how to add white gaussian noise in controller design?

hello,

i have a matlab script of LQG controller design and i want to add white gaussian noise in controller design how should i add it in script ?

in the following code there are two noise covariances, process and measured.

I want to add white Gaussian noise in the place of measured noise covariance

how should i do this ?

*******************************

clear all; clc; close all

load sec_sumsin_ABCDmatrix.mat % data As,Bs,Cs,Ds discrete measured data

syss=ss(As,Bs,Cs,Ds,0.001);

figure(1)

pzmap(syss)

syssc=d2c(syss,'tustin'); % convert from discrete to continuous

figure(4)

pzmap(syssc)

[Asc,Bsc,Csc,Dsc]=ssdata(syssc);

%%%%%define noise covariance and weighting matrices%%%%%%%%

nx=10; % states

ny=1; % output

nu=1; % input

M=diag([1.8108e0*ones(1,ny)]);

QX=Csc'*M*Csc;

f=zeros(nx,1);

g=zeros(1,nx);

QU=diag([3.9805e-8*ones(1,nu)]);

QXU=[QX f;g QU]; % design QXU weighting matrices

QW=1e-3*eye(nx); % process noise covariance

QV=1e-10*eye(ny); % measurement noise covariance

QWV=[QW f;g QV]; % design QWV weighting matrices

%%%%LQG Regulator%%%%%%

KlQG=lqg(syssc,QXU,QWV) % desing LQG regulator

%%%%%%%%%%%%%%%%%%%%%%%

[aa,bb,cc,dd]=ssdata(KlQG)

sysc=feedback(syssc,KlQG); % closed loop system

figure(2)

bode(syssc,'r')

hold on

bode(sysc,'b')

figure(3)

bode(KlQG,'g')

******************************

the representation of above code is like this, in the figure i have added white gaussian noise, instead of measurement noise .

and i want to write in the script for this .