A block ACK transmission scheme for reliable multicast in IEEE 802.11 WLANs

Multicast over wireless medium is considered for multimedia service such as YouTube and NetFlix. However, the multicast frames are sent in a low data rate without the feedback in IEEE 802.11. The low data rate of multicast causes performance anomaly problem. In this paper, we propose a feedback overhead reduction scheme to guarantee the reliable multicast, and to sustain the high throughput in recent IEEE 802.11. In our proposed scheme, multicast members send acknowledgement frames when they miss data frames. Multicast data frames are retransmitted according to the acknowledgment. The attempt to shrink the overhead for the feedback allows the opportunity to transmit more data. In simulations, our proposed scheme alleviates the degradation of the network throughput according to the increase of the multicast group size.