Buffered data management for mobile multimedia systems
Student thesis: Doctoral Thesis
Related Research Unit(s)
The advances in mobile communication technologies not only create a wide range of new applications but also perennially bring applications from wired to wireless devices. However, the intrinsic differences between mobile and wired networks require careful redesign and modification of existing resource management algorithms in order to maintain the efficiency and promised quality of services in providing real-time multimedia information to mobile users. In this thesis, we concentrate on the problems of delivering multimedia information over a mobile network to mobile clients. Multimedia data can be broadly classified into two categories: real-time and non-real-time. The former includes video clips and audio clips that play on-fire. Therefore, timely delivery is the primary requirement in performance. For non-real-time contents such as pictures and texts, consistent and efficient retrievals are the main concerns. Despite the diverse service requirements, buffering techniques are widely used in mobile devices to improve the performance and to deal with variation in network connectivity. Therefore, we have investigated a number of approaches to manage the buffered data in multimedia applications. Firstly, we proposed a buffered sensitive scheduling algorithm to address the fairness and real-time issues in delivering video streams over a wireless network. The amount of video data pre-fetched in the client’s buffer actively affects the scheduling decision. Then we extended the algorithm for cellular network in which admission control is the main focus. Instead of optimizing the performance at each client, we explored the possibility of co-operative use of client buffers to maintain the smoothness in video playback under location dependent errors in a mobile network. This co-operative usage of client’s buffers is conceptualized as buffered bandwidth. We applied the buffered bandwidth in call admission control with the purpose to minimize the problem of network overloading on the whole system performance. Finally, for non-real-time data, we proposed a new cache invalidation scheme on managing the buffered data in mobile clients with the purpose to maintain the consistency of information to be presented to each mobile client.
- Multimedia communications, Mobile communication systems