While there have been quite a few layered multicast congestion control schemes capable of dealing with heterogeneity within a multicast group, they are coupled with multicast routing, which may imply some potential problems. Also, they are somehow complicated. In contrast, my philosophy is "The simpler is the better", so I am trying to develop a single rate congestion control scheme for source, without requiring any support from intermediate nodes (routers) and minimal support from receivers. Well, at least that will probably work for the multicast on intranet since the environment there is less heterogeneous. It that works, we might be able to do some artifical arrangment to deal with heterogeneity.
P.S.
I am also interested in application-layer multicast and peer-to-peer stuff, as well as network security which is my master research topic. However, for now I am unable to squeeze any time out of my fighting for degree...