Receiver Time-Tracking Detection Range Extension
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Solution Overview
Problem
In OFDM-based single-frequency networks, the limited detection range of the time-tracking algorithm due to cross-correlation with a preamble symbol restricts the reliable detection of channel delay taps outside the ± FFT_SIZE/2 range, leading to ambiguity and potential misinterpretation of signal contributions, especially in mobile environments where attenuation and fading are significant.
Innovation Solution
The method involves performing multiple cross-correlations of the received signal with a known preamble sequence, dividing the results into delay segments, and comparing the segments from different cross-correlation results to determine the delay, effectively extending the detection range by resolving ambiguity through magnitude comparison between time-shifted cross-correlation results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single cross-correlation with a preamble symbol is used for time tracking, then the algorithm complexity is low and operation is simple, but the detection range is limited to ± FFT_SIZE/2 causing ambiguity for delay taps outside this range
Solution Approach 1:
The patent divides the detection range into multiple segments by performing multiple cross-correlations with different time shifts (e.g., first cross-correlation with shift 0, second cross-correlation with shift FFT_SIZE/2). Each cross-correlation covers a specific segment of the delay range, and the results are combined to achieve extended detection range of ± FFT_SIZE without excessive complexity increase
Solution Approach 2:
The patent extends the detection range by introducing a time-shift dimension. Instead of a single cross-correlation in one dimension, multiple cross-correlations are performed with different time shifts, effectively adding a temporal dimension to the detection process. This allows the system to resolve ambiguities by comparing results across different time-shifted correlations
2Measurement precision
If the detection range is extended beyond ± FFT_SIZE/2, then more delay taps can be detected, but ambiguity increases and reliable detection becomes difficult
Solution Approach 1:
By segmenting the detection range into multiple zones covered by different time-shifted cross-correlations, each segment maintains reliable detection within its own range. The first cross-correlation reliably detects delays in one segment, while the second cross-correlation with time shift reliably detects delays in another segment, collectively covering a wider range without sacrificing reliability in any specific segment
Solution Approach 2:
The patent uses feedback by comparing the results of multiple cross-correlations. The magnitude comparisons between different cross-correlation results provide feedback to determine which delay tap is the strongest and most reliable, allowing the system to resolve ambiguities and maintain detection reliability across the extended range
3Reliability
If multiple cross-correlations are performed to extend detection range, then detection reliability improves, but computational complexity and processing time increase
Solution Approach 1:
The detection process is segmented into multiple parallel cross-correlation operations that can be efficiently implemented using FFT-based methods. By dividing the work into segments (different time-shifted correlations) and processing them systematically, the computational complexity is managed while achieving improved reliability through comparison of results
Solution Approach 2:
The patent changes the time-shift parameter of the cross-correlation to extend detection range. By systematically varying this parameter (e.g., 0, FFT_SIZE/2, FFT_SIZE), the system achieves extended detection capability. The use of efficient algorithms for computing cross-correlations with different shifts minimizes the productivity impact while maintaining reliability improvements
Data Source
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AI summary
A receiver component and a method for enhancing a detection range of a time synchronization process in a receiver utilize multiple cross-correlations of a received signal with a known preamble sequence. The results of the multiple cross-correlations are divided into delay segments. The delay segments of one of the multiple cross-correlations are compared with the delay segments of another of the multiple cross-correlations to determine delay of the delay segments of the one of the multiple cross-correlation results.