International Journal of Digital Multimedia Broadcasting http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. A Model for Video Quality Assessment Considering Packet Loss for Broadcast Digital Television Coded in H.264 Thu, 03 Apr 2014 11:15:53 +0000 http://www.hindawi.com/journals/ijdmb/2014/242531/ This paper presents a model to predict video quality perceived by the broadcast digital television (DTV) viewer. We present how noise on DTV can introduce individual transport stream (TS) packet losses at the receiver. The type of these errors is different than the produced on IP networks. Different scenarios of TS packet loss are analyzed, including uniform and burst distributions. The results show that there is a high variability on the perceived quality for a given percentage of packet loss and type of error. This implies that there is practically no correlation between the type of error or the percentage of packets loss and the perceived degradation. A new metric is introduced, the weighted percentage of slice loss, which takes into account the affected slice type in each lost TS packet. We show that this metric is correlated with the video quality degradation. A novel parametric model for video quality estimation is proposed, designed, and verified based on the results of subjective tests in SD and HD. The results were compared to a standard model used in IP transmission scenarios. The proposed model improves Pearson Correlation and root mean square error between the subjective and the predicted MOS. Jose Joskowicz and Rafael Sotelo Copyright © 2014 Jose Joskowicz and Rafael Sotelo. All rights reserved. Performance Evaluation of Concurrent Multipath Video Streaming in Multihomed Mobile Networks Mon, 26 Aug 2013 16:12:34 +0000 http://www.hindawi.com/journals/ijdmb/2013/319594/ High-quality real-time video streaming to users in mobile networks is challenging due to the dynamically changing nature of the network paths, particularly the limited bandwidth and varying end-to-end delay. In this paper, we empirically investigate the performance of multipath streaming in the context of multihomed mobile networks. Existing schemes that make use of the aggregated bandwidth of multiple paths can overcome bandwidth limitations on a single path but suffer an efficiency penalty caused by retransmission of lost packets in reliable transport schemes or path switching overheads in unreliable transport schemes. This work focuses on the evaluation of schemes to permit concurrent use of multiple paths to deliver video streams. A comprehensive streaming framework for concurrent multipath video streaming is proposed and experimentally evaluated, using current state-of-the-art H.264 Scalable Video Coding (H.264/SVC) and the next generation High Efficiency Video Coding (HEVC) standards. It provides a valuable insight into the benefit of using such schemes in conjunction with encoder specific packet prioritisation mechanisms for quality-aware packet scheduling and scalable streaming. The remaining obstacles to deployment of concurrent multipath schemes are identified, and the challenges in realising HEVC based concurrent multipath streaming are highlighted. James Nightingale, Qi Wang, and Christos Grecos Copyright © 2013 James Nightingale et al. All rights reserved. Optimization of ATSC Mobile Handheld Service Capacity Sun, 24 Mar 2013 10:01:08 +0000 http://www.hindawi.com/journals/ijdmb/2013/837153/ Mobile TV has become a reality offered on several mobile delivery systems. Among them is the Advanced Television System Committee (ATSC) system for mobile and handheld digital television services, known as ATSC Mobile DTV or ATSC M/H, which has moved from standardization to implementation. As the North American broadcast industry is preparing to provide Mobile DTV service to consumers, this work discusses important technical parameters that affect the TV service quality and capacity. Since additional error correction mechanisms were added to overcome mobile transmission problems, the available payload for M/H services is limited. This creates a need to efficiently use the available M/H bandwidth. The paper aims to optimize the Mobile DTV service capacity while maintaining an acceptable perceived quality. It presents tradeoffs between several factors affecting service capacity and signal robustness, which is prominent for designing Mobile TV broadcasting scenarios. Omneya Issa Copyright © 2013 Omneya Issa. All rights reserved. Bandwidth Management in Wireless Home Networks for IPTV Solutions Tue, 05 Mar 2013 10:55:14 +0000 http://www.hindawi.com/journals/ijdmb/2013/474212/ The optimal allocation of the retransmission bandwidth is essential for IPTV service providers to ensure maximal service quality. This paper highlights the relevance of the wireless transport in today’s IPTV solution and discusses how this new media affects the