/* CP detection algorithm taken from:
* "SSS Detection Method for Initial Cell Search in 3GPP LTE FDD/TDD Dual Mode Receiver"
* by Jung-In Kim et al.
*/
srslte_cp_t srslte_sync_detect_cp(srslte_sync_t *q, const cf_t *input, uint32_t peak_pos)
{
float R_norm=0, R_ext=0, C_norm=0, C_ext=0;
float M_norm=0, M_ext=0;
uint32_t cp_norm_len = SRSLTE_CP_LEN_NORM(7, q->fft_size);
uint32_t cp_ext_len = SRSLTE_CP_LEN_EXT(q->fft_size);
uint32_t nof_symbols = peak_pos/(q->fft_size+cp_ext_len);
if (nof_symbols > 3) {
nof_symbols = 3;
}
if (nof_symbols > 0) {
const cf_t *input_cp_norm = &input[peak_pos-nof_symbols*(q->fft_size+cp_norm_len)];
const cf_t *input_cp_ext = &input[peak_pos-nof_symbols*(q->fft_size+cp_ext_len)];
for (int i=0;i<nof_symbols;i++) {
R_norm += crealf(srslte_vec_dot_prod_conj_ccc(&input_cp_norm[q->fft_size], input_cp_norm, cp_norm_len));
C_norm += cp_norm_len * srslte_vec_avg_power_cf(input_cp_norm, cp_norm_len);
input_cp_norm += q->fft_size+cp_norm_len;
}
if (C_norm > 0) {
M_norm = R_norm/C_norm;
}
q->M_norm_avg = SRSLTE_VEC_EMA(M_norm/nof_symbols, q->M_norm_avg, CP_EMA_ALPHA);
for (int i=0;i<nof_symbols;i++) {
R_ext += crealf(srslte_vec_dot_prod_conj_ccc(&input_cp_ext[q->fft_size], input_cp_ext, cp_ext_len));
C_ext += cp_ext_len * srslte_vec_avg_power_cf(input_cp_ext, cp_ext_len);
input_cp_ext += q->fft_size+cp_ext_len;
}
if (C_ext > 0) {
M_ext = R_ext/C_ext;
}
q->M_ext_avg = SRSLTE_VEC_EMA(M_ext/nof_symbols, q->M_ext_avg, CP_EMA_ALPHA);
if (q->M_norm_avg > q->M_ext_avg) {
return SRSLTE_CP_NORM;
} else if (q->M_norm_avg < q->M_ext_avg) {
return SRSLTE_CP_EXT;
} else {
if (R_norm > R_ext) {
return SRSLTE_CP_NORM;
} else {
return SRSLTE_CP_EXT;
}
}
} else {
return SRSLTE_CP_NORM;
}
}
int main(int argc, char **argv) {
int ret;
cf_t *sf_buffer;
prog_args_t prog_args;
srslte_cell_t cell;
int64_t sf_cnt;
srslte_ue_sync_t ue_sync;
srslte_ue_mib_t ue_mib;
void *uhd;
srslte_ue_dl_t ue_dl;
srslte_ofdm_t fft;
srslte_chest_dl_t chest;
uint32_t nframes=0;
uint32_t nof_trials = 0;
uint32_t sfn = 0; // system frame number
int n;
uint8_t bch_payload[SRSLTE_BCH_PAYLOAD_LEN];
uint32_t sfn_offset;
float rssi_utra=0,rssi=0, rsrp=0, rsrq=0, snr=0;
cf_t *ce[SRSLTE_MAX_PORTS];
if (parse_args(&prog_args, argc, argv)) {
exit(-1);
}
if (prog_args.uhd_gain > 0) {
printf("Opening UHD device...\n");
if (cuhd_open(prog_args.uhd_args, &uhd)) {
fprintf(stderr, "Error opening uhd\n");
exit(-1);
}
cuhd_set_rx_gain(uhd, prog_args.uhd_gain);
} else {
printf("Opening UHD device with threaded RX Gain control ...\n");
if (cuhd_open_th(prog_args.uhd_args, &uhd, false)) {
fprintf(stderr, "Error opening uhd\n");
exit(-1);
}
cuhd_set_rx_gain(uhd, 50);
}
sigset_t sigset;
sigemptyset(&sigset);
sigaddset(&sigset, SIGINT);
sigprocmask(SIG_UNBLOCK, &sigset, NULL);
signal(SIGINT, sig_int_handler);
cuhd_set_master_clock_rate(uhd, 30.72e6);
/* set receiver frequency */
cuhd_set_rx_freq(uhd, (double) prog_args.uhd_freq);
cuhd_rx_wait_lo_locked(uhd);
printf("Tunning receiver to %.3f MHz\n", (double ) prog_args.uhd_freq/1000000);
uint32_t ntrial=0;
