Frequency Scan Post-Processing Circuit for PLMN Search Optimization
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Solution Overview
Problem
Conventional Public Land Mobile Network (PLMN) search methods in mobile radio communication terminal devices are inefficient due to long frequency scan times and poor quality of frequency scan output, especially when dealing with a high number of Enhanced Universal Mobile Telecommunications System (UMTS) Radio Access (E-UTRA) Absolute Radio Frequency Channel Numbers (EARFCNs), leading to prolonged network attachment times.
Innovation Solution
A post-processing technique that improves the quality of frequency scan output by using local cross-correlation function (CCF) peaks and averaged CCF values to shorten and rank the list of EARFCN candidates, thereby reducing the time required for the entire PLMN search procedure. This involves determining cross-correlation coefficients, forming a CCF metric vector, and selecting only candidates with quality metrics exceeding predefined thresholds for further cell scan processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If RSSI-based frequency scan is used, then frequency scan time is short, but quality of frequency scan output is poor due to vulnerability to interference from other RAT
Solution Approach 1:
The patent introduces an intermediary processing stage between frequency scan and cell scan. The frequency scan post-processing circuit acts as a mediator that filters and ranks frequency candidates using CCF metrics before passing them to the cell scan circuit. This intermediary layer improves output quality without significantly increasing scan time by efficiently processing candidates in descending order of their CCF metric values.
Solution Approach 2:
The patent applies preliminary action by performing frequency scan post-processing before the cell scan procedure. The post-processing circuit calculates CCF metrics and ranks frequency candidates in advance, creating a prioritized list of candidates. This preliminary ranking ensures that the cell scan starts with the most promising frequencies, improving overall search efficiency and output quality.
2Productivity
If conventional frequency scan is used without post-processing, then device complexity is low, but productivity is low due to long PLMN search time
Solution Approach 1:
The patent segments the PLMN search process into distinct functional modules: frequency scan circuit, frequency scan post-processing circuit, and cell scan circuit. Each module has a specific responsibility - the frequency scan circuit performs initial scanning, the post-processing circuit ranks candidates using CCF metrics, and the cell scan circuit performs detailed cell detection. This segmentation improves productivity by enabling optimized processing at each stage while keeping individual module complexities manageable.
Solution Approach 2:
The patent introduces dynamic elements through the post-processing circuit that adaptively ranks frequency candidates based on calculated CCF metrics. The system dynamically determines the order of frequency candidates to be scanned, rather than using a fixed predetermined order. This dynamic adaptation allows the system to prioritize frequencies with higher likelihood of containing valid cells, improving PLMN search speed without requiring excessive hardware complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed method significantly shortens the mobile radio cell scan time and improves the quality of the frequency scan output, accurately detecting empty LTE frequency bands and reducing unnecessary scans, thus enhancing user experience by speeding up network attachment.
Implementation Method 1
determining a plurality of cross-correlation coefficients for a plurality of received digitized signals, forming a cross-correlation coefficient vector including the plurality of cross-correlation coefficients
Data Source
AI summary
A method of processing a plurality of received digitized signals may include determining a plurality of cross-correlation coefficients for the plurality of received digitized signals; forming a cross-correlation coefficient vector including the plurality of cross-correlation coefficients; and determining an evaluation value for at least some of the plurality of cross-correlation coefficients. The determining the evaluation value may include: pre-selecting a predefined number of cross-correlation coefficients from the cross-correlation coefficient vector and deleting the pre-selected number of cross-correlation coefficients from the cross-correlation coefficient vector; after the pre-selection, determining an averaging value using at least one of the non-preselected cross-correlation coefficients of the cross-correlation coefficient vector; and determining the evaluation values based on the respective value of the pre-selected cross-correlation coefficient and the averaging value. The method may further include selecting one or more cross-correlation coefficients based on the determined evaluation values; and further processing based on the selected one or more cross-correlation coefficients.