Research Assistants: S. Wang, S. Li, T. Buggs, K. Brown
Sponsors: NSF, AT&T
Multimedia data objects such as audio, video, and images are very large in size and are needed in several time-critical applications. The focus of this research is to efficiently transport multimedia objects over the WAN using a protocol such as UDP which is made as reliable as TCP but has less overhead.
We have conducted a series of experiments to investigate the transmission of different sizes of packets, using both TCP and UDP, on an Ethernet LAN, a WAN and an ATM LAN. We have proposed a method called 'UDP Cooling' which can improve the performance of UDP and studied its applicability to distributed multimedia systems.
We also propose a new method called Multi-pass Transmission Policy (MpTP) which combines several ideas such as sending small packets, selective retransmission requested by the receiver, and multi-pass transmission. We have conducted experiments to compare the efficiency of MpTP and TCP and determined the optimal datagram size for MpTP. We have developed some guidelines for achieving optimal performance when transmitting multimedia objects over the network.
We are also investigating the usage of lossy transmission protocols to transmit multimedia data. The multimedia data object is reconstructed at the receiver's site based on the data received. This approach is straight forward if the multimedia data is uncompressed but if its compressed, we have to be careful regarding what data can be lost.