OFDM CINR Estimation with Error Floor Removal
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Solution Overview
Problem
In OFDM communication systems, inaccurate sliding average window (SAW) channel estimation values lead to an error floor phenomenon, resulting in overestimation of the carrier to interference and noise ratio (CINR) and deteriorating the performance of adaptive power control and modulation/coding devices.
Innovation Solution
An apparatus and method that utilize accurate SAW channel estimation values by performing inverse calculations based on real channel pass signal values to remove the error floor from CINR estimation values, ensuring precise CINR estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If SAW channel estimation method is used to calculate CINR, then the calculation process is simple, but the CINR estimation value is inaccurate due to error floor phenomenon
Solution Approach 1:
The patent segments the CINR estimation process into two distinct parts: first calculating the CINR estimation value using the simple SAW method, then separately calculating the error floor value and subtracting it from the estimation value. This segmentation allows the system to maintain calculation simplicity while improving accuracy by addressing the error source independently.
Solution Approach 2:
The patent introduces an intermediary calculation step that computes the error floor value based on noise power and channel estimation characteristics. This intermediary value acts as a correction factor that bridges the gap between the simple SAW estimation and the accurate true CINR value, enabling high accuracy without complicating the overall process.
2Speed
If inaccurate CINR estimation value is used, then the calculation process is fast, but the performance of adaptive power control and modulation/coding devices deteriorates
Solution Approach 1:
The patent performs preliminary calculation of the error floor value using pre-established relationships between noise power, channel estimation values, and error characteristics. By preparing this correction value in advance through a straightforward calculation based on readily available parameters, the system maintains fast processing speed while ensuring reliable CINR estimation for adaptive control decisions.
3Measurement precision
If error floor value is removed from CINR estimation, then the CINR estimation accuracy is improved, but the calculation complexity increases
Solution Approach 1:
The patent changes the approach from directly estimating CINR using complex methods to using parameter transformation: it expresses the error floor value in terms of fundamental parameters (noise power, channel estimation magnitude) that are already available in the system. This parameter transformation enables accurate CINR estimation while keeping the calculation complexity low, as it reuse existing parameters rather than introducing new complex measurements.
Data Source
AI summary
An apparatus and a method for estimating a carrier to interference and noise ratio (CINR) in a communication system. The CINR value is precisely estimated by removing the error floor value, which is caused by the inaccurate sliding average window SAW channel estimation value, from the CINR estimation value. Since the CINR value is precisely estimated, performance of the adaptive power control or the adaptive modulation and coding device is improved.