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Wireless Communications, IEEE

Issue 4 • Date Aug. 2005

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Displaying Results 1 - 12 of 12
  • Error resilience video transcoding for wireless communications

    Publication Year: 2005 , Page(s): 14 - 21
    Cited by:  Papers (27)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB) |  | HTML iconHTML  

    Video communication through wireless channels is still a challenging problem due to the limitations in bandwidth and the presence of channel errors. Since many video sources are originally coded at a high rate and without considering the different channel conditions that may be encountered later, a means to repurpose this content for delivery over a dynamic wireless channel is needed. Transcoding is typically used to reduce the rate and change the format of the originally encoded video source to match network conditions and terminal capabilities. Given the existence of channel errors that can easily corrupt video quality, there is also the need to make the bitstream more resilient to transmission errors. In this article we provide an overview of the error resilience tools found in today's video coding standards and describe a variety of techniques that may be used to achieve error-resilient video transcoding. View full abstract»

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  • Rate control for streaming video over wireless

    Publication Year: 2005 , Page(s): 32 - 41
    Cited by:  Papers (27)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB) |  | HTML iconHTML  

    Rate control is an important issue in video streaming applications for both wired and wireless networks. A widely accepted rate control method in wired networks is TCP-friendly rate control (TFRC) (Floyd, 2000). It is equation-based rate control in which the TCP-friendly rate is determined as a function of packet loss rate, round-trip time, and packet size. TFRC assumes that packet loss in wired networks is primarily due to congestion, and as such is not applicable to wireless networks in which the main cause of packet loss is at the physical layer. In this article we review existing approaches to solve this problem. Then we propose multiple TFRC connections as an end-to-end rate control solution for wireless video streaming. We show that this approach not only avoids modifications to the network infrastructure or network protocol, but also results in full utilization of the wireless channel. NS-2 simulations, actual experiments over a 1×RTT CDMA wireless data network, and video streaming simulations using traces from the actual experiments are carried out to characterize the performance and show the efficiency of our proposed approach. View full abstract»

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  • Cross-layer wireless multimedia transmission: challenges, principles, and new paradigms

    Publication Year: 2005 , Page(s): 50 - 58
    Cited by:  Papers (206)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB) |  | HTML iconHTML  

    Wireless networks are poised to enable a variety of existing and emerging multimedia streaming applications. As the use of wireless local area networks spreads beyond simple data transfer to bandwidth-intense, delay-sensitive, and loss-tolerant multimedia applications, addressing quality of service issues become extremely important. Currently, a multitude of protection and adaptation strategies exists in the different layers of the open systems interconnection (OSI) stack. Hence, an in-depth understanding and comparative evaluation of these strategies are necessary to effectively assess and enable the possible trade-offs in multimedia quality, power consumption, implementation complexity, and spectrum utilization that are provided by the various OSI layers. This further opens the question of cross-layer optimization and its effectiveness in providing an improved solution with respect to the above trade-offs. In this article we formalize the cross-layer problem, discuss its challenges, and present several possible solutions. Moreover, we also discuss the impact the cross-layer optimization strategy deployed at one station has on the multimedia performance of other stations. We introduce a new fairness concept for wireless multimedia systems that employs different cross-layer strategies, and show its advantages when compared to existing resource allocation mechanisms used in wireline communications. Finally, we propose a new paradigm for wireless communications based on competition, which allows wireless stations to harvest additional resources or free up resources as well as optimally and dynamically adapt their cross-layer transmission strategies to improve multimedia quality and/or power consumption. View full abstract»

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  • Energy-efficient wireless video coding and delivery

    Publication Year: 2005 , Page(s): 24 - 30
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (315 KB) |  | HTML iconHTML  

    Transmitting video over wireless channels from mobile devices has gained increased popularity in a wide range of applications. A major obstacle in these types of applications is the limited energy supply in mobile device batteries. For this reason, efficiently utilizing energy is a critical issue in designing wireless video communication systems. This article highlights recent advances in joint source coding and optimal energy allocation. We present a general framework that takes into account multiple factors, including source coding, channel resource allocation, and error concealment, for the design of energy-efficient wireless video communication systems. This framework can take various forms and be applied to achieve the optimal trade-off between energy consumption and video delivery quality during wireless video transmission. View full abstract»

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  • Cross-layer design of ad hoc networks for real-time video streaming

    Publication Year: 2005 , Page(s): 59 - 65
    Cited by:  Papers (107)  |  Patents (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (171 KB) |  | HTML iconHTML  

