems where multipath fading is superim-posed on shadowing fading (called multipath-shadowing fading). The multipath effect can be modeled using Rayleigh, Rician, Nakagami-m or Weibull distribution and shadowing effect is modeled using lognormal distribution. In this paper, authors present a new closed-form probability distribution function of a Nakagami-lognormal fading channel. Using this result, the closed-form expression of combined Nakagami-lognormal shadowing and unshadowing fading is presented. The obtained closed-form result facilitates to derive the important performance metrics of a communication system such as amount of fading, outage probability, and average channel capacity in closed-form expressions.
Źródło:: Journal of Telecommunications and Information Technology; 2016, 4; 81-87
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 11.

Tytuł:: Throughput Performance Comparison of MPT-GRE and MPTCP in the Fast Ethernet IPv4/IPv6 Environment
Autorzy:: Szilágyi, S.
Fejes, F.
Katona, R.
Powiązania:: https://bibliotekanauki.pl/articles/307712.pdf
Data publikacji:: 2018
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: channel capacity aggregation
MPTCP
MPT-GRE
multipath communication
performance analysis
tunneling
Opis:: This paper presents the MPT-GRE software, a novel multipath communication technology founded on the Generic Routing Encapsulation (GRE) protocol in UDP tunneling RFC speciﬁcation. It enables the creation of a GRE protocolbased UDP tunnel built on several communication channels. On the other hand, MPTCP is one of the most typical representatives among multipath communication technologies, basing its operation on the utilization of TCP subﬂows. The authors compare the path-aggregation capabilities of these two technologies using four Fast Ethernet channels. The tests were carried out with the iperf3 network bandwidth measurement tool, and while transferring data using the FTP protocol over both IPv4 and IPv6.
Źródło:: Journal of Telecommunications and Information Technology; 2018, 2; 53-59
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 12.

Tytuł:: Coverage Improvements for Sub-Terahertz Systems Under Shadowing Conditions
Autorzy:: Mohr, Werner
Powiązania:: https://bibliotekanauki.pl/articles/24200742.pdf
Data publikacji:: 2023
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: multipath propagation
radio range
received power
reconfigurable intelligent surface
RIS
shadowing
Opis:: Radio propagation in the millimeter wave and sub-terahertz domain is heavily affected by shadowing conditions. The communication link is blocked without any additional technical means being used. Coverage improvements can be provided by using reflectors, RIS arrays, and repeaters to direct radio waves around corners or obstacles. These concepts show different performance and complexity levels affecting their network deployment. This paper investigates the achievable radio range or the received power to compare specific deployment concepts under realistic propagation conditions. Overall, the repeater solution provides either the largest radio range or the lowest necessary total transmit power compared to reflectors or RIS arrays and, thereby, is the most sustainable approach. A RIS array requires an additional centralized signal processing capacity for calculating optimized RIS settings and results in the highest level of network deployment complexity.
Źródło:: Journal of Telecommunications and Information Technology; 2023, 3; 1--10
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 13.

Tytuł:: DiffServ Aware MPLS Traffic Engineering for ISP Networks: State of the Art and New Trends
Autorzy:: Toguyéni, A.
Korbaa, O.
Powiązania:: https://bibliotekanauki.pl/articles/308811.pdf
Data publikacji:: 2009
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: differentiated service
multipath routing
QoS routing
quality of service
traffic engineering
Opis:: In the recent ten years, with the development of new applications through Internet such as multimedia or networked control applications, users need more and more quality of service (QoS). However, the requested QoS is not the same depending on the application. Most of the new models to manage internet traffic are based on specific QoS criteria which should be optimized. This paper presents main multiprotocol label switching (MPLS) approaches such as MPLS adaptive traffic engineering (MATE), load distribution in MPLS (LDM) and load balancing over widest disjoints paths (LBWDP) that are new models for traffic engineering. It also introduces periodic multi-step (PEMS) algorithm that adapts the offered quality depending on the class of the routed traffic.
Źródło:: Journal of Telecommunications and Information Technology; 2009, 1; 5-13
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 14.

Tytuł:: Modeling the Geometry of an Underwater Channel for Acoustic Communication
Autorzy:: Naman, Hala A.
Abdelkareem, A. E.
Powiązania:: https://bibliotekanauki.pl/articles/2174453.pdf
Data publikacji:: 2022
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: channel impulse response
geometry channel model
multipath propagation
underwater acoustic communication
Opis:: The achievement of efficient data transmissions via underwater acoustic channels, while dealing with large data packets and real-time data fed by underwater sensors, requires a high data rate. However, diffraction, refraction, and reflection phenomena, as well as phase and amplitude variations, are common problems experienced in underwater acoustic (UWA) channels. These factors make it difficult to achieve high-speed and long-range underwater acoustic communications. Due to multipath interference caused by surface and ocean floor reflections, the process of modeling acoustic channels under the water’s surface is of key importance. This work proposes a simple geometry-based channel model for underwater communication. The impact that varying numbers of reflections, low water depth values, and distances between the transmitter and the receiver exert on channel impulse response and transmission loss is examined. The high degree of similarity between numerical simulations and actual results demonstrates that the proposed model is suitable for describing shallow underwater acoustic communication environments.
Źródło:: Journal of Telecommunications and Information Technology; 2022, 4; 3--12
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 15.

Tytuł:: Auction Models Supporting End-to-End Connection Trading
Autorzy:: Kołtyś, K.
Pieńkosz, K.
Toczyłowski, E.
Powiązania:: https://bibliotekanauki.pl/articles/309215.pdf
Data publikacji:: 2012
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: bandwidth allocation
divisible commodities
end-to-end connections
multi-commodity trade
multipath routing
Opis:: The paper concerns bandwidth allocation problem on the telecommunication market where there are many sellers and buyers. Sellers offer the bandwidth of telecommunication links. Buyers are interested in the purchase of the bandwidth of several links that makes up an end-to-end connection between two nodes of telecommunication network. We analyze three auction models supporting such a bandwidth exchange: NSP (network second price), BCBT (model for balancing communication bandwidth trading) and BCBT-CG which is a modification of BCBT that applies column generation technique. All of these models concern divisible network resources, treat bandwidth of telecommunication links as an elementary commodity offered for sale, and allow for purchasing bandwidth along multiple paths joining two telecommunication nodes. All of them also aim at maximizing the social welfare. Considered auction models have been compared in the respect of economic and computational efficiency. Experimental studies have been performed on several test instances based on the SNDlib library data sets.
Źródło:: Journal of Telecommunications and Information Technology; 2012, 2; 55-62
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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