The Performance and Simulation of a C-CDMA Pseudolite Indoor Geolocation System
Ilir F. Progri, W. Ortiz, William R. Michalson, Jinling Wang · Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) · 2006
Previously we have discussed the principle of operation, the transmitter and receiver design of an Orthogonal Frequency Division Multiplexing (OFDM) Frequency Division Multiple Access (FDMA) (OFDMA) indoor geolocation system. We have also presented the OFDMA indoor geolocation system theoretical performance and some preliminary simulation results. At the transmitter, the geolocation information consists of the transmitter’s position and time. For each transmitter this information is binary encoded data at a rate of 1 KHz. The encoded geolocation signal is modulated on the corresponding [2.0 2.3 2.6 2.9] GHz carrier signal via a FDMA modulator to resist interference encountered in an indoor environment. The OFDM signal is then used to provide distance information. Four (4) transmitters are simulated to enable a geolocation estimate on the receiver. Second, the channel consists of: (1) delay model and (2) an additive white Gaussian noise. Third, the receiver consists of four channels each one of which is designated to each transmitter. On each receiving channel the received signal is down-converted in the baseband. Then the signal is demodulated and decoded. As a result we can obtain an estimate of the distance between the transmitter and the receiver. Four distance estimates are used in Least Squares filter to provide an estimate of the receiver location and time. It appears that an OFDMA pseudolite indoor geolocaiton system may provide sub-meter 3-D position error 99.9 % of the time given that the pseudorange error is 10 cm or less.