Receiver Noise Estimation Frequency Error Compensation
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Solution Overview
Problem
Wireless communication receivers face noise estimation errors due to receiver frequency errors, leading to inaccurate signal quality calculations and inappropriate data rate selection in wireless communication networks, resulting in underutilization or unreliable data transmission.
Innovation Solution
A method for improved noise estimation in wireless communication receivers that incorporates an error term based on an estimate of receiver frequency error, generating a compensated noise estimate by removing the frequency error bias, which is used for enhanced signal quality measurements and noise suppression filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If receiver frequency error compensation is not applied in noise estimation processing, then the noise estimation process remains simple and fast, but the signal quality calculations become inaccurate leading to inappropriate data rate selection
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values for frequency errors in a lookup table before actual noise estimation processing. The receiver measures frequency error, uses it to index the lookup table, and retrieves pre-computed compensation values. This avoids complex real-time calculations during noise estimation while still achieving accurate frequency error compensation, thus improving measurement precision without significantly increasing processing complexity.
2Reliability
If accurate noise estimation is performed without frequency error compensation, then processing remains computationally efficient, but data transmission reliability decreases due to erroneous signal quality reports
Solution Approach 1:
The patent implements self-service by having the receiver autonomously measure its own frequency error using pilot symbols and automatically retrieve appropriate compensation values from the lookup table. The system serves itself by using its own measured parameters (frequency error) to select compensation values, without requiring external assistance or complex coordinated processing. This improves transmission reliability through accurate noise estimation while keeping processing power requirements moderate.
3Measurement precision
If frequency error compensation is implemented in real-time noise estimation, then signal quality measurements improve, but processing time and computational load increase
Solution Approach 1:
The patent uses preliminary action by pre-computing frequency error compensation values and storing them in a lookup table during system initialization or setup. During real-time operation, the receiver only needs to measure the frequency error, use it as an index to retrieve pre-computed values from the lookup table, and apply them to noise estimation. This eliminates complex real-time calculations, significantly reducing processing time while maintaining high CQI measurement accuracy.
Data Source
AI summary
A receiver circuit provides improved noise estimation processing by at least partially removing receiver frequency error bias. An initial noise estimate is compensated using an error term based on the observed receiver frequency error, and the resulting compensated noise estimate can be used to improve other signal processing in the receiver. For example, the receiver may use compensated noise estimates to generate signal quality estimates, e.g., Signal-to-Interference (SIR) estimates, having improved accuracy. Additionally, or alternatively, the receiver may use the compensated noise estimates to generate RAKE combining weights having improved noise suppression characteristics. In an exemplary embodiment, the initial noise estimate is a noise correlation matrix generated from a received reference signal, e.g., pilot symbols, and the error term is an error matrix directly generated using he observed receiver frequency error and channel estimates taken from the reference signal.