gkamendje
Newbie level 3
modelling AWGN question
In my simulations up to now using BPSK signaling, the AWGN channel was modelled by simply adding a gaussian real value to the transmitted symbol. However, I came across some matlab AWGN modelling like this one which add a complex value to the transmitted symbol
function Y =awgn(X, sigma)
% AWGN GENERATOR
% 07-31-1993
% Awgn is an m-file that adds awgn noise to the matrix X
% Where sigma is standard deviation of the noise
% Ec/No- 1/(2*sigma^2).
[rr,ccJ =size(X);
W =randn(rr,cc)+ i*randn(rr,cc);
Y=X+sigma.*W;
disp('AWGN IS ADDED TO SIGNAL');
(From Mehmet Kutlu: Kalman Filtering Approach to blind equalization).
My question is the following: Why is it necessary to add a complex noise value while we are dealing with BPSK symbols which are +1 or -1? Is it because of the subsequent filtering? How does this translate into physical (real electrical) quantities? Any link to a book or an article that explains this in details will be appreciated.
Thanks GA
In my simulations up to now using BPSK signaling, the AWGN channel was modelled by simply adding a gaussian real value to the transmitted symbol. However, I came across some matlab AWGN modelling like this one which add a complex value to the transmitted symbol
function Y =awgn(X, sigma)
% AWGN GENERATOR
% 07-31-1993
% Awgn is an m-file that adds awgn noise to the matrix X
% Where sigma is standard deviation of the noise
% Ec/No- 1/(2*sigma^2).
[rr,ccJ =size(X);
W =randn(rr,cc)+ i*randn(rr,cc);
Y=X+sigma.*W;
disp('AWGN IS ADDED TO SIGNAL');
(From Mehmet Kutlu: Kalman Filtering Approach to blind equalization).
My question is the following: Why is it necessary to add a complex noise value while we are dealing with BPSK symbols which are +1 or -1? Is it because of the subsequent filtering? How does this translate into physical (real electrical) quantities? Any link to a book or an article that explains this in details will be appreciated.
Thanks GA
