Ergodic_Capacity_vs_SNR.m

% Ergodic_Capacity_vs_SNR.m
% To plot Fig. 4.5 on p73 of the book
% "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; 
for Icase=1:5
   if Icase==1,  nT=4; nR=4;      % 4x4
    elseif Icase==2, nT=2;  nR=2; % 2x2
    elseif Icase==3, nT=1;  nR=1; % 1x1
    elseif Icase==4, nT=1;  nR=2; % 1x2
    else   nT=2;  nR=1;          % 2x1
   end
   n=min(nT,nR);  I = eye(n);
   C(Icase,:) = zeros(1,length(SNR_dB));
   for iter=1:N_iter
      H = sqrt(0.5)*(randn(nR,nT)+j*randn(nR,nT));  
      if nR>=nT,  HH = H'*H;  else  HH = H*H';  end
      for i=1:length(SNR_dB) %random channel generation
         C(Icase,i) = C(Icase,i)+log2(real(det(I+SNR_linear(i)/nT*HH)));
      end
   end
end
C = C/N_iter;
figure, plot(SNR_dB,C(1,:),'b-o', SNR_dB,C(2,:),'b-<', SNR_dB,C(3,:),'b-s');
hold on, plot(SNR_dB,C(4,:),'b->', SNR_dB,C(5,:),'b-^');
xlabel('SNR[dB]'); ylabel('bps/Hz'); set(gca,'fontsize',10); grid on
s1='{\it N_T}=1,{\it N_R}=1'; s2='{\it N_T}=1,{\it N_R}=2'; 
s3='{\it N_T}=2,{\it N_R}=1'; s4='{\it N_T}=2,{\it N_R}=2'; s5='{\it N_T}=4,{\it N_R}=4';
legend(s1,s2,s3,s4,s5)