Indoor Navigation and Multipath Mitigation Using Code-Offset Based Pseudolite Transmitter Array

摘要

Recently, indoor positioning is the hot issue in navigation application part. New signal repeating technique to deal with GNSS indoor positioning by means of signal transmission delay of outdoor GPS signal is proposed by authors[1]. For the solution to the efficient assignment of C/A code and the synchronization problem in pseudolite, we extend the proposed algorithm, which positioning technique is based on the signal delay(or code offset), to pseudolite configuration technique [2]. rnDespite continuing improvements in GNSS positioning system and receiver technologies, multipath has remained as dominant error. Accurate indoor positioning in non line-of-sight(NLoS) environments is an open research topic due to interfering dense multipath propagation. The key challenge is to reliably detect the direct signal (DS) from the transmitter to the receiver so as to enable accurate positioning calculations. Array antenna-based techniques are remarkable in multipath mitigation. But, in man’s navigation, its utilization is limited by an inherent low portability results in array-antenna size. In 2008, an inverse beamforming technology was introduced by Sasha Draganov [3]. Inverse beamforming technique allows a receiver to beamform without array antenna. Therefore, a conventional GNSS receiver can process the arrayantenna signals without hardware modification. rnIn this paper, we propose the indoor navigation system using a code-offset based pseudolite transmitter array antenna system. User receiver technologies such as methods of array processing for mitigating a multipath and integrated carrier-phase based multipath mitigation are, also, proposed and evaluated. Finally, we practically tested the proposed system in indoor environment. For the real test, we implemented a transmitter array pseudolite using code-offset and a software GNSS receiver to process the code-offset based array antenna signals.