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An Improved Active Network Concept and Architecture for Distributed and Dynamic Streaming Multimedia Environments with Heterogeneous Bandwidths
A problem in todays Internet infrastructure may occur when a streaming multimedia application is to take place. The information content of video and audio signals that contain moving or changing scenes may simply be too great for Internet clients with low bandwidth capacity if no adaptation is performed. In order to satisfactorily reach clients with various bandwidth capacities some works such as receiver-driven multicast and resilient overlay networks (RON) have been developed. However these efforts mainly call for modification on router level management or place additional layer to the Internet structure, which is not recommended in the nearest future due to the highly acceptance level and widely utilization of the current Internet structure, and the lengthy and tiring standardization process for a new structure or modification to be accepted. We have developed an improved active network approach for distributed and dynamic streaming multimedia environment with heterogeneous bandwidth, such as the case of the Internet. Friendly active network system (FANS) is a sample of our approach. Adopting application level active network (ALAN) mechanism, FANS participants and available media are referred through its universal resource locator (url). The system intercepts traffic flowing from source to destination and performs media post-processing at an intermediate peer. The process is performed at the application level instead of at the router level, which was the original approach of active networks. FANS requires no changes in router level management and puts no additional requirement to the current Internet architecture and, hence, instantly applicable. In comparison with ALAN, FANS possesses two significant differences. From the system overview, ALAN requires three minimum elements: clients, servers, and dynamic proxy servers. FANS, on the other hand, unifies the functionalities of those three elements. Each of peers in FANS is a client, an intermediate peer, and a media server as well. Secondly, FANS members tracking system dynamically detects the existence of a newly joined computers or mobile device, given its url is available and announced. In ALAN, the servers and the middle nodes are priori known and, hence, static. The application level approach and better performance characteristics distinguished also our work with another similar work in this field, which uses router level approach. The approach offers, in general, the following improvements: FANS promotes QoS fairness, in which clients with lower bandwidth are accommodated and receive better quality of service FANS introduces a new algorithm to determine whether or not the involvement of intermediate peer(s) to perform media post-processing enhancement services is necessary. This mechanism is important and advantageous due to the fact that intermediate post-processing increases the delay and, therefore, should only be employed selectively. FANS considers the size of media data and the capacity of clients bandwidth as network parameters that determine the level of quality of service offered. By employing the above techniques, our experiments with the Internet emulator show that our approach improves the reliability of streaming media applications in such environment.
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