Improvement of channel zapping time in IPTV services using the adjacent groups join-leave method

Reducing the channel zapping time is critical problem to resolve for the spread of the IPTV service. In general, channel change times depends on several Parameters: command processing time, network delay time, STB layer delay time, STB jitter buffer delay time and MPEG decoder time. We focus on the network delay time, which does not exist in the traditional broadcasting service such as terrestrial, cable, or satellite broadcasting service. This could weaken the spread of IPTV service. In this paper we present the method of improving the channel zapping time by making adjacent multicast groups of current channel come to home gateway in advance. When IP STB requests join to new channel by sending IGMP membership report message, home gateway sends not only IGMP membership report message for the channel but also for the adjacent channels. Therefore multicast streams for the adjacent channels of current one always come to home gateway. When IP STB requests join to an adjacent channel, home gateway can forward the corresponding multicast stream immediately.