Search results for "computer networks"
showing 10 items of 860 documents
Optimizing H.264/AVC interprediction on a GPU-based framework
2011
H.264/MPEG-4 part 10 is the latest standard for video compression and promises a significant advance in terms of quality and distortion compared with the commercial standards currently most in use such as MPEG-2 or MPEG-4. To achieve this better performance, H.264 adopts a large number of new/improved compression techniques compared with previous standards, albeit at the expense of higher computational complexity. In addition, in recent years new hardware accelerators have emerged, such as graphics processing units (GPUs), which provide a new opportunity to reduce complexity for a large variety of algorithms. However, current GPUs suffer from higher power consumption requirements because of…
Dependability-Based Reliability Analysis in URC Networks: Availability in the Space Domain
2019
Ultra-reliable low latency communication (URLLC), which refers to achieving almost 100% reliability at a certain (satisfactory) level of services and stringent latency, is one of the key requirements for 5G networks. However, most prior studies on reliable communication did not address space domain analysis. Neither were they pursued from a dependability perspective. This paper addresses the ultra-reliable communication (URC) aspect of URLLC and aims at advocating the concept of URC from a dependability perspective in the space domain. We perform in-depth analysis on URC considering both the spatial characteristics of cell deployment and user distributions, as well as service requirements. …
System Times and Channel Availability for Secondary Transmissions in CRNs: A Dependability Theory based Analysis
2017
[EN] Reliability is of fundamental importance for the performance of secondary networks in cognitive radio networks (CRNs). To date, most studies have focused on predicting reliability parameters based on prior statistics of traffic patterns from user behavior. In this paper, we define a few reliability metrics for channel access in multichannel CRNs that are analogous to the concepts of reliability and availability in classical dependability theory. Continuous-time Markov chains are employed to model channel available and unavailable time intervals based on channel occupancy status. The impact on user access opportunities based on channel availability is investigated by analyzing the stead…
Restrictions on data-driven political micro-targeting in Germany
2017
The revitalisation of canvassing in recent elections is strongly related to campaigns´ growing possibilities for analysing voter data to gain knowledge about their constituents, identifying their most likely voters and serving up personalised messages through individual conversations. The research literature about political micro-targeting hardly ever focusses on campaigns in parliamentary democracies with strict data protection laws. Based on in-depth expert interviews we introduce a framework of constraints in strategic political communication and reveal several restrictions on the macro, meso and micro levels which hinder the implementation of sophisticated data strategies in Germany. We…
Online Black-Markets: An Investigation of a Digital Infrastructure in the Dark
2021
AbstractThis paper investigates the functioning of Online Black-Markets (OBMs), i.e. a digital infrastructure operating in the Dark Net that enables the exchange of illegal goods such as drugs, weapons and fake digital identities. OBMs exist notwithstanding adverse conditions such as police interventions, scams and market breakdowns. Relying on a longitudinal case study, we focus on the dynamics of interactions among actors and marketplace technologies and we identify three mechanisms explaining OBMs operations. In particular, we show that OBMs infrastructure is the result of commoditization, platformization and resilience processes. Our contribution relies on the identification of communit…
Online pricing for demand-side management in a low-voltage resistive micro-grid via a Stackelberg game with incentive strategies
2022
It has been demonstrated that online pricing mechanisms are a viable solution for demand side management in power systems. This study deals with the analysis and design of a droop-controlled low-voltage resistive AC micro-grid network system. Such a system is subjected to a dynamic demand obtained from an online pricing mechanism, which is proposed as a novelty in the study of micro-grids. This mechanism is derived from a variation of the Stackelberg game, which includes the use of incentive strategies. First, a configuration in which a supplier announces an incentive function and (Formula presented.) -consumers’ reaction to the resulting personalised price is presented. Then, a detailed st…
“Your ride has arrived” – Exploring the nexus between subjective well-being, socio-cultural beliefs, COVID-19, and the sharing economy
2021
This study aimed to identify and explain different facets of the sharing economy and to differentiate between micro- and macro-mobility services. We also aimed to examine the correlation between the sharing economy and subjective well-being, cultural beliefs, and COVID-19. An exploratory research technique with face-to-face semi-structured interviews was used to collect data from a sample of 22 rideshare app users in a developing country between January and May 2020 and in July 2020. The data were analyzed using the NVivo 12 application. The major findings suggest that, considering their scope and use, sharing economy technology and services can be divided into four major domains: (1) hospi…
Mobility and Spatio-Temporal Exposure Control
2013
Modern risk assessment methods cover many issues and encompass both risk analysis and corresponding prevention/mitigation measures.However, there is still room for improvement and one aspect that may benefit from more work is “exposure control”.The “exposure” an asset experiences plays an important part in the risks facing the asset.Amongst the aspects that all too regularly get exposed is user identities and user location information,and in a context with mobile subscriber and mobility in the service hosting (VM migration/mobility) the problems associated with lost identity/location privacy becomes urgent.In this paper we look at “exposure control” as a way for analyzing and protecting use…
Attention Shaping and Software Risk—A Categorical Analysis of Four Classical Risk Management Approaches
1998
This paper examines software risk management in a novel way, emphasizing the ways in which managers address software risks through sequential attention shaping and intervention. Software risks are interpreted as incongruent states within a socio-technical model of organizational change that includes task, structure, technology, and actors. Such incongruence can lead to failures in developing or implementing the system and thus to major losses. Based on this model we synthesize a set of software risk factors and risk resolution techniques, which cover the socio-technical components and their interactions. We use the model to analyze how four classical risk management approaches—McFarlan's p…
Packet management techniques for measurement based end-to-end admission control in IP networks
2000
End-to-end Measurement Based connection Admission Control (EMBAC) mechanisms have been proposed to support real-time flows quality of service requirements over a Differentiated Services Internet architecture. The EMBAC basic idea is to decentralize the admission control decision, by requiring each individual user to probe the network path during flow setup, and by basing the accept/reject decision on the probing traffic statistics measured at the destination. In conformance with the differentiated services framework, routers are oblivious to individual flows and only need to serve data packets with a higher priority than probing traffic. In this paper, we build upon the observation that som…