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    2013年 第11卷 第1期    刊出日期:2013-03-25
    The whole issue of ZTE Communications March 2013, Vol. 11 No. 1
    2013, 11(1):  0. 
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    Guest Editorial: QoE Modeling and Applications for Multimedia Systems
    Wenjun Zeng and Weisi Lin
    2013, 11(1):  1-1. 
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    Improving the quality and experience perceived by the user is fundamental when developing multimedia technologies, products, and services. Quality of experience (QoE) involves subjective perception, user behavior and needs, appropriateness, context, and usability of delivered content. Modeling QoE is critical for enhancing QoE in various multimedia applications. In this special issue, we present the latest developments, trends, challenges, and practices in QoE modeling and applications for multimedia systems. The seven expert papers in this special issue come from academia and industry. They present some of latest developments in QoE modeling and assessment for emerging scenarios such as 3D video, streaming and cloud systems, user generated content, and mobile user experience.
    We start with two papers that address the problems in 3D QoE assessment and perceptually-driven compression. In“Methodologies for Assessing 3D QoE: Standards and Explorative Studies,”Chen et al. describe the fundamentals of existing subjective video quality assessment methods that are the starting point for 3DTV QoE assessment. The authors discuss potential methods for assessing QoE in stereoscopic 3DTV, focusing mainly on multidimensional QoE indicators and common features of subjective assessment. In“3D Perception Algorithms: Towards Perceptually Driven Compression of 3D Video,”Hu et al. highlight the differences in perceptual effects between 2D and 3D video. They then share their ideas about 3D video coding and transmission, taking into consideration 3D visual attention, 3D just-noticeable-difference, and 3D texture synthesis modeling. We hope that these two papers prompt further thinking about emerging 3D signal processing.
    QoE estimation and modeling has been an important tool for improving user experience in multimedia communication systems. In“Estimating Reduced-Reference Video Quality for Quality-Based Streaming Video,”Atzori et al. analyze reduced-reference algorithms for modeling signal distortion, modeling the human visual system, and analyzing the video signal source. The authors then discuss the practical use of these reduced-reference techniques for monitoring and controlling quality in streaming video systems. As the mobile cloud computing paradigm emerges, QoE has become a much more important issue to investigate. In“Human-Centric Composite-Quality Modeling and Assessment for Virtual Desktop Clouds,”Xu et al. propose a novel reference architecture and discuss its use in modeling and assessing objective user QoE within virtual desktop clouds. This architecture avoids the need for expensive and time-consuming subjective evaluation.
    With the widespread use of smartphones, digital cameras, imaging software, photo-sharing sites, and social networks, the amount of user-generated content has grown tremendously. In “Assessing the Quality of User-Generated Content,”Winkler compares the traditional approaches to assessing quality of user-generated content with new approaches. Some sample applications are also discussed. In“An Improved Color Cast Detection Method Based on Ab-Chromaticity Histogram,”Lu et al. propose a new method for evaluating the quality of an image in order to improve color cast detection. This is a necessary step before further image processing, such as white balance, is applied.
    Energy consumption is a big issue for mobile devices and services. In“Battery Voltage Discharge Rate Prediction and Video Content Adaptation in Mobile Devices on 3G Access Networks,”Mkwawa and Sun propose a way of performing visual content adaptation that saves energy. A regression model is used to predict the battery voltage discharge rate in VoIP applications. This is an interesting attempt. Optimizing user experience with a limited battery is challenging for practical system design (starting from algorithm development).
    The guest editorial team would like to thank all authors for submitting their high-quality work to this special issue. We would also like to thank the reviewers whose hard work and expert contributions have ensured the quality of this issue. We hope you enjoy reading these fine quality papers.
    Methodologies for Assessing 3D QoE: Standards and Explorative Studies
    Wei Chen, Jérôme Fournier, Marcus Barkowsky, and Patrick Le Callet
    2013, 11(1):  2-10. 
