A General Buffer Scheme for the Windows Scheduling Problem

Broadcasting is an efficient alternative to unicast for delivering popular on-demand media requests. Broadcasting schemes that are based on windows scheduling algorithms provide a way to satisfy all requests with both low bandwidth and low latency. Consider a system of n pages that need to be scheduled (transmitted) on identical channels an infinite number of times. Time is slotted, and it takes one time slot to transmit each page. In the windows scheduling problem (WS) each page i, 1 ≤ i ≤ n, is associated with a request window wi. In a feasible schedule for WS, page i must be scheduled at least once in any window of wi time slots. The objective function is to minimize the number of channels required to schedule all the pages. The main contribution of this paper is the design of a general buffer scheme for the windows scheduling problem such that any algorithm for WS follows this scheme. As a result, this scheme can serve as a tool to analyze and/or exhaust all possible WS-algorithms. The buffer scheme is based on modelling the system as a nondeterministic finite state machine in which any directed cycle corresponds to a legal schedule and vice-versa. Since WS is NP-hard, w

Generalized Fibonacci broadcasting: An efficient VOD scheme with user bandwidth limit

AbstractBroadcasting is attractive in delivering popular videos in video-on-demand service, because the server broadcast bandwidth is independent of the number of users. However, the required server bandwidth does depend on how much bandwidth each user can use, as well as on the user's initial waiting time. This paper addresses the issue of limiting the user bandwidth, and proposes a new broadcasting scheme, named Generalized Fibonacci Broadcasting (GFB). In terms of many performance graphs, we show that, for any given combination of the server bandwidth and user bandwidth, GFB can achieve the least waiting time among all the currently known fixed-delay broadcasting schemes. Furthermore, it is very easy to implement GFB. We also demonstrate that there is a trade-off between the user waiting time and the buffer requirement at the user