Radio Frequency Scan Acceleration Using Cyclic Prefix Autocorrelation
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Solution Overview
Problem
User equipment devices often take an excessive amount of time to search for and connect to a wireless base station due to the inefficiencies in frequency scanning processes, particularly in 4G and 5G networks, which consume significant processing resources and delay network access.
Innovation Solution
The use of a cyclic prefix autocorrelation property in orthogonal frequency division multiplexing signals to narrow the set of candidate frequencies, enabling rapid symbol boundary timing correction and center frequency offset estimation, thereby reducing the duration of frequency scans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full raster scan over all frequencies is performed to search for a wireless base station, then comprehensive frequency coverage is achieved, but the search time becomes excessively long
Solution Approach 1:
The patent performs preliminary actions by generating autocorrelation metrics and identifying peak locations before the actual frequency search. The UE determines a reduced set of candidate frequencies based on these preliminary autocorrelation results, eliminating the need to scan all frequencies systematically. This preliminary analysis allows the system to focus only on promising frequency regions, dramatically reducing search time while maintaining detection accuracy.
Solution Approach 2:
The patent extracts only the necessary frequency information from the full frequency spectrum by using autocorrelation to identify peak locations. Instead of processing all frequencies in a full raster scan, the system extracts candidate frequencies based on autocorrelation peaks, which correspond to likely base station transmission frequencies. This extraction approach maintains measurement precision while reducing the time required by focusing computation on relevant frequency regions only.
2Loss of time
If autocorrelation-based frequency narrowing is used to reduce candidate frequencies, then search time is reduced, but processing complexity increases
Solution Approach 1:
The patent replaces the mechanical systematic scanning approach with a signal processing-based autocorrelation method. Instead of sequentially tuning through all frequencies in a predetermined raster pattern, the system uses autocorrelation operations on received signals to automatically identify candidate frequencies. This substitution transforms a time-consuming mechanical search into a more efficient computational process that leverages the statistical properties of the received signals.
Solution Approach 2:
The patent changes the processing parameter from systematic frequency tuning to autocorrelation metric calculation. By computing autocorrelation metrics across the frequency spectrum and identifying peak locations, the system transforms the frequency search problem into a peak detection problem. This parameter change enables the use of efficient autocorrelation algorithms that can quickly identify candidate frequencies without requiring exhaustive scanning of all frequency points.
Data Source
AI summary
An electronic device having a radio is provided. When the radio boots up, the radio may search for downlink signals transmitted by a wireless base station. The device may generate a narrow set of candidate frequencies over which to search for the downlink signals by leveraging a cyclic prefix autocorrelation property of the downlink signals. Each candidate frequency may have a corresponding center frequency offset (CFO) and symbol boundary timing correction that is used when searching over the narrow set of candidate frequencies. To generate the narrow set of candidate frequencies, control circuitry may generate autocorrelated signals from baseband-shifted input signals over a set of different center frequencies and bandwidths. Searching over the narrow set of candidate frequencies may be significantly faster than performing a full raster scan over all frequencies supported by the radio.