Ad hoc networks play important roles in next generation mobile systems. They have not any wired infrastructure support. In ad hoc networks, nodes change their position frequently and each node can act as a router. Due...
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Ad hoc networks play important roles in next generation mobile systems. They have not any wired infrastructure support. In ad hoc networks, nodes change their position frequently and each node can act as a router. Due to high mobility and frequently links breakage, selecting the reliable path is a critical challenge. multimedia applications need robust path as a key issue for achieving higher performance. In this paper, we propose a new metric to add to the routing table to achieve this. By exploiting the routing table stability parameter (RTSP) in each node, we can predict fragile routes and thus provide a mechanism to select robust path to increase efficiency. Each node computes RTSP in a distribution mechanism and adds this metric to route request and reply packets. We use Global Mobile Simulation (GloMoSim) environment to simulate our method. Routing in mobile ad hoc networks (MANET) with considering RTSP factor improves packet delivery ratio. Simulation results also demonstrate that adding RTSP factor to routing table improves throughput and but slightly increases end-to-end delay with increasing mobility.
We describe the architecture and implementation of our comprehensive multi-platform collaboration framework known as Columbia InterNet Extensible multimedia Architecture (CINEMA). It provides a distributed architectur...
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ISBN:
(纸本)0819452084
We describe the architecture and implementation of our comprehensive multi-platform collaboration framework known as Columbia InterNet Extensible multimedia Architecture (CINEMA). It provides a distributed architecture for collaboration using synchronous communications like multimedia conferencing, instant messaging, shared web-browsing, and asynchronous communications like discussion forums, shared files, voice and video mails. It allows seamless integration with various communication means like telephones, IP phones, web and electronic mail. In addition, it provides value-added services such as call handling based on location information and presence status. The paper discusses the media services needed for collaborative environment, the components provided by CINEMA and the interaction among those components.
In wireless multimedia applications, low bitrate video takes an important part. However, its poor subjective quality often dissatisfies consumers. In this paper, we present a mixed scheme to improve subjective quality...
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ISBN:
(纸本)0780383443
In wireless multimedia applications, low bitrate video takes an important part. However, its poor subjective quality often dissatisfies consumers. In this paper, we present a mixed scheme to improve subjective quality in low bitrate video. Our scheme is a combination of several original techniques: fast dynamic key-frame / variable frame-rate coding, ringing effect reduction, band effect reduction, and resolution / quantization tradeoff. The scheme can be applied on many popular video-coding standards, such as MPEG-1, MPEG-2, MPEG-4, and H.264. Additional computing costs involved by the scheme are acceptable. Experiments show significant improvement of subjective quality, and prove that the scheme is valuable.
As video conferencing and e-meeting systems are used more and more on the Internet and in businesses it becomes increasingly important to be able to participate from any computer at any location. Often this is impossi...
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ISBN:
(纸本)0819452084
As video conferencing and e-meeting systems are used more and more on the Internet and in businesses it becomes increasingly important to be able to participate from any computer at any location. Often this is impossible, since these systems requires often special software that are not available everywhere or impossible to install for administrative reasons. Many locations also lack the necessary network infrastructure such as IP multicast. This paper presents a WWW gateway System that enables users to participate using only a standard web browser The design and architecture of the system are described and performance tests that show the scalability of the system are also presented.
Advances in wireless communication and mobile computing and networking are providing us with growing business opportunities and demands for multimedia services. Consumer networks, increasingly used for multimedia info...
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ISBN:
(纸本)0780385330
Advances in wireless communication and mobile computing and networking are providing us with growing business opportunities and demands for multimedia services. Consumer networks, increasingly used for multimedia information and commercial content delivery, are destined to be heterogeneous. Meanwhile, for many multimedia services, security is an important component to restrict unauthorized content access and distribution. This suggests the need for new cryptography system implementations that can operate at different data rates, i.e., be scaled to various multimedia content, different network topology, changing bandwidth, and diverse device capabilities. Encryption is used to ensure confidentiality of messages in communication. Conventional encryption schemes do not offer suitable scalability for this new set of applications. In this paper, we describe scalable encryption, discuss the applications for consumer multimedia access, present scalable encryption schemes that support various kinds of scalability, and present a scalable content access scheme using an algebraic based differentiable-decryption key public key crypto algorithm.
