Receiver Interference Estimation Under Residual Frequency Error
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Solution Overview
Problem
Current SIR estimation algorithms in WCDMA systems are affected by residual frequency errors, leading to erroneous power control and increased downlink power levels when interference is low, due to their dependence on interference levels that are heavily influenced by frequency errors.
Innovation Solution
A method and apparatus for estimating interference levels in a receiver, which detects low interference and adjusts the estimation process by either estimating in only the radial direction or de-rotating the received signal to compensate for residual frequency errors, using specific equations and AFC device estimates to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SIR estimation algorithms are used, then the system can operate with standard power control, but the presence of residual frequency errors causes erroneous interference level detection and increased downlink power levels
Solution Approach 1:
The patent applies dynamics by making the interference estimation process adaptive based on detected frequency error conditions. When frequency errors are detected, the system dynamically switches to a corrected estimation method that compensates for the errors, whereas under normal conditions it uses standard estimation. This dynamic adaptation resolves the contradiction by ensuring measurement precision is maintained across varying operational conditions.
Solution Approach 2:
The patent changes the estimation parameters and mathematical operations based on frequency error detection. Specifically, it modifies the interference estimation algorithm to account for frequency offsets, transforming the standard estimation parameters into corrected ones that remain accurate despite frequency errors. This parameter transformation resolves the contradiction between measurement precision and reliability.
2Device complexity
If standard interference estimation is performed, then the processing is simple, but residual frequency errors lead to erroneous estimates and increased power consumption
Solution Approach 1:
The system dynamically adjusts the complexity of the estimation process based on frequency error conditions. When frequency errors are detected, it switches to a more complex corrected estimation method; otherwise, it uses the simpler standard method. This dynamic approach resolves the contradiction by only increasing complexity when necessary to reduce power consumption.
Solution Approach 2:
The patent employs a lightweight frequency error detection mechanism that quickly identifies when corrected estimation is needed. This simple detection layer acts as a gatekeeper, allowing the system to use the computationally inexpensive standard estimation most of the time while only invoking the more complex corrected method when absolutely necessary, thus resolving the contradiction between simplicity and energy efficiency.
3Measurement precision
If frequency error compensation is always applied, then estimation accuracy is maintained, but the processing complexity and computational load increase
Solution Approach 1:
The patent implements a dynamic selection mechanism that chooses between standard and corrected estimation methods based on real-time frequency error detection. This resolves the contradiction by applying frequency error compensation only when needed, maintaining accuracy while avoiding unnecessary processing complexity during normal operation.
Solution Approach 2:
The system applies different estimation qualities to different operational contexts. When frequency errors are present, it uses the higher-quality corrected estimation; when absent, it uses the lower-quality but simpler standard estimation. This local differentiation of quality resolves the contradiction between maintaining precision and managing complexity.
Data Source
AI summary
Methods and apparatus for estimating interference level in a receiver are dominated by the receiver's residual frequency error when the interference is low. The interference estimation method can be changed when the interference is low such that it compensates for the effects of residual frequency errors. A method of estimating an interference level includes the steps of detecting an interference level of the received signal; determining whether the detected interference level is low; and if the detected interference level is low, estimating the interference level by at least one of estimating in only a radial direction and de-rotating the received signal before estimating the interference level.