Wireless Synchronization Signal Detection Using Adaptive Two-Stage Correlation
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Solution Overview
Problem
Current synchronization techniques in wireless communications face increased computational burden due to the need to search across multiple time and frequency offsets, leading to inefficiencies and potential false alarms, especially in environments with frequency errors and low signal-to-noise ratios.
Innovation Solution
A two-stage synchronization method is employed, where differential decoding is initially used to reduce the need for frequency dimension searching, and if the results are unreliable, classical coherent detection is applied across both time and frequency offsets, ensuring optimal detection performance regardless of signal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If classical coherent detection is used to detect synchronization signals across multiple time and frequency offsets, then detection reliability is improved, but computational complexity increases significantly
Solution Approach 1:
The patent segments the synchronization detection process into two distinct stages: a first stage using differential decoding to quickly eliminate obvious false alarms, and a second stage using classical coherent detection only when needed. This segmentation allows the system to achieve reliable detection while significantly reducing the overall computational burden by avoiding exhaustive frequency offset searches in most cases.
Solution Approach 2:
The patent implements a dynamic two-stage detection approach where the detection method adapts based on signal conditions. The first stage uses differential decoding which is computationally efficient and works well under most conditions. Only when the first stage results are unreliable does the system transition to the more computationally intensive second stage with classical coherent detection, making the detection process dynamic and condition-dependent.
2Measurement precision
If exhaustive frequency offset searching is performed during synchronization, then frequency synchronization accuracy is improved, but processing time increases
Solution Approach 1:
The patent applies preliminary action by performing differential decoding in the first stage to quickly identify and eliminate false alarm time offsets before committing to the time-consuming frequency offset search. This preliminary filtering action significantly reduces the search space for the subsequent coherent detection stage, thereby reducing overall processing time while maintaining frequency synchronization accuracy.
3Measurement precision
If multiple frequency offset hypotheses are tested during correlation, then frequency offset detection accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent segments the energy-consuming detection process into two stages with different energy profiles. The first stage using differential decoding consumes minimal energy and eliminates most false alarms quickly. The second stage with multiple frequency offset hypotheses is executed only when necessary, significantly reducing overall energy consumption while maintaining frequency offset detection accuracy when needed.
4Device complexity
If differential decoding is used to reduce computational burden, then false alarm probability increases in low signal-to-noise ratio conditions
Solution Approach 1:
The patent segments the detection process so that differential decoding is used only in the first stage for initial filtering, not for final detection decisions. This segmentation allows the system to benefit from the low computational complexity of differential decoding while limiting its use to scenarios where it is appropriate, then transitioning to more reliable methods when signal conditions deteriorate.
Solution Approach 2:
The patent implements feedback by evaluating the reliability of first-stage detection results and using this feedback to determine whether to proceed to the second stage. When the first stage results show high false alarm probability (indicating low signal-to-noise ratio conditions), the feedback mechanism triggers the second stage with classical coherent detection, thereby adapting the detection strategy based on observed performance.
Data Source
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AI summary
A wireless device detects a synchronization signal by obtaining (210), from a received signal, a sequence of samples, and calculating (220) a differentially decoded sequence from the obtained sequence of samples. The wireless device correlates (230) the calculated differentially decoded sequence with a first reference sequence corresponding to the synchronization signal, at each of a plurality of time offsets, and identifies which of the plurality of time offsets results in a largest correlation result. In response to determining (240) that the largest correlation result does not meet a predetermined reliability criterion, the wireless device correlates (250) the obtained sequence of samples with a second reference sequence, at each of a plurality of time and frequency offsets, and identifies which combination of time offset and frequency offset results in a largest correlation result. The first reference sequence comprises a differentially decoded version of the second reference sequence.