Improving Zap Response Time for IPTV

Channel zapping is the act of changing from one television channel to another. Zap response time is the time it takes for the new TV channel to start playing from the time a request to zap to that channel occurs. In digital TV systems such as IPTV where TV channel content is transported as an MPEG-2 or MPEG-4 data stream encapsulated in IP packets, zap response time is a significant concern. 

This is due to the requirement that for an MPEG stream, which is a series of groups of pictures (GOPs), playout can only start at the beginning of a GOP. The time between the occurrence of a zap event to the time to the beginning of the next GOP, which can be anywhere from less than a second to a few seconds, is a significant contributor to zap response time. 

It is widely accepted that such large zap response times can significantly hamper IPTV quality of experience (QoE) and an efficient solution to this problem is therefore a business imperative. Existing solutions to this problem are bandwidth inefficient either on the last mile, or within the video distribution network, or both. We present a novel solution that is significantly efficient in terms of bandwidth utilization and zap response time. We derive and present the theoretical bounds for our solution and quantitatively demonstrate the properties of our solution through results from extensive simulations.