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Multimedia services are a major application forIEEE 802.11 WLANs but the current standard does not utilize any rate adaptation technique for multicasting. SARM (SNRbased auto rate for multicast) is a new rate adaptation mechanism for multicasting multimedia content in IEEE 802.11 WLAN environments. Since there is no RTS/CTS or MAC ACK frame in multicast packet transmissions, SARM uses an auxiliary signaling method to obtain the channel quality for each mobile node. By adapting a transmission rate based on the SNR of the node experiencing the worst air-channel, SARM achieves the best quality of service for the prevailing conditions. This reduces the proportion of wireless channel resources assigned to multicasting, allowing more bandwidth for unicast flows.