Double-Differential RTT Measurement for Precise UE Positioning

The patent segments the RTT measurement process into multiple independent differential RTT measurements between different wireless nodes (first differential RTT between first and second wireless nodes, second differential RTT between third and fourth wireless nodes). Each measurement is triggered independently by specific events, allowing the system to accumulate multiple measurement samples that can be processed separately to improve overall positioning accuracy while maintaining manageable complexity through modular measurement units.

The patent transitions from single-point RTT measurement to multi-dimensional RTT measurement by introducing measurements between multiple pairs of wireless nodes in different spatial locations. The first differential RTT measurement involves nodes at different positions, and the second differential RTT measurement involves additional nodes, creating a multi-dimensional measurement space that enables more accurate positioning through geometric relationships between multiple measurement points.

The patent implements periodic triggering of differential RTT measurements based on specific events. The first differential RTT measurement is triggered in response to a first triggering event (such as UE movement detection or positioning request), and the second differential RTT measurement is triggered in response to a second triggering event. This event-driven periodic measurement approach ensures measurements are taken at optimal moments without continuous measurement overhead, balancing accuracy improvement with time efficiency.

The system performs preliminary calibration of wireless nodes before positioning measurements are taken. The first wireless node and second wireless node are calibrated using known location data, and the third and fourth wireless nodes are calibrated separately. This preliminary calibration establishes reference timing parameters that enable accurate differential RTT measurements to be taken subsequently without requiring repeated calibration, reducing overall measurement time while maintaining high accuracy.

The patent implements self-service calibration where the first wireless node and second wireless node perform hardware group delay calibration using their own known locations and the measured RTT values. The calibration parameters are computed automatically based on the calibration data without requiring external intervention. Similarly, the third and fourth wireless nodes perform independent calibration. This self-service approach eliminates the need for complex external calibration equipment while achieving high timing measurement precision through automated parameter computation.

The patent adjusts timing parameters dynamically based on calibration results. After obtaining RTT measurements and processing calibration data, the system computes calibration parameters (such as hardware group delay values) and uses these to adjust the timing measurements. The parameter adjustment is performed through mathematical computations on the calibration data, transforming raw RTT measurements into corrected timing values that account for hardware delays, thereby improving precision without requiring physical hardware modifications.