Secure Multi-Constellation GNSS Receivers with Clustering-Based Solution Separation Algorithm

Because of the limited satellite visibility, reduced signal reception reliability and constraining spatial geometry, e.g., in urban areas, the development of multi-constellation global navigation satellite systems (GNSS) has gained traction rapidly. GNSS-based applications are expected to handle observations from different navigation systems, e.g., GPS, GLONASS, Bei-Dou and Galileo, in order to improve positioning accuracy and reliability. Furthermore, multi-constellation receivers present an opportunity to better counter spoofing and replaying attacks, leveraging approaches take advantage of the redundant measurements. In particular, cluster-based solution separation algorithm (CSSA) proposes to detect and identify faulty/malicious signals in a single GPS constellation by checking the consistency of receiver positions calculated with different number of satellites. Intuitively, the algorithm targets directly the consequence of spoofing/replaying attacks: the victim receiver position error estimation. It works independently of how the attacks are launched, either through modifying pseudorange measurements or manipulating the navigation messages, without changing the receiver hardware. Multi-constellation GNSS receivers utilize all observations from different navigation systems, there are more than 30 available satellites at each epoch after Galileo and BeiDou systems become fully operational; in other words using abundant redundancy. Therefore, we introduce such a CSSA to a multi-constellation receiver. The work shows that a multi-constellation GNSS receiver equipped with our algorithm works effectively against a strong spoofing/replaying attacker that can manipulate a large number of signals, or even an entire constellation. The results show that CSSA with multi-constellation significantly improves the performance of detecting and identifying the malicious signals; particularly, when the adversary cannot control all the constellations, a multi-constellation receiver can identify the faults even the adversary induces very small errors to pseudorange measurements, comparing with a single constellation receiver. Moreover, when the attacker is powerful to manipulate most of signals of all the constellations, a multi-constellation receiver with CSSA can still detect and identify the faulty signals with high probability when the attacker tries to mislead the victim more than a couple of hundred meters from its true location.