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    Mastering quality of experience (QoE) is key to the widespread adoption of stereoscopic 3DTV (S-3DTV). However, assessing QoE of S-3DTV is not straightforward. Methods for determining observer experience need to be clearly defined and sufficiently robust. In this paper, we present state-of-the-art subjective QoE assessment for S-3DTV. We present conventional standardized ITU recommendations for evaluating picture quality and discuss new ITU activities in the area of S-3DTV assessment. We also present and discuss explorative studies from the literature. We then introduce ways of using conventional quality assessment for S-3DTV QoE assessment. In discussing our proposal, we mainly focus on QoE indicators and common features of subjective assessment. Multidimensional QoE indicators need to be used in S-3DTV to highlight advantages and reveal problems. In the second part of our proposal, we discuss the requirements for adapting ITU-R BT.500, a conventional subjective QoE assessment method, ITU-R BT.500, for assessing QoE of S-3DTV are presented.
    3D Perception Algorithms: Towards Perceptually Driven Compression of 3D Video
    Ruimin Hu, Rui Zhong, Zhongyuan Wang, and Zhen Han
    2013, 11(1):  11-16. 
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    In this paper, we summarize 3D perception-oriented algorithms for perceptually driven 3D video coding. Several perceptual effects have been exploited for 2D video viewing; however, this is not yet the case for 3D video viewing. 3D video requires depth perception, which implies binocular effects such as con fl icts, fusion, and rivalry. A better understanding of these effects is necessary for 3D perceptual compression, which provides users with a more comfortable visual experience for video that is delivered over a channel with limited bandwidth. We present state-of-the-art of 3D visual attention models, 3D just-noticeable difference models, and 3D texture-synthesis models that address 3D human vision issues in 3D video coding and transmission.
    Estimating Reduced-Reference Video Quality for Quality-Based Streaming Video
    Luigi Atzori, Alessandro Floris, Giaime Ginesu, and Daniele D. Giusto
    2013, 11(1):  17-26. 
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    Reduced-reference (RR) video-quality estimators send a small signature to the receiver. This signature comprises the original video content as well as the video stream. RR quality estimation provides reliability and involves a small data payload. While significant in theory, RR estimators have only recently been used in practice for quality monitoring and adaptive system control in streaming-video frameworks. In this paper, we classify RR algorithms according to whether they are based on a) modeling the signal distortion, b) modeling the human visual system, or c) analyzing the video signal source. We review proposed RR techniques for monitoring and controlling quality in streaming video systems.
    Human-Centric Composite-Quality Modeling and Assessment for Virtual Desktop Clouds
    Yingxiao Xu, Prasad Calyam, David Welling, Saravanan Mohan, Alex Berryman, and Rajiv Ramnath
    2013, 11(1):  27-36. 
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    There are several motivations, such as mobility, cost, and security, that are behind the trend of traditional desktop users transitioning to thin-client-based virtual desktop clouds (VDCs). Such a trend has led to the rising importance of human-centric performance modeling and assessment within user communities that are increasingly making use of desktop virtualization. In this paper, we present a novel reference architecture and its easily deployable implementation for modeling and assessing objective user quality of experience (QoE) in VDCs. This architecture eliminates the need for expensive, time-consuming subjective testing and incorporates finite-state machine representations for user workload generation. It also incorporates slow-motion benchmarking with deep-packet inspection of application task performance affected by QoS variations. In this way, a “composite-quality”metric model of user QoE can be derived. We show how this metric can be customized to a particular user group profile with different application sets and can be used to a) identify dominant performance indicators and troubleshoot bottlenecks and b) obtain both absolute and relative objective user QoE measurements needed for pertinent selection of thin-client encoding configurations in VDCs. We validate our composite-quality modeling and assessment methodology by using subjective and objective user QoE measurements in a real-world VDC called VDPilot, which uses RDP and PCoIP thin-client protocols. In our case study, actual users are present in virtual classrooms within a regional federated university system.
    Assessing the Quality of User-Generated Content
    Stefan Winkler
    2013, 11(1):  37-40. 
