Improving server broadcast effieciency [i.e. efficiency] by better utilization of client receiving bandwidth

Periodic broadcast is a cost-effective solution for disseminating popular videos. This strategy has the potential to serve a very large community with minimal broadcast bandwidth: regardless of the number of video requests, the worst service latency to all clients is constant. Although many efficient schemes have been proposed, most of them impose some rigid requirement on client receiving bandwidth. They either demand clients to have the same bandwidth as the video server, or limit them to receive no more than two video streams at any one time. In our previous work, we addressed this problem by proposing a Client-Centric Approach (CCA). Unlike any other technique, CCA takes both server broadcast bandwidth and client receiving bandwidth into design consideration. More specifically, CCA allows clients to use all their receiving capability for prefetching broadcast data. Therefore, given a fixed broadcast bandwidth, CCA can achieve shorter broadcast period with an improved client communication capability. In this paper, we present a novel technique to further leverage client bandwidth for more efficient video broadcast. We prove the correctness of this new technique and provide analytical evaluations to show that with the same bandwidth, it achieves significantly better performance than CCA

Single-Channel Data Broadcasting under Small Waiting Latency

Due to the advancement of network technology, video-on-demand (VoD) services are growing in popularity. However, individual stream allocation for client requests easily causes a VoD system overload; when its network and disk bandwidth cannot match client growth. This study thus presents a fundamentally different approach by focusing solely on a class of applications identified as latency tolerant applications. Because video broadcasting does not provide interactive (i.e., VCR) functions, a client is able to tolerate playback latency from a video server. One efficient broadcasting method is periodic broadcasting, which divides a video into smaller segments and broadcasts these segments periodically on multiple channels. However, numerous practical systems, such as digital video broadcasting-handheld (DVB-H), do not allow clients to download video data from multiple channels because clients usually only have one tuner. To resolve this problem in multiple-channel broadcasting, this study proposes a novel single-channel broadcasting scheme, which leverages segment-broadcasting capability further for more efficient video delivery. The comparison results show that, with the same settings of broadcasting bandwidth, the proposed scheme outperforms the alternative broadcasting scheme, the hopping insertion scheme, SingBroad, PAS, and the reverse-order scheduling scheme for the maximal waiting time

Novel Techniques for Large-Scale and Cost-Effective Video Services

Despite the advance of network technologies in the past decade, providing video services to a large number of users remains a major technical challenge. This is especially true when it comes to serving high-definition videos. This thesis makes two contributions towards providing large-scale and cost-effective video services. 1) We consider the problem of periodic broadcast of popular videos in client/server video systems and present two novel techniques. Our research advances the state of the art with a segmentation rule that can generate a series of broadcast designs, among which we can choose the one that results in the smallest broadcast latency. We show that this rule allows us to design the broadcast technique that is the fastest up to date. 2) We then look at the problem of service scheduling in fully distributed peer-to-peer video systems, where a large number of hosts collaborate for the purpose of video sharing. Our proposed technique allows a client to be served by a server that is beyond its own file look up scope and can dynamically adjust client and server matches as new video requests arrive in the system. Our performance evaluation shows that these features dramatically improve the system performance to a large extent in terms of reducing service latency under a range of simulation settings

Protocolos de difusão periodica de video sob limitação de banda passante

Orientador : Nelson Luis Saldanha da FonsecaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Sistemas de Video sob Demanda possibilitam ao usuário a escolha de vídeos para exibiçao dentre uma vasta coleção. Como a transmissão de um fluxo de vídeo demanda uma grande quantidade de bande passante, estratégias de compartilhamento da transmissão de fluxos de vídeo são utilizadas para reduzir esta demanda. Dentre estas técnicas, os protocolos baseados em difusão periódica são indicados para a transmissão dos vídeos mais requisitados, uma vez que estes utilizam largura de banda constante independente do número de usuários. Entretanto, os protocolos mais eficientes nao levam em consideração limitações de banda passante existentes no cliente. Nesta dissertação, dois protocolos de difusão periódica otimamente estruturados são estendidos de forma a permitir que clientes sujeitos a limitações de largura de banda possam utilizar serviços de Vídeo sob Demanda baseados em difusão periódicaAbstract: Video on Demand (VoD) services allow users to watch movies of their choice among a wide collection. As video transmition requires a huge amount of bandwidth, stream sharing techniques has been developed to reduce the bandwidth requirements. Among these techniques, periodic broadcasting protocols are indicated to transmit most frequently requested videos, since they require a constant amount of bandwidth. However, these protocolos do not consider users with limited bandwidth. In this dissertation two new protocols are introduced, the Polyharmonic Broadcasting with Limited User Bandwidth (PHB-LUB) and the Greedy Equal-Bandwidth Broadcasting with Limited User Bandwidth (GEBB-LUB)MestradoCiência da ComputaçãoMestre em Ciência da Computaçã

Design, analysis, and experimental verification of continuous media retrieval and caching strategies for network-based multimedia services

Ph.DDOCTOR OF PHILOSOPH

Enhanced Rateless Coding and Compressive Sensing for Efficient Data/multimedia Transmission and Storage in Ad-hoc and Sensor Networks

In this dissertation, we investigate the theory and applications of the novel class of FEC codes called rateless or fountain codes in video transmission and wireless sensor networks (WSN). First, we investigate the rateless codes in intermediate region where the number of received encoded symbols is less that minimum required for full datablock decoding. We devise techniques to improve the input symbol recovery rate when the erasure rate is unknown, and also for the case where an estimate of the channel erasure rate is available. Further, we design unequal error protection (UEP) rateless codes for distributed data collection of data blocks of unequal lengths, where two encoders send their rateless coded output symbols to a destination through a common relay. We design such distributed rateless codes, and jointly optimize rateless coding parameters at each nodes and relaying parameters. Moreover, we investigate the performance of rateless codes with finite block length in the presence of feedback channel. We propose a smart feedback generation technique that greatly improves the performance of rateless codes when data block is finite. Moreover, we investigate the applications of UEP-rateless codes in video transmission systems. Next, we study the optimal cross-layer design of a video transmission system with rateless coding at application layer and fixed-rate coding (RCPC coding) at physical layer. Finally, we review the emerging compressive sensing (CS) techniques that have close connections to FEC coding theory, and designed an efficient data storage algorithm for WSNs employing CS referred to by CStorage. First, we propose to employ probabilistic broadcasting (PB) to form one CS measurement at each node and design CStorage- P. Later, we can query any arbitrary small subset of nodes and recover all sensors reading. Next, we design a novel parameterless and more efficient data dissemination algorithm that uses two-hop neighbor information referred to alternating branches (AB).We replace PB with AB and design CStorage-B, which results in a lower number of transmissions compared to CStorage-P.Electrical Engineerin