126 research outputs found
A low complexity resource allocation algorithm for multicast service delivery in OFDMA networks
Allocating and managing radio resources to multicast transmissions in Orthogonal Frequency-Division Multiple Access (OFDMA) systems is the challenging research issue addressed by this paper. A subgrouping technique, which divides the subscribers into subgroups according to the experienced channel quality, is considered to overcome the throughput limitations of conventional multicast data delivery schemes. A low complexity algorithm, designed to work with different resource allocation strategies, is also proposed to reduce the computational complexity of the subgroup formation problem. Simulation results, carried out by considering the Long Term Evolution (LTE) system based on OFDMA, testify the effectiveness of the proposed solution, which achieves a near-optimal performance with a limited computational load for the system
Multicasting Over 6G Non-Terrestrial Networks: A Softwarization-Based Approach
Multicast/broadcast delivery is a critical challenge of future 6G mobile networks where massive Internet of Things (IoT) deployment and extended reality multimedia such as teleportation are target application scenarios. Non-terrestrial networks (NTNs) are considered essential for the success of 6G, which aims to provide true 'global' services by extending mobile access worldwide, thus overcoming the coverage limit of current terrestrial networks (TNs). This article discusses how the main distinguishing features of NTNs can be effectively exploited for 6G multicasting. Furthermore, in line with the evolution of future 6G networks toward softwarized systems, we evaluate the potential of using the softwarization paradigm in the heterogeneous TN-NTN architecture to deliver multicast services
Multimedia content delivery for emerging satellite networks
Multimedia content delivery over satellite systems is considered as a promising service in the emerging networks. The aim of this work is to design a novel radio resource management (RRM) algorithm for efficiently managing multicast multimedia content transmission over satellite network. The proposed approach performs the spectrum management on a per-group basis, by splitting multicast terminals into different subgroups according to the experienced channel qualities. We demonstrate that subgrouping policy defined by the authors as multicast subgrouping-maximum satisfaction index (MS-MSI), is based on a new metric (i.e., MSI), which overcomes the weakness of the previous techniques proposed in literature and provides the best trade-off between user throughput and fairness. As a further result, we demonstrate that MS-MSI is robust to the long propagation delay of satellite links. An extensive simulation campaign has been conducted by considering several satellite environments
Recommended from our members
Simulation and Performance Analysis of Software-Based Mobile Core Network Architecture (SBMCNA) using OMNeT++
Abstractâ Software defined Networking (SDN) represent the
future framework for the mobile networks. This paper discusses
the required modifications within the EPC in order to overcome
some of the limitations of the current EPS, these modifications
include introducing an SDN based solution Software Based
Mobile Core Network Architecture (SBMCNA), we also show
that Openflow protocol 1.3 has been extended to develop two
methods to support GPRS Tunnelling Protocol (GTP) operations.
The use of an intelligent Forwarding device (FD) were proposed
to reduce the signalling load. SBMCNA were built on OMNeT++
by extending simuLTE [12] and Openflow 1.3 [13] modules. Load
balancing and resiliency were used to demonstrate the capability
of the proposed system to reduce the signalling load. The
preliminary results of the system performance are presented
Boron excess imbalances root/shoot allometry, photosynthetic and chlorophyll fluorescence parameters and sugar metabolism in apple plants
Boron (B) excess frequently impair plant performances and their productivity; in particular in arid and semiâarid environments. In the present experiment; hydroponicallyâgrown âGranny Smithâ apple plants grafted on M9 rootstock were treated with optimal (25 ÎŒÎ) or excess (400 ÎŒÎ) B for 116 days to evaluate allometric responses of plants to B toxicity and to highlight physiological (photosynthesis and chlorophyll fluorescence) and biochemical (pigment content and sugar metabolism) responses of apple plants to B excess. Boron accumulated principally in top > middle > basal stems and leaves of highâBâstressed plants. Notably, the stem dramatically accumulated a higher level of B, as an attempt to preserve leaves, especially the youngest from further B accumulation. B accumulation seriously affected photosynthesis of younger leaves and caused both stomata (reduced stomatal conductance) and biochemical (reduction of apparent CO2 use efficiency and pigment content) limitations and altered the photochemistry and energy partitioning in photosystem II. Boron excess altered leaf sugar proportion; increasing the accumulation of nonâtranslocating sugars such as glucose and fructose. Our dataset adds knowledge on the effect of B excess in apple tree and poses serious concerns about the possible effect of B in altering sugar metabolism; which, in turn, can strongly affect fruit production of this worldwideâcropped species
The assessment and the within-plant variation of the morpho-physiological traits and VOCs profile in endemic and rare Salvia ceratophylloides Ard. (Lamiaceae)