existing broadcast technologies. A new Markovian channel model is developed to address the optimization issues of the retransmission throughput, and a new method is presented which is evaluated by empirical measurements followed by mathematical analysis. Tamás Jursonovics and Sándor Imre Copyright © 2013 Tamás Jursonovics and Sándor Imre. All rights reserved. Client-Driven Joint Cache Management and Rate Adaptation for Dynamic Adaptive Streaming over HTTP Wed, 27 Feb 2013 12:30:10 +0000 http://www.hindawi.com/journals/ijdmb/2013/471683/ Due to the fact that proxy-driven proxy cache management and the client-driven streaming solution of Dynamic Adaptive Streaming over HTTP (DASH) are two independent processes, some difficulties and challenges arise in media data management at the proxy cache and rate adaptation at the DASH client. This paper presents a novel client-driven joint proxy cache management and DASH rate adaptation method, named CLICRA, which moves prefetching intelligence from the proxy cache to the client. Based on the philosophy of CLICRA, this paper proposes a rate adaptation algorithm, which selects bitrates for the next media segments to be requested by using the predicted buffered media time in the client. CLICRA is realized by conveying information on the segments that are likely to be fetched subsequently to the proxy cache so that it can use the information for prefetching. Simulation results show that the proposed method outperforms the conventional segment-fetch-time-based rate adaptation and the proxy-driven proxy cache management significantly not only in streaming quality at the client but also in bandwidth and storage usage in proxy caches. Chenghao Liu, Miska M. Hannuksela, and Moncef Gabbouj Copyright © 2013 Chenghao Liu et al. All rights reserved. PAPR Reduction of OFDM Signals by Novel Global Harmony Search in PTS Scheme Thu, 06 Dec 2012 13:54:10 +0000 http://www.hindawi.com/journals/ijdmb/2012/940849/ The orthogonal frequency division multiplexing (OFDM) modulation technique is one of the key strategies for multiuser signal transmission especially in smart grids and wind farms. This paper introduces an approach for peak-to-average power ratio (PAPR) reduction of such signals based on novel global harmony search (NGHS) and partial transmit sequence (PTS) schemes. In PTS technique, the data block to be transmitted is partitioned into disjoint subblocks, which are combined using phase factors to minimize PAPR. The PTS requires an exhaustive search over all combinations of allowed phase factors. Therefore, with respect to the fast implementation and simplicity of NGHS technique, we could achieve significant reduction of PAPR. Hojjat Salehinejad and Siamak Talebi Copyright © 2012 Hojjat Salehinejad and Siamak Talebi. All rights reserved. IPTV: Technology, Practice, and Service Sun, 26 Aug 2012 08:29:00 +0000 http://www.hindawi.com/journals/ijdmb/2012/734769/ Hsiang-Fu Yu, Jen-Wen Ding, Pin-Han Ho, and János Tapolcai Copyright © 2012 Hsiang-Fu Yu et al. All rights reserved. Background Traffic-Based Retransmission Algorithm for Multimedia Streaming Transfer over Concurrent Multipaths Mon, 13 Aug 2012 10:21:32 +0000 http://www.hindawi.com/journals/ijdmb/2012/789579/ The content-rich multimedia streaming will be the most attractive services in the next-generation networks. With function of distribute data across multipath end-to-end paths based on SCTP's multihoming feature, concurrent multipath transfer SCTP (CMT-SCTP) has been regarded as the most promising technology for the efficient multimedia streaming transmission. However, the current researches on CMT-SCTP mainly focus on the algorithms related to the data delivery performance while they seldom consider the background traffic factors. Actually, background traffic of realistic network environments has an important impact on the performance of CMT-SCTP. In this paper, we firstly investigate the effect of background traffic on the performance of CMT-SCTP based on a close realistic simulation topology with reasonable background traffic in NS2, and then based on the localness nature of background flow, a further improved retransmission algorithm, named RTX_CSI, is proposed to reach more benefits in terms of average throughput and achieve high users' experience of quality for multimedia streaming services. Yuanlong Cao, Changqiao Xu, Jianfeng Guan, and Hongke Zhang Copyright © 2012 Yuanlong Cao et al. All rights reserved. Secure and Reliable IPTV Multimedia Transmission Using Forward Error Correction Sun, 08 Jul 2012 10:42:03 +0000 http://www.hindawi.com/journals/ijdmb/2012/720791/ With the wide deployment of Internet Protocol (IP) infrastructure and rapid development of digital technologies, Internet Protocol Television (IPTV) has emerged as one of the major multimedia access techniques. A general IPTV transmission system employs