ed_decoder.m

一个UWB仿真程序包

%
%
%
function [demod_bit] = ...
    ed_decoder(rx_data, ths, ...
               symbol_start, ...
               burstlength,samples_per_burst,samples_per_symbol, ...
               channel_mask, channel_mask_unit, ...
               timing_offset_samples, ...
               PACKET_LENGTH, FS_CONT, T_INT, N_INT)
  
  % Get the signal only where necessary
  % Note: timing_offset_samples is in FS_CONT units
  burst_start_0 = symbol_start + ths*samples_per_burst + timing_offset_samples;
  burst_start_1 = burst_start_0 + (samples_per_symbol/2);

  % Energy detection receiver and decoding
  if isempty(channel_mask)
    n = burstlength-rem(burstlength,T_INT*FS_CONT*N_INT);
  else
    n = round(length(channel_mask)*channel_mask_unit*FS_CONT);
  end

  signal_idx_0 = repmat(burst_start_0,n,1)+repmat((0:n-1)',1,PACKET_LENGTH) + 1;
  signal_idx_1 = signal_idx_0 + samples_per_symbol/2 + 1;
  
  % Energy receiver
  [rx_down_0,samples_per_tint] = ...
      ed_receiver(rx_data(reshape(signal_idx_0,1, PACKET_LENGTH*n)),T_INT, ...
                  FS_CONT,N_INT,-1);
  [rx_down_1,samples_per_tint] = ...
      ed_receiver(rx_data(reshape(signal_idx_1,1, PACKET_LENGTH*n)),T_INT, ...
                  FS_CONT,N_INT,-1);
 
  % Apply the channel mask
  if ~isempty(channel_mask)
    channel_mask_long = repmat(channel_mask,1,PACKET_LENGTH);
    rx_down_1 = rx_down_1.*channel_mask_long;
    rx_down_0 = rx_down_0.*channel_mask_long;
  end

  % Decision rule and detection
  rx_down = ...
      sum(reshape((rx_down_0 - rx_down_1),n/(T_INT*FS_CONT*N_INT),PACKET_LENGTH), 1);

  idx_dec0 = find(rx_down>0);
  idx_dec1 = find(rx_down<0);
  idx_unknown = find(rx_down==0);

  demod_bit = [];
  demod_bit(idx_dec0) = 0;
  demod_bit(idx_dec1) = 1;
  demod_bit(idx_unknown) = round(rand(1,length(idx_unknown)));

return;