Search results for " Communication"

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…

Assessment of sensitization to grape and wine allergens as possible causes of adverse reactions to wine: a pilot study.

2015

Background In a recently performed survey with 4000 randomly selected persons, 68 (7.2 %) of 948 respondents reported intolerance and/or allergy-like symptoms to wine. The aim of this study was to analyze whether a real sensitization to wine proteins could be confirmed by diagnostic and/or immunological settings. Findings For this purpose, 19 subjects with self-reported intolerance to wine of the invited subjects and 10 controls without a history of intolerance participated in an allergological examination (skin prick test, ImmunoCAP for determination of specific IgE antibodies, CAST for testing basophil activation, ImmunoBlot for testing specificity of IgE-antibodies). For the allergologic…

Message from BWCCA 2012 international conference workshop co-chairs

2012

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

2009

Significant progress has been made in understanding the behavior of TCP and congestion-controlled traffic over CSMA-based multihop wireless networks. Despite these advances, however, no prior work identified severe throughput imbalances in the basic scenario of mesh networks, in which a one-hop flow contends with a two-hop flow for gateway access. In this paper, we demonstrate via real network measurements, testbed 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 vi…

Experimental characterization and mitigation of turbulence induced signal fades within an ad hoc FSO network

2014

Optical beams propagating through the turbulent atmospheric channel suffer from both the attenuation and phase distortion. Since future wireless networks are envisaged to be deployed in the ad hoc mesh topology, this paper presents the experimental laboratory characterization of mitigation of turbulence induced signal fades for two ad hoc scenarios. Results from measurements of the thermal structure constant along the propagation channels, changes of the coherence lengths for different turbulence regimes and the eye diagrams for partially correlated turbulences in free space optical channels are discussed. Based on these results future deployment of optical ad hoc networks can be more strai…

Making WiFi work in multi-hop topologies: Automatic negotiation and allocation of airtime

2015

We propose a solution for mitigating the performance impairments of CSMA/CA protocols in multi-hop topologies based on the dynamic adaptation of the contention process experienced by nodes in a wireless network. A distributed protocol is used to negotiate the channel airtime for a node as a function of the traffic requirements of its neighbourhood, taking into account bandwidth reserved for the control operations. A mechanism is provided for a node to tune its contention window depending on its allocated airtime. Different from previous schemes, a node's contention window is fixed in size unless the traffic requirements of its neighbourhood change. The scheme is implemented on legacy commer…

Disentangling canid howls across multiple species and subspecies: Structure in a complex communication channel

2016

Wolves, coyotes, and other canids are members of a diverse genus of top predators of considerable conservation and management interest. Canid howls are long-range communication signals, used both for territorial defence and group cohesion. Previous studies have shown that howls can encode individual and group identity. However, no comprehensive study has investigated the nature of variation in canid howls across the wide range of species. We analysed a database of over 2000 howls recorded from 13 different canid species and subspecies. We applied a quantitative similarity measure to compare the modulation pattern in howls from different populations, and then applied an unsupervised clusteri…

Komunikācija: Dzimtes pētījumi

2003

Does social climate influence positive eWOM? A study of heavy-users of online communities.

2018

Abstract This paper provides a deeper understanding of the role of social influences on positive eWOM behaviour (PeWOM) of heavy-users of online communities. Drawing on Social Interaction Utility Framework, Group Marketing and Social Learning Theories, we develop and test a research model integrating the interactions between the social climate of a website and Interpersonal Influences in PeWOM. 262 Spanish heavy-users of online communities were selected and the data analysed using partial least squares equation modelling. Overall, the model explains 59% of the variance of PeWOM on online communities. Findings reveal that interaction with other members of the online community (Social Presenc…

Mobile information systems - executives' view

1997

The concepts of travelling executive and executives' mobile information system are first defined in this paper. The main findings are in the form of collected data and opinions concluded from our personal discussions with 49 executives in the United Kingdom, France, Italy and Finland concerning the nature of the work of executives and the usage of information technology (IT) to support their work today. The near future expectations of the executives are also analysed, especially concerning the mobile use of IT services in order to construct executives' holistic view of mobile computing. The use of IT services was found to be very widespread. Big differences were found: some of the executive…