void LiquidOfdmModComponent::process() { DataSet< uint8_t >* in = NULL; getInputDataSet("input1", in); unsigned int payloadSize = (unsigned int)in->data.size(); unsigned char* payload = &in->data[0]; unsigned char header[8]; for (int i = 0; i < 8; i++) header[i] = frameHeader_x.c_str()[i] & 0xff; ofdmflexframegen_assemble(frameGenerator_, header, payload, payloadSize); unsigned int symbols = ofdmflexframegen_getframelen(frameGenerator_); unsigned int symbolSize = noSubcarriers_x + cyclicPrefixLength_x; unsigned int frameSize = symbols * symbolSize; if (debug_x) ofdmflexframegen_print(frameGenerator_); //Allocate memory for single symbol and whole frame DataSet< complex<float> >* out = NULL; getOutputDataSet("output1", out, frameSize); std::complex<float> buffer[symbolSize]; // generate frame, one OFDM symbol at a time unsigned int bytesWritten = 0; while (symbols--) { ofdmflexframegen_writesymbol(frameGenerator_, buffer); std::transform(buffer, buffer + symbolSize, out->data.begin() + bytesWritten, _1 * gain_factor_); bytesWritten += symbolSize; } out->timeStamp = in->timeStamp; // copy meta data of the frame releaseInputDataSet("input1", in); releaseOutputDataSet("output1", out); }
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; }