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Due to the blockage of satellite signals by the buildings and other structures, the high-accuracy, reliability and real-time indoor location-based services is one of the challenges for BeiDou navigation satellite system. As one of the core technologies of the spatio-temporal digital foundation for future artificial intelligence and super-intelligence applications, high-precision indoor positioning has long been a research hotspot in industry and academia. This paper first reviews the development status of existing high-precision indoor positioning technologies, and compares their advantages, disadvantages and difficulties. Then it analyzes the development trend of related technologies under typical applications, and looks forward to the fu ture development direction and application scenarios of indoor positioning technologies. [ABSTRACT FROM AUTHOR]

Navigation signal augmentation from low earth orbit (LEO) can improve the slow convergence and weak signal problem of the high/medium earth orbit navigation satellites, so it plays an important role in next generation navigation technique. Luojia-1A scientific experimental satellite deve-loped by Wuhan University carried the navigation augmentation payload, and it is capable of automatically calculating its orbit and clock by it self, generating and transmitting dual-frequency ranging signals. Luojia-1A satellite successfully demonstrates the navigation signal augmentation from LEO platform. This paper assesses the quality of the navigation augmentation signals from Luojia-1A from C/N0, precision of pseudorange and carrier phase and timing precision from single satellite. The results indicates the precision of the pseudorange and carrier phase at high elevation angle is 1.5 m and 1.7 mm respectively, which can meet the requirement of the navigation signal augmentation. Single satellite based timing precision from Luojia-1A is approximately 10-30 ns,which proves the correctness and validity of the satellite-ground ranging signals. [ABSTRACT FROM AUTHOR]

Indoor positioning is currently a research hot topic for industrial and scientific communities. Wi-Fi signal has been a common positioning signal adapted researchers. Received signal strength indicator is a traditional measurement used for indoor positioning. It can be easily affected by many factors such as the change of environment. Therefore, it is difficult to achieve such an accuracy that can be used in practice and hard to deploy the positioning solution in a large-scale. More and more resear-chers are now focusing on using channel state information as the measurement, which contains an essential description of Wi-Fi signal propagation and provides more details about the communication channel. This information can be transformed to a useful measurement for positioning. In this paper, we introduce the fundamental description of channel state information and classify the positioning approaches into three categories, which are fingerprinting-based, angle of arrival-based and ranging-based, respectively. The current states of these technologies have been reviewed in details, and the pros and cons have been identified and compared. We conclude the paper with a discussion about the directions in this field. [ABSTRACT FROM AUTHOR]