Minimizing the Worst-Case Playback Delay in VoD Services over Passive Optical Networks

Minimizing the worst-case playback delay (WPD) in VoD services is both critical and challenging. Given a fixed amount of bandwidth for broadcasting and patching, there is no prior work on determining the minimum WPD, let alone guaranteeing it. In this work, we propose novel schemes that leverage the unique properties of a TDM-based Passive Optical Network (PON) by performing rebroadcasting and patching at its Optical Network Unit (ONUs). For a given bandwidth available for VoD services in the PON, we derive the minimum worst-case playback delay (WPD), and also design optimal patch scheduling algorithm as well as ONU rebroadcast and patching channel assignment to guarantee such minimum WPD. Numerical results confirm the superiority of the proposed schemes over the existing ones in terms of both worst-case and average performance.