A NEW VOD TECHNIQUE TO SUPPORT CLIENT MOBILITY

Abstract

This paper introduces fragmented patching, a new video on-demand technique that enables mobile clients to receive a video stream while moving freely. Patching techniques that significantly reduce the required network bandwidth through multicasting have shown potential for on-demand video distribution. However, patch-flow techniques based on unicast data are unsuitable for providing services to mobile clients because an intricate form of mobile routing is needed for each unicast flow to enable it to individually follow a moving client. Conversely, in fragmented patching, patch flows are sent via broadcasting. The patch flows are divided into segments to avoid increasing traffic due to broadcasting; each of the segments is aggregated to be shared with as many clients as possible. In addition, we have considered broadcasting shared flows also to eliminate any overhead arising from multicast tree construction. This paper analyzes the network bandwidth required for fragmented patching for two cases: when the patch flow is broadcast and the shared flow is multicast, and when both the patch and shared flows are broadcast. Numerical analysis based on the traffic intensity (Erlang) has revealed that the aggregation effect caused by segmenting patch flows counteracts the increase in traffic caused by broadcasting. It also showed that fragmented patching reduces the required bandwidth by a greater extent than other patching techniques even when both the patch and shared flows are broadcast.