Search results for "Network"
showing 10 items of 7718 documents
A New Neighbour Selection Strategy for Group-Based Wireless Sensor Networks
2008
In any type of networks a neighbour selection method is needed to form the topology of the network and to know which node the information has to be sent to reach a destination. Nowadays, several selection strategies exist that are based on different aspects and mainly designed to work in common networks. In this paper we will show our study about those different methods and, then we show the development of a suitable neighbour selection strategy for group-based wireless sensor networks (WSN) that is based on a capacity parameter defined by us and the new neighbour distance. We also present the proposal architecture for WSNs and the protocol when a new node joins a group and has to select it…
A survey of wireless data center networks
2015
Data centers are becoming more and more popular for a wide variety of applications. However, the efficiency of data centers are restricted by many issues like cabling and maintenance problems in addition to performance problems like oversubscription. Wireless technology was proposed as it has the capability and the flexibility to offer feasible approaches to solve some of these problems. In this paper, we conduct a deep investigation about wireless data center networks, describe some works that enhance the performance of the network, then give some remarks and critiques. 2015 IEEE. Scopus
Link scheduling in sensor networks for asymmetric average consensus
2012
Wireless Sensor Networks constitute a recent technology where the nodes cooperate to obtain, in a totally distributed way, certain function of the sensed data. One example is the average consensus algorithm, which allows every node to converge to the global average. However, this algorithm presents two major drawbacks in practice. The first one is that instantaneous symmetric links are required, which are hard to ensure in practice because of the presence of wireless interferences. The second one is that all the nodes are required to communicate with all of their local neighbors in every iteration, which can lead to an unbounded delay. In order to solve these issues, we propose a novel link…
Energy efficient and distributed resource allocation for wireless powered OFDMA multi-cell networks
2017
In this paper, we investigate the energy efficient resource allocation problem for the wireless powered OFDMA multi-cell networks. In the considered system, the users who have data to transmit in the uplink can only be empowered by the wireless power obtained from multiple base stations (BSs) with a large scale of multiple antennas in the downlink. A time division protocol is considered to divide the time of wireless power transfer (WPT) in the downlink and wireless information transfer (WIT) in the uplink into separate time slot. With the objective to improve the energy efficiency (EE) of the system, we propose the antenna selection, time allocation, subcarrier and power allocation schemes…
WIDAR: Bistatic WI-fi Detection And Ranging for off-the-shelf devices
2013
The huge spread of wireless networks and the success of location-aware applications require novel indoor po- sitioning mechanisms based on existing technologies such as IEEE 802.11. Taking inspiration from the RADAR, we propose WIDAR: a bistatic WI-fi Detection And Ranging system for off- the-shelf devices. WIDAR implementation is based on the USRP2 platform and is able to locate 802.11 stations while they operate in existing legacy networks. No substitution or repositioning of the Access Points is necessary. WIDAR works passively and does not expect any dedicated action from the target WiFi node. No airtime is wasted and the target cannot even detect that it is being ranged. Such features …
Using self-deferral to achieve fairness between Wi-Fi and NR-U in downlink and uplink scenarios
2022
Wireless networks operating in unlicensed bands generally use one of two channel access paradigms: random access (e.g., Wi-Fi) or scheduled access (e.g., LTE License Assisted Access, LTE LAA and New Radio-Unlicensed, NR-U). The coexistence between these two paradigms is based on listen before talk (LBT), which was, however, designed for random access. Meanwhile, scheduled systems require that their transmissions start at the beginning of a slot boundary. Synchronizing this boundary to the end of LBT usually requires transmitting a reservation signal (RS) to block the channel. Since the RS is a waste of channel resources, we investigate an alternative self-deferral approach (gap-based access…
Achieving Fair Bandwidth Distribution in WiFi Networks: A Game Theoretical Approach
2011
International audience; Achieving fair bandwidth distribution among uplink and downlink ows in IEEE 802.11 infrastructure networks is a complex issue, due to the well-known features of the Distributed Coordination Function (DCF) which regulates the access to the shared medium. Indeed, the dynamic adaptation of the contention windows causes phenomena of short-term unfairness, while the use of homogeneous contention parameters among the contending nodes makes the aggregated downlink bandwidth equal to the uplink bandwidth of a single node. We propose a dynamic tuning of the contention parameters used by the nodes, based on simple network monitoring functionalities and rational strategies. Spe…
Non-conventional yeasts from fermented honey by-products: Focus on Hanseniaspora uvarum strains for craft beer production
2021
The increasing interest in novel beer productions focused on non-Saccharomyces yeasts in order to pursue their potential in generating groundbreaking sensory profiles. Traditional fermented beverages represent an important source of yeast strains which could express interesting features during brewing. A total of 404 yeasts were isolated from fermented honey by-products and identified as Saccharomyces cerevisiae, Wickerhamomyces anomalus, Zygosaccharomyces bailii, Zygosaccharomyces rouxii and Hanseniaspora uvarum. Five H. uvarum strains were screened for their brewing capability. Interestingly, Hanseniaspora uvarum strains showed growth in presence of ethanol and hop and a more rapid growth…
Analysis and modeling of wind directions time series
2013
This work aims at studying some aspects of wind directions in Italy and supplying appropriate models. A comparison is presented between independent mixture and Hidden Markov models, which seem to be appropriate as far as the series we studied.
Wind speed spatial estimation for energy planning in Sicily: introduction and statistical analysis
2008
Abstract The exploitation of the renewable energy sources plays a key role for achieving the CO 2 emissions reduction targets established by the Kyoto Protocol, as well as for facing the shortage of world fossil fuels reserves. In countries like Italy, with an high potential in terms of wind power generation, an efficient energy planning based on renewables is a very complex task. It encompasses many aspects: the resource availability assessment, the compliance with environmental and legislative constraints and last, but not least, the technical aspects linked to the safe integration to the grid of the intermittent power generated by the wind farms. This paper is the first part of a study a…