To solve this problem, Tan Shusen proposed comprehensive RDSS (CRDSS) that combines RNSS and RDSS, thus implementing RNSS and RDSS observations simultaneously. When a reliable elevation library is unavailable, the RDSS positioning accuracy will be very poor because the geostationary (GEO) satellites carrying the RDSS payload are all distributed in the equatorial orbit. A standard RDSS relies on an elevation library. Compared with other navigation satellite systems, the BeiDou system has the radio determination satellite service (RDSS) capability as well as the radio navigation satellite service (RNSS) capability. To achieve better anti-spoofing performance, more features of navigation system should be explored and utilized.įortunately, the BeiDou system has such features. The methods mentioned above have room for improvement. Techniques with additional sensors, such as multiple antennas, power measuring equipment, and inertial navigation systems (INSs) are usually robust, but the expense increases greatly when precise sensors are added. However, these methods are not practical as they require changes to the current system.
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Spread spectrum security code (SSSC) and navigation message authentication (NMA) can recognize spoofing signals by encrypting a civil signal.
Receiver autonomous integrity monitoring (RAIM) can inspect the measurements consistency, therefore, it can exclude one or two spoofing signals, but a great number of spoofing signals will invalidate the method. They may falsely judge multipath signals as spoofing ones because multipath signals may also distort the correlation peak. Signal quality monitoring methods detect spoofing signals from correlation peak distortion. There have been many pieces of research on anti-spoofing. Spoofing mitigation ensures that a user can obtain a correct navigation solution under spoofing attacks. Spoofing detection detects a spoofing attack and determines whether the navigation solution is reliable. Anti-spoofing ability can be divided into two categories: spoofing detection and spoofing mitigation. Therefore, anti-spoofing is of great significance in modern navigation applications. Spoofing signals usually lead to erroneous time delay measurements, ultimately misleading the positioning and timing results of the user.Ĭonventional receivers usually do not consider the impact of spoofing attacks that may result in terrible consequences. On the other hand, although military signals are encrypted, a spoofing device can still spoof a military user by replaying the authentic signals and adding delays. Because the structure of civilian navigation signal is open to the public, a spoofing device can easily generate signals that can suppress authentic signals, thus, misleading a victim receiver to track spoofing signals. Spoofing attacks are key issue in navigation security. With the development of the global navigation satellite system (GNSS), satellite navigation security issues have become increasingly significant.