Int. J. Digit. Multim. Broadcast.最新文献

{"title":"Adjustable Two-Tier Cache for IPTV Based on Segmented Streaming","authors":"Liang Kai-Chun, Hsiang-Fu Yu","doi":"10.1155/2012/192314","DOIUrl":"https://doi.org/10.1155/2012/192314","url":null,"abstract":"Internet protocol TV (IPTV) is a promising Internet killer application, which integrates video, voice, and data onto a single IP network, and offers viewers an innovative set of choices and control over their TV content. To provide high-quality IPTV services, an effective strategy is based on caching. This work proposes a segment-based two-tier caching approach, which divides each video into multiple segments to be cached. This approach also partitions the cache space into two layers, where the first layer mainly caches to-be-played segments and the second layer saves possibly played segments. As the segment access becomes frequent, the proposed approach enlarges the first layer and reduces the second layer, and vice versa. Because requested segments may not be accessed frequently, this work further designs an admission control mechanism to determine whether an incoming segment should be cached or not. The cache architecture takes forward/stop playback into account and may replace the unused segments under the interrupted playback. Finally, we conduct comprehensive simulation experiments to evaluate the performance of the proposed approach. The results show that our approach can yield higher hit ratio than previous work under various environmental parameters.","PeriodicalId":204253,"journal":{"name":"Int. J. Digit. Multim. Broadcast.","volume":"2012 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128729262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monitoring Accessibility Services in Digital Television","authors":"Francisco Utray, Mercedes de Castro, Lourdes Moreno, B. Ruíz-Mezcua","doi":"10.1155/2012/294219","DOIUrl":"https://doi.org/10.1155/2012/294219","url":null,"abstract":"This paper addresses methodology and tools applied to the monitoring of accessibility services in digital television at a time when the principles of accessibility and design are being considered in all new audiovisual media communication services. The main objective of this research is to measure the quality and quantity of existing accessibility services offered by digital terrestrial television (DTT). The preliminary results, presented here, offer the development of a prototype for automatic monitoring and a methodology for obtaining quality measurements, along with the conclusions drawn by initial studies carried out in Spain. The recent approval of the UN Convention on the Rights of Persons with Disabilities gives special relevance to this research because it provides valuable guidelines to help set the priorities to improve services currently available to users.","PeriodicalId":204253,"journal":{"name":"Int. J. Digit. Multim. Broadcast.","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115331405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Seamless Broadcasting Scheme with Live Video Support","authors":"Zeng-Yuan Yang, Yi-Ming Chen, L. Tseng","doi":"10.1155/2012/373459","DOIUrl":"https://doi.org/10.1155/2012/373459","url":null,"abstract":"Broadcasting schemes, such as the fast broadcasting and harmonic broadcasting schemes, significantly reduce the bandwidth requirement of video-on-demand services. In the real world, some history events are very hot. For example, every year in March, thousands of people connect to Internet to watch the live show of Oscar Night. Such actions easily cause the networks contested. However, the schemes mentioned previously cannot alleviate the problem because they do not support live broadcasting. In this paper, we analyze the requirements for transferring live videos. Based on the requirements, a time skewing approach is proposed to enable the broadcasting schemes to support live broadcasting. However, the improved schemes require extra bandwidth for live broadcasting once the length of live shows exceeds the default. Accordingly, we proposed a scalable binomial broadcasting scheme to transfer live videos using constant bandwidth by increasing clients’ waiting time. When the scheme finds that the length of a video exceeds the default, it doubles the length of to-be-played segments and then its required bandwidth is constant.","PeriodicalId":204253,"journal":{"name":"Int. J. Digit. Multim. Broadcast.","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115289851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Efficient Periodic Broadcasting with Small Latency and Buffer Demand for Near Video on Demand","authors":"Ying-Nan Chen, L. Tseng","doi":"10.1155/2012/717538","DOIUrl":"https://doi.org/10.1155/2012/717538","url":null,"abstract":"Broadcasting Protocols can efficiently transmit videos that simultaneously shared by clients with partitioning the videos into segments. Many studies focus on decreasing clients' waiting time, such as the fixed-delay pagoda broadcasting (FDPB) and the harmonic broadcasting schemes. However, limited-capability client devices such as PDAs and set-top boxes (STBs) suffer from storing a significant fraction of each video while it is being watched. How to reduce clients' buffer demands is thus an important issue. Related works include the staircase broadcasting (SB), the reverse fast broadcasting (RFB), and the hybrid broadcasting (HyB) schemes. This work improves FDPB to save client buffering space as well as waiting time. In comparison with SB, RFB, and HyB, the improved FDPB scheme can yield the smallest waiting time under the same buffer