Search results for "Computer Networks and Communication"
showing 10 items of 834 documents
Enabling a win-win coexistence mechanism for WiFi and LTE in unlicensed bands
2018
The problem of WiFi and LTE coexistence has been significantly debated in the last years, with the emergence of LTE extensions enabling the utilization of unlicensed spectrum for carrier aggregation. Since the two technologies employ com-pletely different access protocols and frame transmission times, supporting coexistence with minimal modifications on existing protocols is not an easy task. Current solutions are often based on LTE unilateral adaptations, being LTE in unlicensed bands still under definition. In this paper, we demonstrate that it is possible to avoid a subordinated role for WiFi nodes, by simply equipping WiFi nodes with a sensing mechanism based on adaptive tunings of the …
Time synchronization enhancements in wireless networks with ultra wide band communications
2022
The emergence of low cost Ultra Wide Band (UWB) transceivers has enabled the implementation of Wireless Sensor Networks (WSN) based on this communication technology. These networks are composed of distributed autonomous low cost nodes (also known as motes) with their own processing unit, memory and communications. Usually these nodes are power-limited and due to the poor performance and quality of their clocks, time synchronization is in the order of milliseconds and in some specific scenarios till microseconds. The integration of commercial UWB transceivers in these nodes can improve the synchronization accuracy. In particular, we focus on WSN nodes based on off-the-shelf commercial produc…
Gatherer: an environmental monitoring application based on IPv6 using wireless sensor networks
2013
In this paper, we present an environmental monitoring application based on IPv6 using wireless sensor networks. We show the guidelines to connect this network to internet using the 6LowPAN standard with a real prototype in the evolution of the Internet of Things. We assign a unique IPv6 address to the different nodes motes of the network. Gatherer is based on TinyOS using IPv6 and UDP protocols and allows the data gathering of temperature and relative humidity from the different motes, requesting specific data from individual motes when required, increasing the accuracy of the measures. We compare the performance of our IPv6-based proposed application against others and show the benefits of…
Benchmarking open data efforts through indices and rankings: Assessing development and contexts of use
2022
Abstract This paper aims to provide a broad perspective on the development of benchmarking open data efforts through indices and rankings over the years, both at the level of countries and allowing for a cross-country comparison. The methodology follows a systematic search for the relevant resources, their classification and identification of six open data benchmarks to be further analyzed, the identification of their key components through decomposition, their description, and identifying the similarities and differences. Three major groups of indices and four periods that characterize the efforts to benchmark and measure the development of open data are identified, where the first measure…
Collaboration and collaborative information technologies
1999
Collaborative information technologies have been claimed to enhance collaboration in organizations, under certain conditions. This claim was found problematic in several respects, also in the light of the results of 18 case studies of Lotus Notes use, taken from the literature. The cases may be split into three groups: (1) exploratory, conservative, or cautious use; (2) planned and expanding use; and (3) extensive and engaged use of Notes. In the first group, no changes in work arrangements due to Notes use could be found. In the second group, the planned Notes applications supported the established work arrangements, both collaborative and hierarchical. Only in the third group were there s…
On the Statistical Properties of Phase Crossings and Random FM Noise in Double Rayleigh Fading Channels
2016
In this paper, we study the statistics of phase processes and random frequency modulation (FM) noise encountered in double Rayleigh fading channels. The Rayleigh processes making up the double Rayleigh channel are assumed to be independent but not necessarily identically distributed. The Doppler power spectral densities of these processes are supposed to be symmetric about the carrier frequency. Under these fading conditions, we derive first an expression for the joint probability density function (jpdf) of the phase process and its rate of change. Capitalizing on this jpdf formula, we then investigate the probability density function (pdf) and cumulative distribution function (cdf) of rand…
Improving RF Fingerprinting Methods by Means of D2D Communication Protocol
2019
Radio Frequency (RF) fingerprinting is widely applied for indoor positioning due to the existing Wi-Fi infrastructure present in most indoor spaces (home, work, leisure, among others) and the widespread usage of smartphones everywhere. It corresponds to a simple idea, the signal signature in a location tends to be stable over the time. Therefore, with the signals received from multiple APs, a unique fingerprint can be created. However, the Wi-Fi signal is affected by many factors which degrade the positioning error range to around a few meters. This paper introduces a collaborative method based on device-to-device (D2D) communication to improve the positioning accuracy using only fingerprin…
Multiple viewpoints increase students' attention to source features in social question and answer forum messages
2016
International audience; Social question & answer forums offer great learning opportunities, but students need to evaluate the credibility of answers to avoid being misled by untrustworthy sources. This critical evaluation may be beyond the capabilities of students from primary and secondary school. We conducted 2 studies to assess how students from primary, secondary, and undergraduate education perceive and use 2 relevant credibility cues in forums: author's identity and evidence used to support his answer. Students didn't use these cues when they evaluated forums with a single answer (Experiment 1), but they recommended more often answers from self‐reported experts than from users with a …
Behavior-based personalization in web search
2016
Personalized search approaches tailor search results to users' current interests, so as to help improve the likelihood of a user finding relevant documents for their query. Previous work on personalized search focuses on using the content of the user's query and of the documents clicked to model the user's preference. In this paper we focus on a different type of signal: We investigate the use of behavioral information for the purpose of search personalization. That is, we consider clicks and dwell time for reranking an initially retrieved list of documents. In particular, we (i) investigate the impact of distributions of users and queries on document reranking; (ii) estimate the relevance …
Assessing the Effect of the Economy for the Common Good System on Business Performance
2023
Extant literature has pointed to organizational hybridity to lever sustainable business transformation. Moreover, some authors hold that there is a possible trade-off between sustainability and performance. However, there is still little empirical evidence on the impact that such sustainability-driven hybridization systems have on performance. Thus, the present study’s main goal is to fill this gap by providing empirical evidence on the impact of the implementation of the Economy for the Common Good, as a sustainability-driven organizational system, on business performance. To do so, the authors relied on a sample of 206 businesses from five European countries. Then, the authors follo…