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    With the widespread use of digital cameras, imaging software, photo-sharing sites, social networks, and other related technologies, media production and consumption patterns have become much more multifaceted and complex than they used to be. User-generated content in particular has grown tremendously. As a result, quality of experience (QoE) and related quality assessment (QA) methods must also be looked at from a different angle. This paper contrasts some of the traditional quality assessment approaches with newer approaches designed for user-generated content. It also describes some sample applications we have developed.
    An Improved Color Cast Detection Method Based on an AB-Chromaticity Histogram
    Ping Lu, Xia Jia, and Tirui Wu
    2013, 11(1):  41-43. 
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    AB-chromaticity histogram analysis works well most of the time, but it may not work well when the color cast is not severe. To overcome this problem, we propose an improved, two-step automatic cast-detection method. First, we compute the RGB color variance to evaluate the quality of the input image. If this variance is very small, we extract near-neutral color areas and compute the local ab-chromaticity histogram. We use this local ab-chromaticity histogram to evaluate the quality of the input image. This method has been tested in ZTE’s video surveillance system. The results show that the proposed method produces better results based on subjective evaluation and is more efficient in various conditions.
    Battery Voltage Discharge Rate Prediction and Video Content Adaptation in Mobile Devices on 3G Access Networks
    Is-Haka Mkwawa and Lingfen Sun
    2013, 11(1):  44-50. 
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    According to Cisco, mobile multimedia services now account for more than half the total amount of Internet traffic. This trend is burdening mobile devices in terms of power consumption, and as a result, more effort is needed to devise a range of power-saving techniques. While most power-saving techniques are based on sleep scheduling of network interfaces, little has been done to devise multimedia content adaptation techniques. In this paper, we propose a multiple linear regression model that predicts the battery voltage discharge rate for several video send bit rates in a VoIP application. The battery voltage discharge rate needs to be accurately estimated in order to estimate battery life in critical VoIP contexts, such as emergency communication. In our proposed model, the range of video send bitrates is carefully chosen in order to maintain an acceptable VoIP quality of experience. From extensive profiling, the empirical results show that the model effectively saves power and prolongs real-time VoIP sessions when deployed in power-driven adaptation schemes.
    FBAR-Based Radio Frequency Bandpass Filter for 3G TD-SCDMA
    Mingke Qi, Liangzhen Du, and Hao Zhang
    2013, 11(1):  51-53. 
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    In this paper, we describe a high-performance TD-SCDMA bandpass filter based on film bulk acoustic resonator (FBAR) technology. The filter comprises a group of FBARs connected in a ladder configuration. Excellent quality factor greater than 1000 has been achieved at resonant frequency near 2 GHz for the FBAR. The TD-SCDMA FBAR filter has been fabricated and tested. The filter has low passband insertion loss of 1.7 dB and high stop-band rejection greater than 35 dB.
    Data Center Network Architecture
    Yantao Sun, Jing Cheng, Konggui Shi, and Qiang Liu
    2013, 11(1):  54-61. 
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    The rapid development of cloud computing has created significant challenges in data center architecture. In this paper, we discuss these challenges. We introduce the latest research on data center network architecture, especially in terms of structure and virtual machine migration. We also introduce research in areas related to network architecture. Finally, we suggest future research areas in data center networks.
    Android Apps: Static Analysis Based on Permission Classification
    Zhenjiang Dong, Hui Ye, Yan Wu, Shaoyin Cheng, and Fan Jiang
    2013, 11(1):  62-66. 
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    Android has a strict permission management mechanism. Any applications that try to run on the Android system need to obtain permission. In this paper, we propose an efficient method of detecting malicious applications in the Android system. First, hundreds of permissions are classified into different groups. The application programming interfaces (APIs) associated with permissions that can interact with the outside environment are called sink functions. The APIs associated with other permissions are called taint functions. e construct association tables for block variables and function variables of each application. Malicious applications can then be detected by using the static taint-propagation method to analyze these tables.