Realtime multimedia transport using multiple paths.

摘要

Realtime multimedia transport usually has stringent bandwidth, delay, and loss requirements, which is not supported in the current best-effort Internet. Video packets may be dropped due to congestion in the network, or frequent link failures typical in ad hoc networks. However, the mesh topology of these networks implies the existence of multiple paths between two nodes. Multipath transport provides an extra degree of freedom in designing error resilient video coding and transport schemes.; We propose to combine multistream coding with multipath transport for video transport over ad hoc networks. We studied the performance of three schemes, two proposed in our work, and one chosen from previous work, via extensive simulations using the Markov channel models and OPNET. We also implemented an ad hoc multipath video streaming testbed to further validate the advantages of these schemes. The results show that great improvement in video quality can be achieved over the standard schemes with limited additional cost.; We also present an analytical framework on optimal traffic partitioning for multipath transport. We formulated a constrained optimization problem using deterministic network calculus theory, and derived its closed form solution. Compared with previous work, our scheme is more realistic, and is easier to implement. Depending on the system parameters, we can either achieve a minimum end-to-end delay equal to the maximum fixed delay of the paths, or equalize the delays of all the paths.; We design a new protocol, called the Multi-flow Realtime Transport Protocol (MRTP), to support the realtime multimedia transport using multiple paths. MRTP is a natural extension of the RTP/RTCP protocol for multiple paths, and is complementary to SCTP in that it supports multimedia services. We present two performance studies to demonstrate the benefits of using MRTP.; Finally, we study fundamental scheduling problem using the Generalized Processor Sharing (GPS) discipline. We derived the effective bandwidth of a class, and designed an admission control test. We also presented a tight service bound, resulting in a higher bandwidth utilization than the previous work, and extended previous work on Matrix Analytic Methods for stochastic flows to GPS analysis.