  In this research, we study the optimization challenges of MANET and
cross-layer technique to improve its performance. We propose an adaptive
retransmission limits algorithm for IEEE 802.11 MAC to reduce the false link
failures and predict the node mobility. We implemented cross layer interaction
between physical and MAC layers. The MAC layer utilizes the physical layer
information for differentiating false link failure from true link failure. The
MAC layer adaptively selects a retransmission limit (short and long) based on
the neighbour signal strength and sender node speed information from the
physical layer. The proposed approach tracks the signal strength of each node
in network and, while transmitting to a neighbour node, if it's received signal
strength is high and is received recently then Adaptive MAC persists in its
retransmission attempts. As there is high probability that neighbour node is
still in transmission range and may be not responding due to some problems
other then mobility. In this paper, we evaluate the performance of MANET and
show that how our Adaptive MAC greatly improves it. The simulation is done
using Network Simulator NS-2.
