New Radio-based access to Unlicensed spectrum (NR-U) intends to expand the applicability of 5G NR access technology to support operation in unlicensed bands by adhering to Listen-Before-Talk (LBT) ...requirement for accessing the channel. As the NR-U specification is being developed, simulations to assess the performance of NR-U and IEEE 802.11 technologies coexistence in unlicensed spectrum bands are crucial. In this paper, we report on extensions to a popular and open source network simulator, ns-3, to build an NR-U system-level simulator and to model the NR-U and IEEE 802.11 technologies coexistence in the currently available unlicensed spectrum bands. The proposed NR-U model capitalizes on an NR Release-15 based model that has been extended to operate in unlicensed bands, while meeting its regulatory requirements. For the coexistence analysis, we pay particular attention to the millimeter-wave bands and provide a complete set of simulation campaigns evaluating the coexistence of NR-U and IEEE 802.11ad Wireless Gigabit (WiGig) in the 60 GHz bands. In particular, we focus on determining whether NR-U fulfills its coexistence objective in terms of a fairness criterion by testing different NR-U parameters, such as the numerology, the bandwidth, the channel access scheme, the energy detection threshold, and the beamforming method.
5G networks are designed to support a variety of services with highly demanding Quality-of-Service (QoS) requirements. This opened the door for novel extended reality (XR) media applications to ...emerge with 5G. However, recent 5G field tests and system-level simulation studies show that further XR enhancements are required to support a massive adoption of XR services in 5G networks. Such enhancements are expected to come into play with 5G-Advanced. In this line, we propose and study an XR loopback mechanism that adapts the XR traffic to the instantaneous 5G network conditions by exploiting an XR application feedback. We propose various XR loopback algorithms, strategies, and parameters' configurations and study their impact on the 5G end-to-end performance. We conduct extensive simulation campaigns by building realistic end-to-end 5G network scenarios with 3GPP mixed XR traffic setups. Results show that the proposed XR loopback mechanism can boost XR performance in 5G networks by adapting to 5G network conditions, while keeping the XR QoS requirements under control. We provide various insights and practical directions on XR loopback design that allow us to take full advantage of the 5G network capabilities and progress toward 5G-Advanced network design.
Recently, there has been much interest by the cellular network industry in utilizing unlicensed spectrum to expand potential capacity. In particular, two LTE unlicensed technologies gained much ...attention: licensed-assisted access (LAA) and LTE unlicensed (LTE-U). While these are rapidly entering the market, there are not many studies in the literature that are providing a complete evaluation and comparison of their performance. Available work usually focuses on single technology standalone evaluations. Also, despite the vast body of simulation results by industry and academia, the simulators are not publicly available, and the analytical models proposed in the literature do not offer complex enough frameworks for thorough performance evaluations. To carry out an evaluation study, we have built a comprehensive simulation platform, strictly complying with the standards and specifications of each technology. The models are built upon popular ns-3 simulator, have been designed in close consultation with industry experts, and have been validated through calibration processes and against analytical proposals and experimental platforms. In this paper, we provide a detailed overview, performance evaluation, and comparison of LAA and LTE-U in a wide variety of scenarios, following 3GPP and Wi-Fi Alliance (WFA) guidelines. We show that despite the market is confirming LAA as the leading unlicensed LTE technology, in certain setups, efficient implementations of LTE-U may prove unexpectedly better in coexisting with Wi-Fi. Similarly, the expected behaviors of the LAA LBT procedure can reveal untrue, depending on the traffic or interference patterns and specific implementation details, even in Wi-Fi. This paper also includes scenarios involving TCP, which is a rarely treated topic in the literature in the context of LTE and Wi-Fi coexistence. The end-to-end and full protocol stack simulation platform is openly available to foster results' reproducibility and collaborative development.
