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Time Synchronization with Nanosecond Accuracy

Pourishaban Najafabadi, Mozhde | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58214 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Fotowat Ahmady, Ali
  7. Abstract:
  8. In today’s world, where reliance on distributed systems and wireless networks is rapidly expanding, precise time synchronization is recognized as one of the fundamental pillars for the correct operation of such systems. This thesis investigates and develops a nanosecond-level time synchronization system with a focus on autonomous vehicles within the Internet of Things (IoT) framework. The core innovation of this research lies in introducing a GPS-independent approach for accurate time synchronization in mobile wireless networks, leveraging the concept of the "Time of Day" clock. The proposed system is evaluated through simulations in the OMNeT++ environment and hardware implementation on an FPGA. The need for an alternative solution to GPS in challenging environments—such as mountainous roads, deep valleys, or urban areas with tall buildings where GPS signals are limited or unavailable—is a critical issue in the domain of autonomous vehicles. Under such conditions, a reliable protocol capable of compensating for GPS unavailability while providing accurate time synchronization and sub-meter distance estimation becomes indispensable. The proposed architecture achieves high accuracy by allocating time frames to nodes, transmitting time-stamped data, calculating and compensating for propagation delays and timing errors, and implementing time-rounding and internal synchronization algorithms at the node level. Simulation results under both static and mobile node scenarios demonstrate that, even in the absence of GPS signals, time synchronization accuracy better than 5 nanoseconds and distance estimation accuracy better than one meter are achieved. These results indicate that the proposed method not only compensates for the lack of GPS but also, in many scenarios, outperforms GPS-based methods in terms of synchronization accuracy. This work also presents fundamental system-level analyses to understand the limitations of achievable accuracy. Furthermore, results from hardware implementation using NRF24L01+ modules and a ZYNQ7000 processor reveal that a synchronization accuracy of 78.3 nanoseconds has been achieved. This represents a significant improvement over previous studies, which typically report accuracies in the range of 111 to 190 nanoseconds, highlighting enhanced synchronization precision and reduced timing error
  9. Keywords:
  10. Time Synchronization ; OMNet++ Simulator ; Global Position System (GPS) ; Autonomous Vehicles (AVs) ; Field Programmable Gate Array (FPGA) ; Internet of Things ; Nanosecond Accuracy ; NRF24L01+ Modules

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