Search results for "broadcast"
showing 10 items of 93 documents
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…
Multicast delivery of file download services in 3G mobile networks with MBMS
2008
This article investigates the efficient transmission of file download services to several users simultaneously in 3G mobile networks with HSDPA (High-Speed Downlink Packet Access) and MBMS (Multimedia Broadcast Multicast Services). HSDPA supports high speed point-to-point (p-t-p) transmissions (up to several Mb/s), whereas with MBMS the same content can be transmitted with a point-to-multipoint (p-t-m) connection to multiple users in a unidirectional fashion. Multicast delivery can be implemented through only p-t-p transmissions with HSDPA, a single p-t-m transmission with MBMS, or using both jointly in a hybrid approach by employing HSDPA for error repair of the MBMS p-t-m transmission. We…
Priority Levels Based Multi-hop Broadcasting Method for Vehicular Ad hoc Networks
2015
International audience; This paper deals with broadcasting problem in vehicular ad hoc networks (VANETs). This communication mode is commonly used for sending safety messages and traffic information. However, designing an efficient broadcasting protocol is hard to achieve since it has to take into account some parameters related to the network environment, for example, the network density, in order to avoid causing radio interferences. In this paper, we propose a novel Autonomic Dissemination Method (ADM) which delivers messages in accordance with given priority and density levels. The proposed approach is based on two steps: an offline optimization process and an adaptation to the network …
The γd → π0 d and γd → pn Reactions in the Δ-Resonance Region
1994
Coherent pion photoproduction on the deuteron and deuteron photodisintegration in the Δ-resonance region is studied treating the final state interaction within a NN−NΔ coupled channel approach.
Soft proton exchanged channel waveguides in congruent lithium tantalate for frequency doubling
2010
We report on stable optical waveguides fabricated by soft-proton exchange in periodically-poled congruent lithium tantalate in the a-phase. The channel waveguides are characterized in the telecom wavelength range in terms of both linear properties and frequency doubling. The measurements yield a nonlinear coefficient of about 9.5pm/V, demonstrating that the nonlinear optical properties of lithium tantalate are left nearly unaltered by the process. (C) 2010 Optical Society of America
A Novel Multi-hop Broadcasting Method for VANETs Based on Autonomic Computing Paradigm
2014
One of the three best papers, Selected for the Annals of Telecommunications journal; International audience; Broadcasting is widely used in Vehicular Ad hoc Networks (VANETs) but it is hard to achieve efficiently since it depends on the network density, i.e. may cause network congestion if the protocols are not well designed. This paper introduces a novel Autonomic Dissemination Method (ADM) which delivers messages in accordance with given priority and density levels. The proposed approach is based on two steps: an offline optimization process and an online adaptation to the network characteristics. The aim is to make effective use of radio resources when there are many messages to send imu…
Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showers
2016
To exploit the full potential of radio measurements of cosmic-ray air showers at MHz frequencies, a detector timing synchronization within 1 ns is needed. Large distributed radio detector arrays such as the Auger Engineering Radio Array (AERA) rely on timing via the Global Positioning System (GPS) for the synchronization of individual detector station clocks. Unfortunately, GPS timing is expected to have an accuracy no better than about 5 ns. In practice, in particular in AERA, the GPS clocks exhibit drifts on the order of tens of ns. We developed a technique to correct for the GPS drifts, and an independent method is used to cross-check that indeed we reach a nanosecond-scale timing accura…
Coll Positioning systems: a two-dimensional approach
2006
The basic elements of Coll positioning systems (n clocks broadcasting electromagnetic signals in a n-dimensional space-time) are presented in the two-dimensional case. This simplified approach allows us to explain and to analyze the properties and interest of these relativistic positioning systems. The positioning system defined in flat metric by two geodesic clocks is analyzed. The interest of the Coll systems in gravimetry is pointed out.
Digitale Fenster für γ-γ-Koinzidenzmessungen mit Halbleiterdetektoren
1968
Zusammenfassung Digital windows have been designed and built to avoid the disadvantages of normal single channel analysers setting the gate in γ-γ-coincidence experiments with two Ge(Li)-detectors.
Hidden Oscillations in Electromechanical Systems
2016
In this paper an electromechanical system with two different types of motor is considered. It is shown that during the spin-up, the system with DC motor may experience unwanted vibration—the Sommerfeld effect. This is a well-known effect when the motor of electromechanical system gets stuck near the resonance zone instead of reaching its nominal power. The absence of this effect is demonstrated in the system with synchronous motor. Nowadays, there are many works devoted to the study of this effect in various systems. Here we discuss the Sommerfeld effect from the point of view of localization of the so-called hidden oscillations.