The proceedings contain 18 papers from the conference on SPIE: multimediacomputing and networking 2004. The topics discussed include: movie placement in a hierarchical CDN with stream merging mechanism;congestion con...
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The proceedings contain 18 papers from the conference on SPIE: multimediacomputing and networking 2004. The topics discussed include: movie placement in a hierarchical CDN with stream merging mechanism;congestion control and maessage loss in Gnutella networks;energy conservation in ad hoc multimedia networks using traffic-shaping mechanisms;process group management in cross-layer adaptation and performance analysis of a hybrid media streaming system.
In this work, we explore network traffic shaping mechanisms that deliver packets at pre-determined intervals;allowing the network interface to transition to a lower power consuming sleep state. We focus our efforts on...
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ISBN:
(纸本)0819452084
In this work, we explore network traffic shaping mechanisms that deliver packets at pre-determined intervals;allowing the network interface to transition to a lower power consuming sleep state. We focus our efforts on commodity devices, IEEE 802.11b ad hoc mode and popular streaming formats. We argue that factors such as the lack of scheduling clock phase synchronization among the participants and scheduling delays introduced by back ground tasks affect the potential energy savings. Increasing the periodic transmission delays to transmit data infrequently can offset some of these effects at the expense of flooding the wireless channel for longer periods of time;potentially increasing the time to acquire the channel for non-multimedia traffic. Buffering mechanisms built into media browsers can mitigate the effects of these added delays from being mis-interpreted as network congestion. We show that practical implementations of such traffic shaping mechanisms can offer significant energy savings.
Peer-to-peer system performance is dependent on the routing efficiency of the underlying overlay network. Overlay congestion, which may occur during the forwarding process on peers, can have an adverse impact on the p...
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ISBN:
(纸本)0819452084
Peer-to-peer system performance is dependent on the routing efficiency of the underlying overlay network. Overlay congestion, which may occur during the forwarding process on peers, can have an adverse impact on the performance of an overlay network. Although previous work has been aware of its existence and taken measures against it, the study of overlay congestion has received little attention. As a result, little is known about its system performance impact and how well it is handled currently. In this work, we initiate an investigation of congestion control and message loss in a specific peer-to-peer system-the Gnutella network. Our work starts with an analysis of Gnutella servent implementations. This reveals the heterogeneity among their implementations of congestion control. We next undertake a measurement study to characterize the message loss behavior in a Gnutella network and how it relates to the congestion control mechanisms implemented by the servents. We then use packet-level simulations to understand the global performance of certain Gnutella congestion control mechanisms.
In recent literature a powerful multiple description product coding scheme for protection of progressively encoded source streams has been devised that. disperses information evenly between all description packets, Al...
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ISBN:
(纸本)0780383443
In recent literature a powerful multiple description product coding scheme for protection of progressively encoded source streams has been devised that. disperses information evenly between all description packets, Also, techniques were proposed to protect these packets equally by an optimal channel coder (found by exhaustive search). The contribution of this paper is to show that. equal protection of all descriptions is suboptimal when the channel varies with time despite the fact that all descriptions have equal importance. We propose a theoretical framework for computing the globally optimal channel protection assignment for a given set of available channel coders under some idealized assumptions. For more practical scenarios we propose an optimized uneven packet protection scheme that outperforms equal protection schemes in terms of the expected distortion of received sources. Simulations of an image transmission system that resembles a 3G high bitrate link is provided where our unequal protection scheme. improves the average PSNR. of the received images by more than 1.3dB.
The latest achievements in the field of mobile networks and ubiquitous computing enable the integration and combination of technologies like Internet, Java, and multimedia in a new kind of application that employs dis...
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ISBN:
(纸本)1581138938
The latest achievements in the field of mobile networks and ubiquitous computing enable the integration and combination of technologies like Internet, Java, and multimedia in a new kind of application that employs distribution, wireless networking, localisation, and movement - mobile location-aware multimedia games. The approach presented is an innovative re-invention of a paper chase/scavenger hunt as a mobile location-aware game. The video demonstration illustrates the technical foundation and the system design of the mobile game. We also show the fun and the action of the game following some students when they play the game on our university campus.
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