// Help function to keep code base small void modem_test_demodsoft(modulation_scheme _ms) { // generate mod/demod modem mod = modem_create(_ms); modem demod = modem_create(_ms); // unsigned int bps = modem_get_bps(demod); // run the test unsigned int i, s, M=1<<bps; unsigned int sym_soft; unsigned char soft_bits[bps]; float complex x; for (i=0; i<M; i++) { // modulate symbol modem_modulate(mod, i, &x); // demodulate using soft-decision modem_demodulate_soft(demod, x, &s, soft_bits); // check hard-decision output CONTEND_EQUALITY(s, i); // check soft bits liquid_pack_soft_bits(soft_bits, bps, &sym_soft); CONTEND_EQUALITY(sym_soft, i); // check phase error, evm, etc. //CONTEND_DELTA( modem_get_demodulator_phase_error(demod), 0.0f, 1e-3f); //CONTEND_DELTA( modem_get_demodulator_evm(demod), 0.0f, 1e-3f); } // clean it up modem_destroy(mod); modem_destroy(demod); }
// Helper function to keep code base small void modem_test_demodstats(modulation_scheme _ms) { // generate mod/demod modem mod = modem_create(_ms); modem demod = modem_create(_ms); // run the test unsigned int i, s, M = 1 << modem_get_bps(mod); float complex x; float complex x_hat; // rotated symbol float demodstats; float phi = 0.01f; for (i=0; i<M; i++) { // reset modem objects modem_reset(mod); modem_reset(demod); // modulate symbol modem_modulate(mod, i, &x); // ignore rare condition where modulated symbol is (0,0) // (e.g. APSK-8) if (cabsf(x) < 1e-3f) continue; // add phase offsets x_hat = x * cexpf( phi*_Complex_I); // demod positive phase signal, and ensure demodulator // maps to appropriate symbol modem_demodulate(demod, x_hat, &s); if (s != i) AUTOTEST_WARN("modem_test_demodstats(), output symbol does not match"); demodstats = modem_get_demodulator_phase_error(demod); CONTEND_EXPRESSION(demodstats > 0.0f); } // repeat with negative phase error for (i=0; i<M; i++) { // reset modem objects modem_reset(mod); modem_reset(demod); // modulate symbol modem_modulate(mod, i, &x); // ignore rare condition where modulated symbol is (0,0) // (e.g. APSK-8) if (cabsf(x) < 1e-3f) continue; // add phase offsets x_hat = x * cexpf(-phi*_Complex_I); // demod positive phase signal, and ensure demodulator // maps to appropriate symbol modem_demodulate(demod, x_hat, &s); if (s != i) AUTOTEST_WARN("modem_test_demodstats(), output symbol does not match"); demodstats = modem_get_demodulator_phase_error(demod); CONTEND_EXPRESSION(demodstats < 0.0f); } // clean up allocated objects up modem_destroy(mod); modem_destroy(demod); }
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 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) ); // 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 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[]) { // 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; }