OFDM Noise Variance Estimation Using Channel Estimate Differences
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing noise variance estimation techniques in OFDM receivers are inaccurate, particularly in conditions where noise variance cannot be reliably estimated without pilots or reference signals, affecting the performance of digital radio systems like DAB.
Innovation Solution
A method for estimating noise variance in OFDM receivers that involves determining channel estimates for frequency carriers within an evaluation window, calculating differences between carriers, and using these differences to estimate noise variance, which can be further filtered using an infinite impulse response filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional noise variance estimation techniques are used in OFDM receivers, then the system can operate without pilots or reference signals, but the accuracy of noise variance estimation deteriorates
Solution Approach 1:
The patent introduces channel estimates as an intermediary to enable noise variance estimation. By determining channel estimates for multiple frequency carriers and using these estimates as a mediator to calculate noise variance through differences between carriers, the system achieves accurate noise variance estimation without requiring pilots or reference signals. The channel estimates serve as the intermediary that bridges the gap between received signals and noise variance calculation.
2Measurement precision
If noise variance is estimated using differences between channel estimates of multiple carriers, then estimation accuracy improves, but device complexity increases
Solution Approach 1:
The patent segments the noise variance estimation process into distinct steps: determining channel estimates for multiple frequency carriers within an evaluation window, selecting one carrier, calculating differences between the selected carrier and other carriers, and computing noise variance from these differences. This segmentation allows the complex estimation to be broken down into manageable operations that can be efficiently implemented in the receiver.
Solution Approach 2:
The patent applies local quality by focusing the analysis on a specific evaluation window containing a subset of frequency carriers rather than processing the entire spectrum. By concentrating the channel estimate determination and difference calculation on this localized subset, the system achieves accurate noise variance estimation while reducing the overall processing complexity and computational burden.
Data Source
AI summary
Systems and methods for estimating noise variance are provided. In one aspect, an apparatus includes a front end circuit configured to receive a radio frequency signal and process the radio frequency signal into a plurality of samples and a transform engine configured to convert at least one of the samples into a plurality of frequency carriers. The apparatus further includes a detector configured to determine a channel estimate for a subset of the frequency carriers located within an evaluation window, select one of the carriers within the evaluation window, determine differences between the channel estimate of the selected carrier and the channel estimates of other carriers within the evaluation window, and estimate the noise variance for a symbol including the at least one of the samples based on the differences between the channel estimate of the selected carrier and the channel estimates of other frequency carriers within the evaluation window.