int srslte_ue_mib_decode(srslte_ue_mib_t * q,
uint8_t bch_payload[SRSLTE_BCH_PAYLOAD_LEN], uint32_t *nof_tx_ports, int *sfn_offset)
{
int ret = SRSLTE_SUCCESS;
cf_t *ce_slot1[SRSLTE_MAX_PORTS];
/* Run FFT for the slot symbols */
srslte_ofdm_rx_sf(&q->fft);
/* Get channel estimates of sf idx #0 for each port */
ret = srslte_chest_dl_estimate(&q->chest, q->sf_symbols, q->ce, 0);
if (ret < 0) {
return SRSLTE_ERROR;
}
/* Reset decoder if we missed a frame */
if (q->frame_cnt > 8) {
INFO("Resetting PBCH decoder after %d frames\n", q->frame_cnt);
srslte_ue_mib_reset(q);
}
for (int i=0;i<SRSLTE_MAX_PORTS;i++) {
ce_slot1[i] = &q->ce[i][SRSLTE_SLOT_LEN_RE(q->chest.cell.nof_prb, q->chest.cell.cp)];
}
/* Decode PBCH */
ret = srslte_pbch_decode(&q->pbch, &q->sf_symbols[SRSLTE_SLOT_LEN_RE(q->chest.cell.nof_prb, q->chest.cell.cp)],
ce_slot1, 0,
bch_payload, nof_tx_ports, sfn_offset);
if (ret < 0) {
fprintf(stderr, "Error decoding PBCH (%d)\n", ret);
} else if (ret == 1) {
INFO("MIB decoded: %u\n", q->frame_cnt);
srslte_ue_mib_reset(q);
ret = SRSLTE_UE_MIB_FOUND;
} else {
ret = SRSLTE_UE_MIB_NOTFOUND;
INFO("MIB not decoded: %u\n", q->frame_cnt);
q->frame_cnt++;
}
return ret;
}
int main(int argc, char **argv) {
srslte_pbch_t pbch;
uint8_t bch_payload_tx[SRSLTE_BCH_PAYLOAD_LEN], bch_payload_rx[SRSLTE_BCH_PAYLOAD_LEN];
int i, j;
cf_t *ce[SRSLTE_MAX_PORTS];
int nof_re;
cf_t *slot1_symbols[SRSLTE_MAX_PORTS];
uint32_t nof_rx_ports;
parse_args(argc,argv);
nof_re = SRSLTE_SLOT_LEN_RE(cell.nof_prb, SRSLTE_CP_NORM);
/* init memory */
for (i=0;i<cell.nof_ports;i++) {
ce[i] = malloc(sizeof(cf_t) * nof_re);
if (!ce[i]) {
perror("malloc");
exit(-1);
}
for (j=0;j<nof_re;j++) {
ce[i][j] = 1;
}
slot1_symbols[i] = malloc(sizeof(cf_t) * nof_re);
if (!slot1_symbols[i]) {
perror("malloc");
exit(-1);
}
}
if (srslte_pbch_init(&pbch, cell)) {
fprintf(stderr, "Error creating PBCH object\n");
exit(-1);
}
srand(time(NULL));
for (i=0;i<SRSLTE_BCH_PAYLOAD_LEN;i++) {
bch_payload_tx[i] = rand()%2;
}
srslte_pbch_encode(&pbch, bch_payload_tx, slot1_symbols, 0);
/* combine outputs */
for (i=1;i<cell.nof_ports;i++) {
for (j=0;j<nof_re;j++) {
slot1_symbols[0][j] += slot1_symbols[i][j];
}
}
srslte_pbch_decode_reset(&pbch);
if (1 != srslte_pbch_decode(&pbch, slot1_symbols[0], ce, 0, bch_payload_rx, &nof_rx_ports, NULL)) {
printf("Error decoding\n");
exit(-1);
}
srslte_pbch_free(&pbch);
for (i=0;i<cell.nof_ports;i++) {
free(ce[i]);
free(slot1_symbols[i]);
}
printf("Tx ports: %d - Rx ports: %d\n", cell.nof_ports, nof_rx_ports);
printf("Tx payload: ");
srslte_vec_fprint_hex(stdout, bch_payload_tx, SRSLTE_BCH_PAYLOAD_LEN);
printf("Rx payload: ");
srslte_vec_fprint_hex(stdout, bch_payload_rx, SRSLTE_BCH_PAYLOAD_LEN);
if (nof_rx_ports == cell.nof_ports && !memcmp(bch_payload_rx, bch_payload_tx, sizeof(uint8_t) * SRSLTE_BCH_PAYLOAD_LEN)) {
printf("OK\n");
exit(0);
} else {
printf("Error\n");
exit(-1);
}
}
int main(int argc, char **argv) {
uint8_t bch_payload[SRSLTE_BCH_PAYLOAD_LEN];
int n;
uint32_t nof_tx_ports, sfn_offset;
cf_t *ce_slot1[SRSLTE_MAX_PORTS];
if (argc < 3) {
usage(argv[0]);
exit(-1);
}
parse_args(argc,argv);
if (base_init()) {
fprintf(stderr, "Error initializing receiver\n");
exit(-1);
}
int frame_cnt = 0;
int nof_decoded_mibs = 0;
int nread = 0;
do {
nread = srslte_filesource_read(&fsrc, input_buffer, FLEN);
if (nread > 0) {
// process 1st subframe only
srslte_ofdm_rx_sf(&fft, input_buffer, fft_buffer);
/* Get channel estimates for each port */
srslte_chest_dl_estimate(&chest, fft_buffer, ce, 0);
INFO("Decoding PBCH\n", 0);
for (int i=0;i<SRSLTE_MAX_PORTS;i++) {
ce_slot1[i] = &ce[i][SRSLTE_SLOT_LEN_RE(cell.nof_prb, cell.cp)];
}
srslte_pbch_decode_reset(&pbch);
n = srslte_pbch_decode(&pbch, &fft_buffer[SRSLTE_SLOT_LEN_RE(cell.nof_prb, cell.cp)],
ce_slot1, srslte_chest_dl_get_noise_estimate(&chest),
bch_payload, &nof_tx_ports, &sfn_offset);
if (n == 1) {
nof_decoded_mibs++;
} else if (n < 0) {
fprintf(stderr, "Error decoding PBCH\n");
exit(-1);
}
frame_cnt++;
} else if (nread < 0) {
fprintf(stderr, "Error reading from file\n");
exit(-1);
}
} while(nread > 0 && frame_cnt < nof_frames);
base_free();
if (frame_cnt == 1) {
if (n == 0) {
printf("Could not decode PBCH\n");
exit(-1);
} else {
printf("MIB decoded OK. Nof ports: %d. SFN offset: %d Payload: ", nof_tx_ports, sfn_offset);
srslte_vec_fprint_hex(stdout, bch_payload, SRSLTE_BCH_PAYLOAD_LEN);
if (nof_tx_ports == 2 && sfn_offset == 0 && !memcmp(bch_payload, bch_payload_file, SRSLTE_BCH_PAYLOAD_LEN)) {
printf("This is the signal.1.92M.dat file\n");
exit(0);
} else {
printf("This is an unknown file\n");
exit(-1);
}
}
} else {
printf("Decoded %d/%d MIBs\n", nof_decoded_mibs, frame_cnt);
}
}