Exploiting unicast vs. multicast delivery tradeoffs to improve the latency performance for IPTV channel change

In IPTV networks, channel change latency represents a major obstacle in achieving broadcast-level quality video delivery. Since the content for channels, other than the one currently viewed, is not readily available at the client side, to receive the content corresponding to these channels, each request needs to go through the network, leading to significant, and oftentimes unacceptable, delays. To minimize this latency, various approaches have been proposed. These approaches typically require the use of dedicated servers near the access network to speed up the delivery of channel change packets. In this paper, we use such server-driven framework to develop a joint unicast- and multicast-based channel change protocol that relies on the use of (i) session-dependent multicast channel change streams to deliver the key-frame content to the zapping clients, and (ii) a dedicated unicast streaming server, which is referred to as the Channel Switch Coordinator (CSC), to deliver the channel change packets corresponding to the non-key-frames. In our framework, CSC server is also responsible for coordinating the received channel change requests and optimally allocating system resources for each received request.