ITEE Innovation Expo 2008 : Project Details

Context-aware vertical handover of video streams

Mobile Devices such as iPhones often have multiple network interfaces, such as Wi-Fi and 3G. When one network connection is lost, any data that is being transferred on that network can be handed over to the other network. Ideally, this handover will minimise the delay and number of dropped packets. These factors are especially important for streaming real-time video.

It is assumed that only existing and well-established link-layer, network-layer, and transport-layer procols will be used, and no changes can be made to these protocols. It is also assumed that there is a high latency between the Video Server and the Mobile Device, and preparing a network connection can have some delay, e.g. for authentication.

The goal of this project is to create a system which implements vertical handover and overcomes these problems. This system will add Proxies to each network which can assist in executing a handover by rerouting data through one another while waiting for the Video Server to change destination. The system will be controlled by a centralised Context Manager which collects information about the system, such as network availability and quality of service, cost, and video bitrate. Making use of context information adds extra flexibility. Instead of executing a handover only when a connection is completely lost, the Context Manager can intelligently evaluate and adapt to the situation by issuing commands to other agents, such as telling the Proxies to prepare connections to the Mobile Device, telling the Proxies and Video Server to execute a handover, and telling the Video Server to modify the video bitrate. This architecture should result in better performance, which will be tested in a simulation.