Piecewise Patching for Time-shifted TV Over HFC Networks

In video-on-demand (VOD) systems, a number of sophisticated architectures have been proposed to provide instantaneous services through the use of multicast technology. Most of the architectures focus on minimizing bandwidth requirements under the assumption that clients play from beginning to end, but this assumption is not suitable for time-shifted TV. Moreover, they have been proposed on an IP network, and failed to make full use of the broadcasting property of hybrid fiber coaxial (HFC) network. In this paper, we propose a novel delivery scheme, named as piecewise patching (PP), to tackle these problems. The piecewise patching scheme provides the video data for the users in a piecewise mode instead of a whole patching stream which includes all missing data. The former user can utilize the data from the later users´ patching stream whose playback time is in advance of the former user´s patching stream. In the proposed scheme, each client receives the data simultaneously from arbitrary channels which broadcast the same content. Simulation results show that the proposed scheme improves the performance of time-shift TV service significantly in terms of total server bandwidth requirement.