Recent years have witnessed an explosive growth in mobile video-based services and efficient and reliable video delivery draws more and more attention. As a type of rateless codes, fountain codes can automatically ada...Recent years have witnessed an explosive growth in mobile video-based services and efficient and reliable video delivery draws more and more attention. As a type of rateless codes, fountain codes can automatically adapt to wireless channel conditions with- out any knowledge of channels. This paper provides an overview of several typical Foi-ward Error Correction （FEC） codes, such as Reed-Solomon （RS） code, Tornado code, Luby-Transform （LT） code, and Raptor code. We focus on a novel delay-aware fountain coding （DAF） technique that maxinfizes the code word length under the constraint of a given delay. Based on DAF, this paper also presents Unequal Error Protection DAF （UEP-DAF） which improves the Peak Signal to Noise Ratio （PSNR） without additional co- ordination between the encoder and the decoder, as well as Model Predictive Control DAF （MPC-DAF） which reduces the compu- tational complexity to an affordable level for real-time video comnmnications. Moreover, we review- video streaming technologies, then introduce Dynamic Adaptive Streaming over HTTP （DASH） and DASH over Multiple Content Distribution Servers （MCDS- DASH） in detail. Based on MCDS-DASH that adapts video bitrate at the block level to alleviate video fluctuation, we propose a novel approach to integrating fountain codes with MCDS-DASH, which is capable of achieving unprecedented high throughput.展开更多
The increasing popularity of smart mobile devices and the rise of online services has increased the requirements for efficient dissemination of social video contents. In this paper,we study the problem of distributing...The increasing popularity of smart mobile devices and the rise of online services has increased the requirements for efficient dissemination of social video contents. In this paper,we study the problem of distributing video from cloud server to users in partially connected cooperative D2 D network using network coding. In such a scenario, the transmission conflicts occur from simultaneous transmissions of multiple devices, and the scheduling decision should be made not only on the encoded packets but also on the set of transmitting devices. We analyze the lower bound and give an integer linear formulation of the joint optimization problem over the set of transmitting devices and the packet combinations.We also propose a heuristic solution for this setup using a conflict graph and local graph at every device. Simulation results show that our coding scheme significantly reduces the number of transmission slots, which will increase the efficiency of video delivery.展开更多
With relatively high transmission capacity and usually unconstrained connections, IEEE802.11 WLANs provide the ideal infrastructure for pervasive video content sharing and communications. However, the delivery of high...With relatively high transmission capacity and usually unconstrained connections, IEEE802.11 WLANs provide the ideal infrastructure for pervasive video content sharing and communications. However, the delivery of high-performance video streams over 802.11 WLANs remains a challenging task due to the inherent characteristics of compressed video and dynamic channels. In this paper, we present a brief survey of various recent innovations that have been developed to enhance the Quality of Service (QoS) performance for video over WLANs. Based on the application scenarios, the solutions have focused mainly on three network layers, that is, Application layer (APP), Media Access Control layer (MAC), and Physical layer (PHY). After reviewing the video compression technology, we first examine various single-layer solutions for video over WLANs. We then discuss several cross-layer solutions that take advantage of mutual interactions between different network layers. Finally, several technical issues beyond QoS performance, including energy and security, are also addressed. We conclude that the application of video over WLANs will continue to increase in future.展开更多
The emergence of smart edge-network content item hotspots, which are equipped with huge storage space （e.g., several GBs）, opens up the opportunity to study the possibility of delivering videos at the edge network. ...The emergence of smart edge-network content item hotspots, which are equipped with huge storage space （e.g., several GBs）, opens up the opportunity to study the possibility of delivering videos at the edge network. Different from both the conventional content item delivery network （CDN） and the peer-to-peer （P2P） scheme, this new delivery paradigm, namely edge video CDN, requires up to millions of edge hotspots located at users＇ homes/offices to be coordinately managed to serve mobile video content item. Specifically, two challenges are involved in building edge video CDN, including how edge content item hotspots should be organized to serve users, and how content items should be replicated to them at different locations to serve users. To address these challenges, we propose our data-driven design as follows. First, we formulate an edge region partition problem to jointly maximize the quality experienced by users and minimize the replication cost, which is NP-hard in nature, and we design a Voronoi-like partition algorithm to generate optimal service cells. Second, to replicate content items to edge-network content item hotspots, we propose an edge request prediction based replication strategy, which carries out the replication in a server peak offioading manner. We implement our design and use trace-driven experiments to verify its effectiveness. Compared with conventional centralized CDN and popularity-based replication, our design can significantly improve users＇ quality of experience, in terms of users＇ perceived bandwidth and latency, up to 40%.展开更多
