Impact of Multimedia Traffic Characteristics on ATM Network Configuration

This paper proposes a new topological designmethod, named BXCQ, which optimizes logical networkconfiguration while guaranteeing Quality-of-Service(QoS) requirements for each service class in an ATMnetwork. The BXCQ method determines the optimum logicalnetwork topology associated with each service class soas to minimize network cost. In our previously proposedFull-Net architecture these different logical topologies can be suitably mapped at the sametime on the same ATM physical network by using theVirtual Channel Handler (VCH) to create differentlogical interconnection networks. The BXCQ method allows us to clarify the relations between multimediatraffic characteristics and desirable logical networkconfigurations in Full-Net. Evaluation results suggestthat a service class that is bursty, delay tolerant, and cell loss sensitive with small demandshould be supported by a loop-like topology. This studywill be useful for designing flexible and cost-effectivemultimedia networks that can also adapt to not-yet-known services.     

A Generic Architecture Multimedia Service and Management

A multimedia service architecture is constructedby using a generic component model. In order to derivespecific components, a generic service agent and genericservice component architectures are developed. Using generic agent and the service components,a TINA-C conformant object-oriented hierarchical genericservice component is developed and presented. As anexample, a multimedia QoS service and management architecture is presented.     

IPv4/IPv6混合网中基于SIP协议数据传输的设计与实现

介绍了IPv4向IPv6过渡方案,提出了IPv4/IPv6混合网络中SIP通信解决方案并进行了实现,解决了混合网络环境下SIP数据传输问题应用层协议与网络层不适配问题.     

High Speed Shutters

The principles of single-shot high speed shutters are outlined including (lash, capping, electro-optic (Faraday and Kerr Cell) and image tube techniques. The limitations of transmission and response time are compared.     

Optical Character Generation for a High-Speed Non-Impact Printer

The requirements for optical character generation for a commercial electrophotographic high-speed printer—more than 10,000 1pm—are given. They lead to the conclusion that the principal elements of a character generator will he a laser, an acousto-optic deflector and a polygon mirror.

The arrangement of a character generator which has been realized in a commercial printer is described in detail. Its performance characteristics are calculated and compared to experimental results.     

Procedure Based Program Compression

Cost and power consumption are two of the most important design factors for many embedded systems, particularly consumer devices. Products such as Personal Digital Assistants, pagers with integrated data services, and smart phones have fixed performance requirements but unlimited appetites for reduced cost and increased battery life. Program compression is one technique that can be used to attack both of these problems. Compressed programs require less memory, thus reducing the cost of both direct materials and manufacturing. Furthermore, by relying on compressed memory, the total number of memory references is reduced. This reduction saves power by lowering the traffic on high capacitance buses. This paper will discuss a new approach to implementing transparent program compression that requires little or no hardware support. Procedures are compressed individually, and a directory structure is used to bind them together at runtime. Decompressed procedures are explicitly cached in ordinary RAM as complete units, thus resolving references within each procedure. This approach has been evaluated on a set of 25 embedded multimedia and communications applications, and results in an average memory reduction of 40% with a runtime performance overhead of 10%.     

The Role Multimedia of Multicasting in Managing Interactive Distance Learning Systems

This paper discusses the important role ofmulticasting in designing, implementing, and managinginteractive multimedia distance learning systems. Thisis achieved in the context of IRI, an Interactive Remote Instruction system for distance learningbuilt at Old Dominion University. IRI is anInternet-based system which integrates continuousmultimedia, shared applications and a variety ofmulti-user collaborative utilities. In this paper, weconcentrate on the process architecture and dynamicmulticast group handling as they pertain to managingmultimedia resources, and show how they supportrobustness and short response time to user actions. IRIuses raw IP multicasting for audio and video streams andreliable multicasting for resource management and datasharing. The system is scalable (uses multicast for inter-process communication) andexpandable(partitioned into a setofautonomousbutcooperating components).     

A Novel Multiaccess Strategy for Multimedia Wireless LANs

The main focus of the research presented in thispaper is to evaluate how efficiently a commoncommunication medium such as broadcast radio can beshared by a large number of network devices in anin-building environment. The goal is to recommend anoptimal method to fulfil the demanding requirementsdictated by broadband multimedia applications operatingin wireless local area networks. To this end, apractical and efficient multiaccess scheme calledreserved polling is proposed and analyzed.It is shown that the new method is able to handle anintegrated mix of multimedia traffic and operaterobustly in an unreliable wireless transport medium. Ananalytical approach based on queueing theory is employedto gain some insight into the complex behavior of theprotocol. This approach appears to be accurate in predicting its performance for both bursty andperiodic traffic types. The analytical results areverified by network simulation.     

Managing Multimedia Network Services

In this paper we present a novel approach tomanaging real-time traffic in multimedia networks. Wefirst clarify the respective roles of the real-timecontrol system, the management system, and the network operator, and describe their interactions aimedat managing real-time services. Following thisframework, we introduce an architecture based on theconcept of managing network services by tuning theresource control tasks in the network control system. Todeal with the complexity of the network control system,we present the L-E model, a generic system-levelabstraction of a resource control task. We define high-level controls and visual abstractions forthe network operator which are supported by ourarchitecture. These concepts are evaluated on aprototyping platform, which includes a managementstation implemented on a graphics computer and ahigh-performance parallel machine running in real-timethe control and management systems of a large multimedianetwork. We conclude by describing the results of several experiments that illustrate thequantitative effect of management operations in a largemultimedia network that follows ourarchitecture.     

Synchronization Architecture for Multimedia Services in Mobile Radio Environments

The management of multimedia teleservices inthird-generation mobile radio environments is achallenging task due to the multicomposite andmultirequirement nature of this kind of traffic.Following the choice of carrying multimedia information onmultiple bearers over the air interface of a wirelesspersonal communication system, and after the selectionof a TDMA-like multiple access protocol based on the bandwidth reservation, the system isrequired to provide for an interstream synchronizationamong components of the multimedia service. This paperpresents an architecture for guaranteeing that temporal relationships among components at thetransmitter side can be maintained, after crossing theair interface, at the receiver side, regardless ofdifferent bearers' delay constraints and delays sufferedin the buffer of the base station. The attentionis focused on a kind of roughsynchronization to be performed on the system MAC leveland refined by higher protocol layers. Static anddynamic priorities concepts are exploited to achieve the targetsynchronization degree among components. Simulationresults, carried out in a case of a video-audioconnection, confirm the effectiveness of the proposedmechanism.