requirements.","PeriodicalId":204253,"journal":{"name":"Int. J. Digit. Multim. Broadcast.","volume":"2012 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128910577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficient Wireless Broadcasting through Joint Network Coding and Beamforming","authors":"Monchai Lertsutthiwong, Thinh P. Q. Nguyen, B. Hamdaoui","doi":"10.1155/2012/342512","DOIUrl":"https://doi.org/10.1155/2012/342512","url":null,"abstract":"We develop a framework that exploits network coding (NC) and multiple-input/multiple-output (MIMO) techniques, jointly together, to improve throughput of downlink broadcast channels. Specifically, we consider a base station (BS) equipped with multiple transmit antennas that serves multiple mobile stations (MSs) simultaneously by generating multiple signal beams. Given the large number of MSs and the small number of transmit antennas, the BS must decide, at any transmission opportunity, which group of MSs it should transmit packets to, in order to maximize the overall throughput. We propose two algorithms for grouping MSs that take advantage of NC and the orthogonality of user channels to improve the overall throughput. Our results indicate that the proposed techniques increase the achievable throughput significantly, especially in highly lossy environments.","PeriodicalId":204253,"journal":{"name":"Int. J. Digit. Multim. Broadcast.","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127696304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LDPC FEC Code Extension for Unequal Error Protection in DVB-T2 System: Design and Evaluation","authors":"L. Kondrad, Imed Bouazizi, M. Gabbouj","doi":"10.1155/2012/834924","DOIUrl":"https://doi.org/10.1155/2012/834924","url":null,"abstract":"The Digital Video Broadcasting organisation has recently introduced the second generation of terrestrial broadcast transmission standards, DVB-T2. The newly introduced tools ensure significant gain in performance of DVB-T2 compared to the first generation variant of the standard. One of these tools is the new physical layer concatenated forward error correction code. The inner among the concatenated codes is the Low-Density Parity Check code. The paper proposes a method to extend this code so varying coding strength inside one physical layer pipe of DVB-T2 is enabled in a backward compatible way. As consequence, unequal error protection transmission scheme at a physical layer of DVB-T2 can be efficiently deployed. The paper provides a step-by-step description of the design procedure of the extension. Moreover, the modification to the processing chain and the framing structure of DVB-T2, that ensures backward compatibility to the legacy system, is provided. The proposed method is evaluated under AWGN channel and TU6 channel. Experiments performed on four different video sequences show significant improvements in quality of experience when the proposed extension is used to achieve UEP transmission.","PeriodicalId":204253,"journal":{"name":"Int. J. Digit. Multim. Broadcast.","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115922733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Low-Complexity Resource Allocation Algorithm for MIMO-OFDMA Multicast Systems with Spectrum-Guarantee Provisioning","authors":"I. Fraimis, S. Kotsopoulos","doi":"10.1155/2012/585267","DOIUrl":"https://doi.org/10.1155/2012/585267","url":null,"abstract":"We study the important problem of resource allocation for the downlink of Multiple-Input Multiple output (MIMO) Multicast Wireless Systems operating over frequency-selective channels and we propose a low-complexity but efficient resource allocation algorithm for MIMO-enabled OFDMA systems. The proposed solution guarantees a minimum spectrum share for each user while also takes advantage of the multicast transmission mode. The presence of multiple antennas in both transmitter and receiver offers spatial diversity to the system along with the frequency diversity added by the OFDMA access scheme. The computational complexity is reduced from exponential to linear and validation of the proposed solution is achieved through various simulation scenarios in comparison with other multicast and unicast reference schemes used in MIMO-OFDMA systems. Numerical results and complexity analysis demonstrate the feasibility of the proposed algorithm.","PeriodicalId":204253,"journal":{"name":"Int. J. Digit. Multim. Broadcast.","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117329278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cloud Computing and Dynamic Resource Allocation for Multimedia Applications","authors":"Yifeng He, L. Guan, Wenwu Zhu, I. Lee","doi":"10.1155/2012/238460","DOIUrl":"https://doi.org/10.1155/2012/238460","url":null,"abstract":"We have witnessed significant advances in multimedia applications due to the rapid increase in digital media, computing power, communication speed, and storage capacity. Multi-media has become an indispensable aspect in contemporary daily life. Recently, cloud computing technology has offered great opportunities for multimedia applications. The performance of the multimedia applications can be significantly improved by optimizing the various resources in the mul-timedia system. The papers selected for this special issue represent a good panel for addressing the resource allocation problems in multimedia applications. We would like to thank the authors for their excellent contributions. We are grateful to all reviewers for their constructive comments which help to improve the quality of the papers. This special issue contains five papers, in which two