Search results for "gateway"

Imagining Europe's Borders : Commemorative Art of Migrant Tragedies

2016

Measurement and Modeling of the Origins of Starvation in Congestion Controlled Mesh Networks

2008

Significant progress has been made in understanding the behavior of TCP and congestion-controlled traffic over multi- hop wireless networks. Despite these advances, however, no prior work identified severe throughput imbalances in the basic scenario of mesh networks, in which one-hop flows contend with two-hop flows for gateway access. In this paper, we demonstrate via real network measurements, test-bed experiments, and an analytical model that starvation exists in such a scenario, i.e., the one-hop flow receives most of the bandwidth while the two- hop flow starves. Our analytical model yields a solution consisting of a simple contention window policy that can be implemented via mechanism…

An experimental testbed of an Internet of Underwater Things

2020

A number of critical features have so far slowed down the realization of an Internet of Underwater Things. The most relevant of these aspects are related to the unreliability of the communication channel, the long propagation delay and the effect of severe multi-path and fading. This paper presents the design and development of a hybrid underwater-terrestrial IoT where different underwater sensors collect heterogeneous data and use marine acoustic modems to send information to a gateway device; this is able to set up a long distance link, implemented through a LoRaWAN connection, to forward data to a remote cloud for further processing. Performance of this system has been tested in a real s…

Palermo Blue/Green Gateway. Nove porte per la knowledge city

2015

Il saggio esplora le trasformazioni della linea di costa dell'area metropolitana di Palermo e traccia linee ed indirizzi di trasformazione legate alla rigenerazione di nove porti intesi come nuove porte di accesso alla città stessa. Il saggio presenta l'ipotesi di trasformazione e rigenerazione urbana ed architettonica che l'autore ha elaborato in occasione della candidatura di Palermo a Capitale Europea della Cultura per il 2019, in qualità di membro della cabina di regia e del coordinamento scientifico della candidatura. Lo scritto porta avanti una ipotesi teorica e di ricerca fondata sulla postproduzione urbana e architettonica e sulla knowledge city come tema trainante per la rigenerazi…

ECAR: an Energy/Channel Aware Routing Protocol For Cooperative Wireless Sensor Networks

2011

International audience; The proliferation of low power networks like Wireless Sensor Networks (WSN) rose up new challenges. Power conservation and channel quality become the most important parameters. Obviously, hop count based routing protocols are no more adapted to such networks having power limitations and channel problems. Several alternatives were suggested to cope with these constraints. In MAC layer for example, cooperative protocols were designed to enhance the channel use: the neighbor nodes help the source to retransmit its packets. However, if the path proposed by the routing protocol contains poor channels, the cooperative communications will not save all the packets. Therefore…

NICE-MRP: a Near-Optimal Radio-Interference Aware Multi-path Routing Protocol for MANETs

2013

International audience; Nowadays, with the miniaturization of communication devices, dense and highly mobile ad-hoc networks are very common. Besides, more and more devices have several radio interfaces. In such an environment, multi-path routing should be considered. Yet, only few multi-path ad-hoc routing protocols take into account the radio-interferences which might arise between two geographically close routes. Moreover, they generally only forbid the addition of interfering paths rather than looking for a different, more optimized, solution. This paper presents NICE-MRP, a novel multi-path routing protocol for mobile ad-hoc networks giving efficient solutions with respect to physical …

Distributed routing and channel allocation in multi-channel multi-hop ad hoc networks

2013

In this paper, we propose a novel routing protocol which is integrated with channel assignment for multi-channel multi-hop wireless ad hoc networks. In such a network, each node is equipped with three transceivers. One is always tuned on a control channel which is responsible for control and broadcast messages, and the other two perform as transmitter and receiver respectively for traffic flows on different data channels. The routing protocol works in an on-demand manner, and the proposed routing discovery process selects a path that potentially traverses nodes with lighter traffic load and lower number of carried flows. With a given number of non-overlapping channels, the optimal solution …

A combined relay-selection and routing protocol for cooperative wireless sensor networks

2012

International audience; In wireless sensor networks several constraints decrease communications performances. In fact, channel randomness and energy restrictions make classical routing protocols inefficient. Therefore, the design of new routing protocols that cope with these constraints become mandatory. The main objective of this paper is to present a multi-objective routing algorithm RBCR that computes routing path based on the energy consumption and channel qualities. Additionally, the channel qualities are evaluated based on the presence of relay nodes. Compared to AODV and AODV associated to a cooperative MAC protocol, RBCR provides better performances in term of delivery ratio, power …

Distance Constrained Mapping to Support NoC Platforms Based on Source Routing

2010

Efficient NoC is crucial for communication among processing elements in a highly parallel processing systems on chip. Mapping cores to slots in a NoC platform and designing efficient routing algorithms are two key problems in NoC design. Source routing offers major advantages over distributed routing especially for regular topology NoC platforms. But it suffers from a serious drawback of overhead since it requires whole communication path to be stored in every packet header. In this paper, we present a core mapping technique which helps to achieve a mapping with the constraint over the path length. We have found that the path length constraint of just 50% is sufficient in most cases. We als…

A Network Protocol to Enhance Robustness in Tree-Based WSNs Using Data Aggregation

2007

This paper proposes a data gathering strategy for wireless sensor networks and an implementation based on the IEEE 802.15.4 standard. The algorithm combines the benefits of single-path and multi-path routing strategies in a hybrid solution which makes use of alternative paths when necessary. We adopt a caching and retransmission technique, which exploits some peculiar features of data aggregation, with the use of implicit acknowledgments of reception. The paper also discusses simulation results that show how the mentioned techniques, combined with exploitation of the features of the IEEE 802.15.4 standard have been used to obtain an efficient protocol that takes energy consumption into acco…