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Towards capacity and profit optimization of video-on-demand services in a peer-assisted IPTV platform 总被引:1,自引:0,他引:1
Yih-Farn Chen Yennun Huang Rittwik Jana Hongbo Jiang Michael Rabinovich Jeremy Rahe Bin Wei Zhen Xiao 《Multimedia Systems》2009,15(1):19-32
This paper studies the conditions under which peer-to-peer (P2P) technology may be beneficial in providing IPTV services over
typical network architectures. It has three major contributions. First, we contrast two network models used to study the performance
of such a system: a commonly used logical “Internet as a cloud” model and a “physical” model that reflects the characteristics
of the underlying network. Specifically, we show that the cloud model overlooks important architectural aspects of the network
and may drastically overstate the benefits of P2P technology. Second, we propose an algorithm called Zebra that pre-stripes
content across multiple peers during idle hours to speed up P2P content delivery in an IPTV environment with limited upload
bandwidth. We also perform simulations to measure Zebra’s effectiveness at reducing load on the content server during peak
hours. Third, we provide a cost-benefit analysis of P2P video content delivery, focusing on the profit trade-offs for different
pricing/incentive models rather than purely on capacity maximization. In particular, we find that under high volume of video
demand, a P2P built-in incentive model performs better than any other model, while the conventional no-P2P model generates
more profits when the request rate is low. The flat-reward model generally falls in between the usage-based model and the
built-in model in terms of profitability except for low request rates. We also find that built-in and flat-reward models are
more profitable than the usage-based model for a wide range of subscriber community sizes.
Funding for J. Rahe’s research has been provided by AT&T Labs, the State of California under the MICR Oprogram, and by the
Toshiba Corporation.
Zhen Xiao is partially supported by China MOST project (2006BAH02A10). 相似文献
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Electrochemical passive properties of AlxCoCrFeNi (x = 0, 0.25, 0.50, 1.00) alloys in sulfuric acids
This study investigates the electrochemical passive properties of AlxCoCrFeNi alloys in H2SO4 by potentiodynamic polarization, EIS, and weight loss tests from 20 to 65 °C. Experimental results indicate that Al harms the corrosion resistance in H2SO4 at temperatures exceeding 27 °C owing to the porous and inferior nature of the protection oxide film of Al in these alloys. Closely examining the Arrhenius plots of corrosion current density reveals that both pre-exponential factor A and activation energy Ea increase with Al content. However, A affects corrosion current density more significantly than Ea at higher temperatures and, conversely, at lower temperatures. 相似文献
3.
Chen Yih-Farn Huang Huale Jana Rittwik Jim Trevor Hiltunen Matti John Sam Jora Serban Muthumanickam Radhakrishnan Wei Bin 《Wireless Networks》2003,9(4):283-297
iMobile is an enterprise mobile service platform that allows resource-limited mobile devices to communicate with each other and to securely access corporate contents and services. The original iMobile architecture consists of devlets that provide protocol interfaces to different mobile devices and infolets that access and transcode information based on device profiles. iMobile Enterprise Edition (iMobile EE) is a redesign of the original iMobile architecture to address the security, scalability, and availability requirements of a large enterprise such as AT&T. iMobile EE incorporates gateways that interact with corporate authentication services, replicated iMobile servers with backend connections to corporate services, a reliable message queue that connects iMobile gateways and servers, and a comprehensive service profile database that governs operations of the mobile service platform. The iMobile EE architecture was also extended to provide personalized multimedia services, allowing mobile users to remotely control, record, and request video contents. iMobile EE aims to provide a scalable, secure, and modular software platform that makes enterprise services easily accessible to a growing list of mobile devices roaming among various wireless networks. 相似文献
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Yih-Farn Kao Swe-Kai Chen Jen-Haur Sheu Jiun-Ting Lin Wei-En Lin Jien-Wei Yeh Su-Jien Lin Tzung-Hsien Liou Chia-Wen Wang 《International Journal of Hydrogen Energy》2010
This study presents an innovative multi-principal-element CoFeMnTiVZr alloy system for the absorption and desorption of hydrogen. Pressure-composition-isotherms (PCIs) demonstrate that CoFeMnTixVZr, CoFeMnTiVyZr, and CoFeMnTiVZrz can absorb and desorb hydrogen for x, y, and z that satisfy 0.5 ≤ x ≤ 2.5, 0.4 ≤ y ≤ 3.0, and 0.4 ≤ z ≤ 3.0, respectively. X-ray diffraction (XRD) reveals that CoFeMnTixVyZrz alloys have a simple C14 Laves phase with a single set of lattice parameters before and after PCI tests. The distributions of each element in CoFeMnTixVyZrz alloys are roughly equal, as revealed by SEM/EDS mapping. The effects of values x, y, and z on the hydrogen storage properties are elucidated in terms of lattice constant, element segregation, hydride formation enthalpies of the alloy components and hydrogen, and the averaged formation enthalpy. The high-entropy effect promotes the formation of a single C14 Laves phase, and the maximum hydrogen storage capacity is strongly related to the hydride formation enthalpy of the alloy and hydrogen. 相似文献
5.
