void LiquidOfdmModComponent::initialize()
{
// print capabilities of liquid
if (debug_x) {
liquid_print_modulation_schemes();
liquid_print_fec_schemes();
liquid_print_crc_schemes();
}
// initialize subcarrier allocation
unsigned char p[noSubcarriers_x];
ofdmframe_init_default_sctype(noSubcarriers_x, p);
// create frame generator properties object and initialize to default
ofdmflexframegenprops_s fgProps;
ofdmflexframegenprops_init_default(&fgProps);
modulation_scheme ms = liquid_getopt_str2mod(modulationScheme_x.c_str());
fec_scheme fec0 = liquid_getopt_str2fec(fecZero_x.c_str());
fec_scheme fec1 = liquid_getopt_str2fec(fecOne_x.c_str());
crc_scheme check = liquid_getopt_str2crc(crcScheme_x.c_str());
fgProps.mod_scheme = ms;
fgProps.fec0 = fec0;
fgProps.fec1 = fec1;
fgProps.check = check;
gain_factor_ = powf(10.0f, gain_x/20.0f);
// create frame generator object
try {
frameGenerator_ = ofdmflexframegen_create(noSubcarriers_x, cyclicPrefixLength_x, taperLength_x, p, &fgProps);
ofdmflexframegen_print(frameGenerator_);
}
catch(...)
{
LOG(LERROR) << "Unexpected exception caught during frame generator generation";
}
}
void LiquidOfdmModComponent::parameterHasChanged(std::string name)
{
ofdmflexframegenprops_s fgProps;
ofdmflexframegen_getprops(frameGenerator_, &fgProps);
if (name == "modulation") {
modulation_scheme ms = liquid_getopt_str2mod(modulationScheme_x.c_str());
fgProps.mod_scheme = ms;
}
if (name == "fec0") {
fec_scheme fec0 = liquid_getopt_str2fec(fecZero_x.c_str());
fgProps.fec0 = fec0;
}
if (name == "fec1") {
fec_scheme fec1 = liquid_getopt_str2fec(fecOne_x.c_str());
fgProps.fec1 = fec1;
}
if (name == "crc") {
crc_scheme check = liquid_getopt_str2crc(crcScheme_x.c_str());
fgProps.check = check;
}
ofdmflexframegen_setprops(frameGenerator_, &fgProps);
if (name == "gain") {
gain_factor_ = powf(10.0f, gain_x/20.0f);
}
if (name == "subcarriers" ||
name == "prefixlength" ||
name == "taperlength")
{
//Need to destroy and recreate the frame generator
if (frameGenerator_)
ofdmflexframegen_destroy(frameGenerator_);
initialize();
}
}
int main(int argc, char*argv[])
{
// set random number generator seed
srand(time(NULL));
// options
unsigned int M = 64; // number of subcarriers
unsigned int cp_len = 16; // cyclic prefix length
modulation_scheme ms = LIQUID_MODEM_BPSK;
float SNRdB = 6.5f; // signal-to-noise ratio [dB]
unsigned int hc_len = 1; // channel impulse response length
unsigned int num_symbols = 40; // number of OFDM symbols
// get options
int dopt;
while((dopt = getopt(argc,argv,"hs:M:C:m:n:c:")) != EOF){
switch (dopt) {
case 'h': usage(); return 0;
case 's': SNRdB = atof(optarg); break;
case 'M': M = atoi(optarg); break;
case 'C': cp_len = atoi(optarg); break;
case 'm':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported mod. scheme: %s\n", argv[0], optarg);
exit(-1);
}
break;
case 'n': num_symbols = atoi(optarg); break;
case 'c': hc_len = atoi(optarg); break;
default:
exit(-1);
}
}
unsigned int i;
// validate options
if (M < 4) {
fprintf(stderr,"error: %s, must have at least 4 subcarriers\n", argv[0]);
exit(1);
} else if (hc_len == 0) {
fprintf(stderr,"error: %s, must have at least 1 channel tap\n", argv[0]);
exit(1);
}
// derived values
unsigned int symbol_len = M + cp_len;
float nstd = powf(10.0f, -SNRdB/20.0f);
float fft_gain = 1.0f / sqrtf(M); // 'gain' due to taking FFT
// buffers
unsigned int sym_in[M]; // input data symbols
unsigned int sym_out[M]; // output data symbols
float complex x[M]; // time-domain buffer
float complex X[M]; // freq-domain buffer
float complex buffer[symbol_len]; //
// create modulator/demodulator objects
modem mod = modem_create(ms);
modem demod = modem_create(ms);
unsigned int bps = modem_get_bps(mod); // modem bits/symbol
// create channel filter (random taps)
float complex hc[hc_len];
hc[0] = 1.0f;
for (i=1; i<hc_len; i++)
hc[i] = 0.1f * (randnf() + _Complex_I*randnf());
firfilt_cccf fchannel = firfilt_cccf_create(hc, hc_len);
//
unsigned int n;
unsigned int num_bit_errors = 0;
for (n=0; n<num_symbols; n++) {
// generate random data symbols and modulate onto subcarriers
for (i=0; i<M; i++) {
sym_in[i] = rand() % (1<<bps);
modem_modulate(mod, sym_in[i], &X[i]);
}
// run inverse transform
fft_run(M, X, x, LIQUID_FFT_BACKWARD, 0);
// scale by FFT gain so E{|x|^2} = 1
for (i=0; i<M; i++)
x[i] *= fft_gain;
// apply channel impairments
for (i=0; i<M + cp_len; i++) {
// push samples through channel filter, starting with cyclic prefix
firfilt_cccf_push(fchannel, x[(M-cp_len+i)%M]);
// compute output
firfilt_cccf_execute(fchannel, &buffer[i]);
// add noise
buffer[i] += nstd*( randnf() + _Complex_I*randnf() ) * M_SQRT1_2;
}
// run forward transform
fft_run(M, &buffer[cp_len], X, LIQUID_FFT_FORWARD, 0);
// TODO : apply equalizer to 'X' here
// demodulate and compute bit errors
for (i=0; i<M; i++) {
// scale by fft size
X[i] *= fft_gain;
modem_demodulate(demod, X[i], &sym_out[i]);
num_bit_errors += liquid_count_ones(sym_in[i] ^ sym_out[i]);
}
}
// destroy objects
modem_destroy(mod);
modem_destroy(demod);
firfilt_cccf_destroy(fchannel);
// print results
unsigned int total_bits = M*bps*num_symbols;
float ber = (float)num_bit_errors / (float)total_bits;
printf(" bit errors : %6u / %6u (%12.4e)\n", num_bit_errors, total_bits, ber);
printf("done.\n");
return 0;
}
int main(int argc, char*argv[]) {
// create mod/demod objects
float gnuplot_version=0.0;
enum {GNUPLOT_TERM_PNG=0,
GNUPLOT_TERM_JPG,
GNUPLOT_TERM_EPS
} gnuplot_term = 0;
char input_filename[256] = "datafile.dat";
char output_filename[256] = "modem.gnu";
//char figure_title[256] = "constellation";
modulation_scheme ms = LIQUID_MODEM_QPSK;
int dopt;
while ((dopt = getopt(argc,argv,"uhg:t:d:f:m:")) != EOF) {
switch (dopt) {
case 'u':
case 'h':
usage();
return 0;
case 'g': gnuplot_version = atof(optarg); break;
case 't': gnuplot_term = atoi(optarg); break;
case 'd': strncpy(input_filename,optarg,256); break;
case 'f': strncpy(output_filename,optarg,256); break;
case 'm':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported modulation scheme \"%s\"\n", argv[0], optarg);
return 1;
}
break;
default:
exit(1);
}
}
// TODO : validate input
if (ms == LIQUID_MODEM_UNKNOWN || ms >= LIQUID_MODEM_NUM_SCHEMES) {
fprintf(stderr,"error: %s, invalid modulation scheme \n", argv[0]);
return 1;
}
// derived options/values
unsigned int bps = modulation_types[ms].bps;
int plot_labels = (gnuplot_version > 4.1) && (bps < 8);
int plot_long_labels = 0;
unsigned int i;
// generate modem, compute constellation, derive plot style accordingly
unsigned int M = 1<<bps;
float complex constellation[M];
modem q = modem_create(ms);
for (i=0; i<M; i++)
modem_modulate(q, i, &constellation[i]);
modem_destroy(q);
float range = 1.5f;
enum {AXES_POLAR, AXES_CART} axes = AXES_POLAR;
switch (ms) {
// Phase-shift keying (PSK)
case LIQUID_MODEM_PSK2:
case LIQUID_MODEM_PSK4:
case LIQUID_MODEM_PSK8:
case LIQUID_MODEM_PSK16:
case LIQUID_MODEM_PSK32:
case LIQUID_MODEM_PSK64:
case LIQUID_MODEM_PSK128:
case LIQUID_MODEM_PSK256:
// Differential phase-shift keying (DPSK)
case LIQUID_MODEM_DPSK2:
case LIQUID_MODEM_DPSK4:
case LIQUID_MODEM_DPSK8:
case LIQUID_MODEM_DPSK16:
case LIQUID_MODEM_DPSK32:
case LIQUID_MODEM_DPSK64:
case LIQUID_MODEM_DPSK128:
case LIQUID_MODEM_DPSK256:
range = 1.2f;
axes = AXES_POLAR;
break;
// amplitude-shift keying (ASK)
case LIQUID_MODEM_ASK2: range = 1.2f; axes = AXES_CART; break;
case LIQUID_MODEM_ASK4: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_ASK8: range = 1.75f; axes = AXES_CART; break;
case LIQUID_MODEM_ASK16: range = 2.00f; axes = AXES_CART; break;
case LIQUID_MODEM_ASK32: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_ASK64: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_ASK128: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_ASK256: range = 1.5f; axes = AXES_CART; break;
// rectangular quadrature amplitude-shift keying (QAM)
case LIQUID_MODEM_QAM4: range = 1.75f; axes = AXES_CART; break;
case LIQUID_MODEM_QAM8: range = 1.75f; axes = AXES_CART; break;
