7,990 research outputs found
The Design of a System Architecture for Mobile Multimedia Computers
This chapter discusses the system architecture of a portable computer, called Mobile Digital Companion, which provides support for handling multimedia applications energy efficiently. Because battery life is limited and battery weight is an important factor for the size and the weight of the Mobile Digital Companion, energy management plays a crucial role in the architecture. As the Companion must remain usable in a variety of environments, it has to be flexible and adaptable to various operating conditions. The Mobile Digital Companion has an unconventional architecture that saves energy by using system decomposition at different levels of the architecture and exploits locality of reference with dedicated, optimised modules. The approach is based on dedicated functionality and the extensive use of energy reduction techniques at all levels of system design. The system has an architecture with a general-purpose processor accompanied by a set of heterogeneous autonomous programmable modules, each providing an energy efficient implementation of dedicated tasks. A reconfigurable internal communication network switch exploits locality of reference and eliminates wasteful data copies
Semantic multimedia remote display for mobile thin clients
Current remote display technologies for mobile thin clients convert practically all types of graphical content into sequences of images rendered by the client. Consequently, important information concerning the content semantics is lost. The present paper goes beyond this bottleneck by developing a semantic multimedia remote display. The principle consists of representing the graphical content as a real-time interactive multimedia scene graph. The underlying architecture features novel components for scene-graph creation and management, as well as for user interactivity handling. The experimental setup considers the Linux X windows system and BiFS/LASeR multimedia scene technologies on the server and client sides, respectively. The implemented solution was benchmarked against currently deployed solutions (VNC and Microsoft-RDP), by considering text editing and WWW browsing applications. The quantitative assessments demonstrate: (1) visual quality expressed by seven objective metrics, e.g., PSNR values between 30 and 42 dB or SSIM values larger than 0.9999; (2) downlink bandwidth gain factors ranging from 2 to 60; (3) real-time user event management expressed by network round-trip time reduction by factors of 4-6 and by uplink bandwidth gain factors from 3 to 10; (4) feasible CPU activity, larger than in the RDP case but reduced by a factor of 1.5 with respect to the VNC-HEXTILE
Demonstrating the feasibility of standardized application program interfaces that will allow mobile/portable terminals to receive services combining UMTS and DVB-T
Crucial to the commercial exploitation of any service combining UMTS and DVB-T is the availability of standardized APIâs adapted to the hybrid UMTS and DVB-T network and to the technical limitations of mobile/portable terminals. This paper describes work carried out in the European Commission Framework Program 5 (FP5) project CONFLUENT to demonstrate the feasibility of such Application Program Interfaces (APIâs) by enabling the reception of a Multimedia Home Platform (MHP) based application transmitted over DVB-T on five different terminals with parts of the service running on a mobile phone
DyPS: Dynamic Processor Switching for Energy-Aware Video Decoding on Multi-core SoCs
In addition to General Purpose Processors (GPP), Multicore SoCs equipping
modern mobile devices contain specialized Digital Signal Processor designed
with the aim to provide better performance and low energy consumption