Yih-Farn KaoSwe-Kai Chen Ting-Jie ChenPo-Chou Chu Jien-Wei Yeh Su-Jien Lin 《Journal of Alloys and Compounds》2011,509(5):1607-1614
This investigation explores the electrical and magnetic properties of as-cast, -homogenized, and -deformed AlxCoCrFeNi (C-x, H-x, and D-x, respectively) alloys at various temperatures from 4.2 to 300 K. Experimental results reveal that carrier density of the alloys is of 1022-23 cm−3. H-x has a carrier mobility of 0.40-2.61 cm2 V−1 s−1. The residual electrical resistivity of the alloys varies from 100 to 220 μΩ cm. The temperature coefficient of resistivity (TCR) of H-2.00 is small (82.5 ppm/K). Therefore, defects in the lattice dominate electrical transportation. Some compositions exhibit Kondo-like behavior. At 300 K, H-0.50, H-1.25, and H-2.00 are ferromagnetic, while H-0.00, H-0.25, and H-0.75 are paramagnetic. Al and AlNi-rich phases reduce the ferromagnetism of single FCC and single BCC H-x, respectively. Spin glass behavior of some compositions is also observed. Alloys H-x are of the hole-like carrier type, and ferromagnetic H-x exhibits an anomalous Hall effect (AHE). 相似文献
6.
Yih-Farn Robin Chen Rittwik Jana Daniel Stern Bin Wei Mike Yang Hailong Sun Jagadeesh Dyaberi 《Multimedia Systems》2010,16(3):199-214
IPTV, unlike Internet TV, delivers digital TV and multimedia services over IP-based networks with the required level of quality
of service (QoS) and quality of experience (QoE). Linear programming channels in IPTV are delivered through multicast, which
is highly scalable with the number of subscribers. Video-on-demand (VoD) content, on the other hand, is typically delivered
using unicast, which places a heavy load on the VoD servers and all the network components leading to the end-user set-top
boxes (STBs) as the demand increases. With the rapid growth of IPTV subscribers and the shift in video viewing habits, the
need to efficiently disseminate large volumes of VoD content has prompted IPTV service providers to consider the use of STBs
to assist in video content delivery. This paper describes our current research work on Zebroid, a potential VoD solution for
fiber-to-the-node (FTTN) networks, which uses IPTV data on a recurring basis to determine how to select, stripe, and preposition
popular content in selected STBs during idle hours. A STB requesting VoD content during the peak hours can then receive necessary
stripes from participating STBs in the neighborhood. Recent VoD request access patterns, STB availability data, and capacity
data on network components are taken into consideration in determining the parameters used in the striping algorithm of Zebroid.
We show both by simulation and emulation on a realistic IPTV testbed that the VoD server load can be reduced by more than
70% during peak hours by allocating only 8 GB of storage on each STB. The savings achieved through Zebroid would also allow
IPTV service providers to add more linear programming channels without expensive infrastructure upgrades. 相似文献
7.
Buchsbaum A. Yih-Farn Chen Huale Huang Koutsofios E. Mocenigo J. Rogers A. Jankowsky M. Mancoridis S. 《Software, IEEE》2001,18(5):62-70
Companies frequently need to redesign their software infrastructures in response to marketplace changes, but they must do so carefully so that the new architecture will not disrupt existing operations or increase operating costs unnecessarily. To support these goals, system architects have long recognized the need to build a repository of information about all of their company's systems and their interfaces. Using this information, architects create system interface diagrams to help them study the existing architecture. The authors discuss their system, Enterprise Navigator, which lets users make ad hoc queries about an enterprise software architecture and then automatically generate the corresponding system interface diagram in real time on the Web 相似文献
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