The full potential of the Internet of Musical Things (IoMusT) paradigm can be fully unleashed only in the presence of widespread, reliable wireless connectivity, allowing musicians to connect their ...smart instruments (almost) anywhere they are. For this reason, we propose a realistic, end-to-end communication architecture for a IoMusT system based on public fifth-generation (5G) mobile networks that considers a networked music performance use case, and we introduce a model for the resulting system. We define high-level service requirements and key performance indicators for the network's connect-compute architecture. We evaluate our solution via system-level simulations using the well-known 5G-LENA/ns3 and Simu5G/OMNeT++ frameworks. We found that operating 6 or more IoMusT devices over a fourth-generation (4G) network results in a worst-case latency well over 20 ms for more than 90% of the packet transmissions, while losing more than 10% of packets. On the other hand, operating the same number of devices over a 5G network reduces the latency significantly. After testing our findings both in single-cell and in multi-cell scenarios, assuming a transient in the upgrade of mobile network infrastructures from 4G to 5G, we consider a E-UTRA-NR dual connectivity (EN-DC) scenario, where a 5G base station serves a subset of the users of a 4G cell. Furthermore, we conducted a user study where musicians were asked to assess their playing experience during simulated 4G- and 5G-based networked music performances. The results of the simulations and of the user study consistently indicate that the use of 5G technology improves performance significantly, and advocate the need for a 5G framework to fully support the IoMusT.
An E2E simulator for 5G NR networks Patriciello, Natale; Lagen, Sandra; Bojovic, Biljana ...
Simulation modelling practice and theory,
November 2019, 2019-11-00, Volume:
96
Journal Article
Peer reviewed
Open access
As the specification of the new 5G NR standard proceeds inside 3GPP, the availability of a versatile, full-stack, End-To-End (E2E), and open source simulator becomes a necessity to extract insights ...from the recently approved 3GPP specifications. This paper presents an extension to ns-3, a well-known discrete-event network simulator, to support the NR Radio Access Network. The present work describes the design and implementation choices at the MAC and PHY layers, and it discusses a technical solution for managing different bandwidth parts. Finally, we present calibration results, according to 3GPP procedures, and we show how to get E2E performance indicators in a realistic deployment scenario, with special emphasis on the E2E latency.
This paper elaborates on the design challenges, opportunities, and solutions for New Radio-based access to Unlicensed spectrum (NR-U) by taking into account the beam-based transmissions and the ...worldwide regulatory requirements. NR-U intends to expand the applicability of 5th generation New Radio access technology to support operation in unlicensed bands by adhering to Listen-Before-Talk (LBT) requirements for accessing the channel. LBT was already adopted by different variants of 4th generation Long Term Evolution (LTE) in unlicensed spectrum, i.e., Licensed-Assisted Access and MulteFire, to guarantee fair coexistence among different radio access technologies. In the case of beam-based transmissions, the NR-U coexistence framework is significantly different as compared to LTE in unlicensed spectrum due to the use of directional antennas, which enhance the spatial reuse but also complicate the interference management. In particular, beam-based transmissions are needed in the unlicensed spectrum at millimeter-wave (mmWave) bands, which is an attractive candidate for NR-U due to its large amount of allocated spectrum. As a consequence, some major design principles need to be revisited to address coexistence for beam-based NR-U. In this paper, different problems and the potential solutions related to channel access procedures, frame structure, initial access procedures, re-transmission procedures, and scheduling schemes are discussed. A simulation evaluation of different LBT-based channel access procedures for NR-U/Wi-Fi indoor mmWave coexistence scenarios is also provided.
Due to the rapid technology evolution and standardization activity in the mobile communication networks, there is the need for the research community to be able to develop, test and evaluate new ...and/or already existing solutions before industrial or real-network implementation. As such, it is essential to have an open-source tool that provides an alternative solution to that of industrial proprietary simulators that are not available for public usage. ns-3 5G-LENA simulator is an end-to-end open-source NR system-level simulator that allows extensive research to be performed. However, it is of great importance to guarantee that the results obtained using the simulator can be comparable to that of industrial simulators and real networks. For this reason, calibrating the simulator based on 3GPP defined specifications is crucial. Based on the above, in this paper we calibrate the ns-3 5G-LENA simulator according to the 3GPP reference results for NR-based outdoor deployments. Moreover, we explore the REM feature provided by the simulator, to ease the calibration process and understand better the radio environment. Results show the resemblance of the simulator performance to that of simulators used as references by 3GPP.