do {
ret = cuhd_search_and_decode_mib(uhd, &cell_detect_config, prog_args.force_N_id_2, &cell);
if (ret < 0) {
fprintf(stderr, "Error searching for cell\n");
exit(-1);
} else if (ret == 0 && !go_exit) {
printf("Cell not found after %d trials. Trying again (Press Ctrl+C to exit)\n", ntrial++);
}
} while (ret == 0 && !go_exit);
if (go_exit) {
exit(0);
}
/* set sampling frequency */
int srate = srslte_sampling_freq_hz(cell.nof_prb);
if (srate != -1) {
if (srate < 10e6) {
cuhd_set_master_clock_rate(uhd, 4*srate);
} else {
cuhd_set_master_clock_rate(uhd, srate);
}
printf("Setting sampling rate %.2f MHz\n", (float) srate/1000000);
float srate_uhd = cuhd_set_rx_srate(uhd, (double) srate);
if (srate_uhd != srate) {
fprintf(stderr, "Could not set sampling rate\n");
exit(-1);
}
} else {
fprintf(stderr, "Invalid number of PRB %d\n", cell.nof_prb);
exit(-1);
}
INFO("Stopping UHD and flushing buffer...\n",0);
cuhd_stop_rx_stream(uhd);
cuhd_flush_buffer(uhd);
if (srslte_ue_sync_init(&ue_sync, cell, cuhd_recv_wrapper, uhd)) {
fprintf(stderr, "Error initiating ue_sync\n");
return -1;
}
if (srslte_ue_dl_init(&ue_dl, cell)) {
fprintf(stderr, "Error initiating UE downlink processing module\n");
return -1;
}
if (srslte_ue_mib_init(&ue_mib, cell)) {
fprintf(stderr, "Error initaiting UE MIB decoder\n");
return -1;
}
/* Configure downlink receiver for the SI-RNTI since will be the only one we'll use */
srslte_ue_dl_set_rnti(&ue_dl, SRSLTE_SIRNTI);
/* Initialize subframe counter */
sf_cnt = 0;
if (srslte_ofdm_rx_init(&fft, cell.cp, cell.nof_prb)) {
fprintf(stderr, "Error initiating FFT\n");
return -1;
}
if (srslte_chest_dl_init(&chest, cell)) {
fprintf(stderr, "Error initiating channel estimator\n");
return -1;
}
int sf_re = SRSLTE_SF_LEN_RE(cell.nof_prb, cell.cp);
cf_t *sf_symbols = srslte_vec_malloc(sf_re * sizeof(cf_t));
for (int i=0;i<SRSLTE_MAX_PORTS;i++) {
ce[i] = srslte_vec_malloc(sizeof(cf_t) * sf_re);
}
cuhd_start_rx_stream(uhd);
float rx_gain_offset = 0;
/* Main loop */
while ((sf_cnt < prog_args.nof_subframes || prog_args.nof_subframes == -1) && !go_exit) {
ret = srslte_ue_sync_get_buffer(&ue_sync, &sf_buffer);
if (ret < 0) {
fprintf(stderr, "Error calling srslte_ue_sync_work()\n");
}
/* srslte_ue_sync_get_buffer returns 1 if successfully read 1 aligned subframe */
if (ret == 1) {
switch (state) {
case DECODE_MIB:
if (srslte_ue_sync_get_sfidx(&ue_sync) == 0) {
srslte_pbch_decode_reset(&ue_mib.pbch);
n = srslte_ue_mib_decode(&ue_mib, sf_buffer, bch_payload, NULL, &sfn_offset);
if (n < 0) {
fprintf(stderr, "Error decoding UE MIB\n");
return -1;
} else if (n == SRSLTE_UE_MIB_FOUND) {
srslte_pbch_mib_unpack(bch_payload, &cell, &sfn);
printf("Decoded MIB. SFN: %d, offset: %d\n", sfn, sfn_offset);
sfn = (sfn + sfn_offset)%1024;
state = DECODE_SIB;
}
}
break;
case DECODE_SIB:
/* We are looking for SI Blocks, search only in appropiate places */
if ((srslte_ue_sync_get_sfidx(&ue_sync) == 5 && (sfn%2)==0)) {
n = srslte_ue_dl_decode_rnti_rv(&ue_dl, sf_buffer, data, srslte_ue_sync_get_sfidx(&ue_sync), SRSLTE_SIRNTI,
