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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

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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.

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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.

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Fast broadcasting scheme(FB)

In FB scheme, we divide a movie into 2k - 1 segments, k channels is needed.

Waiting time: = D / 7 ( D: the video length )

S1

S2

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bChannel 1

Channel 2

Channel 3

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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

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Channel transition for the FB scheme Data padding

We pad some dummy data at the end of V

FB: the number of segments: 2k – 1

(K: the number of assigned channels)

Channel Transition: the number of segments: 2k

(the last 2k-2 segments are dummy segments)

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Correspondence relation Correspondence relation

|Vdummy| = D / (2 - 1) D: movie length

The total number of broadcasting channels

The No. of segments

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FB Broadcasting scheme s is the video content broadcast on c

hannel Cd 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

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FB Broadcasting scheme

K = 2

K = 3

K = 4

= cycle( )

= cycle( )

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Channel transition broadcasting scheme s is obtained from by cyclically

shifting the latter’s video segments to the right by 2k-2 – 1 time slot

k: the total number of broadcasting channels

d: the No. of channels

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Channel transition broadcasting scheme

K = 2

K = 3

K = 4

0, ))

2k-2 – 1 = 22-2 – 1 = -1 0

1, ))

2k-2 – 1 = 23-2 – 1 = 1

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FB vs. channel transition broadcasting scheme

FB Channel transition

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Channel transition example (Upgrade K from 2 3 )

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Upgrade K from 2 3 (case 1)

The gray segments are what a client should download before and after the transition

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Upgrade K from 2 3 (case 2)

The gray segments are what a client should download before and after the transition

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Upgrade theorem Theorem: for any segment j

d = 1

d’ = d +1 = 2

d = 1

d’ = d = 1d’ = d + 1 = 2

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DowngradeThe time to make a change

U4 – U3 = { , , }

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Downgrade (from 4 2)

U3 – U2

U4 – U3These two channels will be released when their content has finished broadcasting

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Comparisons

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Comparisons

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Comparisons