% Active Passive RIS Comparison
% 08.04.2021
% by Ertugrul Basar - CoreLab
% Present and Future of Reconfigurable Intelligent Surface-Empowered Communications


clear all;clc

% System Parameters
PTdBm=20;      %transmit power
PT=10^([(PTdBm-30)]/10);  
PAdBm=20;      %max reflect power
PA=10^([(PAdBm-30)]/10);  
Sigma2dBm=-90; % noise power
Sigma2=10^([(Sigma2dBm-30)]/10); 
Sigmav2dBm=-90; % RIS noise power
Sigmav2=10^([(Sigmav2dBm-30)]/10); 

freq=5*10^9;     % frequency
lambda=(3*10^8)/freq;   % wavelength

N=256;          % RIS size
B=N*lambda/2 ;  %far-field boundry




% Coordinates
AP=[0,0];
RIS=[10,20];

% Test Point (12)
Test=[15,15
      20,15
      25,15
      30,15
      17.5,10
      22.5,10
      27.5,10
      32.5,10
      20,5
      25,5
      30,5
      35,5];
  
dSR=norm(AP-RIS);  

dRD=zeros(1,12);
for ii=1:12
dRD(ii)=norm(RIS-Test(ii,:));
end

Gamma_Passive=zeros(1,12);
Gamma_Active=zeros(1,12);
Gamma_Specular=zeros(1,12);
for ii=1:12

Gamma_Passive(ii)= 10*log10((N^2 * lambda^4 * PT)/ ( 256*pi^4* dSR^2 * dRD(ii)^2 *Sigma2)) ;
Gamma_Active(ii) = 10*log10( (N*PT*PA) / ( 16*pi^2*PA*Sigmav2*dSR^2 / lambda^2   +   16*pi^2*Sigma2*dRD(ii)^2 / lambda^2  +  (Sigma2*Sigmav2*256* pi^4 * dSR^2 * dRD(ii)^2  /(N*lambda^4)) ) );
Gamma_Specular(ii)=10*log10( PT*lambda^2 /(Sigma2*16*pi^2*(dSR+dRD(ii))^2  ) );

end

% Amplification factor (check)
p=10*log10(sqrt(PA/(N*lambda^2 /(16*pi^2*dSR^2) + Sigmav2)));

% Specular reflection comparison
Ratio= 10*log10 (N*PA*(dSR+dRD).^2 ./ (PA*dSR^2+dRD.^2) );