Hierarchical video patching with optimal server bandwidth

Abstract

Video patching is a way for transporting true video-on-demand, that is, instantaneous without any delay, from a video server to several clients. Instead of sending a unique stream to each newly arriving client, clients share as many multicast transmissions as possible, and are serviced only those parts of the video that they have missed.We present a novel video patching scheme using hierarchies of patches. Our scheme minimizes the bandwidth needed by the video server, and may result in the fact that clients receive several streams in parallel. We show analytically that for Poisson arrival our algorithm achieves the optimal possible server bandwidth for all schemes where clients share multicast transmissions.We also show, how our approach can be combined with batching. This combination requires less server bandwidth than all fixed start point periodic broadcast algorithms.

Hybrid multicast-unicast streaming over mobile networks

“…Patching methods allow receivers to immediately join an existing multicast session, while the missed portions are transmitted via temporary unicast connections [21,18,7]. It requires that the receiver receives video from both unicast and multicast sessions concurrently and buffers the video from the multicast session [21].…”

“…It requires that the receiver receives video from both unicast and multicast sessions concurrently and buffers the video from the multicast session [21]. Since, the receiver can start playback of the video immediately from the unicast session, it does not cause any additional start-up delay.…”

“…We consider an allocation window with T columns of symbols and S rows of subchannels as shown in Figure 3 [21,18,7] can be adopted. A threshold can be used for a new request to join an on-going multicast session of video and at the same time a temporary unicast session is created to serve the earlier segments of the video to the requesting mobile user.…”

“…The figure shows that the experienced service delay for the admitted mobile users on average is less than 6 seconds which is slightly over half of the length of the allocation window. If a shorter delay is required for any mobile users, a patching technique [21,18,7] may be employed for them to achieve the targeted delay. In patching, the system allows incoming users to immediately join ongoing multicast sessions, and the missed portions of the video are transmitted using temporary unicast connections.…”

Optimal server bandwidth for mobile video on demand

“…The result is a true-VoD transmission scheme we call Hierarchical Patching [16], which provably uses the minimum server bandwidth. Additionally, its batched version provably uses less bandwidth than any fixed-start broadcasting scheme with equal waiting time.…”