both encryption and forward error correction (FEC) to provide the authorized subscriber with a high-quality perceptual experience. This two-layer processing, however, complicates the system design in terms of computational cost and management cost. In this paper, we propose a novel FEC scheme to ensure the secure and reliable transmission for IPTV multimedia content and services. The proposed secure FEC utilizes the characteristics of FEC including the FEC-encoded redundancies and the limitation of error correction capacity to protect the multimedia packets against the malicious attacks and data transmission errors/losses. Experimental results demonstrate that the proposed scheme obtains similar performance compared with the joint encryption and FEC scheme. Chi-Huang Shih, Yeong-Yuh Xu, and Yao-Tien Wang Copyright © 2012 Chi-Huang Shih et al. All rights reserved. Automatic Story Segmentation for TV News Video Using Multiple Modalities Thu, 05 Jul 2012 10:04:20 +0000 http://www.hindawi.com/journals/ijdmb/2012/732514/ While video content is often stored in rather large files or broadcasted in continuous streams, users are often interested in retrieving only a particular passage on a topic of interest to them. It is, therefore, necessary to split video documents or streams into shorter segments corresponding to appropriate retrieval units. We propose here a method for the automatic segmentation of TV news videos into stories. A-multiple-descriptor based segmentation approach is proposed. The selected multimodal features are complementary and give good insights about story boundaries. Once extracted, these features are expanded with a local temporal context and combined by an early fusion process. The story boundaries are then predicted using machine learning techniques. We investigate the system by experiments conducted using TRECVID 2003 data and protocol of the story boundary detection task, and we show that the proposed approach outperforms the state-of-the-art methods while requiring a very small amount of manual annotation. Émilie Dumont and Georges Quénot Copyright © 2012 Émilie Dumont and Georges Quénot. All rights reserved. QoS Supported IPTV Service Architecture over Hybrid-Tree-Based Explicit Routed Multicast Network Tue, 03 Jul 2012 08:43:47 +0000 http://www.hindawi.com/journals/ijdmb/2012/263470/ With the rapid advance in multimedia streaming and multicast transport technology, current IP multicast protocols, especially PIM-SM, become the major channel delivery mechanism for IPTV system over Internet. The goals for IPTV service are to provide two-way interactive services for viewers to select popular program channel with high quality for watching during fast channel surfing period. However, existing IP multicast protocol cannot meet above QoS requirements for IPTV applications between media server and subscribers. Therefore, we propose a cooperative scheme of hybrid-tree based on explicit routed multicast, called as HT-ERM to combine the advantages of shared tree and source tree for QoS-supported IPTV service. To increase network utilization, the constrained shortest path first (CSPF) routing algorithm is designed for construction of hybrid tree to deliver the high-quality video stream over watching channel and standard quality over surfing channel. Furthermore, the Resource Reservation Protocol- Traffic Engineering (RSVP-TE) is used as signaling mechanism to set up QoS path for multicast channel admission control. Our simulation results demonstrated that the proposed HT-ERM scheme outperforms other multicast QoS-based delivery scheme in terms of channel switching delay, resource utilization, and blocking ratio for IPTV service. Chih-Chao Wen and Cheng-Shong Wu Copyright © 2012 Chih-Chao Wen and Cheng-Shong Wu. All rights reserved. Rate Adaptive Selective Segment Assignment for Reliable Wireless Video Transmission Wed, 27 Jun 2012 10:41:27 +0000 http://www.hindawi.com/journals/ijdmb/2012/160521/ A reliable video communication system is proposed based on data partitioning feature of H.264/AVC, used to create a layered stream, and LT codes for erasure protection. The proposed scheme termed rate adaptive selective segment assignment (RASSA) is an adaptive low-complexity solution to varying channel conditions. The comparison of the results of the proposed scheme is also provided for slice-partitioned H.264/AVC data. Simulation results show competitiveness of the proposed scheme compared to optimized unequal and equal error protection solutions. The simulation results also demonstrate that a high visual quality video transmission can be maintained despite the adverse effect of varying channel conditions and the number of decoding failures can be reduced. Sajid Nazir, Dejan Vukobratović, Vladimir Stanković, and Ivan Andonović Copyright © 2012 Sajid Nazir et al. All rights reserved. A Secure and Stable