On zap time minimization in IPTV networks

Digital television systems have a clear disadvantage relative to analog systems in users´ quality of experience, most notably in the time required to change channels, or zap time. The goal of this research is to improve the performance of a multicasting IPTV network, both in user experience and in resource consumption. We formulate the problem of assigning IPTV clients to servers as an integer programming model, in variants which minimize channel-change times, overall network capacity consumption, or both. This problem is shown to be computationally hard, and the performance of the models is tested on problems of different sizes. Polynomial-time heuristics are presented which address a relaxed version of the problem, and the performance of these heuristics is measured.