http://www.hindawi.comThe latest articles from Hindawi Publishing Corporation© 2012, Hindawi Publishing Corporation. All rights reserved.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 YangCopyright © 2012 Prasad Calyam et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2011/857847/Network coding was introduced by Ahlswede et al. in a pioneering work in 2000. This paradigm encompasses coding and retransmission of messages at the intermediate nodes of the network. In contrast with traditional store-and-forward networking, network coding increases the throughput and the robustness of the transmission. Linear network coding is a practical implementation of this new paradigm covered by several research works that include rate characterization, error-protection coding, and construction of codes. Especially determining the coding characteristics has its importance in providing the premise for an efficient transmission. In this paper, we review the recent breakthroughs in linear network coding for acyclic networks with a survey of code constructions literature. Deterministic construction algorithms and randomized procedures are presented for traditional network coding and for network-control network coding.Michele Sanna and Ebroul IzquierdoCopyright © 2011 Michele Sanna and Ebroul Izquierdo. All rights reserved.http://www.hindawi.com/journals/ijdmb/2011/470310/Tone Reservation (TR) is a technique proposed to combat the high Peak-to-Average Power Ratio (PAPR) problem of Orthogonal Frequency Division Multiplexing (OFDM) signals. However conventional TR suffers from high computational cost due to the difficulties in finding an effective cancellation signal in the time domain by using only a few tones in the frequency domain. It also suffers from a high cost of hardware implementation and long handling time delay issues due to the need to conduct multiple iterations to cancel multiple high signal peaks. In this paper, we propose an efficient approach, called two-threshold parallel scaling, for implementing a previously proposed Gaussian pulse-based Tone Reservation algorithm. Compared to conventional approaches, this technique significantly reduces the hardware implementation complexity and cost, while also reducing signal processing time delay by using just two iterations. Experimental results show that the proposed technique can effectively reduce the PAPR of OFDM signals with only a very small number of reserved tones and with limited usage of hardware resources. This technique is suitable for any OFDM-based communication systems, especially for Digital Video Broadcasting (DVB) systems employing large IFFT/FFT transforms.Lei Guan and Anding ZhuCopyright © 2011 Lei Guan and Anding Zhu. All rights reserved.http://www.hindawi.com/journals/ijdmb/2011/687071/This paper provides an innovative solution, namely, the distributed storage manager that opens a new path for highly interactive and personalized services. The distributed storage manager provides an enhancement to the MHP storage management functionality acting as a value added middleware distributed across the network. The distributed storage manager system provides multiple protocol support for initializing and downloading both streamed and file-based content and provides optimum control mechanisms to organize the storing and retrieval of content that are remained accessible to other multiple heterogeneous devices.Frank X. Sun, John Cosmas, Muhammad Ali Farmer, and Abdul WaheedCopyright © 2011 Frank X. Sun et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2011/310647/Wireless personal area networks (WPANs) are getting popular in a variety of fields such as smart home, office automation, and e-healthcare. In WPANs, most devices are considerably energy constrained, so the communication protocol should be energy efficient. The IEEE 802.15.4 is designed as a standard protocol for low power, low data rate, low complexity, and short range connections in WPANs. The standard supports allocating several numbers of collision-free guarantee time slots (GTSs) within a superframe for some time-critical transmissions. Recently, COPE was proposed as a promising network coding architecture to essentially improve the throughput of wireless networks. In this paper, we exploit the network coding technique at coordinators to improve energy efficiency of the WPAN. Some related practical issues, such as GTS allocation and multicast, are also discussed in order to exploit the network coding opportunities efficiently. Since the coding opportunities are mostly exploited, our proposal achieves both higher energy efficiency and throughput performance than the original IEEE 802.15.4.Deze Zeng, Song Guo, Victor Leung, and Jiankun HuCopyright © 2011 Deze Zeng et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2011/786915/Energy saving and high delivery reliability are two essential metrics in wireless ad hoc networks. In this paper, we propose a joint power control and network coding (PCNC) scheme which regulates the transmission power to reduce the overall energy usage and uses network coding to improve reliability by reducing the number of packet retransmissions. To argue for PCNC scheme, we investigate both unicast and multicast routing scenarios. To evaluate routing optimality, we adopt expected utility as a metric, which integrates energy cost, reliability, and benefit value. Based on the expected utility, we explore the optimality in both unicast and multicast routing. For unicast routing, we propose an optimal algorithm. We show the NP-hardness of multicast routing problem, and also design a heuristic solution. Results