case LIQUID_MODEM_QAM16: range = 1.75f; axes = AXES_CART; break;
case LIQUID_MODEM_QAM32: range = 1.75f; axes = AXES_CART; break;
case LIQUID_MODEM_QAM64: range = 1.75f; axes = AXES_CART; break;
case LIQUID_MODEM_QAM128: range = 1.75f; axes = AXES_CART; break;
case LIQUID_MODEM_QAM256: range = 1.75f; axes = AXES_CART; break;
// amplitude phase-shift keying (APSK)
case LIQUID_MODEM_APSK4: range = 1.5f; axes = AXES_POLAR; break;
case LIQUID_MODEM_APSK8: range = 1.5f; axes = AXES_POLAR; break;
case LIQUID_MODEM_APSK16: range = 1.5f; axes = AXES_POLAR; break;
case LIQUID_MODEM_APSK32: range = 1.5f; axes = AXES_POLAR; break;
case LIQUID_MODEM_APSK64: range = 1.5f; axes = AXES_POLAR; break;
case LIQUID_MODEM_APSK128: range = 1.5f; axes = AXES_POLAR; break;
case LIQUID_MODEM_APSK256: range = 1.5f; axes = AXES_POLAR; break;
// specific modems
case LIQUID_MODEM_BPSK: range = 1.5f; axes = AXES_POLAR; break;
case LIQUID_MODEM_QPSK: range = 1.5f; axes = AXES_POLAR; break;
case LIQUID_MODEM_OOK: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_SQAM32: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_SQAM128: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_V29: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_ARB16OPT: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_ARB32OPT: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_ARB64OPT: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_ARB128OPT: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_ARB256OPT: range = 1.5f; axes = AXES_CART; break;
case LIQUID_MODEM_ARB64VT: range = 2.0f; axes = AXES_CART; break;
default:
fprintf(stderr,"error: %s, invalid modulation scheme\n", argv[0]);
exit(1);
}
// determine minimum distance between any two points
float dmin = 0.0f;
for (i=0; i<M; i++) {
unsigned int j;
for (j=i+1; j<M; j++) {
float d = cabsf(constellation[i] - constellation[j]);
if ( (d < dmin) || (i==0 && j==1) )
dmin = d;
}
}
plot_long_labels = dmin < 0.34 ? 0 : 1;
// write output file
FILE * fid = fopen(output_filename,"w");
if (fid == NULL) {
fprintf(stderr,"error: %s, could not open file \"%s\" for writing.\n", argv[0],output_filename);
exit(1);
}
// print header
fprintf(fid,"# %s : auto-generated file (do not edit)\n", output_filename);
fprintf(fid,"# invoked as :");
for (i=0; i<argc; i++)
fprintf(fid," %s",argv[i]);
fprintf(fid,"\n");
fprintf(fid,"reset\n");
fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n");
// TODO : set range according to scheme
fprintf(fid,"set xrange [-%4.2f:%4.2f]\n",range,range);
fprintf(fid,"set yrange [-%4.2f:%4.2f]\n",range,range);
fprintf(fid,"set size square\n");
//fprintf(fid,"set title \"%s\"\n", figure_title);
fprintf(fid,"set xlabel \"I\"\n");
fprintf(fid,"set ylabel \"Q\"\n");
fprintf(fid,"set nokey # disable legned\n");
// TODO : set grid type (e.g. polar) according to scheme
//
if (axes == AXES_POLAR)
fprintf(fid,"set grid polar\n");
else
fprintf(fid,"set grid xtics ytics\n");
fprintf(fid,"set grid linetype 1 linecolor rgb '%s' linewidth 1\n",LIQUID_DOC_COLOR_GRID);
fprintf(fid,"set pointsize 1.0\n");
if (!plot_labels) {
// do not print labels
fprintf(fid,"plot '%s' using 1:2 with points pointtype 7 linecolor rgb '#004080'\n",input_filename);
} else {
// print labels
fprintf(fid,"xoffset = %8.6f\n", plot_long_labels ? 0.0 : 0.045f);
fprintf(fid,"yoffset = %8.6f\n", plot_long_labels ? 0.06f : 0.045f);
unsigned int label_line = plot_long_labels ? 3 : 4;
fprintf(fid,"plot '%s' using 1:2 with points pointtype 7 linecolor rgb '#004080',\\\n",input_filename);
fprintf(fid," '%s' using ($1+xoffset):($2+yoffset):%u with labels font 'arial,10'\n", input_filename,label_line);
}
// close it up
fclose(fid);
return 0;
}
int main(int argc, char*argv[])
{
srand( time(NULL) );
// options
int verbose = 1;
int which_ber_per = ESTIMATE_SNR_BER;
int which_snr_ebn0 = ESTIMATE_SNR;
float error_rate = 1e-3f;
unsigned int frame_len = 1024;
unsigned long int max_trials = 0;
modulation_scheme ms = LIQUID_MODEM_QPSK;
fec_scheme fec0 = LIQUID_FEC_NONE; // inner code
fec_scheme fec1 = LIQUID_FEC_NONE; // outer code
int soft_decoding = 0;
int dopt;
while ((dopt = getopt(argc,argv,"uhvqBPseSHE:n:x:c:m:")) != EOF) {
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 'v': verbose = 1; break;
case 'q': verbose = 0; break;
case 'B': which_ber_per = ESTIMATE_SNR_BER; break;
case 'P': which_ber_per = ESTIMATE_SNR_PER; break;
case 's': which_snr_ebn0 = ESTIMATE_SNR; break;
case 'e': which_snr_ebn0 = ESTIMATE_EBN0; break;
case 'S': soft_decoding = 1; break;
case 'H': soft_decoding = 0; break;
case 'E': error_rate = atof(optarg); break;
case 'n': frame_len = atoi(optarg); break;
case 'x': max_trials = atoi(optarg); break;
case 'c':
// FEC scheme
fec0 = liquid_getopt_str2fec(optarg);
if (fec0 == LIQUID_FEC_UNKNOWN) {
fprintf(stderr,"error: unknown/unsupported inner FEC scheme \"%s\"\n\n",optarg);
exit(1);
}
break;
case 'm':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: modem_example, unknown/unsupported modulation scheme \"%s\"\n", optarg);
return 1;
}
break;
default:
exit(1);
}
}
// validate input
if (error_rate <= 0.0f) {
fprintf(stderr,"error: error rate must be greater than 0\n");
exit(1);
} else if (frame_len == 0 || frame_len > 10000) {
fprintf(stderr,"error: frame length must be in [1, 10,000]\n");
exit(1);
} else if (which_ber_per == ESTIMATE_SNR_BER && error_rate >= 0.5) {
fprintf(stderr,"error: error rate must be less than 0.5 when simulating BER\n");
exit(1);
} else if (error_rate >= 1.0f) {
fprintf(stderr,"error: error rate must be less than 1\n");
exit(1);
}
if (max_trials == 0) {
// unspecified: use defaults
if (which_ber_per == ESTIMATE_SNR_BER)
max_trials = 800000;
else
max_trials = 200;
}
simulate_per_opts opts;
opts.ms = ms;
opts.fec0 = fec0;
opts.fec1 = fec1;
opts.dec_msg_len = frame_len;
opts.soft_decoding = soft_decoding;
unsigned int bps = modulation_types[ms].bps;
// minimum number of errors to simulate
opts.min_packet_errors = which_ber_per==ESTIMATE_SNR_PER ? 10 : 0;
opts.min_bit_errors = which_ber_per==ESTIMATE_SNR_BER ? 50 : 0;
// minimum number of trials to simulate
opts.min_packet_trials = which_ber_per==ESTIMATE_SNR_PER ? 500 : 0;
opts.min_bit_trials = which_ber_per==ESTIMATE_SNR_BER ? 5000 : 0;
// maximum number of trials to simulate (before bailing and
// deeming simulation unsuccessful)
opts.max_packet_trials = which_ber_per==ESTIMATE_SNR_PER ? max_trials : -1;
opts.max_bit_trials = which_ber_per==ESTIMATE_SNR_BER ? max_trials : -1;
// estimate SNR for a specific PER
printf("%u-%s // %s // %s (%s: %e)\n", 1<<bps,
modulation_types[opts.ms].name,
fec_scheme_str[opts.fec0][0],
fec_scheme_str[opts.fec1][0],
which_ber_per == ESTIMATE_SNR_BER ? "BER" : "PER",
error_rate);
// run estimation
float x_hat = estimate_snr(opts, which_ber_per, which_snr_ebn0, error_rate);
// compute rate [b/s/Hz]
float rate = bps * fec_get_rate(opts.fec0) * fec_get_rate(opts.fec1);
// set estimated values
float SNRdB_hat;
float EbN0dB_hat;
if (which_snr_ebn0==ESTIMATE_SNR) {
SNRdB_hat = x_hat;
EbN0dB_hat = SNRdB_hat - 10*log10f(rate);
} else {
SNRdB_hat = x_hat + 10*log10f(rate);
EbN0dB_hat = x_hat;
}
if (verbose) {
printf("++ SNR (est) : %8.4fdB (Eb/N0 = %8.4fdB) for %s: %12.4e\n",
SNRdB_hat,
EbN0dB_hat,
which_ber_per == ESTIMATE_SNR_BER ? "BER" : "PER",
error_rate);
}
printf("done.\n");
return 0;
}
int main(int argc, char*argv[])
{
//srand(time(NULL));
// options
unsigned int M = 64; // number of subcarriers
unsigned int cp_len = 16; // cyclic prefix length
unsigned int taper_len = 4; // taper length
unsigned int payload_len = 120; // length of payload (bytes)
modulation_scheme ms = LIQUID_MODEM_QPSK; // modulation scheme
fec_scheme fec0 = LIQUID_FEC_NONE; // inner code
fec_scheme fec1 = LIQUID_FEC_HAMMING128; // outer code
crc_scheme check = LIQUID_CRC_32; // validity check
float noise_floor = -80.0f; // noise floor [dB]
float SNRdB = 20.0f; // signal-to-noise ratio [dB]
float dphi = 0.02f; // carrier frequency offset
int debug = 0; // enable debugging?
