Receiver blocking problem in mobile ad hoc networks: Challenges & solutions

The IEEE 802.11 has been shown to be quite inefficient in multihop networks. Besides the problems of hidden terminal and exposed terminal, there is also unreachability problem, which may result in link/routing failures and unfairness among multiple traffic flows. In this paper, a novel medium access control (MAC) protocol, called eMAC, is proposed. Under the proposed scheme, stations maintain double hop neighborhood (DHN) graphs while exchanging designated eMAC tables to share their knowledge about their neighbourhood topology. Using a DHN graph and an adaptive unreachability reporting mechanism, stations are reliably informed about their neighbours´ unreachability status; therefore, they avoid establishing link layer connections with their unreachable neighbours and consequently, network resources are not consumed for unsuccessful connection establishment efforts. Furthermore, we propose an adaptive table broadcasting technique to facilitate topology information dissemination in mobile ad hoc networks. Performance of the proposed schemes is evaluated and compared with earlier schemes through simulations.