noise.m

stbc for flat rayleigh fading channel

function n=noise(snr,Nr,Nt,mod_scheme,temp_data_trans)

%             n=awgn(temp_data_trans,snr,0);
            % here n=No/2;snr is in db. and '0' = signalpower in dbw. since
            % it is normalized it is 0 dbw.
       if(strcmp(mod_scheme,'psk')||strcmp(mod_scheme,'Psk')||strcmp(mod_scheme,'PSK'))
           sig=1/(2*(10^(snr/10)));
           if(isreal(temp_data_trans))
               n= sig * randn(Nr,Nt);
           else
               n = sig * (randn(Nr,Nt) + j*randn(Nr,Nt));
           end
       else
%            Es=abs(temp_data_trans);
%            si=sqrt(0.5*Es/10^(snr/10));
%            sig=[];
%            for i=1:Nr
%                sig=[sig;si'];
%            end
           sig=sqrt(1/10^(snr/10));
           n = sig .* (randn(Nr,Nt) + j*randn(Nr,Nt));
       end