Large-capacity multimedia systems

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     

Distributed multimedia systems

A distributed multimedia system (DMS) is an integrated communication, computing, and information system that enables the processing, management, delivery, and presentation of synchronized multimedia information with quality-of-service guarantees. Multimedia information may include discrete media data, such as text, data, and images, and continuous media data, such as video and audio. Such a system enhances human communications by exploiting both visual and aural senses and provides the ultimate flexibility in work and entertainment, allowing one to collaborate with remote participants, view movies on demand, access on-line digital libraries from the desktop, and so forth. In this paper, we present a technical survey of a DMS. We give an overview of distributed multimedia systems, examine the fundamental concept of digital media, identify the applications, and survey the important enabling technologies     

Distributed multimedia information systems

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     

Quality-based evaluation of multimedia synchronization protocolsfor distributed multimedia information systems

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     

Adaptation in distributed multimedia systems

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     

Synchronization properties in multimedia systems

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     

Integrating multimedia in geographical information systems

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     

Single-receiver diversity systems

Diversity reception techniques can help to combat fast fading in urban areas, and this paper describes some predetection combining systems designed to be compatible with existing standard receivers. Quantitative results show that a worthwhile improvement in quality of reception can be Obtained with small numbers of antennas. There are advantages to be gained if, in future receiving systems, the diversity technique is incorporated directly into the receiver design.     

Creating realistic scenes in future multimedia systems

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     

Power control for wireless multimedia CDMA systems

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     

Millimeter waves for short-range multimedia communication systems

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     

QoS for multimedia applications in satellite systems

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     

An architecture for real-time multimedia communication systems

A multimedia communication system includes both the communication protocols used to transport the real-time data and the distributed computing system (DCS) within which any applications using the protocols must execute. The architecture presented attempts to integrate these communications protocols with the DCS in a smooth fashion in order to ease the writing of multimedia applications. Two issues are identified as being essential to the success of this integration: the synchronization of related real-time data streams, and the management of heterogeneous multimedia hardware. The synchronization problem is tackled by defining explicit synchronization properties at the presentation level and by providing control and synchronization operations within the DCS which operate in terms of these properties. The heterogeneity problems are addressed by separating the data transport semantics (protocols themselves) from the control semantics (protocol interfaces)     

Performance of wideband CDMA systems supporting multimedia traffic

We evaluate the performance of wideband CDMA cellular systems providing different classes of multimedia traffic and supporting user mobility. A Markovian teletraffic model of the user dynamics is developed. Constraints are imposed in the model which account for the multiple access interference among active users. Results are shown in terms of call blocking probabilities and average number of active connections. The methodology proposed is a useful tool for the design and planning of third generation cellular systems     

High-throughput multiple-input multipleoutput systems for in-home multimedia streaming

Wireless communication systems based on multiple-input multiple-output (MIMO) technology have the potential to achieve increased spectral efficiency with no additional transmit power or bandwidth requirements. This can be achieved by exploiting the spatial subchannels between the multiple transmit and receive elements. The enhanced performance of MIMO technology makes it a strong candidate for ad hoc systems requiring very high throughput, such as high-definition multimedia streaming in the home. In this article we compare the performance of conventional and newly proposed MIMO architectures for such applications. Specifically designed antenna arrays are proposed as a solution to significantly reduced MIMO performance in line-of-sight (LoS) conditions. To help in the design of such systems, the criterion for achieving maximum MIMO capacity in LoS is presented as a function of the transmitter-to-receiver separation distance, the array orientation and the element spacings. The performance of the LoS-enhanced proposal and the conventional system is quantified in terms of the channel capacity, the packet error rate (PER) and the throughput by employing a MIMO-enabled WLAN physical layer simulator. The results from MIMO measurements performed inside an anechoic chamber and in an indoor environment are presented to validate the theoretic predictions