Salvia ceratophylloides (Ard.) is an endemic and rare plant species recently rediscovered as very few individuals at two different Southern Italy sites. The study of within-plant variation is fundamental to understand the plant adaptation to the local conditions, especially in rare species, and consequently to preserve plant biodiversity. Here, we reported the variation of the morpho-ecophysiological and metabolic traits between the sessile and petiolate leaf of S. ceratophylloides plants at two different sites for understanding the adaptation strategies for surviving in these habitats. The S. ceratophylloides individuals exhibited different net photosynthetic rate, maximum quantum yield, light intensity for the saturation of the photosynthetic machinery, stomatal conductance, transpiration rate, leaf area, fractal dimension, and some volatile organic compounds (VOCs) between the different leaf types. This within-plant morpho-physiological and metabolic variation was dependent on the site. These results provide empirical evidence of sharply within-plant variation of the morpho-physiological traits and VOCs profiles in S. ceratophylloides, explaining the adaptation to the local conditions
A novel algorithm for dynamic student profile adaptation based on learning styles
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.E-learning recommendation systems are used to enhance student performance and knowledge by providing tailor- made services based on the studentsâ preferences and learning styles, which are typically stored in student profiles. For such systems to remain effective, the profiles need to be able to adapt and reflect the studentsâ changing behaviour. In this paper, we introduce new algorithms that are designed to track student learning behaviour patterns, capture their learning styles, and maintain dynamic student profiles within a recommendation system (RS). This paper also proposes a new method to extract features that characterise student behaviour to identify studentsâ learning styles with respect to the Felder-Silverman learning style model (FSLSM). In order to test the efficiency of the proposed algorithm, we present a series of experiments that use a dataset of real students to demonstrate how our proposed algorithm can effectively model a dynamic student profile and adapt to different student learning behaviour. The results revealed that the students could effectively increase their learning efficiency and quality for the courses when the learning styles are identified, and proper recommendations are made by using our method
A Centralized Win-Win Cooperative Framework for Wi-Fi and 5G Radio Access Networks
Cooperation to access wireless networks is a key approach towards optimising the use of finite radio spectrum resources in overcrowded unlicensed bands and to help satisfy the expectations of wireless users in terms of high data rates and low latency. Although solutions that advocate this approach have been widely proposed in the literature, they still do not consider a number of aspects that can improve the performance of the usersâ connections, such as the inclusion of: 1) cooperation among network operators, and 2) usersâ quality requirements based on their applications. To fill this gap, in this paper we propose a centralized framework that aims to provide a âwin-winâ cooperation among Wi-Fi and cellular networks, which takes into account 5G technologies and usersâ requirements in terms of Quality of Service (QoS). Moreover, the framework is supported by smart Radio Access Technology (RAT) selection mechanisms that orchestrate the connection of the clients to the networks. In particular, we discuss details on the design of the proposed framework, the motivation behind its implementation, the main novelties, its feasibility and the main components. In order to demonstrate the benefits of our solution, we illustrate efficiency results achieved through the simulation of a smart RAT selection algorithm in a realistic scenario, which mimics the proposed âwin-winâ cooperation between Wi-Fi and cellular 5G networks and we also discuss potential benefits for wireless and mobile network operators
Supplemental red LED light promotes plant productivity, âphotomodulateâ fruit quality and increases Botrytis cinerea tolerance in strawberry
This work provides new evidences on the effect of pre-harvest red (R), green (G), blue (B), and white (W - R:G:B; 1:1:1) LED light supplementation on production, nutraceutical quality and Botrytis cinerea control of harvested strawberry fruit. Yield, fruit color, firmness, soluble solid content, titratable acidity, primary and specialized metabolites, expression of targeted genes and mold development were analyzed in fruit from light-supplemented plants, starting from the strawberry flowering, radiating 250 mu mol m-2 s-1 of light for five hours per day (from 11:00 to 16:00 h), until the fruit harvest. Briefly, R light induced the highest productivity and targeted antho-cyanin accumulation, whilst B and G lights increased the accumulation of primary and secondary metabolites especially belonging to ellagitannin and proanthocyanidin classes. R light also promoted pathogen tolerance in fruit by the upregulation of genes involved in cell wall development (F x aPE41), inhibition of fungus poly-galacturonases (F x aPGIP1) and the degradation of B. cinerea beta-glucans (F x aBG2-1). Our dataset highlights the possibility to use red LED light to increase fruit yield, "photomodulate" strawberry fruit quality and increase B. cinerea tolerance. These results can be useful in terms of future reduction of agrochemical inputs through the use of R light, enhancing, at the same time, fruit production and quality. Finally, further analyses might clarify the effect of pre-harvest supplemental G light on postharvest fruit quality
- âŠ