OFDM TDOA Measurement via Oversampled Correlation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing TDOA methods in communication networks, particularly in 4G and 5G wireless systems, face significant challenges in achieving high-accuracy positioning in indoor environments due to multipath interference and OFDM inter-symbol interference, leading to large errors and unsatisfactory positioning accuracy.
Innovation Solution
A method and apparatus for measuring the time difference of arrival (TDOA) of a first arrival path using an orthogonal frequency division multiplexing (OFDM) signal system, which involves acquiring OFDM positioning symbol data, generating a local oversampled signal through interpolation, performing trailing edge detection and leading edge supplementation on the oversampling cyclic correlation function sequence, and estimating the TDOA to improve positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional TDOA methods are used in indoor environments, then positioning can be performed, but positioning accuracy deteriorates due to multipath interference and OFDM inter-symbol interference
Solution Approach 1:
The patent segments the received signal into multiple paths and identifies the first arrival path separately from reflected paths. By dividing the correlation function analysis into distinct path components, the method isolates the direct path signal from multipath interference, enabling accurate TDOA measurement despite indoor environmental challenges
Solution Approach 2:
The patent performs preliminary signal processing including cyclic prefix removal and FFT transformation before correlation analysis. By preprocessing the signal to extract clean OFDM symbol data and generate expected signal sequences in advance, the method prepares the signal in an optimal state for accurate correlation-based TDOA measurement, reducing the impact of interference
2Measurement precision
If conventional TDOA methods are used, then positioning can be performed, but measurement precision deteriorates due to OFDM inter-symbol interference and sampling period limitations
Solution Approach 1:
The patent changes the sampling rate parameter by performing oversampling during correlation analysis. By increasing the sampling density beyond the minimum Nyquist rate, the method captures more signal details and reduces sampling period effects, enabling more precise peak detection in the correlation function and improving TDOA measurement accuracy
Solution Approach 2:
The patent generates a local copy of the expected OFDM signal sequence at the receiving end and correlates it with the received signal. This copying approach creates a reference signal that accounts for known transmission characteristics, allowing the correlation process to extract accurate arrival time information even in the presence of channel distortions and interference
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
Disclosed is a method and apparatus for measuring time difference of arrival (TDOA) of a first arrival path. The method includes: a receiving end acquiring orthogonal frequency division multiplexing (OFDM) positioning symbol data, and generating a local oversampled signal; the receiving end obtaining an oversampling cyclic correlation function sequence through calculation according to the OFDM positioning symbol data and the local oversampled signal, and performing trailing edge detection and leading edge supplementation on the oversampling cyclic correlation function sequence; and the receiving end estimating TDOA of first arrival path based on the oversampling cyclic correlation function sequence subjected to the trailing edge detection and the leading edge supplementation.