Immediate Group ACK tree (IGA) for reliable multicast in mobile Ad Hoc networks

In this paper an efficient protocol, called Immediate Group ACKTree (IGA), is proposed to support reliable multicast service for mobile ad hoc networks. For most reliable multicast protocols, a recovery scheme is used to ensure end-to-end delivery of unreliable multicast packets for all group members. IGA use a directly-related based recovery mechanism that localizes ACKs and retransmissions to avoid forward and feedback flooding. Our approach constructs an immediate ACK tree to three generations of nodes and uses efficient Fast-Upstream recovery algorithm to maintain reliable multicast and reduce overhead. When a tree is fragmented due to a departed node, the fragments will be glued back to the tree using the directly repair protocol. IGA adopts an adaptive scheme to recover missed packets that have been multicast to the group during fragmentation. We simulate the performance among IGA, FAT and source ACK approaches. The results show that IGA achieves better performance in terms of reliability, scalability, and delivery efficiency in ad hoc networks due to the speedy of recoverable service.