Techniques for improving the capacity of video-on-demand systems

We present two techniques to improve the capacity of video on demand systems. Video on demand is an electronic video rental system in which clients request and play videos on-demand. Video on demand system can be implemented over an existing cable TV network or an upgraded ADSL network. The two techniques used to improve the capacity of video on-demand systems are segmentation and multicasting. Segmentation consists of dividing the video into several fixed length segments, and then transmitting the segments at regular intervals instead of transmitting the entire video continuously. Multicasting assumes that each subscriber has a limited storage space, so the same video segments can be multicast to subscribers simultaneously. Results of a comprehensive simulation study presented in the paper show a significant improvement in the capacity of the system when these two techniques are applied. In evaluating video on demand systems we considered the following parameters: the number of users supported, the number of videos played per day, and the number of requests rejected per day.