In IPTV networks, channel change latency is a major concern for achieving the desired quality of experience at the subscribers. Since IPTV connections are established over limited capacity links, the number of channels available to each subscriber's use, at any given point in time, is strictly limited. As a direct consequence of this limitation, channel change requests need to go through the IP infrastructure, causing significant, and oftentimes unacceptable, channel switching delays. To minimize this latency, various approaches have been proposed. Among these approaches, server-based approaches are shown to achieve the best latency performance. However, since server-based approaches typically utilize unicast-based delivery techniques, they are susceptible to introducing significant overhead at the designated servers, leading to scalability related problems. In this paper, we address these problems by proposing a semi-distributed, i.e., user-assisted server-based, channel change framework. The proposed approach integrates the capabilities of a dedicated channel change server with that of IPTV subscribers to create a resource-efficient and scalable channel change framework. Through extensive simulations, we showed that the proposed framework can achieve sufficiently low channel change latency values, while significantly improving the servicing capacity of the network when compared to server-based-only channel change policies.
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