Generate noise using Box muller meathod

Question

Ronak Sakaria 2012-6-8

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/40687-generate-noise-using-box-muller-meathod

评论： Ali Sabra 2019-10-24

采纳的回答： the cyclist

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What are the other meathod for generating Guassian Noise?

I wrote code for Box muller like:

noise = rand(2,length(data));

AWGN_noise = zeros(1,length(data));

for i1=1:length(data)

AWGN_noise(i1) = sigma_noise * sqrt(-2*log(noise(1,i1)))*cos(2*pi*noise(2,i1));
end

The thing is that I'm not getting much variance in values after Box Muller Transformation. Suggest me some good code to generate guassian noise.

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Answer 1

the cyclist 2012-6-8

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https://ww2.mathworks.cn/matlabcentral/answers/40687-generate-noise-using-box-muller-meathod#answer_50336

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If I set sigma_noise to 1, then the variance of your noise is also 1, exactly as I would expect. (See for example http://en.wikipedia.org/wiki/Box%E2%80%93Muller_transform.) If you increase the value of sigma_noise, then you'll get more variance.

Also, your code can be vectorized to have a significant speedup. Replace your for loop with:

AWGN_noise = sigma_noise * sqrt(-2*log(noise(1,:))).*cos(2*pi*noise(2,:));

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Ronak Sakaria 2012-6-8

Are you aware of Sigma for QPSK modulation? My theory and simulation BER result doesnt match very much. I know that it depends on sigma of noise but i have tried various values of sigma and i am not getting good simultation BER curve, And thanks for suggesting alternate for for loop. I'm making less error than theoritical case at higher SNR.

Ali Sabra 2019-10-24