Reducing IPTV channel zapping time for scrambled services

In general, IPTV is defined as a multimedia delivery service and it is extended from the VoD service by unicast to live TV service by multicast. In the live TV environment, the QoE of IPTV service includes convenient user interfaces, quality of audio/video, and response time. The channel zapping time is one of the most important factors in QoE, and there have been many researches to improve it. Especially, because channel zapping in scrambled services includes a process for descrambling the contents, it is important to transmit the descramble keys efficiently to reduce the zapping time in scrambled services. In this paper, we improve this problem by receiving descramble keys from neighbor IP-STBs instead of from the multicast stream.