/** Finds the PSS sequence previously defined by a call to sync_set_N_id_2() * around the position find_offset in the buffer input. * Returns 1 if the correlation peak exceeds the threshold set by sync_set_threshold() * or 0 otherwise. Returns a negative number on error (if N_id_2 has not been set) * * The maximum of the correlation peak is always stored in *peak_position */ int sync_find(sync_t *q, cf_t *input, uint32_t find_offset, uint32_t *peak_position) { int ret = LIBLTE_ERROR_INVALID_INPUTS; if (q != NULL && input != NULL && lte_N_id_2_isvalid(q->N_id_2) && fft_size_isvalid(q->fft_size)) { int peak_pos; ret = LIBLTE_SUCCESS; if (peak_position) { *peak_position = 0; } pss_synch_set_N_id_2(&q->pss, q->N_id_2); peak_pos = pss_synch_find_pss(&q->pss, &input[find_offset], &q->peak_value); if (peak_pos < 0) { fprintf(stderr, "Error calling finding PSS sequence\n"); return LIBLTE_ERROR; } q->mean_peak_value = VEC_EMA(q->peak_value, q->mean_peak_value, MEANPEAK_EMA_ALPHA); if (peak_position) { *peak_position = (uint32_t) peak_pos; } /* If peak is over threshold, compute CFO and SSS */ if (q->peak_value >= q->threshold) { // Make sure we have enough space to estimate CFO if (peak_pos + find_offset >= q->fft_size) { float cfo = pss_synch_cfo_compute(&q->pss, &input[find_offset+peak_pos-q->fft_size]); /* compute cumulative moving average CFO */ q->mean_cfo = VEC_EMA(cfo, q->mean_cfo, CFO_EMA_ALPHA); } else { INFO("No space for CFO computation. Frame starts at \n",peak_pos); } if (q->detect_cp) { if (peak_pos + find_offset >= 2*(q->fft_size + CP_EXT(q->fft_size))) { q->cp = sync_detect_cp(q, input, peak_pos + find_offset); } else { INFO("Not enough room to detect CP length. Peak position: %d\n", peak_pos); } } // Try to detect SSS if (q->sss_en) { /* Correct CFO with the averaged CFO estimation */ if (q->mean_cfo && q->correct_cfo) { cfo_correct(&q->cfocorr, input, input, -q->mean_cfo / q->fft_size); } // Set an invalid N_id_1 indicating SSS is yet to be detected q->N_id_1 = 1000; if (sync_sss(q, input, find_offset + peak_pos, q->cp) < 0) { INFO("No space for SSS processing. Frame starts at %d\n", peak_pos); } } // Return 1 (peak detected) even if we couldn't estimate CFO and SSS ret = 1; } else { ret = 0; } INFO("SYNC ret=%d N_id_2=%d find_offset=%d pos=%d peak=%.2f threshold=%.2f sf_idx=%d, CFO=%.3f KHz\n", ret, q->N_id_2, find_offset, peak_pos, q->peak_value, q->threshold, q->sf_idx, 15*q->mean_cfo); } else if (lte_N_id_2_isvalid(q->N_id_2)) { fprintf(stderr, "Must call sync_set_N_id_2() first!\n"); } return ret; }
int main(int argc, char **argv) { cf_t *input_buffer, *sf_symbols = NULL; int frame_cnt; ue_sync_t s; int pos; pss_synch_t pss; float peak; struct timeval t[3]; float mean_ce_time=0; bool signal_detected; lte_fft_t fft; lte_cell_t cell; bzero(&cell, sizeof(lte_cell_t)); parse_args(argc, argv); #ifndef DISABLE_GRAPHICS if (!disable_plots) { init_plots(); } #endif input_init(); if (ue_sync_init(&s, cuhd_set_rx_srate, cuhd_recv_wrapper, uhd)) { fprintf(stderr, "Error initiating UE sync module\n"); exit(-1); } ue_sync_pbch_enable(&s, true); signal_detected = true; frame_cnt = 0; mean_ce_time=0; uint32_t valid_frames=0; //uint32_t unaligned = 0; while (frame_cnt < nof_frames || nof_frames == -1) { int n = ue_sync_get_buffer(&s, &input_buffer); if (n < 0) { fprintf(stderr, "Error calling sync work()\n"); exit(-1); } if (n == 1 && ue_sync_get_sfidx(&s) == 0) { if (signal_detected) { cell = ue_sync_get_cell(&s); pss_synch_init_fft(&pss, SF_LEN(lte_symbol_sz(cell.nof_prb), cell.cp), lte_symbol_sz(cell.nof_prb)); pss_synch_set_N_id_2(&pss, cell.id%3); sf_symbols = vec_malloc(SLOT_LEN_RE(cell.nof_prb, cell.cp) * sizeof(cf_t)); if (!sf_symbols) { perror("malloc"); exit(-1); } lte_fft_init(&fft, cell.cp, cell.nof_prb); signal_detected = false; } mean_ce_time = (float) (mean_ce_time + (float) t[0].tv_usec * valid_frames) / (valid_frames+1); valid_frames++; #ifndef DISABLE_GRAPHICS if (!disable_plots && !