Search results for "Computer network"
showing 10 items of 1634 documents
Improved support for streaming services in vehicular networks
2004
This paper presents a resource management mechanism aimed at improving the effectiveness of streaming services in vehicular networks. The scenario considered in this paper is that of a group of customers located into a same public vehicle, e.g. a moving train connected to the network via a satellite link, and requesting either video-on-demand-like services, as well as real-time diffusive (broadcast) streaming services. We show that a proxy server, devised to introduce an elastic buffer aimed at decoupling the information retrieval download speed on the outer network from the natural play-out speed used in the vehicular network, results to be an extremely effective approach in reducing the o…
On the Provisioning of Mobile Digital Terrestrial TV Services to Vehicles With DVB-T
2012
[EN] Most of the DVB-T (Digital Video Broadcasting -Terrestrial) networks deployments worldwide have been designed for fixed rooftop antennas and high transmission capacity, not providing good coverage level for vehicular mobile reception. This letter analyzes how to combine different technical solutions, so far studied individually, in order to increase the robustness of the transmission for vehicular reception to provide in-band mobile services. In particular, we consider: receive antenna diversity, hierarchical modulation, and Application Layer Forward Error Correction (AL-FEC). Performance evaluation results have been obtained by means of simulations, laboratory tests, and field measure…
Mobile radio channel models for present and future wireless communication systems
2008
From the beginnings of mobile communication, there is a high demand for realistic models for mobile fading channels. The reason for the demand is that channel models are essential for the performance evaluation, parameter optimisation, and test of mobile communication systems. Design methods for mobile fading channels are therefore of great importance for system engineers who are involved in the development of present and future mobile communication systems. In this presentation, an overview will be given about several design methodologies commonly used for the design of mobile radio channel models in present and future wireless communication systems. All presented channel models have in co…
An efficient Chinese remainder theorem based node capture resilience scheme for Mobile WSNs
2010
Node capture attack is a critical issue in Mobile WSNs where attacker-controlled replicas may act maliciously. In this paper, we present a novel Chinese remainder theorem based node capture resilience scheme that can be utilized to discover and revoke captured nodes. Moreover, our scheme can limit the ability of captured nodes to further compromise forward security, backward security, and launch collusion attacks. Detailed analysis shows that our scheme indeed achieves the expected design goals.
Modeling of mobility and groups in inter-vehicular MANET-based networks
2007
This paper evaluates the behavior of mobile ad hoc networks when group mobility is involved. We concentrate on group mobility because road vehicles tend to form groups or fleets whose behavior depends on the behavior of the close-by vehicles. We propose four different group mobility models and present a mobility pattern generator, called grcmob that we designed to be used with the ns-2 simulator. We evaluate the performance of vehicular ad hoc networks under a wide number of scenarios using both TCP and UDP data traffic. We show that the number of groups is more important than the number of nodes and that the impact of area size is almost negligible. We also reveal that the mixture of inter…
MCMIPv6: Multicast Configuration-based Mobile IPv6 protocol
2010
International audience; Mobile IPv6 (MIPv6) and its basic extension for network mobility NEMO were initially designed to manage the mobility of device users and networks respectively while maintaining a permanent IP address. Nevertheless, the different MIPv6's experiments have shown many lacks in case of high mobility of nodes such as in vehicular networks. To overcome these lacks, many solutions have been proposed by the research community. The most famous ones are HMIPv6 and FMIPv6 tackling each a specific issue. On the one hand, FMIPv6 introduces a solution to effectively minimize the L2/L3 latency and avoid the packets losses during the handover procedure. On the other hand, HMIPv6 is e…
Group mobility impact over TCP and CBR traffic in mobile ad hoc networks
2004
We present an analysis of the effect that mobility models have over the performance of a mobile ad hoc network. We concentrate on group mobility because there is a growing attention on the development and evaluation of MANET's approach applied to personal area networks (PANs), especially based on Bluetooth technology. We investigate the effect that the mobility model has on the performance of CBR traffic and TCP traffic. We propose four different group mobility models and describe a mobility pattern generator called grcmob to be used with the ns-2 simulator. We perform a thorough evaluation of a MANET behavior using as a reference the behavior obtained with the random waypoint mobility mode…
Network Connectivity and Area Coverage for UAV Fleet Mobility Model with Energy Constraint
2016
International audience; Our main focus through the present paper is on developing an original distributed mobility model for autonomous fleet of interconnected UAVs (Unmanned Aerial Vehicles) performing an area exploration mission. The UAVs, equipped with wireless ad-hoc capabilities, are required to optimally explore an area while maintaining connectivity with their neighboring UAVs and the base station. Because energy is a scarce resource, especially for UAVs, its wise management is quite beneficial for the network lifetime and mission success. Hence, the proposed mobility model, compared to other models in the literature, is the first to ever include the remaining energy level as decisio…
Smart drugs: de la terapia al transhumanismo
2018
ABSTRACT Enhancing human cognitive capacities is one of the central axes of transhumanist proposals. In recent decades, halfway between the actual and the possible, another way of approaching human mind enhancement has appeared: smart drugs —also known as cognitive enhancers or nootropics— psychopharmaceuticals that promise an improvement in cognition, memory, intelligence, attention, concentration... These drugs are currently used in the therapeutic field, but many think that the barriers between therapy and human enhancement are fading away. This paper presents three smart drugs —methylphenidate, modafinil and pyracetam— and reflects on the limits between therapy and enhancement, placing …
Verification of JADE Agents Using ATL Model Checking
2015
It is widely accepted that the key to successfully developing a system is to produce a thorough system specification and design. This task requires an appropriate formal method and a suitable tool to determine whether or not an implementation conforms to the specifications. In this paper we present an advanced technique to analyse, design and debug JADE software agents, using Alternating-time Temporal Logic (ATL) which is interpreted over concurrent game structures, considered as natural models for compositions of open systems. In development of the proposed solution, we will use our original ATL model checker. In contrast to previous approaches, our tool permits an interactive or programma…