Reducing energy consumption in IPTV networks by selective pre-joining of channels

Abstract

IPTV services are the fastest growing television services in the world today. This is a bandwidth intensive service, requiring low latency and tight control of jitter. To guarantee the quality of service required, service providers opt to multicast all TV channels at all times to everywhere. However, a significant number of channels are rarely watched, so this method is provably resource- and energy-inefficient. In this paper, we argue that the expected increase in quantity and quality of TV channels will become a serious issue, both in terms of bandwidth and energy costs. To overcome this problem, we propose a dynamic scheme that pre-joins only a selection of TV channels. This scheme was evaluated by means of trace-driven simulations using a large dataset from a commercial nationwide IPTV service. The dataset comprises 255 thousand users, 150 TV channels, and covers a 6-month period. We show that by using our scheme IPTV service providers can save a considerable amount of bandwidth while affecting only a very small number of TV channel switching requests. To understand how these bandwidth savings are translated in energy savings, we developed a power consumption model for network equipment based on real measurements. The main conclusions are that while today the bandwidth savings will have reduced impact in energy consumption in the core network, with the introduction of very high definition channels this impact will become significant, justifying the use of resource-efficient distribution schemes such as the one proposed.