Current Issue : July - September Volume : 2015 Issue Number : 3 Articles : 5 Articles
IPTV services are typically featured with a longer channel changing delay compared to the conventional TV systems. The major\ncontributor to this lies in the time spent on intraframe (I-frame) acquisition during channel changing. Currently, most widely\nadopted fast channel changing (FCC) methods rely on promptly transmitting to the client (conducting the channel changing)\na retained I-frame of the targeted channel as a separate unicasting stream. However, this I-frame acceleration mechanism has\nan inherent scalability problem due to the explosions of channel changing requests during commercial breaks. In this paper, we\npropose a fairness-based admission control (FAC) scheme for the original I-frame acceleration mechanism to enhance its scalability\nby decreasing the bandwidth demands. Based on the channel changing history of every client, the FAC scheme can intelligently\ndecide whether or not to conduct the I-frame acceleration for each channel change request. Comprehensive simulation experiments\ndemonstrate the potential of our proposed FACscheme to effectively optimize the scalability of the I-frame acceleration mechanism,\nparticularly in commercial breaks. Meanwhile, the FAC scheme only slightly increases the average channel changing delay by\ntemporarily disabling FCC (i.e., I-frame acceleration) for the clients who are addicted to frequent channel zapping....
Vehicular ad hoc network (VANET) has gained much attention recently to improve road safety, reduce traffic congestion, and\nenable efficient traffic management because of its many important applications in transportation. In this paper, an early warning\nintelligence broadcasting algorithmis proposed, EW-ICAST, to disseminate a safety message forVANETs.Theproposed EW-ICAST\nuses not only the early warning system on the basis of time to collision (TTC) but also the intelligent broadcasting algorithm on\nthe basis of fuzzy logic. Thus, the EW-ICAST resolves effectively broadcast storm problem and meets time-critical requirement.\nThe performance of EW-ICAST is evaluated through simulation and compared with that of other alert message dissemination\nalgorithms. From the simulation results, we know that EW-ICAST is superior to Simple, P-persistence, and EDB algorithms....
Mobile IPTV services over wireless cellular networks become more and more popular, owing to the significant growth in access\nbandwidth of wireless cellular networks such as 3G/4G andWiMAX.However, the spectrumresources of wireless cellular networks\nis rare. How to enhance the spectral efficiency of mobile networks becomes an important issue. Unicast, broadcast, and multicast\nare the most important transport schemes for offering mobile IPTV services over wireless cellular networks. Therefore, bandwidth\nusages and blocking rates of unicast, broadcast, andmulticast IPTV services were analyzed and compared in this paper. Simulations\nwere also conducted to validate the analytical results. Numerical results demonstrate that the presented analysis is correct, and\nmulticast scheme achieves the best bandwidth usage and blocking rate performance, relative to the other two schemes....
With the rapid development of P2P technology, P2P IPTV applications have received more and more attention. And program\nresource distribution is very important to P2P IPTV applications. In order to collect IPTV program resources, a distributed multiprotocol\ncrawler is proposed. And the crawler has collected more than 13 million pieces of information of IPTV programs from\n2009 to 2012. In addition, the distribution of IPTV programs is independent and incompact, resulting in chaos of program names,\nwhich obstructs searching and organizing programs.Thus, we focus on characteristic analysis of program resources, including the\ndistributions of length of programnames, the entropy of the character types, and hierarchy depth of programs. These analyses reveal\nthe disorderly naming conventions of P2P IPTV programs.The analysis results can help to purify and extract useful information\nfromchaotic names for better retrieval and accelerate automatic sorting of programand establishment of IPTV repository. In order\nto represent popularity of programs and to predict user behavior and popularity of hot programs over a period,we also put forward\nan analytical model of hot programs....
In practical unlicensed communications in TV band, radio devices have to identify, at first, the transmission opportunities, that\nis, the portion of the spectrum licensed for broadcasting services unoccupied in a certain region at certain time, that is, the socalled\nTV white space. In this paper the outcome of field measurements in the UHF TV band (470ââ?¬â??860MHz) conducted in EU\nis presented. To obtain empirical values for the parameters upon which unlicensed radio devices are able to distinguish in a real\nscenario between empty and occupied TV channels, signal powermeasurements have been performed in Italy, Spain, and Romania\non rural, suburban, and urban sites, at different heights over the ground by using different analysis bandwidths.Theaimof this work\nis to provide a set of practical parameters upon which harmless unlicensed communication in the UHF TV white space is feasible.\nThe results have been analyzed with respect to the hidden node margin problem, spectrum sensing bandwidth, and occupancy\nthreshold....
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