Multicast QoS Support in IEEE 802.11 WLANs

Existing IEEE 802.11 spec. provides no error recovery mechanism (ARQ) for multicast traffic. ARQ absence in wireless networks unreliable by their nature leads to frequent packet losses, which is inappropriate for most of multimedia applications. In the paper, we propose new reliable multicast mechanism supporting multimedia QoS (packet loss ratio, delay and throughput), in IEEE 802.11 Wireless Local Area Networks (WLANs). This mechanism is based on the concept of multiple ACK-leaders, i.e. multicast recipients responsible for data packets acknowledging. We develop an analytical model of the mechanism and use the model to study and to optimize the mechanism.