A hybrid TOA and RSS-based factor graph for wireless geolocation technique

This paper proposes a new hybrid time-of-arrival (TOA) and received-signal-strength (RSS)-based factor graph (TRFG) for wireless geolocation technique. The TOA-based FG (TFG) provides rough estimated position which is used to select the most appropriate monitoring spot positions, i.e., at least four monitoring spots surrounding the target, and initial target position for RSS-based FG (RFG) technique. The performance of the proposed technique is verified through making comparison with the conventional TFG-only technique suffering from imperfect time synchronization, as well as with the idealistic RFG technique, in terms of the root mean squared error (RMSE) of the estimate. It is shown that the RFG technique utilizing the result of TFG achieves close performance to the idealistic RFG technique where the optimal monitoring spots are assumed to be always correctly identified. Hence, the proposed technique outperforms the TFG-only technique in terms of estimation accuracy.