// get options
int dopt;
while((dopt = getopt(argc,argv,"uhds:F:M:C:n:m:v:c:k:")) != EOF){
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 'd': debug = 1; break;
case 's': SNRdB = atof(optarg); break;
case 'F': dphi = atof(optarg); break;
case 'M': M = atoi(optarg); break;
case 'C': cp_len = atoi(optarg); break;
case 'n': payload_len = atol(optarg); break;
case 'm': ms = liquid_getopt_str2mod(optarg); break;
case 'v': check = liquid_getopt_str2crc(optarg); break;
case 'c': fec0 = liquid_getopt_str2fec(optarg); break;
case 'k': fec1 = liquid_getopt_str2fec(optarg); break;
default:
exit(-1);
}
}
unsigned int i;
// TODO : validate options
// derived values
unsigned int buf_len = 256;
float complex buf[buf_len]; // time-domain buffer
// allocate memory for header, payload
unsigned char header[8];
unsigned char payload[payload_len];
// create frame generator
ofdmflexframegenprops_s fgprops;
ofdmflexframegenprops_init_default(&fgprops);
fgprops.check = check;
fgprops.fec0 = fec0;
fgprops.fec1 = fec1;
fgprops.mod_scheme = ms;
ofdmflexframegen fg = ofdmflexframegen_create(M, cp_len, taper_len, NULL, &fgprops);
// create frame synchronizer
ofdmflexframesync fs = ofdmflexframesync_create(M, cp_len, taper_len, NULL, callback, (void*)payload);
if (debug)
ofdmflexframesync_debug_enable(fs);
// initialize header/payload and assemble frame
for (i=0; i<8; i++)
header[i] = i & 0xff;
for (i=0; i<payload_len; i++)
payload[i] = rand() & 0xff;
ofdmflexframegen_assemble(fg, header, payload, payload_len);
ofdmflexframegen_print(fg);
ofdmflexframesync_print(fs);
// create channel and add impairments
channel_cccf channel = channel_cccf_create();
channel_cccf_add_awgn(channel, noise_floor, SNRdB);
channel_cccf_add_carrier_offset(channel, dphi, 0.0f);
// generate frame, push through channel
int last_symbol=0;
while (!last_symbol) {
// generate symbol
last_symbol = ofdmflexframegen_write(fg, buf, buf_len);
// apply channel to buffer (in place)
channel_cccf_execute_block(channel, buf, buf_len, buf);
// push samples through synchronizer
ofdmflexframesync_execute(fs, buf, buf_len);
}
// export debugging file
if (debug)
ofdmflexframesync_debug_print(fs, "ofdmflexframesync_debug.m");
// destroy objects
ofdmflexframegen_destroy(fg);
ofdmflexframesync_destroy(fs);
channel_cccf_destroy(channel);
printf("done.\n");
return 0;
}
int main(int argc, char*argv[]) {
srand( time(NULL) );
// options
simulate_per_opts opts;
opts.ms = LIQUID_MODEM_BPSK;
opts.bps = 1;
opts.fec0 = LIQUID_FEC_NONE;
opts.fec1 = LIQUID_FEC_NONE;
opts.dec_msg_len = 1024;
opts.soft_decoding = 1;
opts.min_packet_errors = 5;
opts.min_bit_errors = 10;
opts.min_packet_trials = 50;
opts.min_bit_trials = 10000;
opts.max_packet_trials = 1000;
opts.max_bit_trials = 1000000;
// read command-line options
int dopt;
while((dopt = getopt(argc,argv,"uhn:p:m:c:k:SH")) != EOF){
switch (dopt) {
case 'h':
case 'u': usage(); return 0;
case 'n': opts.dec_msg_len = atoi(optarg); break;
case 'p': opts.bps = atoi(optarg); break;
case 'm':
opts.ms = liquid_getopt_str2mod(optarg);
if (opts.ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: modem_example, unknown/unsupported modulation scheme \"%s\"\n", optarg);
exit(1);
}
break;
case 'c':
// inner FEC scheme
opts.fec0 = liquid_getopt_str2fec(optarg);
if (opts.fec0 == LIQUID_FEC_UNKNOWN) {
fprintf(stderr,"error: unknown/unsupported modulation scheme \"%s\"\n\n",optarg);
exit(-1);
}
break;
case 'k':
// outer FEC scheme
opts.fec1 = liquid_getopt_str2fec(optarg);
if (opts.fec1 == LIQUID_FEC_UNKNOWN) {
fprintf(stderr,"error: unknown/unsupported modulation scheme \"%s\"\n\n",optarg);
exit(-1);
}
break;
case 'S': opts.soft_decoding = 1; break;
case 'H': opts.soft_decoding = 0; break;
default:
exit(1);
}
}
// SNR range, steps
float SNRdB_min = 0.0f;
float SNRdB_max = 20.0f;
unsigned int num_steps = 21;
// derived values
float SNRdB_step = (SNRdB_max - SNRdB_min)/(float)(num_steps-1);
//
float SNRdB;
// generate results structure
simulate_per_results results;
// array for BER
float BER[num_steps];
unsigned int i;
for (i=0; i<num_steps; i++) {
SNRdB = SNRdB_min + i*SNRdB_step;
simulate_per(opts, SNRdB, &results);
//printf(" %12.8f : %12.4e\n", SNRdB, PER);
printf(" %c SNR: %6.2f, bits: %8lu / %8lu (%12.4e), packets: %6lu / %6lu (%6.2f%%)\n",
results.success ? '*' : ' ',
SNRdB,
results.num_bit_errors, results.num_bit_trials, results.BER,
results.num_packet_errors, results.num_packet_trials, results.PER*100.0f);
// save BER in array
BER[i] = results.BER;
}
//
// export data
//
FILE * fid = fopen(OUTPUT_FILENAME,"w");
if (!fid) {
fprintf(stderr,"error: %s, could not open '%s' for writing\n", argv[0], OUTPUT_FILENAME);
exit(1);
}
fprintf(fid,"%% %s : auto-generated file\n", OUTPUT_FILENAME);
fprintf(fid,"clear all;\n");
fprintf(fid,"close all;\n");
for (i=0; i<num_steps; i++) {
fprintf(fid,"SNRdB(%3u) = %12.8f;\n", i+1, SNRdB_min + i*SNRdB_step);
fprintf(fid,"BER(%3u) = %12.4e;\n", i+1, BER[i]);
}
fprintf(fid,"\n\n");
fprintf(fid,"figure;\n");
fprintf(fid,"semilogy(SNRdB, 0.5*erfc(sqrt(10.^[SNRdB/10]))+1e-12,'-x',\n");
fprintf(fid," SNRdB, BER + 1e-12, '-x');\n");
fprintf(fid,"axis([%f %f 1e-6 1]);\n", SNRdB_min, SNRdB_max);
fprintf(fid,"xlabel('SNR [dB]');\n");
fprintf(fid,"ylabel('Bit Error Rate');\n");
fprintf(fid,"legend('uncoded BPSK','modem: %s (M=%u) // fec: %s',1);\n",
modulation_types[opts.ms].name, 1<<opts.bps, fec_scheme_str[opts.fec0][0]);
fprintf(fid,"grid on;\n");
fclose(fid);
printf("results written to '%s'\n", OUTPUT_FILENAME);
printf("done.\n");
return 0;
}
int main(int argc, char*argv[])
{
// create mod/demod objects
modulation_scheme ms = LIQUID_MODEM_ARB64VT;
modulation_scheme mref = LIQUID_MODEM_QAM64;
float alpha = 1.0f;
int dopt;
while ((dopt = getopt(argc,argv,"uhp:m:r:a:")) != EOF) {
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 'm':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported modulation scheme '%s'\n", argv[0], optarg);
return 1;
}
break;
case 'r':
mref = liquid_getopt_str2mod(optarg);
if (mref == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported modulation scheme '%s'\n", argv[0], optarg);
return 1;
}
break;
case 'a': alpha = atof(optarg); break;
default:
exit(1);
}
}
// validate input
unsigned int i;
unsigned int j;
// initialize reference points
modem qref = modem_create(mref);
unsigned int kref = modem_get_bps(qref);
unsigned int p = 1 << kref;
float complex cref[p];
for (i=0; i<p; i++) {
modem_modulate(qref, i, &cref[i]);
cref[i] *= alpha;
}
modem_destroy(qref);
// generate the constellation
modem q = modem_create(ms);
unsigned int bps = modem_get_bps(q);
unsigned int M = 1 << bps;
float complex constellation[M];
for (i=0; i<M; i++)
modem_modulate(q, i, &constellation[i]);
modem_destroy(q);
// perform search
unsigned char * link = NULL;
unsigned int num_unassigned=M;
unsigned char unassigned[M];
unsigned int s=0; // number of points per reference
// run search until all points are found
do {
// increment number of points per reference
s++;
// reallocte memory for links
link = (unsigned char*) realloc(link, p*s);
// search for nearest constellation points to reference points
modem_arbref_search(constellation, M, cref, p, link, s);
// find unassigned constellation points
num_unassigned = modem_arbref_search_unassigned(link,M,p,s,unassigned);
printf("%3u : number of unassigned points: %3u / %3u\n", s, num_unassigned, M);
} while (num_unassigned > 0);
// print table
printf("\n");
printf("unsigned char modem_demodulate_gentab[%u][%u] = {\n", p, s);
for (i=0; i<p; i++) {
printf(" {");
for (j=0; j<s; j++) {
printf("%3u%s", link[i*s+j], j==(s-1) ? "" : ",");
}
printf("}%s", i==(p-1) ? "};\n" : ",\n");
}
//
// export output file
//
FILE * fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s : auto-generated file\n", OUTPUT_FILENAME);
fprintf(fid,"clear all;\n");
fprintf(fid,"close all;\n");
fprintf(fid,"bps = %u;\n", bps);
fprintf(fid,"M = %u;\n", M);
fprintf(fid,"p = %u;\n", p);
fprintf(fid,"s = %u;\n", s);
// save constellation points
for (i=0; i<M; i++) {
fprintf(fid,"c(%3u) = %12.4e + j*%12.4e;\n", i+1,
crealf(constellation[i]),
cimagf(constellation[i]));
}
// save reference points
for (i=0; i<p; i++)
fprintf(fid,"cref(%3u) = %12.4e + j*%12.4e;\n", i+1, crealf(cref[i]), cimagf(cref[i]));
// save reference matrix
fprintf(fid,"link = zeros(p,s);\n");
for (i=0; i<p; i++) {
for (j=0; j<s; j++) {
fprintf(fid,"link(%3u,%3u) = %u;\n", i+1, j+1, link[i*s+j]+1);
}
}
// plot results
fprintf(fid,"figure;\n");
fprintf(fid,"plot(real(c), imag(c), 'bx',\n");
fprintf(fid," real(cref), imag(cref),'or');\n");
// draw lines between reference points and associated constellation points
fprintf(fid,"hold on;\n");
fprintf(fid," for i=1:p,\n");
fprintf(fid," for j=1:s,\n");
fprintf(fid," plot([real(cref(i)) real(c(link(i,j)))], [imag(cref(i)) imag(c(link(i,j)))], '-', 'Color', 0.8*[1 1 1]);\n");
fprintf(fid," end;\n");
fprintf(fid," end;\n");
fprintf(fid,"hold off;\n");
fprintf(fid,"xlabel('in-phase');\n");
fprintf(fid,"ylabel('quadrature phase');\n");
fprintf(fid,"%%legend('constellation','reference','links',0);\n");
fprintf(fid,"title(['Arbitrary ' num2str(M) '-QAM']);\n");
fprintf(fid,"axis([-1 1 -1 1]*1.9);\n");
fprintf(fid,"axis square;\n");
fprintf(fid,"grid on;\n");
fclose(fid);
printf("results written to '%s'\n", OUTPUT_FILENAME);
printf("done.\n");
// free allocated memory
free(link);
return 0;
}
int main(int argc, char *argv[])
{
//srand( time(NULL) );
// options
modulation_scheme ms = LIQUID_MODEM_QPSK; // mod. scheme
crc_scheme check = LIQUID_CRC_32; // data validity check
fec_scheme fec0 = LIQUID_FEC_NONE; // fec (inner)
fec_scheme fec1 = LIQUID_FEC_NONE; // fec (outer)
unsigned int payload_len = 120; // payload length
int debug_enabled = 0; // enable debugging?
