Review of Timing and Positioning with OFDM

OFDM signal systems have been widely used in mobile communications, digital satellite TV, and have provided higher transmission rate and positioning information service. It has the potential in timing and ranging. Because of limitation of GNSS signal strength, indoors, underground and in the other scenes, CDMA-based GNSS signal receiver sensitivity cannot meet the requirements, or serious in multipath influence, and poor in positioning accuracy. Satellite navigation positioning system based on ranging and transmission with OFDM is still a hot issue in the future. Satellite navigation and positioning is also facing new opportunities and challenges. Methods based on existing OFDM timing and ranging technology are analyzed, which point out that synchronization algorithm and channel estimation is the key to enhance accuracy. Therefore, this paper proposes three aspects of OFDM to enhance the accuracy: (1) Combination of a variety of signal system; (2) improving 2 pi limitation of TOA phase measurements in the frequency domain; (3) Accurate channel estimation utilizing OFDM signal.