Spoofing attacks toward Global Navigation Satellite System(GNSS) users aim at falsifying the position, velocity, and timing(PVT) results, and are therefore recognized as a security threat with severe consequences. As countermeasures, various anti-spoofing techniques are proposed to detect, recognize, and eliminate spoofing signals. A typical series of anti-spoofing techniques utilize the spatial characteristics of the spoofing signals. They share a common hypothesis that spoofing signals are transmitted by a single antenna and thus have identical propagation paths. These techniques can provide effective safeguards when the single antenna hypothesis is satisfied.

Yet apparently, spoofing signals can potentially be transmitted from distributed directions, with multiple antennas each transmitting a single signal. We call it distributed GNSS spoofing. Intuitively, distributed GNSS spoofing is likely to disable the above spatial-characteristic-based anti-spoofing techniques. However, it is hard to verify the above inference. Up to now as far as we know, distributed GNSS spoofing threat remains a theoretical possibility and has not been validated by any published literature.

To validate the distributed GNSS spoofing threat and supplement a new GNSS security assessment instrument, we develop a spoofer for distributed GNSS spoofing using FPGA platform. It can generate spoofing signals from a maximum of eight independent output ports. With our spoofer, we construct an experiment platform to explore the influence of distributed GNSS spoofing. We will present the experiment results and analysis from the following three aspects.

1) Testing and validating the fundamental operation of distributed GNSS spoofing in an indoor environment.

2) Implementing drift-off spoofing using the distributed GNSS spoofing structure in an open-sky environment.

3) Performance of representative spatial-characteristic-based anti-spoofing techniques against distributed GNSS spoofing.

To summarize, our work verifies the feasibility of distributed GNSS spoofing, reveals the limitation of spatial-characteristic-based anti-spoofing techniques, and urges for more sophisticated anti-spoofing techniques.