float noise_floor = -60.0f; // noise floor
float SNRdB = 20.0f; // signal-to-noise ratio
float dphi = 0.01f; // carrier frequency offset
// get options
int dopt;
while((dopt = getopt(argc,argv,"uhs:F:n:m:v:c:k:d")) != EOF){
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 's': SNRdB = atof(optarg); break;
case 'F': dphi = atof(optarg); break;
case 'n': payload_len = atol(optarg); break;
case 'm': ms = liquid_getopt_str2mod(optarg); break;
case 'v': check = liquid_getopt_str2crc(optarg); break;
case 'c': fec0 = liquid_getopt_str2fec(optarg); break;
case 'k': fec1 = liquid_getopt_str2fec(optarg); break;
case 'd': debug_enabled = 1; break;
default:
exit(-1);
}
}
// derived values
unsigned int i;
float nstd = powf(10.0f, noise_floor/20.0f); // noise std. dev.
float gamma = powf(10.0f, (SNRdB+noise_floor)/20.0f); // channel gain
// create flexframegen object
flexframegenprops_s fgprops;
flexframegenprops_init_default(&fgprops);
fgprops.mod_scheme = ms;
fgprops.check = check;
fgprops.fec0 = fec0;
fgprops.fec1 = fec1;
flexframegen fg = flexframegen_create(&fgprops);
// frame data (header and payload)
unsigned char header[14];
unsigned char payload[payload_len];
// create flexframesync object
flexframesync fs = flexframesync_create(callback,NULL);
if (debug_enabled)
flexframesync_debug_enable(fs);
// initialize header, payload
for (i=0; i<14; i++)
header[i] = i;
for (i=0; i<payload_len; i++)
payload[i] = rand() & 0xff;
// assemble the frame
flexframegen_assemble(fg, header, payload, payload_len);
flexframegen_print(fg);
// generate the frame in blocks
unsigned int buf_len = 256;
float complex x[buf_len];
float complex y[buf_len];
int frame_complete = 0;
float phi = 0.0f;
while (!frame_complete) {
// write samples to buffer
frame_complete = flexframegen_write_samples(fg, x, buf_len);
// add noise and push through synchronizer
for (i=0; i<buf_len; i++) {
// apply channel gain and carrier offset to input
y[i] = gamma * x[i] * cexpf(_Complex_I*phi);
phi += dphi;
// add noise
y[i] += nstd*( randnf() + _Complex_I*randnf())*M_SQRT1_2;
}
// run through frame synchronizer
flexframesync_execute(fs, y, buf_len);
}
// export debugging file
if (debug_enabled)
flexframesync_debug_print(fs, "flexframesync_debug.m");
flexframesync_print(fs);
// destroy allocated objects
flexframegen_destroy(fg);
flexframesync_destroy(fs);
printf("done.\n");
return 0;
}
int main(int argc, char*argv[]) {
srand( time(NULL) );
// parameters
float phase_offset = M_PI/10;
float frequency_offset = 0.001f;
float SNRdB = 30.0f;
float pll_bandwidth = 0.02f;
modulation_scheme ms = LIQUID_MODEM_QPSK;
unsigned int n=256; // number of iterations
int dopt;
while ((dopt = getopt(argc,argv,"uhs:b:n:P:F:m:")) != EOF) {
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 's': SNRdB = atof(optarg); break;
case 'b': pll_bandwidth = atof(optarg); break;
case 'n': n = atoi(optarg); break;
case 'P': phase_offset = atof(optarg); break;
case 'F': frequency_offset= atof(optarg); break;
case 'm':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported modulation scheme \"%s\"\n", argv[0], optarg);
return 1;
}
break;
default:
exit(1);
}
}
unsigned int d=n/32; // print every "d" lines
FILE * fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid, "%% %s : auto-generated file\n", OUTPUT_FILENAME);
fprintf(fid, "clear all;\n");
fprintf(fid, "phi=zeros(1,%u);\n",n);
fprintf(fid, "r=zeros(1,%u);\n",n);
// objects
nco_crcf nco_tx = nco_crcf_create(LIQUID_VCO);
nco_crcf nco_rx = nco_crcf_create(LIQUID_VCO);
modem mod = modem_create(ms);
modem demod = modem_create(ms);
unsigned int bps = modem_get_bps(mod);
// initialize objects
nco_crcf_set_phase(nco_tx, phase_offset);
nco_crcf_set_frequency(nco_tx, frequency_offset);
nco_crcf_pll_set_bandwidth(nco_rx, pll_bandwidth);
float noise_power = powf(10.0f, -SNRdB/20.0f);
// print parameters
printf("PLL example :\n");
printf("modem : %u-%s\n", 1<<bps, modulation_types[ms].name);
printf("frequency offset: %6.3f, phase offset: %6.3f, SNR: %6.2fdB, pll b/w: %6.3f\n",
frequency_offset, phase_offset, SNRdB, pll_bandwidth);
// run loop
unsigned int i, M=1<<bps, sym_in, sym_out, num_errors=0;
float phase_error;
float complex x, r, v, noise;
for (i=0; i<n; i++) {
// generate random symbol
sym_in = rand() % M;
// modulate
modem_modulate(mod, sym_in, &x);
// channel
//r = nco_crcf_cexpf(nco_tx);
nco_crcf_mix_up(nco_tx, x, &r);
// add complex white noise
crandnf(&noise);
r += noise * noise_power;
//
//v = nco_crcf_cexpf(nco_rx);
nco_crcf_mix_down(nco_rx, r, &v);
// demodulate
modem_demodulate(demod, v, &sym_out);
num_errors += count_bit_errors(sym_in, sym_out);
// error estimation
//phase_error = cargf(r*conjf(v));
phase_error = modem_get_demodulator_phase_error(demod);
// perfect error estimation
//phase_error = nco_tx->theta - nco_rx->theta;
// print every line in a format that octave can read
fprintf(fid, "phi(%u) = %10.6E;\n", i+1, phase_error);
fprintf(fid, "r(%u) = %10.6E + j*%10.6E;\n",
i+1, crealf(v), cimagf(v));
if ((i+1)%d == 0 || i==n-1) {
printf(" %4u: e_hat : %6.3f, phase error : %6.3f, freq error : %6.3f\n",
i+1, // iteration
phase_error, // estimated phase error
nco_crcf_get_phase(nco_tx) - nco_crcf_get_phase(nco_rx),// true phase error
nco_crcf_get_frequency(nco_tx) - nco_crcf_get_frequency(nco_rx)// true frequency error
);
}
// update tx nco object
nco_crcf_step(nco_tx);
// update pll
nco_crcf_pll_step(nco_rx, phase_error);
// update rx nco object
nco_crcf_step(nco_rx);
}
fprintf(fid, "figure;\n");
fprintf(fid, "plot(1:length(phi),phi,'LineWidth',2,'Color',[0 0.25 0.5]);\n");
fprintf(fid, "xlabel('Symbol Index');\n");
fprintf(fid, "ylabel('Phase Error [radians]');\n");
fprintf(fid, "grid on;\n");
fprintf(fid, "t0 = round(0.25*length(r));\n");
fprintf(fid, "figure;\n");
fprintf(fid, "plot(r(1:t0),'x','Color',[0.6 0.6 0.6],r(t0:end),'x','Color',[0 0.25 0.5]);\n");
fprintf(fid, "grid on;\n");
fprintf(fid, "axis([-1.5 1.5 -1.5 1.5]);\n");
fprintf(fid, "axis('square');\n");
fprintf(fid, "xlabel('In-Phase');\n");
fprintf(fid, "ylabel('Quadrature');\n");
fprintf(fid, "legend(['first 25%%'],['last 75%%'],1);\n");
fclose(fid);
printf("results written to %s.\n",OUTPUT_FILENAME);
nco_crcf_destroy(nco_tx);
nco_crcf_destroy(nco_rx);
modem_destroy(mod);
modem_destroy(demod);
printf("bit errors: %u / %u\n", num_errors, bps*n);
printf("done.\n");
return 0;
}
int main(int argc, char*argv[])
{
srand(time(NULL));
// options
unsigned int M = 64; // number of subcarriers
unsigned int cp_len = 16; // cyclic prefix length
unsigned int taper_len = 4; // taper length
unsigned int payload_len = 120; // length of payload (bytes)
modulation_scheme ms = LIQUID_MODEM_QPSK;
fec_scheme fec0 = LIQUID_FEC_NONE;
fec_scheme fec1 = LIQUID_FEC_HAMMING128;
crc_scheme check = LIQUID_CRC_32;
float noise_floor = -30.0f; // noise floor [dB]
float SNRdB = 20.0f; // signal-to-noise ratio [dB]
float dphi = 0.02f; // carrier frequency offset
int debug_enabled = 0; // enable debugging?
