Cell Search Time Reduction via Asynchronous Signal Scanning
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Solution Overview
Problem
Conventional cell-search methods in communication terminal units take a long time due to synchronous detection over the entire band range, leading to delayed location registration when a mobile terminal enters or exits a communication range.
Innovation Solution
Implementing asynchronous detection to measure received-signal levels over a predetermined search frequency range, followed by synchronous detection only in frequency ranges where a desired signal exists, reducing the number of frequencies to be searched and thus shortening cell-search time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous detection is implemented over the entire band range at every channel raster, then comprehensive cell detection coverage is achieved, but cell-search time becomes excessively long
Solution Approach 1:
The patent applies preliminary action by performing asynchronous detection across the entire band range before conducting synchronous detection. This preliminary scanning identifies frequency regions with potential cell signals, allowing the subsequent synchronous detection to be focused only on those specific regions rather than the entire band, thereby significantly reducing cell-search time while maintaining detection coverage.
Solution Approach 2:
The patent segments the cell-search process into two distinct phases: asynchronous detection phase that scans the entire band range to identify promising frequency regions, and synchronous detection phase that focuses only on those identified regions. This segmentation divides the originally monolithic time-consuming operation into manageable stages, reducing overall search time while preserving reliability.
2Reliability
If synchronous detection is performed over the entire band range, then no cell signals are missed, but location registration is delayed when entering or exiting communication range
Solution Approach 1:
The patent performs preliminary asynchronous detection to identify frequency regions containing cell signals before executing synchronous detection. This preliminary action ensures that no cell signals are missed (maintaining detection completeness) while focusing subsequent detailed detection only on relevant frequencies, thereby accelerating location registration when terminals enter or exit communication ranges.
Solution Approach 2:
The patent applies local quality by concentrating synchronous detection resources on specific frequency regions identified as having potential cell signals, rather than uniformly applying detection across the entire band. This localized approach maintains detection completeness for actual cell signals while reducing unnecessary detection operations in empty frequency regions, thus improving location registration speed.
3Productivity
If asynchronous detection is used to scan the entire band range, then frequency regions with cell signals can be identified quickly, but synchronous detection must then be performed only on identified regions
Solution Approach 1:
The patent replaces the traditional single-mode synchronous detection mechanism with a two-stage detection system incorporating asynchronous detection. Asynchronous detection uses simpler correlation operations to quickly scan the entire band range and identify promising frequency regions, substituting the more complex and time-consuming synchronous detection for the initial scanning phase, thereby improving overall efficiency.
Data Source
AI summary
In carrying out a cell search, the received-signal level (RSSI) at each frequency is measured in the first place, by implementing asynchronous detection in steps of a predetermined frequency-step width over a predetermined search frequency range (from Fini to Fend), After measuring the RSSI, a cell search is carried out by implementing synchronous-detection processing over the frequency range that has a center frequency where the received-signal level is higher than a threshold value and that has the frequency-step width, it is an object of the present invention to obtain a communication terminal unit that can reduce a cell-search time.