Noise Power and SNR Estimation via Residual CFO Compensation
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Solution Overview
Problem
In wideband wireless communication systems, estimating noise power and signal-to-noise ratio (SNR) accurately is challenging due to carrier frequency offsets (CFO) and sampling clock offsets (SCO), which cause inter-carrier interference (ICI) and affect communication performance.
Innovation Solution
A method and device for estimating noise power and SNR by compensating for phase differences between training symbols using residual CFOs calculated from a reference CFO, thereby minimizing ICI and improving estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If carrier frequency offset compensation is performed using a single reference CFO, then the device complexity is reduced, but the measurement precision of noise power and SNR estimation deteriorates due to residual phase differences across subcarriers
Solution Approach 1:
The patent divides the CFO compensation process into two segments: first applying a reference CFO correction to all subcarriers, then calculating and applying residual CFO corrections specifically for each subcarrier. This segmentation allows the system to maintain low overall complexity while achieving high precision by focusing detailed correction only where necessary.
Solution Approach 2:
The patent applies different levels of CFO compensation to different parts of the signal: a coarse reference CFO correction is applied globally, while fine residual CFO corrections are applied locally to each subcarrier. This local quality approach ensures high estimation accuracy for noise power and SNR without requiring full precision correction across the entire signal processing chain.
2Measurement precision
If residual CFOs are calculated for each subcarrier, then the measurement precision of noise power and SNR estimation is improved, but the loss of time increases due to additional calculation steps
Solution Approach 1:
The patent performs preliminary CFO estimation and reference correction before the main noise power and SNR estimation process. By pre-calculating the reference CFO and applying it to all training symbols, the system reduces the amount of computation needed during the actual estimation phase, thereby improving precision without proportionally increasing total processing time.
Solution Approach 2:
The patent calculates residual CFOs for each subcarrier only when needed for high-precision estimation, rather than always performing full residual correction. This partial action approach allows the system to achieve high measurement precision when required while avoiding unnecessary computation in scenarios where lower precision would suffice, thus balancing accuracy with processing time.
Data Source
AI summary
A method of a wireless communication device, includes compensating for a first phase of a first training symbol and a second phase of a second training symbol following the first training symbol, based on a reference carrier frequency offset (CFO) corresponding to one of a plurality of subcarriers of a received frame in a time domain; calculating residual CFOs respectively for the plurality of subcarriers of the received frame, based on the reference CFO; compensating for phase differences between the first training symbol and the second training symbol for each of the plurality of subcarriers, based on the residual CFOs in a frequency domain; and estimating at least one of noise power and signal-to-noise ratio (SNR) of the received frame, based on the first training symbol and the second training symbol after compensating for the phase differences between the first training symbol and the second training symbol.