文摘Recent years have witnessed an explosive growth in mobile video-based services and efficient and reliable video delivery draws more and more attention. As a type of rateless codes, fountain codes can automatically adapt to wireless channel conditions with- out any knowledge of channels. This paper provides an overview of several typical Foi-ward Error Correction （FEC） codes, such as Reed-Solomon （RS） code, Tornado code, Luby-Transform （LT） code, and Raptor code. We focus on a novel delay-aware fountain coding （DAF） technique that maxinfizes the code word length under the constraint of a given delay. Based on DAF, this paper also presents Unequal Error Protection DAF （UEP-DAF） which improves the Peak Signal to Noise Ratio （PSNR） without additional co- ordination between the encoder and the decoder, as well as Model Predictive Control DAF （MPC-DAF） which reduces the compu- tational complexity to an affordable level for real-time video comnmnications. Moreover, we review- video streaming technologies, then introduce Dynamic Adaptive Streaming over HTTP （DASH） and DASH over Multiple Content Distribution Servers （MCDS- DASH） in detail. Based on MCDS-DASH that adapts video bitrate at the block level to alleviate video fluctuation, we propose a novel approach to integrating fountain codes with MCDS-DASH, which is capable of achieving unprecedented high throughput.
基金supported by Fundamental Research Funds for the Central Universities(No.SWU115002,No.XDJK2015C104)
文摘The increasing popularity of smart mobile devices and the rise of online services has increased the requirements for efficient dissemination of social video contents. In this paper,we study the problem of distributing video from cloud server to users in partially connected cooperative D2 D network using network coding. In such a scenario, the transmission conflicts occur from simultaneous transmissions of multiple devices, and the scheduling decision should be made not only on the encoded packets but also on the set of transmitting devices. We analyze the lower bound and give an integer linear formulation of the joint optimization problem over the set of transmitting devices and the packet combinations.We also propose a heuristic solution for this setup using a conflict graph and local graph at every device. Simulation results show that our coding scheme significantly reduces the number of transmission slots, which will increase the efficiency of video delivery.
文摘With relatively high transmission capacity and usually unconstrained connections, IEEE802.11 WLANs provide the ideal infrastructure for pervasive video content sharing and communications. However, the delivery of high-performance video streams over 802.11 WLANs remains a challenging task due to the inherent characteristics of compressed video and dynamic channels. In this paper, we present a brief survey of various recent innovations that have been developed to enhance the Quality of Service (QoS) performance for video over WLANs. Based on the application scenarios, the solutions have focused mainly on three network layers, that is, Application layer (APP), Media Access Control layer (MAC), and Physical layer (PHY). After reviewing the video compression technology, we first examine various single-layer solutions for video over WLANs. We then discuss several cross-layer solutions that take advantage of mutual interactions between different network layers. Finally, several technical issues beyond QoS performance, including energy and security, are also addressed. We conclude that the application of video over WLANs will continue to increase in future.
基金This work was supported by the National Basic Research 973 Program of China under Grant No. 2015CB352300, the National Natural Science Foundation of China under Grant Nos. 61402247, 61272231, and 61133008, and the Beijing Key Laboratory of Net- worked Multimedia.
文摘The emergence of smart edge-network content item hotspots, which are equipped with huge storage space （e.g., several GBs）, opens up the opportunity to study the possibility of delivering videos at the edge network. Different from both the conventional content item delivery network （CDN） and the peer-to-peer （P2P） scheme, this new delivery paradigm, namely edge video CDN, requires up to millions of edge hotspots located at users＇ homes/offices to be coordinately managed to serve mobile video content item. Specifically, two challenges are involved in building edge video CDN, including how edge content item hotspots should be organized to serve users, and how content items should be replicated to them at different locations to serve users. To address these challenges, we propose our data-driven design as follows. First, we formulate an edge region partition problem to jointly maximize the quality experienced by users and minimize the replication cost, which is NP-hard in nature, and we design a Voronoi-like partition algorithm to generate optimal service cells. Second, to replicate content items to edge-network content item hotspots, we propose an edge request prediction based replication strategy, which carries out the replication in a server peak offioading manner. We implement our design and use trace-driven experiments to verify its effectiveness. Compared with conventional centralized CDN and popularity-based replication, our design can significantly improve users＇ quality of experience, in terms of users＇ perceived bandwidth and latency, up to 40%.
