A double patching technique for efficient bandwidth sharing in video-on-demand systems
A double patching technique for efficient bandwidth sharing in video-on-demand systems
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DOI：
10.1007/s11042-006-0049-8
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发表时间：
2006
影响因子：
3.6
通讯作者：
Ying Cai;Wallapak Tavanapong;K. Hua
中科院分区：
文献类型：
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作者：
Ying Cai;Wallapak Tavanapong;K. Hua
补丁是视频点播系统中一种有效的带宽共享技术。在这种环境中，客户端加入正在进行的常规多播以接收数据并将其缓存在本地缓冲区中。服务器只需要在修补流中发送视频的前导部分。当客户端完成回放修补数据时，它使用已经缓存在缓冲区中的数据继续回放。虽然这种策略可以在没有服务延迟的情况下实现流共享，但Patching的性能有局限性：随着到最后一个常规组播的时间距离的增加，新请求的修补成本增加，最终，必须调度新的常规组播来平衡成本。在本文中，我们解决这个问题，提出了一种新的技术，称为双修补。我们的研究是基于这样的观察，即如果修补流提供额外的2 ·wptime单元的视频数据，则它可以被下一个wptime单元中到达的视频请求共享。有了这些额外的数据，这些请求的修补成本可以大大降低。在新技术中，客户端在任何时候使用不超过两个下载通道。因此，其实施成本与原始修补程序相同。至于其性能，我们的研究表明，所提出的技术实现的改进是显着的。在许多情况下，“双重修补”的性能是原始“修补”的两倍。
Patching is an efficient bandwidth-sharing technique for video-on-demand systems. In this environment, a client joins an on-going regular multicast to receive and cache the data in a local buffer. The server needs to send only the leading portion of the video in a patching stream. When the client finishes playing back the patching data, it continues the playback using the data already cached in the buffer. Although this strategy enables stream sharing without the service delay, the performance of Patching has limitation: as the time distance to the last regular multicast enlarges, the patching cost for new requests increases and eventually, a new regular multicast must be scheduled to balance the cost. In this paper, we address this problem by proposing a new technique calledDouble Patching. Our research is based on the observation that a patching stream can be shared by the video requests arriving in the nextwptime units if it delivers an additional 2 ·wptime units of video data. With these extra data, the patching cost for these requests can be dramatically reduced. In the new technique, a client uses no more than two download channels at any one time. Thus, its implementation cost is the same as that of the original Patching. As for its performance, our study shows that the improvement achieved by the proposed technique is significant. In many cases, Double Patching doubles the performance of the original Patching.