Mitigate Funnel Effect in Sensor Networks with Multi-interface Relay Nodes

Overlay network architectures that use orthogonal channels have been known to provide effective additional resources to underlying networks in high demand. Overlays are composed of relay nodes provided with rich computational resources and multiple wireless interfaces that make them capable of establishing several non-interfering networks. These networks can be used to move traffic around in a non-interfering manner. It is possible to deploy such overlays in sensor networks where sensors suffer from the funnel effect caused by excess traffic flows, to help mitigate this effect. In this paper we address the geographical placement of relay nodes in the region to mitigate the funnel effect in sensor networks. We provide an O (mlog (h) ) algorithm of congested region size m and computed Convex Hull size h that finds the placement of the minimum number of relay nodes to cover the entire congested region. In a greedy fashion, we place a relay node given the following placement conditions: the closest position such that it covers the largest amount of peers up to an extent parameter bounded by its transmission range, and that is closest to the sink. Our simulated results show that using a minimum number of relays, we could save up to 43% of nodes compared to a simple placement strategy, the underlying network increases its delivery ratio and throughput, improves its jitter, and opens the possibility of load balancing and fairness advantages.