Achieving accurate geo-location detection using joint RSS-DOA factor graph technique

This paper proposes a detection technique based on factor graph (FG) to estimate the position of radio wave emitter. To obtain accurate estimation, we combine received signal strength (RSS) and direction of arrival (DOA) schemes into a single factor graph, called joint RSS-DOA, where soft information as mean and variance of the estimated target position are exchanged between the two schemes. The performance of DOA in this paper is used to modify variance approximation of the target location. We introduce the weighting factors for RSS and for DOA to avoid the soft information of DOA factor graph be ignored. With the proposed technique, the complexity is kept low, because only mean and variance are exchanged between the factor nodes. Ray-tracing data is used in outdoor application to create power delay profile (PDP) for the RSS-based factor graph and evaluate 5, 10, and 20 training points. The results confirmed that proposed joint RSS-DOA has best accuracy in detection compared to RSS-based or DOA-based only factor graph. To the best of our knowledge, we are the first showing successful results of FG based geo-location using Ray-tracing data.