Multicast Overlay Network with Load Balancing for Scalable IPTV Services Thu, 07 Jun 2012 11:05:11 +0000 http://www.hindawi.com/journals/ijdmb/2012/540801/ The emerging multimedia Internet application IPTV over P2P network preserves significant advantages in scalability. IPTV media content delivered in P2P networks over public Internet still preserves the issues of privacy and intellectual property rights. In this paper, we use SIP protocol to construct a secure application-layer multicast overlay network for IPTV, called SIPTVMON. SIPTVMON can secure all the IPTV media delivery paths against eavesdroppers via elliptic-curve Diffie-Hellman (ECDH) key exchange on SIP signaling and AES encryption. Its load-balancing overlay tree is also optimized from peer heterogeneity and churn of peer joining and leaving to minimize both service degradation and latency. The performance results from large-scale simulations and experiments on different optimization criteria demonstrate SIPTVMON's cost effectiveness in quality of privacy protection, stability from user churn, and good perceptual quality of objective PSNR values for scalable IPTV services over Internet. Tsao-Ta Wei, Chia-Hui Wang, Yu-Hsien Chu, and Ray-I Chang Copyright © 2012 Tsao-Ta Wei et al. All rights reserved. Video Classification and Adaptive QoP/QoS Control for Multiresolution Video Applications on IPTV Wed, 30 May 2012 10:51:39 +0000 http://www.hindawi.com/journals/ijdmb/2012/801641/ With the development of heterogeneous networks and video coding standards, multiresolution video applications over networks become important. It is critical to ensure the service quality of the network for time-sensitive video services. Worldwide Interoperability for Microwave Access (WIMAX) is a good candidate for delivering video signals because through WIMAX the delivery quality based on the quality-of-service (QoS) setting can be guaranteed. The selection of suitable QoS parameters is, however, not trivial for service users. Instead, what a video service user really concerns with is the video quality of presentation (QoP) which includes the video resolution, the fidelity, and the frame rate. In this paper, we present a quality control mechanism in multiresolution video coding structures over WIMAX networks and also investigate the relationship between QoP and QoS in end-to-end connections. Consequently, the video presentation quality can be simply mapped to the network requirements by a mapping table, and then the end-to-end QoS is achieved. We performed experiments with multiresolution MPEG coding over WIMAX networks. In addition to the QoP parameters, the video characteristics, such as, the picture activity and the video mobility, also affect the QoS significantly. Huang Shyh-Fang Copyright © 2012 Huang Shyh-Fang. All rights reserved. Adjustable Two-Tier Cache for IPTV Based on Segmented Streaming Mon, 21 May 2012 11:19:20 +0000 http://www.hindawi.com/journals/ijdmb/2012/192314/ 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. Kai-Chun Liang and Hsiang-Fu Yu Copyright © 2012 Kai-Chun Liang and Hsiang-Fu Yu. All rights reserved. Monitoring Accessibility Services in Digital Television Wed, 16 May 2012 08:29:24 +0000 http://www.hindawi.com/journals/ijdmb/2012/294219/ 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. Francisco Utray, Mercedes de Castro, Lourdes Moreno, and Belén Ruiz-Mezcua Copyright © 2012 Francisco Utray et al. All rights reserved. A Seamless Broadcasting Scheme with Live Video Support Tue, 24 Apr 2012 07:55:42 +0000 http://www.hindawi.com/journals/ijdmb/2012/373459/ 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. Zeng-Yuan Yang, Yi-Ming Chen, and Li-Ming Tseng Copyright © 2012 Zeng-Yuan Yang et al. All rights reserved. An Efficient Periodic Broadcasting with Small Latency and Buffer Demand for Near Video on Demand Mon, 09 Apr 2012 10:16:50 +0000 http://www.hindawi.com/journals/ijdmb/2012/717538/ 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. Ying-Nan Chen and Li-Ming Tseng Copyright © 2012 Ying-Nan Chen and Li-Ming Tseng. All rights reserved. Communications and Networking for Smart Grid: Technology and Practice Thu, 05 Apr 2012 09:00:57 +0000 http://www.hindawi.com/journals/ijdmb/2011/617624/ Chi Zhou, Hossam S. Hassanein, Robert Qiu, and Pierangela Samarati Copyright © 2011 Chi Zhou et al. All rights reserved. Efficient Wireless Broadcasting through Joint Network Coding and Beamforming Sun, 18 Mar 2012 15:00:28 +0000 http://www.hindawi.com/journals/ijdmb/2012/342512/ 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. Monchai Lertsutthiwong, Thinh Nguyen, and Bechir Hamdaoui Copyright © 2012 Monchai Lertsutthiwong et al. All rights reserved. LDPC FEC Code Extension for Unequal Error Protection in DVB-T2 System: Design and Evaluation Sun, 11 Mar 2012 10:36:52 +0000 http://www.hindawi.com/journals/ijdmb/2012/834924/ 