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1.
De Roure  D. Hall  W. 《Multimedia, IEEE》1997,4(4):68-73
The Distributed Link Service (DLS) infrastructure for linking hypertext documents on the World Wide Web complies with the open hypermedia model. In combination with link processing and management tools, we're addressing distributed information management issues. Our approach, focusing on multimedia streams and facilitating collaboration, reflects two key trends in network technology: an increase in per-user bandwidth and hosts. This corresponds to more users working with more media of increasingly different types. Open hypermedia can provide new techniques that let us take advantage of this evolution. We're extending our streaming work to HyperRadio, building on the idea that a program is actually a tour through available resources, where users can interactively follow links to other resources that interest them. By exploiting higher bandwidths and compression techniques, we can transport such “branching” material to the user. We're conducting this work with audio streams on the Internet, and plan to apply it to digital audio broadcasting  相似文献   

2.
The exponential growth of Internet use may result in a reduction of the grade of service of telecommunication networks. Capacity increase is the challenge to telecom operators. Communication satellites “see” a large customer population and provide a large: amount of-mainly entertainment-information. Interactive services are possible with enhanced communication satellite systems. Such satellite concepts and technologies are the subject of this article  相似文献   

3.
Distributed multimedia information handling and processing   总被引:1,自引:0,他引:1  
Requirements for distributed processing of multimedia information are summarized and compared with the latest efforts in standardization. An approach to a communication model that can be viewed as a special form of a model for open distributed applications is outlined. The functions of a system for the handling of multimedia information and a functional model approach, including a supporting environment, are considered. Synchronization aspects of isochronous and anisochronous communication are also outlined. The model is still under development. Detailed work needs to be done in the areas of formal specification of abstract services and modeling of communication protocols  相似文献   

4.
MultiG, an open research program addressing issues that range from end-user requirements on distributed multimedia applications supporting collaborative work to medium-access protocols for multi-gigabit networks on optical fibers, is discussed. The projects in MultiG are described from the top down, beginning with computer-supported cooperative work. Distributed multimedia applications and application generators are then considered, followed by networking issues, including interprocess communication, transport services, network protocols, and high-speed protocol processing. Testbed activities and future plans are described  相似文献   

5.
Quality of service (QOS) is increasingly important for all components within distributed multimedia systems, as this survey reveals. We discuss the QOS parameters found in communication protocols, operating systems, multimedia databases and file servers, as well as those directly affecting the human user  相似文献   

6.
Gecsei  J. 《Multimedia, IEEE》1997,4(2):58-66
The real-time requirements of continuous media call for careful resource management in distributed multimedia systems. In complex and mobile systems, however, effective resource reservation becomes almost impossible. Recent research suggests adaptive applications as a complementary solution. This article reviews heterogeneous networks and the rationale behind adaptation, gives implementation examples, and discusses some outstanding research issues  相似文献   

7.
Synchronization properties in multimedia systems   总被引:7,自引:0,他引:7  
Multimedia is defined as the integrated generation, representation, processing, storage, and dissemination of independent machine-processable information expressed in multiple time-dependent and time-independent media such as data, graphics, drawings, voice, audio, and video. The characteristics of synchronization mechanisms desirable for central and distributed multimedia systems are addressed. The concept of multimedia objects as components of an object-based model for a multimedia system is introduced. The essential new synchronization requirement is restricted blocking together with synchronization features covering real-time aspects. Existing synchronization mechanisms can be altered or new ones defined to meet these requirements  相似文献   

8.
Distributed, networked multimedia information systems will be a critical component of technology-based information infrastructures in the future. We present an infrastructure for supporting multimedia applications. We discuss various characteristics of multimedia data and the effect of the network on the required quality of presentation for multimedia data. We present a suite of synchronization protocols to support the quality of presentation. The crux of these protocols is the scheduling of multimedia information for synchronized delivery, over broadband networks with limited resources, and is identified as an NP-hard problem. We introduce two parameters which can be used to measure the performance of end-to-end synchronization protocols in a network supporting distributed multimedia applications. We propose and implement several heuristic scheduling algorithms, and compare their performance. We deduce the appropriateness of these algorithms in different types of distributed multimedia environments  相似文献   

