channelsui.m

802.16 physical layer simulation through diferent SUI Channel.

function channel = channelSUI(N_SUI,G,BW)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%                                                                        %
%%     Name: channelSUI.m                                                 %
%%                                                                        %
%%     Description: It generates the Channel Impulse Response of the      %
%%     channel variant by using Jakes Model.                              %
%%                                                                        %
%%     The Channel used depends on the parameters that are indicated      %
%%     to it. We can simulate SUI channeles 1 to 6, with different        %
%%     bandwidths.                                                        %
%%                                                                        %
%%     Parameters:                                                        %
%%      N_SUI = Channel to simulate.    G = Size of the cyclic prefix     %
%%      v = Speed of the system.        BW = Bandwidth of the channel     %
%%                                                                        %
%%                                                                        %
%%     Authors: Bertrand Muquet, Sebastien Simoens, Shengli Zhou          %
%%      October 2000                                                      %
%%     Modification : Carlos Batlles - April 2007                         %
%%                                                                        %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Speed of the receiver 0.001 m/s
v = 0.001;                      

% We are going to consider that we are sending a unique symbol
FrameLength = 1;                 

% The following parameters are with which we calculated the duration of the symbol in WiMAX
Nfft = 256;
BW = BW*1e6;

% Factor of correction
if mod(BW,1.75)==0
    n = 8/7;
elseif mod(BW,1.5)==0
    n = 86/75;
elseif mod(BW,1.25)==0
    n = 144/125;
elseif mod(BW,2.75)==0
    n = 316/275;
elseif mod(BW,2)==0
    n = 57/50;
else 
    n = 8/7;
end

if N_SUI~=0
    Fs = floor(n*BW/8000)*8000;         % Sampling frequency
    deltaF = Fs / Nfft;                 % Subcarrier spacing.
    Tb = 1/deltaF;                      % Useful symbol time (data only)
    Ts = Tb * (1+G);                    % OFDM symbol time (data + cyclic prefix)
    T = 1/(Fs*1e-6);                    % Duration in microseconds of each carrier



      
      %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
      %                                                           %
      %  The parameters given back are the following:             %
      %                                                           %
      %    P --> Power of each path (dB)                          %
      %    K --> Factor K of the Ricean distribution (Linear)     %
      %    tau --> Delay of each path (microseconds)              %
      %    Dop --> Maximum Doppler frequency (Hertz)              %
      %    ant_corr --> Coefficient of antenna correlation        %
      %    Fnorm --> Normalizing factor of gain (dB)              %
      %                                                           %
      %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

switch N_SUI
    case 1
        powers = [ 0 -15 -20 ];
        K = [ 4 0 0 ];
        delays = [ 0.0 0.4 0.9 ];
        Dop = [ 0.4 0.3 0.5 ];
        ant_corr = 0.7;
        Fnorm = -0.1771;
    case 2
        powers = [ 0 -12 -15 ];
        K = [ 2 0 0 ];
        delays = [ 0.0 0.4 1.1 ];
        Dop = [ 0.2 0.15 0.25 ];
        ant_corr = 0.5;
        Fnorm = -0.3930;
    case 3
        powers = [ 0 -5 -10 ];
        K = [ 1 0 0 ];
        delays = [ 0.0 0.4 0.9 ];
        Dop = [ 0.4 0.3 0.5 ];
        ant_corr = 0.4;
        Fnorm = -1.5113;
    case 4
        powers = [ 0 -4 -8 ];
        K = [ 0 0 0 ];
        delays = [ 0.0 1.5 4.0 ];
        Dop = [ 0.2 0.15 0.25 ];
        ant_corr = 0.3;
        Fnorm = -1.9218;
    case 5
        powers = [ 0 -5 -10 ];
        K = [ 0 0 0 ];
        delays = [ 0.0 4.0 10.0 ];
        Dop = [ 2.0 1.5 2.5 ];
        ant_corr = 0.3;
        Fnorm = -1.5113;
    case 6
        powers = [ 0 -10 -14 ];
        K = [ 0 0 0 ];
        delays = [ 0.0 14.0 20.0 ];
        Dop = [ 0.4 0.3 0.5 ];
        ant_corr = 0.3;
        Fnorm = -0.5683;
end
  Dop = max (Dop);
  
  %% The delays are normalized
  sz=size(delays);
  if (and(sz(1) ~= 1,sz(2) == 1)) delays=delays.';
  elseif (and(sz(1) ~= 1,sz(2) ~= 1)) 'Error: The delay must be a vector';
  end
  
  % Now the delays express themselves in number of samples.
  delays=delays/T; 
  
  nbtaps=length(powers);
  len_cir=1+round(max(delays));
  variances=zeros(1,len_cir);
  
  %% Calculate the amplitude of each path.
  sz=size(powers);
  if (and(sz(1) ~= 1,sz(2) == 1)) powers=powers.';
  elseif (and(sz(1) ~= 1,sz(2) ~= 1)) 'Error: The powers must be a vector';
  end

  %% The powers are in dB -> With this order the variance is calculated to recombine the power of every path
  
  variances2=10.^(powers/10);
  
  %% Normalize the powers
  variances2=variances2/sum(variances2);

  %% Finally, the discreet CIR is calculated bringing every path to the following sample
  for i=1:nbtaps
    variances(1+round(delays(i)))=variances(1+round(delays(i)))+ variances2(i);
  end

  Lc=length(variances)-1;
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    

hfr=[];
  fc = 2.3e9; 			% Carrier Frequency in Hertz (2.5GHz 3.2GHz)
  fdmax = Dop;        
  
  N = 100;                      % Number of incident waves
  t = Ts:Ts:Ts*FrameLength;               % The variable "time"

  len = length(t);
  theta = rand(1,N)*2*pi;              % Generating the uniform phases
  fd = cos(2*pi*((1:N)/N))*fdmax;      % Generate eqaul-spaced frequencies from  "-fdmax" to "+fdmax"
  
 
  E = exp(j.*(2*pi*fd(:)*t(:)'+repmat(theta(:),1,len)));
  E = E/sqrt(N);
  fadingcoeff = sum(E);
  %plot(t,abs(fadingcoeff))
  %xlabel('time (second)');ylabel('Envelope of the fading coefficient');
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    for ih=1:Lc+1
      hfr=[hfr;fadingcoeff];     
    end
    hfr=diag(variances.^0.5)*hfr;
    %% hfr has a size of (Lc+1)x(FrameLength)
    %% hfr(:,i) It contains the CIR(Channel Impulse Response) corresponding to the transmission of symbol i

    % Finally, the values of the channel are normalized.
    channel = hfr ./ norm(hfr);
    
elseif N_SUI == 0
    channel = 1;         % If an AWGN channel is chosen, the channel will be the unit.
end