Slotted stream tapping

Video on Demand VOD is a multimedia service which allows a remote user to select and then view video at his convenience at any time he wants. Required bandwidth and latency time, defined as a user maximum waiting time, are usually among the most critical issues in VoD systems. Previous works in the field may be classified within two categories of protocols; namely reactive and proactive. Proactive protocols broadcast video regardless of the number of participating viewers. Reactive protocols, however, broadcast any given video upon the request by at least one client. While the former save bandwidth at high workloads, the later save bandwidth at low workloads. In this paper, we propose a rather hybrid solution, termed Slotted Stream Tapping SST broadcasting protocol, which operates as a reactive protocol at low workloads and as a proactive one at high workloads. We start with a description of our proposed protocol and then provide an exact analytical study of its keys parameters and performance measures. We show that under all different workloads, our SST protocols requires indeed less bandwidth than even the optimal Stream Tapping reactive protocol, performs much better than many well known proactive protocols and assures at high workloads a very reasonable performance with respect to the optimal proactive protocol; namely the Harmonic Broadcasting protocol, yet very easy to implement.