Inter-link interference is one of the major factors that affects the performance of Wireless Mesh Networks. An {\em interference map} indicates possible spatial reuse, which can help improve the throughput of a TDMA-based network by reusing the same time slot for different non-interfering links. It is also a key input in both channel assignment and routing algorithms for the TDMA-based networks.
In this work, we have first performed various controlled measurements to study interference in realistic outdoor settings and determined the relation between the RSSI and interference. Based on the observations, we have developed a three way classification strategy to classify link-pairs according to the interference values. The classification strategy also takes care of the inherent RSSI variability observed in outdoor wireless links. It uses the SIR values approximated from the individual RSSI measurements, requiring only O(N) broadcast measurements for a network with N nodes.
We have also developed an automated mechanism, which performs these measurements periodically and generates an interference map. The time period of the measurements and the duration of each measurement is determined by time-series analysis of 24/48 hour long duration data. The work done is specific to outdoor TDMA-based networks.
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Pradeep Gopaluni can be reached at pradeep.gopaluni[AT]gmail.com.