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. Lukasz Kondrad, Imed Bouazizi, and Moncef Gabbouj Copyright © 2012 Lukasz Kondrad et al. All rights reserved. A Low-Complexity Resource Allocation Algorithm for MIMO-OFDMA Multicast Systems with Spectrum-Guarantee Provisioning Thu, 08 Mar 2012 14:32:15 +0000 http://www.hindawi.com/journals/ijdmb/2012/585267/ 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. Ioannis G. Fraimis and Stavros A. Kotsopoulos Copyright © 2012 Ioannis G. Fraimis and Stavros A. Kotsopoulos. All rights reserved. Cloud Computing and Dynamic Resource Allocation for Multimedia Applications Thu, 01 Mar 2012 11:54:05 +0000 http://www.hindawi.com/journals/ijdmb/2012/238460/ Yifeng He, Ling Guan, Wenwu Zhu, and Ivan Lee Copyright © 2012 Yifeng He et al. All rights reserved. Improving Streaming Capacity in Multi-Channel P2P VoD Systems via Intra-Channel and Cross-Channel Resource Allocation Wed, 29 Feb 2012 08:13:37 +0000 http://www.hindawi.com/journals/ijdmb/2012/807520/ Multi-channel Peer-to-Peer (P2P) Video-on-Demand (VoD) systems can be categorized into independent-channel P2P VoD systems and correlated-channel P2P VoD systems. Streaming capacity for a channel is defined as the maximal streaming rate that can be received by every user of the channel. In this paper, we study the streaming capacity problem in multi-channel P2P VoD systems. In an independent-channel P2P VoD system, there is no resource correlation among channels. Therefore, we can find the average streaming capacity for the independent-channel P2P VoD system by finding the streaming capacity for each individual channel, respectively. We propose a distributed algorithm to solve the streaming capacity problem for a single channel in an independent-channel P2P VoD system. The average streaming capacity for a correlated-channel P2P VoD system depends on both the intra-channel and cross-channel resource allocation. To better utilize the cross-channel resources, we first optimize the server upload allocation among channels to maximize the average streaming capacity and then propose cross-channel helpers to enable cross-channel sharing of peer upload bandwidths. We demonstrate in the simulations that the correlated-channel P2P VoD systems with both intra-channel and cross-channel resource allocation can obtain a higher average streaming capacity compared to the independent-channel P2P VoD systems with only intra-channel resource allocation. Yifeng He and Ling Guan Copyright © 2012 Yifeng He and Ling Guan. All rights reserved. A Gain-Computation Enhancements Resource Allocation for Heterogeneous Service Flows in IEEE 802.16 m Mobile Networks Thu, 09 Feb 2012 16:16:34 +0000 http://www.hindawi.com/journals/ijdmb/2012/431958/ This paper deals with radio resource allocation in fourth generation (4G) wireless mobile networks based on Orthogonal Frequency Division Multiple Access (OFDMA) as an 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. Wafa Ben Hassen and Meriem Afif Copyright © 2012 Wafa Ben Hassen and Meriem Afif. All rights reserved. Performance Evaluation of an Object Management Policy Approach for P2P Networks Tue, 07 Feb 2012 11:41:27 +0000 http://www.hindawi.com/journals/ijdmb/2012/189325/ The increasing popularity of network-based multimedia applications poses many challenges for content providers to supply efficient and scalable services. Peer-to-peer (P2P) systems have been shown to be a promising approach to provide large-scale video services over the Internet since, by nature, these systems show high scalability and robustness. In this paper, we propose and analyze an object management policy approach for video web cache in a P2P context, taking advantage of object's metadata, for example, video popularity, and object's encoding techniques, for example, scalable video coding (SVC). We carry out trace-driven simulations so as to evaluate the performance of our approach and compare it against traditional object management policy approaches. In addition, we study as well the impact of churn on our approach and on other object management policies that implement different caching strategies. A YouTube video collection which records over 1.6 million video's log was used in our experimental studies. The experiment results have showed that our proposed approach can improve the performance of the cache substantially. Moreover, we have found that neither the simply enlargement of peers' storage capacity nor a zero replicating strategy is effective actions to improve performance of an object management policy. Dario Vieira, Cesar A. V. Melo, and Yacine Ghamri-Doudane Copyright © 2012 Dario Vieira et al. All rights reserved. Multi-Objective Genetic Algorithm for Task Assignment on Heterogeneous Nodes Thu, 19 Jan 2012 14:55:00 +0000 http://www.hindawi.com/journals/ijdmb/2012/716780/ Task assignment in grid computing, where