DiCoR: Distributed cooperative repair of multimedia broadcast losses

Multimedia Broadcast/Multicast Service (MBMS) allows a common broadcast channel to be shared by users interested in identical content. We explore the problem of enhancing MBMS resilience by repairing packets lost during broadcast. Since MBMS broadcast consumes expensive 3G resources, we leverage the ubiquity of multi-homed mobile devices i.e., devices having both cellular and IEEE 802.11 wireless interfaces. We thus accomplish out-of-band repair of MBMS packet losses through an ad-hoc, peer-to-peer 802.11-based network. A fundamental challenge in scheduling repair transmissions is handling interference between distributed nodes. We present DiCoR, a fully distributed protocol for CPR. Our protocol does not assume any a priori knowledge of the network topology or peer losses, and is resilient to dynamic network changes due to node mobility or the continuous joining and leaving of peers. Detailed simulation experiments, under realistic loss models and network conditions, demonstrate that DiCoR presents a viable solution for timely out-of-band loss repair of MBMS real-time broadcast.