Highly Reliable Multicast Protocol Using Relay Retransmission For Wlans

In this letter, a new multicast medium access control protocol for wireless local area network(WLAN) system is proposed to achieve high reliability. Multicast in conventional WLANs offers highly efficient use of wireless resources, but has disadvantages of low reliability and low data rates due to lack of feedback. Our proposed multicast frame includes a sequence that indicates the stations (STAs) that send the ACK frame first. Using the sequence, the proposed system makes feedback for the multicast frame. If some STAs fail to receive the frame, the other STAs that have successfully received the frame retransmit the frame. The proposed multicast protocol with relay retransmission can achieve a 100% frame delivery ratio in a strong-fading channel while IEEE 802.11aa multicast protocol cannot. The proposed multicast protocol can also conserve 48% throughput to the maximum data rate in a strong-fading channel.