from simulations demonstrate that PCNC improves the performance in terms of expected utility compared with existing techniques.Kaiqian Ou, Yinlong Xu, Xiumin Wang, and Wang LiuCopyright © 2011 Kaiqian Ou et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2011/365896/A novel peak-to-average power ratio (PAPR) reduction technique for orthogonal frequency division multiplexing (OFDM) systems is addressed. Instead of using dedicated pilots for PAPR reduction as with tone reservation (TR) method selected by the DVB-T2 standard, we propose to use existing pilots used for channel estimation. In this way, we avoid the use of reserved tone pilots and then improve the spectral efficiency of the system. In order to allow their recovery at the receiver, these pilots have to follow particular laws which permit their blind detection and avoid sending side information. In this work, we propose and investigate a multiplicative law operating in discrete frequency domain. The operation in discrete domain aims at reducing degradation due to detection and estimation error in continuous domain. Simulation results are performed using the new DVB-T2 standard parameters. Its performance is compared to the DVB-T2 PAPR gradient algorithm and to the second-order cone programming (SOCP) competitive technique proposed in the literature. We show that the proposed technique is efficient in terms of PAPR reduction value and of spectral efficiency while the channel estimation performance is maintained.Anh-Tai Ho, Jean-François Helard, Youssef Nasser, and Yves LouetCopyright © 2011 Anh-Tai Ho et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/597105/We investigate into the potentiality of an enhanced Power and Location-based Vertical Handover (PLB-VHO) approach, based on a combination of physical parameters (i.e., location and power attenuation information), for mobile-controlled connectivity across UMTS and WLAN networks. We show that the location information in a multiparameter vertical handover can significantly enhance communication performance. In the presented approach a power attenuation map for the visited area is built and kept updated by exploiting the information sharing of power measurements with other cooperating mobile devices inside the visited networks. Such information is then used for connectivity switching in handover decisions. The analytical model for the proposed technique is first presented and then compared with a traditional Power-Based approach and a simplified Location-Based technique. Simulation results show the effectiveness of PLB-VHO approach, in terms of (i) network performance optimization and (ii) limitation of unnecessary handovers (i.e., mitigation of ping-pong effect).T. Inzerilli, Anna Maria Vegni, A. Neri, and R. CusaniCopyright © 2010 T. Inzerilli et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/108726/A system data sharing protocol of mobile WSN named synchronous dynamic multihop data sharing protocol (S-DMDS) is presented for automated guided vehicle (AGV) system. It is a cross-layer protocol designed from route layer to MAC layer. By adopting a concept of system data sharing, it is possible to make each node exchange the data timely with all the other nodes. It is also a topology-agnostic protocol which has no knowledge of neighbors, routes, or next hops. From the results of the 16-nodes simulation, S-DMDS protocol is proved to be efficient exchange data timely between the devices of AGV system in mobile multihop situation. Moreover, it also shows that S-DMDS significantly outperforms NST-AODV with investing about 41.6% system sharing delay as well as 80% RAM consumption. At last, 5-node experiment indicates that S-DMDS can work well in real environment.Jiaqi Zhang, Molin Jia, Noriyoshi Yamauchi, and Takaaki BabaCopyright © 2010 Jiaqi Zhang et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/397824/This paper is focused on the problem of optimizing the aggregate throughput of the distributed coordination function (DCF) employing the basic access mechanism at the data link layer of IEEE 802.11 protocols. We consider general operating conditions accounting for both nonsaturated and saturated traffic in the presence of transmission channel errors, as exemplified by the packet error rate Pe. The main clue of this work stems from the relation that links the aggregate throughput of the network to the packet rate λ of the contending stations. In particular, we show that the aggregate throughput S(λ) presents two clearly distinct operating regions that depend on the actual value of the packet rate λ with respect to a critical value λc, theoretically derived in this work. The behavior of S(λ) paves the way to a cross-layer optimization algorithm, which proved to be effective for maximizing the aggregate throughput in a variety of network operating conditions. A nice consequence of the proposed optimization framework relies on the fact that the aggregate throughput can be predicted quite accurately with a simple, yet effective, closed-form expression. Finally, theoretical and simulation results are presented in order to unveil, as well as verify, the key ideas.Massimiliano Laddomada and Fabio MesitiCopyright © 2010 Massimiliano Laddomada and Fabio Mesiti. