OL_CL_Comparison.m

%OL_CL_Comparison.m
% To plot Fig. 4.6 on p74 of
% "Introduction to Space-Time Wireless Communications", A. Paulraj, R. Nabar and D. Gore

%MIMO-OFDM Wireless Communications with MATLAB¢ç   Yong Soo Cho, Jaekwon Kim, Won Young Yang and Chung G. Kang
%2010 John Wiley & Sons (Asia) Pte Ltd

clear all, close all;
SNR_dB=[0:5:20];  SNR_linear=10.^(SNR_dB/10.);
N_iter=1000; 
%%----------------- 4x4 -----------------------------
nT=4;  nR=4;  n=min(nT,nR);  I = eye(n); 
rho=0.2;   sq2=sqrt(0.5);
Rtx=[1      rho     rho^2   rho^3;  rho     1      rho    rho^2;
    rho^2   rho     1       rho;   rho^3   rho^2   rho     1];
rho=0.2;
Rrx=[1      rho     rho^2   rho^3;  rho     1       rho     rho^2;
    rho^2   rho     1       rho;   rho^3   rho^2   rho     1];
C_44_OL=zeros(1,length(SNR_dB)); C_44_CL=zeros(1,length(SNR_dB));
for iter=1:N_iter
   Hw = sq2*(randn(4,4) + j*randn(4,4));
   H = Rrx^(1/2)*Hw*Rtx^(1/2);  tmp = H'*H/nT;  SV = svd(H'*H);
   for i=1:length(SNR_dB)
      %random channel generation
      C_44_OL(i) = C_44_OL(i) + log2(det(I+SNR_linear(i)*tmp));
      Gamma = Water_Pouring(SV,SNR_linear(i),nT);
      C_44_CL(i) = C_44_CL(i)+log2(det(I+SNR_linear(i)/nT*diag(Gamma)*diag(SV)));
   end
end
C_44_OL = real(C_44_OL)/N_iter;  C_44_CL = real(C_44_CL)/N_iter;
figure, plot(SNR_dB, C_44_OL,'-o', SNR_dB, C_44_CL,'-<');
xlabel('SNR [dB]'); ylabel('bps/Hz');  set(gca,'fontsize',10);
legend('Channel Unknown','Channel Known'); grid on