// get options
int dopt;
while((dopt = getopt(argc,argv,"uhds:F:M:C:n:m:v:c:k:")) != EOF){
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 'd': debug_enabled = 1; break;
case 's': SNRdB = atof(optarg); break;
case 'F': dphi = atof(optarg); break;
case 'M': M = atoi(optarg); break;
case 'C': cp_len = atoi(optarg); break;
case 'n': payload_len = atol(optarg); break;
case 'm':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported mod. scheme: %s\n", argv[0], optarg);
exit(-1);
}
break;
case 'v':
// data integrity check
check = liquid_getopt_str2crc(optarg);
if (check == LIQUID_CRC_UNKNOWN) {
fprintf(stderr,"error: unknown/unsupported CRC scheme \"%s\"\n\n",optarg);
exit(1);
}
break;
case 'c':
// inner FEC scheme
fec0 = liquid_getopt_str2fec(optarg);
if (fec0 == LIQUID_FEC_UNKNOWN) {
fprintf(stderr,"error: unknown/unsupported inner FEC scheme \"%s\"\n\n",optarg);
exit(1);
}
break;
case 'k':
// outer FEC scheme
fec1 = liquid_getopt_str2fec(optarg);
if (fec1 == LIQUID_FEC_UNKNOWN) {
fprintf(stderr,"error: unknown/unsupported outer FEC scheme \"%s\"\n\n",optarg);
exit(1);
}
break;
default:
exit(-1);
}
}
unsigned int i;
// TODO : validate options
// derived values
unsigned int frame_len = M + cp_len;
float complex buffer[frame_len]; // time-domain buffer
float nstd = powf(10.0f, noise_floor/20.0f);
float gamma = powf(10.0f, (SNRdB + noise_floor)/20.0f);
// allocate memory for header, payload
unsigned char header[8];
unsigned char payload[payload_len];
// initialize subcarrier allocation
unsigned char p[M];
ofdmframe_init_default_sctype(M, p);
// create frame generator
ofdmflexframegenprops_s fgprops;
ofdmflexframegenprops_init_default(&fgprops);
fgprops.check = check;
fgprops.fec0 = fec0;
fgprops.fec1 = fec1;
fgprops.mod_scheme = ms;
ofdmflexframegen fg = ofdmflexframegen_create(M, cp_len, taper_len, p, &fgprops);
// create frame synchronizer
ofdmflexframesync fs = ofdmflexframesync_create(M, cp_len, taper_len, p, callback, (void*)payload);
if (debug_enabled)
ofdmflexframesync_debug_enable(fs);
// initialize header/payload and assemble frame
for (i=0; i<8; i++)
header[i] = i & 0xff;
for (i=0; i<payload_len; i++)
payload[i] = rand() & 0xff;
ofdmflexframegen_assemble(fg, header, payload, payload_len);
ofdmflexframegen_print(fg);
ofdmflexframesync_print(fs);
// initialize frame synchronizer with noise
for (i=0; i<1000; i++) {
float complex noise = nstd*( randnf() + _Complex_I*randnf())*M_SQRT1_2;
ofdmflexframesync_execute(fs, &noise, 1);
}
// generate frame, push through channel
int last_symbol=0;
nco_crcf nco = nco_crcf_create(LIQUID_VCO);
nco_crcf_set_frequency(nco, dphi);
while (!last_symbol) {
// generate symbol
last_symbol = ofdmflexframegen_writesymbol(fg, buffer);
// apply channel
for (i=0; i<frame_len; i++) {
float complex noise = nstd*( randnf() + _Complex_I*randnf())*M_SQRT1_2;
buffer[i] *= gamma;
buffer[i] += noise;
nco_crcf_mix_up(nco, buffer[i], &buffer[i]);
nco_crcf_step(nco);
}
// receive symbol
ofdmflexframesync_execute(fs, buffer, frame_len);
}
nco_crcf_destroy(nco);
// export debugging file
if (debug_enabled)
ofdmflexframesync_debug_print(fs, "ofdmflexframesync_debug.m");
// destroy objects
ofdmflexframegen_destroy(fg);
ofdmflexframesync_destroy(fs);
printf("done.\n");
return 0;
}
int main(int argc, char*argv[])
{
srand(time(NULL));
// options
unsigned int num_symbols=500; // number of symbols to observe
float SNRdB = 30.0f; // signal-to-noise ratio [dB]
unsigned int hc_len=5; // channel filter length
unsigned int k=2; // matched filter samples/symbol
unsigned int m=3; // matched filter delay (symbols)
float beta=0.3f; // matched filter excess bandwidth factor
unsigned int p=3; // equalizer length (symbols, hp_len = 2*k*p+1)
float mu = 0.08f; // learning rate
// modulation type/depth
modulation_scheme ms = LIQUID_MODEM_QPSK;
int dopt;
while ((dopt = getopt(argc,argv,"hn:s:c:k:m:b:p:u:M:")) != EOF) {
switch (dopt) {
case 'h': usage(); return 0;
case 'n': num_symbols = atoi(optarg); break;
case 's': SNRdB = atof(optarg); break;
case 'c': hc_len = atoi(optarg); break;
case 'k': k = atoi(optarg); break;
case 'm': m = atoi(optarg); break;
case 'b': beta = atof(optarg); break;
case 'p': p = atoi(optarg); break;
case 'u': mu = atof(optarg); break;
case 'M':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported modulation scheme '%s'\n", argv[0], optarg);
return 1;
}
break;
default:
exit(1);
}
}
// validate input
if (num_symbols == 0) {
fprintf(stderr,"error: %s, number of symbols must be greater than zero\n", argv[0]);
exit(1);
} else if (hc_len == 0) {
fprintf(stderr,"error: %s, channel must have at least 1 tap\n", argv[0]);
exit(1);
} else if (k < 2) {
fprintf(stderr,"error: %s, samples/symbol must be at least 2\n", argv[0]);
exit(1);
} else if (m == 0) {
fprintf(stderr,"error: %s, filter semi-length must be at least 1 symbol\n", argv[0]);
exit(1);
} else if (beta < 0.0f || beta > 1.0f) {
fprintf(stderr,"error: %s, filter excess bandwidth must be in [0,1]\n", argv[0]);
exit(1);
} else if (p == 0) {
fprintf(stderr,"error: %s, equalizer semi-length must be at least 1 symbol\n", argv[0]);
exit(1);
} else if (mu < 0.0f || mu > 1.0f) {
fprintf(stderr,"error: %s, equalizer learning rate must be in [0,1]\n", argv[0]);
exit(1);
}
// derived values
unsigned int hm_len = 2*k*m+1; // matched filter length
unsigned int hp_len = 2*k*p+1; // equalizer filter length
unsigned int num_samples = k*num_symbols;
// bookkeeping variables
float complex sym_tx[num_symbols]; // transmitted data sequence
float complex x[num_samples]; // interpolated time series
float complex y[num_samples]; // channel output
float complex z[num_samples]; // equalized output
float hm[hm_len]; // matched filter response
float complex hc[hc_len]; // channel filter coefficients
float complex hp[hp_len]; // equalizer filter coefficients
unsigned int i;
// generate matched filter response
liquid_firdes_rnyquist(LIQUID_FIRFILT_RRC, k, m, beta, 0.0f, hm);
firinterp_crcf interp = firinterp_crcf_create(k, hm, hm_len);
// create the modem objects
modem mod = modem_create(ms);
modem demod = modem_create(ms);
unsigned int M = 1 << modem_get_bps(mod);
// generate channel impulse response, filter
hc[0] = 1.0f;
for (i=1; i<hc_len; i++)
hc[i] = 0.09f*(randnf() + randnf()*_Complex_I);
firfilt_cccf fchannel = firfilt_cccf_create(hc, hc_len);
// generate random symbols
for (i=0; i<num_symbols; i++)
modem_modulate(mod, rand()%M, &sym_tx[i]);
// interpolate
for (i=0; i<num_symbols; i++)
firinterp_crcf_execute(interp, sym_tx[i], &x[i*k]);
// push through channel
float nstd = powf(10.0f, -SNRdB/20.0f);
for (i=0; i<num_samples; i++) {
firfilt_cccf_push(fchannel, x[i]);
firfilt_cccf_execute(fchannel, &y[i]);
// add noise
y[i] += nstd*(randnf() + randnf()*_Complex_I)*M_SQRT1_2;
}
// push through equalizer
// create equalizer, intialized with square-root Nyquist filter
eqlms_cccf eq = eqlms_cccf_create_rnyquist(LIQUID_FIRFILT_RRC, k, p, beta, 0.0f);
eqlms_cccf_set_bw(eq, mu);
// get initialized weights
eqlms_cccf_get_weights(eq, hp);
// filtered error vector magnitude (emperical RMS error)
float evm_hat = 0.03f;
float complex d_hat = 0.0f;
for (i=0; i<num_samples; i++) {
// print filtered evm (emperical rms error)
if ( ((i+1)%50)==0 )
printf("%4u : rms error = %12.8f dB\n", i+1, 10*log10(evm_hat));
eqlms_cccf_push(eq, y[i]);
eqlms_cccf_execute(eq, &d_hat);
// store output
z[i] = d_hat;
// decimate by k
if ( (i%k) != 0 ) continue;
// estimate transmitted signal
unsigned int sym_out; // output symbol
float complex d_prime; // estimated input sample
modem_demodulate(demod, d_hat, &sym_out);
modem_get_demodulator_sample(demod, &d_prime);
// update equalizer
eqlms_cccf_step(eq, d_prime, d_hat);
// update filtered evm estimate
float evm = crealf( (d_prime-d_hat)*conjf(d_prime-d_hat) );
evm_hat = 0.98f*evm_hat + 0.02f*evm;
}
// get equalizer weights
eqlms_cccf_get_weights(eq, hp);
// destroy objects
eqlms_cccf_destroy(eq);
firinterp_crcf_destroy(interp);
firfilt_cccf_destroy(fchannel);
modem_destroy(mod);
modem_destroy(demod);
//
// export output
//
FILE * fid = fopen(OUTPUT_FILENAME,"w");
fprintf(fid,"%% %s : auto-generated file\n\n", OUTPUT_FILENAME);
fprintf(fid,"clear all\n");
fprintf(fid,"close all\n");
fprintf(fid,"k = %u;\n", k);
fprintf(fid,"m = %u;\n", m);
fprintf(fid,"num_symbols = %u;\n", num_symbols);
fprintf(fid,"num_samples = num_symbols*k;\n");
// save transmit matched-filter response
fprintf(fid,"hm_len = 2*k*m+1;\n");
fprintf(fid,"hm = zeros(1,hm_len);\n");
for (i=0; i<hm_len; i++)
fprintf(fid,"hm(%4u) = %12.4e;\n", i+1, hm[i]);
// save channel impulse response
fprintf(fid,"hc_len = %u;\n", hc_len);
fprintf(fid,"hc = zeros(1,hc_len);\n");
for (i=0; i<hc_len; i++)
fprintf(fid,"hc(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(hc[i]), cimagf(hc[i]));
// save equalizer response
fprintf(fid,"hp_len = %u;\n", hp_len);