both processing and bandwidth constraints at multiple heterogeneous devices need to be considered, is a challenging problem. Moreover, targeting the optimization of multiple objectives makes it even more challenging. This paper presents a task assignment strategy based on genetic algorithms in which multiple and conflicting objectives are simultaneously optimized. Specifically, we maximize task execution quality while minimizing energy and bandwidth consumption. Moreover, in our video processing scenario; we consider transcoding to lower spatial/temporal resolutions to tradeoff between video quality; processing, and bandwidth demands. The task execution quality is then determined by the number of successfully processed streams and the spatial-temporal resolution at which they are processed. The results show that the proposed algorithm offers a range of Pareto optimal solutions that outperforms all other reference strategies. Carolina Blanch Perez del Notario, Rogier Baert, and Maja D'Hondt Copyright © 2012 Carolina Blanch Perez del Notario et al. All rights reserved. Towards an Automatic Parameter-Tuning Framework for Cost Optimization on Video Encoding Cloud Wed, 18 Jan 2012 12:55:09 +0000 http://www.hindawi.com/journals/ijdmb/2012/935724/ The emergence of cloud encoding services facilitates many content owners, such as the online video vendors, to transcode their digital videos without infrastructure setup. Such service provider charges the customers only based on their resource consumption. For both the service provider and customers, lowering the resource consumption while maintaining the quality is valuable and desirable. Thus, to choose a cost-effective encoding parameter, configuration is essential and challenging due to the tradeoff between bitrate, encoding speed, and resulting quality. In this paper, we explore the feasibility of an automatic parameter-tuning framework, based on which the above objective can be achieved. We introduce a simple service model, which combines the bitrate and encoding speed into a single value: encoding cost. Then, we conduct an empirical study to examine the relationship between the encoding cost and various parameter settings. Our experiment is based on the one-pass Constant Rate Factor method in x264, which can achieve relatively stable perceptive quality, and we vary each parameter we choose to observe how the encoding cost changes. 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 optimizing the cost on video encoding cloud. Xiaowei Li, Yi Cui, and Yuan Xue Copyright © 2012 Xiaowei Li et al. All rights reserved. Multi-Resolution Multimedia QoE Models for IPTV Applications Thu, 12 Jan 2012 18:40:50 +0000 http://www.hindawi.com/journals/ijdmb/2012/904072/ Internet television (IPTV) is rapidly gaining popularity and is being widely deployed in content delivery networks on the Internet. In order to proactively deliver optimum user quality of experience (QoE) for IPTV, service providers need to identify network bottlenecks in real time. In this paper, we develop psycho-acoustic-visual models that can predict user QoE of multimedia applications in real time based on online network status measurements. Our models are neural network based and cater to multi-resolution IPTV applications that include QCIF, QVGA, SD, and HD resolutions encoded using popular audio and video codec combinations. On the network side, our models account for jitter and loss levels, as well as router queuing disciplines: packet-ordered and time-ordered FIFO. We evaluate the performance of our multi-resolution multimedia QoE models in terms of prediction characteristics, accuracy, speed, and consistency. Our evaluation results demonstrate that the models are pertinent for real-time QoE monitoring and resource adaptation in IPTV content delivery networks. Prasad Calyam, Prashanth Chandrasekaran, Gregg Trueb, Nathan Howes, Rajiv Ramnath, Delei Yu, Ying Liu, Lixia Xiong, and Daoyan Yang Copyright © 2012 Prasad Calyam et al. All rights reserved. Cyber Security for Smart Grid, Cryptography, and Privacy Tue, 04 Oct 2011 15:15:15 +0000 http://www.hindawi.com/journals/ijdmb/2011/372020/ The invention of “smart grid” promises to improve the efficiency and reliability of the power system. As smart grid is turning out to be one of the most promising technologies, its security concerns are becoming more crucial. The grid is susceptible to different types of attacks. This paper will focus on these threats and risks especially relating to cyber security. Cyber security is a vital topic, since the smart grid uses high level of computation like the IT. We will also see cryptography and key management techniques that are required to overcome these attacks. Privacy of consumers is another important security concern that this paper will deal with. Swapna Iyer Copyright © 2011 Swapna Iyer. All rights reserved.