Dynamic content distribution using ALIVE system in wireless network

This paper proposed the efficient distribution of live and scheduled multimedia content to mobile users via a ubiquitous wireless Internet. The objective is to design and develop a dynamic content delivery system that (1) enables content owners to deliver their multimedia content to a large number of heterogeneous receivers, and (2) enables receivers to continuously receive that content, independent of their location and the network they connect to. Previous investigations into this topic have shown that multimedia content can be efficiently distributed through an overlay network that consists of multiple distributed proxy servers. In this paper, we extend this concept to the distribution of live and scheduled multimedia content through multiple aggregators. An aggregator is an intermediary content provider that aggregates live multimedia content from various content sources and delivers it to mobile users through a pool of proxy servers. The availability of the same content through multiple aggregators enables mobile users to switch from one aggregator to another, thus alternately receiving the same content from different aggregators. The service area of an aggregator may be restricted to a certain set of networks, in which case switching to such an aggregator also requires mobile hosts to handoff to a network that is part of the aggregator's service area. To support roaming users, aggregators establish application-level roaming agreements between each other. These agreements enable users to receive channels from multiple aggregators while having a subscription with only a few of them. The system transparently switches mobile hosts from one aggregator to another and executes handoffs on the mobile host's network interfaces. The system switches a mobile host to the aggregator that provides a certain channel in the best configuration, where `best' is defined by the preferences of the end-user. Our analysis consists of two parts: (1) a heuristic analysis of the application and network-level delay components involved in a typical switch and an estimation of their best-case values, and (2) an empirical analysis of the delay introduced by SIP transactions under various 802.11 network conditions. The analysis shows that the ALIVE system usually experiences little delay, except at the very edge of an 802.11 cell. Based on our implementation and measurement work, we conclude that the ALIVE system is a feasible system that provides a clear contribution to the multimedia-everywhere vision.