Search results for "Computer network"

Dynamic Flow-Adaptive Spectrum Leasing with Channel Aggregation in Cognitive Radio Networks.

2020

Cognitive radio networks (CRNs), which allow secondary users (SUs) to dynamically access a network without affecting the primary users (PUs), have been widely regarded as an effective approach to mitigate the shortage of spectrum resources and the inefficiency of spectrum utilization. However, the SUs suffer from frequent spectrum handoffs and transmission limitations. In this paper, considering the quality of service (QoS) requirements of PUs and SUs, we propose a novel dynamic flow-adaptive spectrum leasing with channel aggregation. Specifically, we design an adaptive leasing algorithm, which adaptively adjusts the portion of leased channels based on the number of ongoing and buffered PU …

Efficient Hybrid Emergency Aware MAC Protocol for Wireless Body Sensor Networks

2018

International audience; In Body Sensor Networks (BSNs), two types of events should be addressed: periodic and emergency events. Traffic rate is usually low during periodic observation, and becomes very high upon emergency. One of the main and challenging requirements of BSNs is to design Medium Access Control (MAC) protocols that guarantee immediate and reliable transmission of data in emergency situations, while maintaining high energy efficiency in non-emergency conditions. In this paper, we propose a new emergency aware hybrid DTDMA/DS-CDMA protocol that can accommodate BSN traffic variations by addressing emergency and periodic traffic requirements. It takes advantage of the high delay …

Managing sensor data streams in a smart home application

2020

A challenge in developing an ambient activity recognition system for use in elder care is finding a balance between the sophistication of the system and a cost structure that fits within the budgets of public and private sector healthcare organisations. Much activity recognition research in the context of elder care is based on dense networks of sensors and advanced methods, such as supervised machine learning algorithms. This paper presents the data processing aspects of an activity recognition system based on a simpler, knowledge-based unsupervised approach, designed for a sparse network of sensors. By structuring sensor data management as a streaming system, we provide a simple programmi…

Revenue models, in-app purchase, and the app performance: Evidence from Apple's App Store and Google Play

2016

The effect of revenue models on app performance depends on the app store.The effect of in-app purchase on app performance depends on the app store.Paid, freemium and in-purchase models are shown to be effective in app store.Freemium and in-app purchase models are shown to be less effective in Google Play.App category influences the effects of both revenue models and in-app purchase. In this paper, we empirically examine how the revenue model (paid, free, or freemium) adopted for a given app affects the app revenue performance as measured by the app daily revenue rank. We also study the impact of in-app purchase on this measure of performance. Moreover, we study how such relationships are co…

More than experience? On the unique opportunities of virtual reality to afford a holistic experiential learning cycle

2021

Virtual reality has been proposed as a promising technology for higher education since the combination of immersive and interactive features enables experiential learning. However, previous studies did not distinguish between the different learning modes of the four-stage experiential learning cycle (i.e., concrete experience, reflective observation, abstract conceptualization, and active experimentation). With our study, we contribute a deeper understanding of how the unique opportunities of virtual reality can afford each of the four experiential learning modes. We conducted three design thinking workshops with interdisciplinary teams of students and lecturers. These workshops resulted in…

An Efficient Immunization Strategy Using Overlapping Nodes and Its Neighborhoods

2018

International audience; When an epidemic occurs, it is often impossible to vaccinate the entire population due to limited amount of resources. Therefore, it is of prime interest to identify the set of influential spreaders to immunize, in order to minimize both the cost of vaccine resource and the disease spreading. While various strategies based on the network topology have been introduced, few works consider the influence of the community structure in the epidemic spreading process. Nowadays, it is clear that many real-world networks exhibit an overlapping community structure, in which nodes are allowed to belong to more than one community. Previous work shows that the numbers of communit…

Argumentation graphs with constraint-based reasoning for collaborative expertise

2018

International audience; Collaborative processes are very important in telemedicine domain since they allow for making right decisions in complex situations with multidisciplinary staff. When modelling these collaborative processes, some inconsistencies can appear. In semantic modelling (conceptual graphs), these inconsistencies are verified using constraints. In this work, collaborative processes are represented using an argumentation system modelled in a conceptual graph formalism where inconsistencies could be particular bad attack relation between arguments. To overcome these inconsistencies, two solutions are proposed. The first one is to weight the arguments evolving in the argumentati…

Perceived-Value-driven Optimization of Energy Consumption in Smart Homes

2020

Residential energy consumption has been rising rapidly during the last few decades. Several research efforts have been made to reduce residential energy consumption, including demand response and smart residential environments. However, recent research has shown that these approaches may actually cause an increase in the overall consumption, due to the complex psychological processes that occur when human users interact with these energy management systems. In this article, using an interdisciplinary approach, we introduce a perceived-value driven framework for energy management in smart residential environments that considers how users perceive values of different appliances and how the us…

Mobile Computing Environment

2002

The Brave New World of development in the internetwork computing architecture (InterNCA): or how distributed computing platforms will change systems …

1998

This essay is a speculation of the impact of the next generation technological platform — the internetwork computing architecture (InterNCA) — on systems development. The impact will be deep and pervasive and more substantial than when computing migrated from closed computer rooms to ubiquitous personal computers and flexible client-server solutions. Initially, by drawing upon the notion of a technological frame, the InterNCA, and how it differs from earlier technological frames, is examined. Thereafter, a number of hypotheses are postulated with regard to how the architecture will affect systems development content, scope, organization and processes. Finally, some suggestions for where the…