Analysis of Patching Scheme from a Practical Perspective

Most previous researches on patching scheme mainly focused on efficient patch stream generation to minimize the required bandwidth by proposing the optimum patching window. Another typical aspect is that they assumed that all the streaming speed is playback speed without deeply analyzing the effects of streaming speed. However, higher streaming speed, especially higher multicast streaming speed, may give better results in some aspects. Therefore, in this study, we analyze the effects of multicast streaming speed in the aspect of bandwidth usage, when VCR function is supported. First, we reanalyze the previous optimum patching window and total required bandwidth of the patching scheme, since the previous result is too approximate and give inaccurate results in some cases. So, we propose a modified optimum patching window to generate more accurate results when the speed of multicast streams is playback speed. Second, we calculate the optimum patching window and required bandwidth when the multicast streaming speed is multiple times the playback speed. The result shows that optimum patching window size reduces and required bandwidth increases when the speed of multicast stream increases. Finally, we show that the performance patching scheme degrades when VCR action is generated. The playback speed streaming of multicast streams gives good performance in bandwidth usage if VCR function is not considered. However, our analysis shows that the required bandwidth sharply increases when we consider VCR function support. The streaming speed of the multicast stream, which is equal to fast search (FS) streaming speed, gives the upper bound for the required bandwidth when FS function is considered.