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/741792/We propose an idle probability-based broadcasting method, iPro, which employs an adaptive probabilistic mechanism to improve performance of data broadcasting over dense wireless ad hoc networks. In multisource one-hop broadcast scenarios, the modeling and simulation results of the proposed iPro are shown to significantly outperform the standard IEEE 802.11 under saturated condition. Moreover, the results also show that without estimating the number of competing nodes and changing the contention window size, the performance of the proposed iPro can still approach the theoretical bound. We further apply iPro to multihop broadcasting scenarios, and the experiment results show that within the same elapsed time after the broadcasting, the proposed iPro has significantly higher Packet-Delivery Ratios (PDR) than traditional methods.Victor Gau and Jenq-Neng HwangCopyright © 2010 Victor Gau and Jenq-Neng Hwang. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/689705/Interference coordination methods for Evolved-Multimedia Broadcast/Multicast Service (E-MBMS) in Long-Term Evolution Advanced (LTE-A) are presented. In addition, we consider signal space diversity based on Rotation Matrices (RM) known to provide good performance gains over uncorrelated Rayleigh fading channels. OFDM/OFDMA systems can make the use of RM very attractive both for single and multiple antenna transmissions. In this paper, OFDM/OFDMA signals based on LTE parameters are combined with RM, MIMO, Turbo, or LDPC codes. We have considered different types of receivers, namely, we used an MMSE (Minimum Mean Squared Error) equalizer and a Maximum Likelihood Soft Output criterion (MLSO). Frequency, signal, and space diversity gains are evaluated for different spatial channel models (SCM) based on ITU multipath propagation channels. Different adaptive frequency reuse and schedulers are considered to evaluate the E-MBMS spectral efficiency at the cell borders.Alberto A. Lopes, José Seguro, Paulo Gomes, Nuno Souto, and Américo CorreiaCopyright © 2010 Alberto A. Lopes et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/797393/High Peak to Average Power Ratio (PAPR) is a critical issue in multicarrier communication systems using Orthogonal Frequency Division Multiplexing (OFDM), as in the Second Generation Terrestrial Digital Video Broadcasting (DVB-T2) system. This problem can result in large performance degradation due to the nonlinearity of the High Power Amplifier (HPA) or in its low power efficiency. In this paper, we evaluate the performance of different Tone Reservation-based techniques for PAPR reduction in DVB-T2 context. Also, we propose an iterative TR-based technique called “One Kernel One Peak” (OKOP). Simulation results and performance comparison of these techniques in terms of gain in PAPR reduction, mean power variation, and complexity will be given. Finally, we describe the implementation of a PAPR reduction algorithm in the DVB-T2 modulator.Mohamad Mroué, Amor Nafkha, Jacques Palicot, Benjamin Gavalda, and Nelly DagorneCopyright © 2010 Mohamad Mroué et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/934896/An intra-vehicular wireless sensor network is designed and implemented on a software-defined radio system. IUWB signal is chosen to carry the data packets. The MAC layer of the system follows the specification of the IEEE802.15.4 standard. The transceiver design, especially the receiver design, is detailed in the paper. The system design is validated through lab test setup.Xiangming Kong, Deying Zhang, and Mohin AhmedCopyright © 2010 Xiangming Kong et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/645049/We investigate the video assignment problem of a hierarchical Video-on-Demand (VOD) system in heterogeneous environments where different quality levels of videos can be encoded using either replication or layering. In such systems, videos are delivered to clients either through a proxy server or video broadcast/unicast channels. The objective of our work is to determine the appropriate coding strategy as well as the suitable delivery mechanism for a specific quality level of a video such that the overall system blocking probability is minimized. In order to find a near-optimal solution for such a complex video assignment problem, an evolutionary approach based on genetic algorithm (GA) is proposed. From the results, it is shown that the system performance can be significantly enhanced by efficiently coupling the various techniques.King-Man Ho, Wing-Fai Poon, and Kwok-Tung LoCopyright © 2010 King-Man Ho et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/720251/P2P data storage requires strong reliability and security assurances. Existing data storage solutions have been designed for centralized as well as distributed settings; yet they do not address the security and cooperation issues raised by self-organization. P2P systems also introduce new needs regarding data availability due to the dynamicity of the infrastructure, which are unaddressed so far. This paper first discusses the approaches for tackling these problems. A solution is then introduced that relies on self-organizing security mechanisms in conjunction with a data rejuvenation scheme using erasure codes.Nouha Oualha, Melek Önen, and Yves RoudierCopyright © 2010 Nouha Oualha et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/417213/We discuss how a short-range wireless communication service implemented for modern mobile communication devices can provide additional value for both the consumer and the service/product provider. When used as an information search tool, such systems allow services and products being promoted at the location they are available. For the customer, it may provide a “digitally augmented vision”, an enhanced view to the current environment. With data filtering and search rules, this may provide a self-manageable context, where the user's own personal environment and preferences to the features available in