Accurate wireless indoor position estimation by using hybrid TDOA/RSS algorithm

Location Determination in an indoor environment is a challenge being faced by wireless industries. The concept of the indoor geolocation was established in order to provide the user´s location inside buildings during an emergency where global navigation satellite system (GNSS) services are not available. Keeping public safety in mind, it is important not only to estimate the position, but also to provide a high level of reliability. The paper presents practical results and issues related to the accuracy of an indoor geolocation system, which uses a wideband code division multiple access (WCDMA) signal at a 2.45 GHz carrier frequency. This experiment employs a hybrid Time Difference Of Arrival (TDOA) / Received Signal Strength (RSS) algorithm and a TDOA only algorithm. Practical results indicate that the positioning performance is improved by using the hybrid TDOA/RSS algorithm as compared to the TDOA only algorithm.