9.
Power control in direct sequence code division multiple access (DS-CDMA) systems and power/rate allocation in multirate DS-CDMA based networks is an open and interesting research area which has attracted much attention. However, with a few exceptions, most researchers have emphasized centralized resource allocation algorithms for cellular systems where the base station keeps track of the requirements of the various users and is thus responsible for the management of network resources. Ad hoc wireless local area networks (WLANs), on the other hand, are generally configured as peer-to-peer networks with no centralized hub or controller. Thus resource allocation has to be conducted in a distributed fashion. We address the issue of distributed resource management for multirate DS-CDMA based multimedia WLANs by (1) presenting a distributed resource allocation protocol, known as distributed resource negotiation protocol (DRNP) that builds on the RTS/CTS bandwidth reservation mechanism provided by IEEE 802.111, and provides quality of service (QoS) guarantees through distributed control of resources in DS-CDMA based multimedia WLANs and (2) investigating the performance of various resource allocation schemes within the context of DRNP, in terms of network wide metrics such as overall throughput and blocking rates  相似文献   

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We evaluate the validity of the fundamental assumption behind application-specific programmable processors: that applications differ from each other in key parameters which are exploitable, such as the available instruction-level parallelism (ILP), demand on various hardware resources, and the desired mix of function units. Following the tradition of the CAD community, we develop an accurate chip area estimate and a set of aggressive hardware optimization algorithms. We follow the tradition of the architecture community by using comprehensive real-life benchmarks and production quality tools. This combination enables us to build a unique framework for system-level synthesis and to gain valuable insights about design and use of application-specific programmable processors for modern applications. We explore the application-specific programmable processor (ASSP) design space to understand the relationship between performance and area. The architecture model we used is the Hewlett Packard PA-RISC with single level caches. The system, including all memory and bus latencies, is simulated and no other specialized ALU or memory structures are being used. The experimental results reveal a number of important characteristics of the ASSP design space. For example, we found that in most cases a single programmable architecture performs similarly to a set of architectures that are tuned to individual application. A notable exception is highly cost sensitive designs, which we observe need a small number of specialized architectures that require smaller areas. Also, it is clear that there is enough parallelism in the typical media and communication applications to justify use of high number of function units. We found that the framework introduced in this paper can be very valuable in making early design decisions such as area and architectural configuration tradeoff, cache and issue width tradeoff under area constraint, and the number of branch units and issue width  相似文献   

13.
Kraak  M.-J. 《Multimedia, IEEE》1996,3(2):59-65
Developments in multimedia and scientific visualization have greatly expanded the technical capabilities of geographic information systems. Users can visually explore, analyze, and present data and gain insight on spatial relations and patterns. But how do users manage all the information that reaches them? Highly-structured interfaces such as hypermaps, discussed here, are a necessary and useful way to structure multimedia components and let users easily navigate data sets  相似文献   

14.
《IEEE network》1994,8(1):5
The authors present an overview of the January/February 1994 issue of IEEE Network which includes seven articles on distributed telecommunications systems  相似文献   

15.
A framework for the performance characterization of short-range communications systems is developed with the intention of investigating the feasibility of new multimedia wireless services at millimeter waves (MMWs). Both narrow- and wide-band systems are considered for mobile and/or fixed users. This paper aims at defining and evaluating proper metrics to characterize the service quality for the user and jointly takes the propagation characteristics, the transmission techniques, and the multiple access protocols into account. The definition of service-oriented metrics is emphasized. Three different real scenarios operating at MMW are investigated with a unified perspective: intelligent transport systems, wide-band local-area networks, and local multipoint distribution systems for interactive video services. The role played by the MMW band in the development of these services is discussed. In each scenario, accurate propagation analysis is carried out and suitable countermeasure techniques are pointed out in order to join suitable service-quality levels. The methodology considered is based on both analytical and semianalytical tools for performance evaluation  相似文献   

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17.
Power control for wireless multimedia CDMA systems   总被引:3,自引:0,他引:3  
In a wireless multimedia communication system where different types of traffic such as speech, data, and video have different data rates, good power control for individual traffic can ensure quality of service (QoS) and achieve a better throughput at the same time. The authors propose a closed-form power control function based on a parameter called the traffic exponent that simplifies the power control processing and improves the overall CDMA system performance  相似文献   

18.
We present a policy for handling multimedia traffic over satellite air interfaces. It extends the advantages of ATM to satellite by the statistical multiplexing of variable-rate traffic sources. Effectiveness is assessed within a multimedia satellite platform called EuroSkyWay, based on Ka-band payload and on-board processing  相似文献   

19.
Ikedo  T. 《Multimedia, IEEE》2002,9(4):56-72
Multimedia environments need systems with better performance to meet the growing demands for more realism. Ultra-large-scale integration will eventually make possible the advanced, real-time graphic rendering technology that such digital imagery requires. The hardware-only architecture prototype discussed in this article presents a possible solution  相似文献   

20.
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