Delay characterization of the MCNS DOCSIS CATV protocol

The Multimedia cable networks system (MCNS) Data over cable service interface specification (DOCSIS) is established as the primary cable network data communications standard. The headend scheduling algorithm is not defined within the standard but it is the key function for providing the required performance capability. We introduce a simple model for minislots allocation, which is a variant of buffered leaky bucket. First come first served (FCFS) discipline is adopted in the model to allocate data minislots. Two simple Contention minislots allocation methods are introduced. Based on these, the average delay is analyzed theoretically. Finally numerical results are presented. Results show that the average delay is closely associated with the distribution of the contention minislots (CMSs) and the number of the CMSs. This provides a reference for complicated scheduling discipline.