fprintf(fid,"hp = zeros(1,hp_len);\n");
for (i=0; i<hp_len; i++)
fprintf(fid,"hp(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(hp[i]), cimagf(hp[i]));
// save sample sets
fprintf(fid,"x = zeros(1,num_samples);\n");
fprintf(fid,"y = zeros(1,num_samples);\n");
fprintf(fid,"z = zeros(1,num_samples);\n");
for (i=0; i<num_samples; i++) {
fprintf(fid,"x(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(x[i]), cimagf(x[i]));
fprintf(fid,"y(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(y[i]), cimagf(y[i]));
fprintf(fid,"z(%4u) = %12.4e + j*%12.4e;\n", i+1, crealf(z[i]), cimagf(z[i]));
}
// plot time response
fprintf(fid,"t = 0:(num_samples-1);\n");
fprintf(fid,"tsym = 1:k:num_samples;\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(t,real(z),...\n");
fprintf(fid," t(tsym),real(z(tsym)),'x');\n");
// plot constellation
fprintf(fid,"tsym0 = tsym(1:(length(tsym)/2));\n");
fprintf(fid,"tsym1 = tsym((length(tsym)/2):end);\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(real(z(tsym0)),imag(z(tsym0)),'x','Color',[1 1 1]*0.7,...\n");
fprintf(fid," real(z(tsym1)),imag(z(tsym1)),'x','Color',[1 1 1]*0.0);\n");
fprintf(fid,"xlabel('In-Phase');\n");
fprintf(fid,"ylabel('Quadrature');\n");
fprintf(fid,"axis([-1 1 -1 1]*1.5);\n");
fprintf(fid,"axis square;\n");
fprintf(fid,"grid on;\n");
// compute composite response
fprintf(fid,"g = real(conv(conv(hm,hc),hp));\n");
// plot responses
fprintf(fid,"nfft = 1024;\n");
fprintf(fid,"f = [0:(nfft-1)]/nfft - 0.5;\n");
fprintf(fid,"Hm = 20*log10(abs(fftshift(fft(hm/k,nfft))));\n");
fprintf(fid,"Hc = 20*log10(abs(fftshift(fft(hc, nfft))));\n");
fprintf(fid,"Hp = 20*log10(abs(fftshift(fft(hp, nfft))));\n");
fprintf(fid,"G = 20*log10(abs(fftshift(fft(g/k, nfft))));\n");
fprintf(fid,"figure;\n");
fprintf(fid,"plot(f,Hm, f,Hc, f,Hp, f,G,'-k','LineWidth',2, [-0.5/k 0.5/k],[-6.026 -6.026],'or');\n");
fprintf(fid,"xlabel('Normalized Frequency');\n");
fprintf(fid,"ylabel('Power Spectral Density');\n");
fprintf(fid,"legend('transmit','channel','equalizer','composite','half-power points',1);\n");
fprintf(fid,"axis([-0.5 0.5 -12 8]);\n");
fprintf(fid,"grid on;\n");
fclose(fid);
printf("results written to '%s'\n", OUTPUT_FILENAME);
return 0;
}
int main(int argc, char *argv[]) {
srand( time(NULL) );
// define parameters
float SNRdB_start = -5.0f;
float SNRdB_step = 1.0f;
float SNRdB_max = 10.0f;
unsigned int num_frames = 1000;
//float noise_floor = -30.0f;
const char * filename = "ofdmflexframe_fer_results.dat";
modulation_scheme ms = LIQUID_MODEM_QPSK;
unsigned int M = 64;
unsigned int cp_len = 16;
unsigned int payload_len= 256;
crc_scheme check = LIQUID_CRC_32;
fec_scheme fec0 = LIQUID_FEC_HAMMING128;
fec_scheme fec1 = LIQUID_FEC_NONE;
int verbose = 1;
// get command-line options
int dopt;
while((dopt = getopt(argc,argv,"uho:s:d:x:n:f:M:C:m:c:k:")) != EOF){
switch (dopt) {
case 'h':
case 'u': usage(); return 0;
case 'o': filename = optarg; break;
case 's': SNRdB_start = atof(optarg); break;
case 'd': SNRdB_step = atof(optarg); break;
case 'x': SNRdB_max = atof(optarg); break;
case 'n': num_frames = atol(optarg); break;
case 'f': payload_len = atol(optarg); break;
case 'M': M = atoi(optarg); break;
case 'C': cp_len = atoi(optarg); break;
case 'm':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
printf("error: unknown/unsupported mod. scheme: %s\n", optarg);
exit(1);
}
break;
case 'c':
fec0 = liquid_getopt_str2fec(optarg);
if (fec0 == LIQUID_FEC_UNKNOWN) {
printf("error: unknown/unsupported fec scheme \"%s\"\n", optarg);
exit(1);
}
break;
case 'k':
fec1 = liquid_getopt_str2fec(optarg);
if (fec1 == LIQUID_FEC_UNKNOWN) {
printf("error: unknown/unsupported fec scheme \"%s\"\n", optarg);
exit(1);
}
break;
default:
fprintf(stderr,"error: %s, unknown option\n", argv[0]);
exit(1);
}
}
// validate options
if (SNRdB_step <= 0.0f) {
printf("error: SNRdB_step must be greater than zero\n");
exit(-1);
} else if (SNRdB_max < SNRdB_start) {
printf("error: SNRdB_max must be greater than SNRdB_start\n");
exit(-1);
}
// set up framing simulation options
ofdmflexframe_fer_opts opts;
opts.M = M;
opts.cp_len = cp_len;
opts.p = NULL;
opts.ms = ms;
opts.check = check;
opts.fec0 = fec0;
opts.fec1 = fec1;
opts.payload_len= payload_len;
opts.num_frames = num_frames;
opts.verbose = verbose;
// create results objects
fer_results results;
// bookkeeping variables
unsigned int i;
float SNRdB = SNRdB_start;
// open output file
FILE * fid = fopen(filename,"w");
if (!fid) {
fprintf(stderr,"error: could not open '%s' for writing\n", filename);
exit(1);
}
fprintf(fid,"# %s : auto-generated file\n", filename);
fprintf(fid,"# invoked as: ");
for (i=0; i<argc; i++) fprintf(fid,"%s ", argv[i]);
fprintf(fid,"\n");
fprintf(fid,"#\n");
fprintf(fid,"# M (subcarriers) : %u\n", opts.M);
fprintf(fid,"# cyclic prefix : %u\n", opts.cp_len);
fprintf(fid,"# allocation : \n"); // ofdmframe_print_sctype(opts.p, opts.M);
fprintf(fid,"# modulation scheme : %s\n", modulation_types[opts.ms].fullname);
fprintf(fid,"# modulation depth : %u bits/symbol\n", modulation_types[opts.ms].bps);
fprintf(fid,"# check : %s\n", crc_scheme_str[opts.check][1]);
fprintf(fid,"# fec (inner) : %s\n", fec_scheme_str[opts.fec0][1]);
fprintf(fid,"# fec (outer) : %s\n", fec_scheme_str[opts.fec1][1]);
fprintf(fid,"# payload length : %u bytes\n", opts.payload_len);
fprintf(fid,"# frame trials : %u\n", opts.num_frames);
fprintf(fid,"#\n");
fprintf(fid,"# %8s %12s %12s %12s %12s %12s %12s %12s\n",
"SNR [dB]",
"FER (frame)",
"HER (header)",
"PER (packet)",
"frames",
"headers",
"packets",
"num trials");
fclose(fid);
// start running batch trials
while (SNRdB <= SNRdB_max) {
// run trials
ofdmflexframe_fer(opts, SNRdB, &results);
// append results to file
fid = fopen(filename,"a");
fprintf(fid," %8.2f %12.10f %12.10f %12.10f %12u %12u %12u %12u\n",
SNRdB,
results.FER,
results.HER,
results.PER,
results.num_missed_frames,
results.num_header_errors,
results.num_packet_errors,
results.num_frames);
fclose(fid);
SNRdB += SNRdB_step;
}
printf("results written to '%s'\n", filename);
return 0;
}
int main(int argc, char*argv[])
{
// options
unsigned int num_symbols=500; // number of symbols to observe
float SNRdB = 30.0f; // signal-to-noise ratio [dB]
unsigned int hc_len=5; // channel filter length
unsigned int k=2; // matched filter samples/symbol
unsigned int m=3; // matched filter delay (symbols)
float beta=0.3f; // matched filter excess bandwidth factor
unsigned int p=3; // equalizer length (symbols, gr_len = 2*k*p+1)
float mu = 0.09f; // LMS learning rate
// modulation type/depth
modulation_scheme ms = LIQUID_MODEM_QPSK;
// plotting options
unsigned int nfft = 512; // fft size
float gnuplot_version = 4.2;
char filename_base[256] = "figures.gen/eqlms_cccf_blind";
int dopt;
while ((dopt = getopt(argc,argv,"hf:g:n:s:c:k:m:b:p:u:M:")) != EOF) {
switch (dopt) {
case 'h': usage(); return 0;
case 'f': strncpy(filename_base,optarg,256); break;
case 'g': gnuplot_version = atoi(optarg); break;
case 'n': num_symbols = atoi(optarg); break;
case 's': SNRdB = atof(optarg); break;
case 'c': hc_len = atoi(optarg); break;
case 'k': k = atoi(optarg); break;
case 'm': m = atoi(optarg); break;
case 'b': beta = atof(optarg); break;
case 'p': p = atoi(optarg); break;
case 'u': mu = atof(optarg); break;
case 'M':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported modulation scheme '%s'\n", argv[0], optarg);
return 1;
}
break;
default:
exit(1);
}
}
// validate input
if (num_symbols == 0) {
fprintf(stderr,"error: %s, number of symbols must be greater than zero\n", argv[0]);
exit(1);
} else if (hc_len == 0) {
fprintf(stderr,"error: %s, channel must have at least 1 tap\n", argv[0]);
exit(1);
} else if (k < 2) {
fprintf(stderr,"error: %s, samples/symbol must be at least 2\n", argv[0]);
exit(1);
} else if (m == 0) {
fprintf(stderr,"error: %s, filter semi-length must be at least 1 symbol\n", argv[0]);
exit(1);
} else if (beta < 0.0f || beta > 1.0f) {
fprintf(stderr,"error: %s, filter excess bandwidth must be in [0,1]\n", argv[0]);
exit(1);
} else if (p == 0) {
fprintf(stderr,"error: %s, equalizer semi-length must be at least 1 symbol\n", argv[0]);
exit(1);
} else if (mu < 0.0f || mu > 1.0f) {
fprintf(stderr,"error: %s, equalizer learning rate must be in [0,1]\n", argv[0]);
exit(1);
}
// set 'random' seed on options
srand( hc_len + p + nfft );
// derived values
unsigned int gt_len = 2*k*m+1; // matched filter length
unsigned int gr_len = 2*k*p+1; // equalizer filter length
unsigned int num_samples = k*num_symbols;
// bookkeeping variables
float complex sym_tx[num_symbols]; // transmitted data sequence
float complex x[num_samples]; // interpolated time series
float complex y[num_samples]; // channel output
float complex z[num_samples]; // equalized output
// least mean-squares (LMS) equalizer
float mse[num_symbols]; // equalizer mean-squared error
