Mobile Terminal Initial Synchronization via Cell Search Verification
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Solution Overview
Problem
In OFDMA mobile communication systems, terminals face challenges in accurately acquiring initial synchronization due to high false alarm rates and inter-symbol interference, caused by the auto-correlation characteristics of pilot signals, leading to incorrect symbol start point detection and impaired signal recovery.
Innovation Solution
An apparatus and method that utilize an auto-correlator to calculate auto-correlation values of a preamble signal, a peak value detecting unit to average and detect peaks, a cell searching unit to perform cell searches, a regularizing unit to regulate peak values, and a reference value comparing unit to verify synchronization, reducing false alarms by comparing results with a predetermined reference value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the terminal uses auto-correlation characteristic of the preamble signal to acquire initial synchronization, then the terminal can detect the symbol start point, but the auto-correlation characteristic of the pilot signal generates false alarm rates leading to incorrect detection
Solution Approach 1:
The patent introduces a verification mechanism using cell search results as an intermediary to validate the symbol start point detection. The cell search unit performs a separate verification process by checking whether the detected start point aligns with the cell structure, acting as a mediator to filter out false alarms from the auto-correlation-based detection
Solution Approach 2:
The patent implements a feedback loop where the cell search unit continuously verifies the symbol start point detection results. When false alarms occur, the feedback mechanism uses the cell search verification to identify and correct incorrect detections, improving the overall reliability of the synchronization acquisition
2Productivity
If the terminal detects symbol start point using auto-correlation of preamble signal, then synchronization can be acquired, but inter-symbol interference occurs due to wrong symbol start point
Solution Approach 1:
The patent performs cell search verification as a preliminary action before finalizing the symbol start point detection. By预先 checking the detected start point against cell structure requirements, the system prevents wrong detections that would lead to inter-symbol interference, while still maintaining fast synchronization acquisition
3Stability of the object's composition
If the pilot signal pattern is repeated in data field, then the signal structure is maintained, but auto-correlation characteristic is greatly generated causing detection errors
Solution Approach 1:
The patent segments the detection process into two independent parts: auto-correlation-based initial detection and cell search-based verification. This segmentation allows the pilot signal pattern to maintain its structure for signal stability while the separate verification segment prevents detection errors caused by its auto-correlation characteristics
Data Source
AI summary
The present invention relates to an apparatus and method of acquiring initial synchronization of a terminal in a mobile communication system. According to an exemplary embodiment of the present invention, one or more auto-correlation values of a preamble constituting a signal that is received from a base station are calculated. Averages of the calculated auto-correlation values according to samples are calculated, and then a peak value is detected among the calculated values. Then, a cell search is performed on the basis of the detected peak value, and a peak value from the result of the cell search is regularized. Then, the regularized peak value is compared with a predetermined reference value such that it is checked whether synchronization of a signal that has been searched is accurate or not. According to an exemplary embodiment of the present invention, a value obtained by regularizing a result of a cell search is compared with a reference value, and it is checked again whether an accurate start point of a frame is detected or not on the basis of a result of the comparison. Accordingly, false alarm rates can be reduced.