A simple and effective cross layer networking system for mobile ad hoc networks

We propose a novel cross layer design concept that could improve the network throughput significantly for mobile ad hoc networks. The channel reservation control packets employed at the MAC layer can be utilized at the physical layer for exchanging timely channel estimation information to enable an adaptive selection of a spectrally efficient transmission rate. In particular, the size of a digital constellation can be varied dynamically based on the channel condition estimated at the receiver which can be relayed to the transmitter via the control packets. In addition, this channel adaptive information gathered at the MAC layer can be communicated to the routing layer via different routing metrics for optimal route selection. We have examined the performance improvement at the network layer due to cross layer communications. For this, we present a simple cross layer design implemented with minor modifications on the IEEE 802.11 standard and the dynamic source routing (DSR) protocol. We demonstrate that the network throughput is significantly increased, as much as 50% to 100%, in low mobility scenarios simulated using ns-2.