papers are related to cloud-based multimedia applications, two papers deal with Peer-to-Peer (P2P) video streaming systems, and one paper addresses the resource allocation problem in wireless networks. In the paper entitled \" Multi-objective genetic algorithm for task assignment on heterogeneous nodes, \" C. B. P. Del Notario et al. present a task assignment strategy based on genetic algorithms for a client-cloud multimedia system. Specifically, the task execution quality is maximized under the constraints of energy and bandwidth. In the video processing scenario, the proposed method employs trans-coding to provide a tradeoff between video quality and processing and band-width demands. In the paper entitled \" Towards an automatic parameter-tuning framework for cost optimization on video encoding cloud, \" X. Li et al. conduct an empirical study on video encoding cloud, targeting an optimization framework to minimize H.264 encoding cost by tuning the key parameters. The experiment results show that the tested parameters can be independently tuned to minimize the encoding cost, which makes the automatic parameter-tuning framework feasible and promising for video encoding cloud. In the paper entitled \" Improving streaming capacity in multi-channel P2P VoD systems via intra-channel and cross-channel resource allocation, \" Y. He and L. Guan. present novel methods to improve the streaming capacity for a multi-channel P2P video-on-demand (VoD) system by efficiently utilizing both intrachannel and cross-channel resources. The intrachannel resource allocation problem can be formulated into a linear programming (LP) problem. The cross-channel resource allocation can be enabled by both optimal server upload allocation among channels and cross-channel sharing of peer upload bandwidths. In the paper entitled \" Performance evaluation of an object management policy approach for P2P networks, \" D. Vieira et al. …","PeriodicalId":204253,"journal":{"name":"Int. J. Digit. Multim. Broadcast.","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130488252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving Streaming Capacity in Multi-Channel P2P VoD Systems via Intra-Channel and Cross-Channel Resource Allocation","authors":"Yifeng He, L. Guan","doi":"10.1155/2012/807520","DOIUrl":"https://doi.org/10.1155/2012/807520","url":null,"abstract":"Multi-channel Peer-to-Peer (P2P) Video-on-Demand\u0000(VoD) systems can be categorized into independent-channel P2P\u0000VoD systems and correlated-channel P2P VoD systems. Streaming\u0000capacity for a channel is defined as the maximal streaming\u0000rate that can be received by every user of the channel. In this\u0000paper, we study the streaming capacity problem in multi-channel\u0000P2P VoD systems. In an independent-channel P2P VoD system,\u0000there is no resource correlation among channels. Therefore, we\u0000can find the average streaming capacity for the independent-channel\u0000P2P VoD system by finding the streaming capacity for\u0000each individual channel, respectively. We propose a distributed\u0000algorithm to solve the streaming capacity problem for a single\u0000channel in an independent-channel P2P VoD system. The average\u0000streaming capacity for a correlated-channel P2P VoD system\u0000depends on both the intra-channel and cross-channel resource\u0000allocation. To better utilize the cross-channel resources, we\u0000first optimize the server upload allocation among channels to\u0000maximize the average streaming capacity and then propose\u0000cross-channel helpers to enable cross-channel sharing of peer\u0000upload bandwidths. We demonstrate in the simulations that the\u0000correlated-channel P2P VoD systems with both intra-channel and\u0000cross-channel resource allocation can obtain a higher average\u0000streaming capacity compared to the independent-channel P2P\u0000VoD systems with only intra-channel resource allocation.","PeriodicalId":204253,"journal":{"name":"Int. J. Digit. Multim. Broadcast.","volume":"263 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116074903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Gain-Computation Enhancements Resource Allocation for Heterogeneous Service Flows in IEEE 802.16 m Mobile Networks","authors":"W. B. Hassen, Mériem Afif","doi":"10.1155/2012/431958","DOIUrl":"https://doi.org/10.1155/2012/431958","url":null,"abstract":"This paper deals with radio resource allocation in fourth generation (4G) wireless mobile networks based on Orthogonal Frequency Division Multiple Access (OFDMA) as \u0000an access method. In IEEE 802.16 m standard, a contiguous method for subchannel construction is adopted in order to reduce OFDMA system complexity. In this context, we propose a new subchannel gain computation method depending on frequency responses dispersion. This method has a crucial role in the resource management and optimization. In a single service access, we propose a dynamic resource allocation algorithm at the physical layer aiming to maximize the cell data rate while ensuring fairness among users. In heterogeneous data traffics, we study scheduling in order to provide delay guaranties to real-time services, maximize throughput of non-real-time services while ensuring fairness to users. We compare performances to recent existing algorithms in OFDMA systems showing that proposed schemes provide lower complexity, higher total system capacity, and fairness among users.","PeriodicalId":204253,"journal":{"name":"Int. J. Digit. Multim. Broadcast.","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121628008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}