Cell Search Subcarrier Power Segmentation
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Solution Overview
Problem
Conventional cell search methods in wireless communication systems employing the OFDMA scheme require excessive calculation and time due to the need to correlate all PN sequences with the preamble signal, making the process inefficient.
Innovation Solution
A cell search apparatus and method that calculates subcarrier power in the frequency domain to identify the segment a subscriber station belongs to, and then correlates only a predetermined number of PN sequences corresponding to that segment, reducing the number of calculations required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all PN sequences are correlated with the preamble signal to identify cell segment, then the cell search accuracy is maintained, but the calculation complexity and time consumption increase significantly
Solution Approach 1:
The patent segments the cell search process into two distinct phases: first identifying the cell ID through correlation with all 96 PN sequences, then identifying the cell segment by correlating only 32 specific PN sequences corresponding to the identified cell ID. This segmentation reduces the total number of correlation operations from 96 to 128 (96 for cell ID + 32 for segment), compared to the conventional method requiring 96 correlations for every possible segment across all cells.
Solution Approach 2:
The patent performs preliminary identification of the cell ID before proceeding to segment identification. By first determining which cell the subscriber station belongs to, the system can then pre-select and correlate only the relevant 32 PN sequences associated with that specific cell, rather than performing exhaustive correlations with all possible segment sequences.
2Measurement precision
If all PN sequences are correlated with the preamble signal to identify cell segment, then the cell search accuracy is maintained, but the time consumption increases
Solution Approach 1:
The patent segments the cell search process into two distinct phases: first identifying the cell ID through correlation with all 96 PN sequences, then identifying the cell segment by correlating only 32 specific PN sequences corresponding to the identified cell ID. This segmentation reduces the total number of correlation operations from 96 to 128 (96 for cell ID + 32 for segment), compared to the conventional method requiring 96 correlations for every possible segment across all cells.
Solution Approach 2:
The patent performs preliminary identification of the cell ID before proceeding to segment identification. By first determining which cell the subscriber station belongs to, the system can then pre-select and correlate only the relevant 32 PN sequences associated with that specific cell, rather than performing exhaustive correlations with all possible segment sequences.
3Productivity
If subcarrier power calculation is used to identify cell segment, then the calculation time is reduced, but the method complexity increases
Solution Approach 1:
The patent introduces subcarrier power calculation as an intermediary step that bridges the received preamble signal and the final segment identification. By calculating the power of each subcarrier and comparing it against threshold values, the system obtains an intermediate result (power comparison outcome) that directly indicates the cell segment, avoiding the need for exhaustive PN sequence correlations.
Data Source
AI summary
Disclosed is an apparatus and a method for performing a cell search in a wireless communication system. A subscriber station calculates the power of subcarriers according to their positions in a preamble signal of a frequency domain and identifies a segment of a cell to which the subscriber station belongs. Then, the subscriber station correlates PN sequences, which correspond to the segment of the cell that has been identified, with the preamble signal of the frequency domain. Therefore, the number of calculations for determining correlation values in a cell search is remarkably reduced.