GNSS Vulnerability: A Taxonomy

Sources Of Gnss Vulnerability

The categories of vulnerability are shown in Figure 1, with arrows indicating a breakdown of more general categories into lower level categories. Figure 1 does not indicate the overall structure of the chapter, because the highest level of Figure 1 includes vulnerabilities to systems that use and augment GNSS. However, it is important here to acknowledge that these vulnerabilities exist, and are important to users and integrators of GNSS systems. Augmentation systems such as space-based augmentation systems (SBAS), continuously operating reference station (CORS) networks, real-time kinematic (RTK) systems, differential GPS (DGPS), and assisted GPS (AGPS) all have vulnerabilities of their own, but are not considered further here. Similarly, systems that integrate GPS can suffer where reported GPS positions can be intercepted and modified (spoofed) (Hackett, 2015). This type of vulnerability is also not considered further here.

We first consider the three segments of a GNSS system: the space segment, the control segment and the user segment. When speaking about GNSS vulnerability, most people think only of signal interference in the user segment. This will be dealt with in a later section. Here we consider the control and space segments.

Figure 1.

High-level Categories of where GNSS vulnerability can occur. In other words, vulnerabilities occur at system and segment levels, as well as the better known examples at lower levels. The box at the bottom right is expanded further in Figure 2.