A LARGE-SCALE MULTIPLE-ACCESS METHOD FOR VIDEO-ON-DEMAND SYSTEMS

A multiple-access method is proposed for simultaneously providing video data to more than 100 terminals in a video-on-demand system. The proposed method divides up each video program into segments, stores the segments on multiple disk drives, and performs time-division-multiplex reading based on the time-slot sequences for each dish drive that are periodically phase shifted with respect to each other, This method features: 1) theoretical limit on the maximum number of multiple accesses that can be implemented, and straightforward upscaling of the maximum number of multiple accesses because the amount of buffer memory needed for each terminalis fixed; 2) no request loss, even when many terminals request the same program because the load for reading each video program is always distributed across all the disk drives; and 3) system control that guarantees read-request response times within a specified value by allowing the skipping of a very small amount of leading information in each video program. Numerical examples show that this access method makes it possible to design a system having no request losses and a guaranteed response time within one second, even for simultaneous accesses by 900 terminals.