VOD节目线程的幂级分配广播方案

Power series distrbution and transmission of VOD programs

在传统的ＶＯＤ广播中，如果希望每１０分钟得到一次收看一部１２０分钟影片的机会，需要１２个视频频道。假设客户端能够在硬盘上缓存影片的某些部分，金字塔广播方案能够将带宽缩减到５７个频道。幂级分配广播方案则仅需要４个频道，对于长度为Ｄ分钟的影片，如果想要将观看者的等待时间缩减到Ｄ／Ｍ分钟，仅需要安排Ｎ（Ｍ）个视频频道来循环广播该影片，其中Ｎ（Ｍ）＝ｌｏｇ２（Ｍ＋１），此方案大幅减少了单个视频点播服务的占用带宽，并在客户端与传统的广播方式兼容。

In conventional VOD transmission,1 2 channels are needed for the delivery of 120-minute movie at every 10 minutes. If some portion of the movie can be buffered by the user's hard disk,the required bandwidth can be reduced to 5.7 channels by means of the pyramid transmission scheme. The power series distribution scheme described in this paper needs only 4 channels,For a movie with length D minutes,if it is desired to reduce the waiting time to D/M minutes,only N(M) ,channels are needs for cyclic transmission of the movie,where N(M) =log 2 (M+1) . The bandwidth required for VOD service per movie is greatly reduced. Further more,the new scheme is compatible with conventional transmission at the user end.