TY - CHAP

T1 - Towards Integrity Monitoring for GNSS-Based Time Synchronization in Technical Applications

AU - Lin, Qianwen

AU - Su, Jingyao

AU - Schön, Steffen

PY - 2024/10

Y1 - 2024/10

N2 - Due to the high-accurate and long-term stable atomic clocks onboard the satellites, Global Navigation Satellite System (GNSS) timing is nowadays playing a key role in many applications of time and frequency transmission. Important examples include the synchronization of telecommunications, transportation and multi-sensor systems. The accuracy of synchronization is the primary requirement in these fields, e.g., the financial markets require a range of microseconds for the bank transfer, while the fifth generation of mobile communication (5G) necessitates nanosecond-level synchronization between base stations for temporal coordination and control. As significantly stringent demands are emerging, it can be foreseen that the security aspect is becoming critical. Integrity is the relevant metric defined in navigation performance, which is monitored by well-developed approaches in aviation navigation. However, little attention has been paid to integrity monitoring for critical timing applications. The integrity concepts for the timing service are yet to be explored.In this paper, we aim to develop integrity concepts for GNSS timing service: a) we propose definitions of integrity and continuity for time users, and formulations of corresponding measures for integrity monitoring, e.g., the timing protection level. It is computed as the standard deviation of a Gaussian distribution that can overbound the uncertainty in the clock offset estimates multiplied with a factor determined from the integrity risk requirement. The hardware delays at the receiver end, one of the error sources of the pseudorange measurements, is especially evaluated; b) we review industrial standards and regulations, and indicate critical integrity-relevant parameters, e.g., the alert limit, in representative applications; c) we investigate the feasibility of the proposed integrity measures through real data experiments. We evaluate the availability performance of dedicated estimation methods and suggest their applicability based on the requirements of respective sectors.

AB - Due to the high-accurate and long-term stable atomic clocks onboard the satellites, Global Navigation Satellite System (GNSS) timing is nowadays playing a key role in many applications of time and frequency transmission. Important examples include the synchronization of telecommunications, transportation and multi-sensor systems. The accuracy of synchronization is the primary requirement in these fields, e.g., the financial markets require a range of microseconds for the bank transfer, while the fifth generation of mobile communication (5G) necessitates nanosecond-level synchronization between base stations for temporal coordination and control. As significantly stringent demands are emerging, it can be foreseen that the security aspect is becoming critical. Integrity is the relevant metric defined in navigation performance, which is monitored by well-developed approaches in aviation navigation. However, little attention has been paid to integrity monitoring for critical timing applications. The integrity concepts for the timing service are yet to be explored.In this paper, we aim to develop integrity concepts for GNSS timing service: a) we propose definitions of integrity and continuity for time users, and formulations of corresponding measures for integrity monitoring, e.g., the timing protection level. It is computed as the standard deviation of a Gaussian distribution that can overbound the uncertainty in the clock offset estimates multiplied with a factor determined from the integrity risk requirement. The hardware delays at the receiver end, one of the error sources of the pseudorange measurements, is especially evaluated; b) we review industrial standards and regulations, and indicate critical integrity-relevant parameters, e.g., the alert limit, in representative applications; c) we investigate the feasibility of the proposed integrity measures through real data experiments. We evaluate the availability performance of dedicated estimation methods and suggest their applicability based on the requirements of respective sectors.

KW - GNSS time synchronization

KW - integrity

U2 - 10.33012

DO - 10.33012

M3 - Conference abstract

BT - European Navigation Conference 2024

T2 - 37nd International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GNSS+ 2024

Y2 - 16 September 2024 through 20 September 2024

ER -