UWB Receiver Phase Comparison for Angle-of-Incidence Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing UWB communication systems face challenges in accurately determining the angle of incidence of RF signals due to channel-induced noise and inefficient power consumption, particularly in compact devices like RFID tags, and suboptimal carrier and timing recovery techniques.
Innovation Solution
The proposed UWB receiver employs a ternary ADC for improved signal processing, a carrier recovery mechanism with gear shifting and phase rotation optimization, and a timing recovery loop with early-late gating, along with a method to calculate the angle of incidence using phase differences between antennas spaced apart by more than one wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If antennas are spaced apart by more than one wavelength to improve angle of incidence determination accuracy, then measurement precision improves, but device volume increases
Solution Approach 1:
The patent transitions from considering only spatial separation (one-dimensional approach) to utilizing both spatial and temporal dimensions. By measuring phase differences at multiple frequencies and combining them with time-of-arrival measurements, the system achieves accurate angle determination without requiring large antenna separations, thus resolving the contradiction between measurement precision and device volume.
Solution Approach 2:
The patent changes the operating parameters by utilizing multiple frequencies rather than a single frequency. By measuring phase differences at different frequencies and combining these measurements with time-of-arrival data, the system achieves accurate angle of incidence determination without requiring antennas to be spaced more than one wavelength apart, thereby maintaining compact device volume while improving measurement precision.
2Reliability
If complex channel estimation and matched filtering are applied to reduce noise, then signal-to-noise ratio improves, but power consumption increases
Solution Approach 1:
The patent applies partial channel estimation only during the preamble portion of the signal rather than continuously processing the entire signal. The matched filtering is applied selectively to correlate the received preamble with the expected channel response, achieving sufficient noise reduction for reliable synchronization and angle measurement without the continuous power consumption of full-signal processing.
Solution Approach 2:
The channel estimation and matched filtering operations are performed periodically only during preamble reception intervals rather than continuously. This periodic processing approach allows the system to achieve necessary signal-to-noise ratio improvement for synchronization and initial angle measurement while significantly reducing overall power consumption compared to continuous processing.
3Measurement precision
If phase differences between antennas are measured to determine angle of incidence, then angle measurement capability is achieved, but susceptibility to channel-induced noise increases
Solution Approach 1:
The patent introduces time-of-arrival measurements as an intermediary element that works in conjunction with phase difference measurements. By combining TOA information with phase difference data from multiple frequencies, the system creates a more robust estimation process that is less susceptible to channel-induced noise, as the multiple independent measurements can be combined to average out noise effects.
Solution Approach 2:
The patent employs iterative refinement where initial angle estimates from phase differences are used to guide subsequent measurements and calculations. The system uses feedback from multiple frequency measurements and time-of-arrival data to continuously refine the angle of incidence estimate, reducing the impact of channel-induced noise through cumulative evidence from multiple independent measurements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of angle of incidence determination while reducing power consumption and circuit complexity, providing performance comparable to prior art techniques but with improved efficiency.
Implementation Method 1
calculate the angle of incidence using phase differences between antennas spaced apart by more than one wavelength
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
In an ultra-wideband ("UWB") receiver, a received UWB signal is periodically digitized as a series of ternary samples. During a carrier acquisition mode of operation, the samples are continuously correlated with a predetermined preamble sequence to develop a correlation value. When the value exceeds a predetermined threshold, indicating that the preamble sequence is being received, estimates of the channel impulse response ("CIR") are developed. When a start-of-frame delimiter ("SFD") is detected, the best CIR estimate is provided to a channel matched filter ("CMF"). During a data recovery mode of operation, the CMF filters channel-injected noise from the sample stream. Both carrier phase errors and data timing errors are continuously detected and corrected during both the carrier acquisition and data recovery modes of operation. The phase of the carrier can be determined by accumulating the correlator output before it is rotated by the carrier correction. By comparing the carrier phases of two receivers separated by a known distance, d, the angle of incidence, Θ, of the signal can be determined.