((int) ceilf((float)3*(((sfn)/2)%4)/2))%4);
if (n < 0) {
fprintf(stderr, "Error decoding UE DL\n");fflush(stdout);
return -1;
} else if (n == 0) {
printf("CFO: %+6.4f KHz, SFO: %+6.4f Khz, NOI: %.2f, PDCCH-Det: %.3f\r",
srslte_ue_sync_get_cfo(&ue_sync)/1000, srslte_ue_sync_get_sfo(&ue_sync)/1000,
srslte_sch_average_noi(&ue_dl.pdsch.dl_sch),
(float) ue_dl.nof_detected/nof_trials);
nof_trials++;
} else {
printf("Decoded SIB1. Payload: ");
srslte_vec_fprint_byte(stdout, data, n/8);;
state = MEASURE;
}
}
break;
case MEASURE:
if (srslte_ue_sync_get_sfidx(&ue_sync) == 5) {
/* Run FFT for all subframe data */
srslte_ofdm_rx_sf(&fft, sf_buffer, sf_symbols);
srslte_chest_dl_estimate(&chest, sf_symbols, ce, srslte_ue_sync_get_sfidx(&ue_sync));
rssi = SRSLTE_VEC_EMA(srslte_vec_avg_power_cf(sf_buffer,SRSLTE_SF_LEN(srslte_symbol_sz(cell.nof_prb))),rssi,0.05);
rssi_utra = SRSLTE_VEC_EMA(srslte_chest_dl_get_rssi(&chest),rssi_utra,0.05);
rsrq = SRSLTE_VEC_EMA(srslte_chest_dl_get_rsrq(&chest),rsrq,0.05);
rsrp = SRSLTE_VEC_EMA(srslte_chest_dl_get_rsrp(&chest),rsrp,0.05);
snr = SRSLTE_VEC_EMA(srslte_chest_dl_get_snr(&chest),snr,0.05);
nframes++;
}
if ((nframes%100) == 0 || rx_gain_offset == 0) {
if (cuhd_has_rssi(uhd)) {
rx_gain_offset = 10*log10(rssi)-cuhd_get_rssi(uhd);
} else {
rx_gain_offset = cuhd_get_rx_gain(uhd);
}
}
// Plot and Printf
if ((nframes%10) == 0) {
printf("CFO: %+8.4f KHz, SFO: %+8.4f Khz, RSSI: %5.1f dBm, RSSI/ref-symbol: %+5.1f dBm, "
"RSRP: %+5.1f dBm, RSRQ: %5.1f dB, SNR: %5.1f dB\r",
srslte_ue_sync_get_cfo(&ue_sync)/1000, srslte_ue_sync_get_sfo(&ue_sync)/1000,
10*log10(rssi*1000) - rx_gain_offset,
10*log10(rssi_utra*1000)- rx_gain_offset,
10*log10(rsrp*1000) - rx_gain_offset,
10*log10(rsrq), 10*log10(snr));
if (srslte_verbose != SRSLTE_VERBOSE_NONE) {
printf("\n");
}
}
break;
}
if (srslte_ue_sync_get_sfidx(&ue_sync) == 9) {
sfn++;
if (sfn == 1024) {
sfn = 0;
}
}
} else if (ret == 0) {
printf("Finding PSS... Peak: %8.1f, FrameCnt: %d, State: %d\r",
srslte_sync_get_peak_value(&ue_sync.sfind),
ue_sync.frame_total_cnt, ue_sync.state);
}
sf_cnt++;
} // Main loop
srslte_ue_sync_free(&ue_sync);
cuhd_close(uhd);
printf("\nBye\n");
exit(0);
}
/** Finds the PSS sequence previously defined by a call to srslte_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 srslte_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 srslte_sync_find(srslte_sync_t *q, cf_t *input, uint32_t find_offset, uint32_t *peak_position)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL &&
srslte_N_id_2_isvalid(q->N_id_2) &&
fft_size_isvalid(q->fft_size))
{
int peak_pos;
ret = SRSLTE_SUCCESS;
if (peak_position) {
*peak_position = 0;
}
/* Estimate CFO using CP */
if (q->enable_cfo_corr) {
uint32_t cp_offset = srslte_cp_synch(&q->cp_synch, input, q->nof_symbols, q->nof_symbols, SRSLTE_CP_LEN_NORM(1,q->fft_size));
cf_t cp_corr_max = srslte_cp_synch_corr_output(&q->cp_synch, cp_offset);
float cfo = -carg(cp_corr_max) / M_PI / 2;
/* compute cumulative moving average CFO */
INFO("cp_offset_pos=%d, abs=%f, cfo=%f, mean_cfo=%f, nof_symb=%d\n",