    Cross-layer design breaks away from traditional network design where each layer of the protocol stack operates independently. We explore the potential synergies of exchanging information between different layers to support real-time video streaming. In this new approach information is exchanged between different layers of the protocol stack, and end-to-end performance is optimized by adapting to this information at each protocol layer. We discuss key parameters used in the cross-layer information exchange along with the associated cross-layer adaptation. Substantial performance gains through this cross-layer design are demonstrated for video streaming. View full abstract»

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  • H.264/AVC video for wireless transmission

    Publication Year: 2005 , Page(s): 6 - 13
    Cited by:  Papers (47)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (159 KB) |  | HTML iconHTML  

    H.264/AVC will be an essential component in emerging wireless video applications thanks to its excellent compression efficiency and network-friendly design. However, a video coding standard itself is only one component within the application and transmission environment. Its effectiveness strongly depends on the selection of appropriate modes and parameters at the encoder, at the decoder, as well as in the network. In this paper we introduce the features of the H.264/AVC coding standard that make it suitable for wireless video applications, including features for error resilience, bit rate adaptation, integration into packet networks, interoperability, and buffering considerations. Modern wireless networks provide many different means to adapt quality of service, such as forward error correction methods on different layers and end-to-end or link layer retransmission protocols. The applicability of all these encoding and network features depends on application constraints, such as the maximum tolerable delay, the possibility of online encoding, and the availability of feedback and cross-layer information. We discuss the use of different coding and transport related features for different applications, namely video telephony, video conferencing, video streaming, download-and-play, and video broadcasting. Guidelines for the selection of appropriate video coding tools, video encoder and decoder settings, as well as transport and network parameters are provided and justified. References to relevant research publications and standardization contributions are given. View full abstract»

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  • Advances in wireless video

    Publication Year: 2005 , Page(s): 4 - 5
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (478 KB) |  | HTML iconHTML  

    First Page of the Article
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  • Multipath video transport over ad hoc networks

    Publication Year: 2005 , Page(s): 42 - 49
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (154 KB) |  | HTML iconHTML  

    Real-time multimedia transport has stringent bandwidth, delay, and loss requirements. It is a great challenge to support such applications in wireless ad hoc networks, which are characterized by frequent link failures and congestion. Using multiple paths in parallel for a real-time multimedia session (called multipath transport) provides a new degree of freedom in designing robust multimedia transport systems. In this article, we describe a framework for multipath video transport over wireless ad hoc networks, and examine its essential components, including multistream video coding, multipath routing, and transport mechanisms. We illustrate by three representative examples how to extend existing video coding schemes in order to fully explore the potential of multipath transport. We also examine important mechanisms in different layers for supporting multipath video transport over ad hoc networks. Our experiments show that multipath transport is a promising technique for efficient video communications over ad hoc networks. View full abstract»

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  • IEEE Wireless Communications Aug. 2005 - Vol. 12 No. 4

    Publication Year: 2005 , Page(s): 0_1
    Save to Project icon | Request Permissions | PDF file iconPDF (940 KB)  
    Freely Available from IEEE
  • IEEE Wireless Communications Magazine - Table of contents

    Publication Year: 2005 , Page(s): 1
    Save to Project icon | Request Permissions | PDF file iconPDF (71 KB)  
    Freely Available from IEEE
  • The Challenge of Delivering Wireless Video - Message from the editor-in-chief

    Publication Year: 2005 , Page(s): 2
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    Freely Available from IEEE
  • Wireless video applications in 3G and beyond

    Publication Year: 2005 , Page(s): 66 - 72
    Cited by:  Papers (15)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    This article surveys wireless video applications that have been commercialized recently or are expected to go to market in 3G (and beyond) mobile networks, mainly covering error control technologies in view of "wireless video." We introduce several related 3GPP standards including circuit-switched multimedia telephony, end-to-end packet-switched streaming, multimedia messaging service, and multimedia broadcast /multimedia service. We also review the supporting technologies for those four applications. The article concludes with a discussion of error control and rate control adaptability to network QoS variation, which is distinct from wired networks and critical to wireless networks. With respect to MBMS, we point out that required cell transmission power is crucial when realizing meaningful multicast coverage, and suggest a system that integrates different unicast and multicast networks, application-layer data repair, and transmission scheduling. View full abstract»

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Aims & Scope

IEEE Wireless Communications Magazine deals with all technical and policy issues related to personalization, location-independent communications in all media.

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Meet Our Editors

Editor-in-Chief
Hsiao-Hwa Chen
Cheng Kung University, Taiwan