data_sim_154a.m

一个UWB仿真程序包

%
%
clear all, close all;
%
% Necessary path
addpath ./../rng;
addpath ./../util;
addpath ./../signal;
addpath ./../receiver;
addpath ./../data_signal;
addpath ./../reed_solomon;
addpath ./../preamble_signal;
addpath ../../src/channel;
addpath ../../src/scrambling_timehopping;


% Simulation parameters
PLOT_DEBUG  = 0;
FS_CONT     = 10e9;
RSCODE  = 1;
if RSCODE == 1
  DATA_LENGTH = 870;
  fullblock = floor(DATA_LENGTH/330);
  PACKET_LENGTH = fullblock*378 + (DATA_LENGTH-fullblock*330) + 48;
else
  DATA_LENGTH = 127*8;
  PACKET_LENGTH = DATA_LENGTH;
end
Npacket      = 1;
% Physical layer
TC            = 2e-9; % Chip length in seconds
BURST_LENGTH  = 4; % LPRF, in chip
%BURST_LENGTH  = 16; % HPRF, in chip
SYMBOL_LENGTH = 512; % In chip
% Multipath channel
CH_MODEL       = 1;
CH_ATT_THLD_DB = 30; %rays with bigger attenuation are considered 0
CH_RNG_SEED    = sum(100*clock);

%group all the parameters corresponding to the channel
channel_p = group_channel_params(CH_RNG_SEED,CH_MODEL,CH_ATT_THLD_DB,0.5,1e-9);

% Bandwidth of the noise
snr_dB = 16;
snr    = 10.^(snr_dB/10);
Eb     = 1;
s2     = Eb ./ (2*snr);
B      = 2e9;
% Receiver
T_INT = 1e-9;
N_INT = 8;
% Result from the timing synchronization and from the channel
% estimation
% $$$ channel_mask       = [];
% $$$ channel_mask       = ones(1,16);
% $$$ channel_mask_unit  = 8e-9; % Duration in seconds of a channel mask
% $$$                            % sample
% $$$ channel_mask_unit  = T_INT*N_INT;
timing_offset      = 0;  % In seconds
timing_offset_samples = timing_offset*FS_CONT;

t0 = clock;

% Pre-construction of the data signal of interest
samples = get_samples_values(TC,FS_CONT, ...
                                BURST_LENGTH, ...
                                SYMBOL_LENGTH, ...
                                PACKET_LENGTH);

[ep] = get_ep(PACKET_LENGTH, ...
              SYMBOL_LENGTH, ...
              BURST_LENGTH, ...
              samples);

symbol_start = get_symbol_start(PACKET_LENGTH,samples);

[burst, compound_channel, burstlength] ...
    = init_data_signal(FS_CONT, PACKET_LENGTH, TC,BURST_LENGTH,SYMBOL_LENGTH, ...
                       ep.ths, ep.scrambling, samples, ...
                       channel_p);

% Parameters for the generation of the Gaussian noise
ALPHA = PACKET_LENGTH/2;
Ts    = TC * SYMBOL_LENGTH;
Nt    = Ts * FS_CONT;

% Fake estimation of the channel mask
L             = 64;
CODE_ID       = 5;
preamble_code = abs(len31_preamble_code(CODE_ID));
channel_mask  = fake_estimate_channel(TC,FS_CONT,samples,...
				      L,preamble_code,CODE_ID,...
				      compound_channel,...
				      T_INT,N_INT,...
				      s2,B);
channel_mask  = channel_mask';
channel_mask_unit  = T_INT*N_INT;

%
for l = 1:Npacket
  fprintf('Packet %d, ',l);

  % Get the data bit (coded or uncoded)
  [tx_bit,data_bit] =  get_tx_bit(DATA_LENGTH,RSCODE,ep.interleaver_seed);

  % Get the data signal of interest
  [rx_data, signal_start] ... 
      = get_data_signal(PACKET_LENGTH, ...
                        samples.burst, samples.symbol, burstlength, ...
                        burst,ep.ths,symbol_start,tx_bit);

  % Add AWGN
  fprintf('add noise, ');
  [noise_0 noise_1] = randn_bl(ALPHA,Ts,Nt,B,s2*(2*B)/FS_CONT);
  rx_data = rx_data + [noise_0 noise_1];
  clear noise_0 noise_1;

  % Receiver
  %
  fprintf('receive\n');
  demod_bit = ed_decoder(rx_data, ep.ths, ...
                         symbol_start, ...
                         burstlength,samples.burst,samples.symbol, ...
                         channel_mask, channel_mask_unit, ...
                         timing_offset_samples, ...
                         PACKET_LENGTH, FS_CONT, T_INT, N_INT);

  if RSCODE == 1
    % RS decoding
    dec_bit = rs_decoder_154a(demod_bit,ep.interleaver_seed);
  else
    dec_bit = demod_bit;
  end

  % Compute the BER
  [num_err(l),ber_sim(l)] = symerr(data_bit,dec_bit);

end

dt=etime(clock,t0);
fprintf('(dt = %.2f), ber = %.12f\n',dt,mean(ber_sim));