cp_offset, cabs(cp_corr_max), cfo, q->mean_cfo, q->nof_symbols);
if (q->mean_cfo) {
q->mean_cfo = SRSLTE_VEC_EMA(cfo, q->mean_cfo, q->cfo_ema_alpha);
} else {
q->mean_cfo = cfo;
}
/* Correct CFO with the averaged CFO estimation */
srslte_cfo_correct(&q->cfocorr, input, input, -q->mean_cfo / q->fft_size);
}
if (q->find_cfo_i && q->enable_cfo_corr) {
float peak_value;
float max_peak_value = -99;
peak_pos = 0;
srslte_pss_synch_t *pss_obj[3] = {&q->pss_i[0], &q->pss, &q->pss_i[1]};
for (int cfo_i=0;cfo_i<3;cfo_i++) {
srslte_pss_synch_set_N_id_2(pss_obj[cfo_i], q->N_id_2);
int p = srslte_pss_synch_find_pss(pss_obj[cfo_i], &input[find_offset], &peak_value);
if (peak_value > max_peak_value) {
max_peak_value = peak_value;
peak_pos = p;
q->peak_value = peak_value;
q->cfo_i = cfo_i-1;
}
}
if (q->cfo_i != 0) {
srslte_vec_prod_ccc(input, q->cfo_i_corr[q->cfo_i<0?0:1], input, q->frame_size);
INFO("Compensating cfo_i=%d\n", q->cfo_i);
}
} else {
srslte_pss_synch_set_N_id_2(&q->pss, q->N_id_2);
peak_pos = srslte_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 SRSLTE_ERROR;
}
}
q->mean_peak_value = SRSLTE_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) {
// Try to detect SSS
if (q->sss_en) {
// 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) {
DEBUG("No space for SSS processing. Frame starts at %d\n", peak_pos);
}
}
if (q->detect_cp) {
if (peak_pos + find_offset >= 2*(q->fft_size + SRSLTE_CP_LEN_EXT(q->fft_size))) {
srslte_sync_set_cp(q, srslte_sync_detect_cp(q, input, peak_pos + find_offset));
} else {
DEBUG("Not enough room to detect CP length. Peak position: %d\n", peak_pos);
}
}
// Return 1 (peak detected) even if we couldn't estimate CFO and SSS
ret = 1;
} else {
ret = 0;
}
DEBUG("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->cfo_i+q->mean_cfo));
} else if (srslte_N_id_2_isvalid(q->N_id_2)) {
fprintf(stderr, "Must call srslte_sync_set_N_id_2() first!\n");
}
return ret;
}
/** Finds the PSS sequence previously defined by a call to srslte_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 srslte_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 srslte_sync_find(srslte_sync_t *q, cf_t *input, uint32_t find_offset, uint32_t *peak_position)
{
int ret = SRSLTE_ERROR_INVALID_INPUTS;
if (q != NULL &&
input != NULL &&
srslte_N_id_2_isvalid(q->N_id_2) &&
fft_size_isvalid(q->fft_size))
{
int peak_pos;
ret = SRSLTE_SUCCESS;
if (peak_position) {
*peak_position = 0;
}
srslte_pss_synch_set_N_id_2(&q->pss, q->N_id_2);
peak_pos = srslte_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 SRSLTE_ERROR;
}
q->mean_peak_value = SRSLTE_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 = srslte_pss_synch_cfo_compute(&q->pss, &input[find_offset+peak_pos-q->fft_size]);
/* compute cumulative moving average CFO */
q->mean_cfo = SRSLTE_VEC_EMA(cfo, q->mean_cfo, CFO_EMA_ALPHA);
} else {
DEBUG("No space for CFO computation. Frame starts at \n",peak_pos);
}
/* Correct CFO with the averaged CFO estimation */
if (q->correct_cfo) {
srslte_cfo_correct(&q->cfocorr, input, input, -q->mean_cfo / q->fft_size);