the current surroundings cooperate with a direct connection to the web-based social media. A preliminary design for such service is provided. The conclusion is that the method can generate additional revenue to the company and please the customers' buying process. In addition to the marketing, the principles described here are also applicable to other forms of human interaction.Vesa A. Korhonen and Ritva PyykkönenCopyright © 2010 Vesa A. Korhonen and Ritva Pyykkönen. All rights reserved.http://www.hindawi.com/journals/ijdmb/2010/369814/Peer-to-Peer (P2P) file sharing is one of key technologies for achieving attractive P2P multimedia social networking. In P2P file-sharing systems, file availability is improved by cooperative users who cache and share files. Note that file caching carries costs such as storage consumption and processing load. In addition, users have different degrees of cooperativity in file caching and they are in different surrounding environments arising from the topological structure of P2P networks. With evolutionary game theory, this paper evaluates the performance of P2P file sharing systems in such heterogeneous environments. Using micro-macro dynamics, we analyze the impact of the heterogeneity of user selfishness on the file availability and system stability. Further, through simulation experiments with agent-based dynamics, we reveal how other aspects, for example, synchronization among nodes and topological structure, affect the system performance. Both analytical and simulation results show that the environmental heterogeneity contributes to the file availability and system stability.Yusuke Matsuda, Masahiro Sasabe, and Tetsuya TakineCopyright © 2010 Yusuke Matsuda et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2009/806750/Chroma is an important attribute of music and sound, although it has not yet been adequately defined in literature. As such, it can be used for further analysis of sound, resulting in interesting colorful representations that can be used in many tasks: indexing, classification, and retrieval. Especially in Music Information Retrieval (MIR), the visualization of the chromatic analysis can be used for comparison, pattern recognition, melodic sequence prediction, and color-based searching. MEL-IRIS is the tool which has been developed in order to analyze audio files and characterize music based on chroma. The tool implements specially designed algorithms and a unique way of visualization of the results. The tool is network-oriented and can be installed in audio servers, in order to manipulate large music collections. Several samples from world music have been tested and processed, in order to demonstrate the possible uses of such an analysis.Dimitrios Margounakis, Dionysios Politis, and Konstantinos MokosCopyright © 2009 Dimitrios Margounakis et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2009/879290/Adaptive Coding and Modulation (ACM) is a feature incorporated into the DVB-S2 satellite specification, allowing real-time adaptation of transmission parameters according to the link conditions. Although ACM was originally designed for optimizing unicast services, this article discusses the expansion of its usage to broadcasting streams as well. For this purpose, a general cross-layer adaptation approach is proposed, along with its realization into a fully functional experimental network, and test results are presented. Finally, two case studies are analysed, assessing the gain derived by ACM in a real large-scale deployment, involving HD services provision to two different geographical areas.Georgios Gardikis, Nikolaos Zotos, and Anastasios KourtisCopyright © 2009 Georgios Gardikis et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2009/261231/A novel technique for implementing statistical multiplexing (StatMux) of broadcast services over Digital Video Broadcasting for Handhelds (DVB-H) channels is proposed. DVB-H uses a time-sliced transmission scheme to reduce the power consumption used for radio reception part in DVB-H receivers. Due to the time-sliced transmission scheme, the implementation of known StatMux methods for DVB-H application presents some challenges which are addressed in this paper. The proposed StatMux technique is implemented in conjunction with the time-slicing transmission scheme. The combination is similar to a time division multiplexing (TDM) scheme. The proposed StatMux method considerably decreases the end-to-end delay of DVB-H services while it maximizes the usage of available bandwidth. Moreover, the proposed method can effectively decrease the channel switching delay of DVB-H services. Simulation results show a high performance for the proposed StatMux method.Mehdi Rezaei, Imed Bouazizi, and Moncef GabboujCopyright © 2009 Mehdi Rezaei et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2009/573404/Maximal-ratio combiner (MRC) performances in fading channels have been of interest for a long time, which can be seen by a number of papers concerning this topic. In this paper we treat bit error probability (BEP), symbol error probability (SEP) and outage probability of MRC in presence of κ‐μ fading. We will present κ‐μ fading model, probability density function (PDF), and cumulative distribution function (CDF). We will also present PDF, CDF, and outage probability of the L-branch MRC output. BEP/SEP will be evaluated for broad class of modulation types and for coherent and noncoherent types of detection. BEP/SEP and outage performances of the MRC will be evaluated for different number of branches via Monte Carlo simulations and theoretical expressions.Mirza Milišić, Mirza