Mobile Clock Estimation Using Position and Velocity Assistance
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Solution Overview
Problem
Maintaining timing accuracy in wireless computing devices is challenging in environments where Satellite Positioning System (SPS) and network signals are unavailable or of limited availability, which is crucial for strict time synchronization requirements in communication protocols like C-V2X.
Innovation Solution
Utilizing position and velocity estimates from sensors and range estimates from external timing information sources, such as SPS satellites or pseudolites, to adjust the clock of wireless devices and maintain synchronization, even in SPS-challenged or network-challenged environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SPS and network signals are used to provide reference clock for time synchronization, then timing accuracy is improved, but reliability deteriorates in areas with unavailable signal coverage
Solution Approach 1:
The patent introduces an intermediary system consisting of pseudolites (ground-based SPS simulators) and V2V communication between vehicles to mediate clock synchronization. When satellite signals are unavailable, vehicles use pseudolite signals combined with velocity information from V2V communication to estimate and correct clock drift, maintaining synchronization reliability without direct satellite dependency
Solution Approach 2:
The system enables vehicles to self-correct their clock drift using their own velocity information obtained from V2V communication. Each vehicle independently calculates its clock parameters based on its velocity and pseudolite range measurements, eliminating the need for continuous external satellite timing references and maintaining autonomous time synchronization capability
2Measurement precision
If clocks rely on SPS and network signals to remain in sync, then timing accuracy is maintained, but adaptability deteriorates in SPS-challenged or network-challenged environments
Solution Approach 1:
The patent implements a dynamic clock correction system that adapts to different environmental conditions. The system continuously monitors signal availability and dynamically switches between SPS-based correction and pseudolite/V2V-based correction modes. Velocity information from V2V communication is dynamically integrated to estimate clock drift in challenging environments, enabling the system to maintain adaptability across diverse operational scenarios
Solution Approach 2:
The system changes the parameters used for clock correction based on environmental conditions. When SPS signals are available, it uses satellite-based timing parameters; when unavailable, it transitions to using pseudolite range parameters combined with velocity parameters from V2V communication. This parameter substitution enables the system to adapt to SPS-challenged and network-challenged environments while maintaining timing accuracy
3Reliability
If position and velocity information from V2X is used to estimate clock parameters, then reliability is improved in limited coverage areas, but device complexity increases
Solution Approach 1:
The system performs preliminary acquisition of velocity information through V2V communication before it is needed for clock correction. By obtaining velocity data in advance from neighboring vehicles and storing it for later use in clock parameter estimation, the system reduces real-time processing complexity while maintaining reliability in signal-denied environments
Data Source
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AI summary
A method for maintaining timing accuracy in a mobile device includes: obtaining a range estimate using a signal received from a timing information source via a communication unit of the mobile device (905); obtaining position and velocity estimate information for the mobile device from a source of position and velocity information separate from the timing information source, the position and velocity estimate information being obtained from at least one sensor of the mobile device, or via a communication unit of the mobile device using a Vehicle-to-Everything wireless communication protocol, or a combination thereof (910); determining estimated clock parameters based on the position and velocity estimate information and the range estimate (915); and adjusting a clock of the mobile device based on the estimated clock parameters in response to a position-and- velocity-assisted timing uncertainty corresponding to the estimated clock parameters being below a timing uncertainty threshold (920).