A performance comparison between ROC-RSSI and trilateration localization techniques for WPAN sensor networks in a real outdoor testbed.

In sensor networks 802.15.4 WPAN, the most common technique used to calculate the distance between two nodes is the RSSI (Received Signal Strength Indicator) technique, because it has the advantage of not requiring additional hardware and synchronization on nodes. Some studies show that the RSSI index is fairly unreliable and often produces significant errors about the location of the nodes in the network. In this paper an approach to the problem of nodes localization in outdoor environment is proposed. In order to obtain more accurate distance estimation a scenario dependent ranging technique has been adopted. The goodness of the ranging model is estimated through a comparison with the classic model based on the path-loss log-distance; then two localization techniques such as Triangulation and RocRssi+ are used in order to test the improvement obtained for the estimated positions of nodes within the network.