Improving the reliability of IEEE 802.11 broadcast scheme for multicasting in mobile ad hoc networks

Broadcasting is one of the essential communication models of MANET. Many MANET multicast routing protocols rely heavily upon MAC layer's broadcast support. However, the broadcast mechanism of the standard IEEE 802.11 cannot provide reliable broadcasting service, and therefore, degrades the multicasting performance. In this paper, we propose an extension to the IEEE 802.11 broadcast mechanism, called round-robin acknowledge and retransmit (RRAR), to improve the reliability. Different from other mechanisms, we employ a simple and effective DATA/BrACK (broadcast acknowledgment) mechanism. Receiving the BrACK, the DATA sender calculates and records the indices of the frames that are lost and retransmits them. The proposed scheme provides a highly reliable broadcast service to the routing layer, and the performance of multicast routing protocols can be improved significantly.