properties. However, the experimental measurements we have achieved revealed
that system overhead, in case of DSP video decoding, causes drastic
performances drop and energy efficiency as compared to the GPP decoding. This
paper describes DyPS, a new approach for energy-aware processor switching (GPP
or DSP) according to the video quality . We show the pertinence of our solution
in the context of adaptive video decoding and describe an implementation on an
embedded Linux operating system with the help of the GStreamer framework. A
simple case study showed that DyPS achieves 30% energy saving while sustaining
the decoding performanc
Analysis and Simulation of the Signals Transmission in the DVB-H/SH Standards
Tato disertaÄnĂ prĂĄce se zabĂœvĂĄ analĂœzou, simulacĂ a mÄĆenĂm zpracovĂĄnĂ a pĆenosu signĂĄlĆŻ digitĂĄlnĂ televize pro pĆĂjem mobilnĂho TV vysĂlĂĄnĂ ve standardech DVB-H a DVB-SH. Tyto standardy vychĂĄzejĂ z pĆedpokladu, ĆŸe pĆĂjem signĂĄlu je charakterizovĂĄn modely pĆenosovĂœch kanĂĄlĆŻ s vĂcecestnĂœm ĆĄĂĆenĂm. Tyto, tzv. ĂșnikovĂ© kanĂĄly, jsou charakterizovĂĄny hlavnÄ zpoĆŸdÄnĂm a ziskem jednotlivĂœch cest. V zĂĄvislosti na dalĆĄĂch parametrech (rychlost pĆijĂmaÄe, DopplerovskĂ© spektrum), je moĆŸnĂ© rozdÄlit ĂșnikovĂ© kanĂĄly do tĆech hlavnĂch skupin: mobilnĂ, pĆenosnĂ© a fixnĂ. DĂĄ se pĆedpoklĂĄdat, ĆŸe v rĆŻznĂœch modelech kanĂĄlĆŻ bude pĆenĂĄĆĄenĂœ signĂĄl rĆŻznÄ ovlivnÄn. Proto je potĆebnĂ© najĂt optimĂĄlnĂ parametry systĂ©mĆŻ (DVB-H/SH) pro kvalitnĂ pĆĂjem vysĂlanĂœch sluĆŸeb mobilnĂ televize, coĆŸ je hlavnĂm cĂlem tĂ©to disertaÄnĂ prĂĄci. Pro tento ĂșÄel byly vytvoĆeny dvÄ vhodnĂ© aplikace (jedna pro DVB-H a jedna pro DVB-SH) s GUI v prostĆedĂ MATLAB, kterĂ© umoĆŸĆujĂ simulovat a analyzovat mĂru zkreslenĂ signĂĄlu v pĆĂpadÄ mobilnĂch, pĆenosnĂœch a fixnĂch scĂ©nĂĄĆĆŻ pĆenosu. NavĂc, tyto aplikace obsahujĂ i druhĂœ samostatnĂœ simulĂĄtor pro nastavenĂ a modifikaci parametrĆŻ jednotlivĂœch pĆenosovĂœch cest. DĂky tomu je moĆŸnĂ© zhodnotit vliv parametrĆŻ celĂ©ho systĂ©mu a kanĂĄlovĂœch modelĆŻ na dosaĆŸenou chybovost (BER a MER) a kvalitu pĆenosu. Ve vĆĄech pĆenosovĂœch scĂ©nĂĄĆĂch (v zĂĄvislosti na pomÄru C/N) byly zĂskanĂ©, vyhodnocenĂ© a diskutovanĂ© zkreslenĂ signĂĄlĆŻ. NavĂc, u standardu DVB-H, vĆĄechny zĂskanĂ© vĂœsledky ze simulacĂ byly ovÄĆeny mÄĆenĂm. RozdĂly mezi dosaĆŸenĂœmi vĂœsledky (simulace a mÄĆenĂ) byly rovnÄĆŸ podrobeny diskuzi. Tuto disertaÄnĂ prĂĄci je moĆŸnĂ© rozdÄlit do ÄtyĆ hlavnĂch ÄĂĄstĂ. PrvnĂ ÄĂĄst disertaÄnĂ prĂĄce se zabĂœvĂĄ reĆĄerĆĄĂ souÄasnĂ©ho vĂœvoje v oblasti digitĂĄlnĂho televiznĂho vysĂlĂĄnĂ na mobilnĂ terminĂĄly ve standardech DVB-H/SH. Na konci tĂ©to ÄĂĄsti jsou jasnÄ popsĂĄny cĂle tĂ©to disertaÄnĂ prĂĄce. DruhĂĄ ÄĂĄst prĂĄce je zamÄĆenĂĄ na struÄnĂœ popis blokovĂ©ho diagramu vysĂlaÄĆŻ v obou standardech DVB-H/SH. DĂĄle jsou struÄnÄ popsĂĄny modely pĆenosovĂœch kanĂĄlĆŻ, kterĂ© se pouĆŸĂvajĂ pro modelovĂĄnĂ pĆenosu signĂĄlu. StruÄnĂœ popis vytvoĆenĂœch aplikacĂ, i s vĂœvojovĂœm diagramem, kterĂ© jsou vhodnĂ© pro simulaci a analĂœzu pĆenosu v DVB-H/SH, jsou popsĂĄny v tĆetĂ ÄĂĄsti prĂĄce. ÄtvrtĂĄ a nejdelĆĄĂ ÄĂĄst tĂ©to disertaÄnĂ prĂĄce se zabĂœvĂĄ vyhodnocenĂm zĂskanĂœch vĂœsledkĆŻ ze simulacĂ a mÄĆenĂ.This dissertation thesis deals with the analysis, simulation and measurement of the signal processing and transmission in DVB-H and DVB-SH standards. These standards are based on the assumption that signal reception is characterized by the transmission channels with echoes. These, so called fading channels, are mainly characterized by the path delays and path losses. Depending on the other, additional features (speed of the receiver, Doppler spectrum, etc.), it can be possible divided these channels onto three main groups: mobile, portable and fixed. Of course, signal transmission in different transmission channel models