}
// Try to detect SSS
if (q->sss_en) {
// 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) {
DEBUG("No space for SSS processing. Frame starts at %d\n", peak_pos);
}
}
if (q->detect_cp) {
if (peak_pos + find_offset >= 2*(q->fft_size + SRSLTE_CP_LEN_EXT(q->fft_size))) {
q->cp = srslte_sync_detect_cp(q, input, peak_pos + find_offset);
} else {
DEBUG("Not enough room to detect CP length. Peak position: %d\n", peak_pos);
}
}
// Return 1 (peak detected) even if we couldn't estimate CFO and SSS
ret = 1;
} else {
ret = 0;
}
DEBUG("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 (srslte_N_id_2_isvalid(q->N_id_2)) {
fprintf(stderr, "Must call srslte_sync_set_N_id_2() first!\n");
}
return ret;
}
static int track_peak_ok(srslte_ue_sync_t *q, uint32_t track_idx) {
/* Make sure subframe idx is what we expect */
if ((q->sf_idx != srslte_sync_get_sf_idx(&q->strack)) &&
q->decode_sss_on_track &&
srslte_sync_sss_detected(&q->strack))
{
INFO("Warning: Expected SF idx %d but got %d! (%d frames)\n",
q->sf_idx, srslte_sync_get_sf_idx(&q->strack), q->frame_no_cnt);
q->frame_no_cnt++;
if (q->frame_no_cnt >= TRACK_MAX_LOST) {
INFO("\n%d frames lost. Going back to FIND\n", (int) q->frame_no_cnt);
q->state = SF_FIND;
}
} else {
q->frame_no_cnt = 0;
}
// Get sampling time offset
q->last_sample_offset = ((int) track_idx - (int) q->strack.max_offset/2 - (int) q->strack.fft_size);
// Adjust sampling time every q->sample_offset_correct_period subframes
uint32_t frame_idx = 0;
if (q->sample_offset_correct_period) {
frame_idx = q->frame_ok_cnt%q->sample_offset_correct_period;
q->mean_sample_offset += (float) q->last_sample_offset/q->sample_offset_correct_period;
} else {
q->mean_sample_offset = q->last_sample_offset;
}
// Compute cumulative moving average time offset */
if (!frame_idx) {
// Adjust RF sampling time based on the mean sampling offset
q->next_rf_sample_offset = (int) round(q->mean_sample_offset);
// Reset PSS averaging if correcting every a period longer than 1
if (q->sample_offset_correct_period > 1) {
srslte_sync_reset(&q->strack);
}
// Compute SFO based on mean sample offset
if (q->sample_offset_correct_period) {
q->mean_sample_offset /= q->sample_offset_correct_period;
}
q->mean_sfo = SRSLTE_VEC_EMA(q->mean_sample_offset, q->mean_sfo, q->sfo_ema);
if (q->next_rf_sample_offset) {
INFO("Time offset adjustment: %d samples (%.2f), mean SFO: %.2f Hz, %.5f samples/5-sf, ema=%f, length=%d\n",
q->next_rf_sample_offset, q->mean_sample_offset,
srslte_ue_sync_get_sfo(q),
q->mean_sfo, q->sfo_ema, q->sample_offset_correct_period);
}
q->mean_sample_offset = 0;
}
/* If the PSS peak is beyond the frame (we sample too slowly),
discard the offseted samples to align next frame */
if (q->next_rf_sample_offset > 0 && q->next_rf_sample_offset < MAX_TIME_OFFSET) {
DEBUG("Positive time offset %d samples.\n", q->next_rf_sample_offset);
if (q->recv_callback(q->stream, dummy, (uint32_t) q->next_rf_sample_offset, &q->last_timestamp) < 0) {
fprintf(stderr, "Error receiving from USRP\n");
return SRSLTE_ERROR;
