OVSF Code Estimation via Power Variance Normalization
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Solution Overview
Problem
In WCDMA communication systems, accurately estimating orthogonal variable spreading factor (OVSF) codes without causing abnormal operations is challenging, especially when relying on connection information extraction methods that may introduce further errors.
Innovation Solution
The method estimates OVSF codes based on the power variance of reception symbols using a candidate OVSF code, without requiring a reference value for zero crossing rate (ZCR), by dechannelizing the signal and normalizing power variance, allowing for accurate estimation without the need for reference value setting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If connection information is extracted from upper layer signals or user input, then the terminal can acquire connection information, but abnormal operations may occur due to errors in extraction
Solution Approach 1:
The patent replaces the mechanical/manual method of extracting connection information from upper layer signals or user input with an automated signal processing system. The system uses dechannelizing based on candidate OVSF codes followed by power variance calculation to automatically estimate connection information, eliminating manual intervention and reducing extraction errors that cause abnormal operations.
Solution Approach 2:
The terminal performs self-diagnosis and self-estimation of connection information by processing its own reception signals. Through automatic dechannelizing and power variance analysis, the terminal can independently acquire connection information without relying on external user input or potentially error-prone upper layer signal extraction, thereby improving both reliability and precision.
2Ease of operation
If reference value setting is used for OVSF code estimation, then the estimation process can be simplified, but errors occur due to reference value setting requirements
Solution Approach 1:
The patent extracts and eliminates the problematic reference value setting step from the OVSF code estimation process. By using power variance calculation on dechannelized signals, the system directly estimates OVSF codes without requiring external reference values, thereby removing the source of estimation errors while keeping the process straightforward.
Solution Approach 2:
The patent introduces power variance as an intermediary metric between the received signal and the final OVSF code estimation. Instead of directly comparing signals against reference values, the system calculates power variance of dechannelized signals as an intermediate step, which naturally leads to accurate estimation without requiring manual reference value setting.
3Measurement precision
If power variance of reception symbol is used for OVSF code estimation, then estimation accuracy is improved, but the process becomes more complex
Solution Approach 1:
The patent segments the OVSF code estimation process into distinct, manageable stages: first dechannelizing the received signal using candidate OVSF codes, then calculating power variance of the dechannelized symbols, and finally determining the estimated code based on variance comparison. This segmentation makes the complex process systematic and implementable through standard signal processing blocks.
Solution Approach 2:
The patent performs preliminary dechannelizing of the received signal using candidate OVSF codes before calculating power variance. This preliminary action prepares the signal in advance, transforming it into a form where power variance can be effectively calculated, thereby simplifying the overall estimation process while maintaining high accuracy.
Data Source
AI summary
The present disclosure provides a method for estimating OVSF (orthogonal variable spreading factor) code, the method comprises setting an initial value of a spreading factor and an initial value of an index of the spreading factor; extracting a first reception symbol by dechannelizing a reception signal based on a candidate OVSF code corresponding to the set spreading factor and the set index; acquiring a first code domain power of the first reception symbol; acquiring, if the first code domain power is greater than or equal to a predetermined reference value, variance of power of the first reception symbol which is normalized by the first code domain power; and estimating a used OVSF code based on the variance of the normalized power of the first reception symbol.