Abstract The genus Stachys includes about 300 cosmopolitan species, making it one of the largest genera of the Lamiaceae family. The purpose of this paper is to present a review of Stachys species in ...the flora of Serbia among which some species are endemic to the Balkan Peninsula. This review comprises morphological, phytochemical, medicinal and food application of 17 taxa: S. аlopecuros, S. аlpina, S. аnisochila, S. аnnua, S. аtherocalyx, S. cretica subsp. cassia, S. germanica, S. leucoglossa, S. milanii, S. officinalis, S. palustris, S. plumose, S. recta, S. tymphaea, S. scardica, S. serbica, and S. sylvatica. The species of the genus Stachys are rich sources of biologically active substances and well known for their worldwide application. For most of the Stachys species, it has been shown that their extracts possess biological activities such as antibacterial, anti-inflammatory, antioxidant, and anticancer. The main goals of this review include the morphological description of species, representation of the major secondary metabolites, and presentation of traditional knowledge in food preparation.
Abstract The family Amaranthaceae contains a large number of halophytic species. The aim of this paper is to present a review of biologically significant halophytes in the flora of Serbia belonging ...to this family. This review includes a description of the following 18 species: Atriplex littoralis L., A. rosea L., A. halimus L., Bassia sedoides Pall., B. scoparia (L.) A.J.Scott., B. prostrata (L.) Beck., Beta trigyna W. et K., Camphorosma annua Pall., C. monspeliaca L., Chenopodium ambrosioides L., Ch. polyspermum L., Ch. vulvaria L., Ch. hybridum L., Ch. album L., Ch. rubrum L., Salicornia europaea L., Suaeda maritima (L.) Dum., Salsola soda L. These species are sources of biologically active substances and have a good potential for multi-purpose applications. Most extracts of these species have been found to exhibit biological activities such as antioxidant, anticancer, antibacterial, antifungal, antiinflammatory and others. The aim of this review is to describe these species including their morphology, distribution, phytochemistry, as well as their use for medicinal and food purposes.
Chilling stress in spring and mid-season heat stress are important environmental stresses that can significantly affect plant productivity. The objectives of this study were to understand the effects ...of cold (4 and 10 °C) or heat (30 and 40 °C) stress on biochemical and physiological traits in leaves and roots of basil (
L. cv. 'Genovese') young plants. After short-time exposure to mild and severe temperature stresses, both photosynthetic pigments' and protein, as well as enzymatic and non-enzymatic defense components in basil leaves and roots, were quantified and compared with the control non-stressed plants. It was shown that both cold and heat treatment increase the content of chlorophyll
, chlorophyll
, and carotenoids. Chilling correlated with higher content of soluble proteins in leaves, whereas the concentration of these osmoprotectants in roots was higher under both cold and heat stress. For all tested antioxidant enzymes, higher activity was measured in leaves, and activity was related to temperature stress. SOD, CAT, A-POX, and P-POX activities was induced under heat stress, while the higher activity of SOD, CAT, P-POX, and G-POX was recorded under cold stress, compared to the control. In addition to the induced activity of enzymatic components, the content of secondary metabolites including total phenolics, flavonoids, and total anthocyanins, was several times higher compared to the non-stressed plants. Furthermore, total phenolic content was higher in roots than in leaves. Significant positive correlation can be seen among photosynthetic pigments, SOD, total phenolics, and flavonoids under severe temperature stress (4 or 40 °C) in basil leaves, while for roots, positive correlation was found in the content of secondary metabolites and activity of CAT or peroxidases. Obtained results are discussed in terms of phenotyping of
cv. 'Genovese' response to heat and chilling stress, which should contribute to a better understanding of merged responses to cold and heat tolerance of this valuable crop.
PDF
