Reliable Multicast Scheme Based on Busy Signal in Wireless LANs

For unicast transmissions, the IEEE 802.11 WLAN MAC (Medium Access Control) layer has control packets such as RTS, CTS, and ACK. However, it has no such control packets for multicast transmissions. Therefore, it does not provide reliable multicast transmissions. Most of previous reliable multicast schemes are based on the ARQ (Automatic Repeat reQuest) used for unicast communications. Therefore, it causes the large number of packet transmissions and the excessive control overhead. In this paper, we propose a new reliable multicast scheme. The proposed scheme combines FEC (Forward Error Correction) and ARQ mechanisms to reduce the large number of packet transmissions. Also, it uses busy signals to improve efficiency by reducing the excessive control overhead. The simulation results show that the proposed scheme is more effective in terms of normalized throughput and average delay under a wide range of data packet error rates.