float complex gr[gr_len]; // equalizer filter coefficients
unsigned int i;
// generate matched filter response
float gtf[gt_len]; // matched filter response
liquid_firdes_rnyquist(LIQUID_RNYQUIST_RRC, k, m, beta, 0.0f, gtf);
// convert to complex coefficients
float complex gt[gt_len];
for (i=0; i<gt_len; i++)
gt[i] = gtf[i]; //+ 0.1f*(randnf() + _Complex_I*randnf());
// create interpolator
interp_cccf interp = interp_cccf_create(k, gt, gt_len);
// create the modem objects
modem mod = modem_create(ms);
modem demod = modem_create(ms);
unsigned int bps = modem_get_bps(mod);
unsigned int M = 1 << bps;
// generate channel impulse response, filter
#if 0
float complex hc[hc_len]; // channel filter coefficients
hc[0] = 1.0f;
for (i=1; i<hc_len; i++)
hc[i] = 0.09f*(randnf() + randnf()*_Complex_I);
#else
// use fixed channel
hc_len = 8;
float complex hc[hc_len]; // channel filter coefficients
hc[0] = 1.00000000+ 0.00000000*_Complex_I;
hc[1] = 0.08077553+ -0.00247592*_Complex_I;
hc[2] = 0.03625883+ -0.09219734*_Complex_I;
hc[3] = 0.05764082+ 0.03277601*_Complex_I;
hc[4] = -0.04773349+ -0.18766306*_Complex_I;
hc[5] = -0.00101735+ -0.00270737*_Complex_I;
hc[6] = -0.05796884+ -0.12665297*_Complex_I;
hc[7] = 0.03805391+ -0.07609370*_Complex_I;
#endif
firfilt_cccf fchannel = firfilt_cccf_create(hc, hc_len);
firfilt_cccf_print(fchannel);
// generate random symbols
for (i=0; i<num_symbols; i++)
modem_modulate(mod, rand()%M, &sym_tx[i]);
// interpolate
for (i=0; i<num_symbols; i++)
interp_cccf_execute(interp, sym_tx[i], &x[i*k]);
// push through channel
float nstd = powf(10.0f, -SNRdB/20.0f);
for (i=0; i<num_samples; i++) {
firfilt_cccf_push(fchannel, x[i]);
firfilt_cccf_execute(fchannel, &y[i]);
// add noise
y[i] += nstd*(randnf() + randnf()*_Complex_I)*M_SQRT1_2;
}
// push through equalizers
float grf[gr_len];
liquid_firdes_rnyquist(LIQUID_RNYQUIST_RRC, k, p, beta, 0.0f, grf);
for (i=0; i<gr_len; i++) {
gr[i] = grf[i] / (float)k;
}
// create LMS equalizer
eqlms_cccf eq = eqlms_cccf_create(gr, gr_len);
eqlms_cccf_set_bw(eq, mu);
// filtered error vector magnitude (emperical MSE)
//float zeta=0.05f; // smoothing factor (small zeta -> smooth MSE)
float complex d_hat = 0.0f;
unsigned int num_symbols_rx=0;
for (i=0; i<num_samples; i++) {
// push samples into equalizers
eqlms_cccf_push(eq, y[i]);
// compute outputs
eqlms_cccf_execute(eq, &d_hat);
// store outputs
z[i] = d_hat;
// check to see if buffer is full
if ( i < gr_len) continue;
// decimate by k
if ( (i%k) != 0 ) continue;
// estimate transmitted signal
unsigned int sym_out; // output symbol
float complex d_prime; // estimated input sample
// LMS
modem_demodulate(demod, d_hat, &sym_out);
modem_get_demodulator_sample(demod, &d_prime);
// update equalizers
eqlms_cccf_step(eq, d_prime, d_hat);
#if 0
// update filtered evm estimate
float evm = crealf( (d_prime-d_hat)*conjf(d_prime-d_hat) );
if (num_symbols_rx == 0) {
mse[num_symbols_rx] = evm;
} else {
mse[num_symbols_rx] = mse[num_symbols_rx-1]*(1-zeta) + evm*zeta;
}
#else
// compute ISI for entire system
eqlms_cccf_get_weights(eq, gr);
mse[num_symbols_rx] = eqlms_cccf_isi(k, gt, gt_len, hc, hc_len, gr, gr_len);
#endif
// print filtered evm (emperical rms error)
if ( ((num_symbols_rx+1)%100) == 0 )
printf("%4u : mse = %12.8f dB\n",
num_symbols_rx+1,
20*log10f(mse[num_symbols_rx]));
// increment output symbol counter
num_symbols_rx++;
}
// get equalizer weights
eqlms_cccf_get_weights(eq, gr);
// destroy objects
eqlms_cccf_destroy(eq);
interp_cccf_destroy(interp);
firfilt_cccf_destroy(fchannel);
modem_destroy(mod);
modem_destroy(demod);
//
// export output
//
FILE * fid = NULL;
char filename[300];
//
// const: constellation
//
strncpy(filename, filename_base, 256);
strcat(filename, "_const.gnu");
fid = fopen(filename,"w");
if (!fid) {
fprintf(stderr,"error: %s, could not open file '%s' for writing\n", argv[0], filename);
return 1;
}
fprintf(fid,"# %s: auto-generated file\n\n", filename);
fprintf(fid,"reset\n");
fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n");
fprintf(fid,"set size ratio 1\n");
fprintf(fid,"set xrange [-1.5:1.5];\n");
fprintf(fid,"set yrange [-1.5:1.5];\n");
fprintf(fid,"set xlabel 'In-phase'\n");
fprintf(fid,"set ylabel 'Quadrature phase'\n");
fprintf(fid,"set grid xtics ytics\n");
fprintf(fid,"set grid linetype 1 linecolor rgb '%s' linewidth 1\n",LIQUID_DOC_COLOR_GRID);
fprintf(fid,"plot '-' using 1:2 with points pointtype 7 pointsize 0.5 linecolor rgb '%s' title 'first 50%%',\\\n", LIQUID_DOC_COLOR_GRAY);
fprintf(fid," '-' using 1:2 with points pointtype 7 pointsize 0.7 linecolor rgb '%s' title 'last 50%%'\n", LIQUID_DOC_COLOR_RED);
// first half of symbols
for (i=2*p; i<num_symbols/2; i+=k)
fprintf(fid," %12.4e %12.4e\n", crealf(y[i]), cimagf(y[i]));
fprintf(fid,"e\n");
// second half of symbols
for ( ; i<num_symbols; i+=k)
fprintf(fid," %12.4e %12.4e\n", crealf(z[i]), cimagf(z[i]));
fprintf(fid,"e\n");
fclose(fid);
printf("results written to '%s'\n", filename);
//
// mse : mean-squared error
//
strncpy(filename, filename_base, 256);
strcat(filename, "_mse.gnu");
fid = fopen(filename,"w");
if (!fid) {
fprintf(stderr,"error: %s, could not open file '%s' for writing\n", argv[0], filename);
return 1;
}
fprintf(fid,"# %s: auto-generated file\n\n", filename);
fprintf(fid,"reset\n");
fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n");
fprintf(fid,"set size ratio 0.3\n");
fprintf(fid,"set xrange [0:%u];\n", num_symbols);
fprintf(fid,"set yrange [1e-3:1e-1];\n");
fprintf(fid,"set format y '10^{%%L}'\n");
fprintf(fid,"set log y\n");
fprintf(fid,"set xlabel 'symbol index'\n");
fprintf(fid,"set ylabel 'mean-squared error'\n");
fprintf(fid,"set grid xtics ytics\n");
fprintf(fid,"set grid linetype 1 linecolor rgb '%s' linewidth 1\n",LIQUID_DOC_COLOR_GRID);
fprintf(fid,"plot '-' using 1:2 with lines linewidth 4 linetype 1 linecolor rgb '%s' title 'LMS MSE'\n", LIQUID_DOC_COLOR_RED);
// LMS
for (i=0; i<num_symbols_rx; i++)
fprintf(fid," %4u %16.8e\n", i, mse[i]);
fprintf(fid,"e\n");
fclose(fid);
printf("results written to '%s'\n", filename);
//
// psd : power spectral density
//
// scale transmit filter appropriately
for (i=0; i<gt_len; i++) gt[i] /= (float)k;
float complex Gt[nfft]; // transmit matched filter
float complex Hc[nfft]; // channel response
float complex Gr[nfft]; // equalizer response
liquid_doc_compute_psdcf(gt, gt_len, Gt, nfft, LIQUID_DOC_PSDWINDOW_NONE, 0);
liquid_doc_compute_psdcf(hc, hc_len, Hc, nfft, LIQUID_DOC_PSDWINDOW_NONE, 0);
liquid_doc_compute_psdcf(gr, gr_len, Gr, nfft, LIQUID_DOC_PSDWINDOW_NONE, 0);
fft_shift(Gt, nfft);
fft_shift(Hc, nfft);
fft_shift(Gr, nfft);
float freq[nfft];
for (i=0; i<nfft; i++)
freq[i] = (float)(i) / (float)nfft - 0.5f;
strncpy(filename, filename_base, 256);
strcat(filename, "_freq.gnu");
fid = fopen(filename,"w");
if (!fid) {
fprintf(stderr,"error: %s, could not open file '%s' for writing\n", argv[0], filename);
return 1;
}
fprintf(fid,"# %s: auto-generated file\n\n", filename);
fprintf(fid,"reset\n");
fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n");
fprintf(fid,"set size ratio 0.6\n");
fprintf(fid,"set xrange [-0.5:0.5];\n");
fprintf(fid,"set yrange [-10:6]\n");
fprintf(fid,"set xlabel 'Normalized Frequency'\n");
fprintf(fid,"set ylabel 'Power Spectral Density [dB]'\n");
fprintf(fid,"set key top right nobox\n");
fprintf(fid,"set grid xtics ytics\n");
fprintf(fid,"set grid linetype 1 linecolor rgb '%s' lw 1\n",LIQUID_DOC_COLOR_GRID);
fprintf(fid,"plot '-' using 1:2 with lines linetype 1 linewidth 1.5 linecolor rgb '%s' title 'transmit',\\\n", LIQUID_DOC_COLOR_GRAY);
fprintf(fid," '-' using 1:2 with lines linetype 1 linewidth 1.5 linecolor rgb '%s' title 'channel',\\\n", LIQUID_DOC_COLOR_RED);
fprintf(fid," '-' using 1:2 with lines linetype 1 linewidth 1.5 linecolor rgb '%s' title 'equalizer',\\\n", LIQUID_DOC_COLOR_GREEN);
fprintf(fid," '-' using 1:2 with lines linetype 1 linewidth 4.0 linecolor rgb '%s' title 'composite',\\\n", LIQUID_DOC_COLOR_BLUE);
fprintf(fid," '-' using 1:2 with points pointtype 7 pointsize 0.6 linecolor rgb '%s' notitle\n", LIQUID_DOC_COLOR_BLUE);
// received signal
for (i=0; i<nfft; i++)
fprintf(fid,"%12.8f %12.4e\n", freq[i], 20*log10f(cabsf(Gt[i])) );
fprintf(fid,"e\n");
// channel
for (i=0; i<nfft; i++)
fprintf(fid,"%12.8f %12.4e\n", freq[i], 20*log10f(cabsf(Hc[i])) );
fprintf(fid,"e\n");
// equalizer
for (i=0; i<nfft; i++)
fprintf(fid,"%12.8f %12.4e\n", freq[i], 20*log10f(cabsf(Gr[i])) );
fprintf(fid,"e\n");
// composite
for (i=0; i<nfft; i++)
fprintf(fid,"%12.8f %12.4e\n", freq[i], 20*log10f( cabsf(Gt[i])*cabsf(Hc[i])*cabsf(Gr[i])) );
fprintf(fid,"e\n");
// composite
fprintf(fid,"%12.8f %12.4e\n", -0.5f/(float)k, 20*log10f(0.5f));
fprintf(fid,"%12.8f %12.4e\n", 0.5f/(float)k, 20*log10f(0.5f));
fprintf(fid,"e\n");
fclose(fid);
printf("results written to '%s'\n", filename);
//
// time...