}
q->next_rf_sample_offset = 0;
}
q->peak_idx = q->sf_len/2 + q->last_sample_offset;
q->frame_ok_cnt++;
return 1;
}
/* Decode a transport block according to 36.212 5.3.2
*
*/
static int decode_tb(srslte_sch_t *q,
srslte_softbuffer_rx_t *softbuffer, srslte_cbsegm_t *cb_segm,
uint32_t Qm, uint32_t rv, uint32_t nof_e_bits,
float *e_bits, uint8_t *data)
{
uint8_t parity[24];
uint8_t *p_parity = parity;
uint32_t par_rx, par_tx;
uint32_t i;
uint32_t cb_len, rp, wp, rlen, F, n_e;
if (q != NULL &&
data != NULL &&
softbuffer != NULL &&
e_bits != NULL &&
cb_segm != NULL)
{
if (cb_segm->tbs == 0 || cb_segm->C == 0) {
return SRSLTE_SUCCESS;
}
rp = 0;
rp = 0;
wp = 0;
uint32_t Gp = nof_e_bits / Qm;
uint32_t gamma=Gp;
if (cb_segm->C>0) {
gamma = Gp%cb_segm->C;
}
bool early_stop = true;
for (i = 0; i < cb_segm->C && early_stop; i++) {
/* Get read/write lengths */
if (i < cb_segm->C2) {
cb_len = cb_segm->K2;
} else {
cb_len = cb_segm->K1;
}
if (cb_segm->C == 1) {
rlen = cb_len;
} else {
rlen = cb_len - 24;
}
if (i == 0) {
F = cb_segm->F;
} else {
F = 0;
}
if (i <= cb_segm->C - gamma - 1) {
n_e = Qm * (Gp/cb_segm->C);
} else {
n_e = Qm * ((uint32_t) ceilf((float) Gp/cb_segm->C));
}
INFO("CB#%d: cb_len: %d, rlen: %d, wp: %d, rp: %d, F: %d, E: %d\n", i,
cb_len, rlen - F, wp, rp, F, n_e);
/* Rate Unmatching */
if (srslte_rm_turbo_rx(softbuffer->buffer_f[i], softbuffer->buff_size,
&e_bits[rp], n_e,
(float*) q->cb_out, 3 * cb_len + 12, rv, F)) {
fprintf(stderr, "Error in rate matching\n");
return SRSLTE_ERROR;
}
if (SRSLTE_VERBOSE_ISDEBUG()) {
DEBUG("CB#%d RMOUT: ", i);
srslte_vec_fprint_f(stdout, q->cb_out, 3*cb_len+12);
}
/* Turbo Decoding with CRC-based early stopping */
q->nof_iterations = 0;
uint32_t len_crc;
uint8_t *cb_in_ptr;
srslte_crc_t *crc_ptr;
early_stop = false;
srslte_tdec_reset(&q->decoder, cb_len);
do {
srslte_tdec_iteration(&q->decoder, (float*) q->cb_out, cb_len);
q->nof_iterations++;
if (cb_segm->C > 1) {
len_crc = cb_len;
cb_in_ptr = q->cb_in;
crc_ptr = &q->crc_cb;
} else {
len_crc = cb_segm->tbs+24;
cb_in_ptr = &q->cb_in[F];
crc_ptr = &q->crc_tb;
}
srslte_tdec_decision(&q->decoder, q->cb_in, cb_len);
/* Check Codeblock CRC and stop early if incorrect */
if (!srslte_crc_checksum(crc_ptr, cb_in_ptr, len_crc)) {
early_stop = true;
}
} while (q->nof_iterations < SRSLTE_PDSCH_MAX_TDEC_ITERS && !early_stop);
q->average_nof_iterations = SRSLTE_VEC_EMA((float) q->nof_iterations, q->average_nof_iterations, 0.2);
if (SRSLTE_VERBOSE_ISDEBUG()) {
DEBUG("CB#%d IN: ", i);
srslte_vec_fprint_b(stdout, q->cb_in, cb_len);
}
// If CB CRC is not correct, early_stop will be false and wont continue with rest of CBs
/* Copy data to another buffer, removing the Codeblock CRC */
if (i < cb_segm->C - 1) {
memcpy(&data[wp], &q->cb_in[F], (rlen - F) * sizeof(uint8_t));
} else {
DEBUG("Last CB, appending parity: %d to %d from %d and 24 from %d\n",
rlen - F - 24, wp, F, rlen - 24);
/* Append Transport Block parity bits to the last CB */
memcpy(&data[wp], &q->cb_in[F], (rlen - F - 24) * sizeof(uint8_t));
