Search results for "Organization"
showing 10 items of 4550 documents
A random-walk benchmark for single-electron circuits
2021
Mesoscopic integrated circuits aim for precise control over elementary quantum systems. However, as fidelities improve, the increasingly rare errors and component crosstalk pose a challenge for validating error models and quantifying accuracy of circuit performance. Here we propose and implement a circuit-level benchmark that models fidelity as a random walk of an error syndrome, detected by an accumulating probe. Additionally, contributions of correlated noise, induced environmentally or by memory, are revealed as limits of achievable fidelity by statistical consistency analysis of the full distribution of error counts. Applying this methodology to a high-fidelity implementation of on-dema…
Live demonstration: multiplexing AER asynchronous channels over LVDS Links with Flow-Control and Clock-Correction for Scalable Neuromorphic Systems
2017
Paper presented at the 2017 IEEE International Symposium on Circuits and Systems (ISCAS), held in Baltimore, MD, USA, on 28-31 May 2017.
Effect of Footstep Vibrations and Proprioceptive Vibrations Used with an Innovative Navigation Method
2017
This study proposes to investigate the effect of adding vibration feedback to a navigation task in virtual environment. Previous study used footstep vibrations and proprioceptive vibrations in order to decrease the cyber-sickness and increase the sense of presence. In this study, we experiment the same vibration modalities but with a new navigation method. The results show that proprioceptive vibrations do not impact the sense of presence neither the cyber-sickness while footstep vibrations increase sense of presence and decrease in a certain way cyber-sickness. Burgundy region through the JCE funding project
The role of the Access Point in Wi-Fi networks with selfish nodes
2009
In Wi-Fi networks, mobile nodes compete for accessing the shared channel by means of a random access protocol called Distributed Coordination Function (DCF), which is long term fair. But recent drivers allow users to configure protocol parameters differently from their standard values in order to break the protocol fairness and obtain a larger share of the available bandwidth at the expense of other users. This motivates a game theoretical analysis of DCF. Previous studies have already modeled access to a shared wireless channel in terms of non-cooperative games among the nodes, but they have mainly considered ad hoc mode operation. In this paper we consider the role of the Access Point (AP…
An adaptive cooperative MAC mechanism in multi-hop wireless networks
2010
In this paper, we propose a novel adaptive cooperative MAC mechanism that is specifically designed for two-hop cooperative communications where source and destination cannot hear each other directly. The proposed scheme employs an efficient adaptive relay selection algorithm such that the number of relay nodes is optimized for each cooperative transmission to maximize cooperation benefits and effectively avoid potential collisions with other transmissions. In order to determine the optimal number of relays we apply a training sequence in Hello message exchange, which provides us with a channel status indicator combining both bit-level and flow-level information. Numerical results show that …
A contention-based multiple access protocol in cooperative wireless networks
2010
Cooperative communication has emerged as a promising technique to enhance system performance in wireless networks. This paper proposes a contention-based cooperative multiple medium access control protocol by means of multiple retransmissions of the same packet from different relay nodes. The proposed scheme exploits cooperative communication capability not only from time diversity derived from multiple temporal transmissions but also spatial diversity derived from distributed multiple relays. A Markov chain is introduced to analyze the throughput performance of the proposed cooperative scheme. The performance evaluation of the protocol is validated and compared with non-cooperative ARQ pro…
Testbed evaluation of optimized REACT over multi-hop paths
2018
REACT is a distributed resource allocation protocol that computes a max-min allocation of airtime for mesh networks. The allocation adapts automatically to changes in local traffic load and in local network views. SALT, a new contention window tuning algorithm, ensures that each node secures the airtime allocated to it by REACT. REACT and SALT are extended to the multi-hop flow scenario with the introduction of a new airtime reservation algorithm. With a reservation in place, multi-hop TCP flows show increased throughput when running over SALT and REACT compared to running over 802.11 DCF. All results are obtained from experimentation on the w-iLab.t wireless network testbed in Belgium.
ErrorSense: Characterizing WiFi Error Patterns for Detecting ZigBee Interference
2014
Recent years have witnessed the increasing adoption of heterogeneous wireless networks working in unlicensed ISM bands, thus creating serious problems of spectrum overcrowding. Although ZigBee, Bluetooth and WiFi networks have been natively designed for working in presence of interference, it has been observed that several performance impairments may occur because of heterogeneous sensitivity to detect or react to the presence of other technologies. In this paper we focus on the WiFi capability to detect interfering ZigBee links. Despite of the narrowband transmissions performed by ZigBee, in emerging scenarios ZigBee interference can have a significant impact on WiFi performance. Therefore…
MAC Protocols for Wake-up Radio: Principles, Modeling and Performance Analysis
2018
[EN] In wake-up radio (WuR) enabled wireless sensor networks (WSNs), a node triggers a data communication at any time instant by sending a wake-up call (WuC) in an on-demand manner. Such wake-up operations eliminate idle listening and overhearing burden for energy consumption in duty-cycled WSNs. Although WuR exhibits its superiority for light traffic, it is inefficient to handle high traffic load in a network. This paper makes an effort towards improving the performance of WuR under diverse load conditions with a twofold contribution. We first propose three protocols that support variable traffic loads by enabling respectively clear channel assessment (CCA), backoff plus CCA, and adaptive …
From fractal urban pattern analysis to fractal urban planning concepts
2014
International audience; Fractal geometry can be used to develop a multiscale approach toinvestigate the spatial organization of urban fabrics. First, the concepts behindfractal reference models are introduced so as to provide a better understandingof the results obtained from empirical analyses of urban patterns. Then, differentmethods for conducting fractal analyses are presented and the results obtained forurban patterns are discussed. It turns out that, despite their irregular appearance,urban patterns are often organized by an inherent fractal order principle, at leastacross a certain range of scales. More detailed analysis of the findings reveals linksbetween these fractal properties a…