Page 59 - EETimes Europe June 2021

EE|Times EUROPE 59

OPINION | GPS/GNSS education, policies, standards, and guidance
needed to increase PNT resilience.
System and device testing to gauge their
Need for Resilient PNT ability to withstand interference has become
important, shedding light on whether, and
Has Never Been Greater how well, they can perform as expected when
there is disruption or denial of GNSS services.
Testing also uncovers the consequences when
performance is compromised. It is an essen-
By Guy Buesnel, Spirent Communications tial part of any risk assessment.

MITIGATION TECHNOLOGIES
REAL-WORLD INSTANCES of Global Navigation Satellite Cost-effective mitigation should adopt the
System (GNSS) jamming and spoofing have been steadily increasing system-of-systems approach encouraged by
in recent years. High-profile incidents include spoofing attacks on both U.K. and U.S. policymakers. This means
hundreds of commercial ships in the Black Sea and repeated GNSS looking beyond GNSS device resilience to
jamming affecting commercial aviation in Norway. ensure operational procedures are in place
During 2019 alone, pilots reported more than 3,500 instances of to cover situations when GNSS is disrupted
GPS jamming, air traffic management organization or denied. Where necessary, mitigation also
Eurocontrol recently disclosed. involves augmenting or complementing the
In the U.S., the Federal Communications Commission has con- precise positioning and timing data from
ditionally approved an application by satellite communications provider Ligado Networks to GNSS with information from other sensors.
deploy a low-power terrestrial nationwide network in the L-band to support 5G and IoT services. Hardening existing GNSS systems could
The decision means that GNSS systems and devices must be capable of resisting adjacent-band include improving antenna technology and
radio-frequency interference at extremely high power levels while still providing extremely investing in multi-constellation, multi-
accurate and precise data to users. frequency GNSS receivers. Alternative or
Meanwhile, most, if not all, of the major GNSS providers are experiencing space, control, and complementary PNT sources must also be
user-segment issues. The transmitted data from satellites can contain errors or be corrupted to considered, including the use of improved
such an extent that it becomes practically unusable. holdover technologies for timing and the
There is little doubt that users of GNSS positioning and timing data will be dealing with a use of additional terrestrial or space-based
growing spectrum of threats to their services. While the weak power of GNSS signals remains a positioning and timing services as they
fundamental issue for users on the ground, overdependence is another concern. become available.
GNSS has become an “invisible utility,” its use deeply embedded in our society. We often rely Examples include time over fiber, enhanced
on GNSS to obtain precise timing or positioning data for the operation of key elements of our long-range navigation (eLORAN), and broader
critical national infrastructures. In many cases, the dependencies and reliance on GNSS-derived use of low Earth orbit (LEO) satellite net-
data are not fully understood; in some cases, they are not even identified. All of this leaves vital works, along with the use of inertial or dead-
services extremely vulnerable to any disruption or denial of GNSS signals. reckoning technology for dynamic platforms.
All of these solutions offer improved resilience
IDENTIFYING DEPENDENCIES or robustness when implemented properly.
European and U.S. policymakers have recognized the dependence of critical national infrastruc- Improving the resilience of our GNSS-
ture on GNSS signals, along with the vulnerability of such systems to GNSS disruption or denial. dependent infrastructure is no longer
In the U.S., “father of GPS” Bradford Parkinson has proposed a “Protect, Toughen, optional; the rising incidence of real-world
Augment” framework for GNSS. This triad encourages a systems-level, multi-strand approach to threats makes it essential. Improving GNSS
improving the situation when using position, navigation, and timing (PNT) data. resilience and solving dependencies based on
Elsewhere, the U.K. government commissioned a review of GNSS dependencies on quantifiable evidence will help ensure a safer
satellite-derived time and position. The review recommended several measures to improve the world driven by precise and reliable use of
resilience of U.K. systems. PNT services.
A key aim of the U.K. report was to ensure PNT resilience at the point of use, not to prescribe This is not an unsolvable problem. We just
technology solutions. Again, the study strongly advocates a system-of-systems approach to need to act. ■
boosting PNT resilience.
Both approaches make clear there is no silver-bullet solution to our GNSS dilemma. Rather, Guy Buesnel is a PNT security technologist at
there needs to be a well-coordinated approach to the problem that provides users with the Spirent Communications.

IMAGE: SHUTTERSTOCK

www.eetimes.eu | JUNE 2021