memcpy(parity, &q->cb_in[rlen - 24], 24 * sizeof(uint8_t));
}
/* Set read/write pointers */
wp += (rlen - F);
rp += n_e;
}
if (!early_stop) {
INFO("CB %d failed. TB is erroneous.\n",i-1);
return SRSLTE_ERROR;
} else {
INFO("END CB#%d: wp: %d, rp: %d\n", i, wp, rp);
// Compute transport block CRC
par_rx = srslte_crc_checksum(&q->crc_tb, data, cb_segm->tbs);
// check parity bits
par_tx = srslte_bit_unpack(&p_parity, 24);
if (!par_rx) {
INFO("\n\tCAUTION!! Received all-zero transport block\n\n", 0);
}
if (par_rx == par_tx) {
INFO("TB decoded OK\n",i);
return SRSLTE_SUCCESS;
} else {
INFO("Error in TB parity\n",i);
return SRSLTE_ERROR;
}
}
} else {
return SRSLTE_ERROR_INVALID_INPUTS;
}
}
/** Finds the PSS sequence previously defined by a call to srslte_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 srslte_sync_set_threshold()
* or 0 otherwise. Returns a negative number on error (if N_id_2 has not been set)
*
* The input signal is not modified. Any CFO correction is done in internal buffers
*
* The maximum of the correlation peak is always stored in *peak_position
*/
srslte_sync_find_ret_t srslte_sync_find(srslte_sync_t *q, const cf_t *input, uint32_t find_offset, uint32_t *peak_position)
{
srslte_sync_find_ret_t ret = SRSLTE_SYNC_ERROR;
int peak_pos = 0;
if (!q) {
return SRSLTE_ERROR_INVALID_INPUTS;
}
if (input != NULL &&
srslte_N_id_2_isvalid(q->N_id_2) &&
fft_size_isvalid(q->fft_size))
{
if (peak_position) {
*peak_position = 0;
}
const cf_t *input_ptr = input;
/* First CFO estimation stage is integer.
* Finds max PSS correlation for shifted +1/0/-1 integer versions.
* This should only used once N_id_2 is set
*/
if (q->cfo_i_enable) {
if (cfo_i_estimate(q, input_ptr, find_offset, &peak_pos, &q->cfo_i_value) < 0) {
fprintf(stderr, "Error calling finding PSS sequence at : %d \n", peak_pos);
return SRSLTE_ERROR;
}
// Correct it using precomputed signal and store in buffer (don't modify input signal)
if (q->cfo_i_value != 0) {
srslte_vec_prod_ccc((cf_t*) input_ptr, q->cfo_i_corr[q->cfo_i_value<0?0:1], q->temp, q->frame_size);
INFO("Compensating cfo_i=%d\n", q->cfo_i_value);
input_ptr = q->temp;
}
}
/* Second stage is coarse fractional CFO estimation using CP.
* In case of multi-cell, this can lead to incorrect estimations if CFO from different cells is different
*/
if (q->cfo_cp_enable) {
float cfo_cp = cfo_cp_estimate(q, input_ptr);
if (!q->cfo_cp_is_set) {
q->cfo_cp_mean = cfo_cp;
q->cfo_cp_is_set = true;
} else {
/* compute exponential moving average CFO */
q->cfo_cp_mean = SRSLTE_VEC_EMA(cfo_cp, q->cfo_cp_mean, q->cfo_ema_alpha);
}
INFO("CP-CFO: estimated=%f, mean=%f\n", cfo_cp, q->cfo_cp_mean);
/* Correct CFO with the averaged CFO estimation */
srslte_cfo_correct(&q->cfo_corr_frame, input_ptr, q->temp, -q->cfo_cp_mean / q->fft_size);
input_ptr = q->temp;
}
/* Find maximum of PSS correlation. If Integer CFO is enabled, correlation is already done
*/
if (!q->cfo_i_enable) {
srslte_pss_set_N_id_2(&q->pss, q->N_id_2);
peak_pos = srslte_pss_find_pss(&q->pss, &input_ptr[find_offset], q->threshold>0?&q->peak_value:NULL);
