Conclusion and Ongoing Work

In this paper, we considered the problem of estimating pairwise interference among links in a multi-hop wireless testbed. Using experiments done in a 22-node, 802.11-based testbed, we showed that some of the previously-proposed heuristics for predicting pairwise interference are inaccurate. We then proposed a simple, empirical methodology to estimate pairwise interference using only $O(n^2)$ measurements. We showed that our methodology accurately predicts pairwise interference among links in our testbed in a variety of settings. Our methodology is applicable to any 802.11-based wireless network where nodes use omni-directional antennas.

There are several avenues for future work. We hope to increase the accuracy of our methodology by accounting for the impact of four factors that we ignored in this paper. These four factors are: (i) retransmissions of lost unicast packets, (ii) RTS/CTS handshake (iii) collisions between data and ACK packets (iv) autorate algorithms.

We would like to extend our approach to estimate interference among larger groups of links, instead of just pairwise interference.

Finally, we note that our methodology requires nodes to generate broadcast traffic, and existing traffic on the network can significantly reduce the accuracy of our approach. We are currently exploring the possibility of determining interference patterns by simply observing correlation between existing traffic flows on the network.