rx_convert_to_freq.m

外文经典书“Space-time codes and MIMO systems”第九章matlab源代码

function [freq_tr_syms, freq_data_syms] = rx_convert_to_freq(time_signal, SimulationParameters)

global SimulationConstants;
[n_tx_antennas, n_rx_antennas] = get_n_antennas(SimulationParameters);

fft_length=SimulationParameters.FFTPoints;
for rx_ant = 1:n_rx_antennas
    % Long Training symbols
   if SimulationParameters.TxDiv==0 
      long_tr_syms = time_signal(rx_ant,1:2*fft_length);
      long_tr_syms = reshape(long_tr_syms, fft_length, 2);
  elseif SimulationParameters.TxDiv==2
      long_tr_syms = [time_signal(rx_ant,1:fft_length) time_signal(rx_ant,(fft_length+17):(2*fft_length+16))];
      long_tr_syms = reshape(long_tr_syms, fft_length, 2);
  elseif SimulationParameters.TxDiv==4
      long_tr_syms = [time_signal(rx_ant,1:fft_length) time_signal(rx_ant,(fft_length+17):(2*fft_length+16)) time_signal(rx_ant,(2*fft_length+33):(2*fft_length+96)) time_signal(rx_ant,(2*fft_length+113):(4*fft_length+48))];
      long_tr_syms = reshape(long_tr_syms, fft_length, 4);
  end
  
    %check if there is zero padding
  if SimulationParameters.ZeroPad~=1
      numdatasubc=1;
  else
    numdatasubc=SimulationConstants.NumDataSubc;
  end

   % to frequency domain
   freq_long_tr = fft(long_tr_syms)/(fft_length/sqrt(numdatasubc))/sqrt(n_tx_antennas);
   reorder = [(fft_length/2)+1:fft_length 1:fft_length/2];
   freq_long_tr(reorder,:) = freq_long_tr;
   
   % Select training carriers
   freq_tr_syms = freq_long_tr;
   
   %if there is a zeropad option
   if SimulationParameters.ZeroPad==1
      num_data_carriers=SimulationConstants.NumDataSubc;
      x=fft_length-num_data_carriers;
      freq_tr_syms=freq_tr_syms([x/2:x/2+num_data_carriers/2-1 ((x/2+num_data_carriers/2)+1):fft_length-(fft_length-num_data_carriers)/2],:);
   end

   
   
   % Take data symbols
   if ~SimulationParameters.TxDiv
      data_syms = time_signal(rx_ant,(2*fft_length)+1:length(time_signal));
  elseif SimulationParameters.TxDiv==2
      data_syms = time_signal(rx_ant, (2*fft_length+16)+1:length(time_signal));
  elseif SimulationParameters.TxDiv==4
      data_syms = time_signal(rx_ant, (4*fft_length+49):length(time_signal));
   end
   data_sig_len = length(data_syms);
   n_data_syms = floor(data_sig_len/(fft_length+16));

   % Cut to multiple of symbol period
   data_syms = data_syms(1:n_data_syms*(fft_length+16));
   data_syms = reshape(data_syms, (fft_length+16), n_data_syms);
   % remove guard intervals
   data_syms(1:16,:) = [];

   %check if there is zero padding
    if SimulationParameters.ZeroPad~=1
        numdatasubc=1;
    else
        numdatasubc=SimulationConstants.NumDataSubc;
    end

   % perform fft
   freq_data = fft(data_syms)/(fft_length/sqrt(numdatasubc))/sqrt(n_tx_antennas);
   
   %Reorder pattern is [33:64 1:32]
   freq_data(reorder,:) = freq_data;
   
   %if there is a zeropad option
   if SimulationParameters.ZeroPad==1
       num_data_carriers=SimulationConstants.NumDataSubc;
       x=fft_length-num_data_carriers;
       freq_data=freq_data([x/2:x/2+num_data_carriers/2-1 ((x/2+num_data_carriers/2)+1):fft_length-(fft_length-num_data_carriers)/2],:);
   end

   tmp_freq_tr(rx_ant,:,:) = freq_tr_syms;
   tmp_data_syms(rx_ant,:,:) = freq_data;
end
freq_tr_syms = tmp_freq_tr;
freq_data_syms = tmp_data_syms;