Cell Search Process for Wireless Communication Systems
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Solution Overview
Problem
The standard cell search process in W-CDMA wireless communication systems is time-consuming, requiring significant processing power and energy, and takes several minutes to complete a full band scan, which occupies valuable resources in mobile stations.
Innovation Solution
A method that scans radio channels in increments corresponding to a standard raster, estimates the primary synchronisation code signal-to-noise ratio, and performs a cell search only if the ratio exceeds a threshold, then increases scanning increments to the frequency separation between cells, sorts channels by signal-to-noise ratio, and performs the search in descending order, thereby reducing processing power and time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the standard cell search process is performed on all radio channels, then complete cell identification is achieved, but the time required increases to several minutes
Solution Approach 1:
The patent performs preliminary actions by scanning radio channels with coarse frequency increments first to identify candidate channels containing cell signals. This preliminary scan filters out channels without signals before performing the complete cell search procedure, significantly reducing the total time while maintaining identification completeness.
Solution Approach 2:
The cell search process is segmented into two phases: an initial coarse scan phase that quickly identifies candidate channels, and a subsequent detailed search phase that performs complete cell identification only on those candidates. This segmentation divides the originally monolithic time-consuming process into manageable stages.
2Reliability
If the standard cell search process is performed on all radio channels, then all visible cells are detected, but processing power and energy consumption increase significantly
Solution Approach 1:
The patent performs preliminary channel scanning with simple signal presence detection before committing to energy-intensive cell search operations. This preliminary filtering action prevents wasteful energy expenditure on channels that contain no cell signals, while ensuring that all channels with potential cells are identified for detailed searching.
Solution Approach 2:
The patent performs a partial cell search (coarse scan) on all channels first, then performs the complete cell search (detailed action) only on a subset of candidate channels. This partial action approach reduces overall energy consumption while maintaining complete detection of all visible cells through the subsequent focused detailed search.
3Reliability
If the standard cell search process is performed on all radio channels, then comprehensive cell information is obtained, but the processing time occupies resources needed for other functions
Solution Approach 1:
The patent segments the cell search process into an initial filtering stage that quickly identifies candidate channels, and a subsequent processing stage that performs comprehensive cell analysis only on those candidates. This segmentation prevents the mobile station's processing resources from being continuously occupied, improving overall system productivity.
Solution Approach 2:
The patent performs preliminary channel identification using minimal processing requirements before initiating the resource-intensive complete cell search procedure. This preliminary action prepares the system by identifying only those channels requiring full processing attention, thereby improving processing efficiency without compromising search completeness.
Data Source
AI summary
A method of cell search in a wireless communication systems having a plurality of base stations and a mobile station, each of the plurality of base stations serving a separate cell within a service area and transmitting a common primary synchronization code (PSC) in a primary synchronization channel within a slot of a radio frame, the method including the steps of: (a) scanning (72) through radio channels in scanning increments corresponding to a standard channel raster; (b) estimating (98) the PSC signal-to-noise ratio of each radio channel; (c) if a PSC signal-to-noise ratio is above a first predetermined threshold level (100), completing a cell search procedure including slot synchronization, frame synchronization and scrambling code detection steps for that radio channel; (d) if the cell search procedure is successfully completed (112) for the radio channel in step (c), increasing the scanning increments to the broadcast frequency separation between cells; (e) when all radio channels are scanned in step (d), sorting (74) the scanned radio channels in descending order by PSC signal-to-noise ratio; and (f) performing (76) the cell search procedure on each sorted radio channel in descending order.