Cell Search Device Using Differential Demodulation for Phase Delay Correction
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Solution Overview
Problem
In OFDMA-based cellular systems, existing technologies face challenges in efficiently performing time synchronization, frequency synchronization, and cell search using a single preamble symbol, leading to decreased system performance due to phase delays caused by synchronization errors.
Innovation Solution
A cell search device and method that combines a PN code with a Walsh code, using differential demodulation and synchronization demodulation to estimate phase delays and correct them, allowing for efficient cell identification by calculating correlation values in the frequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single preamble symbol is used for time synchronization, frequency synchronization, and cell search in OFDMA-based cellular systems, then the effective period for real data is increased, but phase synchronization errors occur leading to decreased system performance
Solution Approach 1:
The preamble symbol is segmented into multiple sub-preambles, each carrying different PN codes. This allows the system to perform time synchronization, frequency synchronization, and cell search using multiple correlation peaks from different sub-preambles, thereby maintaining a single preamble structure while improving synchronization accuracy and reducing phase errors.
Solution Approach 2:
The patent introduces a new dimension by combining multiple PN codes within a single preamble symbol structure. Instead of using one PN code, the preamble incorporates multiple PN codes that can be differentiated through correlation processing, enabling enhanced synchronization capabilities without increasing the preamble duration.
2Adaptability or versatility
If multiple PN codes are used for different cells in the preamble, then cell search capability is improved, but the complexity of correlation calculation increases
Solution Approach 1:
The patent performs preliminary action by pre-configuring multiple PN codes within the preamble symbol structure before transmission. The terminal device can then efficiently search for cells by correlating the received preamble with these pre-configured PN codes, reducing the computational complexity during the cell search process.
Solution Approach 2:
The preamble symbol is designed with multi-functionality, serving both time synchronization and cell search purposes simultaneously. By incorporating multiple PN codes that can be differentiated through correlation processing, the same preamble structure performs multiple functions, reducing the need for separate synchronization and cell search procedures.
3Measurement precision
If differential demodulation is used to estimate phase delays, then time synchronization error is reduced, but the processing time for cell search increases
Solution Approach 1:
The patent implements continuous correlation processing between the received preamble and multiple PN codes. By maintaining continuous correlation and differentiation operations throughout the cell search process, the system efficiently estimates phase delays and achieves precise time synchronization without significant processing time penalties.
Solution Approach 2:
The differential demodulation process incorporates feedback mechanisms where the estimated phase delays are continuously refined based on correlation results. This feedback loop allows the system to adjust synchronization parameters in real-time, improving precision while minimizing the overall processing time through iterative refinement.
Data Source
AI summary
A cell search device using an appropriate preamble for a downlink of a cellular system using an orthogonal frequency division multiplexing access (OFDMA) scheme and a method thereof is disclosed. The cell search device for a terminal of a cellular system using an orthogonal frequency division multiplexing access scheme includes when the terminal receives a preamble symbol from a base station, a PN code and phase delay estimating unit for generating a code with the received preamble symbol and a combination of a PN code and a Walsh code, calculating a correlation value therebetween using a differential demodulation for the codes to detect the PN code, a plurality of Walsh codes, and an error of a time delay, and estimating a component of a phase delay for the time delay; and a Walsh code estimating unit for minimizing the influence of the time error using the phase delay and the PN code information obtained by the differential demodulation of the PN code and phase delay estimating unit and estimating a Walsh code for the corresponding cell by synchronization demodulation.