1 Data Broadcasting and Seamless Channel Transition for Highly Demanded Videos Yu-Chee Tseng, Ming-Hour Yang, Chi-Ming Hsieh, Wen-Hwa Liao, and Jang-Ping IEEE Transactions on Communications

2 Outline Fast broadcasting scheme (FB) A novel seamless channel transition enhancement on top of the FB scheme to dynamically change the number of channels assigned to a video on-the-fly.

3 Introduction One way to broadcast a popular video is to use a number of dedicated channels, each responsible for broadcasting some portion of the video periodically in a predefined way. One such scheme is the fast broadcasting(FB) scheme.

4 Fast broadcasting scheme(FB) In FB scheme, we divide a movie into 2 k - 1 segments, k channels is needed. Waiting time:  = D / 7 ( D: the video length ) S1 S2 S4 S1 S3 S5 S1 S2 S6 S1 S3 S7 S1 S2 S4 S1 S3 S5 S1 S2 S6 S1 S3 S7  b Channel 1 Channel 2 Channel 3

5 Problems of FB scheme The number of channels assigned to the video is fixed However, the level of demand on the video may change by time, it is desirable that the number of channels assigned to the video can adapt to such changes, we call this channel transition when the video is undergoing some change on the number of channels used

6 Channel transition for the FB scheme Data padding We pad some dummy data at the end of V FB: the number of segments: 2 k – 1 (K: the number of assigned channels) Channel Transition: the number of segments: 2 k (the last 2 k-2 segments are dummy segments)

7 Correspondence relation |V dummy | = D / (2  - 1) D: movie length The total number of broadcasting channels The No. of segments

8 FB Broadcasting scheme s is the video content broadcast on channel C d by our modified FB scheme, where cycle(s) means an infinite repetition of the given video stream s k: the total number of broadcasting channels d: the No. of channels

9 FB Broadcasting scheme K = 2 K = 3 K = 4 = cycle( ) = cycle(  )

10 Channel transition broadcasting scheme s is obtained from by cyclically shifting the latter ’ s video segments to the right by 2 k-2 – 1 time slot k: the total number of broadcasting channels d: the No. of channels

11 Channel transition broadcasting scheme K = 2 K = 3 K = 4 0,  )) 2 k-2 – 1 = – 1 = -1  0 1,  )) 2 k-2 – 1 = – 1 = 1

12 FB vs. channel transition broadcasting scheme FBChannel transition

13 Channel transition example (Upgrade K from 2  3 )

14 Upgrade K from 2  3 (case 1) The gray segments are what a client should download before and after the transition

15 Upgrade K from 2  3 (case 2) The gray segments are what a client should download before and after the transition

16 Upgrade theorem Theorem: for any segment j d = 1 d ’ = d +1 = 2 d = 1 d ’ = d = 1 d ’ = d + 1 = 2

17 Downgrade The time to make a change U 4 – U 3 = {,, }

18 Downgrade (from 4  2) U 3 – U 2 U 4 – U 3 These two channels will be released when their content has finished broadcasting

19 Comparisons

20 Comparisons

21 Comparisons