Search results for "Telecommunication"
showing 10 items of 1769 documents
Hardware Implementation of a Configurable Motion Estimator for Adjusting the Video Coding Performances
2012
International audience; Despite the diversity of video compression standard, the motion estimation still remains a key process which is used in most of them. Moreover, the required coding performances (bit-rate, PSNR, image spatial resolution, etc.) depend obviously of the application, the environment and the network communication. The motion estimation can therefore be adapted to fit with these performances. Meanwhile, the real time encoding is required in many applications. In order to reach this goal, we propose in this paper a hardware implementation of the motion estimator which enables the integer motion search algorithms to be modified and the fractional search and variable block siz…
Efficient formulation of Multimode Equivalent Networks for 2-D waveguide steps through Kummer's transformation
2017
In this paper we present a new and improved formulation for the Multimode Equivalent Network (MEN) representation of arbitrary waveguide junctions. In the new formulation the Kummer's transformation is used to separate the kernel into dynamic and static parts, by introducing higher order extraction terms. The main difference with respect to the old formulation is that the approximation of the kernel is more accurate and the numerical computations are more efficient. In addition to theory, both formulations are compared in terms of efficiency and convergence thereby fully validating the proposed new formulation.
A fiber-based limiter at 170 Gbit/s for all-optical regeneration
2009
We report the numerical and experimental studies of a spectrally filtered fiber-based optical limiter at 170 Gbit/s. The device, including less than 1 km-long of highly nonlinear optical fiber and a 3 nm-width filter, exhibits good performance at an average input power of 14.5 dBm. No power penalty has been observed and a strong robustness against optical noise has been demonstrated.
Enabling Retransmissions for Achieving Reliable Multicast Communications in WSNs
2016
To ensure end-to-end reliable multicast or broadcast transmissions in IEEE 802.15.4 based wireless sensor networks WSNs) is a challenging task since no retransmission and acknowledgment mechanisms are defined in such WSNs. In this paper, we propose three retransmission enabled multicast transmission schemes in order to achieve reliable packet transmissions in such networks. Different from the legacy CSMA/CA principle, these schemes allow a sending or forwarding node to retransmit a packet if necessary and enable implicit or/and explicit acknowledgment for multicast services. Simulations are performed in order to assess the performance of these schemes in terms of number of retransmissions, …
Priority-oriented multicast transmission schemes for heterogeneous traffic in WSNs
2016
To ensure quality of service (QoS) for heterogeneous traffic in IEEE 802.15.4 based wireless sensor networks (WSNs) is a challenging task since no traffic prioritization mechanism is defined in such WSNs. In this paper, we propose two priority-oriented multicast transmission schemes to provide QoS for heterogeneous traffic in WSNs. Contrary to the legacy CSMA/CA and FIFO principles, these schemes differentiate self-generated or received traffic and give priority to delay-sensitive traffic with respect to channel access and packet scheduling. Simulations are performed in order to assess the performance of these schemes in terms of end-to-end delay, energy consumption, packet delivery ratio, …
Multicast TV over WLAN in a University Campus Network
2009
One of the multimedia services offered by the campus network of the Polytechnic University of Valencia is TV over IP. This service works well in the devices connected directly to the wired network but we have detected some problems when the receivers access to the campus network through wireless IEEE 802.11, especially when devices roam across the Campus. In this paper we propose and evaluate a server-based solution to minimize the packet loss and reduce the lack of service when the mobile devices roam from an Access Point to another Access Point in the wireless network. This solution uses a location system to modify the behaviour of standard multicasting protocols in order to get a near-se…
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…
SMAA in Robustness Analysis
2016
Stochastic multicriteria acceptability analysis (SMAA) is a simulation based method for discrete multicriteria decision aiding problems where information is uncertain, imprecise, or partially missing. In SMAA, different kind of uncertain information is represented by probability distributions. Because SMAA considers simultaneously the uncertainty in all parameters, it is particularly useful for robustness analysis. Depending on the problem setting, SMAA determines all possible rankings or classifications for the alternatives, and quantifies the possible results in terms of probabilities. This chapter describes SMAA in robustness analysis using a real-life decision problem as an example. Bas…
Estimation techniques to measure subjective quality on live video streaming in Cloud Mobile Media services
2018
Abstract The adoption of smart phones, the increased access to mobile broadband networks and the availability of public cloud infrastructures are aligning to the next generation of truly ubiquitous multimedia services, known as Cloud Mobile Media (CMM) services offering mobile video. Nevertheless, due to an inherit higher and variable end to end delay mainly as a result of the virtualization process, new challenges appear. One challenge is given by live video streaming applications when trying to keep a good Quality of Experience of the delivered video, measured in terms of a subjective video quality metric, named Mean Opinion Score (MOS). Our goal is to estimate and predict this subjective…
KIND-DAMA: A modular middleware for Kinect-like device data management
2017
Summary In the last decades, we have witnessed a growing interest toward touchless gestural user interfaces. Among other reasons, this is due to the large availability of different low-cost gesture acquisition hardware (the so-called “Kinect-like devices”). As a consequence, there is a growing need for solutions that allow to easily integrate such devices within actual systems. In this paper, we present KIND-DAMA, an open and modular middleware that helps in the development of interactive applications based on gestural input. We first review the existing middlewares for gestural data management. Then, we describe the proposed architecture and compare its features against the existing simila…