How to create AWGN channel in MATLAB?

I need to create an AWGN, Rayleigh and Rician channel in MATLAB to reduce the transmission power in real time. So that I have to generate a 2*2 and 4*4 channel matrix. For Rayleigh and Rician I created the matrix as shown below. Now please help me to find the channel matrix for AWGN channel. I don't have any idea to construct the matrix for AWGN channel.

Rayleigh fading channel

 H1=sqrt(0.5)(randn+1irandn)(1/sqrt(2))

Rician channel

t=0.01 for k=1:1:4 H1=(kcos(t)+randn(2,2)/sqrt(2))+j+[k*sin(t)+randn(2,2)/sqrt(2)] End

Similarly i have to create AWGN channel matrix in matlab so help me to create the AWGN channel matrix Thankz in Advance.

[Sivakumaran Chandrasekaran]

inbuilt awgn command is present in matlab. you can use it

Answer 1

[Walter Roberson]

You have not used valid code.

   H1 = sqrt(0.5)*(randn+1i*randn)*(1/sqrt(2));

and

t = 0.01;
for k = 1:4
  H1(:,:,k) = (k*cos(t)+randn(2,2)./sqrt(2)) + j + (k*sin(t)+randn(2,2)./sqrt(2));
end

It looks likely to me that you did not mean "j+" and instead mean "j*" with j meaning sqrt(-1), the same as 1i . If so then

t = 0.01;
for k = 1:4
  H1(:,:,k) = (k*cos(t)+randn(2,2)./sqrt(2)) + 1i * (k*sin(t)+randn(2,2)./sqrt(2));
end

This would result in a 2 x 2 x 4 matrix