Nowadays low cost UMTS and HSDPA mobile networks and broadcast systems such as DVB-T and DVB-H lead to an increase of multimedia broadcasted services. The new standard for broadcast over mobiles, DVB-H, needs service reliability. This issue is tricky, because in a broadcast transmission, the sender may not be able to receive all acknowledgements from all users in order to retransmit as in TCP. Moreover real time multimedia diffusion enforces constraints on this system, such as restricted transmission delay. In this paper, we evaluate the performance and benefits of using a separate return channel for quality of service of a broadcast diffusion. Peer-to-peer links between the receivers are used in order to allow local retransmissions and estimation of the loss rate with low risk of feedback implosion on the central server. Other techniques such as FEC should be combined to this system in order to reach "quasi error free transmission", as recommended by the DVB workgroup