Date Added: Dec 2009
The selection of high-throughput routes is a key element towards improving the performance of wireless multihop networks. While several routing metrics have been proposed in the literature, it has been shown that link-quality aware metrics can provide significantly higher end-to-end throughput. To date, the online computation of such metrics requires the periodic transmission of probe packets at all available transmission rates. However, the authors' link level measurement study on two different 802.11 testbeds demonstrates that: multi-rate probe transmissions increase the number of collisions and enforce nodes to reside in the back-off state for prolonged time periods, and the extent of performance degradation depends on the network density; a network-wide throughput reduction of the order of 400% is possible.