How to Estimate noise variance without prior knowledge about the signal-to-noise ratio (SNR)

[thanhttttt]

I found that the PUSCHReceiver uses noise variance (no) as input for the CE and EQ blocks, but in practice, the receiver does not know the value of the noise variance. How should this be handled in such a scenario?

[SebastianCa]

Hi @thanhttttt,
In such a scenario, a noise variance estimator is required. One straightforward approach is to estimate no using empty resource elements, such as unused DMRS positions.

[thanhttttt]

Hi, @SebastianCa,
Thank you for your response. However, I still have a question. When the PUSCH grid is small (e.g., 4 RBs), there may not be enough positions for accurate variance estimation. Is there a more efficient solution?

[SebastianCa]

Hi @thanhttttt,
a practical solution is to look at unused PRBs to estimate no (the entire resource grid is usually larger than 4 PRBs).

[thanhttttt]

That’s a great idea! Thank you, @SebastianCa