[SOLVED] how to calculate noise variance from noise power spectral density value

[rit]

can anyone tell me how to calculate noise variance σ²/2, if the noise power spectral density is set to -162dBm/Hz. Noise component is additive white circularly symmetric gaussian complex noise. How noise variance is related to noise power spectral density?

Thanks.

 

[bulx]

since PSD is flat here, total noise power across all frequencies = BW * PSD
This is the same as the variance of the noise = σ²/2
Agree?
- b

 

[rit]

since PSD is flat here, total noise power across all frequencies = BW * PSD
This is the same as the variance of the noise = σ²/2
Agree?
- b

means -162dBm = σ²/2
and what is bw? is it 1Hz.
is this right?
thanks

 

[bulx]

eqn holds, if you convert left side to simple ratio from dBm. you'll have to find out whats the relevant BW, it is not mentioned in the first post. You could also assume the BW of the noise is the same as that for your signal, but it really depends on the system.
- b

 

[rit]

this problem is for wireless cellular system. bw is not mentioned in problem. signal may be narrowband signal.

 

[rit]

eqn holds, if you convert left side to simple ratio from dBm. you'll have to find out whats the relevant BW, it is not mentioned in the first post. You could also assume the BW of the noise is the same as that for your signal, but it really depends on the system.
- b

This problem is for wireless cellular system. bw is not mentioned in problem. signal may be narrowband signal.

 

[Ahmed Alaa]

linear (-162dBm) = σ²/2, the variance corresponds to amplitude of PSD not the total power, you don't have to know the BW, right ?