are affected differently. Therefore, it is needed found the optimal system parameters in both, DVB-H and DVB-SH standards, for the quality reception of the broadcasted mobile TV services, which is the main goal of this thesis. For this purpose, two appropriate applications (one for DVB-H and one for DVB-SH) with GUI were created in MATLAB, which enable simulated and analyzed the signal distortions in mobile, portable and fixed transmission scenarios. Moreover, these applications also contain a second application with GUI for the easy set and modification of the parameters of the used channel models. Therefore, it is possible to evaluate the effect of parameters of whole system and channel models on the achieved error rate (BER and MER) and quality of the transmission. In all mentioned transmission scenarios, the signal distortions (depending on the Carrier-to-Noise ratio) were obtained, evaluated and discussed in this dissertation thesis. Furthermore, in case of DVB-H, all obtained results from the simulations, were verified by the measuring. Differences between the obtained results (simulation and measuring) are also discussed. This dissertation thesis can be divided into four main parts. The first part of this dissertation thesis, after the short introduction, deals with present state-of-the-art and literature survey in mobile broadcast DVB-H/SH standards. At the end of this part are clearly outlined the main aims of this dissertation thesis. Second part is focused on the brief description of the functional block diagram of transmitters in both, DVB-H/SH standards. Furthermore, there are briefly described the transmission fading channel models, which are commonly used for the modeling of the signal transmission. The brief description of program applications with flowcharts, appropriate for the simulation of the transmission in the DVB-H/SH standards, are presented and described in the third part of this thesis. Finally, the fourth and longest part of this thesis is focused on the evaluation and comparison of obtained results from the simulations and measurements.
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Optimized mobile thin clients through a MPEG-4 BiFS semantic remote display framework
According to the thin client computing principle, the user interface is physically separated from the application logic. In practice only a viewer component is executed on the client device, rendering the display updates received from the distant application server and capturing the user interaction. Existing remote display frameworks are not optimized to encode the complex scenes of modern applications, which are composed of objects with very diverse graphical characteristics. In order to tackle this challenge, we propose to transfer to the client, in addition to the binary encoded objects, semantic information about the characteristics of each object. Through this semantic knowledge, the client is enabled to react autonomously on user input and does not have to wait for the display update from the server. Resulting in a reduction of the interaction latency and a mitigation of the bursty remote display traffic pattern, the presented framework is of particular interest in a wireless context, where the bandwidth is limited and expensive. In this paper, we describe a generic architecture of a semantic remote display framework. Furthermore, we have developed a prototype using the MPEG-4 Binary Format for Scenes to convey the semantic information to the client. We experimentally compare the bandwidth consumption of MPEG-4 BiFS with existing, non-semantic, remote display frameworks. In a text editing scenario, we realize an average reduction of 23% of the data peaks that are observed in remote display protocol traffic
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