A Reliable PLCP-based Multicast Protocol for IEEE 802.11 WLAN

In current IEEE 802.11 WLAN, the unicast provides a reliable way of communication thanks to the use of acknowledgement feedbacks. As to the multicast, it suffers from unreliability and inefficiency. Recently many protocols have been designed for 802.11 such as Leader Based Protocol (LBP), to provide a reliable multicast transport. Yet no optimal solution has been proposed. In this paper we present Reliable PLCP-based Multicast Protocol (RPMP), a new reliable multicast protocol as an extension to the 802.11g and 802.11a. RPMP achieves reliability through the use of Negative Acknowledgements (NAK). We reduce the transmission overhead of our protocol, compared to other NAK-based proposals, by adding one additional OFDM symbol in the Physical Layer Convergence Procedure (PLCP) header of the multicast frame instead of using additional control frames. Further we show, based on our simulation results that the delivery ratio of RPMP remains at 100% in a lossy channel when it falls down to 50% with the standard. We also show that the efficiency of RPMP is much more enhanced than that of LBP.