scholarly journals Long-term evolution of coronal holes on the Sun and occurrence frequencies of magnetic storms with gradual commencements

2021 ◽  
Vol 2103 (1) ◽  
pp. 012038
Author(s):  
S Veretenenko ◽  
M Ogurtsov ◽  
V Obridko ◽  
A Tlatov
Keyword(s):  
Coronal Holes ◽  
Long Term Evolution ◽  
Magnetic Storms ◽  
Time Shift ◽  
Time Interval ◽  
The Sun ◽  
Close Link ◽  
Sunspot Numbers ◽  
Term Evolution

Abstract Long-term evolution of areas with open configuration of magnetic field (coronal holes) on the Sun reconstructed on the basis of H-alpha synoptic charts for the period 1887-2016 was studied and compared with annual occurrence frequencies of magnetic storms with gradual (GC) commencements. It was found that correlation between yearly values of coronal hole (CH) areas and sunspot numbers with no time shift is negative and not strong, but increases up to ∼0.6-0.7 when CH areas are delayed by 4-5 years relative to sunspot numbers. Temporal variations of CH areas in the Northern and Southern hemispheres are characterized by dominant ∼11-year periodicities; however, they differ significantly on the multidecadal time scale. The wavelet spectra of CH areas in the Southern hemisphere, unlike those in the Northern one, reveal persistent periodicities of ∼30-35 years on the studied time interval. Similar periodicities of ∼30-35 years are observed in annual occurrences of GC magnetic storms which are caused by high-speed streams of solar wind from coronal holes. The results of cross wavelet analysis of annual occurrence frequencies of GC magnetic storms and areas of coronal holes revealed common periodicities ∼11, ∼35 and ∼60 years which confirmed a close link of these storms with the evolution of large-scale magnetic fields on the Sun.

scholarly journals New Courteous Algorithm for Uplink Scheduling in LTE-Advanced and 5G Networks

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Chafika Tata ◽  
Nassima Fellag ◽  
Michel Kadoch
Keyword(s):  
Long Term Evolution ◽  
Time Interval ◽  
5G Networks ◽  
Lte Networks ◽  
Uplink Scheduling ◽  
Term Evolution ◽  
Radio Access ◽  
Management Scheme ◽  
Wireless Users

The fast evolution of the number of wireless users and the emergence of new multimedia services have motivated third-generation partnership project (3GPP) to develop new radio access technologies. Thus, the carrier aggregation (CA) was introduced from version 10 long-term evolution (LTE), known as long-term evolution-advanced (LTE-A), to meet the increasing demands in terms of throughput and bandwidth and to ensure the Quality of Service (QoS) for different classes of bearers in LTE networks. However, such solution stills inefficient until implementing good resources management scheme. Several scheduling mechanisms have been proposed in the literature, to guarantee the QoS of different classes of bearers in LTE-A and 5G networks. Nevertheless, most of them promote high-priority bearers. In this study, a new approach of uplink scheduling resources has been developed. It aims to ensure service fairness of different traffic classes that allocates bearers over LTE-A and 5G networks. Also, it raises the number of admitted users in the network by increasing the number of admitted bearers through a dynamic management of service priorities. In fact, the low-priority traffic classes, using low-priority bearers, are favoured during a specific time interval, based on the average waiting time for each class. Simulation results show that the QoS parameters were much improved for the low-priority classes without significantly affecting the QoS of high priority ones.

Link-Level Simulator for Wireless local Area Network

2018 ◽  
Vol 6 (7) ◽  
pp. 314
Author(s):  
Chaithra. H. U ◽  
Vani H.R
Keyword(s):  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area Networks ◽  
Local Area ◽  
Long Term Evolution ◽  
Wireless Local Area Networks ◽  
Area Network ◽  
Network Simulator ◽  
Term Evolution

Now a days in Wireless Local Area Networks (WLANs) used in different fields because its well-suited simulator and higher flexibility. The concept of WLAN  with  advanced 5th Generation technologies, related to a Internet-of-Thing (IOT). In this project, representing the Network Simulator (NS-2) used linked-level simulators for Wireless Local Area Networks and still utilized IEEE 802.11g/n/ac with advanced IEEE 802.11ah/af technology. Realization of the whole Wireless Local Area Networking linked-level simulators inspired by the recognized Vienna Long Term Evolution- simulators. As a outcome, this is achieved to link together that simulator to detailed performances of Wireless Local Area Networking with Long Term Evolution, operated in the similar RF bands. From the advanced 5th Generation support cellular networking, such explore is main because different coexistences scenario can arise linking wireless communicating system to the ISM and UHF bands.

Simulación de cobertura del modelo de radio propagación 3GPP para un entorno urbano en una red 4G – LTE

2013 ◽  
Vol 8 (15) ◽  
pp. 33-40
Author(s):  
Javier Enrique Arévalo Peña
Keyword(s):  
Long Term Evolution ◽  
Term Evolution ◽  
Nuevas Tecnologías ◽  
4G Lte ◽  
3Rd Generation Partnership Project

En la planeación de las próximas generaciones de redes inalámbricas es importante contar con estudios de radio propagación que permitan establecer diseños adecuados para ofrecer los servicios proyectados por las nuevas tecnologías a los usuarios móviles. En este artículo se presentan aspectos relacionados con el comportamiento de cobertura de radio propagación del modelo propuesto por el 3GPP (3rd Generation Partnership Project) para un entorno urbano en una red LTE (Long Term Evolution) empleando sistemas de antenas convencionales y sistemas de antena adaptativas (AAS). Para ello se utiliza la herramienta de software ICS Designer y se establece como escenario los alrededores la Fundación Universidad Autónoma de Colombia ubicada en el centro urbano de la ciudad de Bogotá D. C.

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