//
strncpy(filename, filename_base, 256);
strcat(filename, "_time.gnu");
fid = fopen(filename,"w");
if (!fid) {
fprintf(stderr,"error: %s, could not open file '%s' for writing\n", argv[0], filename);
return 1;
}
fprintf(fid,"# %s: auto-generated file\n\n", filename);
fprintf(fid,"reset\n");
fprintf(fid,"set terminal postscript eps enhanced color solid rounded\n");
fprintf(fid,"set xrange [0:%u];\n",num_symbols);
fprintf(fid,"set yrange [-1.5:1.5]\n");
fprintf(fid,"set size ratio 0.3\n");
fprintf(fid,"set xlabel 'Symbol Index'\n");
fprintf(fid,"set key top right nobox\n");
//fprintf(fid,"set ytics -5,1,5\n");
fprintf(fid,"set grid xtics ytics\n");
fprintf(fid,"set pointsize 0.6\n");
fprintf(fid,"set grid linetype 1 linecolor rgb '%s' lw 1\n", LIQUID_DOC_COLOR_GRID);
fprintf(fid,"set multiplot layout 2,1 scale 1.0,1.0\n");
// real
fprintf(fid,"# real\n");
fprintf(fid,"set ylabel 'Real'\n");
fprintf(fid,"plot '-' using 1:2 with lines linetype 1 linewidth 1 linecolor rgb '#999999' notitle,\\\n");
fprintf(fid," '-' using 1:2 with points pointtype 7 linecolor rgb '%s' notitle'\n", LIQUID_DOC_COLOR_BLUE);
//
for (i=0; i<num_samples; i++)
fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k, crealf(z[i]));
fprintf(fid,"e\n");
//
for (i=0; i<num_samples; i+=k)
fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k, crealf(z[i]));
fprintf(fid,"e\n");
// imag
fprintf(fid,"# imag\n");
fprintf(fid,"set ylabel 'Imag'\n");
fprintf(fid,"plot '-' using 1:2 with lines linetype 1 linewidth 1 linecolor rgb '#999999' notitle,\\\n");
fprintf(fid," '-' using 1:2 with points pointtype 7 linecolor rgb '%s' notitle'\n", LIQUID_DOC_COLOR_GREEN);
//
for (i=0; i<num_samples; i++)
fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k, cimagf(z[i]));
fprintf(fid,"e\n");
//
for (i=0; i<num_samples; i+=k)
fprintf(fid,"%12.8f %12.4e\n", (float)i/(float)k, cimagf(z[i]));
fprintf(fid,"e\n");
fprintf(fid,"unset multiplot\n");
// close output file
fclose(fid);
printf("results written to '%s'\n", filename);
return 0;
}
int main(int argc, char*argv[]) {
srand( time(NULL) );
// options
int verbose = 1; // verbose output flag
float phi_max_abs = M_PI/4.0f; // absolute maximum phase offset
unsigned int num_phi = 21; // number of phase steps
unsigned int num_trials = 1000; // number of trials
float SNRdB = 12.0f; // signal-to-noise ratio [dB]
modulation_scheme ms = LIQUID_MODEM_QPSK;
char filename[256] = ""; // output filename
int dopt;
while ((dopt = getopt(argc,argv,"uhvqn:t:s:P:m:o:")) != EOF) {
switch (dopt) {
case 'u':
case 'h': usage(); return 0;
case 'v': verbose = 1; break;
case 'q': verbose = 0; break;
case 'n': num_phi = atoi(optarg); break;
case 't': num_trials = atoi(optarg); break;
case 's': SNRdB = atof(optarg); break;
case 'P': phi_max_abs = atof(optarg); break;
case 'm':
ms = liquid_getopt_str2mod(optarg);
if (ms == LIQUID_MODEM_UNKNOWN) {
fprintf(stderr,"error: %s, unknown/unsupported modulation scheme \"%s\"\n", argv[0], optarg);
return 1;
}
break;
case 'o': strncpy(filename,optarg,255); break;
default:
exit(1);
}
}
// validate input
if (phi_max_abs <= 0.0f) {
fprintf(stderr,"error: %s, maximum absolute phase offset must be greater than 0\n", argv[0]);
exit(1);
} else if (num_phi < 3) {
fprintf(stderr,"error: %s, number of phase steps must be at least 3\n", argv[0]);
exit(1);
fprintf(stderr,"error: %s, number of trials must be greater than 0\n", argv[0]);
exit(1);
}
unsigned int bps = modulation_types[ms].bps;
// generate filenames
if ( strcmp(filename,"")==0 )
sprintf(filename,"figures.gen/modem_phase_error_%s%u.dat", modulation_types[ms].name, 1<<bps);
// derived values
float phi_min = 0.0f; //phi_max_abs;
float phi_max = phi_max_abs;
float phi_step = (phi_max - phi_min) / (float)(num_phi-1);
float nstd = powf(10.0f, -SNRdB/20.0f);
// arrays
float phi_hat_mean[num_phi]; // phase error estimate
float phi_hat_mean_smooth[num_phi]; // phase error estimate (smoothed)
// create modulator/demodulator
modem mod = modem_create(ms);
modem demod = modem_create(ms);
unsigned int M = 1 << bps;
//
unsigned int i;
unsigned int sym_in;
unsigned int sym_out;
unsigned int n=0; // trials counter
float complex x;
float phi_hat;
float phi=0.0f;
for (i=0; i<num_phi; i++) {
phi = phi_min + i*phi_step;
phi_hat_mean[i] = 0.0f;
// reset number of trials
n = 0;
do {
for (sym_in=0; sym_in<M; sym_in++) {
// modulate
modem_modulate(mod, sym_in, &x);
// channel (phase offset)
x *= cexpf(_Complex_I*phi);
x += nstd * (randnf() + _Complex_I*randnf()) * M_SQRT1_2;
// demodulate
modem_demodulate(demod, x, &sym_out);
// get error
phi_hat = modem_get_demodulator_phase_error(demod);
// accumulate average
phi_hat_mean[i] += phi_hat;
}
n += M;
} while (n < num_trials);
// scale by bps^2
//phi_hat_mean[i] *= bps*bps;
// normalize mean by number of trials
phi_hat_mean[i] /= (float) (n);
// print results
if (verbose)
printf("%6u / %6u : phi=%12.8f, phi-hat=%12.8f\n",
i+1, num_phi, phi, phi_hat_mean[i]);
}
// compute smoothed curve
float phi_hat_tmp[num_phi];
memmove(phi_hat_mean_smooth, phi_hat_mean, num_phi*sizeof(float));
unsigned int j;
for (j=0; j<5; j++) {
memmove(phi_hat_tmp, phi_hat_mean_smooth, num_phi*sizeof(float));
for (i=0; i<num_phi; i++) {
if (i==0 || i == num_phi-1) {
phi_hat_mean_smooth[i] = phi_hat_tmp[i];
} else {
phi_hat_mean_smooth[i] = 0.20f*phi_hat_tmp[i-1] +
0.60f*phi_hat_tmp[i ] +
0.20f*phi_hat_tmp[i+1];
}
}
}
// destroy objects
modem_destroy(mod);
modem_destroy(demod);
//
// export output file
//
FILE * fid = fopen(filename,"w");
if (!fid) {
fprintf(stderr,"error: %s, cannot open '%s' for writing\n", argv[0], filename);
exit(1);
}
fprintf(fid, "# %s : auto-generated file\n", filename);
fprintf(fid, "# \n");
// low SNR
fprintf(fid, "# %12s %12s %12s\n", "phi", "phi-hat", "phi-hat-smooth");
for (i=0; i<num_phi; i++) {
phi = phi_min + i*phi_step;
fprintf(fid," %12.8f %12.8f %12.8f\n", phi, phi_hat_mean[i], phi_hat_mean_smooth[i]);
}
fclose(fid);
if (verbose)
printf("results written to '%s'\n", filename);
return 0;
}