Hamza, and Mesud HadžialićCopyright © 2009 Mirza Milišić et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2008/250654/The current paper focuses on validating an implementation of a state-of-the art audiovisual (AV) technologies setup for live broadcasting of cultural shows, via broadband Internet. The main objective of the work was to study, configure, and setup dedicated audio-video equipment for the processes of capturing, processing, and transmission of extended resolution and high fidelity AV content in order to increase realism and achieve maximum audience sensation. Internet2 and GEANT broadband telecommunication networks were selected as the most applicable technology to deliver such traffic workloads. Validation procedures were conducted in combination with metric-based quality of service (QoS) and quality of experience (QoE) evaluation experiments for the quantification and the perceptual interpretation of the quality achieved during content reproduction. The implemented system was successfully applied in real-world applications, such as the transmission of cultural events from Thessaloniki Concert Hall throughout Greece as well as the reproduction of Philadelphia Orchestra performances (USA) via Internet2 and GEANT backbones.C. E. Vegiris, K. A. Avdelidis, C. A. Dimoulas, and G. V. PapanikolaouCopyright © 2008 C. E. Vegiris et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2008/843270/The convergence of telecommunication, cable TV, and broadcast networks towards the Internet technology will enable the provision of emerging multimedia services as well as the integration of rich communication capabilities with TV services. However, enabling efficient delivery of interactive personalized multimedia services with mobility support requires an advanced overlay control framework. The IP Multimedia Subsystem (IMS) offers the basic functions to manage multimedia sessions over different access networks. This paper outlines current standardization activities that address the provisioning of TV services over IP networks—known as IPTV—and proposes a novel end-to-end overall architecture based on IMS that enables the delivery of converged multimedia services. Furthermore, the paper presents the FOKUS Media Interoperability Lab as a reference implementation of this framework which covers a widespread spectrum of converged interactive scenarios. The final section gives an impression of the system performance by providing the end-to-end signaling delay of a session setup for live TV service delivered over unicast transmission mode.Adel Al-Hezmi, Thomas Magedanz, Jordi Jaen Pallares, and Christian RiedeCopyright © 2008 Adel Al-Hezmi et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2008/319063/Digital TV systems are being deployed worldwide, and interactive applications are being offered as part of the services. The unparalleled success of DVD technology has motivated the development of interactive services for broadcast TV, with DVB-MHP being the most widely used open standard in the world. Despite the similarities between DVB-MHP-based interactive TV and the new Blu-ray format, there still exist substantial differences that make the two systems incompatible. In this paper, we analyze the differences in the DVB-MHP and Blu-ray interactive formats and propose a transcoding scheme to convert live broadcast interactive TV to a Blu-ray compatible format.Sergio Infante and Panos NasiopoulosCopyright © 2008 Sergio Infante and Panos Nasiopoulos. All rights reserved.http://www.hindawi.com/journals/ijdmb/2008/243937/This paper presents a simplified method for signal level clearance evaluation in each place of signal reception up to threshold for a given portable TV receiver device. It describes briefly the structure of transmission system considering the “1Seg” structure of ISDB-T. The preliminary laboratory test was made before the field tests to verify the main features of handheld receiver.Gunnar Bedicks Jr., Fujio Yamada, Francisco Sukys, Cristiano Akamine, Luis Tadeu Raunheitte, and Edson L. HortaCopyright © 2008 Gunnar Bedicks Jr. et al. All rights reserved.http://www.hindawi.com/journals/ijdmb/2008/523649/Multiple transmission of heterogeneous services is a central aspect of broadcasting technology. Often, in this framework, the design of efficient communication systems is complicated by stringent bandwidth constraint. In wavelet packet division multiplexing (WPDM), the message signals are waveform coded onto wavelet packet basis functions. The overlapping nature of such waveforms in both time and frequency allows improving the performance over the commonly used FDM and TDM schemes, while their orthogonality properties permit to extract the message signals by a simple correlator receiver. Furthermore, the scalable structure of WPDM makes it suitable for broadcasting heterogeneous services. This work investigates unequal error protection (UEP) of data which exhibit different sensitivities to channel errors to improve the performance of WPDM for transmission over band-limited channels. To cope with bandwidth constraint, an appropriate distribution of power among waveforms is proposed which is driven by the channel error sensitivities of the carried message signals in case of Gaussian noise. We address this problem by means of the genetic algorithms (GAs), which allow flexible suboptimal solution with reduced complexity. The mean square error (MSE) between the original and the decoded message, ψ which has a strong correlation with subjective perception, is used as an optimization criterion.Maurizio MurroniCopyright © 2008 Maurizio Murroni. All rights reserved.