Layered multicast is a common approach for dissemination of audio and video in heterogeneous network environments. Layered multicast schemes can be classified into two categories – feedback-based and feedback-free – depending on whether or not the scheme delivers feedback to the sender of the multicast session. Advocates of feedback-based schemes claim that feedback is necessary to match the heterogeneous receiver capabilities efficiently. Supporters of feedback-free schemes believe that feedback introduces significant complexity and that a moderate amount of additional layers can balance any benefit the feedback provides. Surprisingly, there has been no systematic evaluation of these claims. This paper provides a quantitative comparison of feedbackbased and feedback-free layered multicast schemes with respect to aligning the provided service to the capabilities of heterogeneous receivers. We discover realistic scenarios when feedback-free schemes require a very large number of...
Sergey Gorinsky, Harrick M. Vin