if (peak_pos < 0) {
fprintf(stderr, "Error calling finding PSS sequence at : %d \n", peak_pos);
return SRSLTE_ERROR;
}
}
INFO("PSS: id=%d, peak_pos=%d, peak_value=%f\n", q->N_id_2, peak_pos, q->peak_value);
// Save peak position
if (peak_position) {
*peak_position = (uint32_t) peak_pos;
}
// In case of decimation, this compensates for the constant time shift caused by the low pass filter
if(q->decimate && peak_pos < 0) {
peak_pos = 0 ;//peak_pos + q->decimate*(2);// replace 2 with q->filter_size -2;
}
/* If peak is over threshold, compute CFO and SSS */
if (q->peak_value >= q->threshold || q->threshold == 0) {
if (q->cfo_pss_enable && peak_pos >= q->fft_size) {
// Filter central bands before PSS-based CFO estimation
const cf_t *pss_ptr = &input_ptr[find_offset + peak_pos - q->fft_size];
if (q->pss_filtering_enabled) {
srslte_pss_filter(&q->pss, pss_ptr, q->pss_filt);
pss_ptr = q->pss_filt;
}
// PSS-based CFO estimation
q->cfo_pss = srslte_pss_cfo_compute(&q->pss, pss_ptr);
if (!q->cfo_pss_is_set) {
q->cfo_pss_mean = q->cfo_pss;
q->cfo_pss_is_set = true;
} else if (15000*fabsf(q->cfo_pss) < MAX_CFO_PSS_OFFSET) {
q->cfo_pss_mean = SRSLTE_VEC_EMA(q->cfo_pss, q->cfo_pss_mean, q->cfo_ema_alpha);
}
INFO("PSS-CFO: filter=%s, estimated=%f, mean=%f\n",
q->pss_filtering_enabled?"yes":"no", q->cfo_pss, q->cfo_pss_mean);
}
// If there is enough space for CP and SSS estimation
if (peak_pos + find_offset >= 2 * (q->fft_size + SRSLTE_CP_LEN_EXT(q->fft_size))) {
// If SSS search is enabled, correlate SSS sequence
if (q->sss_en) {
// Set an invalid N_id_1 indicating SSS is yet to be detected
q->N_id_1 = 1000;
int sss_idx = find_offset + peak_pos - 2 * q->fft_size -
SRSLTE_CP_LEN(q->fft_size, (SRSLTE_CP_ISNORM(q->cp) ? SRSLTE_CP_NORM_LEN : SRSLTE_CP_EXT_LEN));
const cf_t *sss_ptr = &input_ptr[sss_idx];
// Correct CFO if detected in PSS
if (q->cfo_pss_enable) {
srslte_cfo_correct(&q->cfo_corr_symbol, sss_ptr, q->sss_filt, -q->cfo_pss_mean / q->fft_size);
// Equalize channel if estimated in PSS
if (q->sss_channel_equalize && q->pss.chest_on_filter && q->pss_filtering_enabled) {
srslte_vec_prod_ccc(&q->sss_filt[q->fft_size/2-SRSLTE_PSS_LEN/2], q->pss.tmp_ce,
&q->sss_filt[q->fft_size/2-SRSLTE_PSS_LEN/2], SRSLTE_PSS_LEN);
}
sss_ptr = q->sss_filt;
}
if (sync_sss_symbol(q, sss_ptr) < 0) {
fprintf(stderr, "Error correlating SSS\n");
return -1;
}
}
// Detect CP length
if (q->detect_cp) {
srslte_sync_set_cp(q, srslte_sync_detect_cp(q, input_ptr, peak_pos + find_offset));
} else {
DEBUG("Not enough room to detect CP length. Peak position: %d\n", peak_pos);
}
ret = SRSLTE_SYNC_FOUND;
} else {
ret = SRSLTE_SYNC_FOUND_NOSPACE;
}
} else {
ret = SRSLTE_SYNC_NOFOUND;
}
DEBUG("SYNC ret=%d N_id_2=%d find_offset=%d frame_len=%d, pos=%d peak=%.2f threshold=%.2f sf_idx=%d, CFO=%.3f kHz\n",
ret, q->N_id_2, find_offset, q->frame_size, peak_pos, q->peak_value,
q->threshold, q->sf_idx, 15*(srslte_sync_get_cfo(q)));
} else if (srslte_N_id_2_isvalid(q->N_id_2)) {
fprintf(stderr, "Must call srslte_sync_set_N_id_2() first!\n");
}
return ret;
}
