Harmonic Block Windows Scheduling Through Harmonic Windows Scheduling
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چکیده
Broadcasting offers a bandwidth-efficient way of delivering popular content in media-on-demand (MoD) systems. Harmonic windows scheduling (HWS) is a mathematical framework that is relevant to bandwidth minimization in MoD broadcasting. Given c channels, the optimal HWS problem tries to schedule as many pages of a video as possible in the c channels. Let κ be the largest integer n satisfying Hn ≤ c, where Hn is the n th harmonic number. Then κ is an upper bound on the number of pages that can be scheduled in c channels, if the HWS framework is used. Thus bandwidth of at least c −Hκ is wasted. We have recently generalized HWS to harmonic block windows scheduling (HBWS), which can overcome this limitation inherent in HWS. It divides each page into a set of β equal sized fragments, thus providing a way of scheduling fragments of the same page at different periods. We propose a method that starts with a round-robin tree representing a HWS schedule and improves it to generate a HBWS schedule that achieves a higher ratio N/β, where N is the number of fragments scheduled. For up to six channels, we show that we can always achieve N/β > κ. We also demonstrate that as we increase β, N/β approaches the theoretical upper bound.
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تاریخ انتشار 2005