(valid_frames % 5) && sf_symbols) { /* Run FFT for the second slot */ lte_fft_run_slot(&fft, input_buffer, sf_symbols); int i; int nof_re = SLOT_LEN_RE(cell.nof_prb, cell.cp); for (i = 0; i < nof_re; i++) { tmp_plot[i] = 10 * log10f(cabsf(sf_symbols[i])); if (isinf(tmp_plot[i])) { tmp_plot[i] = -80; } } plot_real_setNewData(&poutfft, tmp_plot, nof_re); } #endif pos = pss_synch_find_pss(&pss, input_buffer, &peak, NULL); /*if (pos > 962 || pos < 958) { unaligned++; } */ printf("CELL_ID: %3d CFO: %+.4f KHz, SFO: %+.4f Khz, TimeOffset: %4d, Exec: %3.2f\r", cell.id, ue_sync_get_cfo(&s)/1000, ue_sync_get_sfo(&s)/1000, pos, s.mean_exec_time); fflush(stdout); if (VERBOSE_ISINFO()) { printf("\n"); } } frame_cnt++; } printf("\nBye\n"); exit(0); }
int sync_run(sync_t *q, cf_t *input) { int N_id_2, peak_pos[3], sss_idx_n, sss_idx_e; int m0, m1; float m0_value_e, m1_value_e,m0_value_n, m1_value_n; int slot_id_e, N_id_1_e, slot_id_n, N_id_1_n; float peak_value[3]; float mean_value[3]; float max=-999; int i; int peak_detected; if (q->force_N_id_2 == -1) { for (N_id_2=0;N_id_2<3;N_id_2++) { peak_pos[N_id_2] = pss_synch_find_pss(&q->pss[N_id_2], input, &peak_value[N_id_2], &mean_value[N_id_2]); } for (i=0;i<3;i++) { if (peak_value[i] > max) { max = peak_value[i]; N_id_2 = i; } } } else { N_id_2 = q->force_N_id_2; peak_pos[N_id_2] = pss_synch_find_pss(&q->pss[N_id_2], input, &peak_value[N_id_2], &mean_value[N_id_2]); } q->peak_to_avg = peak_value[N_id_2] / mean_value[N_id_2]; DEBUG("PSS possible peak N_id_2=%d, pos=%d peak=%.2f par=%.2f threshold=%.2f\n", N_id_2, peak_pos[N_id_2], peak_value[N_id_2], q->peak_to_avg, q->threshold); /* If peak detected */ peak_detected = 0; if (peak_pos[N_id_2] - 128 >= 0) { if (q->pss_mode == ABSOLUTE) { if (peak_value[N_id_2] > q->threshold) { peak_detected = 1; } } else { if (q->peak_to_avg > q->threshold) { peak_detected = 1; } } } if (peak_detected) { q->cfo = pss_synch_cfo_compute(&q->pss[N_id_2], &input[peak_pos[N_id_2]-128]); INFO("PSS peak detected N_id_2=%d, pos=%d peak=%.2f par=%.2f th=%.2f cfo=%.4f\n", N_id_2, peak_pos[N_id_2], peak_value[N_id_2], q->peak_to_avg, q->threshold, q->cfo); if (q->sss_en) { /* Make sure we have enough room to find SSS sequence */ sss_idx_n = peak_pos[N_id_2]-2*(128+CP(128,CPNORM_LEN)); sss_idx_e = peak_pos[N_id_2]-2*(128+CP(128,CPEXT_LEN)); if (q->detect_cp) { if (sss_idx_n < 0 || sss_idx_e < 0) { INFO("Not enough room to decode SSS (%d, %d)\n", sss_idx_n, sss_idx_e); return -1; } } else { if (CP_ISNORM(q->cp)) { if (sss_idx_n < 0) { INFO("Not enough room to decode SSS (%d)\n", sss_idx_n); return -1; } } else { if (sss_idx_e < 0) { INFO("Not enough room to decode SSS (%d)\n", sss_idx_e); return -1; } } } N_id_1_e = -1; N_id_1_n = -1; slot_id_e = -1; slot_id_n = -1; /* try Normal CP length */ if (q->detect_cp || CP_ISNORM(q->cp)) { sss_synch_m0m1(&q->sss[N_id_2], &input[sss_idx_n], &m0, &m0_value_n, &m1, &m1_value_n); slot_id_n = 2 * sss_synch_subframe(m0, m1); N_id_1_n = sss_synch_N_id_1(&q->sss[N_id_2], m0, m1); } if (q->detect_cp || CP_ISEXT(q->cp)) { /* Now try Extended CP length */ sss_synch_m0m1(&q->sss[N_id_2], &input[sss_idx_e], &m0, &m0_value_e, &m1, &m1_value_e); slot_id_e = 2 * sss_synch_subframe(m0, m1); N_id_1_e = sss_synch_N_id_1(&q->sss[N_id_2], m0, m1); } /* Correlation with extended CP hypoteshis is greater than with normal? */ if ((q->detect_cp && m0_value_e * m1_value_e > m0_value_n * m1_value_n) || CP_ISEXT(q->cp)) { q->cp = CPEXT; q->slot_id = slot_id_e; q->N_id_1 = N_id_1_e; /* then is normal CP */ } else { q->cp = CPNORM; q->slot_id = slot_id_n; q->N_id_1 = N_id_1_n; } q->N_id_2 = N_id_2; INFO("SSS detected N_id_1=%d, slot_idx=%d, %s CP\n", q->N_id_1, q->slot_id, CP_ISNORM(q->cp)?"Normal":"Extended"); } return peak_pos[N_id_2]; } else { return -1; } }